TW201709252A - Ion implantation system - Google Patents

Abstract

In one aspect, an ion implantation system is disclosed, which comprises a deceleration system configured to receive an ion beam and decelerate the ion beam at a deceleration ratio of at least 2, and an electrostatic bend disposed downstream of the deceleration system for causing a deflection of the ion beam. The electrostatic bend includes three tandem electrode pairs for receiving the decelerated beam, where each electrode pair has an inner and an outer electrode spaced apart to allow passage of the ion beam therethrough. Each of the electrodes of the end electrode pair is held at an electric potential less than an electric potential at which any of the electrodes of the middle electrode pair is held and the electrodes of the first electrode pair are held at a lower electric potential relative to the electrodes of the middle electrode pair.

Description

Ion beam line

The present teachings generally relate to ion implantation systems and methods that include systems and methods for adjusting the current density of a ribbon ion beam to increase its profile uniformity.

Ion implantation techniques have been used to implant ions into semiconductors to make integrated circuits for more than 30 years. Traditionally, such ion implantation uses three types of ion implanters: medium current, high current, and high energy implanters. The ion source included in the high current implanter typically includes an extraction aperture in the form of a slit having a high aspect ratio to improve the effect of space charge. A one-dimensional ion beam drawn from such an ion source can be focused into an elliptical profile to create a substantially circular ion beam profile on a wafer onto which the ion beam is incident.

Some recent commercial high current ion implanters have so-called ribbon ion beams impinging on a wafer to implant ions therein, which nominally exhibit a one-dimensional profile. The use of such ribbon ion beams provides several advantages for wafer processing. For example, the ribbon ion beam can have a long dimension beyond the diameter of the wafer so that it can remain stationary, scanning the wafer only in a dimension orthogonal to the direction of propagation of the ion beam over the entire wafer. Implant ions on it. Furthermore, the ribbon ion beam can tolerate higher currents on the wafer.

However, the use of ribbon ion beams in ion implantation can cause many challenges war. For example, the longitudinal profile of the ion beam requires high uniformity to achieve acceptable dose uniformity of the implanted ions. The achievement of acceptable longitudinal uniformity of the ribbon ion beam used to process the wafer can be more challenging as the wafer size increases (eg, the next generation of 450-mm wafers replaces the current primary 300-mm wafer).

In some conventional ion implantation systems, corrector optics are incorporated into the ion beam line to change the charge density of the ion beam during ion beam delivery. However, if the ion beam profile exhibits high non-uniformity immediately after exiting from the ion source, or due to aberrations caused by space charge loading or beam transport optics, this method is usually Unable to produce sufficient ion beam uniformity.

Thus, there is a need for an enhanced ion implantation system that addresses the above disadvantages. In particular, there is a need for an improved system and method for ion implantation that includes an enhanced system and method for generating an ion beam having a desired energy and a desired ion beam profile along an ion beam line.

In one aspect, a system for varying the energy of a ribbon ion beam is disclosed, including a calibration device configured to receive a ribbon beam and adjust current density along a longitudinal dimension of the ion beam a profile; at least one deceleration/acceleration component defining a deceleration/acceleration region for decelerating or accelerating the ion beam as the ion beam passes through the at least one deceleration/acceleration component; a focusing lens for reducing the ion The beam diverges along its lateral dimension; and an electrostatic bend disposed downstream of the deceleration/acceleration zone to promote deflection of the ion beam.

In some embodiments, the calibration device can include a plurality of spaced electrode pairs stacked along a longitudinal dimension of the ion beam, each pair of electrodes being separated to form a A gap for the passage of the ion beam, wherein the pair of electrodes are configured to be individually biasable by application of an electrostatic voltage to locally bias the ion beam along a longitudinal dimension. A variety of different electrode types can be used. In some embodiments, the pair of electrodes can include a plate electrode configured to be substantially parallel or perpendicular to a plane formed by the direction of propagation of the ion beam and its lateral dimension. The system can further include at least one voltage source for applying the electrostatic voltages to the electrode pairs of the calibration device.

A controller coupled to the at least one voltage source can control the application of the electrostatic voltages to the pair of electrodes. For example, the controller can be configured to instruct the voltage source to apply an electrostatic voltage to the pair of electrodes to locally bias at least a portion of the ion beam to increase a current density profile along a longitudinal dimension of the ion beam. Uniformity.

The controller may be configured to: for example, determine the current density profile of the ion beam after passing the ion beam through an analyzer magnet or a plane of the substrate on which the ion beam is incident The electrostatic voltages applied to the electrode pairs of the calibration device.

In some embodiments, the controller is configured to apply a time varying voltage to the electrode pair of the calibration device. For example, the controller can be configured to vary the voltage applied to the pair of electrodes of the correcting device in time to cause the ion beam to oscillate along the longitudinal dimension. The oscillating motion of the ion beam can exhibit, for example, an amplitude equal to or less than about 20 mm in the range of from about 10 mm to about 20 mm. For example, the frequency of the oscillations can range from about 1 Hz to about 1 kHz.

The focusing lens can include at least one focusing element, for example, a pair of opposing electrodes spaced apart to form a gap for receiving the ion beam. Furthermore, the deceleration/acceleration component can include a pair of spaced apart to form a lateral direction for receiving the ion beam The electrode of the gap. The focusing element and the decelerating/accelerating element may be disposed opposite each other to form a gap therebetween and may be maintained at a different potential such that ions pass through the gap, causing the plasma to slow or accelerate.

In some embodiments, at least one of the focusing electrodes can include a curved upstream side end face configured to reduce the ion beam diverging along its longitudinal dimension. For example, the upstream side end surface of the focusing electrode may be a concave surface having a radius of curvature of about 1 m to about 10 m.

In some embodiments, the at least one deceleration/acceleration component is disposed on a downstream side of the correction device and the at least one focusing component is disposed on a downstream side of the deceleration/acceleration component.

The focusing element can form a gap therebetween with respect to the electrostatic bend configuration, wherein the focusing element and the electrostatic bend are maintained at different potentials to form an application in the gap to reduce the ion beam along the The electric field of the lateral dimension diverging.

In some embodiments, the electrostatic bend includes an inner electrode and an opposite outer electrode that are held at different potentials to promote deflection of the ion beam. The static bend tube may further include an intermediate electrode disposed on a downstream side of the inner electrode and opposite to the outer electrode, wherein the inner electrode and the intermediate electrode are configured to be applied with independent potentials. In some cases, the outer electrode and the intermediate electrode can be maintained at the same potential.

In some embodiments, the external electrode of the electrostatic bend includes an upstream portion and a downstream portion that are disposed at an angle relative to each other such that the downstream portion can be captured in the ion beam. At least a portion of a sexual particle. The upstream and downstream portions may integrally constitute the outer electrode, or they may be electrically coupled Individual parts.

In some embodiments, the system can further include another calibration device disposed on a downstream side of the electrostatic bend, the other calibration device configured to adjust a current density profile of the ion beam along the longitudinal dimension . In some combinations, the downstream correction device can include a plurality of spaced apart electrode pairs stacked along a longitudinal dimension of the ion beam, each pair of electrodes being spaced apart to form a gap for the passage of the ion beam, wherein The electrode pairs are configured to be individually biasable by application of an electrostatic voltage to locally bias the ion beam along the longitudinal dimension.

In some embodiments, the pairs of electrodes of the correcting devices are offset from one another along the longitudinal dimension of the ion beam. For example, the pair of electrodes of the downstream correcting device (along the longitudinal dimension of the ion beam) can be vertically offset relative to the individual electrode pairs of the upstream correcting device by one-half of the longitudinal height of the electrodes of the correcting devices (pixel size) Half of it).

In some embodiments, the system can further include another focusing lens (also referred to herein as a second focusing lens) disposed on a downstream side of the other correcting device to reduce the ion beam along the lateral direction The size is divergent. Furthermore, in some cases, an electrical ground element may be disposed on the downstream side of the other focus lens. The electrical ground element includes, for example, a pair of electrical ground electrodes spaced apart to allow the ion beam to pass therethrough. The second focusing lens may include at least one focusing element configured to form a gap therebetween with respect to the grounding element, wherein a potential difference between the focusing element and the grounding element generates an electric field in the gap to reduce the ion beam edge The lateral dimension diverges.

In other aspects, a system for decelerating a ribbon beam is disclosed, comprising at least one deceleration element defining a region for receiving the ribbon beam And decelerating the ions; at least one pair of deflecting electrodes spaced apart to receive and deflect the decelerating ion beam therebetween; and a calibration device configured to provide a pass for the deflecting ion beam Channels and adjusting the current density profile of the ion beam in a non-dispersive plane.

In some embodiments, the calibration device can include a plurality of spaced electrode pairs stacked along a longitudinal dimension of the ion beam, each pair of electrodes being separated to form a gap for the ion beam to pass through, wherein the electrodes The pair is configured to be individually biasable by application of an electrostatic voltage to locally bias the ion beam along the longitudinal dimension. In some embodiments, the plurality of spaced electrode pairs may include inner and outer opposing electrodes and an intermediate electrode disposed on a downstream side of the inner electrode and opposite to the outer electrode, wherein the outer electrode, the inner electrode, and the intermediate electrode The system is configured to remain at an independent potential. For example, the inner electrode and the outer electrode can be maintained at different potentials to promote deflection of the ion beam while the outer electrode and the intermediate electrode are maintained at the same potential. The outer electrode can include an upstream portion and a downstream portion, wherein the downstream portion is disposed at an angle relative to the upstream portion to capture neutral particles present in the ion beam. In some embodiments, the upstream and downstream portions of the outer electrode integrally form the outer electrode.

The system can further include at least one voltage source for applying the electrostatic voltages to the electrode pairs of the calibration device. A controller coupled to the at least one voltage source can be provided to adjust the voltage of the pair of electrodes applied to the calibration device. For example, the controller can determine the voltage applied to the pair of electrodes of the calibration device based on, for example, the measured current density profile of the received ion beam.

The system can further include a focusing lens configured to reduce the ion beam diverging along its lateral dimension. The focusing lens may include at least one focus An element, such as a pair of electrodes, is spaced apart to allow the ion beam to pass therethrough. In some embodiments, an electrical ground element, such as a pair of spaced electrodes, is disposed on a downstream side of the focusing element. The electrical ground element can be disposed relative to the focusing element to form a gap therebetween. The ground element and the focusing element can be maintained at different potentials to form an electric field in the gap to reduce the electric field that the ion beam diverges along the lateral dimension.

In another aspect, an ion implantation system is disclosed that includes an ion source adapted to generate a ribbon ion beam, an analytical magnet for receiving the ribbon ion beam and generating a mass selection (mass a -selected band ion beam; and a calibration system configured to receive the mass selective ribbon ion beam and adjust a current density profile of the ion beam along its longitudinal dimension to produce a along the longitudinal dimension An output ribbon ion beam of substantially uniform current density profile.

In some embodiments, the calibration system can be further configured to decelerate or accelerate the ions of the received mass selective ion beam to produce a decelerating/accelerating output ribbon ion having a substantially uniform current density profile along the longitudinal dimension. bundle. In some embodiments, the output ribbon ion beam exhibits a current density profile having a root mean square (RMS) deviation or inhomogeneity of equal to or less than about 5% along the longitudinal dimension. For example, the output ribbon ion beam can exhibit an RMS deviation or non-uniformity along the longitudinal dimension that is equal to or less than about 4% or equal to or less than about 3% or equal to or less than about 2% or equal to or less than about 1%. Sex current density profile.

In some embodiments, the calibration system in the ion implantation system described above can further include a focusing lens for reducing the divergence of the ribbon ion beam along its lateral dimension. Furthermore, in some embodiments, the calibration system can be configured to remove neutral particles (eg, neutral atoms and/or molecules) present in the mass selective ion beam. At least part of it. For example, the calibration system includes an electrostatic bend to propagate the neutral particles in their propagation direction to be beam stop (eg, an electrode outside the electrostatic bend) Part of the capture captures the direction of propagation of ions in the ion beam.

The ion implantation system can further include an end-station for holding a substrate (e.g., a wafer), wherein the output ribbon ion beam propagates to the end station to be incident on the substrate. In some embodiments, the calibration system can be configured to adjust a direction of propagation of the ion beam such that the output ribbon beam is oriented at a desired angle (eg, a 90 degree angle) to the surface of the substrate. It is incident on the surface of the substrate.

In some embodiments, the calibration system of the ion implantation system can cause the oscillating motion of the ion beam to improve the dose uniformity of the ions implanted in the substrate by the output ribbon beam.

In some embodiments, the calibration system of the ion implantation system can include at least one calibration device for adjusting a current density profile of the ion beam along the longitudinal dimension. Such a calibration device can include, for example, a plurality of spaced electrode pairs stacked along a longitudinal dimension of the ion beam, each pair of electrodes being separated to form a gap for the passage of the ion beam, wherein the electrode pairs are configured to It is individually biasable by the application of an electrostatic voltage to locally deflect the ion beam in the non-dispersive plane. The ion implantation system can also include at least one voltage source for applying a voltage to the electrode pair of the calibration device, and a controller coupled to the at least one voltage source for adjusting the application of the pair of electrodes Voltage.

In some aspects, a method for altering the energy of a ribbon ion beam is disclosed, comprising passing a ribbon ion beam through an area in which an electric field is present, such that The ions of the ion beam are decelerated or accelerated, the current density profile of the ribbon beam along its longitudinal dimension is adjusted, and the ribbon ion beam is diverged along its lateral dimension. The step of reducing the divergence of the ion beam includes passing the ion beam through a focusing lens.

In some embodiments, the ribbon ion beam can have an initial energy between about 10 keV and about 100 keV. In some embodiments, the step of decelerating or accelerating ions of the ion beam changes the energy of the ion beam by a factor of from about 1 to about 30.

The step of adjusting the current density profile of the ion beam along its longitudinal dimension may comprise using a calibration device adapted to locally deflect the ion beam along the longitudinal dimension to produce a substantially uniform current along the longitudinal dimension. Density profile.

In some aspects, a method of implanting ions in a substrate is disclosed, the method comprising: extracting a ribbon ion beam from an ion source; passing the ribbon ion beam through an analytical magnet to generate a mass selective ribbon ion beam Adjusting the mass to select a current density profile of the ribbon beam along at least one of its longitudinal dimensions to produce an output ribbon ion beam having a substantially uniform current density profile along the longitudinal dimension; and directing the output ribbon ion The beam is applied to a substrate to implant ions into the substrate.

In some embodiments, a calibration device can be configured to perform the step of adjusting the current density profile of the mass selective ribbon ion beam. For example, a calibration device can adjust the current density profile of the mass selective ribbon beam to obtain an ion beam that exhibits a substantially uniform current density profile.

In some embodiments, the ion implantation method can further include decelerating or accelerating ions of the mass selective ribbon ion beam such that the output ribbon ion beam has an energy different from the energy of the mass selective ribbon ion beam. .

In some embodiments, the implanted ion dose can be between about 10 ¹² cm ^-2 and about 10 ¹⁶ cm ^-2 . The ionic current can be, for example, tens of microamps (e.g., 20 microamperes) to tens of milliamperes (e.g., 60 milliamperes), for example, between about 50 microamps to about 50 milliamps, or, for example, about 2 milliamps to about 50 mAh.

In many ion implantation applications, even when an acceleration/deceleration system operates to decelerate the received ions at a moderate reduction ratio, one consists of two separate electrodes and is placed downstream of the acceleration/deceleration system. An electrostatic bend (e.g., the above-described electrostatic bend) can effectively bend an ion beam without causing significant angular divergence ("blow-up") of the ion beam. However, it has been found that the use of a conventional electrostatic bend on one of the downstream sides of a deceleration system configured to decelerate ions at a high reduction ratio may cause over-focusing of the plasma, which is at the ion When the beam passes through the downstream component, it will in turn cause the ion beam to spread. The scattering of the ion beam causes ion loss and can interfere with the operation of the ion implantation system. In addition, in some conventional ion implantation systems, the use of a focusing lens that requires a high voltage may cause an instantaneous ion beam, for example, due to arcing and contaminants generated in a neutral atom/molecular form via a charge exchange reaction. Stability. Some aspects of the technology discussed below are related to the resolution of these problems.

In one aspect, an ion implantation system is disclosed that includes a deceleration system configured to receive an ion beam and decelerate the ion beam at a reduction ratio of at least 2; and an electrostatic bend configured in The downstream side of the deceleration system to cause the ion beam to deflect. The static bend tube includes a first electrode pair disposed on a downstream side of the deceleration system to receive the decelerating ion beam, the first electrode pair having a separate inner electrode and an outer electrode to allow the ion beam to be Passing through; a second electrode pair disposed on a downstream side of the first electrode pair and having a separate inner electrode and an outer portion An electrode to allow the ion beam to pass therethrough; and a last electrode pair disposed on a downstream side of the second electrode pair and having a separate inner electrode and an outer electrode to allow the ion beam to pass therethrough. The first, second and last electrode pairs are configured to be independently biasable. In some embodiments, each of the electrodes of the last electrode pair is maintained at a potential that is less than the potential held by either of the electrodes of the second electrode pair. The electrodes of the first electrode pair are also maintained at a lower potential relative to the electrodes of the second electrode pair.

In some embodiments, the deceleration system is configured to provide in the range of from about 5 to about 100 (eg, in the range of from about 10 to about 80, or in the range of from about 20 to about 60, or at about 30 to Reduction ratio of about 50).

In some embodiments, the internal electrodes of each of the pair of electrodes are maintained at a potential that is less than the potential held by the individual external electrodes of the pair of electrodes to promote a bias of the ion beam formed by the positively charged particles. .

The inner and outer electrodes of the first electrode pair may form an angle with respect to one of the second electrode pairs. Furthermore, each of the inner and outer electrodes of the last electrode pair may form an angle with respect to one of the second electrode pairs.

In some embodiments, such that the outside of the first electrode and the last electrode pair held at a first potential V ₁ and the inner electrodes of those first and last electrode held at a second potential V _2. Moreover, that the second electrode is electrically grounded and that the pair of electrodes of the second electrode outside the pair of electrodes held at a third potential V ₃ within. The voltage V ₁ can be greater than the voltage V ₂ . For example, V ₁ can range from about 0V to about -30kV, V ₂ can range from about 0V (zero volts) to about -30kV (negative 30kV), and V ₃ can range from about 0V to about + Within the range of 30kV.

In some embodiments, the ion beam is a ribbon ion beam, while in other embodiments, the ion beam is a circular ion beam.

In some embodiments, the ion beam received by the deceleration system has an ion energy in the range of from about 10 keV to about 60 keV (eg, in the range of from about 10 keV to about 20 keV) and in a range from about 0.1 mA to about 40 mA. Ion current (eg, in the range of about 5 mA to about 40 mA).

In some embodiments, the deceleration system includes a reduction element that is separate from a downstream focusing element to define a gap therebetween. The deceleration system can include two relatively separate equipotential electrode portions with a passage for the passage of the ion beam therebetween. The focusing element may also include two equipotential separating electrode portions with a passage for the passage of the ion beam therebetween. In some embodiments, the depolarizing element and the separate electrode portions of each of the focusing elements may be connected at their top and bottom ends to constitute, for example, a square electrode. The decelerating element and the electrodes of the focusing element are maintained at different potentials to provide an electric field in the gap to decelerate the received ion beam. The electric field also causes the ion beam to focus as it passes through the gap.

The ion implantation system may further include an ion source for generating the ion beam; and an analysis magnet disposed on a downstream side of the ion source and on an upstream side of the deceleration system for receiving the ion source The ion beam and a mass selective ion beam are generated.

In a related aspect, an ion implantation system is disclosed, comprising: an electrostatic bend for promoting a deflection of an ion beam, wherein the electrostatic bend includes a first electrode pair having a separate inner electrode and An outer electrode to allow the ion beam to pass therethrough; a second electrode pair disposed on a downstream side of the first electrode pair and having a separate inner electrode and an outer electrode to allow the ion beam to pass therebetween And a final electrode pair disposed on a downstream side of the second electrode pair and having a separate inner electrode and an outer electrode to allow the ion beam to pass therethrough. Making each of the last electrode pairs The electrode is maintained at a potential that is less than the potential held by any of the electrodes of the second electrode pair, and the electrode of the first electrode pair is maintained at a lower potential relative to the electrode of the second electrode pair. Furthermore, the internal electrodes of each of the pair of electrodes are held at a potential that is less than the potential held by the individual external electrodes of that pair of electrodes.

In some specific examples of the ion implantation system, the electrodes of the first and last electrode pairs are maintained at a first potential (V ₁ ) and the electrodes of the first and last electrode pairs are maintained at a The second potential (V ₂ ). Furthermore, the inner electrode of the second electrode pair is electrically grounded and the outer electrode of the second electrode pair is maintained at a third potential (V ₃ ). This voltage V ₁ can be more positive than this voltage V ₂ . For example, V ₁ can range from about 0V to about -30kV (negative 30kV), V ₂ can range from about 0V to about -30kV, and V ₃ can range from about 0V to about +30kV. .

In some embodiments, the ion implantation system may further include a split lens disposed on a downstream side of the electrostatic bend. The pair of cutting lenses may include a first electrode pair having a curved downstream end face and a second electrode pair having a curved upstream end face, wherein the end faces of the two electrode pairs are separated from each other to form a gap therebetween. The first and second electrode pairs are configured to be independently biasable. For example, the first and second electrode pairs are biased to create an electric field in the gap for focusing the ion beam passing through the pair of lenses.

In another aspect, an ion implantation system is disclosed that includes an electrostatic bend to receive an ion beam and deflect it, and a pair of slit lenses disposed downstream of the electrostatic bend. The pair of cutting lenses includes a first electrode pair having a curved downstream end face and a second electrode pair having a curved upstream end face, wherein the end faces of the pair of electrodes are separated from each other to form a gap therebetween. The first and second electrode pairs are configured to be independently biasable, for example, to generate an electric field in the gap for focusing the ion beam through the pair of lenses. The ion implantation system may further include an acceleration/deceleration system disposed on an upstream side of the electrostatic bend; and a mass analyzer disposed on an upstream side of the acceleration/deceleration system for receiving an ion beam and generating A mass is selected for the ion beam. In some embodiments, the electrostatic bend can include a first electrode pair, a second electrode pair, and a last electrode pair, each of which has a separate inner electrode and an outer electrode to allow the ion beam Passed in between. The three electrode pairs are configured to be independently biasable. For example, each electrode of the last electrode pair may be maintained at a potential lower than a potential held by any one of the second electrode pairs, and the electrode of the first electrode pair may also be opposite to the second electrode pair The electrode is kept at a lower potential. In some embodiments, the electrodes of the first and last electrode pairs are maintained at a first potential (V ₁ ) and the electrodes of the first and last electrode pairs are maintained at a second potential (V ₂ ). In some embodiments, V _{1 is} more positive than V ₂ . Furthermore, the inner electrode of the second electrode pair can be electrically grounded, and the outer electrode of the second electrode pair can be maintained at a third potential (V ₃ ).

Further, various aspects of the present teachings can be understood by referring to the following detailed description and related drawings. These figures are briefly described below.

10‧‧‧Ion Implantation System

12‧‧‧Ion source

14‧‧‧Extraction electrode

16‧‧‧Suppression electrode

18‧‧‧ Focusing electrode

19‧‧‧Ground electrode

20‧‧‧Analysis of magnets

20a‧‧‧Variable size mass analysis hole

22‧‧‧ Calibration System (Deceleration/Acceleration System)

24‧‧‧ Terminal Station

25‧‧‧Substrate holder

26‧‧‧Substrate

28‧‧‧Electronic gun

28a‧‧‧ Cathode

28b‧‧‧Anode

30‧‧‧Electronic gun

30a‧‧‧ cathode

30b‧‧‧Anode

32‧‧‧Ionization room

34‧‧‧ Plasma Electrode

36‧‧‧Extraction electrode

38‧‧‧Electromagnetic coil assembly

40‧‧‧slit

40a‧‧‧Gas feeder

40b‧‧‧Gas feeder

40c‧‧‧ gas feeder

40d‧‧‧ gas feeder

40e‧‧‧Gas feeder

42‧‧‧ calibration device

44‧‧‧ Controller

46‧‧‧Deceleration/acceleration components

46a‧‧‧Deceleration/acceleration electrode

46b‧‧‧Deceleration/acceleration electrode

48‧‧‧ Focusing components

48a‧‧‧Focus

48b‧‧‧Focus electrode

50‧‧‧ gap area

52‧‧‧Electrostatic elbow

52a‧‧‧External electrode

52b‧‧‧ internal electrode

52c‧‧‧Intermediate electrode

53‧‧‧ gap

54‧‧‧ calibration device

56‧‧‧ Focusing components

56a‧‧‧electrode

56b‧‧‧electrode

58‧‧‧ gap

60‧‧‧ Grounding components

60a‧‧‧Electrical grounding electrode

60b‧‧‧Electrical ground electrode

62‧‧‧ gap

100‧‧‧ Waveform Generator

102‧‧‧ Profiler

200‧‧‧Deceleration/Acceleration System

202‧‧‧slit

204‧‧‧ calibration device

206‧‧‧Deceleration/acceleration components

206a‧‧‧Electrode

206b‧‧‧Electrode

208‧‧‧ downstream focusing components

208a‧‧‧Electrode

208b‧‧‧Electrode

210‧‧‧ gap

212‧‧‧Electrostatic Bend

213‧‧‧ gap

214‧‧‧electrode pair

214a‧‧‧External electrode

214b‧‧‧ internal electrode

215‧‧‧ gap

216‧‧‧electrode pair

216a‧‧‧External electrode

216b‧‧‧ internal electrode

218‧‧‧electrode pair

218a‧‧‧External electrode

218b‧‧‧ internal electrode

219‧‧‧Internal electrode

220‧‧‧ calibration device

221‧‧‧voltage source

222‧‧‧ Focusing components

223‧‧‧voltage source

224a‧‧‧Ground electrode

224b‧‧‧Ground electrode

225‧‧‧voltage source

226‧‧‧ terminal station

227‧‧‧ Controller

228‧‧‧ wafer

300‧‧‧ implant system

302‧‧‧ hole

304‧‧‧ calibration device

306‧‧‧Deceleration/acceleration system

308‧‧‧Electrostatic elbow

308a‧‧‧Bent external electrode

308b‧‧‧Bending internal electrode

310‧‧‧pair lens

312‧‧‧electrode pair

312a‧‧‧Bending downstream end face

314‧‧‧electrode pair

314a‧‧‧Curved upstream end face

316‧‧‧Bending gap

317‧‧‧ calibration device

318‧‧‧ Focusing components

320‧‧‧Ground electrode

400‧‧‧Ion Implant System

402‧‧‧slit

404‧‧‧ calibration device

406‧‧‧Deceleration/acceleration system

408‧‧E-bend

410‧‧‧pair lens

412‧‧‧ calibration device

414‧‧‧Focus electrode

416‧‧‧Ground electrode

1100‧‧‧Ion Implant System

1200‧‧‧electrode pair

1201‧‧‧electrode pair

1202‧‧‧ internal electrode

1203‧‧‧External electrode

1204‧‧‧electrode pair

1205‧‧‧electrode pair

1206‧‧‧electrode pair

1300‧‧‧Traditional E-bend

1300a‧‧‧ internal electrode

1300b‧‧‧External electrode

1302‧‧‧electrode pair

1304‧‧‧electrode pair

1306‧‧‧electrode pair

DP‧‧‧Downstream

E1‧‧‧electrode pair

E1a‧‧‧electrode

E1b‧‧‧electrode

E2‧‧‧electrode pair

E2a‧‧‧electrode

E2b‧‧‧electrode

E3‧‧‧electrode pair

E4‧‧‧electrode pair

E4a‧‧‧electrode

E4b‧‧‧electrode

E5‧‧‧electrode pair

E6‧‧‧electrode pair

E7‧‧‧electrode pair

E8‧‧‧electrode pair

E9‧‧‧electrode pair

E10‧‧‧electrode pair

H‧‧‧Longitudinal dimensions

R1‧‧‧ radius of curvature

UF‧‧‧ upstream

UP‧‧‧Upstream

V1‧‧‧ voltage source

V2‧‧‧ voltage source

V3‧‧‧ voltage source

V4‧‧‧ voltage source

V5‧‧‧ voltage source

V6‧‧‧ voltage source

V7‧‧‧ voltage source

V8‧‧‧ voltage source

V9‧‧‧ voltage source

V10‧‧‧ voltage source

V11‧‧‧ voltage source

V12‧‧‧ voltage source

V13‧‧‧ voltage source

V14‧‧‧ voltage source

V15‧‧‧ voltage source

V16‧‧‧ voltage source

V17‧‧‧ voltage source

V18‧‧‧ voltage source

V19‧‧‧ voltage source

V20‧‧‧ voltage source

W‧‧‧ transverse size

1 schematically depicts a ribbon ion beam; FIG. 2A schematically depicts an ion implantation system in accordance with one embodiment of the present teaching; FIG. 2B is conceptually depicted in the ion implantation system of FIG. 2A. A calibration system in accordance with one embodiment of the present teachings; FIG. 2C is a schematic side cross-sectional view of a portion of the calibration system illustrated in FIG. 2B; 3A is a partial schematic view of an ion source for generating a ribbon ion beam; FIG. 3B is another partial schematic view of the ion source of FIG. 3A; FIG. 3C is another partial schematic view of the ion source of FIGS. 3A and 3B; A current profile depicting an exemplary ribbon beam produced by an ion source is depicted in accordance with the ion source illustrated in Figures 3A-3B below; Figure 5 outlines a calibration system suitable for use in one embodiment of the present teachings. Figure 6 is a schematic depiction of a ribbon ion beam through a calibration device in accordance with one embodiment of the present teachings; Figure 7A is a schematic depiction of a ribbon ion beam through a calibration device in accordance with one embodiment of the present teachings; The calibration device is configured to apply a transverse electric field to at least a portion of the ion beam; FIG. 7B schematically depicts a ribbon ion beam through a calibration device in accordance with one embodiment of the present teachings, the calibration device configuration For applying a longitudinal electric field to the ion beam to induce deflection thereof; FIG. 7C schematically depicts a ramp voltage for applying an electrode pair to the calibration device shown in FIG. 7B; FIG. 8A schematically depicts a pass The present invention is directed to a ribbon ion beam of a calibration device configured to facilitate longitudinal oscillating motion of the ion beam; FIG. 8B is a schematic depiction of a correction applied to FIG. 8A. The triangular voltage of the electrode pair of the device; FIG. 9 is a partial schematic view of the ion implantation system shown in FIGS. 2A, 2B and 2C, further depicting an ion beam profiler for determining the current profile of the ion beam; FIG. 10A depicts Correcting the analog current profile of the ribbon ion beam as a function of height; 10B shows an electrode pair to which an exemplary voltage can be applied to one of the calibration devices of the ion implantation system shown in FIGS. 2A, 2B, and 2C to provide coarse correction of the ion beam profile shown in FIG. 10A and via such The simulated profile of the partially corrected ion beam obtained by the coarse correction; FIG. 10C shows that an exemplary voltage can be applied to the electrode pair of another calibration device of the ion implantation system shown in FIGS. 2A, 2B, and 2C to improve FIG. 10B. The portion shown corrects the uniformity of the ion beam and the simulated profile of the corrected ion beam obtained in this manner; FIG. 11A outlines an ion implantation system according to a specific example in which a pair of three electrodes is used. Electrostatic bend; Figure 11B is a schematic partial view of the ion implantation system shown in Figure 11A in a dispersion plane

Figure 11C is a different schematic partial view of the ion implantation system of Figure 11A in a non-dispersive plane; Figure 11D schematically depicts a voltage source for applying a voltage to the electrodes of the electrostatic bend and a control for such The controller of the voltage source; FIG. 12A shows a theoretical simulation result of an ion beam passing through a deceleration system operating at a reduction ratio of 60 and a downstream electrostatic bend composed of two spaced electrodes; FIG. 12B shows an ion beam passing through A theoretical simulation of a deceleration system operating at a reduction ratio of 60 and a downstream electrostatic bend formed by three electrode pairs; Figure 13A shows an As ion beam with an energy of 30 keV and a current of 25 mA separated by two Theoretical simulation results of the electrostatic elbow formed by the electrode; FIG. 13B shows a theoretical simulation result of an As-ion beam having an energy of 30 keV and a current of 25 mA passing through an E-bend composed of three series electrode pairs; Figure 14A is a pair of tangent lenses having a configuration disposed downstream of an electrostatic bend a partial schematic cross-sectional view in the dispersion plane of the ion implantation system; Figure 14B is a partial schematic side view in the non-dispersing plane of the ion implantation system shown in Figure 14A; and Figure 15 is a use of a three electrode A partial schematic view of the electrostatically curved tube formed and a dispersing plane of an ion implantation system disposed downstream of the electrostatically curved tube.

In some aspects, the teachings relate to an ion implantation system (also referred to herein as an ion implanter) that includes an ion source for generating a ribbon ion beam and a means for ensuring the band The ion beam presents a correction system having a substantially uniform current density profile at least along a longitudinal dimension of the ion beam at a substrate upon which the ion beam is incident. In some cases, when the ion beam is delivered to a substrate to implant ions into the substrate, the calibration system and other optical components in the ion beam of the ion implantation system can be used to substantially maintain one A profile of the ribbon ion beam drawn from an ion source (e.g., in the range of about 5% or better).

In some embodiments, an ion implantation system in accordance with the present teachings includes an ion beam line having two stages (an ion beam implantation stage followed by an ion beam correction stage), which may optionally include one The mechanism that slows or accelerates the ion beam. This implantation phase can include ion beam generation and mass selection. In some embodiments, the ion beam correction stage can include a corrector array and a deceleration/acceleration optical element. In some embodiments, the ion beam line can be configured to implant ions into a 300-mm substrate (eg, via a ribbon-shaped ion beam of approximately 350-mm height) or a 450-mm substrate (eg, via a In a ribbon ion beam of approximately 500-mm height. For example, the ion beam line can comprise a replaceable ion optics configuration kit suitable for different substrate sizes. The ion The optical configuration kit can include, for example, an extraction electrode for extracting an ion beam from an ion source, a deceleration/acceleration stage optical element, and a substrate processing assembly in an end station of the ion implanter, for example, a replacement end effector (replacement) End effector) and FOUPs (front open wafer transfer boxes).

Various exemplary embodiments of the present teachings are described below. The terms used in these specific examples have their general meaning in the art. For the sake of clarity, the following terms are defined.

The term "ribbon ion beam" as used herein means having the largest dimension defined therein (also referred to herein as the longitudinal dimension of the ion beam) and its minimum dimension (here, also referred to as the ion). The ratio of the lateral dimensions of the bundle is an aspect ratio of the ion beam, the ratio being at least about 3, for example, equal to or greater than 10, or equal to or greater than 20, or equal to or greater than 30. A ribbon ion beam can take on a variety of different cross-sectional views. For example, a ribbon ion beam can have a rectangular or elliptical cross-sectional view. Figure 1 outlines an exemplary ribbon ion beam having a longitudinal dimension (here, also referred to as height) H and a lateral dimension (here, also referred to as width) W. Without losing its generality, in the following description of various specific examples of the invention, it is assumed that the ion beam propagates along the z-axis of the Cartesian coordinate system, the longitudinal dimension along the y-axis and the transverse dimension. Extending the x-axis. As discussed in more detail below, in these various embodiments, an analytical magnet is used to disperse the ion beam in a plane perpendicular to the direction of propagation of the ion beam. This plane is referred to herein as a dispersion plane. In the following specific example, the dispersion plane corresponds to the xz plane. A plane perpendicular to the plane of dispersion is referred to as a non-dispersive plane. In the following specific example, the non-dispersive plane corresponds to the yz plane.

As used herein, the term "current density" is used in accordance with the art of the art to mean that it flows through a unit area (eg, perpendicular to the direction of propagation of the ions). The current associated with the plasma per unit area.

The term "current density profile" as used herein means the current density of the ion beam as a function of the position along the ion beam. For example, an ion current density profile along the longitudinal dimension of the ion beam means that the ion current density is from a reference point along the longitudinal dimension of the ion beam (eg, the upper or lower edge or center of the ion beam) A function of the distance or an ion-dependent current flowing through the unit length along the longitudinal dimension.

The term "substantially uniform current density profile" means an ion current density profile that exhibits an RMS variation of up to 5%.

The term "reduction ratio" means the ratio of the energy of the ion beam entering a deceleration system to the energy of the ion beam exiting the deceleration system (ie, the energy of the ion beam received by the deceleration system and the energy of the decelerating ion beam). ratio).

Referring to Figures 2A, 2B and 2C, an ion implantation system 10 in accordance with one embodiment of the present teachings includes an ion source 12 for generating a ribbon ion beam and an electrical bias to assist the ion beam from the The ion source leads to a puller electrode 14. A suppression electrode 16 is biased with electricity to prevent neutralization electrons (eg, electrons generated by ionization of the ion beam via ambient gas) from flowing back to the ion source; biasing a focus electrode 18 with power to reduce The ion beam diverges; and a ground electrode 19 defines the reference ground of the ion beam. An analytical magnet 20 disposed on the downstream side of the focus electrode 18 receives the ribbon ion beam and produces a mass selective ion beam.

In some embodiments, the ion source housing and the analytical magnet frame assembly can be electrically isolated from the ground potential. For example, they can be floated below the ground potential at, for example, -30 kV. In some cases, the floating voltage can be selected to extract the ion beam from the ion source and to ionize the ion beam on the ion beam The energy of the energy implanted at the substrate implanted therein is subjected to mass analysis of the ion beam. In another option, the ion beam can be extracted and mass analyzed, and the ion beam can then be accelerated to be incident on the substrate at a higher energy.

Referring again to FIGS. 2A-2C, as discussed in more detail below, the exemplary ion implantation system 10 further includes a calibration system 22 for adjusting the longitudinal dimension along at least the ion beam (eg, at the ion beam) The current density profile of the ion beam in the non-dispersive plane to produce an output ribbon ion beam that exhibits a substantially uniform current density profile along at least its longitudinal dimension. Moreover, the calibration system 22 can adjust the lateral extent of the ion beam, for example, to reduce the ion beam diverging along the lateral dimension (e.g., in the dispersion plane) to ensure that the output ion beam has a desired lateral magnitude.

In some embodiments, such as discussed below, the calibration system 22 can further provide deceleration/acceleration of the mass selective ribbon beam. In this way, an output ribbon ion beam having a desired energy and a substantially uniform current density profile can be obtained. Without loss of generality, the correction system 22 is also referred to as a deceleration/acceleration system in the specific examples discussed below. However, it should be appreciated that in some embodiments, the calibration system 22 may not provide deceleration or acceleration of the ion beam.

The exemplary ion implantation system 10 further includes a terminal station 24 that includes a substrate holder for holding a substrate 26 in a path away from the ribbon beam of the calibration system 22. ) 25. In this embodiment, the substrate holder can be scanned along a dimension orthogonal to the direction of propagation of the ion beam in a manner known in the art to expose different portions of the substrate to the ion beam so that Ions are implanted therein. In some embodiments, the longitudinal dimension of the ion beam is greater than the diameter of the substrate such that linear movement of the substrate along a dimension perpendicular to the direction of propagation of the ion beam can result in implantation of ions throughout the substrate. The loss The substantial uniformity of the current density of the ribbon ion beam ensures that a uniform dose can be achieved by implanting ions across the substrate.

As the ion source 12, various ion sources capable of generating a ribbon ion beam can be used. It is described in U.S. Patent No. 6,664,547, entitled "Ion Source Ribbon Beam with Controllable Density Profile", and "Ion Source, Ion Implantation Apparatus, and Ion Implantation Method", U.S. Patent No. 7,791,041, which is incorporated herein by reference. Some examples of ion sources of the bundles are hereby incorporated by reference in their entirety in all of the above U.S. patents.

The ion source 12 used in this specific example is described in U.S. Published Application No. 2014/0265856, entitled "Magicic Field Source For An Ion Source", and entitled "Ion Source Having At Least One Electron Gun Comprising A Gas" In the entire disclosure of U.S. Patent No. 8,994,272, the entire disclosure of which is incorporated herein by reference. Briefly, referring to Figures 3A, 3B and 3C, the ion source 12 can include two opposing outer electron guns 28/30 disposed at both ends of a long and narrow rectangular ionization chamber 32 (ion source body). Each electron gun can include an indirect heated cathode (IHCs) 28a/30a and an anode 28b/30b. As shown in Fig. 3C, a plate-shaped plasma electrode 34 includes a hole shaped to allow ions to be withdrawn from the ion source (e.g., the hole may be a slit of 450 mm x 6 mm). Ion extraction is assisted by an extraction electrode 36 that is similar in shape to the plasma electrode and that is separated from the plasma electrode by one or more electrically insulating spacers (not shown). In some embodiments, the extraction electrode 36 can be biased up to -5 kV relative to the ion source body and the plasma electrode.

Referring to FIG. 3B, the ion source body is immersed in an axial magnetic field generated by the electromagnetic coil assembly 38. In this particular example, the coil assembly includes three secondary coils that are distributed along the long axis of the ion source body and that generate independent and partially overlapping magnetic fields throughout the top, middle, and bottom of the ion source body. The magnetic field limits the primary electron beam generated by the electron guns, thereby creating a well defined plasma column along the axis of the ionization chamber. The magnetic flux density produced by each of the three coil segments can be independently adjusted to ensure that there is substantially no non-uniformity in the current density of the extracted ion beam.

Referring to FIG. 3C, five individual gas feeders 40a, 40b, 40c, 40d, and 40e distributed along the long axis of the ion source body may be used to adjust the ion density along the plasma column, each of which The gas feeder has its own dedicated mass flow controller (MFC). In this embodiment, the anode and cathode of the electron gun and the plasma electrode and the extraction electrode are made of graphite. The ionization chamber is made of aluminum and its inner surface is coated with graphite.

The extracted ion beam can be analyzed by a retractable beam profiler located in the ion source housing. For a clearer expression, Figure 4 depicts the ion beam current as a function of the vertical (longitudinal) position of the ribbon ion beam produced by such a prototype ion source. The current density profile along this longitudinal dimension exhibited an RMS non-uniformity of about 2.72%.

Referring again to FIG. 2A, in this particular example, the ion beam generated by the ion source 12 is taken out and accelerated to a desired energy (eg, between 5 and 80 keV) prior to entering the analytical magnet 20. The analysis magnet 20 applies an electric field to the ion beam in the non-dispersion plane to separate ions having different mass-to-charge ratios in the dispersion plane, thereby generating a waist in the dispersion plane on the focal plane of the analysis magnet width (waist) the quality of the ion beam. As described below, a variable size mass resolving aperture 20a disposed adjacent the waist width of the ion beam allows ions having a desired mass to charge ratio to be passed downstream to the discussion discussed in more detail below. Other components of the system.

A variety of analytical magnets known in the art can be used. In this specific example, the analysis magnet has a saddle coil design of 600 mm magnetic pole gap, a bending angle of about 90 degrees, and a bending radius of 950 mm, but other magnetic pole gaps, bending angles, and bending radii may also be used. The configured variable size mass resolution aperture 20a allows ions having a desired mass to charge ratio to be delivered downstream to the deceleration/acceleration system 22. In other words, the analytical magnet 20 produces a mass selective ribbon ion beam that is received by the deceleration/acceleration system 22.

With continued reference to Figures 2A, 2B, and 2C, the deceleration/acceleration system 22 includes a slit 40 for receiving the mass selective ribbon ion beam. The slit 40 is sufficiently high to accommodate the longitudinal dimension of the ion beam, in some embodiments, the slit 40 is 600 mm high and has a range of choices (eg, between about 5 mm and about 60 mm) The transverse dimension of the continuous variation (eg, the dimension in the dispersion plane).

A correction device 42 is disposed on the downstream side of the slit 40 to receive the ribbon ion beam passing through the slit. In this particular example, as schematically illustrated in Figure 5, the calibration device 42 includes a plurality of spaced electrode pairs E1, E2, E3 stacked along the longitudinal dimension of the ion beam (i.e., along the y-axis). , E4, E5, E6, E7, E8, E9 and E10, wherein each electrode pair can be individually biased by electric power. More specifically, in this specific example, a plurality of electrostatic voltage sources V1, V2, V3, V4, V5, V6, V7, V8, V9, and V10 apply independent voltages to each electrode pair to produce a band along the band. An electric field of a component of the longitudinal dimension of the ion beam to locally cause one of the ion beams Or more partial deflection, thereby adjusting the current density profile of the ion beam along the longitudinal dimension. In this particular example, adjustment of the current density profile is performed to increase the uniformity of current density of the ion beam along its longitudinal dimension (e.g., in the non-dispersive plane). The voltage sources V1, . . . , V10 may be independent voltage sources or may be different modules of a single voltage source.

Each electrode pair includes two electrodes, for example, electrodes E1a and E1b, which are arranged substantially parallel to a plane defined by the direction of propagation of the ion beam and its longitudinal dimension. The electrodes of the electrodes are separated to provide a lateral gap through which the ion beam can pass. The electrode pair can be selected, for example, depending on the longitudinal dimension of the ion beam, the resolution required to correct for inhomogeneities in the longitudinal section of the ion beam, the type of ions in the ion beam, among other factors. The number. In some embodiments, the number of electrode pairs can be, for example, in the range of from about 10 to about 30.

The controller 44 coupled to the voltage sources V1, ..., V10 can determine the application of a voltage (e.g., a quiescent voltage) to the electrode pair of the calibration device in a manner described in greater detail below to locally pass the electrodes. A portion or more of the ion beam between one or more pairs of electrodes is biased at a selected angle thereby adjusting the current density of the ion beam along its longitudinal dimension.

For example, Figure 6 shows that the three electrode pairs E5, E6 and E7 are biased by the application of an electrostatic voltage so that the voltage applied to E6 is greater than the voltage applied to E5 and E7, and thus the shadow of the ion beam. The partially passed region produces an electric field component indicated by the arrow, the shaded portion of the ion beam exhibiting a higher charge density than the other portions of the ion beam (in this example, the other electrode pairs are maintained at the ground potential). The electric field applied to the shaded portion of the ion beam causes an upward bias of the upper portion of that portion and a downward bias of the lower portion of that portion, thereby reducing the charge density in that portion Degree to improve the uniformity of the current density profile along the longitudinal dimension.

Referring to FIG. 7A, in some embodiments, the correcting device 42 can be configured to apply a transverse electric field to the ion beam (ie, an electric field having a component along a lateral dimension of the ion beam) to facilitate the The lateral deflection of the ion beam, for example to change the direction of propagation of the ion beam. More specifically, the correction device 42 can be configured such that each of the electrode pairs can be individually biased. For example, in this specific example, voltage sources V1, . . . , V20 can each apply an independent voltage (eg, an electrostatic voltage) to the electrodes of the pair of electrodes (see, for example, voltage sources V1 and V11 are configured to apply an independent voltage to the Electrode pair E1 electrodes E1a and E1b).

For example, the potential difference between opposing electrode pairs of one or more electrodes can be selected to provide local lateral deflection of one or more portions of the ion beam. For example, as shown in FIG. 7A, in this example, the voltage sources V2 and V12 apply different voltages v2 and v12 to the electrodes E2a and E2b (v12 < v2) to facilitate passage between the two opposing electrodes. The portion of the ion beam is locally deflected toward the electrode E2b. At the same time, the voltage sources V4 and V14 apply different voltages v4 and v14 to the electrodes E4a and E4b (v14 > v4) to cause a portion of the ion beam passing between the two opposing electrodes to be locally deflected toward the electrode E4a. In some embodiments, the potential difference between the two opposing electrodes can range from about 0V to about 4kV.

In some cases, the entire ion beam can be laterally biased by applying a voltage to all of the electrodes on one side of the ion beam and another voltage to all of the electrodes on opposite sides of the ion beam, for example To change the direction of its propagation.

Referring to Figures 7B and 7C, in some embodiments, the correcting device 42 can be configured to bias the entire ion beam along the longitudinal dimension (i.e., vertically along the y-axis). For example, as shown in FIG. 7C, the controller 44 can cause the isoelectric The voltage sources V1, ..., V10 apply a ramp voltage to the pair of electrodes E1, ..., E10 to produce an electric field having a component along the longitudinal dimension of the ion beam (shown graphically in Figure 7B) It can promote the longitudinal deflection of the ion beam.

The controller 44 coupled to the voltage sources V1, ..., V20 can determine the voltage applied to the electrodes, for example, based on the desired partial or overall deflection angle of one of the ion beams. The controller can determine the desired voltage in the manner of the art, for example, based on the charge of the ions in the ion beam, a desired deflection angle. In some cases, the controller can effect voltage application to the electrodes of the pair of electrodes to provide local lateral and longitudinal deflection of the ion beam. For example, the voltage difference between different pairs of electrodes can, for example, cause local longitudinal deflection in the manner shown above with respect to Figure 6, and the voltage difference between the electrodes of the pair of electrodes can contribute to local lateral deflection.

Referring to Figure 8A, in some embodiments, the correcting device 42 can be configured to cause the ion beam to oscillate along its longitudinal dimension. The waveform generator 100 under the control of the controller 44 can apply a varying voltage to one or more pairs of the pair of electrodes to cause a longitudinal dimension along the ion beam (along the y-axis) The fluctuating electric field of the component, which in turn causes the time-varying deflection of the ion beam. In some cases, such a time varying bias of the ion beam can be in the form of a periodic oscillation of the ion beam along its longitudinal dimension. In some cases, the amplitude of such oscillations can be, for example, in the range of from about 10 mm to about 20 mm.

For example, as schematically illustrated in Figure 8B, the waveform generator can apply a triangular voltage waveform to the pair of electrodes E1, ..., E10 to cause the ion beam to periodically oscillate along its longitudinal axis. Such "wobble" of the ion beam can improve the dose uniformity of the ions implanted in the substrate incident on the ion beam. The oscillating frequency can be, for example, based on the speed of movement of the substrate relative to the incident ion beam The rate changes. In some embodiments, the oscillation frequency can be, for example, in the range of about 1 Hz to about 1 kHz.

Referring again to Figures 2A, 2B and 2C, the deceleration/acceleration system 22 further includes a deceleration/acceleration component 46 that is separated from a downstream focusing component 48 to define a gap region 50 therebetween. The deceleration/acceleration component 46 includes two opposing equipotential electrodes 46a and 46b that provide a passage therebetween for the passage of the ion beam. Similarly, the focusing element 48 includes two equipotential opposing electrodes 48a and 48b that provide a passage therebetween for the passage of the ion beam.

The application of a potential difference between the deceleration/acceleration element 46 and the focusing element 48 creates an electric field in the gap region to decelerate or accelerate the ions of the ion beam. Among other factors, it may be selected in a manner known to those of ordinary skill in the art based on the desired variation in the energy of the plasma, the type of ion of the ion beam, and the particular application of the ion beam. A potential difference between the deceleration/acceleration element and the focusing element.

For example, in some implementations, a voltage in the range of about 0 to about -30 (negative 30) kV or in the range of about 0 to about +30 (positive 30) kV can be applied to the deceleration/acceleration. Electrodes 46a/46b and voltages in the range of about 0 to about -5 (negative 5) kV can be applied to the focusing electrodes 48a/48b.

Referring to FIG. 2C, in this specific example, the upstream face (UF) of one or both of the focus electrodes 48a/48b is curved to generate an electric field component in the gap region to counteract the ion beam at the non-dispersion Divergence in the plane (along the longitudinal dimension of the ion beam). For a clearer expression, Figure 2C shows an ion beam passing through the gap 50, which exhibits the divergence of ions in the non-dispersive plane in the vicinity of its longitudinal endpoint due to the mutual exclusion space charge effect. Curved section of the upstream end of the focusing electrodes 48a/48b The face can be configured to help create an electric field pattern that applies a corrective force to such divergent ions to ensure substantially parallel propagation of ions of the ion beam. For example, the upstream end of the focusing electrode can have a generally concave cross-section (when viewed from the upstream direction) and have a radius of curvature in the range of from about 1 m to about 10 m.

Referring again to Figures 2A, 2B and 2C, the deceleration/acceleration system 22 further includes an electrostatic bend 52 disposed on the downstream side of the focusing element 48 with a gap 53 separated therefrom. A potential difference between the focusing element 48 and the electrostatic bend (e.g., one or more electrodes of the bend) can create an electric field in the gap 53 to reduce the band ion beam diverging along its lateral dimension. In other words, the gap between the focusing element 48 and the electrostatic bend 52 acts as a focusing lens for reducing the divergence of the ion beam along its lateral dimension. One or more voltage sources can be used, for example, under the control of controller 44 described above, to apply a voltage to the deceleration/acceleration component and the focusing component in a manner known in the art.

In this specific example, the electrostatic bend 52 includes an outer electrode 52a and a counter inner electrode 52b. Different potentials can be applied to the outer electrode 52a and the opposite inner electrode 52b to cause the ion beam to deflect when the ion beam passes through a lateral gap separating the electrodes. For example, the deflection angle of the ion beam can range from about 10 degrees to about 90 degrees, for example, 22.5 degrees.

In this embodiment, the static bend tube further includes an intermediate electrode 52c disposed on a downstream side of the inner electrode 52b and electrically isolated therefrom (eg, via a gap) to allow and be applied to the A voltage-independent voltage of the internal electrode 52b is applied to the intermediate electrode 52c. For example, in this specific example, the outer electrode 52a and the intermediate electrode 52c are maintained at the same potential. In some embodiments, the voltage applied to the outer electrode 52a may range from about 0 to about -20 (negative 20) kV. The voltage applied to the internal electrode 52b may be in the range of about -5 (negative 5) kV to about -30 (negative 30) kV.

The outer electrode 52a includes an upstream portion (UP) and a downstream portion (DP) that are disposed at an acute angle relative to each other to provide a curved profile for the outer electrode. Among other factors, the angle between the upstream and downstream portions of the outer electrode can be selected, for example, according to geometrical constraints, the lateral divergence of the ion beam as it enters the deceleration/acceleration system. In this specific example, the angle between the upstream portion and the downstream portion of the outer electrode is about 22.5 degrees. In this specific example, the upstream portion and the downstream portion integrally constitute the outer electrode, but in another specific example, the upstream portion and the downstream portion may be individual electrodes electrically coupled to equipotentials.

As described above, the potential difference between the outer electrode 52a and the inner electrode 52b generates an electric field in the space between those electrodes to deflect the ions of the ion beam. However, when the electrically neutral particles (neutral atoms and/or molecules) present in the ion beam (if any) have entered the electrostatic bend, they are not biased and continue to travel along their propagation direction. . As a result, these neutral particles or at least a portion thereof strikes the downstream portion (DP) of the outer electrode and are removed from the ion beam.

Another correction device 54 for adjusting the current density of the ion beam along its longitudinal dimension (in the non-dispersing plane) may optionally be disposed on the downstream side of the electrostatic bend 52. In this particular example, the correcting device 54 has a structure similar to that of the upstream correcting device 42. In particular, the correcting means 54 comprises a plurality of spaced electrode pairs, such as the electrode pairs shown in Figure 5 with respect to the upstream correcting means 42, which are stacked along the longitudinal dimension of the ion beam, each electrode pair being provided therebetween A lateral gap for the passage of the ion beam. Similar to the upstream correcting device 42, each electrode pair of the second correcting device 54 can be applied via a voltage to each electrode (eg, via a phase) Similar to the plurality of voltage sources of the voltage sources V1, ..., V10 of the correction device 42 shown in Fig. 5, they are individually biased. If desired, in this manner, the second correcting means 54 can locally bias one or more portions of the ion beam to further improve the uniformity of current density of the ion beam along its longitudinal dimension. In this manner, the two correcting devices 42 and 54 cooperatively ensure that the ribbon ion beam exiting the deceleration/acceleration system 22 exhibits high current density uniformity along its longitudinal dimension.

The controller 44 is also coupled to a voltage source for applying a voltage to the electrode pair of the second correcting device 54. The controller can determine the voltage applied to the pair of electrodes and can cause the voltage sources to apply those voltages to the pair of electrodes in a manner that is more detailed below.

Similar to the upstream correcting device 42, the second downstream correcting device 54 can be configured to cause a lateral deflection of the ion beam and/or an oscillating motion of the ion beam along its longitudinal dimension in the manner described above. Furthermore, the downstream correcting means 54 can also be configured to cause a longitudinal (vertical) deflection of the entire ion beam, for example in the manner described above with respect to the upstream correcting means 42.

As described above, in this specific example, the outer electrode 52a and the intermediate electrode 52c are maintained at the same potential. This can improve and preferably prevent undesired electric field components from causing any disturbance of the ion beam as the ion beam passes through the gap between the electrostatic bend and the second correcting device.

In this particular example, the pair of electrodes of the downstream second correcting means 54 are offset relative to the electrode pair of the upstream correcting means 42 along the longitudinal dimension of the ion beam. In other words, each electrode pair of the correcting means 54 is offset perpendicularly (along the longitudinal dimension of the ion beam) with respect to an individual electrode pair of the upstream correcting means 42. Such an offset may be, for example, one half of the longitudinal height of the electrodes of the correction devices (pixels) Half the size). In this manner, the correction devices 42 and 54 can cause local deflection of various different portions of the ion beam with a finer resolution (e.g., corresponding to a resolution of half the pixel size).

In this particular example, the correction devices 42 and 54 are suitably separated from one another to limit the voltage applied to their electrodes to less than about 2 kV, which may improve the stability of the operation of the calibration devices and may also The electrode pairs are closely aligned along the longitudinal dimension.

Although two correcting means are used in this specific example, in other embodiments only a single correcting means may be used to improve the uniformity of the current density of the ion beam along its longitudinal dimension, for example, the correcting means may be used 42 or the correction device 54. For example, in some specific examples of decelerating the ion beam received from the analysis magnet, only the downstream correction device 54 may be used.

With continued reference to FIG. 2A and FIGS. 2B and 2C, another focusing element 56 is optionally disposed on the downstream side of the second correcting device 54 and the other focusing element 56 is separated from the second correcting device 54 by a gap 58. Similar to the upstream focusing element 48, the second focusing element 56 includes a pair of opposing electrodes 56a and 56b that provide a passage therebetween for the passage of the ion beam. A potential difference between one or more electrode pairs of the second correcting means 54 and the second focusing electrodes 56a/56b causes an electric field in the gap 58 which can be reduced when the ion beam passes through the gap The ion beam diverges along its longitudinal dimension.

In some embodiments, the voltage applied to the focusing electrodes 56a and 56b can range from about 0 to about -10 (negative 10) kV.

The system further includes a grounding element 60 having a pair of opposing electrical ground electrodes 60a and 60b disposed on the second focusing electrode The downstream sides of 56a and 56b are separated from each other to form a gap 62. The opposing ground electrodes 60a and 60b form an electrically grounded duct through which the ion beam exits the deceleration/acceleration system toward the end station 24.

In some embodiments, the deceleration/acceleration system 22 lacks the second correcting device 54 and the second focusing element 58.

The potential difference between the focus electrodes 56a and 56b and the ground electrodes 60a and 60b causes the generation of an electric field component in the gap 62, which reduces the ion beam along the ion beam as it passes through the gap. The lateral dimensions are divergent. Moreover, in this specific example, for example, similar to the upstream surface (edge) of the electrodes 48a/48b, the upstream faces (edges) of the electrodes 60a and 60b are curved to reduce the ion beam along the same The longitudinal dimensions are divergent. Thus, the lens gaps 58 and 62 together provide a second focusing lens to reduce the ion beam diverging along its lateral and longitudinal dimensions.

In many embodiments, the output ribbon ion beam exiting the deceleration/acceleration system exhibits a dimension equal to or less than about 5% or equal to or less than about 4% or equal to or less than about 2% along its longitudinal dimension. A current density profile of less than about 1% RMS non-uniformity is preferred. Such a ribbon ion beam may have a longitudinal length greater than a diameter (e.g., greater than about 300 mm or greater than about 450 mm) of a substrate on which the ion beam is incident. Thus, linear movement of the substrate along the lateral dimension can result in implantation of substantially uniform doses of ions in the substrate.

In some embodiments, the output ribbon ion beam can be used to implant an ion dose in the range of about 10 ¹² to about 10 ¹⁶ cm ^-2 into a substrate. In some such embodiments, the current of the ribbon beam incident on the substrate can be, for example, at about tens of microamps (e.g., about 20 microamperes) to about tens of milliamps (e.g., about 60 millimeters). Within the range of, for example, from about 50 microamps to about 50 milliamps, or from about 2 milliamps to about 50 milliamps.

In some embodiments, the voltages applied to the calibration devices 42 and 54 can be determined in the following manner. Initially, the current density of the ribbon-shaped mass selective ion beam (also referred to herein as an uncorrected ion beam) exiting the analytical magnet 20 can be measured. For example, the uncorrected ion beam is passed through the deceleration/acceleration system 22 by applying a voltage to only the electrodes of the electrostatic bend to cause the substantially undisturbed ion beam to travel to the terminal station. .

The current density profile of the uncorrected ion beam can be measured using a current measuring device disposed in the terminal station. For example, FIG. 9 outlines a profiler 102 that is telescopically disposed in a terminal station 24 of the ion implantation system. Various beam current profilers can be used. For example, in some embodiments, the beam profiler can include a series of Faraday cups to measure the current profile of the ion beam as a function of height. In other embodiments, the ion beam profiler can include a current measurement plate that can be moved across the ion beam. The ion beam profiler is coupled to the controller 44 to provide information regarding the current profile of the ion beam along its longitudinal dimension. The controller 44 can use this information to determine the necessary voltages to apply to the calibration devices and/or other components (e.g., focusing elements). For example, the controller can use this information to determine the voltage applied to the electrode pairs of the correcting devices to improve the uniformity of the current density profile of the ion beam along its longitudinal dimension.

For example, Figure 10A shows a histogram depicting the ion current of a simulated uncorrected phosphorous ion beam with an energy of 40 keV and a total current of 30 mA in some height bins. This histogram shows local non-uniformity of the current density of the ion beam relative to a uniformity window. In this In the example, the corrected ion beam exhibits an ionic current of about 12.7% in an ion current at different height blocks.

Referring again to FIG. 9, the controller 44 can receive information about the current density profile of the uncorrected ion beam from the ion beam profiler 102 (eg, the information shown in the histogram above) and can use the information to determine The voltage applied to the pair of electrodes of one of the correcting devices (e.g., in the example shown in Figures 10A, 10B, and 10C, the downstream correcting device 54 is initially configured) to provide the ion beam along its longitudinal direction The first correction of the current density of the dimensions.

In some embodiments, the controller can compare the measured current and a reference value in each height window. If the difference between the measured current and the reference value exceeds a threshold, for example, 1 or 2 percent, the controller may cause one or more voltage sources to apply a voltage to one or more to correspond to that height window The ion beam portion passes through the pair of electrodes therebetween to bring the current in that portion closer to the reference value. As detailed above, this can be achieved by causing the ion beam to be locally deflected along its longitudinal dimension.

For example, the controller can cause a voltage source coupled to the electrode pair of the second correcting device 54 to apply the voltage shown in FIG. 10B to the pair of electrodes to defocus the ion beam at its center. And focusing the ion beam at its upper edge. For example, a voltage can be applied to pass the portion of the ion beam corresponding to the 60-90 mm height window through the electrode therebetween to reduce the current density in this portion. In this way, the uniformity of the current density of the ion beam can be improved.

The portion of the corrected ion beam corrected by one of the calibration devices (eg, the downstream correction device in this example) can then be measured, for example, in the manner described above for measuring the current density of the uncorrected ion beam in the calibration. Current density profile.

For example, the histogram shown in FIG. 10B depicts the simulated ion current as a function of a height window along the longitudinal dimension of the ion beam obtained by using only the second calibration device to improve the Correct the current density of the ion beam. This partially corrected ion beam exhibits an RMS deviation of about 3.2% of the ion beam current within the uniformity window (compared to the 12.5% variation exhibited by the uncorrected ion beam).

Referring again to Figure 9, the controller 44 can receive information regarding the current density profile of the partially corrected ion beam to determine the voltage applied to the electrode pair of the upstream correcting device 42 to further increase the uniformity of the ion beam profile. . In other words, the upstream correcting device can provide a fine correction of the ion beam profile.

For example, Figure 10C shows that a voltage can be applied to the first correcting device 42 to further increase the uniformity of the ion beam profile within the uniformity window. This figure also presents a histogram depicting the simulated profile of the beam current when using the first and second calibration devices 42 and 54 to correct the uniformity of the uncorrected ion beam having the profile shown in FIG. 10A. . This histogram shows that the combined correction effect of the two correction devices results in a current density profile with an RMS deviation of about 1.2% of the ion current within the uniformity window. In other words, in this example, the combined correction effect of the two correction devices results in an improvement in the uniformity of the current density profile of the ion beam along the longitudinal dimension by about an order of magnitude.

In other embodiments, the upstream correction device 42 can be configured to provide a coarse correction of the current density profile of the ribbon ion beam exiting the mass analyzer, and then the downstream calibration device 54 can be configured to provide the A finer correction of the current density profile of the ion beam.

As described above, the deceleration/acceleration system can be configured in a variety of different ways. System 22. For example, in some embodiments, the deceleration/acceleration voltages can be set to zero so that the system 22 acts only as a calibration system without causing deceleration and/or acceleration of ions in the ion beam.

Various ions can be implanted into various substrates using an ion implantation system in accordance with the present teachings. Some examples of ions include, but are not limited to, phosphorus ions, arsenic ions, boron ions, molecular ions like BF ₂ ⁺ , B ₁₈ H _x ^{+ ,} and C ₇ H _x ⁺ . Some examples of substrates include, but are not limited to, germanium, germanium, epitaxial (eg, polycrystalline germanium) wafers, germanium-on-insulator (SIMOX) wafers, ceramic substrates like SiC or SiN, solar cells, and in production. A substrate used in a flat panel display. Some examples of substrate shapes include circles, squares or rectangles.

In some embodiments, an electrostatic bend can be implemented by using three pairs of series electrodes disposed on the downstream side of an acceleration/deceleration system. As described in more detail below, the acceleration/deceleration system is operated in a deceleration mode to decelerate a received ion beam at a reduction ratio of at least 2 (eg, at a reduction ratio in the range of about 5 to about 100). Such an implementation of the electrostatic bend can be particularly advantageous. The term reduction ratio as used herein means the ratio of the energy of the ion beam entering the deceleration system to the energy of the ion beam exiting the deceleration system (ie, the energy of the ion beam received by the deceleration system relative to the The ratio of the energy of the decelerated ion beam).

11A, 11B, and 11C outline an ion implantation system 1100 in accordance with one such specific example. As described in more detail below, the ion implantation system 1100 is similar to the ion implantation system 10 illustrated above with respect to Figures 2A, 2B, and 2C, except that the electrostatic bend is implemented with three pairs of electrostatic bias electrodes. More specifically, similar to the ion implantation system 10 described above, the ion implantation system 1100 includes the ion source 12 for generating an ion beam; the extraction electrode 14 is electrically biased to facilitate the ion a beam is drawn from the ion source; the suppression electrode 16 is biased with electrical power to prevent neutralization electrons from flowing back; the focusing electrode 18 is biased with electricity to reduce the divergence of the ion beam; and the ground electrode 19, It defines the reference ground of the ion beam. The analysis magnet 20 is disposed on the downstream side of the focus electrode 18 to receive the ribbon ion beam and generate a mass selective ion beam.

The ion implantation system 1100 further includes a deceleration/acceleration system 200 including a slit 202 for receiving the mass selective ion beam; and a calibration device 204 similar to the above described calibration device. The deceleration/acceleration system 200 further includes a deceleration/acceleration component 206 that is separate from a downstream focusing component 208 to define a gap 210 therebetween. As described above with respect to the ion implantation system 10, the deceleration/acceleration component 206 includes two opposing equipotential electrode portions 206a and 206b that provide a passage therebetween for the passage of the ion beam. In this specific example, the electrode portions 206a and 206b are connected at their top and bottom ends to constitute a rectangular electrode. Similarly, the focusing element 208 includes two equipotential electrode portions 208a and 208b that provide a passage therebetween for the passage of the ion beam.

The application of a potential difference between the deceleration/acceleration element 206 and the focusing element 208 creates an electric field in the gap region 210 to decelerate or accelerate the ion beam. In this particular example, when operating in the deceleration mode, the potential applied between the deceleration/acceleration component 206 and the focusing component 208 can be at least a reduction ratio (eg, in the range of about 5 to about 100). Causing the ion beam to decelerate through the gap 210.

For example, to achieve a reduction ratio, a voltage in the range of about -5 kV to about -60 kV may be applied to the electrode portions 206a and 206b of the deceleration/acceleration component 206 and may be applied at about 0 V to about -30 kV (negative 30 kV). The voltage in the range of ) is to the electrode portions 208a and 208b of the focusing element 208.

In this embodiment, an electrostatic bend 212 (also referred to as E-bend 212) including three electrode pairs (214, 216, and 218) is disposed on the downstream side of the focusing element 208 to receive the ion. Beaming and deflecting the ion beam. However, when the electrically neutral particles (neutral atoms and/or molecules) present in the ion beam (if any) have entered the electrostatic bend, they are not biased and continue to travel along their propagation direction. . Similar to the previous specific example, the electrostatic bend can bias the ion beam at an angle (eg, 22.5 degrees) ranging from about 10 degrees to about 90 degrees.

The first electrode pair 124 includes an inner electrode 214b and an outer electrode 214a that are spaced apart to allow the ion beam to pass therethrough. The second electrode pair 216 also includes an inner electrode 216b and an outer electrode 216a that are spaced apart to allow the ion beam to pass therethrough. Similarly, the last electrode pair 218 includes an inner electrode 218b and an outer electrode 218a that are spaced apart to allow the ion beam to pass therethrough. At a certain angle with respect to the individual electrodes of the first and last electrode pairs (eg, half of the full deflection angle of the ion beam, the full deflection angle is, for example, a deflection in the range of about 5 degrees to about 45 degrees) Each of the electrodes of the second electrode pair is configured in an angular manner.

As described in more detail below, the electrodes of the first electrode pair 214 are maintained at a potential that is less than the potential held by the electrodes of the second electrode pair 216. Moreover, each electrode of the last electrode pair 218 is maintained at a potential lower than the potential held by any of the electrodes of the second electrode pair 216. Further, in the specific example in which the ion beam includes positively charged ions, the internal electrodes of each of the pair of electrodes are held at a potential lower than the potential held by the individual external electrodes of the pair of electrodes to generate a The electric field of the ion beam is bent as the ion beam passes between the electrodes. In other words, the inner electrode 214b is maintained at a lower potential than the outer electrode 214a, the inner electrode 216b is maintained at a lower potential than the outer electrode 216a, and the inner electrode 218b is maintained at a lower electric power than the outer electrode 218a. Bit.

More specifically, referring to FIG. 11B, in this specific example, the first electrode pair 214 outer electrode 214a and the last electrode pair 218 outer electrode 218a are maintained at the same potential (V ₁ ) and the first electrode pair 214 The inner electrode 214b and the inner electrode 218b of the last electrode pair 218 are maintained at the same potential (V ₂ ), where V _{2 is} less than V ₁ (eg, V ₂ may be -25 kV and V ₁ may be -15 kV). Note that the pair of electrodes of the second electrode 216b is electrically grounded and that the outside of the second electrode 216a of the pair of electrodes 216 held at a potential V _3, wherein V is greater than V _{3. 1} and V ₂ of each.

For example, the potential V ₁ can range from 0V (zero volts) to about -20kV, and the potential V ₂ can range from 0V (zero electrical volts) to about -30kV. Furthermore, the potential V ₃ can range from 0 to about +30 kV.

Referring to FIG 11D, in this particular embodiment, a voltage source 221 is applied to the voltage V ₁ is such electrodes 214a and 218a, 223 applies the voltage V ₂ to these electrodes 214b and 218b, and a voltage source 225 is applied to a voltage source This voltage V _{3 is} to the electrode 216a. In other embodiments, the voltage sources can apply different patterns of voltage to the electrodes. A controller 227 can control the voltage sources to apply a desired voltage to the electrodes.

The arrangement of the three electrode pairs (214, 216, and 218) can provide some advantages when used on the downstream side of a deceleration system in an ion beam line as described herein. In particular, when operating the deceleration system to provide a high reduction ratio, such as a reduction ratio greater than about 2, the ion beam can be subjected to a strong focusing effect across the deceleration gap (eg, the gap 210 described above). ). Such strong focus can produce an over-focused ion beam that can exhibit significant divergence ("blow-up") and thus strike the electrode of the bend when traversing a downstream electrostatic bend other Those electrodes of the downstream components.

The use of the segmented electrode pairs 214, 216 and 218 as the electrostatic bend can alleviate this problem. More specifically, the segmented electrode pairs 214, 216, and 218 exhibit a strong focusing ability to correct the height divergence of the ion beam caused by the deceleration system causing the ion beam to undergo intense focusing so that there is no significant loss in ions. (Preferably, without any loss) under those electrodes of the bend or other downstream components ensure that the ion beam will exit the electrostatic bend and reach the downstream wafer. For example, when the ion beam enters a gap 213 between the first electrode pair and the second electrode pair, the ion beam may be defocused. When the ion beam enters the space between the electrodes of the second electrode pair 216 and the gap 215 between the second electrode pair and the last electrode pair, the ion beam experiences a strong focusing force, but in some cases, the ion The beam will experience a small focus force in this gap 215.

For further clarity of expression, Figure 12A shows a theoretical simulation of an ion beam passing through a deceleration system and a downstream conventional electrostatic bend composed of two spaced apart electrodes. Specifically, in this specific example, the deceleration system includes two electrode pairs 1200 and 1201, wherein the electrode pair 1200 is maintained at a voltage of -29.5 kV and the electrode pair 1201 is maintained at a voltage of -5 kV. Furthermore, the inner electrode 1202 of the electrostatic bending tube is maintained at a voltage of -0.75 kV and the electrode 1203 is maintained at a voltage of -0.47 kV. In addition, it is assumed that the ion beam entering the deceleration system includes positively charged ions of energy of 30 keV. The ion beam passes through the deceleration system to reduce the energy of the ion beam to 0.5 keV. In other words, the deceleration system exhibits a reduction ratio of 60. The simulation results show that this high reduction ratio causes over-focusing of the ion beam at focus A such that the ion beam appears to cross and diverge quickly enough to strike the outer electrode and downstream components of the electrostatic bend at its distal end.

In contrast, Figure 12B shows a theoretical simulation of the ion beam passing through a deceleration system and subsequently through an electrostatic bend with three individual electrode pairs. Similar to the foregoing simulation, the deceleration system is composed of two electrode pairs 1200 and 1201 maintained at voltages of -29.5 kV and -5.5 kV, respectively. In this simulation, the electrostatic bend is implemented by using three electrode pairs 1204, 1205, and 1206 in the above manner, wherein the electrodes of the first and last electrode pairs 1204 and 1206 are maintained at a potential of -0.75 kV. And their external electrodes are maintained at a potential of -0.68 kV. The inner electrode of the second electrode pair was grounded and its outer electrode was maintained at a potential of +0.73 kV. Similar to the previous simulation, the ion beam was connected to the deceleration system with an energy of 30 keV and exited the deceleration system (corresponding to a reduction ratio of 60) with a reduced energy of 0.5 keV. Although similar to the previous simulation, the high reduction ratio causes excessive focusing of the ion beam and thus causes its divergence when the ion beam enters the electrostatic bend, but the electrostatic bend of the present teaching corrects this divergence for no ion loss. The ion beam is removed from the electrostatic bend and the downstream components, for example, under the electrodes of the electrostatic bend or the electrodes of the downstream components.

Another advantage of the electrostatic bend implemented by using the three electrode pairs described above is that it can contribute to the focusing of the high current ion beam. In the E-bend to which a high voltage is applied to the electrode of the elbow, there is usually a small amount of background electrons in the elbow. The absence of these electrons makes it difficult to neutralize the charge of the ion beam, wherein the charge neutralization can inhibit the ion beam from "spreading".

Specifically, in the conventional E-bend, since the voltage required to provide such E-bend with sufficient focusing ability is very high (for example, -30 kV to -60 kV), the problem of "spreading" of the ion beam is high. The ion beam energy (e.g., energy greater than about 30 ekV) and high ion beam current can become apparent.

For example, Figure 13A shows an energy with 30 keV and 25 mA The analog ion beam of current passes through a conventional E-bend 1300 having an inner electrode 1300a maintained at a potential of -25 kV and an outer electrode 1300b maintained at a potential of -12 kV. The ion beam has a width of 169 mm on a downstream wafer. The simulation results show that the "spread" of the ion beam causes ion loss and a wider ion beam spot on the downstream wafer, which will necessarily be larger than the wafer scan and reduced process throughput.

In contrast, FIG. 13B shows an analog ion beam having an energy of 30 keV and a current of 25 mA. According to one of the teachings E-bend, the E-bend is composed of three electrode pairs 1302, 1304 and 1306, wherein The electrodes within the pair of electrodes 1302 and 1306 are maintained at a voltage of -25 kV and those electrodes are maintained at a voltage of -13.65 kV. The inner electrode of the electrode pair 1304 is grounded and its outer electrode is maintained at a voltage of +16 kV. The simulation results show that the E-bend consisting of three individual electrode pairs prevents the ion beam from spreading and allows the ion beam to traverse the elbow and the downstream components without ion loss.

Referring again to FIGS. 11A, 11B, and 11C, in this embodiment, the electrode 218a includes an inner electrode portion 219 disposed on a downstream side of the inner electrode 218b and electrically isolated therefrom (eg, via a gap). In this embodiment, the electrode portion 219 is coupled at its top end and bottom end to the outer electrode portion of the electrode 218a to form a complete rectangular exit electrode at the exit of the E-bend. A substantially uniform potential is defined adjacent the periphery of the ribbon beam to maintain the ribbon shape of the ion beam. The ion implantation system 1100 further includes another optional calibration device 220 disposed on a downstream side of the electrostatic bend to adjust the current density of the ion beam along its longitudinal dimension (in the non-dispersive plane). Another focusing element 222 is optionally disposed on the downstream side of the second correcting device. The ion implantation system further includes opposing ground electrode portions 224a and 224b, and the opposing ground electrode portions 224a and 224b constitute an allowable The ion beam passes through an electrical grounding conduit that enters an end station 226 in which a wafer 228 is held to expose it to the ion beam.

The use of E-bend consisting of these three individual electrode pairs is not limited to ion implantation systems using ribbon ion beams. More specifically, such E-bend can also be used on the downstream side of a deceleration system in other ion implantation systems, such as circular ion beams. Another aspect of the present teachings relates to the use of one of the slit lenses disposed as an exit lens on the downstream side of one of the ion implantation systems.

For example, Figures 14A and 14B are partial schematic views of such an implant system 300. The implant system 300 similar to the implant system 10 includes a mass selective ion beam for receiving an upstream mass analyzer (not shown). Hole 302. The ion implantation system 300 further includes a calibration device 304, a deceleration/acceleration system 306 disposed on a downstream side of the calibration device 304, and an electrostatic bend 308 disposed on a downstream side of the deceleration/acceleration system. In this embodiment, the static bend bends a curved outer electrode 308a and a curved inner electrode 308b, wherein the application of a voltage difference between the electrodes causes an electric field to be generated in the space therebetween to cause an electrode at the electrodes The ion beam passing through is bent.

Unlike the ion implantation system 10 described above, in this specific example, a pair of slit lenses 310 are disposed on the downstream side of the electrostatic bending tube 308. The pair of cutting lenses 310 includes a pair of electrodes 312 and a pair of electrodes 314, wherein the pair of electrodes 312 includes a curved downstream end surface 312a and the pair of electrodes 314 includes a curved upstream end surface 314a. The two curved end faces of the pair of electrodes are separated from each other by a bending gap 316 therebetween. In some embodiments, each of the curved end faces of the lenses 312 and 314 is characterized by a radius of curvature in the range of from about 250 mm to about 1000 mm (eg, for the electrode pair 312, Displayed as R1).

The pair of electrodes 312 and 314 can be independently biased to different potentials. For example, the potential V applied to the pair of _{electrodes. 1} to ₂ and the electrode 312 may be applied to other potential V 314. If V ₁ and V ₂ are selected such that V ₁ > V ₂ , a strong vertically de-focusing lens can be formed. On the other hand, if V ₁ < V ₂ , a strong vertically focused lens can be formed. For example, the equipotentials V ₁ and V ₂ can range from about 0V to about -20kV. In some implementations, V ₁ and V ₂ may be selected to be close to ground potential (e.g., in the range of about 0 V to about -5 kV), even though the electrodes of the electrostatic bend are maintained at a higher potential. This can help reduce and better remove energy contamination when operating the ion implantation system in deceleration mode.

More specifically, in some cases, when a conventional lens is used on the downstream side of the E-bend instead of the pair of lenses, it may be necessary to apply a high voltage to the electrodes of the lens to provide a high energy ion beam (eg, Vertical focusing of an ion beam having an energy in the range of about 30 keV to 60 keV. When the ion beam passes through the lens, such a high voltage causes a temporary increase in the energy of the ion beam, which in turn causes some ions to encounter a charge exchange reaction as they traverse the lens. Because the lens is typically disposed in a straight line of sight relative to a downstream wafer, such charge exchange reactions can result in the formation of neutral atoms/molecules implanted in the downstream wafer. In addition, applying a high voltage to the electrodes of the lens can result in arc formation which can cause transient instability of the ion beam.

A pair of lenses such as the lens 310 described above can improve the vertical focusing ability of the E-bend while reducing and preferably removing ion beam contamination caused by arcing and neutral ion/molecule generation. . For example, the radius of curvature of the end face of the electrode of the pair of lenticular lenses may be sufficiently small (eg, depending on the ion velocity height, in the range of about 250 mm to about 500 mm, for example, for a 300 m high ion beam, the radius of curvature may It is about 450 mm) to allow vertical focusing/defocusing of the ion beam at lower lens voltages. For example, for the 60keV beam, V ₁ may be about -10Kv 0V and V ₂ may be, they are much lower than in the conventional lens system to reach the voltage required for focusing effect similar.

With continued reference to Figures 14A and 14B, a correction device 317 is disposed on the downstream side of the pair of cut lenses 310 to adjust the current density of the ion beam along its longitudinal dimension (in the non-dispersive plane). Another focusing element 318 can optionally be configured on the downstream side of the second correcting device. The ion implantation system further includes a ground electrode 320 constituting an electrical grounding conduit through which the ion beam can pass to enter an end station (not shown), wherein a wafer (not shown) is held in the terminal station, In order to expose it to the ion beam.

Another advantage of using the pair of slit lenses 310 is that it allows space charge neutralization to occur immediately after the correction device 317. In contrast, in a system using a conventional lens like lens 318 instead of the pair of slit lenses 310, the beginning of space charge neutralization ion beam transport may be moved deeper into the grounded conduit electrode 320, which may be high The current causes the ion beam to spread out.

A pair of tangential lenses (e.g., the above-described tangential lens 310) according to the present teachings may also be used on the downstream side of an E-bend (e.g., E-bend 212) including three electrode pairs. For example, FIG. 15 shows a partial schematic view of an ion implantation system 400 that includes a slit 402 for receiving an ion beam, a calibration device 404, a deceleration/acceleration system 406, and a E-bend 408 composed of 3 individual electrode pairs, a pair of slit lenses 410, another correcting device 412, and a cluster A focal electrode 414 and a ground electrode 416 for providing the ion beam into a conduit internally disposed at the terminal end of the wafer. The voltage applied to the electrodes of the E-bend 408 can be within the range described above with respect to the E-bend 212.

It will be apparent to those skilled in the art that various modifications can be made to the specific embodiments described above without departing from the scope of the invention.

10‧‧‧Ion Implantation System

12‧‧‧Ion source

14‧‧‧Extraction electrode

16‧‧‧Suppression electrode

18‧‧‧ Focusing electrode

19‧‧‧Ground electrode

20‧‧‧Analysis of magnets

20a‧‧‧Variable size mass analysis hole

22‧‧‧ Calibration System (Deceleration/Acceleration System)

24‧‧‧ Terminal Station

25‧‧‧Substrate holder

26‧‧‧Substrate

42‧‧‧ calibration device

46‧‧‧Deceleration/acceleration components

48‧‧‧ Focusing components

50‧‧‧ gap area

52‧‧‧Electrostatic elbow

54‧‧‧ calibration device

56‧‧‧ Focusing components

60‧‧‧ Grounding components

Claims (20)

An ion implantation system comprising: a deceleration system configured to receive an ion beam and decelerate the ion beam with a reduction ratio of at least 2; an electrostatic bend disposed on a downstream side of the deceleration system The electrostatic elbow includes: a first electrode pair disposed on a downstream side of the deceleration system for receiving the decelerating ion beam, the first electrode pair having a separation An inner electrode and an outer electrode to allow the ion beam to pass therethrough; a second electrode pair disposed on a downstream side of the first electrode pair and having an inner electrode and an outer electrode separated to allow the An ion beam passes therethrough; and a final electrode pair disposed on a downstream side of the first electrode pair and having an inner electrode and an outer electrode separated to allow the ion beam to pass therethrough, wherein the electrodes The pairs are configured to be independently biased. The ion implantation system of claim 1, wherein each electrode of the last electrode pair is maintained at a potential lower than a potential held by any one of the second electrode pairs and an electrode of the first electrode pair is opposite to the first The electrodes of the two electrode pairs are kept at a lower potential. The ion implantation system of claim 1, wherein the reduction ratio is in the range of from about 5 to about 100. The ion implantation system of claim 2, wherein the internal electrodes of each of the pair of electrodes are held at a potential that is less than a potential held by the respective outer electrodes of the pair of electrodes. The ion implantation system of claim 2, wherein the first and last electrode pairs are maintained at a first potential (V ₁ ) and the first and last electrode pairs are maintained in a second Potential (V ₂ ). The ion implantation system of claim 5, wherein the inner electrode of the second electrode pair is electrically grounded and the outer electrode of the second electrode pair is maintained at a third potential (V ₃ ). The ion implantation system of claim 5, wherein V _{1 is} higher than V ₂ . The ion implantation system of claim 1, wherein the deceleration system includes a deceleration element that is separated from a downstream focusing element to define a gap therebetween. The ion implantation system of claim 1, further comprising an ion source for generating the ion beam. The ion implantation system of claim 18, further comprising an analysis magnet disposed on a downstream side of the ion source and on an upstream side of the deceleration system for receiving the ion beam generated by the ion source and generating a mass selective ion bundle. The ion implantation system of claim 1, further comprising a pair of lenses disposed on a downstream side of the electrostatic bend, the pair of lenses comprising: a first electrode pair having a curved downstream end face; a second electrode Yes, it has a curved upstream end face in which the end faces of the two electrode pairs are separated from each other to form a gap therebetween. The ion implantation system of claim 11, wherein the first and second electrode pairs of the pair of lenses are configured to be independently biased. The ion implantation system of claim 12, wherein the first and second electrode pairs of the pair of lenses are biased to generate an electric field in the gap for focusing the ion beam through the pair of lenses . An ion implantation system comprising: an electrostatic bend tube for causing a bias of an ion beam; the static bend tube comprising: a first electrode pair having an inner electrode and an outer electrode separated to allow the ion beam to pass therebetween; a second electrode pair disposed on a downstream side of the first electrode pair and having a separation Opening an inner electrode and an outer electrode to allow the ion beam to pass therebetween; and a final electrode pair disposed on a downstream side of the second electrode pair and having an inner electrode and an outer electrode separated To allow the ion beam to pass therethrough, wherein each electrode of the last electrode pair is maintained at a potential lower than a potential held by any one of the second electrode pairs and an electrode of the first electrode pair is opposite to the second electrode The electrodes are held at a lower potential, and wherein the inner electrodes of each of the pair of electrodes remain at a potential that is less than the potential held by the individual outer electrodes of that pair of electrodes. The ion implantation system of claim 14, wherein the first and last electrode pairs are maintained at a first potential (V ₁ ) and the first and last electrode pairs are maintained in a second Potential (V ₂ ). The ion implantation system of claim 15, wherein the inner electrode of the second electrode pair is electrically grounded and the outer electrode of the second electrode pair is maintained at a third potential (V ₃ ). The ion implantation system of claim 16, wherein V _{1 is} higher than V ₂ . An ion implantation system comprising: an electrostatic bending tube for receiving an ion beam and causing a deflection of the ion beam; and a pair of slitting lenses disposed on a downstream side of the electrostatic bending tube, the pair of cutting lenses including a first electrode pair having a curved downstream end face; a second electrode pair having a curved upstream end face, wherein the first and second electrode pairs are configured to be independently biasable, and the two The end faces of the electrode pairs are separated from each other to form a gap therebetween. The ion implantation system of claim 18, wherein the first and second electrode pairs are biased to create an electric field in the gap for focusing the ion beam through the pair of lenses. The ion implantation system of claim 18, wherein the electrostatic bending tube comprises: a first electrode pair disposed on a downstream side of the deceleration system for receiving the decelerating ion beam, the first electrode pair having an inner An electrode and an outer electrode are spaced apart from each other to allow the ion beam to pass therebetween; a second electrode pair disposed on a downstream side of the first electrode pair and having an inner electrode and an outer electrode separated to Allowing the ion beam to pass therethrough; and a final electrode pair disposed on a downstream side of the first electrode pair and having an inner electrode and an outer electrode separated to allow the ion beam to pass therethrough, wherein The equal electrode pairs are configured to be independently biased.