JPH11149898A - Ion implanter - Google Patents

Abstract

(57) [Abstract] [Problem] Beam aperture B of ion implantation equipment
It is possible to reliably and accurately detect when the increase in the slit width of A reaches an alarming stage and when it reaches the allowable limit. SOLUTION: An allowable limit slit Sg having a spread allowable limit slit width is provided on a back side of a beam aperture BA.
Is formed, and on the back side thereof, a guard detection monitor aperture k is formed on which a warning guard slit Sk having a widening guard slit width is formed. Further, an ion beam is applied to the monitor apertures g and k. Detecting means 11 for detecting when it hits is provided. The detecting means 11 detects that by the electric current.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an ion implantation apparatus,
In particular, the present invention relates to an ion implantation apparatus that can eliminate a possibility that a delay in replacement of a beam aperture occurs.

[0002]

2. Description of the Related Art In the manufacture of semiconductor devices such as ICs, LSIs, and VLSIs, it is essential to implant conductive impurities such as phosphorus and boron, for which ion implantation is indispensable.
FIGS. 3A to 3C show one of conventional ion implantation apparatuses (medium current apparatus), and FIG.
(B) is a sectional view of the beam aperture, and (C) is a rear view of the beam aperture. In the drawing, reference numeral 1 denotes an ion source, which generates an ion plasma of a desired gas. For example, in the case of implanting boron ions, when BF ₃ is supplied into the ion source 1 as a gas source, the ion source 1 generates BF ₃ ion plasma.

[0003] Reference numeral 2 denotes a pre-stage accelerating electrode aperture, to which a potential such as -20 kV is applied. Ion plasma is extracted by this potential and accelerated to form a beam. Reference numeral 3 denotes an ion magnet for mass analyzing the ion beam, and electromagnetically deflects the ion beam. Since the degree of deflection is different depending on the mass of the ions, the trajectory is changed by the deflection, so that the desired ion species and the other ion species can be separated, and the target can be irradiated with only the desired ion species. It is to make.

[0004] Reference numeral 4 denotes an analysis aperture, which plays a role of passing only desired ion species and blocking other ion species. As a matter of course, the slit of the aperture 4 is located where the trajectory of the desired ion species passes,
The ion species that draws a trajectory other than the trajectory is the aperture 4
Is cut by Reference numeral 5 denotes a post-acceleration electrode, which sets the energy at the time of accelerating the ion beam and colliding with the target to a desired value. Energy can be adjusted by the voltage applied for this acceleration. Reference numeral 6 denotes a rear-stage aperture, which plays a role in shaping the spot shape of the ion beam. 7
Is an electrostatic scanner that performs scanning in the X direction and scanning in the Y direction. Specifically, two pairs of opposed electrode plates are provided,
Scanning in the X and Y directions is performed by a voltage applied between the opposing electrode plates. Reference numeral 8 denotes a scanner aperture provided at a subsequent stage of the electrostatic scanner 7, 9 denotes a mask aperture further provided at a subsequent stage, and 10 denotes a target, for example, a semiconductor wafer.

In FIGS. 3B and 3C, a indicates each of the apertures (2, 4, 6, 8, and 9), and b indicates a slit provided at the center of the aperture. Although the size differs depending on the place where it is used, FIG.
It has the shape shown in (B) and (C). That is, it has a shape that merely has a shape in which a slit b for passing an ion beam is provided in the center of the disk-shaped body. The material generally consists of carbon. The aperture a often plays a role in shaping the spot shape of the ion beam, but sometimes plays a role in blocking a beam deviated from the target 10.

Meanwhile, the slit width of each aperture a increases due to the collision of the ion beam and changes with time.
When the width of the slit is increased, the width of the spot of the ion beam is also increased. Therefore, there is a possibility that troubles due to discharge occur frequently and insulation failure accidents occur frequently. this is,
It is not preferable because the downtime of the ion implantation apparatus increases, the uniformity of the ion implantation decreases, the variation in the ion implantation amount increases, and the metal contamination increases.

[0007] Further, an increase in the slit width of the aperture a causes a decrease in the beam resolution, which causes undesired ion species mixing and energy contamination, which is not preferable.

Therefore, it is necessary to replace the aperture a immediately after the width of the slit b exceeds the allowable expansion range. And, in the past, generally how to emit the beam,
If there is an abnormality by observing the beam waveform, it is possible to prevent the abnormality caused by the expansion of the slit width by suspecting the expansion of the slit width as one of the causes of the abnormality, or by replacing the aperture a at the time of periodic maintenance. Was being planned.

[0009]

However, there was a problem with that. That is, the judgment of the slit width based on the beam appearance and the beam waveform is a so-called secondary parameter judgment, and there is an individual difference in the judgment.
This is because it is difficult to make an unambiguous determination, and it is impossible to accurately confirm the slit width unless the vacuum chamber of the ion implantation apparatus is opened and visually observed.

In order to prevent a trouble caused by an increase in the slit width in the form of replacing the aperture at the time of periodic maintenance, the maintenance cycle is shortened so that the replacement is performed before the slit width of the aperture reaches an allowable range. Must be set. Actually, the maintenance cycle of the vacuum system of the ion implantation apparatus is set based on the aperture replacement cycle. However, this means that the replacement is performed at a different time from the time when the replacement must actually be performed, so that the maintenance is brought forward. Therefore, productivity is reduced.

The present invention has been made in order to solve such a problem, and it is possible to reliably and accurately determine when the width of the slit width of the beam aperture has reached a warning stage and when it has reached an allowable limit. The purpose is to enable detection.

[0012]

According to a first aspect of the present invention, there is provided an ion implantation apparatus, further comprising: a limit detection monitor aperture having a permissible limit slit having a spread permissible limit slit width formed on the back side of the beam aperture. Is provided with a monitor aperture for alert detection in which a spreading alert slit having an alert slit width is formed, and a detecting means for detecting when a beam hits each monitor aperture.

Therefore, according to the ion implantation apparatus of the present invention, when the slit width of the beam aperture exceeds the alert slit width, the ion beam is irradiated to the alert detection monitor aperture, which is detected by the detecting means. Accordingly, it is possible to recognize from the detection result that the time to replace the beam aperture is approaching, and at that time, it is only necessary to be in a state of alert such as preparation for replacement.

When the slit width of the beam aperture exceeds the permissible limit, the ion beam is also irradiated to the limit detection monitor aperture, which is detected by the detection means. Therefore, it is possible to recognize from this detection result that it is time to exchange the beam aperture. In this case, the operation of the ion implanter may be immediately stopped, and the beam aperture may be replaced.

[0015]

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a limit detection monitor aperture having a permissible limit slit having a spread permissible limit slit width formed on the back side of a beam aperture, and a warning slit on the back side of the monitor aperture. A monitor aperture for alert detection with a widened alert slit is provided, and a detection means for detecting when an ion beam hits the monitor aperture is provided.A monitor aperture for limit detection and a monitor aperture for alert detection May be provided for all the beam apertures in the ion implantation apparatus, or may be provided only for some of the beam apertures. The material may be, for example, carbon, but may be another material as long as the irradiation of the ion beam can be detected.

As a means for detecting when the monitor aperture is irradiated with the ion beam, a current detection circuit for grounding the monitor aperture through current detection means such as an ammeter is preferable. This is because, when the ion beam is irradiated, a current corresponding to the irradiation amount flows through the current detection circuit, and the current is detected by the current detection means. Such detection means may be provided one by one corresponding to the limit detection monitor aperture and the alert detection monitor aperture, but one detection means is provided for both of them, and one detection means is switched. Thus, it may be used to detect both the irradiation of the ion beam to the alert detection monitor aperture and the detection of the irradiation of the ion beam to the limit detection monitor aperture. Also, beware of multiple beam apertures,
The detection of the limit may be performed by one detecting means, for example, in a time-division manner.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. 1A to 1D show a first embodiment of the ion implantation apparatus according to the present invention, wherein FIG. 1A is a schematic configuration diagram of the ion implantation apparatus, FIG. 1B is a beam aperture, a limit monitor aperture, and FIG. FIG. 3C is a cross-sectional view showing a security monitor aperture, FIG. 4C is a rear view showing a beam aperture, a limit monitor aperture and a security monitor aperture, and FIG. 4D is a front view showing the beam aperture and a security monitor aperture. In the drawing,
Reference numeral 1 denotes an ion source which generates an ion plasma of a desired gas. For example, when boron ions are implanted, B
When F ₃ is supplied as a gas source into the ion source 1, ion plasma of BF ₃ is generated from the ion source 1.

Reference numeral 2 denotes a pre-acceleration electrode aperture to which a potential of, for example, -20 kV is applied. By this potential, ion plasma is extracted and accelerated to form a beam. Reference numeral 2g denotes a limit monitor aperture provided immediately after the pre-acceleration electrode aperture, and 2k denotes a warning monitor aperture provided immediately after the limit monitor aperture 2g. The structure and significance of the limit monitor aperture 2g and the alert monitor aperture 2k will be clarified later.

The limit monitor aperture 3 is an ion magnet for mass analyzing the ion beam, and electromagnetically deflects the ion beam. This makes the trajectory of deflection different because the degree of deflection differs depending on the mass of the ions,
Thereby, a desired ion species is separated from other ion species, and only the desired ion species is irradiated on the target.

Reference numeral 4 denotes an analysis aperture, which passes only desired ion species, blocks other ion species, and shapes a beam spot. As a matter of course, the slit of the aperture 4 is provided at a position where the trajectory of the desired ion species passes, and the ion species that draws a trajectory other than the trajectory is cut by the aperture 4. 4g is a limit monitor aperture provided immediately after the analysis aperture, and 4k is a warning monitor aperture provided immediately after the limit monitor aperture 4g. The configurations and the significance of the limit monitor aperture 4g and the alert monitor aperture 4k will be clarified later.

Reference numeral 5 denotes a post-stage accelerating electrode for setting the energy at the time of accelerating the ion beam and colliding with the target to a desired value. Energy can be adjusted by the voltage applied for this acceleration. Reference numeral 6 denotes a rear-stage aperture, which plays a role in shaping the spot shape of the ion beam. 6g is the limit monitor aperture provided immediately after the latter aperture, and 6k is the limit monitor aperture 6
This is a security monitor aperture provided immediately after g. The structure and significance of the limit monitor aperture 6g and the alert monitor aperture 6k will be clarified later.

Reference numeral 7 denotes an electrostatic scanner which performs scanning in the X direction and scanning in the Y direction. Specifically, two pairs of opposed electrode plates are provided, and scanning in the X and Y directions is performed by applying a voltage between the opposed electrode plates. 8 is the electrostatic scanner 7
Is a scanner aperture provided at the subsequent stage, 8g is a limit monitor aperture provided immediately after the scanner aperture, and 8k is a warning monitor aperture provided immediately after the limit monitor aperture 8g. The structure and significance of the limit monitor aperture 8g and the alert monitor aperture 8k will be clarified later.

Reference numeral 9 denotes a mask aperture provided at a subsequent stage, and reference numeral 10 denotes a target, for example, a semiconductor wafer. S1 and S2 are changeover switches. The changeover terminal of S1 is connected to the limit monitor aperture k, and the changeover terminal of S2 is connected to the warning monitor aperture g.
Reference numeral 11 denotes an ammeter which is connected between the common terminal of the switching terminal switches S1 and S2 and the ground, and has a limit monitor aperture k or an alert monitor aperture g.
When the ion beam is irradiated on the sample, the current flowing between the sample and the ground is measured. Thus, when the limit monitor aperture k or the alert monitor aperture g is irradiated with the ion beam, it can be detected.

The present ion implantation apparatus is different from the conventional ion implantation apparatus shown in FIG.
As shown in FIGS. 1B to 1D, a limit monitor aperture g and an alert monitor aperture k are provided on the rear side of the beam aperture BA for every 8 and 9 respectively, and a limit monitor aperture g and an alert monitor are provided. The only difference is that when the monitor aperture k is irradiated with the ion beam, the fact is detected.

The limit monitor aperture g immediately behind the beam aperture BA is disk-shaped, has a permissible limit slit Sg extending in the center, and the slit width is larger than the initial value of the width of the slit Sa of the beam aperture BA. Is also set to the limit width at which the spread is allowed to be large, that is, the allowable slit width of the spread. The alert monitor aperture k immediately behind the limit monitor aperture g has an alert slit Sk that extends in the center and has an alert slit Sk that is wider than the initial value of the width of the slit Sa of the beam aperture a. The width of the slit is greater than the allowable slit width.

The width of the allowable limit slit Sg, that is, the allowable limit slit width is set, for example, to a value when the beam resolution reaches the allowable limit value. In addition, security slit Sk
Of the beam aperture BA
The time required for the width of the slit to widen from the width (alert slit width) to the allowable limit slit width is set with an appropriate margin in consideration of the time required for preparation for replacement and the like. The center of the slits Sg and Sk of the limit monitor aperture g and the alert monitor aperture k match the center of the slit Sa, and the slits Sg and S
They are arranged such that the direction of k and the direction of the slit Sa match. This is referred to as slit alignment in this specification.

In such an ion implantation apparatus, it is always automatically monitored whether or not the expansion of the slit width of each beam aperture BA has entered the alert stage, and whether or not the allowable limit has been reached after the alert stage. can do. That is,
Each beam aperture BA has its slit S at the beginning of the exchange.
Although the width of “a” is narrow, the width of the slit Sa is increased by spattering by repeating the ion implantation. Until it reaches the above-mentioned guard slit width, the ion beam does not strike the guard monitor aperture k as well as the limit monitor aperture g. This is because the limit monitor aperture g and the alert monitor aperture k are hidden behind the beam aperture BA.

However, when the width of the slit Sa exceeds the width of the alert slit, the ion beam is irradiated on the alert monitor aperture k. Then, a current flows through the ammeter 11 when the switch S1 is turned on. Thus, the switch S1
When a current flows through the ammeter 11 when the switch is turned on, a warning is issued to the effect that the time to replace the beam aperture BA is approaching. When such an alarm is issued, the operator of the ion implanter operates the beam aperture B.
It is sufficient to prepare for the exchange of A.

When the width of the slit Sa exceeds the alert slit width and the width of the slit Sa exceeds the allowable limit slit width, the ion beam is also irradiated to the limit monitor aperture g. Then, a current flows through the ammeter 11 when the switch S2 is turned on. As described above, when the current is detected by the ammeter 11 when the switch S2 is turned on, an alarm notifying that the allowable limit has been reached is issued. Then, the operator of the ion implanter receiving the alarm immediately stops the operation of the ion implanter. Alternatively, the operation stop program may be automatically executed and stopped. And beam aperture BA
Perform various maintenance including replacement of

According to such an ion implantation apparatus, it is determined whether or not the width of the slit Sa of the beam aperture BA has reached the alert stage, whether or not the allowable limit has been reached from the alert stage, in other words, whether or not the slit has increased. The slit width can be monitored in real time based on the data of the primary parameter relating to the width. Therefore, there is no problem that the judgment result is different depending on the operator as in the case of checking the slit width based on the data of the conventional secondary parameter. That is, the determination result can be uniquely determined.

Further, the town time of the ion implantation apparatus can be greatly reduced as compared with the conventional case, and therefore, the productivity can be improved. That is, the frequency of the periodic maintenance after opening the vacuum chamber of the ion implanter is performed in consideration of the degree of the temporal change of the slit width of the beam aperture a, that is, the temporal change of the slit width corresponds to the periodic maintenance cycle. Although the rate was limited and set appropriately with allowance, the present ion implanter allows real-time monitoring of the slit width, so that the beam aperture BA is replaced only when replacement is actually required. Can greatly reduce the frequency of maintenance. This naturally leads to an increase in productivity.

In addition, real-time monitoring and management of the slit width can be managed in multiple stages such as a warning stage and a limit stage. In addition, the point of the alert stage and the limit stage of the slit width can be arbitrarily set according to the required specifications on the process / device by the width of the slits Sg and Sk of the limit monitor aperture g and the alert monitor aperture k. it can.

Since the detection of the irradiation of the ion beam to the alarm monitor aperture k or the limit monitor aperture g is performed by current detection, it can be performed very easily. However, the detection of the current does not necessarily have to be performed by the ammeter, and any means may be used as long as the current can be detected. Therefore, it is not always necessary to use an instrument such as an ammeter (or a voltmeter). For example, various modes such as interposing a resistor in a path of current flow by the ion beam, comparing a voltage drop at a part of the resistor with a reference value, and issuing an alarm when the voltage drop is higher than the reference value, etc. possible.

FIG. 2 is a sectional view showing a main part of a second embodiment of the ion implantation apparatus of the present invention. In the drawing, reference numeral 12 denotes a socket, which is attached to the back surface of the beam aperture BA, and 13 denotes an insulator constituting the socket 12, 1
Reference numeral 4g denotes a storage unit for detachably storing the limit monitor aperture g, and reference numeral 14k denotes a storage unit for detachably storing the warning monitor aperture k. The storage section 14g, 1
4k is the beam aperture BA in a state where the insulator 13 and the beam aperture BA are insulated from each other.
When the limit monitor aperture g and the alert monitor aperture k are stored in the storage portions 14g and 14k of the socket 12, the slits Sg and Sk are slits Sa of the beam aperture BA.
It is adapted to match. There are several types of dimensions and aspect ratios (aspect ratios) of the slits Sg and Sk, and various slit widths. In any case, alignment can be performed in a state where the slits are aligned by the socket 12 in any case. Therefore, it is possible to suppress a variation in alignment at the time of replacement maintenance of the beam aperture BA.

[0035]

According to the ion implantation apparatus of the first aspect, when the slit width of the beam aperture exceeds the alert slit width, the ion beam is irradiated to the alert detection monitor aperture, which is detected by the detecting means. Therefore, it is possible to recognize from the detection result that the time to replace the beam aperture is approaching, and to start preparations for the replacement accordingly.

When the slit width of the beam aperture exceeds the permissible limit, the ion beam is also irradiated to the limit detection monitor aperture, and this is detected by the detection means. Therefore, it is possible to recognize from the detection result that the time has come to exchange the beam aperture. Accordingly, the operation of the ion implantation apparatus may be stopped immediately and the beam aperture may be replaced.

According to the ion implantation apparatus of the first aspect, as is apparent from the above description, the slit width can be monitored in real time based on the data of the primary parameter relating to the slit width. There is no problem that the judgment result differs depending on the operator as in the case of checking the slit width based on the data of the secondary parameter. That is, the determination result can be uniquely determined.

Further, the town time of the ion implantation apparatus can be greatly reduced as compared with the conventional case, and therefore, the productivity can be improved. That is, the period and frequency of the periodic maintenance after opening the vacuum chamber of the ion implanter are set in consideration of the degree of the temporal change of the slit width of the beam aperture, that is, the temporal change of the slit width determines the periodic maintenance period. However, according to the present ion implantation apparatus, the slit aperture can be monitored in real time, so that the beam aperture can be replaced only when the replacement is actually required. And the frequency of maintenance can be greatly reduced.

In addition, the real-time monitoring and management of the slit width can be managed in multiple stages such as a warning stage and a limit stage. In addition, the points of the alert stage and the limit stage of the slit width can be arbitrarily set according to the required specifications of the process / device by the limit monitor aperture and the slit width of the alert monitor aperture.

According to the ion implantation apparatus of the second aspect, by setting the limit monitor aperture and the warning monitor aperture in the socket, it is possible to automatically align and attach the beam aperture to the beam aperture. Therefore, the limit monitor aperture and the alert monitor aperture can be attached to the beam aperture without any variation in alignment.

[Brief description of the drawings]

FIGS. 1A to 1D show a first embodiment of the ion implantation apparatus of the present invention, in which FIG. 1A is a schematic configuration diagram, and FIG.
Is a cross-sectional view of the beam aperture, the limit monitor aperture and the alert monitor aperture, (C) is a rear view of the beam aperture, the limit monitor aperture and the alert monitor aperture, and (D) is a beam aperture, the limit monitor aperture and alert. FIG. 2 is a front view of the monitor aperture for use.

FIG. 2 is a sectional view showing a main part of a second embodiment of the ion implantation apparatus of the present invention.

FIGS. 3A to 3C show one of conventional ion implantation apparatuses (medium current apparatus), and FIG.
(B) is a sectional view of the beam aperture, and (C) is a rear view of the beam aperture.

[Explanation of symbols]

BA (2, 4, 6, 8, 9) ... beam aperture, g (2 g, 4 g, 6 g, 8 g, 9 g) ... monitor aperture for limit, k (2 k, 4 k, 6 k, 8 k,
9k) ・ ・ ・ Alarm monitor aperture, Sa ・ ・ ・
Slit of beam aperture, Sg: allowable limit slit, Sk: warning slit, 11: current detecting means, 12: socket.

Claims (2)

[Claims] 1. A limit detection monitor aperture, in which a spreading allowable limit slit having a spreading allowable limit slit width wider than an initial slit width of the aperture slit is formed on a back surface side of a beam aperture in which an aperture slit is formed. Provided so that the permissible limit slit is aligned with the aperture slit, and on the back side of the limit detection monitor aperture, has a perceived slit width that is appropriately smaller than the permissible limit slit width and wider than the initial slit width of the aperture slit. A warning detection monitor aperture having a spreading warning slit is provided, and a detection means for detecting when the beam hits the limit detection monitor aperture and the warning detection monitor aperture is provided. On the injection device. 2. A supporting portion for supporting a limit detection monitor aperture in a state in which it is electrically insulated from the beam aperture, and a warning monitor aperture is electrically connected to the beam aperture and the limit detection monitor aperture on the back surface of the beam aperture. 2. The ion implantation according to claim 1, further comprising a socket having a supporting portion for supporting the monitor aperture in a state of being insulated, wherein the socket supports the monitor aperture for limit detection and the monitor aperture for alert. apparatus.