JP5851681B2 - Plasma processing equipment - Google Patents

Description

The present invention relates to a technique for performing a plasma process on a target substrate, more particularly to inductively coupled plasma processing apparatus.

  In processes such as etching, deposition, oxidation, sputtering and the like in the manufacturing process of semiconductor devices and FPDs (Flat Panel Displays), plasma is often used in order to cause a favorable reaction to a processing gas at a relatively low temperature. Conventionally, plasma of high frequency discharge in the MHz region is often used for this type of plasma processing. Plasma by high frequency discharge is roughly classified into capacitively coupled plasma and inductively coupled plasma as more specific (device-like) plasma generation methods.

  In general, an inductively coupled plasma processing apparatus is configured such that at least a part (for example, a ceiling) of a wall of a processing container is formed of a dielectric window, and a high frequency power is applied to a coiled RF antenna provided outside the dielectric window. Supply. The processing container is configured as a vacuum chamber that can be depressurized, and a processing space is set between the dielectric window and the substrate in which a substrate to be processed (for example, a semiconductor wafer, a glass substrate, etc.) is disposed in the center of the chamber. A processing gas is introduced into the system. The RF current flowing through the RF antenna generates an RF magnetic field around the RF antenna so that the magnetic lines of force pass through the dielectric window and pass through the processing space in the chamber. An induced electric field is generated in the azimuth direction. Then, the electrons accelerated in the azimuth direction by the induced electric field cause ionization collision with the molecules and atoms of the processing gas, and a donut-shaped plasma is generated.

  By providing a large processing space in the chamber, the doughnut-shaped plasma is efficiently diffused in all directions (particularly in the radial direction), and the density of the plasma is fairly uniform on the substrate. However, using only a normal RF antenna, the plasma density uniformity obtained on the substrate is insufficient for most plasma processes. Even in the inductively coupled plasma processing apparatus, improving the uniformity of the plasma density on the substrate is one of the most important issues because it affects the uniformity and reproducibility of the plasma process and, in turn, the manufacturing yield. So far, several related techniques have been proposed.

  Conventional typical plasma density equalization techniques divide the RF antenna into a plurality of segments. This RF antenna division method includes a first method (for example, Patent Document 1) that supplies individual high-frequency power to each antenna segment, and the impedance of each antenna segment is varied by an additional circuit such as a capacitor. There is a second method (for example, Patent Document 2) that controls the division ratio of RF power distributed to all antenna segments from one high-frequency power source.

  Further, a technique (Patent Document 3) in which a single RF antenna is used and a passive antenna is disposed in the vicinity of the RF antenna is also known. This passive antenna is configured as an independent coil that is not supplied with high-frequency power from a high-frequency power source, and simultaneously reduces the magnetic field strength in the loop of the passive antenna against the magnetic field generated by the RF antenna (inductive antenna). It behaves so as to increase the magnetic field strength near the outside of the loop of the passive antenna. As a result, the radial distribution of the RF electromagnetic field in the plasma generation region in the chamber is changed.

US Pat. No. 5,401,350 US Pat. No. 5,907,221 Special table 2005-534150

  However, among the RF antenna division methods as described above, the first method requires not only a plurality of high-frequency power sources but also the same number of matching units, which is a bottleneck due to the complexity of the high-frequency power feeding unit and the significant cost increase. ing. In the second method, the impedance of each antenna segment is affected not only by the other antenna segments but also by the plasma impedance. Therefore, the division ratio cannot be arbitrarily determined only by the additional circuit, and the controllability It is difficult to use.

  Further, the conventional method using a passive antenna as disclosed in Patent Document 3 affects the magnetic field generated by the RF antenna (inductive antenna) due to the presence of the passive antenna, thereby causing a plasma generation region in the chamber to be generated. Although it is taught that the radial distribution of the RF electromagnetic field can be changed, the consideration and verification of the action of the passive antenna is insufficient, and the passive antenna can be used to freely and accurately control the plasma density distribution. I cannot imagine the specific device configuration.

  Today's plasma processes require lower-pressure, higher-density, and larger-diameter plasma as the substrate becomes larger and devices become finer, and process uniformity on the substrate is more difficult than ever. It has become an issue.

  In this regard, the inductively coupled plasma processing apparatus generates a plasma in a donut shape inside a dielectric window close to the RF antenna, and diffuses the donut plasma toward the substrate in all directions. The plasma diffusion form changes depending on the pressure in the chamber, and the plasma density distribution on the substrate tends to change. Therefore, even if the pressure is changed in the process recipe, the magnetic field generated by the RF antenna (inductive antenna) cannot be corrected so that the uniformity of the plasma density on the substrate can be maintained following the change. The diverse and advanced process performance required for today's plasma processing equipment cannot be met.

The present invention has been made in view of the prior art as described above, and does not require any special work on the RF antenna for plasma generation or the high-frequency power feeding system, and the plasma density distribution using a simple correction coil. An inductively coupled plasma processing apparatus is provided that can be controlled freely and finely.

  A plasma processing apparatus according to a first aspect of the present invention includes a processing container having a dielectric window, a coiled RF antenna disposed outside the dielectric window, and a substrate to be processed in the processing container. A substrate holding unit, a processing gas supply unit for supplying a desired processing gas into the processing container, and a plasma of the processing gas generated by inductive coupling in the processing container to perform a desired plasma process on the substrate. In order to control the plasma density distribution on the substrate in the processing container, the RF antenna for supplying the RF antenna with a high frequency power having a frequency suitable for the high frequency discharge of the processing gas, A correction coil disposed outside the processing container at a position where it can be coupled by electromagnetic induction, a switching element provided in a current path of the correction coil, and the switching element And a switching control unit for controlling on / off by the pulse width modulation in the duty ratio.

  In the plasma processing apparatus according to the first aspect, high-frequency power is supplied from the high-frequency power feeding unit to the RF antenna by the above-described configuration, particularly by the configuration including the correction coil, the switching element, and the switching control unit. Sometimes the correction coil acts on the RF magnetic field generated around the antenna conductor by the high-frequency current flowing through the RF antenna (the effect of locally reducing the density of the core plasma generated by inductive coupling around the position overlapping the coil conductor) ) In a typical and stable manner. Furthermore, the degree of such a correction coil effect (an effect of locally reducing the density of the core plasma) can be controlled substantially linearly. This makes it possible to arbitrarily and finely control the plasma density distribution in the vicinity of the substrate on the substrate holding unit, and to easily improve the uniformity of the plasma process.

A plasma processing apparatus according to a second aspect of the present invention includes a processing container having a dielectric window on a ceiling, a coiled RF antenna disposed on the dielectric window, and a substrate to be processed in the processing container. A substrate holding portion for holding the substrate, a processing gas supply portion for supplying a desired processing gas into the processing vessel in order to perform a desired plasma treatment on the substrate, and a plasma of the processing gas by inductive coupling in the processing vessel. to generate, for controlling said high frequency power RF antenna supplying RF supply section of frequencies for the radio frequency discharge of the processing gas, the plasma density distribution on the substrate in the processing chamber, the opposite ends a coil conductor annular is open with a gap, distribution over the RF antenna in the radial direction bondable position by electromagnetic induction between the inner and outer peripheries of said RF antenna It is the a correction coil, and a variable resistor provided in the gap of the correction coil and a resistance control unit that controls the resistance value of the variable resistor to a desired value.

  In the plasma processing apparatus according to the second aspect, high-frequency power is supplied from the high-frequency power feeding unit to the RF antenna by the above-described configuration, particularly by the configuration including the correction coil, the variable resistor, and the resistance control unit. Sometimes the correction coil acts on the RF magnetic field generated around the antenna conductor by the high-frequency current flowing through the RF antenna (the effect of locally reducing the density of the core plasma generated by inductive coupling around the position overlapping the coil conductor) ) In a typical and stable manner. Furthermore, the degree of such a correction coil effect (an effect of locally reducing the density of the core plasma) can be controlled substantially linearly. This makes it possible to arbitrarily and finely control the plasma density distribution in the vicinity of the substrate on the substrate holding unit, and to easily improve the uniformity of the plasma process.

A plasma processing apparatus according to a third aspect of the present invention includes a processing container having a dielectric window , an RF antenna disposed outside the dielectric window, and a substrate holding unit for holding a substrate to be processed in the processing container. In order to perform a desired plasma processing on the substrate, a processing gas supply unit that supplies a desired processing gas into the processing container, and a plasma of the processing gas by inductive coupling in the processing container, In order to control the plasma density distribution on the substrate in the processing container, a high-frequency power supply unit that supplies high-frequency power having a frequency suitable for high-frequency discharge of the processing gas to the RF antenna, and a loop independent of the RF antenna is provided. a, chromatic correction coil disposed outside the processing container bondable position by electromagnetic induction and the RF antenna, and a switch provided in the loop of the correction coils The correction coil is composed of a single-turn coil or a double-turn coil closed at both ends, and is arranged coaxially with the RF antenna, and the coil conductor is positioned between the inner periphery and the outer periphery of the RF antenna in the radial direction. The coil diameter is as follows.

In the above-described third plasma processing apparatus according to aspect, the configuration described above, in particular by the configuration and a the correction coil and the switch and the correction coil, single-turn coil or multiple-turn coil closed at both ends, consists, is disposed coaxially with respect to the RF antenna, the coil conductor in the radial direction by the configuration having a coil diameter such as to be located between the inner and outer peripheries of said RF antenna, RF from the high-frequency power supply unit Action of the correction coil against the RF magnetic field generated around the antenna conductor by high-frequency current flowing through the RF antenna when high-frequency power is supplied to the antenna (the density of the core plasma generated by inductive coupling around the position overlapping the coil conductor) Can be selectively obtained.

A plasma processing apparatus according to a fourth aspect of the present invention includes a processing container having a dielectric window, which can be evacuated, an RF antenna disposed outside the dielectric window, and a substrate to be processed in the processing container. A substrate holding unit, a processing gas supply unit for supplying a desired processing gas into the processing container, and a plasma of the processing gas generated by inductive coupling in the processing container to perform a desired plasma process on the substrate. In order to control the plasma density distribution on the substrate in the processing container, and the RF antenna for controlling the plasma density distribution on the substrate in the processing container respectively. A first correction coil and a second correction coil disposed outside the processing container at a position that can be coupled to the RF antenna by electromagnetic induction, and the first and second correction coils. It has a first and second switches respectively provided beauty the second correction coil loop, the dielectric window constitutes the ceiling of the processing container, wherein the RF antenna is on the dielectric window The first and second correction coils are arranged in parallel with the RF antenna, and the first and second correction coils are arranged concentrically.

In the plasma processing apparatus according to the fourth aspect, the above-described configuration, in particular, the configuration including the first and second correction coils and the first and second switches, and the dielectric A window constitutes the ceiling of the processing container, the RF antenna is disposed on the dielectric window, the first and second correction coils are disposed in parallel with the RF antenna, and the first and second With the configuration in which the correction coils are concentrically arranged, the action of each correction coil on the RF magnetic field generated around the antenna conductor by the high-frequency current flowing through the RF antenna when high-frequency power is supplied from the high-frequency power feeding unit to the RF antenna It is possible to selectively obtain (the effect of locally reducing the density of the core plasma generated by inductive coupling around the position overlapping the coil conductor). , More may be selected first correction coils combined with correction coils entire mode of action of the second correction coils (profile) great variety.

  According to the plasma processing apparatus or the plasma processing method of the present invention, with the above-described configuration and operation, a simple correction coil is used without requiring any special work on the RF antenna for generating plasma or the high-frequency power feeding unit. The plasma density distribution can be freely and finely controlled.

It is a longitudinal cross-sectional view which shows the structure of the inductively coupled plasma processing apparatus in the 1st Embodiment of this invention. It is a perspective view which shows an example of RF antenna of a spiral coil shape. It is a perspective view which shows an example of a concentric coil-shaped RF antenna. It is a figure which shows typically an example of an electromagnetic effect when a perfect endless type correction coil is arranged far away from the RF antenna. It is a figure which shows typically an example of an electromagnetic effect when arrange | positioning a perfect endless type | mold correction coil near RF antenna. It is a figure which shows typically another example of the electromagnetic effect | action when a complete endless type | mold correction coil is arrange | positioned away from RF antenna. It is a figure which shows typically another example of the electromagnetic effect | action when a perfect endless type | mold correction coil is arrange | positioned near RF antenna. It is a figure which shows the change of the current density distribution in the process space near a dielectric material window when the distance space | interval of a perfect endless type | mold correction coil and RF antenna is changed. It is a figure which shows the example of 1 structure of the correction | amendment coil and switching mechanism in 1st Embodiment. It is a figure which shows the specific structural example of the said switching mechanism. It is a figure which shows the PWM control by the said switching mechanism. It is a figure which shows the process of a multilayer resist method in steps. It is a figure which shows the method of carrying out the variable control of the electricity supply duty ratio of a correction coil in the multistep etching process by a multilayer resist method. It is a longitudinal cross-sectional view which shows the structure of the inductively coupled plasma etching apparatus in 2nd Embodiment. It is a figure which shows the example of 1 structure of the correction | amendment coil and resistance variable mechanism in 2nd Embodiment. It is a figure which shows the specific structural example of the said resistance variable mechanism. It is a figure which shows one resistance position in the said resistance variable mechanism. It is a figure which shows another resistance position in the said resistance variable mechanism. It is a figure which shows another resistance position in the said resistance variable mechanism. It is a figure which shows the example of 1 structure of the correction | amendment coil and switching mechanism in one modification of 1st Embodiment. It is a figure which shows the example of 1 structure of the correction | amendment coil and resistance variable mechanism in one modification of 2nd Embodiment. It is a figure which shows an example of an effect | action in the structural example of FIG. 15 or FIG. It is a figure which shows an example of an effect | action in the structural example of FIG. 15 or FIG. It is a figure which shows an example of an effect | action in the structural example of FIG. 15 or FIG. It is a figure which shows one structural example of the correction | amendment coil and opening / closing mechanism in 3rd Embodiment. It is a figure which shows the example of 1 structure of the correction | amendment coil and opening-closing mechanism in one modification. It is a figure which shows the method of controlling the opening / closing state of the switch provided in a single type | mold correction coil in the multistep etching process by a multilayer resist method. It is a figure which shows the method of controlling the open / close state of two switches provided in a twin type | mold correction coil in the multistep etching process by a multilayer resist method. It is a figure which shows the correction | amendment coil and changeover switch network in another embodiment. It is a figure which shows the correction | amendment coil and changeover switch network in another embodiment. It is a figure which shows the Example which cools a correction | amendment coil by an air cooling type. It is a figure which shows one Example which cools a correction coil via a refrigerant | coolant.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
[First Embodiment]

  A first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 shows the configuration of an inductively coupled plasma processing apparatus according to the first embodiment. This inductively coupled plasma processing apparatus is configured as a plasma etching apparatus using a planar coil type RF antenna, and has a cylindrical vacuum chamber (processing vessel) 10 made of metal such as aluminum or stainless steel. . The chamber 10 is grounded for safety.

  First, the configuration of each part not related to plasma generation in this inductively coupled plasma etching apparatus will be described.

  A disc-shaped susceptor 12 on which, for example, a semiconductor wafer W is mounted as a substrate to be processed is horizontally disposed as a substrate holding table that also serves as a high-frequency electrode in the lower center of the chamber 10. The susceptor 12 is made of, for example, aluminum, and is supported by an insulating cylindrical support portion 14 that extends vertically upward from the bottom of the chamber 10.

  An annular exhaust path 18 is formed between the conductive cylindrical support section 16 extending vertically upward from the bottom of the chamber 10 along the outer periphery of the insulating cylindrical support section 14 and the inner wall of the chamber 10. An annular baffle plate 20 is attached to an upper portion or an inlet of 18 and an exhaust port 22 is provided at the bottom. In order to make the gas flow in the chamber 10 uniform on the axis of the semiconductor wafer W on the susceptor 12, it is preferable to provide a plurality of exhaust ports 22 at equal intervals in the circumferential direction.

  An exhaust device 26 is connected to each exhaust port 22 via an exhaust pipe 24. The exhaust device 26 has a vacuum pump such as a turbo molecular pump, and can depressurize the plasma processing space in the chamber 10 to a desired degree of vacuum. Outside the side wall of the chamber 10, a gate valve 28 that opens and closes a loading / unloading port 27 for the semiconductor wafer W is attached.

A high frequency power source 30 for RF bias is electrically connected to the susceptor 12 via a matching unit 32 and a power feed rod 34. The high-frequency power source 30 can output a high-frequency RF _L having a constant frequency (13.56 MHz or less) suitable for controlling the energy of ions drawn into the semiconductor wafer W with variable power. The matching unit 32 accommodates a reactance variable matching circuit for matching between the impedance on the high frequency power source 30 side and the impedance on the load (mainly susceptor, plasma, chamber) side. A blocking capacitor for generating a self-bias is included in the matching circuit.

  On the upper surface of the susceptor 12, an electrostatic chuck 36 for holding the semiconductor wafer W with an electrostatic attraction force is provided, and a focus ring 38 that surrounds the periphery of the semiconductor wafer W in an annular shape is provided radially outward of the electrostatic chuck 36. Provided. The electrostatic chuck 36 is obtained by sandwiching an electrode 36 a made of a conductive film between a pair of insulating films 36 b and 36 c, and a high voltage DC power supply 40 is electrically connected to the electrode 36 a through a switch 42 and a covered wire 43. It is connected. The semiconductor wafer W can be attracted and held on the electrostatic chuck 36 with an electrostatic force by a high-voltage DC voltage applied from the DC power supply 40.

  Inside the susceptor 12, for example, an annular refrigerant chamber or refrigerant flow path 44 extending in the circumferential direction is provided. A refrigerant having a predetermined temperature, such as cooling water cw, is circulated and supplied to the refrigerant chamber 44 through pipings 46 and 48 from a chiller unit (not shown). The temperature during processing of the semiconductor wafer W on the electrostatic chuck 36 can be controlled by the temperature of the coolant. In this connection, a heat transfer gas such as He gas from a heat transfer gas supply unit (not shown) is supplied between the upper surface of the electrostatic chuck 36 and the back surface of the semiconductor wafer W via the gas supply pipe 50. Is done. Further, for loading / unloading of the semiconductor wafer W, lift pins that can vertically move through the susceptor 12 and a lifting mechanism (not shown) and the like are also provided.

  Next, the configuration of each part related to plasma generation in this inductively coupled plasma etching apparatus will be described.

  A circular dielectric window 52 made of, for example, a quartz plate is airtightly attached to the ceiling of the chamber 10 at a relatively large distance from the susceptor 12. On the dielectric window 52, a coiled RF antenna 54 is disposed horizontally, usually coaxially with the chamber 10 or the susceptor 12. The RF antenna 54 preferably has, for example, a spiral coil (FIG. 2A) or a concentric coil (FIG. 2B) having a constant radius within each circumference, and an antenna fixing member (not shown) made of an insulator. Is fixed on the dielectric window 52.

  One end of the RF antenna 54 is electrically connected to an output terminal of a high-frequency power source 56 for plasma generation via a matching unit 58 and a feeder line 60. Although not shown, the other end of the RF antenna 54 is electrically connected to the ground potential via an earth wire.

The high-frequency power source 56 can output a high-frequency RF _H having a constant frequency (13.56 MHz or more) suitable for generating plasma by high-frequency discharge with variable power. The matching unit 58 accommodates a reactance variable matching circuit for matching between the impedance on the high frequency power supply 56 side and the impedance on the load (mainly RF antenna, plasma, correction coil) side.

  A processing gas supply unit for supplying a processing gas to a processing space in the chamber 10 is an annular manifold or buffer unit 62 provided in (or outside) the side wall of the chamber 10 at a position somewhat lower than the dielectric window 52. A plurality of side wall gas discharge holes 64 facing the plasma generation space from the buffer unit 62 at equal intervals in the circumferential direction, and a gas supply pipe 68 extending from the processing gas supply source 66 to the buffer unit 62. The processing gas supply source 66 includes a flow rate controller and an on-off valve (not shown).

  This inductively coupled plasma etching apparatus is an antenna in an atmospheric pressure space provided on the top plate of the chamber 10 in order to variably control the density distribution of the inductively coupled plasma generated in the processing space in the chamber 10 in the radial direction. A correction coil 70 that can be coupled indoors to the RF antenna 54 by electromagnetic induction, and a switching mechanism 110 for variably controlling the duty ratio of the energization current that flows through the correction coil 70 are provided. The configuration and operation of the correction coil 70 and the switching mechanism 110 will be described in detail later.

  The main control unit 74 includes, for example, a microcomputer. Each unit in the plasma etching apparatus, for example, the exhaust device 26, the high frequency power sources 30, 56, the matching units 32, 58, the electrostatic chuck switch 42, the processing gas supply source 66, It controls individual operations of the switching mechanism 110, a chiller unit (not shown), a heat transfer gas supply unit (not shown), and the operation (sequence) of the entire apparatus.

In order to perform etching in this inductively coupled plasma etching apparatus, the gate valve 28 is first opened, and the semiconductor wafer W to be processed is loaded into the chamber 10 and placed on the electrostatic chuck 36. After the gate valve 28 is closed, the etching gas (generally a mixed gas) is supplied from the processing gas supply source 66 through the gas supply pipe 68, the buffer unit 62, and the side wall gas discharge holes 64 at a predetermined flow rate and flow rate ratio. The pressure in the chamber 10 is set to a set value by the exhaust device 26. Further, the high frequency power source 56 is turned on to output a high frequency RF _H for plasma generation at a predetermined RF power, and a current of the high frequency RF _H is supplied to the RF antenna 54 via the matching unit 58 and the feeder line 60. On the other hand, the high frequency power supply 30 is turned on to output a high frequency RF _L for controlling the ion attraction at a predetermined RF power, and this high frequency RF _L is applied to the susceptor 12 via the matching unit 32 and the power feed rod 34. Further, the heat transfer gas (He gas) is supplied from the heat transfer gas supply unit to the contact interface between the electrostatic chuck 36 and the semiconductor wafer W, and the electrostatic chucking force of the electrostatic chuck 36 is turned on by turning on the switch 42. The heat transfer gas is confined in the contact interface.

The etching gas discharged from the side wall gas discharge holes 64 is uniformly diffused into the processing space below the dielectric window 52. By the current of the high frequency RF _H flowing RF antenna 54, RF magnetic field that the magnetic force lines to pass through the plasma generation space in the chamber through the dielectric window 52 is generated around the RF antenna 54, the time of the RF magnetic field Due to such a change, an RF induction electric field is generated in the azimuth direction of the processing space. Then, the electrons accelerated in the azimuth direction by the induced electric field cause ionization collisions with the molecules and atoms of the etching gas, and a donut-shaped plasma is generated. The radicals and ions of the doughnut-shaped plasma diffuse in all directions in a wide processing space, the radicals flow isotropically, and the ions are pulled by a DC bias, so that the top surface (surface to be processed) of the semiconductor wafer W To be supplied. In this way, the active species of plasma cause a chemical reaction and a physical reaction on the surface to be processed of the wafer W, and the film to be processed is etched into a desired pattern.

This inductively coupled plasma etching apparatus generates inductively coupled plasma in a donut shape under the dielectric window 52 close to the RF antenna 54 as described above, and disperses the donut shaped plasma in a wide processing space. Thus, the plasma density is averaged in the vicinity of the susceptor 12 (that is, on the semiconductor wafer W). Here, the density of the donut-shaped plasma depends on the strength of the induction electric field, and in turn depends on the magnitude of the power of the high-frequency RF _H supplied to the RF antenna 54 (more precisely, the current flowing through the RF antenna 54). That is, as the power of the high frequency RF _H is increased, the density of the donut-shaped plasma is increased, and the density of the plasma in the vicinity of the susceptor 12 is generally increased through the diffusion of the plasma. On the other hand, the form in which the donut-shaped plasma diffuses in all directions (especially in the radial direction) mainly depends on the pressure in the chamber 10, and the lower the pressure, the more plasma gathers at the center of the chamber 10, and the vicinity of the susceptor 12. The plasma density distribution tends to swell in the center. Further, the plasma density distribution in the donut-shaped plasma may change depending on the power of the high-frequency RF _H supplied to the RF antenna 54, the flow rate of the processing gas introduced into the chamber 10, or the like.

  Here, the “doughnut-shaped plasma” is not limited to a strictly ring-shaped plasma in which plasma does not stand on the radially inner side (center portion) of the chamber 10 but only on the radially outer side. This means that the volume or density of plasma on the outer side in the radial direction is larger than the inner side in the radial direction. Further, depending on conditions such as the type of gas used for the processing gas and the pressure value in the chamber 10, the “doughnut-shaped plasma” may not occur.

  In this plasma etching apparatus, in order to uniformize the plasma density distribution in the vicinity of the susceptor 12 in the radial direction, the RF magnetic field generated by the RF antenna 54 is corrected electromagnetically by the correction ring 70, and the process conditions ( The energization duty ratio of the correction coil 70 is varied by the switching mechanism 110 in accordance with the pressure in the chamber 10).

  Hereinafter, the configuration and operation of the correction ring 70 and the switching mechanism 110, which are the main features of the inductively coupled plasma etching apparatus, will be described.

  More specifically, as shown in FIG. 6, the correction coil 70 is composed of an annular single winding coil (or multiple winding coil) having both ends opened with an appropriate gap g interposed therebetween, and the coil conductor in the radial direction is the RF antenna 54. Is arranged coaxially with respect to the RF antenna 54 so as to be located between the inner periphery and the outer periphery (preferably near the center) of the coil, and an insulating coil holding member (see FIG. (Not shown). The material of the correction coil 70 is preferably, for example, a copper metal having high conductivity.

  In the present invention, “coaxial” means a positional relationship in which the central axes of a plurality of coils or antennas overlap each other, and the respective coil surfaces or antenna surfaces are offset from each other in the axial direction or the vertical direction. This includes not only the case but also the case of matching on the same plane (concentric positional relationship).

  Here, a configuration in which the correction coil 70 has no gap g is referred to as a complete endless correction coil 70 ′, and an operation when the height position of the complete endless correction coil 70 ′ is changed will be described.

First, as shown in FIG. 3A, when the height position of the complete endless correction coil 70 ′ is set near the upper limit value, an RF magnetic field generated around the antenna conductor by the high-frequency RF _H current flowing through the RF antenna 54. H forms a loop-shaped magnetic field line that passes through the processing space under the dielectric window 52 in the radial direction without being affected by the complete endless correction coil 70 ′.

The radial (horizontal) component Br of the magnetic flux density in the processing space is always zero at the center (O) and the peripheral portion of the chamber 10 irrespective of the magnitude of the high-frequency RF _H current, and in the RF antenna 54 in the radial direction. It becomes a maximum at a position that overlaps the middle of the periphery and the periphery (hereinafter referred to as “antenna middle part”), and the maximum value increases as the current of the high frequency RF _H increases. The intensity distribution of the induced electric field in the azimuth direction generated by the RF magnetic field H also has a profile similar to the magnetic flux density Br in the radial direction. Thus, a donut-shaped plasma is formed near the dielectric window 52 and coaxially with the RF antenna 54.

  This donut-shaped plasma diffuses in all directions (particularly in the radial direction) in the processing space. As described above, the diffusion form depends on the pressure in the chamber 10, but as an example, as shown in FIG. 3A, the electron density (plasma density) in the radial direction in the vicinity of the susceptor 12 relatively corresponds to the antenna middle part. In some cases, the profile is high (while remaining at the maximum) and falls in the center and the periphery.

In such a case, as shown in FIG. 3B, when the height position of the complete endless correction coil 70 'is lowered to, for example, the vicinity of the lower limit value, the antenna is generated by the current of the high-frequency RF _H flowing through the RF antenna 54 as shown. The RF magnetic field H generated around the conductor is affected by the reaction of electromagnetic induction by the completely endless correction coil 70 '. The reaction of this electromagnetic induction is an action to counter the change of the magnetic field lines (magnetic flux) penetrating through the loop of the complete endless correction coil 70 ', and an induced electromotive force is generated in the loop of the complete endless correction coil 70'. Current flows.

  Thus, the magnetic flux in the processing space near the dielectric window 52 at a position almost directly below the coil conductor (especially the antenna middle portion) of the complete endless correction coil 70 ′ due to the reaction of electromagnetic induction from the complete endless correction coil 70 ′. The radial (horizontal) component Br of the density is locally weakened, so that the strength of the induced electric field in the azimuth direction is also locally weakened at a position corresponding to the antenna middle portion, like the magnetic flux density Br. As a result, the electron density (plasma density) is more uniform in the radial direction in the vicinity of the susceptor 12.

  The plasma diffusion form as shown in FIG. 3A is an example. For example, when the pressure is low, the plasma gathers too much in the center of the chamber 10 and the electron density (plasma density) in the vicinity of the susceptor 12 as shown in FIG. 4A. May show a mountain-shaped profile that is relatively maximum at the center.

  Even in such a case, as shown in FIG. 4B, when the complete endless correction coil 70 ′ is lowered to, for example, the vicinity of the lower limit value, the position of the middle portion overlapping the coil conductor of the complete endless correction coil 70 ′ as shown in FIG. Thus, the radial (horizontal) component Br of the magnetic flux density in the processing space near the dielectric window 52 is locally weakened, whereby the concentration of plasma at the center of the chamber is weakened, and the plasma density near the susceptor 12 is radial. It is evenly uniform.

  The inventor verified the operation of the complete endless correction coil 70 ′ as described above by electromagnetic field simulation. That is, the relative height position (distance interval) of the complete endless correction coil 70 ′ with respect to the RF antenna 54 is used as a parameter, and the parameter value is selected from four types of 5 mm, 10 m, 20 mm, and infinity (no correction coil). When the current density distribution (corresponding to the plasma density distribution) in the radial direction inside the donut-shaped plasma (position of 5 mm from the upper surface) was obtained, the verification result shown in FIG. 5 was obtained.

In this electromagnetic field simulation, the outer diameter (radius) of the RF antenna 54 was set to 250 mm, and the inner and outer radii of the complete endless correction coil 70 ′ were set to 100 mm and 130 mm, respectively. The donut-shaped plasma generated by inductive coupling in the processing space in the chamber below the RF antenna 54 is simulated by a disk-shaped resistor. The resistor has a diameter of 500 mm, a resistivity of 100 Ωcm, and a skin thickness of 10 mm. Set to. The frequency of the high frequency RF _H for plasma generation was 13.56 MHz.

  From FIG. 5, when the complete endless correction coil 70 ′ is disposed at a height position where it is coupled to the RF antenna 54 by electromagnetic induction, the plasma density in the donut-shaped plasma overlaps with the coil conductor of the correction coil 70 (in the illustrated example, It can be seen that the local reduction in the vicinity of the position overlapping the antenna middle part) and the degree of local reduction increases substantially linearly as the RF antenna 54 is brought closer to the complete endless correction coil 70 ′.

  In the inductively coupled plasma etching apparatus (FIG. 1) of this embodiment, as shown in FIG. 6, instead of using the complete endless correction coil 70 ′ as described above, both ends are opened with an appropriate gap g interposed therebetween. A correction coil 70 composed of a single coil (or multiple coil) is used, and a switching element 112 is connected between both open ends of the correction coil 70.

  The switching mechanism 110 includes a switching control circuit 114 that performs on / off control or switching control of the switching element 112 at a constant frequency (for example, 1 to 100 kHz) by pulse width modulation (PWM).

  FIG. 7 shows a specific configuration example of the switching mechanism 110. In this configuration example, a pair of transistors (for example, IGBT or MOS transistors) 112A and 112B are connected in parallel in reverse directions as the switching element 112, and reverse bias protection diodes 116A and 116B are connected in series with the respective transistors 112A and 112B. 116B is connected.

Both transistors 112A and 112B are simultaneously turned on / off by the PWM control signal SW from the switching control circuit 114. During the ON period, the positive induced current i ₊ flowing in the positive direction through the correction coil 70 in the first half cycle of the high frequency flows through the first transistor 112A and the first diode 116A, and the correction coil in the second half cycle of the high frequency. The negative induced current i ₋ that flows in the reverse direction through the transistor 70 flows through the second transistor 112B and the second diode 116B.

Although not shown, the switching control circuit 114 has, for example, a triangular wave generating circuit that generates a triangular wave signal having a constant frequency, and a variable voltage level corresponding to a desired duty ratio (ratio of the ON period of one cycle pulse). A variable voltage signal generating circuit for generating a voltage signal; a comparator for comparing the voltage levels of the triangular wave signal and the variable voltage signal to generate a binary PWM control signal SW according to the magnitude relationship; and both transistors And a drive circuit for driving 112A and 112B with a PWM control signal SW. Here, the desired duty ratio is given from the main control unit 74 to the switching control circuit 114 through a predetermined control signal _SD .

  According to this embodiment, the energization duty ratio of the correction coil 70 is controlled by PWM control during the plasma process by the switching mechanism 110 configured as described above, and the energization duty ratio is controlled as shown in FIG. Variable control can be arbitrarily performed within the range of 0% to 100%.

What is important here is that the duty ratio of the energization that causes the induction current i to flow through the correction coil 70 by PWM control as described above can be arbitrarily varied in the range of 0% to 100%. the height position of the mold the correction coil 70 'is that it is an optionally functionally equivalent to varying between a lower limit position close to the home position H _P and RF antenna 54 near the upper limit position. From another point of view, it is possible to realize the characteristics of FIG. 5 as a device by fixing the correction coil 70 at the height position near the RF antenna 54 by the switching mechanism 110. As a result, the degree of freedom and accuracy in controlling the plasma density distribution can be easily achieved.

Therefore, every time when all or a part of the process conditions changes in the process recipe, the energization duty ratio of the correction coil 70 is variably controlled through the switching mechanism 110, whereby the antenna conductor is controlled by the high-frequency RF _H current flowing through the RF antenna 54. Of the correction coil 70 with respect to the RF magnetic field H generated around, that is, the degree (strength) of the effect of locally reducing the plasma density in the donut-shaped plasma around the position where it overlaps the coil conductor of the correction coil 70 is arbitrary and fine Can be adjusted to.

  The inductively coupled plasma etching apparatus in this embodiment can be suitably applied to, for example, an application that continuously etches a multilayer film on a substrate surface in a plurality of steps. Examples of the present invention relating to the multilayer resist method as shown in FIG. 9 will be described below.

  In FIG. 9, a SiN layer 102 is formed on the main surface of a semiconductor wafer W to be processed as a lowermost layer (final mask) on an original film to be processed (for example, a Si film for a gate) 100. An organic film (for example, carbon) 104 is formed as an intermediate layer, and an uppermost photoresist 108 is formed thereon via a Si-containing antireflection film (BARC) 106. For the formation of the SiN layer 102, the organic film 104 and the antireflection film 106, a coating film by CVD (chemical vacuum deposition) or spin-on is used, and for the patterning of the photoresist 108, photolithography is used.

First, as a first step etching process, the Si-containing antireflection film 106 is etched using the patterned photoresist 108 as a mask as shown in FIG. In this case, a mixed gas of CF ₄ / O ₂ is used as the etching gas, and the pressure in the chamber 10 is relatively low, for example, set to 10 mTorr.

Next, as a second step etching process, as shown in FIG. 9B, the organic film 104 is etched using the photoresist 108 and the antireflection film 106 as a mask. In this case, a single gas of O ₂ is used as the etching gas, and the pressure in the chamber 10 is further lowered, for example, set to 5 mTorr.

Finally, as a third step etching process, as shown in FIGS. 9C and 9D, the SiN film 102 is etched using the patterned antireflection film 106 and organic film 104 as a mask. In this case, a mixed gas of CHF ₃ / CF ₄ / Ar / O ₂ is used as the etching gas, and the pressure in the chamber 10 is relatively high, for example, set to 50 mTorr.

  In the multi-step etching process as described above, all or a part of the process conditions (particularly the pressure in the chamber 10) is switched for each step, thereby changing the form of diffusion of the donut-shaped plasma in the processing space. . Here, when the correction coil 70 is not functioned (energized) at all, in the first and second step processes (pressure 10 mTorr or less), the electron density (plasma density) near the susceptor 12 is relatively centered as shown in FIG. 4A. It is assumed that a steep mountain-shaped profile that rises remarkably in the region appears, and a gentle mountain-shaped profile that slightly rises in the center portion appears in the third step process (pressure 50 mTorr).

  According to this embodiment, for example, in a process recipe, the duty ratio of the correction coil 70 is added to or linked to normal process conditions (high-frequency power, pressure, gas type, gas flow rate, etc.). Set the ratio as one of recipe information or process parameters. When the multi-step etching process as described above is performed, the main control unit 74 reads data representing the energization duty ratio from the memory, and the energization duty of the correction coil 70 is changed through the switching mechanism 110 for each step. Adjust the ratio to the set value.

For example, when a multi-step etching process using a multilayer resist method as shown in FIG. 9 is performed, as shown in FIG. 10, the second step ( ₁ ) (10 mTorr) has a relatively large duty ratio D _1. At 5 mTorr), the energization duty ratio of the correction coil 70 is switched at every step to a larger duty ratio D ₂ , and at the third step (50 mTorr), to a relatively small duty ratio D ₃ .

Also, from the viewpoint of plasma ignitability, immediately after the start of the process of each step, the energization of the correction coil 70 is forcibly held off to stably ignite the plasma. A technique that matches the ratio is also effective.

[Second Embodiment]

  Next, a second embodiment of the present invention will be described with reference to FIGS.

  FIG. 11 shows the configuration of an inductively coupled plasma etching apparatus according to the second embodiment. In the figure, parts having the same configuration or function as those of the apparatus of the first embodiment (FIG. 1) described above are denoted by the same reference numerals.

  The feature of the second embodiment is that it includes a variable resistance mechanism 120 instead of the switching mechanism 110 in contrast to the first embodiment described above.

  More specifically, the correction coil 70 is formed of an annular single winding coil or a multiple winding coil having both ends opened with an appropriate gap g interposed therebetween, and the coil conductor is between the inner periphery and the outer periphery of the RF antenna 54 in the radial direction. It is arranged coaxially with respect to the RF antenna 54 so as to be located (preferably near the center), and is held horizontally by an insulating coil holding member (not shown) at a height position close to the RF antenna 54. .

  As shown in FIG. 12, the variable resistance mechanism 120 includes a variable resistance 122 connected to both open ends of the correction coil 70, and a resistance control unit 124 that controls the resistance value of the variable resistance 122 to a desired value. doing.

  FIG. 13 shows a specific configuration example of the variable resistance mechanism 120. The variable resistor 122 in this configuration example includes a high-resistance metal-based or carbon-based resistor 128 inserted through an insulator 126 so as to close the gap g between both open ends of the correction coil 70, and a correction. It has a bridging short-circuit conductor 130 that short-circuits between two points on the coil 70 that are separated by a certain distance. The material of the bridging short-circuit conductor 130 is preferably a copper-based metal having high conductivity.

  The resistance control unit 124 supports the bridge type short-circuit conductor 130 and slides it on the correction coil 70, and a resistance for adjusting the position of the bridge type short-circuit conductor 130 to a desired resistance position through the slide mechanism 132. And a position control unit 134.

  More specifically, the slide mechanism 132 includes a ball screw mechanism, and includes a stepping motor 138 for rotating the feed screw 136 that extends horizontally at a fixed position, and a nut portion (not shown) that is screwed with the feed screw 136. A slider main body 140 that horizontally moves in the axial direction by the rotation of the feed screw 136, a compression coil spring 142 that couples the slider main body 140 and the bridging short-circuit conductor 130, and a pair of slidably fitted in the vertical direction. It consists of cylindrical bodies 144 and 146. Here, the outer cylindrical body 144 is fixed to the slider body 140, and the inner cylindrical body 146 is fixed to the bridging short-circuit conductor 130. The compression coil spring 142 presses the bridging short-circuit conductor 130 against the correction coil 70 by elastic force.

The resistance position control unit 134 controls the position of the bridging short-circuit conductor 130 through the rotation direction and the rotation amount of the stepping motor 138. The target position of the cross-linked shorting conductors 130 are given to the resistance position controller 134 via a predetermined control signal S _R from the main control unit 74 (FIG. 11).

  Here, the action of the variable resistance mechanism 120 will be described with reference to FIGS. 13 and 14A to 14C.

  First, when the bridging short-circuit conductor 130 is set at the position shown in FIG. 13, both ends of the coil conductor of the correction coil 70 are bypassed and short-circuited by the bridging short-circuit conductor 130 without passing through the resistor 128. As a result, the resistance value of the variable resistor 122 becomes the lowest value (substantially zero), and thereby the coil resistance value of the entire correction coil 70 becomes the lowest value.

  Assume that the bridging short-circuit conductor 130 is slid to the right in the figure and positioned at the position shown in FIG. 14A from the state shown in FIG. At this position, the contact portion 130R at one end (right end) of the bridging short-circuit conductor 130 remains connected to one end (right end) portion of the coil conductor, but the contact portion 130L at the other end (left end) is connected to the other end of the coil conductor. It is in the section of the resistor 128 beyond (the left end). As a result, the resistance value of the variable resistor 122 becomes a significant value that is not zero, and the coil resistance value of the entire correction coil 70 becomes higher than that in FIG.

  When the bridging short-circuit conductor 130 is further slid to the right in the figure from the state of FIG. 14A, the section length of the resistor 128 occupying the current path of the correction coil 70 increases, and the resistance value of the variable resistor 122 becomes that value. The coil resistance value of the correction coil 70 as a whole becomes even higher than that shown in FIG. 14A.

  14B, when the contact portion 130L at the left end of the bridging short-circuit conductor 130 is moved to the other end of the resistor 128 on the insulator 126 side, the resistor 128 occupying the current path of the correction coil 70. The section length of becomes the maximum. As a result, the resistance value of the variable resistor 122 is maximized, and the coil resistance value of the entire correction coil 70 is maximized.

  14B, the bridging short-circuit conductor 130 is further slid to the right in the figure, and the contact portion 130L at the left end of the bridging short-circuit conductor 130 passes over the insulator 126 as shown in FIG. 14C. When the coil coil is moved to the right coil conductor, the correction coil 70 is electrically disconnected by the insulator 126 and is substantially open at both ends. From another viewpoint, the resistance value of the variable resistor 122 becomes infinite.

  Thus, in this embodiment, the resistance value of the variable resistor 122 is variably controlled by the variable resistance mechanism 120, and as described above, the coil resistance of the entire correction coil 70 is the minimum resistance equivalent to a closed coil at both ends. It is possible to continuously vary from the value (FIG. 13) to the maximum resistance value (FIGS. 14A and 14B) including the entire section of the resistor 128, and further, coil cutting equivalent to the absence of the correction coil 70 The state (FIG. 14C) can also be selected.

As a result, when a high frequency RF _H current is passed through the RF antenna 54, the current value (amplitude value or peak value) of the current flowing through the correction coil 70 by electromagnetic induction is arbitrarily variable within a range of 0% to 100%. Can be controlled. Here, a current value of 100% corresponds to a current value when flowing at a position in a coil short-circuit state (FIG. 13), and a current value of 0% corresponds to a current value when flowing at a position in a coil-cut state (FIG. 14C). .

What is important here is that the current value of the current flowing through the correction coil 70 can be arbitrarily varied within the range of 0% to 100% by the resistance variable control of the correction coil 70 as described above. the height position of the mold the correction coil 70 'is that it is an optionally functionally equivalent to varying between a lower limit position close to the home position H _P and RF antenna 54 near the upper limit position. From another point of view, it is possible to realize the characteristic of FIG. 5 as a device by fixing the correction coil 70 at a height position near the RF antenna 54 by the resistance variable mechanism 120. The degree of freedom and accuracy of plasma density distribution control can be achieved more simply as in the embodiment.

Therefore, each time the value of a predetermined process parameter changes in the process recipe, the amplitude value of the current flowing through the correction coil 70 through the resistance variable mechanism 120 is variably controlled, so that the antenna is controlled by the high-frequency RF _H current flowing through the RF antenna 54. The action of the correction coil 70 on the RF magnetic field H generated around the conductor, that is, the degree (strength) of the effect of locally reducing the plasma density in the donut-shaped plasma around the position where the correction coil 70 overlaps the coil conductor Can be finely adjusted. As a result, the plasma density in the vicinity of the susceptor 12 can be kept uniform in the radial direction throughout all the steps, and the uniformity of the etching process in the multilayer resist method can be improved.

For example, when performing a multi-step etching process by a multilayer resist method as shown in FIG. 9, although not shown, the first step (10 mTorr) has a relatively low resistance value (resistance position) R ₁ and the second step. At 5 mTorr, the resistance value (resistance position) R ₂ is set to a lower resistance value (resistance position) R _{2. At} the third step (50 mTorr), the resistance value (resistance position) R ₃ is set to a relatively high resistance value (resistance position) R _3. Switch.

Further, from the viewpoint of plasma ignitability, immediately after the start of the process of each step, the correction coil 70 is held in an electrically disconnected state (FIG. 14C) to ignite the plasma stably and after the ignition of the plasma, the variable resistor 122 It is also effective to adjust the value to a preset resistance value (resistance position).

[Modification]

  FIG. 15 shows a modification of the correction coil 70 and the switching mechanism 110 in the first embodiment. In this embodiment, a plurality of (for example, two) correction coils 70A and 70B having different coil diameters are arranged concentrically (or coaxially), and the switching elements 112A and 112B are placed in the loop of the correction coils 70A and 70B. Are provided respectively. The switching elements 112A and 112B are independently controlled to be turned on / off by PWM control with an arbitrary energization duty ratio by the individual switching control circuits 114A and 114B.

  FIG. 16 shows a modification of the correction coil 70 and the variable resistance mechanism 120 in the second embodiment. In this embodiment, a plurality of (for example, two) correction coils 70A and 70B having different coil diameters are arranged concentrically (or coaxially), and variable resistors 122A and 122B are provided in the loops of the correction coils 70A and 70B. Are provided respectively. The resistance values of the variable resistors 122A and 122B are independently and arbitrarily variably controlled by the individual resistance control units 124A and 124B.

  In the switching mechanism 110 of FIG. 15 and the variable resistance mechanism 120 of FIG. 16, the combinations of the values of the induced current (energization duty ratio or peak value) flowing through the two correction coils 70A and 70B are arbitrary and various. The degree of freedom in controlling the plasma density distribution can be further expanded.

As shown in FIG. 17A, it is also possible to operate (energize) only the correction coil 70A while holding the correction coil 70B in a non-actuated (non-energized) state. Alternatively, as shown in FIG. 17B, it is also possible to operate (energize) only the correction coil 70B while holding the correction coil 70A in a non-actuated (non-energized) state. Further, as shown in FIG. 17C, both correction coils 70A and 70B can be operated (energized) simultaneously.

[Third Embodiment]

  As another embodiment, in the first embodiment, the switching mechanism 110 may be replaced with an opening / closing mechanism 150 as shown in FIG. The opening / closing mechanism 150 performs switching control of a switch 152 connected to both open ends of the correction coil 70 via a conductor and an open / close (on / off) state of the switch 152 based on an instruction from the main control unit 74. And an open / close control circuit 154.

In the opening / closing mechanism 150, when the switch 152 is switched to the open (off) state, the induced current does not flow through the correction coil 70, which is equivalent to the case where the correction coil 70 is not provided. When the switch 152 is switched to the closed (on) state, the correction coil 70 is equivalent to a coil closed at both ends, and when a high-frequency RF _H current flows through the RF antenna 54, an induced current flows through the correction coil 70. .

  As shown in FIG. 19, such an opening / closing mechanism 150 can be applied to a configuration in which a plurality of correction coils 70A and 70B are arranged concentrically. That is, a plurality (for example, two) of correction coils 70A and 70B having different coil diameters are arranged concentrically, and switches 152A and 152B are inserted and connected to the correction coils 70A and 70B, respectively. The switches 152A and 152B can be independently controlled to be opened and closed by the individual switching control circuits 154A and 154B. Also in such a switch system, the degree of freedom of control is limited to some extent, but variable control of the current density (doughnut-shaped plasma density) distribution as shown in FIGS. 17A to 17C can be performed.

  Further, when the opening / closing mechanism 150 as described above is provided, the opening / closing state of the switch 150 (152A, 152B) is changed in accordance with the change, change, or switching of the process conditions in the plasma processing for one substrate to be processed. It is possible to suitably take a method of controlling the above.

  For example, in the case of using a single correction coil 70 (switch 152) as shown in FIG. 18 in the multi-step etching process (FIG. 9) using the multilayer resist method as described above, as shown in FIG. In the first step, the switch 152 is switched to the open (off) state, in the second step, the switch 152 is switched to the closed (on) state, and in the third step, the switch 152 is switched to the open (off) state.

  Further, when the twin type correction coils 70A and 70B (switches 152A and 152B) as shown in FIG. 19 are used, the switches 152A and 152B are both opened (off) in the first step as shown in FIG. In the second step, both the switches 152A and 152B are switched to the closed (on) state, and in the third step, the switch 152A is switched to the open (off) state and the switch 152B is switched to the closed (on) state.

  In addition, as shown in FIG. 22, the same switches 152A, 152B, 152C and open / close as described above can be used in the configuration in which a plurality of (for example, three) correction coils 70A, 70B, 70c are arranged in the longitudinal direction and arranged coaxially. Control circuits 154A, 154B, and 154C (not shown) can be applied.

  As another example of the correction coil 70, as shown in FIG. 23, a plurality of (for example, three) coil conductors 70 (1), 70 (2), and 70 (3) each function as an individual correction coil. A configuration in which a mode and a connection mode that functions as one correction coil electrically connected in series can be selectively switched is also possible.

  In FIG. 23, each of the coil conductors 70 (1), 70 (2), 70 (3) is composed of an annular single winding coil (or multiple winding coil) having both ends opened with an appropriate gap therebetween. Can be electrically connected in multiple types of modes via three changeover switches 160, 162, 164 and one open / close switch 166.

  The first changeover switch 160 includes a first fixed contact 160a connected to one end of the innermost coil conductor 70 (1), a movable contact 160b connected to the other end of the coil conductor 70 (1), A second fixed contact 160c connected to one end of the adjacent intermediate coil conductor 70 (2).

  The second changeover switch 162 includes a first fixed contact 162a connected to one end of the intermediate coil conductor 70 (2), a movable contact 162b connected to the other end of the coil conductor 70 (2), and an outer side adjacent. And a second fixed contact 162c connected to one end of the coil conductor 70 (3).

  The third changeover switch 164 includes a first fixed contact 164a connected to one end of the outer coil conductor 70 (3), a movable contact 164b connected to the other end of the coil conductor 70 (3), and an open / close switch. A movable contact 166d of 166 has a second fixed contact 164c.

  The fixed contact 166e of the open / close switch 166 is connected to one end of the inner coil conductor 70 (1).

  In this configuration, when the single mode is selected, the movable contact 160b of the first changeover switch 160 is switched to the first fixed contact 160a, and the movable contact 162b of the second changeover switch 162 is changed to the first fixed contact 162a. The movable contact 164b of the third switch 164 is switched to the first fixed contact 164a, and the open / close switch 166 is switched to the open state.

  When selecting the connection mode, the movable contact 160b of the first changeover switch 160 is switched to the second fixed contact 160c, the movable contact 162b of the second changeover switch 162 is switched to the second fixed contact 162c, The movable contact 164b of the third changeover switch 164 is switched to the second fixed contact 164c, and the open / close switch 166 is switched to the closed state.

  As a modification of this embodiment, for example, of the three coil conductors 70 (1), 70 (2), and 70 (3), any two coil conductors are selected for the connection mode, and the remaining one is used alone. A switch network configuration that allows selection of modes is also possible.

  In addition, a large induction current (sometimes a current greater than the current flowing through the RF antenna) may flow through the correction coil of the present invention, and it is important to pay attention to the heat generated by the correction coil.

  From this point of view, as shown in FIG. 24A, a coil cooling unit that cools by an air cooling method by installing an air cooling fan in the vicinity of the correction coil 70 can be provided. Alternatively, as shown in FIG. 24B, the correction coil 70 may be formed of a hollow copper tube, and a coil cooling unit that supplies refrigerant therein to prevent the correction coil 70 from overheating can be provided.

  The configuration of the inductively coupled plasma etching apparatus in the above-described embodiment is an example, and various modifications can be made to the configuration of each part not directly related to plasma generation as well as each part of the plasma generation mechanism.

  For example, in the above-described embodiment, the correction coil 70 is fixedly arranged at one place, but it is also possible to adopt a configuration in which the position of the correction coil 70 is varied, in particular, a configuration in which the height position is arbitrarily varied.

  In addition to the switching element 112, resistor 122, or switch 152 (152A, 152B, 152C) described above, for example, a capacitor (not shown) may be provided in the current path or loop of the correction coil 70. .

  In addition, as a basic form of the RF antenna 54 and the correction antenna 70, a type other than the planar shape, for example, a dome shape can be used. Furthermore, the type installed in places other than the ceiling of the chamber 10 is also possible, for example, the helical type installed outside the side wall of the chamber 10 is also possible.

  Also, a chamber structure for a rectangular substrate, a rectangular RF antenna structure, and a rectangular correction coil structure are possible.

Further, the processing gas supply unit may be configured to introduce the processing gas into the chamber 10 from the ceiling, and may be configured such that the high frequency RF _L for DC bias control is not applied to the susceptor 12. On the other hand, a plasma using a plurality of RF antennas or antenna segments and individually supplying high-frequency power for generating plasma to the plurality of RF antennas (or antenna segments) from a plurality of high-frequency power sources or high-frequency power supply systems. The present invention can also be applied to an apparatus.

  Furthermore, the inductively coupled plasma processing apparatus or plasma processing method according to the present invention is not limited to the technical field of plasma etching, and can be applied to other plasma processes such as plasma CVD, plasma oxidation, plasma nitridation, and sputtering. . Further, the substrate to be processed in the present invention is not limited to a semiconductor wafer, and various substrates for flat panel displays, photomasks, CD substrates, printed substrates, and the like are also possible.

DESCRIPTION OF SYMBOLS 10 Chamber 12 Susceptor 56 High frequency power supply 66 Processing gas supply source 70 Correction coil 110 Switching mechanism 112 Switching element 120 Resistance variable mechanism 122 Variable resistance 124 Resistance variable mechanism 150 Opening and closing mechanism 152,152A, 152B, 152C Switch

Claims (6)

A processing vessel having a dielectric window ;
A coiled RF antenna disposed outside the dielectric window;
A substrate holding unit for holding a substrate to be processed in the processing container;
A processing gas supply unit for supplying a desired processing gas into the processing container in order to perform a desired plasma processing on the substrate;
A high-frequency power feeding unit that supplies high-frequency power having a frequency suitable for high-frequency discharge of the processing gas to the RF antenna in order to generate plasma of the processing gas by inductive coupling in the processing container;
In order to control the plasma density distribution on the substrate in the processing container, a correction coil disposed outside the processing container at a position that can be coupled to the RF antenna by electromagnetic induction;
A switching element provided in a loop of the correction coil;
A plasma processing apparatus comprising: a switching control unit configured to control on / off of the switching element by pulse width modulation at a desired duty ratio. A processing vessel having a dielectric window on the ceiling;
A coiled RF antenna disposed on the dielectric window;
A substrate holding unit for holding a substrate to be processed in the processing container;
A processing gas supply unit for supplying a desired processing gas into the processing container in order to perform a desired plasma processing on the substrate;
A high-frequency power feeding unit that supplies high-frequency power having a frequency suitable for high-frequency discharge of the processing gas to the RF antenna in order to generate plasma of the processing gas by inductive coupling in the processing container;
In order to control the plasma density distribution on the substrate in the processing vessel, it is arranged coaxially with the RF antenna, is located between the inner and outer circumferences of the RF antenna in the radial direction, and both ends are gaps. A correction coil disposed on the RF antenna at a height position that can be coupled to the RF antenna by electromagnetic induction,
A variable resistor provided in the gap of the correction coil;
And a resistance control unit that controls a resistance value of the variable resistor to a desired value.   The variable resistor includes a resistor provided in series with the coil conductor in a gap of the correction coil, and a bridge-type movable across the coil conductor and the resistor in the circumferential direction of the correction coil. The plasma processing apparatus of Claim 2 which has a short circuit conductor and can select a desired resistance value with the position of the said short circuit conductor. A processing vessel having a dielectric window ;
An RF antenna disposed outside the dielectric window;
A substrate holding unit for holding a substrate to be processed in the processing container;
A processing gas supply unit for supplying a desired processing gas into the processing container in order to perform a desired plasma processing on the substrate;
A high-frequency power feeding unit that supplies high-frequency power having a frequency suitable for high-frequency discharge of the processing gas to the RF antenna in order to generate plasma of the processing gas by inductive coupling in the processing container;
In order to control the plasma density distribution on the substrate in the processing container, a loop independent of the RF antenna is provided and disposed outside the processing container at a position where it can be coupled to the RF antenna by electromagnetic induction. A correction coil;
Possess a switch provided in the loop of the correction coils,
The correction coil is composed of a single-turn coil or a multi-turn coil closed at both ends, and is arranged coaxially with respect to the RF antenna, and the coil conductor is positioned between the inner periphery and the outer periphery of the RF antenna in the radial direction. Having a coil diameter of
Plasma processing equipment. A processing container having a dielectric window and capable of being evacuated;
An RF antenna disposed outside the dielectric window;
A substrate holding unit for holding a substrate to be processed in the processing container;
A processing gas supply unit for supplying a desired processing gas into the processing container in order to perform a desired plasma processing on the substrate;
A high-frequency power feeding unit that supplies high-frequency power having a frequency suitable for high-frequency discharge of the processing gas to the RF antenna in order to generate plasma of the processing gas by inductive coupling in the processing container;
In order to control the plasma density distribution on the substrate in the processing container, each has a loop independent from the RF antenna, and is arranged outside the processing container at a position where it can be coupled to the RF antenna by electromagnetic induction. First and second correction coils,
Have a first and second switches are respectively provided in the loop of the first and second correction coils,
The dielectric window constitutes the ceiling of the processing vessel;
The RF antenna is disposed on the dielectric window;
The first and second correction coils are arranged in parallel with the RF antenna;
The first and second correction coils are arranged concentrically;
Plasma processing equipment. The plasma processing apparatus according to claim 5 , wherein the first and second correction coils are arranged coaxially at different height positions.

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