JP2011096690A - Plasma processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To freely and precisely control plasma density distribution by using a simple magnetic shielding member without requiring special revision to an RF antenna for plasma generation or a high frequency power supply system. <P>SOLUTION: An inductive coupling type plasma etching apparatus is configured to generate inductive coupling plasma like a donut under a dielectric window 52 in proximity to an RF antenna 54, and distribute the donut-like plasma in a wide processing space to equalize the density of the plasma in the vicinity of a susceptor 12 (i.e. on a semiconductor wafer W). The apparatus includes a magnetic shield cavity conductor 70 for shielding magnetism with an opening end downward on the RF antenna 54 in equalizing the plasma density distribution in the vicinity of the susceptor 12 in a diameter direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technique for performing plasma processing on a substrate to be processed, and more particularly to an 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. Furthermore, the plasma density distribution in the donut-shaped plasma may change depending on the high-frequency power supplied to the RF antenna, the flow rate of the processing gas introduced into the chamber, and the like. Therefore, if the magnetic field generated by the RF antenna (inductive antenna) cannot be corrected so that the uniformity of the plasma process on the substrate can be maintained even if the process conditions are changed in the process recipe, today's plasma It is impossible to meet the various and advanced process performance required for the processing equipment.

  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 supply system, and uses a simple magnetic shield member to achieve plasma density. Provided is an inductively coupled plasma processing apparatus capable of controlling the distribution freely and finely.

  An inductively coupled plasma processing apparatus according to a first aspect of the present invention includes a processing container having a dielectric window on a ceiling and capable of being evacuated; a coiled RF antenna disposed on the dielectric window; A substrate holding section for holding a substrate to be processed in the processing container; a processing gas supply section for supplying a desired processing gas into the processing container in order to perform a desired plasma processing on the substrate; In order to generate plasma of the processing gas by inductive coupling, 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 plasma density distribution on the substrate in the processing container In order to control the magnetic field, a magnetic shield cavity conductor that shields magnetism with the open end facing down on the RF antenna is provided.

  In the inductively coupled plasma processing apparatus according to the first aspect, when the high frequency power is supplied from the high frequency power feeding unit to the RF antenna by the above configuration, particularly by the configuration including the magnetic shield hollow conductor, the RF antenna In the core (usually donut-shaped) plasma generated by electromagnetic induction in the processing container inside the dielectric window due to the magnetic shielding effect of the magnetic shield cavity conductor against the RF magnetic field generated around the antenna conductor by the high-frequency current flowing through It is possible to correct the plasma density distribution.

  That is, the magnetic shield cavity conductor is typically arranged coaxially with respect to the RF antenna, and has an opening diameter such that the opening end thereof is located between the inner periphery and the outer periphery of the RF antenna in the radial direction. When the opening end of the magnetic shield cavity conductor is located between the inner peripheral edge portion and the middle portion of the RF antenna in the radial direction, it is near the opening end of the magnetic shield cavity conductor and immediately below the radially inner region. An effect of locally reducing the plasma density in the donut-shaped plasma can be obtained. Also, when the opening end of the magnetic shield cavity conductor is located between the middle portion and the outer peripheral edge portion of the RF antenna in the radial direction, it is near the opening end of the magnetic shield cavity conductor and immediately below the radially outer region. Thus, the effect of locally reducing the plasma density in the donut-shaped plasma can be obtained.

  Thus, by arbitrarily controlling the plasma density in the doughnut-shaped plasma, it is possible to arbitrarily control the plasma density distribution in the vicinity of the substrate, and the uniformity of the plasma process can be easily improved.

  An inductively coupled plasma processing apparatus according to a second aspect of the present invention includes a processing container having a dielectric window on a ceiling and capable of being evacuated, a coiled RF antenna disposed on the dielectric window, A substrate holding section for holding a substrate to be processed in the processing container; a processing gas supply section for supplying a desired processing gas into the processing container in order to perform a desired plasma processing on the substrate; In order to generate plasma of the processing gas by inductive coupling, 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 plasma density distribution on the substrate in the processing container In order to control the magnetic field, a plurality of magnetic shield hollow conductors are provided on the RF antenna for shielding magnetism with opening ends having different diameters facing downward.

  In the inductively coupled plasma processing apparatus according to the second aspect, the magnetic shielding effect of the magnetic shield cavity conductor is utilized by the configuration as described above, particularly by the configuration including a plurality of magnetic shield cavity conductors having different opening diameters. Thus, the function of arbitrarily controlling the plasma density in the donut-shaped plasma can be further improved.

  According to the inductively coupled plasma processing apparatus of the present invention, a simple magnetic shield hollow conductor can be obtained without requiring any special work on the RF antenna for generating plasma or the high-frequency power supply system due to the above configuration and operation. It is possible to control the plasma density distribution freely and finely.

It is a longitudinal cross-sectional view which shows the structure of the inductively coupled plasma etching apparatus in the 1st Embodiment of this invention. It is a figure which shows typically an example of the magnetic field distribution around a RF antenna, the magnetic flux density distribution of radial direction, and an electron density distribution in the case of not providing a magnetic shield hollow conductor. It is a figure which shows typically the electromagnetic field effect | action at the time of arrange | positioning a magnetic shield cavity conductor on RF antenna. It is a figure which shows typically the electromagnetic field effect | action when a flat conductor is arrange | positioned on an RF antenna instead of a magnetic shield hollow conductor (reference example). It is a longitudinal cross-sectional view which shows the structure of the inductively coupled plasma etching apparatus in 2nd Embodiment. It is a perspective view which shows the structure of the principal part in 2nd Embodiment. It is a figure which shows the characteristic from which the current density (plasma) density distribution of the radial direction in inductively coupled plasma changes depending on the height position (separation distance) of the magnetic shield cavity conductor with respect to RF antenna. It is a figure which shows the process of a multilayer resist method in steps. It is a figure which shows typically an example of the magnetic field distribution around a RF antenna, the magnetic flux density distribution of radial direction, and an electron density distribution in the case of not providing a magnetic shield hollow conductor. It is a figure which shows typically the electromagnetic field effect | action at the time of arrange | positioning a magnetic shield cavity conductor on RF antenna. It is a figure which shows the method of variably controlling the height position of a magnetic shield cavity conductor 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 3rd Embodiment. It is a figure which shows the characteristic from which the current density (plasma) density distribution of the radial direction in an inductively coupled plasma changes depending on the size of the opening diameter of the magnetic shield cavity conductor with respect to RF antenna. It is principal part sectional drawing which shows the principal part of the apparatus structure which enabled it to switch automatically the opening diameter of a magnetic shield cavity conductor. It is principal part sectional drawing which shows the principal part of the apparatus structure which enabled it to switch automatically the opening diameter of a magnetic shield cavity conductor. It is a perspective view which shows the structure of the principal part in 4th Embodiment. It is a figure which shows the characteristic in which the current density (plasma) density distribution of the radial direction in existing inductively coupled plasma changes. It is a cross-sectional view which shows the structure of one Example for changing the width | variety of the slit provided in a magnetic shield cavity conductor. It is a cross-sectional view which shows the structure of another Example for changing the width | variety of the slit provided in a magnetic shield cavity conductor. It is a perspective view which shows the modification of the slit provided in a magnetic shield cavity conductor. It is a longitudinal cross-sectional view which shows the structure of the inductively coupled plasma etching apparatus in 5th Embodiment. It is a figure which shows the characteristic that the current density (plasma) density distribution of the radial direction in an inductively coupled plasma changes, when one or both of an inner side and an outer side magnetic shield cavity conductor are arrange | positioned. In 6th Embodiment, it is a cross-sectional view which shows the example of 1 structure which provides a slit in both the inner side and outer side magnetic shield cavity conductors. It is a figure which shows the characteristic in which the current density (plasma) density distribution of the radial direction in an inductively coupled plasma changes, when one or both of an inner side slit and an outer side slit are opened. It is a cross-sectional view showing another configuration example in which slits are provided in both the inner and outer magnetic shield hollow conductors. It is a longitudinal cross-sectional view which shows the structure of the principal part in 7th Embodiment. It is a perspective view which shows the example of 1 structure which forms a notch in a magnetic shield cavity conductor in 7th Embodiment. It is a perspective view which shows the structure of the magnetic shield cavity conductor by one Example. It is a fragmentary sectional view which shows the principal part structure of the magnetic shield cavity conductor of FIG. 26A. It is a perspective view which shows the structure of the magnetic shield cavity conductor by another Example. It is a fragmentary sectional view which shows the principal part structure of the magnetic shield cavity conductor of FIG. 27A. It is a longitudinal cross-sectional view which shows the form of the magnetic shield cavity conductor by one Example. 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.

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

  1 to 3, a basic configuration and operation of an inductively coupled plasma processing apparatus according to the present invention will be described as a first embodiment of the present invention.

  The inductively coupled plasma processing apparatus shown in FIG. 1 is configured as an inductively coupled plasma etching apparatus using a planar coil type RF antenna. For example, a cylindrical vacuum chamber (processing vessel) made of metal such as aluminum or stainless steel is used. 10. The chamber 10 is grounded for safety.

  First, the configuration of each part not directly 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 44 extending in the circumferential direction is provided. A refrigerant having a predetermined temperature, such as cooling water, is circulated and supplied to the refrigerant chamber 44 through pipes 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. 29A) or a concentric coil (FIG. 29B) 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.

  An output terminal of a high-frequency power source 56 for generating plasma is electrically connected to one end (center end) of the RF antenna 54 via a matching unit 58 and a feed conductor (for example, a feed line) 60. The other end (outer peripheral end) of the RF antenna 54 is electrically connected to the ground potential via an earth line (return line) 55.

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 source 56 side and the impedance on the load (mainly RF antenna, plasma, and chamber) 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).

  In the inductively coupled plasma etching apparatus, in order to variably control the density distribution of inductively coupled plasma generated in the processing space in the chamber 10 in the radial direction, the inside of the antenna room 72 in the atmospheric space provided on the ceiling of the chamber 10 In addition, a magnetic shield cavity conductor 70 made of a cylindrical or dome-shaped conductor with the ceiling portion closed is disposed on the RF antenna 54 with the open end facing downward. The detailed configuration and operation of the magnetic shield cavity conductor 70 will be described 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, The individual operations of the chiller unit (not shown), the heat transfer gas supply unit (not shown), and the operation (sequence) of the entire apparatus are controlled.

In order to perform etching in this plasma etching apparatus, first, the gate valve 28 is opened, and the semiconductor wafer W to be processed is loaded into the chamber 10 and placed on the electrostatic chuck 36. Then, the gate valve 28 is closed, and an 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. And 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 high-frequency RF _H current is supplied to the RF antenna 54 via the matching unit 58 and the feeding conductor 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 hole 64 diffuses 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 plasma 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, the type of gas, and 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 inductively coupled plasma etching apparatus, in order to make the plasma density distribution in the vicinity of the susceptor 12 uniform in the radial direction, the magnetism of the magnetic shield cavity conductor 70 having a desired opening diameter with respect to the RF magnetic field generated by the RF antenna 54 is obtained. Correction is applied by the shielding effect.

  Hereinafter, the configuration and operation of the magnetic shield cavity conductor 70, which is a main characteristic part of the inductively coupled plasma etching apparatus, will be described.

  As described above, the magnetic shield cavity conductor 70 is disposed in the antenna chamber 72 above the dielectric window 52. The magnetic shield cavity conductor 70 is made of a conductor plate (for example, a copper plate) having a cylindrical portion 70a and a ceiling portion 70b, and is disposed coaxially with the RF antenna 54. Usually, the opening end thereof is the inner periphery of the RF antenna 54. And a desired opening diameter located between the outer periphery and the outer periphery. A through hole or an opening (not shown) for passing the RF power supply conductor 60 is also formed in the ceiling part 70 b of the magnetic shield cavity conductor 70.

  In the present invention, “coaxial” means a positional relationship in which the respective central axes overlap each other between a plurality of objects having an axially symmetric extension in a two-dimensional direction.

  In the antenna chamber 72, the magnetic shield cavity conductor 70 is in a horizontal posture such that the distance between the opening end of the magnetic shield cavity conductor 70 and the RF antenna 54 is constant at all positions in the azimuth direction, for example, a suspension type support member 73. Is supported by The wall portion of the antenna chamber 72 is made of a conductor such as aluminum, and is connected to the upper end of the chamber 10 and is electrically grounded. The magnetic shield cavity conductor 70 may be electrically grounded or may be in an electrically floating state.

  The basic operation of the magnetic shield cavity conductor 70 will be described with reference to FIG.

When the magnetic shield cavity conductor 70 is not disposed on the RF antenna 54, as shown in FIG. 2A, a loop shape is formed around the antenna conductor according to Ampere-Maxwell's law due to the high-frequency RF _H current flowing through the RF antenna 54. An RF magnetic field H distributed in the region is generated, and magnetic lines of force that traverse the processing space in the radial direction are formed under the dielectric window 52 even in a relatively inner (lower) region.

Here, the radial direction (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 regardless of the magnitude of the current of the high-frequency RF _H , and the middle, that is, the RF antenna It becomes a maximum at an intermediate portion between the inner diameter and the outer diameter of 54 (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 coaxial with the RF antenna 54 is formed in the processing space near the dielectric window 52.

  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. 2A, the electron density (plasma density) in the radial direction in the vicinity of the susceptor 12 rises relatively in the antenna middle portion. In some cases, a profile that falls in the center and the periphery is shown.

In such a case, as shown in FIG. 2B, when the magnetic shield hollow conductor 70 is disposed on the RF antenna 54, as shown in the figure, the high frequency RF _H current flowing through the RF antenna 54 generates around the antenna conductor. The distribution of the RF magnetic field H varies depending on the presence of the magnetic shield cavity conductor 70. That is, the magnetic field distribution is such that the magnetic field lines pass over the RF antenna 54, avoiding the magnetic shield cavity conductor 70, and the magnetic field line loop of the RF magnetic field H around the RF antenna 54 (even in the chamber below the dielectric window 52). Reduce or localize.

  In the example shown in the drawing, the opening end of the magnetic shield cavity conductor 70 is located between the antenna middle portion and the peripheral edge portion of the RF antenna 54 in the radial direction. The magnetic field line loop of the RF magnetic field H is reduced or localized just below the region (magnetic shield outer region) extending to the outer periphery in the direction, and the magnetic field strength in the chamber 10 is reduced. On the other hand, although the magnetic field line loop of the RF magnetic field H is localized immediately below the radially inner region (magnetic shield inner region) from the vicinity of the opening end of the magnetic shield hollow conductor 70, the magnetic field strength in the chamber 10 hardly decreases. .

  Due to the magnetic field shielding effect of the magnetic shield cavity conductor 70, the radial component Br of the magnetic flux density and the intensity of the induced electric field in the azimuth direction locally in the processing space inside the dielectric window 52 directly under the magnetic shield outer region. Is weakened. As a result, the electron density (plasma density) is more uniform in the radial direction in the vicinity of the susceptor 12.

  As a reference example, consider a case where a conductor plate 71 having the same diameter (diameter) as the opening diameter of the magnetic shield cavity conductor 70 is disposed on the RF antenna 54 instead of the magnetic shield cavity conductor 70. In this case, as shown in FIG. 3, in the region covered with the conductor plate 71, the RF magnetic field H generated around the antenna conductor is uniformly reduced or reduced at any position by the planar magnetic shielding effect of the conductor plate 71. Localization reduces the magnetic field strength. For this reason, the intensity distribution of the induced electric field in the azimuth direction generated by the RF magnetic field H in the processing space inside the dielectric window 52 is also uniformly reduced immediately below the region covered by the conductor plate 71. As a result, the electron density (plasma density) in the vicinity of the susceptor 12 only decreases uniformly at each position in the radial direction, and uniformity cannot be achieved.

Next, an embodiment provided with a magnetic shield cavity conductor having a more specific or practical structure in the inductively coupled plasma processing apparatus of the present invention will be described.

[Second Embodiment]

  4 to 9 show 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.

  In this inductively coupled plasma etching apparatus, the plasma density distribution in the vicinity of the susceptor 12 is made uniform in the radial direction, and the RF magnetic field generated by the RF antenna 54 is corrected by the magnetic shielding effect of the magnetic shield cavity conductor 70. At the same time, the distance between the magnetic shield hollow conductor 70 and the RF antenna 54 can be variably controlled by the antenna-magnetic shield interval control unit 76.

  In the illustrated configuration example, the cylindrical portion 70a of the magnetic shield hollow conductor 70 includes a fixed upper cylindrical portion 70a1 integrally formed or fixed to the ceiling portion 70b, and an axial direction (vertical direction) on the upper cylindrical portion 70a1. The movable lower cylindrical portion 70a2 is slidably engaged or fitted into the lower cylindrical portion 70a2.

  The antenna-magnetic shield spacing control unit 76 includes a stepping motor 80 that changes the height position of the lower cylindrical portion 70 a 2 of the magnetic shield cavity conductor 70 via the ball screw 78, and the magnetic shield cavity conductor 70 through the stepping motor 80 and the ball screw 78. And a magnetic shield height control unit 82 for variably controlling the height position of the lower cylindrical portion 70a2.

  More specifically, the lower cylindrical portion 70a2 of the magnetic shield cavity conductor 70 is coupled to the nut portion 78b of the ball screw 78 via a horizontal elevating support bar 84. The feed screw 78a of the ball screw 78 extends in the vertical direction and is coupled to the rotating shaft of the stepping motor 80 directly or via a speed reduction mechanism (not shown).

  When the stepping motor 80 is operated to rotate the feed screw 78a, the nut portion 78b moves up and down, and the lower cylindrical portion 70a2 of the magnetic shield cavity conductor 70 also moves up and down integrally with the nut portion 78b. The magnetic shield height control unit 82 receives a signal Sh indicating the height position (target value or set value) of the magnetic shield hollow conductor 70 (more precisely, the lower end of the lower cylindrical portion 70a2) from the main control unit 74, By controlling the rotation direction and the rotation amount of the stepping motor 80, the height position of the lower cylindrical portion 70a2, that is, the separation distance h from the RF antenna 54 is adjusted to the target value.

  As another embodiment of the antenna-magnetic shield interval control unit 76, a configuration in which the whole of the integrated magnetic shield cavity conductor 70 as shown in FIG. 1 is moved up and down is also possible.

  Here, the operation of the elevating magnetic shield cavity conductor 70 and the antenna-magnetic shield interval controller 76 in this embodiment will be described. The inventor conducted the following electromagnetic field simulation for the inductively coupled plasma etching apparatus of this embodiment.

  That is, the relative height position (separation distance) h of the magnetic shield hollow conductor 70 with respect to the RF antenna 54 is used as a parameter, and the value of the parameter h is 4 types of 5 mm, 10 m, 20 mm, and infinity (no magnetic shield hollow conductor). When selected, the current density distribution (corresponding to the plasma density distribution) in the radial direction inside the donut-shaped plasma (position 5 mm from the upper surface) was obtained, and a profile as shown in FIG. 6 was obtained.

In this electromagnetic field simulation, the outer diameter (radius) of the RF antenna 54 was set to 250 mm, and the cavity length, plate thickness, and opening diameter (radius) of the magnetic shield hollow conductor 70 were set to 30 mm, 5 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 86 as shown in FIG. 5, and the resistor 86 has a diameter of 500 mm and a resistivity. Was set to 100 Ωcm, and the skin thickness was set to 10 mm. The frequency of the high frequency RF _H for plasma generation was 13.56 MHz.

  As shown in FIG. 6, when the opening diameter (130 mm) of the magnetic shield cavity conductor 70 is close to or smaller than the diameter (125 mm) of the antenna middle portion of the RF antenna 54, the magnetic shield cavity conductor 70 The field line loop diameter of the RF magnetic field H is reduced or localized just below the region (magnetic shield inner region) from the vicinity of the opening end of the 70 to the radially inner center, and the magnetic field strength in the chamber 10 is reduced. On the other hand, although the magnetic field line loop of the RF magnetic field H is localized immediately below a region radially outside the vicinity of the opening end of the magnetic shield cavity conductor 70 (magnetic shield outer region), the magnetic field strength in the chamber 10 hardly decreases. .

  In this embodiment, as described above, the magnetic shield cavity conductor for the RF antenna 54 is maintained by the antenna-magnetic shield interval control unit 76 while keeping the magnetic shield cavity conductor 70 parallel (horizontal) to the horizontal RF antenna 54. Since the relative height position or the separation distance of 70 can be arbitrarily and finely varied within a certain range, the characteristics shown in FIG. 6 verified by the electromagnetic field simulation are realized in an apparatus, and the plasma density distribution is realized. The degree of freedom and accuracy of control can be greatly improved.

  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. 7 will be described below.

  In FIG. 7, an 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. 7B, 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. 7C and 7D, 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 magnetic shield cavity conductor 70 is not provided, in the first and second step processes (pressure 10 mTorr or less), the electron density (plasma density) in the vicinity of the susceptor 12 is relatively centered as shown in FIG. 3A. It is assumed that a steep mountain-shaped profile that rises remarkably appears, and a gentle mountain-shaped profile that slightly rises in the center appears in the third step process (pressure 50 mTorr).

  According to this embodiment, in a process recipe, for example, in a manner that is added to or associated with normal process conditions (high frequency power, pressure, gas type, gas flow rate, etc.) The height position is set as one of recipe information or process parameters. When the multi-step etching process as described above is executed, the main control unit 74 reads out data representing the height position setting value of the magnetic shield cavity conductor 70 from the memory, and controls the magnetic shield height for each step. The height position of the magnetic shield cavity conductor 70 is adjusted to a set value (target value) through the portion 80.

Therefore, in the etching process of the multilayer resist method as described above (FIG. 7), as shown in FIG. 9, the first step (10 mTorr) is set at a relatively low setting position h ₁ and the second step (5 mTorr) is further reduced. In the third step (50 mTorr), the height position of the magnetic shield cavity conductor 70 is switched to the lower position h ₂ for each step to the relatively higher position h ₃ .

As described above, the height position of the magnetic shield cavity conductor 70 can be variably adjusted in accordance with the change, changeover or change of the process conditions while performing a single or a series of plasma processes on one semiconductor wafer W. It is. Thus, the magnetic shielding effect of the magnetic shield cavity conductor 70 against the RF magnetic field H generated around the antenna conductor by the high frequency RF _H current flowing through the RF antenna 54 throughout the entire processing time or step of the single wafer plasma process, that is, The degree (intensity) of the effect of locally reducing the plasma density in the donut-shaped plasma just below the open end of the magnetic shield cavity conductor 70 and directly below the radially inner region (or radially outer region) It is possible to adjust linearly, and thereby, the plasma density in the vicinity of the susceptor 12 can be kept uniform in the radial direction. Therefore, the uniformity of the plasma process can be improved.

In the multi-step method, while the etching process is not performed, the height position of the magnetic shield cavity conductor 70 is substantially equal to the home position when there is no magnetic shield cavity conductor 70 as shown in FIG. it may be allowed to return to the h _P.

In this embodiment, as described above, the antenna-magnetic shield interval control unit 76 for variably adjusting the separation distance or height position of the magnetic shield hollow conductor 70 with respect to the RF antenna 54 is configured by a ball screw mechanism. However, instead of the ball screw mechanism, a three-dimensional cam mechanism such as a rotating body cam or an end cam can be used. That is, although the detailed configuration is not shown, as another embodiment of the antenna-magnetic shield interval control unit 76, the magnetic shield cavity conductor 70 is coupled via a solid cam mechanism having a rotating body. A motor that rotates the rotating body to change the height position of the magnetic shield cavity conductor 70, and a coil height controller that controls the height position of the magnetic shield cavity conductor 70 by controlling the rotation direction and amount of rotation of the motor. It is also possible to have a configuration with

[Third Embodiment]

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

  FIG. 10 shows the configuration of an inductively coupled plasma etching apparatus according to the third embodiment. In the drawing, parts having the same configuration or function as those of the apparatus of the first or second embodiment (FIGS. 1 and 4) described above are denoted by the same reference numerals.

  The unique feature of the third embodiment is that the opening diameter of the magnetic shield cavity conductor 70 can be varied. In the apparatus configuration example of FIG. 10, a plurality (for example, three types) of magnetic shield hollow conductors 70 (1), 70 (2), and 70 (3) having different opening diameters are prepared, and any one of them is selected. Then, it is detachably attached to the suspension type support member 73.

  The inventor conducted the following electromagnetic field simulation for the inductively coupled plasma etching apparatus of this embodiment.

  That is, the radius (radius) R of the magnetic shield cavity conductor 70 is used as a parameter, and the value of the parameter R is selected from four types of 100 mm, 130 m, 170 mm, and 200 mm, and the radius inside the donut-shaped plasma (position 5 mm from the upper surface). When the current density distribution in the direction (corresponding to the plasma density distribution) was obtained, a profile as shown in FIG. 11 was obtained.

In this electromagnetic field simulation, the outer diameter (radius) of the RF antenna 54 was set to 250 mm, and the cavity length and plate thickness of the magnetic shield cavity conductor 70 were set to 30 mm and 5 mm, respectively. The separation distance h between the RF antenna 54 and the magnetic shield hollow conductor 70 was set to 5 mm. Further, 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 86 similar to that shown in FIG. Was set to 500 mm, the resistivity was set to 100 Ωcm, and the skin thickness was set to 10 mm. The frequency of the high frequency RF _H for plasma generation was 13.56 MHz.

  As shown in FIGS. 11A and 11B, when the opening diameter of the magnetic shield hollow conductor 70 is larger than the diameter (125 mm) of the antenna middle portion of the RF antenna 54 (R = 200 mm, 170 mm), the magnetic It can be seen that the plasma density in the donut-shaped plasma is locally reduced just below the opening end of the shield cavity conductor 70 and the region (magnetic shield outer region) extending to the outer periphery in the radial direction.

  On the other hand, as shown in FIGS. 11C and 11D, when the opening diameter of the magnetic shield cavity conductor 70 approximates the diameter (125 mm) of the antenna middle portion of the RF antenna 54 (R = 130 mm). Or smaller (R = 100 mm), in the donut-shaped plasma just below the opening end of the magnetic shield cavity conductor 70 and directly below the region (magnetic shield inner region) toward the radially inner center. It can be seen that the plasma density decreases locally.

  In the apparatus configuration example of FIG. 10, the opening diameter of the magnetic shield cavity conductor 70 can be changed by a manual attachment / detachment exchange type, but a configuration in which it can be changed by an automatic switching type as schematically shown in FIGS. Is possible.

  12 and FIG. 13 shows the above three types of magnetic shield cavity conductors 70 (1), 70 (2), 70 (3) having different opening diameters divided and raised in the same manner as the magnetic shield cavity conductor 70 of FIG. A mold is formed, and any one (or a plurality) of them is selected and lowered to the vicinity of the RF antenna 54. As shown in FIGS. 12 and 13, a configuration in which the top plate (ceiling wall) of the antenna chamber 72 also serves as the ceiling portion of the magnetic shield cavity conductor 70 is possible. In the illustrated example, the top plate (ceiling wall) of the antenna chamber 72 also serves as the ceiling of all the magnetic shield hollow conductors 70 (1), 70 (2), and 70 (3), but a part of them. It is also possible to use a configuration that only serves as a combination.

In this embodiment, as described above, since the opening diameter of the magnetic shield cavity conductor 70 can be varied, the characteristics shown in FIG. 11 verified by the electromagnetic field simulation are realized in an apparatus, and the plasma density distribution control is free. The degree and accuracy can be greatly improved.

[Fourth Embodiment]

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

  FIG. 14 shows the configuration of the magnetic shield cavity conductor 70 used in the inductively coupled plasma etching apparatus according to the fourth embodiment.

  The unique feature of the fourth embodiment is that a large number of slits 110 extending in the vertical direction are provided in the cylindrical portion 70a of the magnetic shield cavity conductor 70 at regular intervals in the azimuth direction. As shown in FIG. 14, the slit 110 is typically formed to extend straight from the lower end to the upper end of the magnetic shield cavity conductor 70 with a constant slit width S.

  The inventor conducted the following electromagnetic field simulation for the inductively coupled plasma etching apparatus of this embodiment.

  That is, the width S of the slit 110 provided in the magnetic shield cavity conductor 70 is used as a parameter, and the value of the parameter S is selected from 0 mm (aperture ratio 0%), 2 m, 5 mm, and 20 mm. When the current density distribution in the radial direction (corresponding to the plasma density distribution) at a position 5 mm from the center was obtained, a profile as shown in FIG. 15 was obtained.

In this electromagnetic field simulation, the outer diameter (radius) of the RF antenna 54 was set to 250 mm, and the cavity length, plate thickness, and opening diameter (radius) of the magnetic shield hollow conductor 70 were set to 30 mm, 5 mm, and 130 mm, respectively. The number of slits 110 was 18 at 20 ° intervals in the azimuth direction. In this case, the slit width of 20 mm corresponds to an aperture ratio of 45%. Here, an aperture ratio of 0% is equivalent to the absence of the slit 110, and an aperture ratio of 100% is equivalent to the absence of the magnetic shield cavity conductor. The separation distance h between the RF antenna 54 and the magnetic shield hollow conductor 70 was set to 5 mm. 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 86 as shown in FIG. 14, and the resistor 86 has a diameter of 500 mm and a resistivity. Was set to 100 Ωcm, and the skin thickness was set to 10 mm. The frequency of the high frequency RF _H for plasma generation was 13.56 MHz.

  As shown in FIG. 15, as the width S of the slit 110 is increased, the magnetic shielding effect of the magnetic shield cavity conductor 70, that is, near the opening end of the magnetic shield cavity conductor 70 and its radial inner side (or its radial outer side). The effect of locally reducing the plasma density in the donut-shaped plasma just below the region is weakened. That is, it can be seen that by changing the width S of the slit 110 of the magnetic shield cavity conductor 70, the same effect as that obtained when the height position of the magnetic shield cavity conductor 70 is changed (FIG. 6) can be obtained.

  FIG. 16 shows an embodiment for changing the width S of the slit 110 of the magnetic shield cavity conductor 70. In this embodiment, a cylindrical body having slits 112 of the same number, the same size, and the same interval as the slits 110 of the magnetic shield cavity conductor 70 on the radially inner side of the magnetic shield cavity conductor 70 is used as a shutter or an aperture ratio adjusting member 114 as an azimuth angle. It is attached so that it can move in the direction (circumferential direction), that is, can be rotationally displaced. In this case, the portion [110, 112] where the slit 112 of the aperture ratio adjusting member 114 overlaps the slit 110 of the magnetic shield hollow conductor 70 has a substantial slit width.

  When the aperture ratio adjusting member 114 is rotationally displaced in the circumferential direction, the substantial slit width [110, 112] can be fully opened as shown in FIG. 16A, or as shown in FIG. 16B. It can be half open or fully closed as shown in FIG.

  FIG. 17 shows another embodiment for varying the width S of the slit 110 of the magnetic shield cavity conductor 70. In this embodiment, the cylindrical portion of the magnetic shield hollow conductor 70 has a large number (n) of strip-shaped plates 116 (1), 116 (2), 116 (3),..., 116 (n) in the azimuth direction. Each of the strip-shaped plate bodies 116 (1) to 116 (n) is configured to be rotatable and displaceable about a rotation axis (not shown) extending in the longitudinal direction. Thereby, the slit 110 of the magnetic shield hollow conductor 70 can be closed as shown in FIG. 17A or can be opened as shown in FIG.

  Furthermore, as another modified example, as shown in FIG. 18, it has an arbitrary width A, an arbitrary height position B, and an arbitrary total length C, limited to the lower end portion of the cylindrical portion 70a of the magnetic shield hollow conductor 70. A configuration in which a large number of openings 118 are provided at regular intervals in the azimuth direction is also possible.

In this embodiment, as described above, a large number of slits 110 are provided in the magnetic shield cavity conductor 70 at regular intervals in the azimuth direction so that the slits 110 can be opened and closed, or the slit width or aperture ratio of the slits 110 is set. Since it is made variable, the characteristics shown in FIG. 15 verified by electromagnetic field simulation are realized in an apparatus, and the plasma density distribution in the donut-shaped plasma generated in the processing space near the dielectric window 52 can be arbitrarily set in the radial direction. Thus, the plasma density distribution in the vicinity of the susceptor 12 can be arbitrarily controlled in the radial direction.

[Fifth Embodiment]

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

  FIG. 19 shows a configuration of a magnetic shield cavity conductor 70 used in the inductively coupled plasma etching apparatus according to the fifth embodiment.

  In the fifth embodiment, the magnetic shield cavity conductor 70 includes a plurality (for example, two) of magnetic shield cavity conductors 70A and 70B having different opening diameters. In the third embodiment (FIGS. 12 and 13) described above, usually one of a plurality of types of magnetic shield hollow conductors 70 (1), 70 (2), and 70 (3) having different opening diameters is used. In contrast to this, in the fifth embodiment, the inner magnetic shield cavity conductor 70A and the outer magnetic shield cavity conductor 70B function constantly (multiple) together.

  The inventor conducted the following electromagnetic field simulation for the inductively coupled plasma etching apparatus of this embodiment.

  That is, as the magnetic shield cavity conductor 70, only the inner magnetic shield cavity conductor 70A is provided, only the outer magnetic shield cavity conductor 70B is provided, and both the inner and outer magnetic shield cavity conductors 70A and 70B are provided. When the current density distribution (corresponding to the plasma density distribution) in the radial direction inside the donut-shaped plasma (position 5 mm from the upper surface) was determined for the three types, a profile as shown in FIG. 20 was obtained.

In this electromagnetic field simulation, the outer diameter (radius) of the RF antenna 54 is set to 250 mm, the cavity length, plate thickness, and opening diameter (radius) of the inner magnetic shield hollow conductor 70A are set to 30 mm, 5 mm, and 100 mm, respectively. The cavity length, plate thickness, and opening diameter (radius) of the shield cavity conductor 70B were set to 30 mm, 5 mm, and 170 mm, respectively. The separation distance h between the RF antenna 54 and the magnetic shield hollow conductors 70A and 70B was set to 5 mm. 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 86 as shown in FIG. 19, and the resistor 86 has a diameter of 500 mm and a resistivity. Was set to 100 Ωcm, and the skin thickness was set to 10 mm. The frequency of the high frequency RF _H for plasma generation was 13.56 MHz.

  From FIG. 20, in the case where only the inner (opening radius 100 mm) magnetic shield cavity conductor 70A is provided, the plasma density decreases from the center in the donut-shaped plasma to the antenna middle, and the outer (opening radius 170 mm) magnetic shield cavity. When only the conductor 70B is provided, the plasma density decreases from the middle portion to the peripheral portion in the doughnut-shaped plasma, and when the inner and outer magnetic shield hollow conductors 70A and 70B are provided together, It can be seen that the plasma density decreases from the center to the periphery.

Although not shown, it is also possible to provide a mechanism for individually varying the height positions of the inner and outer magnetic shield hollow conductors 70A and 70B.

[Sixth Embodiment]

  The sixth embodiment of the present invention is a combination of the fourth and fifth embodiments described above, and is characterized in that slits 110A and 110B are provided in the inner and outer magnetic shield cavity conductors 70A and 70B, respectively. .

  As a preferred embodiment, as shown in FIG. 21, the aperture ratio adjusting members 114A and 114B are respectively attached to the inner and outer magnetic shield hollow conductors 70A and 70B, and the aperture ratio adjusting members 114A and 114B are rotationally displaced in the circumferential direction. Thus, the slits 110A and 110B can be opened and closed, or the slit widths or aperture ratios of the slits 110A and 110B can be varied. In FIG. 21, the inner slit 110A is fully opened, and the outer slit 110B is fully closed.

  The inventor conducted the following electromagnetic field simulation for the inductively coupled plasma etching apparatus of this embodiment.

  That is, when both the slit 110A of the inner magnetic shield cavity conductor 70A and the slit 110B of the outer magnetic shield cavity conductor 70B are fully opened (a), the slit 110A of the inner magnetic shield cavity conductor 70A is completely closed and the outer magnetic shield cavity is closed. When the slit 110B of the conductor 70B is fully opened (b), when the slit 110A of the inner magnetic shield cavity conductor 70A is fully opened and the slit 110B of the outer magnetic shield cavity conductor 70B is completely closed (c), the donut-shaped plasma When the current density distribution in the radial direction (corresponding to the plasma density distribution) inside (at a position 5 mm from the upper surface) was obtained, a profile as shown in FIG. 22 was obtained.

In this electromagnetic field simulation, the outer diameter (radius) of the RF antenna 54 was set to 250 mm, and the cavity lengths and plate thicknesses of the inner and outer magnetic shield cavity conductors 70A and 70B were set to 30 mm and 5 mm, respectively. The number of slits 110A and 110B was 18 at 20 ° intervals in the azimuth direction, and the width of the slits 110A and 110B was 10 ° in terms of angle. In this case, the slit fully open state corresponds to an aperture ratio of 50%. Here, an aperture ratio of 100% is equivalent to the absence of the magnetic shield cavity conductors 70A and 70B. The separation distance h between the RF antenna 54 and the magnetic shield hollow conductor 70 was set to 5 mm. 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 86 similar to that shown in FIG. 19, and the diameter of the resistor 86 is 500 mm. The resistivity was set to 100 Ωcm and the skin thickness was set to 10 mm. The frequency of the high frequency RF _H for plasma generation was 13.56 MHz.

  As shown in FIG. 22B, when the slit 110A of the inner magnetic shield cavity conductor 70A is closed and the slit 110B of the outer magnetic shield cavity conductor 70B is opened, the region from the center to the middle in the donut-shaped plasma The plasma density is significantly reduced.

  As shown in FIG. 22C, when the slit 110A of the inner magnetic shield cavity conductor 70A is opened and the slit 110B of the outer magnetic shield cavity conductor 70B is closed, the region from the middle portion to the peripheral portion in the donut-shaped plasma is obtained. The plasma density is significantly reduced.

  As shown in FIG. 22 (a), when the slit 110A of the inner magnetic shield cavity conductor 70A and the slit 110B of the outer magnetic shield cavity conductor 70B are both opened, almost all of the center portion in the donut-shaped plasma is centered. There is some reduction in plasma density over the region.

  In the configuration example of FIG. 21, the slits 110A of the inner magnetic shield cavity conductor 70A and the slits 110B of the outer magnetic shield cavity conductor 70B are arranged in the same phase (positions that overlap in the azimuth direction). As a modification, as shown in FIG. 23, each slit 110A of the inner magnetic shield cavity conductor 70A and each slit 110B of the outer magnetic shield cavity conductor 70B are arranged in opposite phases (positions that do not overlap in the azimuth direction). It is also possible.

As described above, in this embodiment, the open / close state of the slits 110A and 110B provided in the inner and outer magnetic shield hollow conductors 70A and 70B is switched, or the slit width or aperture ratio of the slits 110A and 110B is changed. Thus, the plasma density distribution in the donut-shaped plasma generated in the processing space near the dielectric window 52 can be arbitrarily controlled in the radial direction, and the plasma density distribution in the vicinity of the susceptor 12 can be arbitrarily controlled in the radial direction. .

[Seventh Embodiment]

  The seventh embodiment of the present invention is characterized by having a magnetic shield rotating mechanism 120 for rotating the magnetic shield hollow conductor 70 at a position coaxial with the RF antenna 54.

  In this magnetic shield rotating mechanism 120, as shown in FIG. 24, the ceiling portion of the magnetic shield hollow conductor 70 is configured by the top plate (ceiling wall) of the antenna chamber 72, and is connected to or integrally formed with the upper end of the cylindrical portion 70a. The magnetic shield cavity conductor 70 is configured to be rotatable by engaging the annular flange portion 70 c with the annular guide rail 122 attached to the antenna chamber 72. A ring-shaped internal gear 124 is attached to the inner wall of the cylindrical portion 70 a of the magnetic shield cavity conductor 70, and the gear 126 coupled to the rotation drive shaft of the motor 128 is engaged with the internal gear 124. The magnetic shield cavity conductor 70 can be rotated at a constant speed through the gear 126 and the internal gear 124 by the rotational driving force of the motor 128.

  In this embodiment, preferably, as shown in FIG. 25, a notch portion 130 having a desired size (for example, 10 ° to 60 ° in terms of angle) in the azimuth direction is formed in the cylindrical portion 70a of the magnetic shield hollow conductor 70. May be provided. When such a notch 130 is provided in the magnetic shield cavity conductor 70, if the magnetic shield cavity conductor 70 is stationary, the magnetic field of the magnetic shield cavity conductor 70 with respect to the RF magnetic field H formed around the RF antenna 54. The shielding effect is biased in the azimuth direction, and the plasma density distribution is biased in the azimuth direction. However, by rotating the magnetic shield cavity conductor 70, the deviation in the azimuth direction can be canceled and smoothed.

According to this embodiment, it is possible to adjust the strength of the magnetic field shielding action of the magnetic shield cavity conductor 70 according to the size of the notch 130, which is similar to changing the height position of the magnetic shield cavity conductor 70. The effect of can be obtained.

[Other Embodiments or Modifications]

  For example, in the inductively coupled plasma processing apparatus (FIG. 4) in the second embodiment described above, when the height position of the magnetic shield cavity conductor 70 is changed, a magnetic field is generated between the inside and the outside of the magnetic shield cavity conductor 70 in the radial direction. The intensity ratio (or difference) changes, and the magnetic field intensity ratio increases as the height position of the magnetic shield cavity conductor 70 decreases, that is, as the distance from the RF antenna 54 decreases.

From the opposite point of view, as shown in FIG. 4, a magnetic field sensor 130, 132 disposed respectively inside and outside the magnetic shield cavity conductor 70, which output signal of the magnetic field sensor 130, 132 (field strength measurement value) M _in , _Mout may be fed back to the magnetic shield height controller 82. For example, the height position of the magnetic shield cavity conductor 70 can be adjusted so that the ratio of M _in and M _out becomes a specified value.

In addition, when the slit 110 is provided in the magnetic shield cavity conductor 70 and the width or the aperture ratio of the slit can be arbitrarily variably controlled using an actuator such as a motor, the output signals (magnetic field strength) of the magnetic field sensors 130 and 132 are used. It is also possible to feed back the measured values M _in and M _out to the aperture ratio control unit and control the aperture ratio so that the ratio of M _in and M _out becomes a specified value.

  26A and 26B show an embodiment relating to the structure of the magnetic shield cavity conductor 70. FIG. The magnetic shield cavity conductor 70 has an upper holding ring 134H and a lower holding ring 134L having a U-shaped cross section facing each other in parallel, and a cylindrical metal mesh 136 that can be expanded and contracted in the vertical direction between the holding rings 134H and 134L. It is provided. In such a configuration, the space between the upper holding ring 134H and the lower holding ring 134L can be arbitrarily changed, and the cavity length of the magnetic shield cavity conductor 70 can be varied.

  Further, as shown in FIGS. 27A and 27B, as a modification, a cylindrical metal mesh may be formed of a strip-shaped conductor plate 138.

  As shown in FIG. 28, a dome shape is possible as an example of the configuration of the magnetic shield cavity conductor 70.

  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, as a basic form of the RF antenna and the correction antenna, a type other than the planar shape, such as a dome shape, is possible. In the planar shape or the dome shape, the opening diameter of the magnetic shield cavity conductor may be smaller than the inner diameter of the RF antenna or larger than the outer diameter of the RF antenna.

  Further, a chamber structure for a rectangular substrate, a rectangular RF antenna structure, and a rectangular cylindrical magnetic shield hollow conductor structure are also possible.

A configuration in which the processing gas is introduced into the chamber 10 from the ceiling in the processing gas supply unit is also possible, and a configuration in which the high frequency RF _L for DC bias control is not applied to the susceptor 12 is also possible. 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.

  In addition, when processing gas is introduced into the chamber 10 from the ceiling, a through hole or an opening for allowing the gas pipe to pass through the magnetic shield cavity conductor 70 is provided.

  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.

Claims (25)

A processing vessel having a dielectric window on the ceiling and capable of being evacuated;
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;
A plasma processing apparatus comprising: a magnetic shield cavity conductor that shields magnetism with an open end facing down on the RF antenna in order to control a plasma density distribution on the substrate in the processing container.   The plasma processing apparatus according to claim 1, wherein the magnetic shield hollow conductor has a cylindrical or dome-shaped shape with a ceiling portion closed. The magnetic shield cavity conductor is accommodated in an antenna room of an atmospheric pressure space provided on the RF antenna,
The ceiling wall of the antenna room constitutes the ceiling of the magnetic shield cavity conductor;
The plasma processing apparatus according to claim 1 or 2.   The plasma processing apparatus according to claim 1, wherein the magnetic shield cavity conductor is disposed such that an opening end thereof is spaced apart from the RF antenna along a azimuth direction by a certain distance.   The magnetic shield cavity conductor is disposed coaxially with respect to the RF antenna, and has an opening diameter such that an opening end thereof is positioned between an inner periphery and an outer periphery of the RF antenna in a radial direction. 5. The plasma processing apparatus according to claim 4.   The plasma processing apparatus according to claim 1, wherein the magnetic shield cavity conductor has a variable opening diameter with respect to the RF antenna.   The 1st through-hole for letting the RF electric power feeding conductor which flows the high frequency electric current from the said high frequency electric power feeding part to the said RF antenna is provided in the said magnetic shield hollow conductor in any one of Claims 1-6. The plasma processing apparatus as described.   8. The second through hole for passing a gas pipe for supplying a processing gas from the processing gas supply unit into the processing container is provided in the magnetic shield cavity conductor. The plasma processing apparatus according to item.   The plasma processing apparatus according to any one of claims 1 to 8, wherein a plurality of slits extending in a vertical direction are provided in the magnetic shield cavity conductor at a desired interval in an azimuth direction.   The plasma processing apparatus according to claim 9, further comprising a shutter for opening and closing the slit.   The plasma processing apparatus according to claim 9, further comprising an aperture ratio adjusting unit for changing a width of an opening portion of the slit.   First and second magnetic field strength measuring units for measuring the magnetic field strength inside and outside the magnetic shield hollow conductor, respectively, and obtained by the first and second magnetic field strength measuring units, respectively. The second magnetic field strength measurement value is fed back to the aperture ratio control unit so that the ratio of the first magnetic field strength measurement value and the second magnetic field strength measurement value becomes a specified value. The plasma processing apparatus according to claim 11, wherein the width of the portion is controlled.   The plasma processing apparatus according to claim 1, further comprising an antenna-magnetic shield interval control unit that variably controls a separation distance between the RF antenna and the magnetic shield hollow conductor.   First and second magnetic field strength measuring units for measuring the magnetic field strength inside and outside the magnetic shield hollow conductor, respectively, and obtained by the first and second magnetic field strength measuring units, respectively. The second magnetic field strength measurement value is fed back to the antenna-magnetic shield interval control unit so that the ratio between the first magnetic field strength measurement value and the second magnetic field strength measurement value becomes a specified value. The plasma processing apparatus according to claim 13, wherein a separation distance between an RF antenna and the magnetic shield hollow conductor is controlled.   The plasma processing apparatus according to claim 1, further comprising: a magnetic shield rotating mechanism for rotating the magnetic shield hollow conductor at a position coaxial with the RF antenna.   The plasma processing apparatus according to claim 15, wherein the magnetic shield cavity conductor has a notch portion that biases the plasma density distribution in the azimuth direction in a stationary state. A processing vessel having a dielectric window on the ceiling and capable of being evacuated;
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 container, the plasma processing includes: a plurality of magnetic shield hollow conductors that shield the magnetism with the opening ends having different diameters facing down on the RF antenna. apparatus.   The plasma processing apparatus according to claim 17, wherein each of the plurality of magnetic shield hollow conductors has a cylindrical or dome-shaped shape with a ceiling portion closed. The plurality of magnetic shield hollow conductors are accommodated in an antenna room of an atmospheric pressure space provided on the RF antenna,
The ceiling wall of the antenna chamber constitutes the ceiling of at least one magnetic shield cavity conductor;
The plasma processing apparatus according to claim 17 or claim 18.   The plurality of magnetic shield hollow conductors are coaxial with the RF antenna and are arranged concentrically with each other, and each open end is positioned between the inner periphery and the outer periphery of the RF antenna in the radial direction. The plasma processing apparatus as described in any one of Claims 17-19 which has a diameter.   The plasma processing apparatus according to any one of claims 15 to 17, further comprising an antenna-magnetic shield interval control unit that variably controls the separation distances of the plurality of magnetic shield hollow conductors from the RF antenna.   The plasma processing apparatus according to any one of claims 17 to 21, wherein a plurality of slits extending in a vertical direction are provided in each of the plurality of magnetic shield hollow conductors at a desired interval in an azimuth direction.   The plasma processing apparatus according to claim 22, further comprising a shutter for opening and closing the slit.   The plasma processing apparatus according to claim 22, further comprising an aperture ratio adjustment unit configured to change a width of an opening portion of the slit.   The plasma processing apparatus according to any one of claims 22 to 24, wherein the same number of slits are provided in the plurality of magnetic shield hollow conductors.