JP6235293B2 - Plasma processing equipment - Google Patents

Description

  The present invention relates to a plasma processing apparatus for processing a wafer placed on an upper surface of a sample stage disposed in a processing chamber using plasma formed in a processing chamber inside the plasma processing apparatus.

  Japanese Unexamined Patent Publication No. 2008-251681 (Patent Document 1) is known as a conventional technique of the plasma processing apparatus as described above. In this prior art, cables and piping for RF, He gas for cooling the back of the wafer, and coolant for cooling the sample table are arranged in a space communicating with the outside inside the sample table, and the wafer is moved up and down in this space. A pusher pin and a base member that supports the pusher pin at its lower end are arranged under atmospheric pressure. Each of these pipes and cables was connected to the bottom surface of the sample table base material constituting the top surface of the space at different positions. Further, since the pusher pins pass through the pusher holes communicating with the processing chamber, bellows for airtightly partitioning the atmospheric pressure space are arranged around each pin.

JP 2008-251681 A

  The above prior art has a problem because the following points are not sufficiently considered. In other words, the above-described prior art is configured so that the position of the sample stage is fixed in the vertical direction in the processing chamber, and the above-described pusher pins, cables, and pipes are arranged at appropriate positions on the sample stage where the vertical position varies. Was insufficient.

  In particular, the member that supports the sample stage disposed in the center of the processing chamber must move up and down in order to move the sample stage up and down. Furthermore, the sample stage is required to move up and down while the pipe and the cable are connected and the pusher pin is held at a predetermined relative position. Furthermore, in recent years, wafer processing temperature conditions have expanded, temperature uniformity has been improved, and setting of temperature in a short time is required. Therefore, it is possible to mount heaters and electrostatic adsorption electrodes on multiple sample stands. It has been demanded.

  In this way, the above-described prior art has not taken into consideration the arrangement suitable for connecting a plurality of cables and pipes below the moving sample table.

  An object of the present invention is to provide a plasma processing apparatus provided with a highly reliable sample stage in which pusher pins, cables and piping for supplying power and cooling fluid are appropriately arranged.

The above purpose is a processing chamber that is disposed inside a vacuum vessel and whose inside is decompressed,
An exhaust pump for reducing the pressure by exhausting disposed processing chamber below the vacuum chamber,
Disposed in the processing chamber, comprising: a sample stage on which the wafer to be processed is mounted on the upper surface thereof, the
A plasma processing apparatus,
Arranged inside the sample stage, and a plurality of pins for supporting the wafer in spaced or the upper surface from the upper surface by moving the wafer in the vertical direction relative to the sample stage upper surface placed on the tip,
Are connected at the bottom and the center of the sample stage, a hollow shaft for supporting the sample stage in the processing chamber, a first shaft arranged through a through hole disposed in the vacuum container,
The said through hole at the outer peripheral side of the first axis is arranged as the first axis coaxial with a second axis of the hollow which is connected to the plurality of pins,
A bellows flange disposed on and connected to the outer periphery of the second shaft, and connected to the plurality of pins;
Between and between the underside and the inner wall surface of the vacuum vessel of the bellows flange and the upper surface of inside the bellows flange and the sample stage of the lower surface of the vacuum vessel, and the outer periphery of the second shaft and the through hole Two bellows that are placed around and extendable in the vertical direction,
Between the inner wall surface of the periphery of the through hole of the lower surface and the vacuum chamber upper and lower ends and of the sample stage of these bellows, said bellows being equal pressure and atmospheric pressure through the through hole Sealing means for hermetically sealing a space between the inside of the vacuum vessel and the inside of the vacuum container that has been decompressed ;
The plurality of pins arranged in the vertical direction between the outer wall surface of the first shaft and the inner wall surface of the second shaft, and the second shaft and the plurality of pins connected to the second shaft with respect to the first shaft. This is achieved by a plasma processing apparatus including a guide bearing that is slidably movable in the vertical direction.

  In the above plasma processing equipment, the pusher pin operation mechanism, cable, and piping are placed in a space that is at atmospheric pressure to prevent the processing gas and deposits from entering the pusher pin operation mechanism and cable / pipe connection, and pusher pin operation It can prevent galling and deterioration of cable / pipe connections.

Diagram showing the configuration of the vacuum processing chamber Diagram showing the configuration of the sample stage AA sectional view of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a longitudinal sectional view schematically showing the configuration of a plasma processing apparatus according to an embodiment of the present invention.

  In FIG. 1, the plasma processing apparatus is roughly divided into a vacuum container 1 which is a container having a cylindrical portion, and a processing gas which is disposed above the vacuum container 1 and is supplied into the vacuum container 1. A discharge unit 3 for supplying an electric field or a magnetic field to discharge to generate plasma, and an exhaust such as a turbo molecular pump that is connected to the discharge unit 3 below the vacuum vessel 1 and exhausts to depressurize the inside of the vacuum vessel 1 And an exhaust part including the pump 2. Further, the vacuum vessel 1 has a gate which is an opening through which a substrate-like sample such as a semiconductor wafer to be processed passes through the inside, and an outer wall surface surrounding the gate is placed in a decompressed inside. The wafer is connected to a vacuum transfer container which is another vacuum container having a transfer chamber 4 in which the wafer is mounted on the arm of the arranged transfer robot and in which the wafer is transferred.

  The vacuum vessel 1 has a processing chamber in which plasma is formed and a wafer is processed by the plasma. The processing chamber has a discharge chamber in which a plasma is formed with a cylindrical shape at the top, and a space around the cylindrical sample stage 5 below the discharge chamber, such as gas and plasma in the discharge chamber. It has an exhaust space for exhausting particles.

  A plurality of gas introduction holes for introducing processing gases from a gas source (not shown) are arranged on the ceiling surface of the processing chamber above the wafer mounting surface of the sample stage 5 and connected to the lower surface of the vacuum vessel 1. Further, an exhaust port communicating between the exhaust pump 2 and the inside of the processing chamber is disposed at the lower portion of the processing chamber at a position spaced in a horizontal direction (right side in the drawing) from the sample stage 5 below the discharge chamber. Due to the balance between the introduction of gas from the gas introduction hole and the discharge of gas by the exhaust pump 2, the pressure inside the processing chamber is maintained at a degree of vacuum suitable for the formation of plasma and the processing by this.

  The discharge unit 3 disposed above and outside the discharge chamber of the vacuum vessel 1 includes a waveguide that propagates the formed electric field and introduces it into the inside from above the discharge chamber, a lower portion of the waveguide, and a discharge chamber. And a solenoid coil for supplying a magnetic field to the inside of the discharge chamber. The waveguide has a cylindrical portion extending in the vertical direction, an upper end of the cylindrical portion, and a rectangular portion having a rectangular cross section extending in the horizontal direction by connecting one end of the cylindrical portion. A magnetron formed by oscillating a microwave electric field is disposed on the end side portion.

  At the lower end of the cylindrical part is a cylindrical chamber having a large radius, and a resonance chamber in which the intensity of the electric field of the microwave introduced by propagation inside is increased in a specific mode is arranged. The lower surface is formed by the upper surface of a dielectric disc that transmits a microwave electric field or magnetic field, such as quartz, that constitutes the upper cover of the vacuum vessel 1 above the discharge chamber. In addition, a shower plate, which is a dielectric disc that is arranged below the disc and is spaced from the disc to constitute the ceiling surface of the discharge chamber and transmits an electric field or a magnetic field and in which the gas introduction hole is arranged, is provided. Has been placed.

  In such a plasma processing apparatus, when it is detected that the pressure inside the processing chamber and the pressure inside the transfer chamber 4 are substantially the same, the gate is opened or airtightly disposed inside the transfer chamber 4. The gate valve to be sealed is released, and the transfer chamber 4 and the processing chamber are communicated with each other. Next, the arm of the transfer robot is extended and placed on the arm, the wafer is carried into the processing chamber, and placed on the tips of a plurality of pins protruding above the upper surface of the sample table 5 and delivered.

  After the arm contracts and leaves the processing chamber, when the plurality of pins move downward and are stored up to the tip in the sample table 5, the wafer is placed in contact with the mounting surface of the sample table 5. The processing chamber and the transfer chamber 4 are airtightly partitioned by the gate valve. Thereafter, the wafer is placed on the top surface of a dielectric film that constitutes the placement surface on the sample stage 5 and is attracted and held by electrostatic force. In this state, gas is introduced into the discharge chamber from the gas introduction hole of the shower plate. As described above, the balance between the introduction amount of the treatment gas and the exhaust amount by the exhaust pump 2 causes the inside of the treatment chamber, particularly the discharge chamber. The internal pressure is adjusted to a vacuum value suitable for wafer processing.

  The processing gas is excited by the electric field and magnetic field supplied from the discharge unit 3 to form plasma in the discharge chamber. A metal disk-shaped member is disposed inside the sample stage 5 and is electrically connected to a high frequency power source that supplies power of a predetermined frequency. The sample is generated by the high frequency power supplied after the plasma is formed. A bias potential is formed above the upper surface of the wafer held by suction on the table 5, and charged particles in the plasma are attracted to the upper surface of the wafer due to the difference between this potential and the potential inside the plasma, and processing of the wafer is started.

  After the processing is detected and the plasma is extinguished and the adsorption of the wafer due to electrostatic force is released, a plurality of pins move upward from the inside of the sample table 5 to lift the wafer above the upper surface of the sample table 5. To separate. In this state, the gate valve opens the gate, and the transfer robot advances the arm tip into the lower part of the wafer in the processing chamber and places it on the upper surface to receive and hold it. Thereafter, the wafer is carried out of the processing chamber into the transfer chamber 4 by the arm contraction operation.

  Next, the configuration of the sample stage 5 will be described in detail with reference to FIG. FIG. 2 is an enlarged longitudinal sectional view showing the configuration of the sample stage of the embodiment shown in FIG. FIG. 3 is a cross-sectional view showing a cross section of the AA plane in FIG. 2.

  In FIG. 2, the sample stage 5 of the present embodiment is a disk-like member supported by the upper end portion of the support column that penetrates the inside of the through hole having an opening in the member constituting the bottom of the vacuum vessel 1. Yes, the lower surface of the center part of the disk is connected to and held by the upper end of the support column, and cables and pipes necessary for the success of the function of the sample table 5 are arranged inside the support column and connected to the sample table 5 Has been.

  The support column for supporting the sample stage 5 includes a cylindrical hollow shaft 6 having a cylindrical space inside and a shaft aligned with the central axis of the sample stage 5, and an inner side of the hollow shaft 6. And an insulating pipe 19 made of an insulating member. Also, a pusher pin hollow shaft 11 which is a cylindrical member disposed so as to surround the inside of the through hole and outside the outer wall of the hollow shaft 6 is disposed, and the upper end thereof will be described later. As shown, the pusher pins 13 that hold the wafer at the tip end thereof are connected to each other, and the lower end portions thereof are connected to the pusher pin linear guides 20.

  The hollow shaft 6 has an upper end connected to and fixed to the lower surface of the sample stage 5, and a lower end connected to a sample stage linear guide 21 constituted by an actuator or the like that moves the upper and lower directions. The sample table linear guide 21 of the present embodiment is an actuator that moves along guide means such as a rail disposed below the vacuum vessel 1 in the vertical direction. The actuator and the lower end of the hollow shaft 6 are connected by an arm. As a result, the hollow shaft 6 and the sample stage 5 connected thereto move in the vertical direction along the guide means. The pusher pin linear guide 20 is an actuator that moves along guide means such as a rail disposed vertically below the vacuum vessel 1. The arm, the pusher pin linear guide 20, and the lower end of the pusher pin hollow shaft 11 are driven by an arm. , The pusher pin hollow shaft 11 and the pusher pin 13 connected to the pusher pin 13 are moved in the vertical direction along the guide means.

  In this embodiment, the space between the pusher pin 13 and the pusher pin hollow shaft 11 is a ring-shaped member connected to the upper end portion of the pusher pin hollow shaft 11, and is connected to the upper end portion of the pusher pin hollow shaft 11. The pusher pin 13 is connected by a bellows flange 12 extending to a position on the outer peripheral side including the lower end portion. The bellows flange 12 has beam-like protrusions extending from the ring-shaped outer periphery to the outer peripheral side at three positions at equal angles in the circumferential direction from the center of the ring (the center of the pusher pin hollow shaft 11). And this protrusion part and the lower end part of the pusher pin 13 are connected.

  Further, on the outer side of the pusher pin hollow shaft 11, a bellows 7 is disposed so as to surround the pusher pin hollow shaft 11 and extend up and down in accordance with the vertical movement of the pusher pin hollow shaft 11. The upper end of the bellows 7 is airtightly connected to the lower surface of the bellows flange 12, and the lower end is connected to the inner wall surface of the vacuum vessel 1 constituting the processing chamber bottom surface with a ring-shaped member interposed therebetween. The ring-shaped member is an inner wall surface of the vacuum vessel 1 having a through hole, and is arranged so as to be in contact with the surface on the outer peripheral side of the opening on the processing chamber side of the through hole with the O-ring interposed therebetween, or the surfaces are opposed to each other. The ring-shaped member and the O-ring surround the through-hole while being attached in the vacuum vessel 1.

An O- ring 15 is disposed between the ring-shaped member at the lower end of the bellows 7 and the wall surface of the vacuum vessel 1 with which the bellows 7 is in contact. The O- ring 15 is fastened by any fastening means to generate a pressing force. A hermetic seal is realized by deformation (collapse) of the ring 15. Further, another bellows 7 is disposed between the upper surface of the bellows flange 12 and the lower surface of the sample table 5 positioned thereabove so as to surround the outer periphery of the upper end portion of the sample table hollow shaft 6. The other bellows 7 is hermetically connected to the upper surface of the bellows flange 12 at the lower end, and is fastened to the lower surface of the sample table 5 with the ring-shaped member and the O-ring 15 sandwiched between the upper bellows 7 at the upper end. Are connected and hermetically sealed inside and outside.

  With such a configuration, the inner space of the upper and lower bellows 7 is airtightly partitioned from the processing chamber inside the outer vacuum vessel 1 or a decompressed space communicating with the processing chamber, and a through hole in the lower portion of the vacuum vessel 1 The space inside the bellows 7 is maintained at a pressure (atmospheric pressure) equivalent to the outside pressure. That is, the space formed by these between the bellows 7 and the pusher pin hollow shaft 11 and the space 8 formed by these between the pusher pin hollow shaft 11 and the sample table hollow shaft 6 are defined in the vacuum vessel 1. The pressure is equal to the atmospheric pressure by communicating with the outer space. Furthermore, the cylindrical space 8 inside the sample stage hollow shaft 6 also has a space 8 which is communicated with the atmosphere and is set to a pressure equal to the atmospheric pressure.

  The sample stage 5 according to the present embodiment has a substantially cylindrical shape as a whole, and is a metal disk electrically connected to the RF bias power source 22 that supplies high-frequency power to form the above-described bias potential. A film made of a dielectric material is disposed on the upper surface of the circle to constitute a wafer mounting surface. In addition, a DC power source 23 that generates electrostatic force for adsorbing the wafer onto the dielectric film is electrically connected to the metal disk.

  Further, inside the metal disk, a refrigerant flow path 16 through which a refrigerant for adjusting the temperature of the disk and thus the sample stage 5 to a value within a desired range by heat exchange flows inside. Are arranged concentrically or spirally around the central axis of the disc. The refrigerant is supplied to the refrigerant flow path 16 through the refrigerant pipe 26 connected to the refrigerant temperature controller (not shown) arranged outside the vacuum vessel 1 and the refrigerant flow path of the sample stage 5 and circulates. A heater 27 that generates heat by supplying electric power is disposed between the coolant channel 16 and the dielectric film over the entire mounting surface of the upper surface of the disk, and the surface of the dielectric film or the upper surface of the disk. The calorific value is adjusted so that the temperature of the temperature becomes closer to a uniform temperature in the circumferential direction.

  The lower surface of the metal disk is connected to an insulating plate 18 made of a circular insulating material, and another metal disk is connected to the insulating plate 18 below the insulating plate 18. Thereby, the hollow shaft 6 for sample stands, the hollow shaft 11 for pusher pins, and a metal disc are electrically insulated. Furthermore, the sample stage 5 of the present embodiment is configured by integrally connecting the above-described configuration including the metal disk and the insulating plate 18, and the lower bellows 7, the sample stage hollow shaft 6, and the pusher pin hollow shaft 11. It is configured to be detachable.

  An RF feed shaft 10 for supplying bias power to a metal disk along the central axis of the sample table hollow shaft 6 is provided in the space 8 that is set to atmospheric pressure inside the sample table hollow shaft 6. A power supply cable 9 for supplying electric power to the heater 27 is disposed outside. Further, the RF feeding shaft 10 is in communication with an opening arranged at the center of the circular mounting surface of the sample stage 5 along the central axis, and a wafer is mounted on the mounting surface and processed. In this state, a He gas supply path through which a heat transfer (promotion) gas such as He supplied from the opening flows is arranged.

  The RF power supply shaft 10 is made of a conductive material, and the outer periphery thereof is covered with a hollow insulating pipe 19 made of an insulating material. The insulating pipe 19 and the insulating plate 18 insulate the RF power supply shaft 10 and the He gas supply path therein from the vacuum vessel 1, the bellows 7, the sample table hollow shaft 6, and the pusher pin hollow shaft 11 from the grounding location. ing.

  In the above embodiment, the sample stage 5 and the pusher pin 13 have linear guides that move each independently in the vertical direction. For this reason, the relative positions of the sample stage hollow shaft 6 and the pusher pin hollow shaft 11 are changed relative to each other along the central axis in the vertical direction which is arranged so as to match.

  In this embodiment, a ring-shaped guide bearing 14 is disposed between the outer wall surface of the sample table hollow shaft 6 and the pusher pin hollow shaft 11, and the outer wall surface of the sample table hollow shaft 6 and the inner wall surface of the pusher pin hollow shaft 11. And slide the guide bearing 14 to change the position up and down. That is, the vertical movement of the pusher pin 13 is performed by the pusher pin hollow shaft 11 with the guide bearing 14 sandwiched between the cylindrical inner side wall of the pusher pin hollow shaft 11 or the outer peripheral side wall surface of the sample stage hollow shaft 6. It is done by moving. In this embodiment, the guide bearing 14 is arranged to be fitted into the inner wall surface of the pusher pin hollow shaft 11 and moves up and down together with the pusher pin hollow shaft 11, but is fitted into the outer peripheral side wall of the sample table hollow shaft 6. The inner peripheral wall surface of the outer pusher pin hollow shaft 11 may slide and move with the guide bearing 14.

  For example, the sample table 5 is moved between the upper surface and the shower plate by changing the position of the upper surface (mounting surface) in the vertical direction in the processing chamber inside the vacuum vessel 1 by the operation of the linear guide 21 for the sample table. By changing the distance, the height of the discharge chamber is changed to one suitable for wafer processing by plasma. At this time, the pusher pin 13 is adjusted relative to the bottom surface of the vacuum vessel 1 (including not changing it) by driving the pusher pin linear guide 20 so that the entire state of the pusher pin 13 is maintained inside the sample stage 5. Is done. On the other hand, when the pusher pin 13 is moved up and down to lift the wafer above the mounting surface of the sample table 5 and move it away or move it downward to place it on the mounting surface, the position of the sample table 5 is moved. There is a case where only the relative position of the pusher pin 13 to the sample stage 5 (the mounting surface thereof) is changed without doing so. In each of these cases, the outer wall surface of the sample stage hollow shaft 6 and the inner wall surface of the pusher pin hollow shaft 11 slide on the guide bearing 14 and change their positions vertically.

  In such a configuration, the inner peripheral wall surface of the pusher pin hollow shaft 11 and the outer peripheral wall surface of the sample table hollow shaft 6 which are the guide surfaces in the above vertical movement are hermetically sealed from the processing chamber in the vacuum vessel 1 by the bellows 7. Exposure to the reaction product particles generated in the gas and plasma from the processing chamber is suppressed, and these sliding surfaces are contaminated by the deposits. Occurrence of obstacles that hinder vertical movement is reduced, and the operation reliability of the plasma processing apparatus is improved.

DESCRIPTION OF SYMBOLS 1 ... Vacuum container 2 ... Exhaust pump 3 ... Discharge part 4 ... Transfer chamber 5 ... Sample stand 6 ... Sample stand hollow shaft 7 ... Bellows 8 ... Space 9 ... Heater feed cable 10 ... RF feed shaft 11 ... Pusher pin hollow shaft 12 ... Bellows flange 13 ... Pusher pin 14 ... Bearing

Claims (3)

A processing chamber disposed inside the vacuum vessel and depressurized inside;
An exhaust pump for reducing the pressure by exhausting disposed processing chamber below the vacuum chamber,
Disposed in the processing chamber, comprising: a sample stage on which the wafer to be processed is mounted on the upper surface thereof, the
A plasma processing apparatus,
Arranged inside the sample stage, and a plurality of pins for supporting the wafer in spaced or the upper surface from the upper surface by moving the wafer in the vertical direction relative to the sample stage upper surface placed on the tip,
Are connected at the bottom and the center of the sample stage, a hollow shaft for supporting the sample stage in the processing chamber, a first shaft arranged through a through hole disposed in the vacuum container,
The said through hole at the outer peripheral side of the first axis is arranged as the first axis coaxial with a second axis of the hollow which is connected to the plurality of pins,
A bellows flange disposed on and connected to the outer periphery of the second shaft, and connected to the plurality of pins;
Between and between the underside and the inner wall surface of the vacuum vessel of the bellows flange and the upper surface of inside the bellows flange and the sample stage of the lower surface of the vacuum vessel, and the outer periphery of the second shaft and the through hole Two bellows that are placed around and extendable in the vertical direction,
Between the inner wall surface of the periphery of the through hole of the lower surface and the vacuum chamber upper and lower ends and of the sample stage of these bellows, said bellows being equal pressure and atmospheric pressure through the through hole Sealing means for hermetically sealing a space between the inside of the vacuum vessel and the inside of the vacuum container that has been decompressed ;
The plurality of pins arranged in the vertical direction between the outer wall surface of the first shaft and the inner wall surface of the second shaft, and the second shaft and the plurality of pins connected to the second shaft with respect to the first shaft. A plasma processing apparatus comprising a guide bearing that is slidably movable in the vertical direction. 2. The plasma processing apparatus according to claim 1, wherein a cable for supplying high-frequency power to the sample stage or an upper surface of the sample stage is disposed inside the first shaft having a pressure equal to atmospheric pressure. A plasma processing apparatus in which a supply path of gas supplied from an opening is arranged.   3. The plasma processing apparatus according to claim 1, wherein the vertical position of the sample stage can be changed in the processing chamber by moving the first axis in the vertical direction.

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