JP2010199461A - Plasma treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide plasma treatment apparatus enhancing the reliability by suppressing the generation of a foreign matter. <P>SOLUTION: This plasma treatment apparatus treats a sample placed on a sample support positioned in a treating chamber in the inside of a vacuum container using a plasma formed in the treating chamber, and includes a space for exhaustion which communicates in a horizontal direction with the treating chamber and allows a gas in the treating chamber to pass, an exhaust outlet which communicates with the space through which the exhausted gas is discharged, a pump positioned so as to communicate with the exhaust outlet for exhausting the gas, and a plate member positioned between a junction with the treating chamber and the exhaust outlet in the inside of the space for exhaustion and extended along a direction connecting the junction with the treating chamber with the exhaust outlet, wherein the plate member is positioned out of the potential angle from the top face of the sample support. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus for processing a substrate-like sample such as a semiconductor wafer in a processing chamber inside a vacuum vessel using plasma formed in the processing chamber, and in particular, fine particles flying from a vacuum pump side to an object to be processed. Is to reduce foreign matter on the object to be processed.

  In the plasma processing apparatus as described above, generally, a sample is processed in a reduced-pressure vacuum atmosphere. In such a processing apparatus, it is necessary to lower the pressure in the processing chamber to a high degree of vacuum at the time of processing, and in order to realize this, a vacuum pump having a plurality of blades rotating around the same axis, such as a turbo molecular pump Is generally used.

  On the other hand, reaction products generated in the plasma processing of the sample in the processing chamber and fine particles sputtered by the plasma adhere to and deposit on the wall surface in the processing chamber. When such a sample is processed for a long time or for a large number of samples, adhesion accumulated on the surface of the processing chamber, deposits may change in the pressure in the processing chamber, change in the temperature of the surface, and mutual interaction with plasma. Fine particles are generated due to separation or defects due to action or the like.

  Part of the fine particles generated in this way is transferred to the vacuum pump and discharged out of the processing chamber, but the other part adheres to the surface of the sample and becomes a foreign substance. In addition, since the impeller is rotating at high speed around the axis, the fine particles that have reached the vacuum pump fly into the inside from the opening of the inlet of the vacuum pump, collide with the impeller, and jump to the processing chamber side. It is known that the particles are scattered in the processing chamber and adhere to the upper surface of the sample to become foreign matter (hereinafter referred to as recoil foreign matter). Such an example is disclosed in, for example, Nippon Kogyo Publishing Clean Technology, June 2003, page 20, visualization of backflow particles from a turbo molecular pump, Shintaro Sato (Non-patent Document 1).

  A technique disclosed in Japanese Patent Application Laid-Open No. 2007-170467 (Patent Document 1) is known as a technique for suppressing such an adverse effect caused by the recoil foreign matter. In this conventional technique, a disk-shaped fine particle reflecting member is provided in the exhaust manifold so as to face the turbo molecular pump to solve the problem of the recoil foreign matter.

JP 2007-180467 A

Clean Technology, June 2003, 20p, Nihon Kogyo Publishing

  When the processing is repeated in the processing chamber of the plasma processing apparatus, the above-described fine particles gradually accumulate on the wall surface in the processing chamber, and the possibility of dropping or peeling off increases. As a result, the number of suspended fine particles increases, and more particles adhere to the sample and become foreign matters. Further, the fine particles floating in the plasma or in a simple gas flow where no plasma is generated are exhausted to the turbo molecular pump along the gas flow of the vacuum exhaust, and most of the fine particles are discharged outside the apparatus. However, some of the fine particles collide with the impeller rotating at high speed of the turbo molecular pump and are blown off. Some of the fine particles bounced off (referred to as recoil microparticles) collide with other members and are exhausted again, but some rebound to the sample and become foreign matter.

  In the above-mentioned prior art, since the following points are not fully considered, there is a problem.

  That is, in the reflection member facing the turbo molecular pump as in Patent Document 1, the gas flow is hindered, so that fine particles from the wafer side are likely to be deposited and become a new foreign matter generation source. Further, since the vacuum exhaust efficiency is lowered, the etching performance is affected.

  That is, even if the reflection member reduces the recoil foreign matter to the sample in the processing chamber, the deposit or recoil foreign matter accumulates on the reflection member. There is a risk of becoming a new source of foreign matter. In order to suppress this, maintenance work such as periodic cleaning and replacement of the reflecting member is necessary, and during this work, it is necessary to stop the processing of the sample by the processing apparatus and release it to the atmosphere. The operating rate of the processing apparatus and the processing efficiency are reduced.

  Furthermore, when considering the efficiency of exhaust by the turbo molecular pump, the reflecting member acts as a resistor provided on the exhaust path, thus reducing the fluctuation of the gas exhaust flow and the effective exhaust speed. As a result, the processing efficiency may be impaired. In the above-described prior art, such a point has not been fully considered and a problem has occurred.

  An object of the present invention is to provide a plasma processing apparatus that improves the reliability by suppressing the generation of foreign substances.

  An object of the present invention is a plasma processing apparatus for processing a sample placed on a sample stage disposed in a processing chamber inside a vacuum vessel using plasma formed in the processing chamber. An exhaust space connected in the direction through which the gas in the processing chamber passes, an exhaust port communicating with the space from which the exhausted gas is exhausted, and communicating with the exhaust port for exhausting the gas A plate member disposed between the exhaust port and a connection portion between the pumping chamber and the processing chamber, and extending along a direction connecting the two, and the upper surface of the sample table This is achieved by a plasma processing apparatus provided with a plate member disposed outside the expected angle from the above.

  An exhaust duct that is connected to the processing chamber in a horizontal direction and is exhausted through the gas in the processing chamber, an exhaust port that communicates with the space and exhausts the exhausted gas, and an exhaust A pump disposed in communication with the port for exhausting the gas, and a gas flow in the exhaust duct disposed between the exhaust port and a connection portion between the processing chamber and the exhaust port. This is achieved by including a plate member extending along the plate member disposed outside the prospective angle from the upper surface of the sample stage.

  Furthermore, the space in which the plasma is formed in the processing chamber has a cylindrical shape, the sample stage has a cylindrical shape and is disposed coaxially with the space in which the plasma is formed, and the exhaust space is the sample. A planar shape extending in the horizontal direction from the opening of the connecting portion arranged below the base is a polygonal space, and the exhaust port is arranged at a distance from the opening in the horizontal direction on the bottom surface of the space Is achieved.

  Furthermore, this is achieved by the tip of the plate member on the processing chamber side being located closer to the exhaust port than the connection portion.

It is a longitudinal cross-sectional view which shows the outline of a structure of the process chamber of the plasma processing apparatus which concerns on the Example of this invention. It is a longitudinal cross-sectional view which shows the outline of a structure of the exhaust duct vicinity of the Example shown in FIG.

  An embodiment of the present invention will be described below with reference to the drawings.

  Embodiments of the present invention will be described below with reference to FIGS.

  FIG. 1 is a longitudinal sectional view showing an outline of a configuration of a processing chamber of a plasma processing apparatus according to an embodiment of the present invention. FIG. 2 is a longitudinal sectional view showing an outline of the configuration in the vicinity of the exhaust duct of the embodiment shown in FIG.

  In these drawings, a plasma processing apparatus 1 is connected to a vacuum vessel in which a processing chamber for processing a sample is arranged, and discharge means arranged to surround the outside of the vacuum vessel and a lower portion of the vacuum vessel. And an exhaust means for exhausting the inside of the processing chamber. The discharge means includes an electric field supply device and a magnetic field supply device which are arranged on the outer peripheral side of the upper portion of the processing vessel 2 which is a cylindrical portion of the vacuum vessel and arranged so as to cover this. Further, the vacuum container is configured to include an exhaust duct 29 that communicates with the processing chamber inside the processing container 2 and is connected to the processing container 2 in the horizontal direction.

  As described above, the processing container 2 is a container constituted by a cylindrical part of a vacuum container, and the inside of the processing chamber 19 having a cylindrical shape and the inside of the processing chamber 19 are arranged coaxially therewith. And a cylindrical sample stage 4. Further, the side wall of the processing container 2 is provided at the same height as the upper surface of the sample table 4 and includes an opening (gate) through which the sample is loaded and unloaded. A gate valve 22 that opens and seals the gate hermetically is disposed outside the side wall.

  In addition, above the processing chamber 2 and above the processing chamber 19, a shower plate 6 having a plurality of holes formed in a disk shape constituting the ceiling is provided on the upper surface of the dielectric disk. A small gap is provided between the lid member 5 and the lid member 5. The gap and the gas supply pipe communicate with each other, a processing gas for processing the sample is supplied into the gap, diffuses into the gap, and is disposed in the central portion of the shower plate 6. A processing gas is introduced into the processing chamber 19 from the gap through the through hole.

  Above the processing vessel 2, the shower plate 6 and the disc-like lid member 5 made of a dielectric, and a cylindrical lid member 8 that is disposed above and constitutes a vacuum vessel are further disposed. Inside the lid member 8, an antenna 7 made of a disk-like conductor is connected to the radio wave source 11 and supplied with high-frequency power to supply an electric field to the inside of the processing chamber 19. And a dielectric 12 having a ring shape that is disposed between the cover member 8 and the cover member 8. A solenoid coil 9, which is a magnetic field generator arranged so as to surround the lid member 8 and the side wall of the processing container 2 around the side of the processing container 2, is disposed on the outer peripheral side of the processing container. A magnetic field is supplied inside.

  The exhaust duct 29 is connected to the cylindrical portion of the processing container 2 and communicates with the internal processing chamber 19. In the present embodiment, the exhaust duct 29 has a shape that can be regarded as a polyhedron that is formed of a flat plate having a polygonal shape and a side wall extending in the vertical direction.

  The interior is a space that is a flow path through which particles such as gas and products inside the processing chamber 19 flow from the processing chamber 19 and are discharged from the exhaust port 30 on the bottom surface. The space that is the flow path extends in the horizontal direction with respect to the vertical axis of the cylindrical portion of the processing chamber 19, and the processing chamber 19 is connected to the processing chamber 19 at an opening 31 that is a connection portion with the processing chamber 19. It is communicated. The exhaust passage of the exhaust duct 29 extends from the opening 31 to above the exhaust port 30 and extends in a direction connecting these (centers thereof). The gas in the processing chamber 19 flows from the opening 31 and moves in the horizontal direction, and then flows into the turbo molecular pump 14 disposed at a distance in the horizontal direction with respect to the axis of the processing chamber 19. Discharged outside. At the bottom of the exhaust duct 29 above the inlet of the turbo molecular pump 14 and at a distance from the processing vessel 2 in the horizontal direction, a circular shape through which the gas and particles inside the processing chamber 19 communicate with the inlet. The exhaust port 30 is arranged.

  A circular lid 16 for opening and closing the exhaust port 30 is disposed above the exhaust port 30 and connected to the upper part of the exhaust duct 29 together with the driving means. In addition, an exhaust passage is formed between the lower part of the exhaust port 30 and the inlet of the turbo molecular pump 14, and the passage area of the exhaust passage is variable by rotating around a horizontal axis on the passage. A plurality of variable valves 15 to be adjusted are arranged. Further, on the downstream side of the turbo molecular pump 14, a dry pump 21 that is connected to the turbo molecular pump 14 as a flow path and roughens the processing chamber 19 to a pressure at which the turbo molecular pump 14 can operate is disposed. With these configurations, even when a sample is processed while a processing gas is supplied from the through hole of the shower plate 6 and a product is formed by plasma, a high vacuum can be maintained in the processing chamber 19. It has become. In the present embodiment, the exhaust port 30, the turbo molecular pump 14 and the exhaust flow passage connecting them have a circular cross section and their axes are coaxial.

  The pressure in the processing chamber 19 is detected by a pressure gauge 23 provided at the lower part of the processing container 2. The pressure gauge 23 is communicably connected to the control device 20 that adjusts the operation of the high-frequency power source 13 that supplies high-frequency power to the electrode made of a conductor in the sample stage 4, the radio wave source 11, the mass flow controller 10, and the like. An output signal indicating the pressure is transmitted from the pressure gauge 23 to the control device 20, and the control device 20 controls the variable valve 15 or the turbo molecular pump 14 and the processing gas based on the pressure value detected by this signal. By sending signals for adjusting the operation such as supply to these, the processing conditions of the sample including the pressure are adjusted even during the processing.

  Furthermore, in this embodiment, a plurality of plate-like reflecting members 17 that are arranged in parallel in the vertical direction and extend in the horizontal direction are arranged inside the exhaust flow path of the exhaust duct 29. In particular, these reflecting members 17 are located in the exhaust duct 29 and between the opening 31 and the exhaust port 30, and constitute the outer peripheral end of the upper surface of the sample table 4 (in particular, the upper surface of the sample table 4). A plurality of sheets are installed in parallel along the moving direction (flow direction) of the exhaust gas outside the prospective angle 18 through the opening 30 from the outer peripheral edge of the sample 3 such as a semiconductor wafer placed on the sample mounting surface). ing. Operations related to these reflecting members 17 will be described later.

  The operation of the plasma processing apparatus 1 having the above configuration will be described below. First, when processing the sample 3, a processing container designated by the control device 20 based on a command from a host control device that controls the manufacture of a semiconductor device in a building such as a clean room where a plasma processing device 1 (not shown) is arranged. The second gate valve 22 is opened, and the sample 3 is loaded and placed above the sample stage 4 in the decompressed processing chamber 19.

  When the sample 3 is adsorbed and held on the upper surface of the sample table 4 by an electrostatic adsorption device (not shown), a heat transfer gas such as He is introduced between the sample 3 and the sample mounting surface. Next, the processing gas whose flow rate is adjusted by the mass flow controller 10 passes through the gap between the lid member 5 and the shower plate 6, is supplied to the processing chamber 19 through a plurality of holes formed in the shower plate 6, and is supplied to the antenna 7. The electric field emitted from the antenna 7 by the generated electric power is introduced into the processing chamber 19 through the lid member 5 and the shower plate 6, and the magnetic field generated by the solenoid coil 9 is supplied into the processing chamber 19. By these interactions, the processing gas substance is excited and plasma is formed in the space inside the processing chamber 19 above the sample 3.

  Furthermore, the charged potential in the plasma is attracted in the direction of the sample 3 by the bias potential formed above the sample 3 by the electric power supplied from the high frequency power supply 13 to the electrode in the sample table 4, and the etching process of the sample 3 is started. Is done. When it is determined by a film thickness or processing depth determination device using light emission (not shown) that the etching has progressed to a predetermined time or a predetermined depth, the high frequency power supply 13 is based on a command from the control device 20. Stopped. Next, the processing gas is stopped, the conductance of the variable valve 15 is maximized (the valve opening is set to 100%), and excess gas in the processing chamber 19 is exhausted.

  Thereafter, electrostatic adsorption of the sample 3 is removed, the gate valve 22 is opened, and the sample 3 is carried out. Thereafter, a new sample 3 is again introduced and the same process is repeated.

  When such a process is repeated, the fine particles gradually accumulate on the wall surface of the processing chamber 19, and the possibility of dropping or peeling off increases. As a result, the number of suspended fine particles increases, and more particles adhere to the sample and become foreign matters. Further, fine particles floating in the plasma or in a simple gas flow in which no plasma is generated are exhausted to the turbo molecular pump 14 along with the gas flow of vacuum exhaust, and most of the fine particles are discharged outside the apparatus. However, some of the fine particles collide with the blades of the impeller 27 that rotates at high speed around the rotation shaft 28 inside the turbo molecular pump 14 and are blown off. Some of the fine particles bounced off (referred to as recoil microparticles) collide with other members and are exhausted again, but some rebound to the sample and become foreign matter.

  In FIG. 1 and FIG. 2, the locus 24 of recoil particles is shown by a broken line as an example. Whether or not the recoil particles reach the sample 3 depends on the internal shape of the plasma processing apparatus from the turbo molecular pump 14 to the sample. As a whole, the gas flow in the vacuum vessel is generated between the space (upstream side) in the processing chamber 19 above the sample 3 and the exhaust port 30 above the turbo molecular pump 14 in the exhaust duct 29. The flow (movement) of the particles increases the fluid force acting on the internal particles as the pressure in the processing chamber 19 increases and the flow rate increases, so that foreign particles caused by the recoil particles that are blown off by the turbo molecular pump 14 are generated. It can be said that it is desirable to treat the sample 3 with a pressure and a flow rate that can be reduced. However, depending on the processing conditions, realizing such conditions may impair processing efficiency. In a plasma processing apparatus in which processing may be performed under such conditions, it is necessary to suppress the recoil particles from reaching the sample 3 and becoming foreign matter.

  The present embodiment has a configuration that reduces recoil particles in the exhaust duct 29 on the upstream side of the turbo-molecular pump 14 and moves to the inside of the processing chamber 19 to become foreign matter. ing. That is, a plurality of plate-like reflecting members 17 that are located in the exhaust duct 29 and located between the opening 31 and the exhaust port 30 and are arranged in parallel in the vertical direction and extending in the horizontal direction are arranged.

  These reflecting members 17 are arranged so that at least a part thereof exists in the prospective angle 32 to the inside of the processing chamber 19 through the opening 31 of the exhaust port 30. This is because the recoiled fine particles bounced off are scattered linearly through the exhaust port 30, and this is blocked on the scattering trajectory, and the processing chamber 19 enters the exhaust port 30 via the opening 31 and the reflecting member 17. This is to reduce the exposed area.

  In particular, in this embodiment, a cover made of a dielectric material such as quartz is disposed on the upper surface of the sample table 4 or on the outer periphery of the upper side wall, and interaction with particles in the plasma or reactive substances in the processing gas. The inside of the sample stage 4 is protected from the above. This cover faces or is close to the plasma formed above the sample stage 4 and becomes high temperature. Even if particles such as products in the plasma adhere, they are likely to be dissociated or released. The reflecting member 17 of this embodiment is disposed so that the cover is not exposed to the exhaust port 30 through the opening 31 and the reflecting member 17. That is, the plurality of reflecting members 17 shield the exhaust port 30 from the cover, and recoil particles flying from the exhaust port 30 adhere to the cover, dissociate again, float on the upper portion of the processing chamber 19, and foreign matter in the sample 3. Is suppressed.

  On the other hand, it is considered that the reflecting member 17 is installed inside the prospective angle 18 from the upper surface of the sample table 3. In this case, the tip of the reflecting member 17 protrudes into the processing chamber 19, and the gas flow is inhibited in the processing chamber 19. This further makes it easy for products and particles in the exhaust gas to adhere to the reflecting member 17. Further, in such an arrangement, the particles in the gas in the exhaust duct including the exhaust port 30 and the particles and slices released from the deposits attached to the wall surface, reflected from the turbo molecular pump 14 and the variable valve 15 and rebounded. Some of the particles adhere to the reflecting member 17, and the adhered and accumulated products and particles are directly exposed to the upper surface of the sample table 4 in the processing chamber 19, and new foreign substances are present. It becomes a source.

  In the present embodiment, the reflecting member 17 is disposed on the upper surface of the sample table 4, particularly, on the outer peripheral end of the upper surface of the sample table 4, outside the prospective angle 18. It does not protrude. Further, the exhaust duct 29 is arranged in parallel to the direction of exhaust, and the flow of exhaust in the exhaust duct 29 is prevented from being obstructed by the reflecting member 17. With such a configuration, occurrence of foreign matters from the reflecting member 17 is reduced. Further, the recoil particles from the turbo molecular pump 14 or the variable valve 15 and the exhaust port 30 collide with the reflecting member 17 to consume kinetic energy and to suppress the acquisition of new kinetic energy. For this reason, even if it recoils, the speed is reduced below the incident speed, so that it is difficult to fly to the sample 3 in the exhaust gas, and the recoil foreign matter bounced off by the means and configuration for exhaust gas is reduced.

  In the plasma processing apparatus 1 as described above, for maintenance such as cleaning and inspection inside the processing chamber 19, the vacuum vessel is periodically opened to the atmosphere and the parts are replaced and the exhaust duct is cleaned. Is called. The reflecting member 17 may be configured to be removable, and may be configured to be replaced with a cleaned or new reflecting member 17. By adopting such a configuration, the exhaust path is bent, so that the efficiency of maintenance work of the reflecting member 17 disposed inside the exhaust duct 29 is improved and the operating efficiency of the apparatus is improved. These parts may be made of metal, but they may be made of quartz or ceramics that have no fear of metal contamination since the structure is simple. In this case, cleaning with an acid is possible, so that there is an effect that the cleaning can be sufficiently performed.

  As described above, according to the present embodiment, the exhaust duct 29 is configured to shield and suppress the recoil particles from the turbo molecular pump 14 side, the recoil foreign matter is suppressed, and the exhaust efficiency or maintenance work is performed. Improves.

DESCRIPTION OF SYMBOLS 1 Plasma processing apparatus 2 Processing container 3 Sample 4 Sample stand 5,8 Cover member 6 Shower plate 7 Antenna 9 Solenoid coil 10 Mass flow controller 11 Radio wave source 12 Dielectric 13 High frequency power supply 14 Turbo molecular pump 15 Variable valve 16 Cover 17 Reflecting member 18 Expected angle 19 Processing chamber 20 Control device 21 Dry pump 22 Gate valve 23 Pressure gauge 24 Trajectory of recoil particulate 25 Net 26 Fixed blade 27 Impeller 28 Rotating shaft 29 Exhaust duct 30 Exhaust port 31 Opening

Claims (5)

A plasma processing apparatus for processing a sample placed on a sample stage disposed in a processing chamber inside a vacuum vessel using plasma formed in the processing chamber,
An exhaust space that is connected to the processing chamber in a horizontal direction and through which gas in the processing chamber passes, an exhaust port that communicates with the space and exhausts the exhausted gas, and communicates with the exhaust port. A pump disposed and exhausting the gas; and a plate member disposed between the connection portion with the processing chamber and the exhaust port in the exhaust space and extending in a direction connecting the two A plasma processing apparatus comprising: a plate member disposed outside a prospective angle from the upper surface of the sample stage. A plasma processing apparatus for processing a sample placed on a sample stage disposed in a processing chamber inside a vacuum vessel using plasma formed in the processing chamber,
An exhaust duct that is connected to the processing chamber in a horizontal direction and is exhausted through the gas in the processing chamber, an exhaust port that communicates with the space and exhausts the exhausted gas, and an exhaust port. A pump arranged in communication and exhausting the gas, and along the flow of gas in the exhaust duct disposed between the exhaust port and a connection portion with the processing chamber inside the exhaust duct. A plasma processing apparatus comprising: an extending plate member, and a plate member disposed outside a prospective angle from the upper surface of the sample stage. The plasma processing apparatus according to claim 1,
A space in which the plasma is formed in the processing chamber is cylindrical, the sample stage has a cylindrical shape and is arranged coaxially with the space in which the plasma is formed, and the exhaust space is below the sample stage. The planar shape extending in the horizontal direction from the opening of the connecting portion disposed in the space is a polygonal space, and the exhaust port is disposed on the bottom surface of the space at a distance in the horizontal direction from the opening. Processing equipment. The plasma processing apparatus according to claim 2,
A space in which the plasma is formed in the processing chamber has a cylindrical shape, the sample stage has a cylindrical shape and is disposed coaxially with the space in which the plasma is formed, and the exhaust duct is disposed below the sample stage. A plasma processing apparatus, which is a space extending in a horizontal direction from the opening of the connecting portion, wherein the exhaust port is disposed at a bottom surface of the space at a distance in the horizontal direction from the opening. The plasma processing apparatus according to any one of claims 1 to 4,
A plasma processing apparatus, wherein a front end of the plate member on the processing chamber side is located closer to the exhaust port than the connection portion.

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