JP2009176991A - Plasma processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma processing device to process the circumferential part of a wafer using a microwave discharge plasma. <P>SOLUTION: A discharge tube 7 is provided at an opening of a waveguide. A slit 8 is formed at a part exposing outward from the waveguide of the discharge tube. A block 9 surrounding the discharge tube is attached to the waveguide. The block has a plasma generating chamber 10 and a first passage 11 and a second passage 12. The discharge tube is accommodated in an opening of the first passage; and an opening of the second passage makes a wafer insertion port 12a. The block has a gas supply piping 13 and a gas exhaust piping 14. A turn table 17 is disposed in front of the block. A covering plate 28 to cover the wafer 16 put on the turn table and an actuator 23 to move up and down the covering plate are provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus for irradiating a peripheral portion of a disk-shaped workpiece with microwave discharge plasma and plasma-treating the peripheral portion, and in particular, irradiating the peripheral portion of a wafer with microwave discharge plasma, The present invention relates to a plasma processing apparatus for removing excess coating and particles remaining on the peripheral edge.

  In the semiconductor device manufacturing process, prior to the etching process, the surface of the wafer is coated with a film such as a photoresist, and the coating of the portion to be etched on the wafer surface is removed to expose the lower layer. Thereafter, in an etching process, the wafer is placed on a stage in a plasma processing chamber, and an exposed region of the wafer surface is etched by the generated plasma.

  During this etching process, by-products (for example, polymers composed of carbon, oxygen, nitrogen, fluorine, etc.) generated by etching are likely to collect on both the front and back surfaces of the peripheral edge of the wafer. In this case, the plasma used for etching hardly reaches the peripheral portion of the wafer, and as a result, these by-products are deposited on both the front and back surfaces of the peripheral portion of the wafer and remain as particles. In addition, the excess coating film remains on the peripheral edge of the wafer without being removed.

  However, if the coating film or deposited particles are left on the peripheral edge of the wafer, it may cause serious damage to the semiconductor device in the subsequent processes. Therefore, these must be surely removed. .

  For this reason, there has been proposed an apparatus for removing excess coating or particles from the peripheral edge of the wafer. For example, a cathode is provided so as to apply a high frequency to the wafer through a stage disposed inside the chamber, a ring-shaped lower anode is provided at a position lower than the periphery of the wafer at the outer periphery of the stage, and a ring is provided above the stage. An upper anode in the shape of a ring is arranged so as to face the lower anode in the shape of a ring, and a discharge is simultaneously performed between the peripheral edge of the wafer and the upper anode in the shape of a ring and between the peripheral edge of the wafer and the lower anode in the shape of a ring. There is known an apparatus configured to continuously etch a region extending from the top surface to the bottom surface of a wafer periphery using generated plasma (see Patent Document 1).

  Further, the plasma processing chamber includes a plasma processing chamber, a wafer support that is disposed in the plasma processing chamber and on which the wafer is placed, and a gas distribution plate that is disposed so as to face the wafer support. Surrounded by a lower edge electrode that is electrically insulated by a side dielectric ring, the gas distribution plate is surrounded by an upper edge electrode that is electrically insulated by an upper dielectric ring, and the upper edge electrode has an RF An apparatus is known in which a power supply is connected, a lower edge electrode is grounded, and plasma processing is performed on the peripheral edge of the wafer by plasma generated between the upper and lower edge electrodes (see Patent Document 2). .

  Since these conventional apparatuses use capacitively coupled plasma that generates plasma using an RF electric field generated between electrodes, a low pressure atmosphere of 1 Torr or less is required. Therefore, in order to maintain the inside of the plasma processing chamber (chamber) in a low pressure state, an expensive and large-sized vacuum evacuation device or the like is required. There was a problem.

  On the other hand, the microwave discharge plasma can be stably generated even in the atmospheric pressure. Therefore, if plasma treatment is performed using this, an expensive and large-sized vacuum exhaust device or the like is not necessary. However, in the prior art, there has been no apparatus capable of processing the peripheral portion of the wafer using the microwave discharge plasma.

Republished Patent No. WO2004 / 100247 International Publication No. WO2007 / 038580 Pamphlet

  Therefore, the subject of this invention is providing the plasma processing apparatus which processes the peripheral part of a wafer using a microwave discharge plasma.

  In order to solve the above-described problems, the present invention is a plasma processing apparatus for irradiating a peripheral portion of a disk-shaped workpiece with microwave discharge plasma and plasma-treating the peripheral portion, and the microwave is introduced. A waveguide having a flat rectangular cross section, a microwave generation source, and a microwave supply path for supplying microwaves from the microwave generation source to the waveguide, and one side wall of the waveguide Has a longitudinally elongated opening along the microwave propagation direction, and further includes a dielectric discharge tube attached to the waveguide and extending along the opening. A vertically long slit is formed along the opening in the wall portion not facing the waveguide, and the block is attached to a side wall of the waveguide having the discharge tube and surrounds the discharge tube. The block comprises A plasma generation chamber formed inside the block and extending along the discharge tube, a first surface facing the side wall of the waveguide, and a second surface located on the opposite side of the first surface A first passage having a slot-like cross section that extends from the plasma generation chamber to the inside of the block and opens to the first surface, and extends from the plasma generation chamber to the inside of the block to the second surface. A second passage having a slot-shaped cross section that opens, and the discharge tube is accommodated in the opening of the first passage, and the opening of the second passage forms a workpiece insertion port, The block further includes a gas supply line for supplying gas to the plasma generation chamber, and a gas discharge line for discharging gas from the plasma generation chamber, and further includes a reactive gas supply source and the reactive gas Supply source and gas supply A reaction gas supply pipe for connecting a path, a circular turntable disposed in front of the workpiece insertion port of the block, and the workpiece to be placed thereon, and protruding from the back surface of the turntable A motor connected to a rotating shaft, a covering plate that covers the object to be processed placed on the turntable, and the covering plate is moved up and down so that the object to be processed has a gap therebetween. And a covering plate moving mechanism that takes a closed position away from the object to be processed and an open position away from the object to be processed.

  In the above configuration, preferably, a portion of the waveguide to which the block is attached is curved so that the second surface of the block is inside, and is a surface perpendicular to the rotation axis of the turntable. In the upward projection, the plasma generation chambers of the waveguide, the discharge tube, and the block are respectively located on the circumference of a concentric circle centered on the center of the turntable, while the second of the block The surface is curved with a smaller curvature than the workpiece.

  Preferably, the workpiece is transported to the turntable and a part of the workpiece is inserted into the workpiece insertion port, and at the same time, the center of the workpiece coincides with the center of the turntable. As described above, by placing the object to be processed on the turntable, the peripheral part of the object to be processed is introduced into the plasma generation chamber, and then the object to be processed is unloaded from the turntable. Is provided.

The coating plate is provided with a plurality of gas inlets for introducing an inert gas into the gap between the coating plate and the object to be processed when the coating plate is in the closed position. And an inert gas supply source, and an inert gas supply pipe connecting the inert gas supply source and the gas inlet.
It is also preferable that an object detection sensor for positioning the object to be processed is arranged on each side of the block in the longitudinal direction of the object insertion port.

Preferably, the discharge tube is provided on an H surface of the waveguide.
Further, a magnet for a mirror magnetic field trap is provided in the vicinity of the workpiece insertion port in the block, or the plasma generation chamber is in the vicinity of the gas supply line in the block. It is preferable that a heater for heating the reaction gas supplied to is incorporated.

Moreover, it is preferable that a cooling water circulation path is provided in the vicinity of the discharge tube inside the block.
The housing further includes a housing for shielding from outside air, and the turntable and the covering plate are accommodated in the housing, and the second surface of the block is disposed outside the housing. The block is attached so as to face the outer wall surface of the housing, and an opening with a shutter for carrying the object to be processed into the housing is provided on the wall surface of the housing facing the wall surface to which the block is attached. Is preferably provided.

  According to the present invention, since the peripheral portion of the circular workpiece is subjected to plasma processing using microwave discharge plasma, plasma processing can be stably performed in a pressure range of atmospheric pressure to 20 mTorr. Therefore, an expensive and large vacuum evacuation device is not required, the structure of the device can be simplified, and the manufacturing cost and operating cost of the device can be suppressed.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view showing a configuration of a main part of a plasma processing apparatus according to one embodiment of the present invention, FIG. 2 is a diagram showing a configuration of a discharge tube, and (A) is a perspective view, (B) is a plan view, and (C) is a cross-sectional view. 3 is a perspective view of a waveguide having a discharge tube mounted thereon, FIG. 4 is a plan view of the plasma processing apparatus according to the present invention, and FIG. 5 is a cross-sectional view of the plasma processing apparatus according to the present invention. It is.

In this embodiment, the present invention is configured as a plasma processing apparatus for irradiating a peripheral portion of a wafer with microwave discharge plasma to remove excess coating and particles remaining on the peripheral portion.
Referring to FIG. 1, according to the present invention, a flat rectangular cross-section waveguide 1 into which a microwave is introduced, a microwave generation source (microwave power source) 2, and a microwave generation source 2 are used. A microwave supply path 3 for supplying microwaves to the wave tube 1 is provided. An isolator 4 and a microwave matching unit 5 are disposed in the microwave supply path 3. A short circuit plunger 6 is connected to the end of the waveguide 1 opposite to the microwave supply path 3.

A longitudinally long opening 1b is formed in the side wall forming the H surface of the waveguide 1 along the propagation direction of the microwave, and a discharge tube 7 extending along the opening 1b is attached to the opening 1b. The discharge tube 7 is formed of a dielectric material such as quartz, alumina, yttria, and sapphire, and a longitudinal slit 8 is formed along the opening in a wall portion of the discharge tube 7 that does not face the waveguide 1. In this embodiment, as shown in FIG. 2, the discharge tube 7 is composed of an elongated main body 7a having a U-shaped cross section and closed at both ends, and a flange 7b provided at an opening edge of the main body 7a. ing. As shown in FIG. 3, the discharge tube 7 is attached to the waveguide 1 such that the main body 7 a is fitted into the opening of the waveguide 1 and the flange 7 b is in contact with the outer wall surface of the waveguide 1. The
In this embodiment, the discharge tube 7 is attached to the opening of the waveguide 1 in such a manner that a part of its wall penetrates into the inside of the waveguide 7. The discharge tube 7 may be attached to the opening 1b of the waveguide 1 in an arrangement so as to be close to the opening 1b on the outside.

  As shown in FIG. 1, a block 9 surrounding the discharge tube 7 is attached to the side wall (H surface) of the waveguide 1 including the discharge tube 7. 4 and 5, the block 9 is fixed to the discharge tube 1 with a screw 20 via a seal member 19 between the block 9 and the flange 7 b of the discharge tube 7. Inside the block 9, a plasma generation chamber 10 extending along the discharge tube 7 is formed. The block 9 extends from the plasma generation chamber 10 to the inside of the block 9 with a first surface 9a facing the side wall of the waveguide 1 and a second surface 9b located on the opposite side of the first surface 9a. The first passage 11 has a slot-like cross section that opens to the first surface 9a, and the second passage 12 has a slot-like cross section that extends from the plasma generation chamber 10 to the inside of the block 9 and opens to the second surface 9b. is doing. The discharge tube 7 is accommodated in the opening of the first passage 11 and the opening of the second passage 12 forms a wafer insertion port 12a.

The block 9 further has a gas supply line 13 for supplying gas to the plasma generation chamber 10 and a gas discharge line 14 for discharging gas from the plasma generation chamber 10. Each of the gas supply pipe 13 and the gas discharge pipe 14 is composed of a plurality of pipe groups arranged at intervals in the longitudinal direction of the plasma generation chamber 10, and the pipe groups are arranged on the way. It has the buffer part 13a and 14a extended in the vertical direction which communicates.
Further, the gas supply line 13 is connected to a reaction gas supply source (not shown) through the reaction gas supply pipe 15.

  In addition, a mirror magnetic field trap magnet 27 is provided in the vicinity of the wafer insertion opening 12 a in the block 9, and a reaction supplied to the plasma generation chamber 10 in the vicinity of the gas supply pipe 13 in the block 9. A heater 25 for heating the gas is incorporated. Furthermore, a cooling water circulation path 26 for cooling the discharge tube 7 when plasma is generated is provided in a region near the discharge tube 7 inside the block 9.

  Moreover, as shown in FIG. 5, the housing 21 which interrupts | blocks external air is provided. An opening is formed in the housing 21, and the block 9 is fitted into the opening so that the waveguide 1 is positioned outside the housing 21 and the wafer insertion port 12 a of the block faces the housing 21. The flange 9 c is fixed to the wall of the housing 21 by being fixed by the screw 31 through the seal member 32.

  A circular turntable 17 on which the wafer 16 is placed is disposed in the housing 21 and in front of the wafer insertion opening 12a of the block 9. A rotating shaft 17 a protruding from the back surface of the turntable 17 extends from the opening 21 a in the bottom wall of the housing 21 and is connected to a motor 18 disposed outside the housing 21. In this case, a bellows 22 is attached between the peripheral portion of the opening 21a of the housing bottom wall and the rotating shaft 17a so as to prevent intrusion of outside air.

  Further, the portion of the waveguide 1 to which the block 9 is attached is generally curved so that the second surface 9b of the block is inside, and as shown in FIG. In the projection onto the vertical plane, the plasma generation chamber 10 of the waveguide 1, the discharge tube 7, and the block 9 is positioned on a concentric circle centered on the center of the turntable 17, while the block 9 The second surface 9 b is curved with a smaller curvature than the wafer 16.

An actuator 23 is disposed on the upper wall of the housing 21, and a cylinder 23 a of the actuator 23 extends into the housing 21 from an opening 21 b on the housing upper wall. In this case, a bellows 24 is attached between the peripheral portion of the opening 21b on the upper wall of the housing and the cylinder 23a so as to prevent intrusion of outside air.
Further, a coating plate 28 that covers the wafer 16 placed on the turntable 17 is disposed inside the housing 21, and the coating plate 28 is connected to the cylinder 23 a. Thus, the covering plate 28 is moved by the actuator 23 and can take a closed position where the wafer 16 is covered with the gap 30 therebetween and an open position away from the wafer 16.

  The covering plate 28 has a plurality of gas inlets 29 for introducing an inert gas into the gap 30 between the covering plate 28 and the wafer 16 when the covering plate 28 is in the closed position (see FIG. 5). Provided. Further, an inert gas supply source (not shown) is disposed outside the housing 21, and the inert gas supply source and the gas inlet 29 are connected by an inert gas supply pipe (not shown).

An opening for supplying the wafer 16 into the housing 21 and taking out the wafer 16 from the housing 21 is formed in the wall portion of the housing 21 facing the wafer insertion opening 12a of the block 9, and a shutter is formed in the opening. 33 is attached.
Further, outside the housing 21, the wafer 16 is transferred to the turntable 17, and a part of the wafer 16 is inserted into the wafer insertion opening 12 a, and at the same time, the wafer 16 is aligned with the center of the turntable 17. By placing 16 on the turntable 17, the peripheral edge of the wafer 16 is introduced into the plasma generation chamber 10, and when the processing of the wafer 16 is completed, the wafer 16 is picked up from the turntable 17 and unloaded from the housing 21. A wafer transfer device (not shown) is arranged.
Although not shown, optical sensors for positioning the wafer 16 are arranged on both sides in the longitudinal direction of the wafer insertion opening 12 a of the block 9 and are used for positioning the wafer 16.

Next, an operation method of the plasma processing apparatus of the present invention will be described. In this embodiment, the pressure inside the housing 21 is equal to the atmospheric pressure, but the plasma processing apparatus of the present invention operates stably in the pressure range of atmospheric pressure to several tens of mTorr.
The covering plate 28 is moved to the open position by the actuator 23. Next, the microwave generated by the microwave generation source 2 is introduced into the waveguide 1 through the microwave supply path 3. At the same time, a reaction gas such as CF ₄ , oxygen, Cl ₂ , and SF _{6 is} supplied from the reaction gas supply source to the gas supply line 13 of the block 9 through the reaction gas supply pipe 15 and introduced into the plasma generation chamber 10. Is done. At this time, the reaction gas supplied to the gas supply line 13 is once stored in the buffer unit 13a, and then supplied to the plasma generation chamber 10 from the downstream side portion of the gas supply line 13 as a uniform flow. The gas is discharged to the outside through the gas discharge line 14. The reaction gas is heated to a predetermined temperature by the heater 25 while passing through the reaction gas supply line 13.

The reaction gas introduced into the plasma generation chamber 10 is converted into plasma by the electromagnetic field that has oozed into the plasma generation chamber 10 from the waveguide 1 through the slit 8 of the discharge tube 7 and the second passage 11 of the block 9. A line-shaped plasma is obtained along the plasma generation chamber 10. In this case, the plasma is generated by the electromagnetic field that oozes out from the slit 8 on the H surface of the waveguide 1, but the electromagnetic field that oozes out from the H surface has a characteristic of attenuating rapidly. Therefore, the plasma generated by the electromagnetic field that oozes out from the slit 8 on the H surface of the waveguide 1 is confined in the plasma generation chamber 10 and is generated in the second passage 12 of the block 9. Is prevented. As a result, plasma suitable for processing the peripheral edge of the wafer 16 is obtained.
Even if plasma is generated in the second passage 12 of the block 9, the plasma is confined in the plasma generation chamber 10 by the action of the mirror magnetic field trap magnet 27 provided in the vicinity of the wafer insertion opening 12 a. It is done.

  Then, the shutter 33 of the housing 21 is opened, and the wafer 16 is loaded into the housing 21 by the wafer transfer device and placed at a predetermined position on the turntable 17. When the loading of the wafer 16 is completed, the wafer transfer device is retracted from the housing and the shutter 33 is closed. Thereafter, the coating plate 28 is moved from the open position to the closed position by the actuator 23, and the inert gas is introduced into the gap 30 between the coating plate 28 and the wafer 16 from the inert gas inlet 29 of the coating plate 28. Is introduced. The introduced inert gas generates a gas flow toward the periphery of the wafer 16.

  When the wafer 16 is placed at a predetermined position on the turntable 17, a peripheral portion corresponding to a certain central angle of the wafer 16 is introduced into the plasma generation chamber 10 and subjected to plasma processing. At this time, particles or the like generated during processing are reliably removed to the outside of the wafer 16 by the gas flow of the inert gas. When this plasma processing is completed, the turntable 17 is rotated by the motor 18 and the next unprocessed peripheral edge portion of the wafer 16 is introduced into the plasma generation chamber 10 and similarly plasma processed.

  When the plasma processing of the peripheral portion is completed over the entire circumference of the wafer 16, the supply of the inert gas to the coating plate 28 is stopped, and the coating plate 28 is moved from the closed position to the open position. Then, the shutter 33 of the housing 21 is opened again, the wafer transfer device is introduced into the housing 21, and the wafer 16 is unloaded from the housing 21. Thereafter, a new unprocessed wafer 16 is transferred to the housing 21 by the wafer transfer device. It is carried in.

It is the perspective view which showed the structure of the principal part of the plasma processing apparatus by one Example of this invention. It is a figure which shows the structure of a discharge tube, (A) is a perspective view, (B) is a top view, (C) is a cross-sectional view. It is a perspective view of the waveguide with which the discharge tube was mounted | worn. It is a top view of the plasma processing apparatus by this invention. It is sectional drawing of the plasma processing apparatus by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Waveguide 2 Microwave generation source 3 Microwave supply path 4 Isolator 5 Microwave matching device 6 Short circuit plunger 7 Discharge tube 8 Slit 9 Block 10 Plasma generation chamber 11 1st channel | path 12 2nd channel | path 13 Gas supply tube Line 14 Gas discharge line 15 Reaction gas supply pipe 16 Wafer (object to be processed)
17 Turntable 18 Motor 19 Seal member 20 Screw 21 Housing 22 Bellows 23 Actuator 24 Bellows 25 Heater 26 Cooling water circulation path 27 Mirror magnetic field trap magnet 28 Cover plate 29 Inert gas inlet 30 Clearance 31 Screw 32 Seal member 33 Shutter

Claims (10)

A plasma processing apparatus for irradiating a peripheral portion of a disk-shaped workpiece with microwave discharge plasma and plasma processing the peripheral portion,
A waveguide with a flat rectangular cross-section into which microwaves are introduced;
A microwave source;
A microwave supply path for supplying microwaves from the microwave generation source to the waveguide, and a longitudinally long opening is formed in one side wall of the waveguide along the propagation direction of the microwave. In addition,
A dielectric discharge tube is mounted in the opening of the waveguide and extends along the opening, and a vertically long slit is formed along the opening in the wall portion of the discharge tube that does not face the waveguide. Formed, and
A block attached to a side wall of the waveguide including the discharge tube and surrounding the discharge tube;
A plasma generation chamber formed inside the block and extending along the discharge tube;
A first surface facing a side wall of the waveguide, and a second surface located on the opposite side of the first surface;
A first passage having a slot-like cross section extending from the plasma generation chamber to the inside of the block and opening to the first surface;
A second passage having a slot-like cross-section extending from the plasma generation chamber to the inside of the block and opening to the second surface, and the discharge tube is accommodated in the opening of the first passage. The opening of the second passage forms a workpiece insertion port,
The block further comprises:
A gas supply line for supplying gas to the plasma generation chamber; and a gas discharge line for discharging gas from the plasma generation chamber;
A reactive gas source;
A reaction gas supply pipe connecting the reaction gas supply source and the gas supply pipe;
A circular turntable disposed in front of the workpiece insertion port of the block, on which the workpiece is placed;
A motor connected to a rotating shaft projecting from the back surface of the turntable;
A covering plate for covering the workpiece placed on the turntable;
A covering plate moving mechanism for moving the covering plate up and down to take a closed position for covering the object to be processed with a gap therebetween and an open position away from the object to be processed; A plasma processing apparatus comprising:   The portion of the waveguide to which the block is attached is generally curved so that the second surface of the block is on the inside, and in the projection onto the surface perpendicular to the rotation axis of the turntable, The waveguide, the discharge tube, and the plasma generation chamber of the block are respectively located on the circumference of a concentric circle centering on the center of the turntable, while the second surface of the block is the processing target The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus is curved with a smaller curvature than the object.   The object to be processed is transported to the turntable, and a part of the object to be processed is inserted into the object to be processed insertion port, and at the same time, the center of the object to be processed coincides with the center of the turntable. The apparatus further includes a workpiece transfer device that introduces a peripheral portion of the workpiece into the plasma generation chamber by placing the workpiece on the turntable and then unloads the workpiece from the turntable. The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus is provided.   The coating plate is provided with a plurality of gas inlets for introducing an inert gas into the gap between the coating plate and the workpiece when the coating plate is in the closed position. The plasma processing according to any one of claims 1 to 3, further comprising: an active gas supply source; and an inert gas supply pipe connecting the inert gas supply source and the gas introduction port. apparatus.   5. The object detection sensor for positioning the object to be processed is disposed on each side of the block in the longitudinal direction of the object insertion port. 6. The plasma processing apparatus according to 1.   6. The plasma processing apparatus according to claim 1, wherein the discharge tube is provided on an H surface of the waveguide.   The plasma processing apparatus according to any one of claims 1 to 6, wherein a magnet for a mirror magnetic field trap is provided in the vicinity of the workpiece insertion port in the block.   The heater for heating the reaction gas supplied to the said plasma production | generation chamber is incorporated in the vicinity of the said gas supply pipe line in the inside of the said block, The any one of Claims 1-7 characterized by the above-mentioned. The plasma processing apparatus according to 1.   The plasma processing apparatus according to claim 1, wherein a cooling water circulation path is provided in the vicinity of the discharge tube inside the block.   The housing further includes a housing for shielding from outside air, and the turntable and the covering plate are accommodated inside the housing, and the second surface of the block is outside the housing on the outside of the housing. The block is attached so as to face the wall surface, and an opening with a shutter for carrying the object to be processed is provided in the housing on the wall surface of the housing facing the wall surface to which the block is attached. The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus is provided.

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