JP2005142368A - Plasma treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized plasma treatment device that is free from corrosion. <P>SOLUTION: The plasma treatment device is provided with an annular inner electric field impressing element 11, an outer ground electrode 21, and an insulating holder 30. The device is also provided with a metallic frame 40. The holder 30 comprises a work-side coating section 31, an opposite-side coating section 32, and an inner peripheral-side coating section 33. The frame 40 comprises a work-side coating section 41, an opposite-side coating section 42, and an inner peripheral-side coating section 43. The frame 40 also comprises an outer peripheral-side coating section 44. The coating section 44 is adapted to face the electrode 21 without interposing any insulating material and has an exhaust tube 83 which is passed through the section 44 in the axial direction and made of a corrosion-resistant resin. A process gas flowing through the gas passages 50 of the electrodes 11 and 21 is ionized to produce plasma and blown out toward the outer edge of a work W from the annular outlet port 71 of the coating section 31. By-products and the process gas are discharged through an exhaust passage 82 and the exhaust tube 83 from the annular inlet port 81 of the coating section 41. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a plasma processing apparatus that performs surface treatment on a workpiece in an annular shape.

  For example, when a film (eg, photoresist) is formed on a disk-shaped semiconductor wafer (work) by applying a raw material with a spin coater, the raw material liquid is dropped at the center while rotating the semiconductor wafer, and the entire area of the upper surface is applied by centrifugal force. Spread. As a result, a film is formed up to the outer edge portion of the upper surface of the wafer. If this film is left up to the outer edge, particles will be generated when the outer edge is gripped in subsequent steps. Therefore, a removal step is performed after the film formation step.

  In order to remove the outer edge portion of the wafer film as described above, for example, a plasma processing apparatus of Patent Document 1 has been proposed. In this plasma processing apparatus, an electric field is applied between the annular electrodes to convert the processing gas passing between the electrodes into plasma, this plasmaized processing gas is sprayed onto the outer edge of the wafer, and the outer edge of the film is removed by etching. Was.

By the way, the by-product film generated by the processing gas and etching causes an adverse effect on other regions of the wafer, and thus needs to be quickly removed. In view of this, the apparatus of Patent Document 1 is equipped with an exhaust means that is separate from the above-described process gas spraying means. The exhaust means has an annular suction port provided close to the outer peripheral edge of the wafer, and the processing gas and by-products are sucked and exhausted from the suction port.
JP-A-8-279494

  However, the apparatus of Patent Document 1 has a drawback that the apparatus is complicated and large because the means for blowing the plasma-ized processing gas and the means for exhausting are separately provided.

  Therefore, the present applicant has developed a plasma processing apparatus in which the above two means are incorporated in one unit (Japanese Patent Application No. 2002-352847). This device includes an annular inner electrode, an annular outer electrode arranged concentrically on the radially outer side of the inner electrode, an insulating holder that covers these electrodes over the entire circumference, and the holder over the entire circumference. And a metal frame for covering. The metal frame accommodates and holds the electrode and the holder, and also plays a role of preventing leakage.

  An annular gap between the outer peripheral surface of the inner electrode and the inner peripheral surface of the outer electrode is provided as a gas passage, and the processing gas flowing through the gas passage is turned into plasma by an electric field applied between these electrodes. An annular blowing port connected to the gas passage is formed in the workpiece-side covering portion of the holder, and the plasma-ized processing gas blows out from the blowing port toward the workpiece. An annular suction port is formed at a position corresponding to the blowing port in the covering portion on the work side of the frame. The holder and the frame are formed with an exhaust passage that connects the suction port to the suction means. And the by-product and process gas produced | generated with the workpiece | work surface treatment are exhausted to a suction means through an exhaust passage from a suction inlet.

  However, in the apparatus of the above-mentioned application, when the sucked processing gas and by-products pass through the exhaust passage formed by the through hole of the frame, there is a problem that the inner periphery is corroded. If a corrosion-resistant metal is used to prevent this inconvenience, the cost becomes high and there is room for improvement.

The present invention has been made to solve the above-described problems. An inner electrode having a ring shape, an outer electrode having a ring shape concentric with the inner electrode and disposed radially outside, and the inner electrode and the outer electrode are provided. An insulating holder that covers the entire circumference, and a metal frame that covers the entire circumference of the holder,
An annular gap between the outer peripheral surface of the inner electrode and the inner peripheral surface of the outer electrode is provided as a gas passage, and the processing gas flowing in the gas passage is turned into plasma by an electric field applied between these electrodes. And
An annular blowing port connected to the gas passage is formed in the workpiece-side covering portion of the holder, and the plasma-treated processing gas blows out from the blowing port toward the workpiece,
An annular suction port is formed at a position corresponding to the blow-out port in the work portion side cover of the frame, and at least the frame is formed with an exhaust passage connecting the suction port to the suction means. By-products and processing gas generated along with the workpiece surface treatment with plasmaized processing gas are exhausted from the suction port to the suction means through the exhaust passage,
The exhaust passage has an exhaust tube made of a corrosion-resistant resin that passes through the frame.

  According to the above configuration, the means for converting the processing gas into plasma and blowing it out and the means for sucking and exhausting the by-product and the processing gas can be incorporated into one unit, so that the configuration is simple. Further, since the exhaust passage in the metal frame is formed by the exhaust tube made of the corrosion resistant resin, the corrosion of the frame can be avoided at a low cost.

  Preferably, the frame has a cylindrical outer cover portion, and the exhaust tube penetrates the outer cover portion in the axial direction. According to this, exhaust can be led to the opposite side to a work. In addition, since the covering portion on the outer peripheral side of the frame is made of metal, the exhaust passage can be formed through the exhaust tube even if it is relatively thin, so that the diameter of the apparatus can be reduced.

  Preferably, the inner electrode serves as an electric field application electrode and the outer electrode serves as a ground electrode, and the holder further includes a covering portion on the opposite side of the work and a cylindrical covering portion covering the inner electrode, and the frame is Furthermore, it has a covering part on the opposite side of the workpiece and a cylindrical inner peripheral side covering part that covers the cylindrical covering part of the holder, and the outer peripheral side covering part of the frame does not pass through the insulating material, It is characterized by facing the electrode. According to this, since the insulating material is not interposed between the outer electrode and the plate, the diameter of the device can be further reduced. Since the outer electrode is a ground electrode, inconvenience such as electric leakage does not occur.

  Preferably, the work side covering portion of the frame is made of a corrosion-resistant metal, and a gap is formed between the covering portion and the work side covering portion of the holder, and the gap is formed between the suction port and the exhaust tube. Provided as an exhaust passage. According to this, the exhaust tube and the suction port on the outer peripheral side can be connected with a simple configuration.

  According to the present invention, it is possible to simplify the configuration of a plasma processing apparatus that performs surface treatment in an annular shape, and to avoid corrosion of a metal frame having an exhaust passage at low cost.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 show an atmospheric pressure plasma etching apparatus M (plasma processing apparatus) for processing a semiconductor wafer W (work). First, the wafer W will be described. The wafer W is formed in a disk shape by a semiconductor such as silicon. On the upper surface of the wafer W, a film Wa such as a photoresist is formed by, for example, a spin coater. The film Wa covers the entire upper surface of the wafer W and extends to the outer edge. If the outer edge portion Wa 'of the film Wa is left, it may become a hindrance in the subsequent polishing step or cause particles to be generated in the step of gripping the outer edge. Therefore, the wafer W is sent to the atmospheric pressure plasma etching apparatus after the film forming process and is subjected to the etching process of the outer edge Wa ′.

  As shown in FIGS. 1 and 2, the atmospheric pressure plasma etching apparatus M includes a nozzle head 1 that is annular in plan view, a pulse power source 60 (electric field applying means), a processing gas source 70, and a suction pump 80 (suction means). And a refrigerant source 90 (temperature control medium source). The nozzle head 1 includes an inner electrode structure 10, an outer electrode structure 20, an insulating holder 30 that covers the electrode structures 10 and 20, and a metal (conductive) frame 40 that covers the holder 30. Yes. These components 10, 20, 30, and 40 are all ring-shaped.

  The inner electrode structure 10 includes an annular electrode 11 (inner electrode) and an annular metal passage forming member 15 arranged concentrically on the inner side in the radial direction of the electrode 11. A passage 17 is formed. The outer electrode structure 20 has a larger diameter than the inner electrode structure 10 and is disposed concentrically on the outer side in the radial direction. The outer electrode structure 20 also includes an annular electrode 21 (outer electrode) and an annular metal passage forming member 25 arranged concentrically on the radially inner side of the electrode 21, and a medium passage between the two. 27 is formed. An annular gap 50 is formed between the inner peripheral surface of the electrode 21 and the outer peripheral surface of the electrode 11. The gap 50 becomes a gas passage for the processing gas. A solid dielectric is coated on the outer peripheral surface of the electrode 11 and the inner peripheral surface of the electrode 21 by thermal spraying.

  The holder 30 includes a substantially horizontal bottom plate 31 (covering portion on the workpiece side), a substantially horizontal top plate 32 (covering portion on the opposite side of the workpiece), and a cylinder 33 sandwiched between the inner peripheral portions thereof. (Cylindrical covering portion) and an annular ring member 34 are provided. These members are made of an insulating material such as polytetrafluoroethylene (corrosion resistant resin). The ring member 34 is fitted in a space formed by the step between the upper end surfaces of the electrodes 11 and 21 and the passage forming members 15 and 25. The bottom plate 31 and the top plate 32 sandwich the electrode structures 10 and 20 and the ring member 34. The cylinder 33 is in contact with and supports the inner periphery of the passage forming member 15 of the inner electrode structure 10. The bottom plate 31 is divided into an outer side and an inner side.

  The frame 40 that surrounds and supports the holder 30 is sandwiched between a bottom plate 41 (work-side covering portion) that is substantially horizontal and a top plate 42 (covering portion on the opposite side of the workpiece) that is substantially horizontal. And an outer cylinder 44 (a cylindrical outer covering portion) and an inner cylinder 43 (a cylindrical inner covering portion) and an outer cylinder 44 connected by bolts or the like. These members 41 to 44 are made of a metal such as aluminum or stainless steel. The bottom plate 41 holds the bottom plate 31 of the holder 30 through spacers 49 that are radially arranged at equal intervals. The top plate 42 holds the top plate 32 of the holder 30. The inner cylinder 43 holds down the inner periphery of the cylinder 33 of the holder 30 and the top plate 32. The outer cylinder 44 is in contact with the outer periphery of the electrode 21, the passage forming member 25, and the top plate 32 to hold it. A member made of an insulating material is not interposed between the outer cylinder 44 and the electrode 21. The top plate 42 is fixed to a gantry (not shown), whereby the nozzle head 1 is supported. The bottom plate 41 is made of a corrosion-resistant metal (for example, trade name Hastelloy), divided into an inner side and an outer side, and a thin plate 45 made of an insulating material is attached to the lower surface thereof.

  As shown in FIG. 2, a connection terminal 62 is provided through the top plate 42 of the frame 40 through an insulating cylinder 61, and the lower end of the connection terminal 62 is connected to the upper end of the passage forming member 15. ing. A pulse power supply 60 is connected to the connection terminal 62 via a feed line 63. Thereby, the electrode 11 is connected to the pulse power source 60 and becomes an electric field application electrode (hot electrode). In addition, the electrode 21 is grounded via the passage forming member 25 and the frame 40, thereby forming a ground electrode (ground electrode).

As shown in FIG. 1, an annular blowing port 71 is formed between members divided into the outside and the inside of the bottom plate 31. The upper end of the outlet 71 is connected to the gas passage 50 between the electrodes 11 and 21, and the lower end thereof is opened by a mountain-shaped annular protrusion 31 a formed on the lower surface of the bottom plate 31. On the other hand, a plurality of joints 72 are attached to the top plate 42 of the frame 40 at equal intervals in the circumferential direction. The joint 72 has a gas passage 50 between the electrodes 11 and 21 through a hole 73 (supply passage) formed in the top plates 32 and 42 and the ring member 34 and an annular slit 74 (supply passage) formed in the ring member 34. It is connected to the upper end of. A processing gas source 70 is connected to the joint 72 via a supply pipe 75. For example, CF ₄ is stored in the processing gas source 70 as an etching gas.

  As best shown in FIG. 3, an annular suction port 81 having a taper corresponding to the inclined surface of the annular convex portion 31a is formed between members divided into the inner side and the outer side of the bottom plate 41. Yes. The suction port 81 is located directly below the blowing port 71 and has a width wider than that, and is connected to an exhaust passage 82 formed by a gap between the bottom plates 31 and 41. Further, an exhaust tube 83 (exhaust passage) made of a plurality of corrosion-resistant resins such as polytetrafluoroethylene passes through the outer cylinder 44 of the frame 40 at equal intervals in the circumferential direction. The lower ends of these exhaust tubes 83 are connected to the exhaust passage 82 via through holes 84 formed in the bottom plate 31. The upper end of the exhaust tube 83 is inserted and connected to a joint 85 installed on the top plate 42.

  A plurality of exhaust tubes 86 (exhaust passages) made of a corrosion-resistant resin such as polytetrafluoroethylene pass through the cylinder 33 and the top plate 32 of the holder 30 at equal intervals in the circumferential direction. The lower ends of these exhaust tubes 86 are connected to the exhaust passage 82 through through holes 87 formed in the bottom plate 31. The upper end portion of the exhaust tube 86 is inserted and connected to a joint 88 installed on the top plate 42. The joints 85 and 88 are connected to the suction pump 80 via a suction pipe 89 made of a corrosion-resistant resin.

  An inlet side joint 91 and an outlet side joint 92 are attached to the top plate 42. The inlet side joint 91 is connected to a refrigerant source 90 (temperature control medium source) via a refrigerant supply pipe 93. For example, water is used as the refrigerant (temperature control medium), and the refrigerant source 90 includes a water supply pump. The inlet-side joint 91 is connected to the medium passage 17 of the inner electrode structure 10 through the top plates 42 and 32 and the through holes 94 formed in the passage forming member 15. A drainage tube 95 is connected to the outlet side joint 92. The outlet side joint 92 is connected to the medium passage 27 of the outer electrode structure 20 through the top plates 42 and 32 and the through holes 96 formed in the passage forming member 25. Further, two relay joints (not shown) are attached to the top plate 42 at a position approximately 180 ° away from the joints 91 and 92. These relay joints are connected by a relay tube (not shown). These relay joints are connected to the medium passage 17 of the inner electrode structure 10 and the medium passage 27 of the outer electrode structure 20 in the same manner as the joints 91 and 92 described above.

  The operation of the atmospheric pressure plasma etching apparatus M configured as described above will be described. A wafer W to be processed is set below the nozzle head 1. At this time, the center axis of the nozzle head 1 and the center of the wafer W are made to coincide. As a result, the outer edge portion of the wafer W is positioned directly below the annular outlet 71.

  Next, the processing gas from the processing gas source 70 is uniformly introduced to the entire circumference of the gas passage 50 (annular plasma space) through the supply pipe 75, the joint 72, the hole 73, and the annular slit 74. In parallel, a pulse voltage is output from the pulse power supply 60 at a predetermined frequency. This pulse voltage is applied to the electrode 11 through the power supply line 63, the connection terminal 62 and the passage forming member 15. Thereby, a pulse electric field is formed in the gas passage 50 between the electrodes 11 and 21, and the processing gas passing through the gas passage 10a can be turned into plasma by this electric field. This plasma-ized processing gas is blown out from the entire circumference of the annular blow-out port 71 and blown around the entire circumference of the outer edge of the wafer W. As a result, the outer edge Wa ′ of the film Wa of the wafer W can be etched all at once over the entire circumference.

  The suction pump 80 is driven simultaneously with the blowing of the processing gas. As a result, an upward suction flow is formed in the immediate vicinity so as to surround the blowing flow, and by-products generated by processing gas and etching can be prevented from flowing inward from the outer edge Wa ′ along the wafer W. The non-target film Wa can be protected. Process gas and by-products after etching are sucked into the suction port 81 and exhausted through the exhaust passage 82, the exhaust tubes 83 and 86, and the suction tube 89.

  Further, the refrigerant of the refrigerant source 90 is sent to the medium passage 17 of the inner electrode structure 10 through the supply pipe 93, the inlet side joint 91, and the through hole 94. This refrigerant is divided into two hands and flows in the medium passage 17, flows into the medium passage 27 of the outer electrode structure 20 through a relay joint and a relay tube separated by about 180 °, and further flows into the medium passage 27 in two hands. Finally, the water is discharged from the drain tube 95 through the through hole 96 and the outlet side joint 92. As described above, in the process of flowing through the medium passages 17 and 27, the electrodes 11 and 21 generated by the discharge are cooled and adjusted so as to be in a predetermined temperature range.

  The processing gas and the by-product have a property of corroding metal, but the metal bottom plate 41 forming the exhaust passage 82 is made of a corrosion-resistant metal, so that corrosion is avoided. Further, since the exhaust passage of the outer cylinder portion 44 is formed by the exhaust tube 83 made of corrosion-resistant resin, corrosion of the outer cylinder portion 44 can be avoided. Since the exhaust passage of the outer cylinder portion 44 is simply inserted through the exhaust tube 83 through a through hole extending in the axial direction, corrosion resistance can be obtained at a low cost.

In the present embodiment, the connection terminal 61 and the joints 72, 85, 88, 91, 92 are installed on the top plate 42 of the frame 40, and are connected to the power source 80, the processing gas source 70, the suction pump 80, and the refrigerant source 90. The structure can be simplified.
Further, since no constituent member (a member corresponding to the outer cylinder of the holder 30) made of an insulating material is interposed between the outer cylinder 44 of the frame 40 and the outer electrode structure 20, the outer diameter of the head 1 is reduced. can do. Since the joint 85 is on the top plate 42 as described above, it is necessary to form the outer peripheral exhaust passage in the outer cylinder 44, but there is no inconvenience caused by using the exhaust tube 83 as described above.

  The present invention is not limited to the above embodiment, and various forms can be adopted. For example, the present invention is not limited to etching, and can be applied to other plasma surface treatments such as cleaning and film formation. Further, the present invention can be applied not only to normal pressure but also to plasma surface treatment under reduced pressure.

It is a longitudinal cross-sectional view of the nozzle head of the atmospheric pressure plasma etching apparatus which concerns on one Embodiment of this invention. It is the figure which made the said nozzle head the longitudinal cross-section in the position different from FIG. It is an enlarged longitudinal cross-sectional view which shows the structure of the exhaust passage of the nozzle head.

Explanation of symbols

11 Inner structure (electric field application electrode)
21 Outer electrode (ground electrode)
30 Holder 31 Bottom plate (workpiece side coating)
32 Top plate (covering part on the opposite side of the workpiece)
33 cylinder (cylindrical covering part)
40 Frame 41 Bottom plate (work side coating)
42 Top plate (covering part on the opposite side of the workpiece)
43 Inner cylinder (cylindrical inner periphery side covering part)
44 Outer cylinder (cylindrical outer peripheral side covering part)
50 Gas passage 71 Outlet 81 Suction port 82 Exhaust passage 83 Exhaust tube (exhaust passage)
80 Suction pump (suction means)

Claims (4)

An annular inner electrode, an annular outer electrode concentric with the inner electrode and disposed radially outward, an insulating holder covering the inner electrode and the outer electrode over the entire circumference, and the holder With a metal frame covering the entire circumference,
An annular gap between the outer peripheral surface of the inner electrode and the inner peripheral surface of the outer electrode is provided as a gas passage, and the processing gas flowing in the gas passage is turned into plasma by an electric field applied between these electrodes. And
An annular blowing port connected to the gas passage is formed in the workpiece-side covering portion of the holder, and the plasma-treated processing gas blows out from the blowing port toward the workpiece,
An annular suction port is formed at a position corresponding to the blow-out port in the work portion side cover of the frame, and at least the frame is formed with an exhaust passage connecting the suction port to the suction means. By-products and processing gas generated along with the workpiece surface treatment with plasmaized processing gas are exhausted from the suction port to the suction means through the exhaust passage,
The plasma processing apparatus, wherein the exhaust passage has an exhaust tube made of a corrosion-resistant resin that passes through the frame.   2. The plasma processing apparatus according to claim 1, wherein the frame has a cylindrical outer cover portion, and the exhaust tube penetrates the outer cover portion in the axial direction.   The inner electrode serves as an electric field application electrode, and the outer electrode serves as a ground electrode. The holder further includes a covering portion on the opposite side of the workpiece and a cylindrical covering portion covering the inner electrode, and the frame further includes a workpiece. And a cylindrical inner peripheral covering portion that covers the cylindrical covering portion of the holder, and the outer peripheral covering portion of the frame is opposed to the outer electrode without an insulating material interposed therebetween. The plasma processing apparatus according to claim 2, wherein:   The work side covering portion of the frame is made of a corrosion-resistant metal, and a gap is formed between the covering portion and the work side covering portion of the holder, and this gap connects the suction port and the exhaust tube. The plasma processing apparatus according to claim 2, wherein the plasma processing apparatus is provided as an exhaust passage.

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