JP2008182176A - Plasma machining apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma machining apparatus uniformly machining a surface to be machined of a workpiece. <P>SOLUTION: In an inner area in the diameter direction of a rotary shaft 23 than an area positioned in the outermost side in the diameter direction of the rotary shaft 23 in the electrode 33 where a substrate stage 24 side is opposed to surface 34, the shape of the opposed surface 34 is formed so that the peripheral-direction length of the opposed surface 34 is gradually increased to the outer direction of the diameter direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus for processing a material to be processed using plasma. In particular, the present invention is preferably used for processing a semiconductor material such as silicon or a group III nitride semiconductor, or an insulator material such as glass. The present invention relates to a plasma processing apparatus. The present invention also relates to a plasma processing apparatus that is preferably used for processing a semiconductor substrate such as a silicon substrate or a group III nitride substrate, or an insulating substrate such as a glass substrate. The present invention relates to a plasma processing apparatus suitable for use in manufacturing elements such as light-emitting diodes and laser diodes using group nitride semiconductors.

  With the recent miniaturization of semiconductor device structures, the processing accuracy required for various semiconductor substrates has reached the nano-order level, and at the same time, the processing requires distortion-free processing that does not damage the surface. Has been. In machining that involves physical phenomena such as plastic deformation, ductility and brittle fracture, since the work is progressed by positively introducing strain into the work, the work surface is inevitably damaged. As a processing method capable of processing without distortion without damaging the surface of the workpiece and having excellent processing accuracy, a method using a radical reaction called plasma CVM is known.

  Plasma CVM causes neutral radicals generated at high density by plasma to act on the workpiece surface, and generates a compound by chemical reaction between constituent atoms and molecules on the workpiece surface and neutral radicals. This is a non-strain processing method in which the workpiece is processed by vaporizing it.

  Patent Document 1 describes the basic principle of plasma CVM, and Patent Document 2 describes a detailed apparatus configuration capable of performing plasma CVM. Patent Document 3 describes a method for realizing high-speed and high-efficiency machining. Patent Document 4 forms an axially symmetric minimum machining mark to realize high-speed and high-precision machining. A method is described.

  When plasma is generated and processed under a pressure near atmospheric pressure, the distance between the electrode and the workpiece needs to be kept narrow in order to maintain the plasma. Therefore, when a parallel plate type electrode generally used in a low-pressure plasma process is applied to an atmospheric pressure plasma process, it becomes difficult for fresh gas to be supplied to the central portion of the electrode, and the processing speed becomes non-uniform.

  In order to solve this problem, Patent Literature 3 and Patent Literature 4 employ a method of supplying fresh gas to the narrow gap portion by rotating the electrode.

However, in this case, the plasma becomes local in the form of dots or lines, and when processing a large area or a plurality of workpieces, the electrodes or workpieces are scanned over the entire workpiece. It is necessary to do so, and the efficiency becomes worse. Further, when processing is performed in a vacuum apparatus, there is a problem that it is difficult to avoid an increase in the size of the apparatus main body due to substrate scanning.
Japanese Patent No. 2521127 Japanese Patent No. 2816365 Japanese Patent No. 3069271 JP 2006-22392 A

  Therefore, the present inventor made a prototype of an electrode structure and a processing apparatus shown below in order to process a large area substrate or a plurality of workpieces, and verified the effect.

  FIG. 1A is a schematic side perspective view of a processing apparatus prototyped by the present inventor (not known at the time of the present application, and therefore not prior art), and FIG. 1B is a processing apparatus shown in FIG. 1A. It is the schematic of the electrode peripheral part.

  As shown in FIG. 1A, this processing apparatus includes a reaction vessel 1, a rotating electrode 2, a substrate stage 4, a heater 5, and a high-frequency power source 7. The reaction vessel 1 includes a gas introduction line 8 and a gas exhaust line. 9 is connected. The rotating electrode 2 and the substrate stage 4 are disposed in the reaction vessel 1, and the heater 5 is built in the substrate stage 4. A part of the surface of the rotating electrode 2 is disposed substantially parallel to the mounting surface of the workpiece 6 of the substrate stage, and a part of the surface of the rotating electrode 2 faces the mounting surface of the substrate stage. ing. A workpiece 6 is placed on the placement surface of the substrate stage 4, and plasma 10 is generated between the non-workpiece 6 and a part of the surface of the rotating electrode 2.

  As shown in FIG. 1B, the rotating electrode 2 has an electrode portion 11 and a rotating shaft 3. The electrode part 11 has a rod-like electrode shape, and as a result, the plasma 10 generated between the non-processed object 6 and one surface of the rotating electrode 2 is substantially the same as the work piece 6. It has a parallel line shape. The rotating shaft 3 extends in the normal direction of the mounting surface of the substrate stage 4 from the center of the surface of the electrode unit 11 opposite to the substrate stage 4 side. The rotating electrode 2 is rotatable about the rotating shaft 3.

  The present inventor uses the apparatus described above to contact the workpiece 6 while rotating a line-shaped plasma substantially parallel to the workpiece 6, thereby narrowing the gap between the parallel plates. It was thought that the problem that the gas was hardly supplied to the part (plasma processing part) could be solved and the workpiece 6 could be processed uniformly. However, when the effect was verified, it was found that the following problems became apparent.

  FIG. 2 is a diagram showing an example of a cross-sectional profile of a processing trace obtained when a silicon substrate is processed by the plasma processing apparatus shown in FIG. 1A.

  As shown in FIG. 2, in this example, the whole is not processed uniformly, and the processing amount decreases as the distance from the position immediately below the rotating shaft 3 increases. That is, the substrate cannot be processed uniformly.

  Accordingly, an object of the present invention is to provide a plasma processing apparatus capable of uniformly processing a workpiece, and in particular, to provide a plasma processing apparatus capable of processing a large area substrate and a plurality of substrates uniformly and efficiently. There is.

In order to solve the above problems, a plasma processing apparatus according to the present invention comprises:
A workpiece holding section for holding the workpiece in a predetermined position;
In a state where the rotary shaft and the workpiece are held at the predetermined position, the workpiece has an opposing surface that faces the axial direction of the rotary shaft and extends substantially perpendicular to the axial direction. And a rotating electrode having an electrode portion connected to one end of the rotating shaft,
In the region inward of the radial direction with respect to the radially outermost portion of the rotating shaft on the facing surface, the circumferential length of the rotating shaft of the facing surface is outside the radial direction. The feature is that it gets bigger as you go.

  The inventor has found that the shape of the generated plasma is a shape corresponding to the shape of the facing surface of the electrode portion.

  Further, the present inventor found that the plasma contact time at each point of the silicon substrate is different and that the cause is that the plasma contact time decreases toward the end of the electrode. It has been found that the amount is large because the region where the plasma is always in contact is generated according to the width of the plasma, so that the processing speed is increased as compared with the peripheral portion.

  In addition, in the electrode structure shown in FIG. 1B, the present inventor has determined that the width in the circumferential direction of the plasma (exactly the circumferential direction of the rotating shaft) is independent of the position in the radial direction (exactly the radial direction of the rotating shaft). Since it is constant, it has been found that the plasma contact time increases in the workpiece as it goes directly below the electrode rotation axis (inward in the radial direction), and the machining speed becomes non-uniform.

  According to the present invention, the circumferential length of the rotating shaft of the facing surface is greater in the radially inner region than the radially outermost portion of the rotating shaft on the facing surface. Since it increases as it goes outward in the radial direction, the workpiece can be uniformly processed throughout the plasma processing portion, regardless of the distance from the one end of the rotating shaft, that is, The workpiece can be processed uniformly and efficiently regardless of the radial position of the rotating shaft.

  In the plasma processing apparatus according to an embodiment, the facing surface includes a plurality of regions having a circumferential width that increases toward the outside in the radial direction.

  According to the embodiment, the workpiece can be processed uniformly and efficiently with a simple configuration.

  Further, the plasma processing apparatus according to one embodiment is configured such that when the electrode portion rotates in one direction with respect to the workpiece holder, the end surface on the front side of the rotation of the electrode portion is in contact with the end surface. Is a shape that promotes movement between the facing surface and the workpiece held at the predetermined position.

  According to the embodiment, in addition to being able to process the workpiece uniformly and efficiently with a simple configuration, the gas in contact with the end surface is promoted to move between the facing surface and the workpiece. Thus, the reaction gas can be efficiently introduced into the reaction region. Accordingly, the processing efficiency can be further improved.

  Further, in the plasma processing apparatus according to an embodiment, when the electrode portion rotates in one direction with respect to the workpiece holding portion, the end surface on the front side of the rotation of the electrode portion is in contact with the end surface. It is a shape that promotes the movement of gas toward the rotating shaft side of the electrode portion.

  According to the above embodiment, in addition to being able to process the workpiece uniformly and efficiently with a simple configuration, the gas in contact with the end face can be promoted to move to the rotating shaft side of the electrode part, Along with the movement of the gas, the residual material remaining on the workpiece surface can be moved out of the reaction region. Therefore, residual deposits can be reduced and plasma processing can be performed with high accuracy.

  In the plasma processing apparatus of one embodiment, when the electrode unit rotates in the first direction with respect to the workpiece holding unit, the front end surface of the electrode unit rotates in contact with the end surface. The shape of the electrode portion facilitates the movement of the gas to be moved between the facing surface and the workpiece held at the predetermined position, while the electrode portion has the second shape with respect to the workpiece holding portion. In the case of rotating in the second direction opposite to the one direction, the end surface on the front side of the rotation of the electrode portion promotes that the gas in contact with the end surface moves to the rotating shaft side of the electrode portion. Shape.

  According to the above embodiment, in addition to being able to process the workpiece uniformly and efficiently with a simple configuration, the gas contacting the end face is moved between the facing surface and the workpiece, or The gas in contact with the end face can be moved to the rotating shaft side of the electrode part. Accordingly, since an optimal air flow can be generated as appropriate based on the plasma processing content, the effect that the plasma processing speed can be increased and the residual material remaining on the surface of the workpiece are moved out of the reaction region. It is possible to realize both of the effects of being able to efficiently discharge and reducing the residual deposits. Therefore, plasma processing can be performed quickly and with high accuracy.

  In the plasma processing apparatus of one embodiment, the electrode part has a plate-like base part and a plurality of protrusions protruding from the base part, and the opposing surface is opposite to the base part of the protrusions. Is a combination of the two.

  According to the embodiment, the circumferential length of the facing surface can be precisely adjusted at each radial position, and the accuracy of processing the workpiece uniformly can be significantly improved. .

  Further, in the plasma processing apparatus of one embodiment, a plurality of holes are opened in the facing surface, and the density per unit area of the holes is decreased as going outward in the radial direction.

  According to the embodiment, the circumferential length of the facing surface can be precisely adjusted at each radial position, and the accuracy of processing the workpiece uniformly can be significantly improved. .

  In the plasma processing apparatus of one embodiment, the workpiece holding unit has a plurality of workpiece holding positions for holding the workpiece at predetermined intervals in the circumferential direction, and the workpiece holding position is at the workpiece holding position. A rotation device is provided for rotating the held workpiece.

  According to the embodiment, since the workpiece can be rotated by the rotation device at the time of processing, the workpiece can be processed efficiently, and the workpiece can be processed uniformly. Accuracy can be improved.

  The plasma processing apparatus according to an embodiment generates a line-shaped plasma substantially parallel to the workpiece between the workpiece and the electrode under atmospheric pressure or a pressure near atmospheric pressure, A plasma processing apparatus for processing by contacting with a surface of a workpiece, wherein the electrode rotates around a rotation axis perpendicular to the workpiece, and plasma is generated in the entire plasma contact portion during electrode rotation. The electrode shape is such that the contact times are equal.

  According to the plasma processing apparatus of the above-described embodiment, it is possible to efficiently supply a gas at a narrow interval between the electrode and the workpiece, and the plasma contact time in the circumferential direction around the electrode rotation axis The non-uniformity can be eliminated. Therefore, a large area and a plurality of workpieces can be processed uniformly and efficiently with a simple configuration.

  In the plasma processing apparatus of one embodiment, the electrode width increases from directly below the rotation axis toward the electrode end.

  In one embodiment of the plasma processing apparatus, the electrode has a large number of needle-like protrusions on the surface facing the workpiece, and the density of the needle-like protrusions extends from the rotation axis toward the electrode end. Has increased.

  Further, in the plasma processing apparatus of one embodiment, the electrode has a large number of holes perpendicular to the workpiece, and the density of the holes decreases from the rotation axis toward the end of the electrode. Yes.

  Moreover, the plasma processing apparatus of one embodiment has a substrate holder on which a plurality of workpieces can be radially arranged around the rotation axis, and each workpiece is rotated. .

  According to the plasma processing apparatus of the present invention, a workpiece can be processed uniformly and efficiently regardless of the radial position of the rotating shaft.

  In addition, according to the plasma processing apparatus of one embodiment, since the atmospheric pressure plasma generated under atmospheric pressure or a pressure near atmospheric pressure is used, the absolute number of neutral radicals that contribute to the processing of the workpiece can be increased. Thus, the chemical reaction between the neutral radical and the workpiece constituent atoms can be increased. Therefore, the processing speed of the workpiece can be improved.

  In addition, since there are many atoms and molecules in the atmospheric pressure plasma, ions in the atmospheric pressure plasma collide with some atoms and molecules before reaching the surface of the workpiece, Ions do not reach the surface of the workpiece directly. Therefore, the surface of the workpiece is not damaged during processing, and the surface of the workpiece can be made a surface that is not crystallographically disturbed.

  Furthermore, it is possible to eliminate the need for reaction vessels and powerful exhaust systems that are strong enough to create a low-pressure atmosphere, which can reduce equipment costs and reduce the cost of the final product. Can be realized.

  Furthermore, a large substrate and a plurality of substrates can be processed uniformly and efficiently after realizing the above-described effects.

  Further, according to the plasma processing apparatus of one embodiment, the end surface on the front side of the rotation of the electrode portion has a shape that promotes the movement of the gas contacting the end surface between the facing surface and the workpiece. Therefore, neutral radicals that contribute to the processing of the workpiece can be forcibly supplied to the surface of the workpiece, and the processing speed of the workpiece can be improved.

  Moreover, according to the plasma processing apparatus of one embodiment, the end surface on the front side of the rotation of the electrode portion has a shape that promotes the movement of the gas in contact with the end surface to the rotation axis side of the electrode portion. Residual substances remaining on the workpiece surface can be efficiently discharged out of the reaction region, the amount of residual deposits on the workpiece surface can be reduced, and plasma processing can be performed with high accuracy. it can.

  According to the plasma processing apparatus of one embodiment, when the electrode portion rotates in the first direction with respect to the workpiece, the end surface on the front side of the rotation of the electrode portion is opposed to the gas contacting the end surface. While having a shape that promotes movement between the surface and the workpiece, the electrode portion rotates in the second direction opposite to the first direction with respect to the workpiece, The front end surface of the electrode portion rotation has a shape that promotes the movement of the gas in contact with the end surface toward the rotation shaft side of the electrode portion. It can be created appropriately, the processing speed can be improved, and the residual material remaining on the surface of the workpiece can be efficiently discharged out of the plasma, and the residual deposits can be reduced.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 3A is a schematic side perspective view of the plasma processing apparatus according to the first embodiment of the present invention.

  This processing apparatus includes a reaction vessel 21, a rotating electrode 22, a substrate stage (substrate holder) 24 as an example of a workpiece holding unit, a heater 25, and a high-frequency power source 27. The reaction vessel 21 includes a gas introduction line 28, The gas exhaust line 29 is connected.

  The reaction vessel 21 defines an internal space serving as a reaction field for plasma processing the workpiece 26. The rotating electrode 22 and the substrate stage 24 are disposed in the internal space, and the substrate stage 24 is disposed substantially parallel to the bottom surface of the reaction vessel 21. The substrate stage 24 has a placement surface 31 on which the workpiece 26 is placed.

  The rotating electrode 22 has a rotating shaft 23 and an electrode portion 33. The rotating shaft 23 extends in the normal direction of the mounting surface 31 from the surface of the electrode portion 33 opposite to the substrate stage 24 side. The rotating shaft 23 is provided above the substrate stage 24 in the internal space so as to be perpendicular to the mounting surface of the substrate stage 24.

  The electrode portion 33 is connected to one end of the rotating shaft 23 on the substrate stage 24 side. The electrode portion 33 has a facing surface 34 that faces the workpiece 26 in the axial direction of the rotary shaft 23 and extends substantially perpendicular to the axial direction. The facing surface 34 is substantially parallel to the mounting surface of the workpiece 26 of the substrate stage (substrate holder) 24. The rotating shaft 23 can be rotated in the direction indicated by the arrow a in FIG. 3A, and the rotating electrode 22 is a mechanism that can rotate around the rotating shaft 23.

  The placement surface 31 and the facing surface 34 of the electrode portion 33 are substantially parallel to each other with a gap therebetween. Plasma 30 is generated between the non-processed product 26 placed on the placement surface 31 and the facing surface 34 of the electrode portion 33.

  The high frequency power supply 27 is provided outside the reaction vessel 21. The high frequency power supply 27 is connected to the rotating shaft 23 without obstructing the rotation of the rotating shaft 23. The substrate stage 24 has an earth part (not shown) that extends to the outside of the reaction vessel 21 and is grounded. The heater 25 is built in the substrate stage 24. The heater 25 plays a role of heating the workpiece 26 placed on the substrate stage 24.

  The rotating electrode 22 is movable in the vertical direction. By moving the rotary electrode 22 in the vertical direction, the distance between the electrode portion 33 and the substrate stage 24 positioned below the electrode portion 33 is appropriately changed. The substrate stage 24 is provided with a vacuum chuck (not shown) for attracting and fixing the workpiece 26 placed on the substrate stage 24, and the workpiece 26 during plasma processing is placed thereon. It is fixed so as not to deviate from the position.

  The gas introduction line 28 is provided on the first side of the reaction vessel 21. The gas introduction line 28 is connected to a gas cylinder or the like (not shown) that supplies gas. A gas is introduced into the internal space of the reaction vessel 21 through the gas introduction line 28.

  The gas exhaust line 29 is provided on the second side of the reaction vessel 21 facing the first side. The gas exhaust line 29 is connected to a pump (not shown) for sucking gas outside the reactor 21. The gas in the internal space of the reaction vessel 21 is discharged through the gas exhaust line 29.

  FIG. 3B is a schematic perspective view showing a part of the apparatus shown in FIG. 3A, and is a perspective view showing the periphery of the rotating electrode 22.

  The rotation shaft 23 extends substantially perpendicular to the placement surface 31 of the substrate stage 24. A plurality of workpieces 26 are arranged radially at predetermined intervals in the circumferential direction of the rotating shaft 23. The electrode part 33 has a rod-like shape. One end of the rotating shaft 23 on the substrate stage 24 side is connected to the center of the surface of the electrode portion 33 opposite to the substrate stage 24 side. The opposing surface 34 of the electrode portion 33 has an electrode width that decreases from the end portion of the electrode portion 33 toward directly below the rotation shaft 23.

  Specifically, the facing surface 34 includes two regions, a first region 37 and a second region 38, and each of the first region 37 and the second region 38 is outward in the radial direction of the rotating shaft 23. The circumferential width increases with time.

  In this way, in the shape corresponding to the shape of the surface of the electrode portion 33 on the substrate stage side, that is, in the cross section parallel to the mounting surface 31 of the substrate stage 24, the width is narrowed from one end portion toward the center. At the same time, plasma is generated in such a shape that the width becomes narrower from the other end toward the center.

  FIG. 3C is a schematic plan view of the rotating electrode 22 as viewed from the workpiece 26 side.

  As shown in FIG. 3C, the first region 37 has a fan-like shape whose width decreases linearly from one end of the electrode portion 33 on the side far from the rotation shaft 23 toward just below the rotation shaft 23. The second region 38 has a fan shape whose width decreases linearly from one end of the electrode portion 33 on the side far from the rotation shaft 23 toward directly below the rotation shaft 23.

  The center line of the first region 37 (line that bisects the first region 37 in the circumferential direction) and the center line of the second region 38 (line that bisects the second region 38 in the circumferential direction) are approximately Located on the same straight line. The central angle of the first region 37 and the central angle of the second region 38 are the same angle (indicated by α).

  Using the apparatus configured as described above, for example, the processing surface of the workpiece 26 is processed with plasma as follows.

  First, the gas inside the reaction vessel 21 is moved in the direction indicated by the arrow c in FIG. 3A by the gas exhaust line 29 to sufficiently exhaust the internal gas, and then the reaction gas is supplied from the gas introduction line 28 to the reaction vessel 1. It is introduced in the direction indicated by the arrow b in FIG. 3A. The pressure inside the reaction vessel 21 after the reaction gas is introduced is set to atmospheric pressure or a pressure near atmospheric pressure.

  Next, processing conditions such as the rotational speed of the rotary electrode 22, the distance between the rotary electrode 22 and the workpiece 26 placed on the substrate stage 24, and the temperature of the heater 25 that heats the workpiece 26. Set.

  Next, high-frequency power is applied from the high-frequency power source 27 to the electrode portion 33 via the rotating shaft 23. By applying high-frequency power to the electrode part 33, an electric field is generated between the electrode part 33 and the substrate stage 2. This electric field decomposes and excites the reaction gas supplied between the electrode portion 33 and the surface of the workpiece 26 to generate a plasma 30 between the electrode portion 33 and the surface of the workpiece 26, The plasma 30 is brought into contact with the surface of the workpiece 26.

  As a result, active species generated by the plasma 30 act on the surface of the workpiece 36 to generate a compound, and the compound vaporizes and diffuses in the gas phase, thereby advancing the processing of the workpiece 26. .

  According to the plasma processing apparatus of the first embodiment, the distance between the electrode part 33 and the substrate stage 24 can be freely adjusted, and the opposing surface 34 of the electrode part 33 is arranged at one end and the central part from the central part. Therefore, the gas can be efficiently supplied to a narrow space between the electrode portion 33 and the workpiece 26 and the radial direction of the rotating shaft 23 can be increased. The non-uniformity of the plasma contact time of the workpiece 26 depending on the position can be eliminated. Therefore, a plurality of workpieces having a large surface area can be uniformly and efficiently processed with a simple configuration.

  Further, according to the plasma processing apparatus of the first embodiment, since atmospheric pressure plasma generated under atmospheric pressure or pressure near atmospheric pressure is used, neutral radicals that contribute to the processing of the workpiece 26 are obtained. The absolute number can be increased, and the chemical reaction between the neutral radical and the atoms constituting the workpiece 26 can be promoted. Therefore, the processing speed of the workpiece 26 can be increased.

  In addition, since there are a large number of atoms and molecules in the atmospheric pressure plasma, ions in the atmospheric pressure plasma collide with some kind of atoms and molecules before reaching the surface of the workpiece 26, and the atmospheric pressure plasma. The ions inside do not reach the surface of the workpiece 26 directly. Therefore, since the surface of the workpiece 26 is not damaged during processing, the crystallinity of the surface of the workpiece 26 can be improved.

  Furthermore, since atmospheric pressure plasma generated under atmospheric pressure or near atmospheric pressure is used, a reaction vessel having a strength required to form a low-pressure atmosphere, a powerful exhaust system, etc. Never needed. Therefore, the manufacturing cost of the apparatus can be reduced, and the manufacturing cost of the final product can be reduced.

  In the plasma processing apparatus according to the first embodiment, the facing surface 34 of the electrode portion 33 has a fan-like shape whose width decreases linearly from one end of the electrode portion 33 directly below the rotating shaft 23. 1 region 37 and a second region 38 having a fan-like shape whose width decreases linearly from the other end of the electrode portion 33 directly below the rotating shaft 23, and the center line of the first region 37; The center line of the second region 38 is located on substantially the same straight line, and the center angle of the first region 37 and the center angle of the second region 38 are the same angle. However, according to the present invention, the central angle of the fan-shaped first region and the central angle of the fan-shaped second region are the same as the central angle of the first region and the central angle of the second region. For example, as shown in FIG. 4 corresponding to FIG. 3C in the plasma processing apparatus of the modification of the first embodiment, the central angle α shown in FIG. In comparison, a larger central angle α ′ may be employed.

  The central angle of the fan-shaped first region and the central angle of the fan-shaped second region having the same value can be arbitrarily selected, and may be any of acute angle, right angle, and obtuse angle. In each specification, the central angle of the fan-shaped region may be set to an angle at which the plasma contact time of the workpiece can be made approximately equal when the plasma processing apparatus is operated and the rotating electrode is rotated.

  Further, in the first embodiment, the circumferential length of the facing surface 34 in the radially inner region from the radially outermost portion of the rotating shaft 23 in the facing surface 34 is as follows. Although it increased in a linear function as it went outward in the radial direction (although it increased in proportion to the position in the radial direction), in the present invention, the radial direction of the rotating shaft on the opposing surface of the electrode portion In the radially inner region from the outermost portion, the circumferential length of the rotating shaft of the facing surface is higher-order function (for example, as it goes outward in the radial direction) It may be larger (in proportion to the square of the radial position (coordinates)).

(Second Embodiment)
FIG. 5A is a view corresponding to FIG. 3B in the plasma processing apparatus of the second embodiment of the present invention, and is a perspective view showing the periphery of the rotating electrode 52 of the plasma processing apparatus of the second embodiment of the present invention. FIG. 5B is a diagram corresponding to FIG. 3C in the plasma processing apparatus of the second embodiment, and is a schematic plan view of the rotating electrode 52 as viewed from the workpiece 26 side.

  In the plasma processing apparatus according to the second embodiment, the opposing surface 64 on the substrate stage 24 side of the electrode portion 33 is different only in that the opposing surface 64 on the substrate stage 24 side of the electrode portion 53 is composed of four fan-shaped regions. This is different from the plasma processing apparatus according to the first embodiment, which includes two fan-shaped regions 37 and 38.

  In the plasma processing apparatus of the second embodiment, the same components as those of the plasma processing apparatus of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. Further, in the plasma processing apparatus of the second embodiment, the description of the operations and effects common to the plasma processing apparatus of the first embodiment will be omitted, and the configuration and operation different from those of the plasma processing apparatus of the first embodiment will be omitted. Only the effect will be described.

  As shown in FIG. 5A, the rotating electrode 52 of the plasma apparatus of the second embodiment includes an electrode portion 53 and a rotating shaft 63, and one end of the rotating shaft 63 is on the opposite side of the electrode portion 53 from the substrate stage 24 side. Connected to the center of the surface. The rotation shaft 63 extends substantially perpendicular to the placement surface 66 of the substrate stage 24.

  The electrode portion 53 has a cross shape and has four end portions. The opposing surface 64 of the electrode portion 33 on the substrate stage 24 side has an electrode width that decreases from the first end portion of the electrode portion 53 directly below the rotation shaft 63 and rotates from the second end portion of the electrode portion 53. The electrode width becomes narrower directly below the shaft 63. In addition, the facing surface 64 has an electrode width that decreases from the third end of the electrode portion 53 directly below the rotation shaft 63, and extends from the fourth end of the electrode portion 53 directly below the rotation shaft 63. The electrode width is narrow.

  As shown in FIG. 5B, the opposing surface 64 on the substrate stage 24 side of the electrode portion 53 includes a fan-shaped first region 70 whose width decreases from the first end of the electrode portion 53 directly below the rotation shaft 63, and the electrode A fan-shaped second region 71 whose width decreases from the second end of the portion 53 toward directly below the rotation shaft 63, and a fan-shaped second region 71 whose width decreases from the third end of the electrode portion 53 directly below the rotation shaft 63. 3 regions 72 and a fan-shaped fourth region 73 whose width decreases from the fourth end of the electrode portion 53 directly below the rotation shaft 63.

  The center line (bisector) of the first region 70 and the center line (bisector) of the third region 72 are located on substantially the same straight line (referred to as the first straight line), The center line (bisector) of the second region 71 and the center line (bisector) of the fourth region 73 are located on substantially the same straight line (referred to as a second straight line). The central angles of the first to fourth regions 70, 71, 72, 73 are all the same. The first straight line and the second straight line are orthogonal to each other.

  According to the plasma processing apparatus of the second embodiment, since the number of fan-shaped regions 70, 71, 72, 73 of the electrode portion 53 is larger than that of the first embodiment, the area of the facing surface 64 is increased. And the electric field generation region can be increased.

  In the present invention, the number of fan-shaped regions may be any number, and there is no restriction on the central angle of the fan-shaped regions. However, when the number of fan-shaped regions increases or when the central angle of the fan-shaped regions increases, the supply of fresh reaction gas to the region immediately below the rotation axis of the rotating electrode is not possible. There is a high possibility of being disturbed. For this reason, it is preferable that the number of fan-shaped regions is small, and the central angle of each fan-shaped region is set to be small.

(Third embodiment)
FIG. 6 is a view corresponding to FIG. 3B in the plasma processing apparatus of the third embodiment of the present invention, and is a perspective view showing a peripheral portion of the rotating electrode 22 of the plasma processing apparatus of the third embodiment of the present invention.

  The plasma processing apparatus of the third embodiment is different from the plasma processing apparatus of the first embodiment only in that it has a rotating device that rotates the workpiece.

  In the plasma processing apparatus of the third embodiment, the same components as those of the plasma processing apparatus of the first embodiment are denoted by the same reference numerals and description thereof is omitted. Further, in the plasma processing apparatus of the third embodiment, the description of the operations and effects common to the plasma processing apparatus of the first embodiment will be omitted, and the configuration and operation different from those of the plasma processing apparatus of the first embodiment will be omitted. Only the effect will be described.

  The rotating device includes a vacuum chuck (not shown) and a rotating mechanism (not shown) for rotating the vacuum chuck. The vacuum chuck is configured to hold a workpiece positioned on a workpiece holding position that exists at predetermined intervals in the circumferential direction on the mounting surface 31 of the substrate stage 24. Further, the rotation mechanism rotates the workpiece held by the vacuum chuck in the direction indicated by the arrow d in FIG. 6 by rotating the vacuum chuck holding the workpiece.

  According to the plasma processing apparatus of the third embodiment, since the workpiece 26 can be rotated, the workpiece 26 can be processed even more uniformly.

(Fourth embodiment)
FIG. 7A is a view corresponding to FIG. 3B in the plasma processing apparatus of the fourth embodiment of the present invention, and is a perspective view showing a peripheral portion of the rotating electrode 82 of the plasma processing apparatus of the fourth embodiment of the present invention.

  In the plasma processing apparatus of the fourth embodiment, the same components as those of the plasma processing apparatus of the first embodiment are denoted by the same reference numerals, and description thereof is omitted. In the plasma processing apparatus of the fourth embodiment, the description of the operation and effect common to the plasma processing apparatus of the first embodiment will be omitted, and the configuration and operation different from those of the plasma processing apparatus of the first embodiment will be omitted. Only the effect will be described.

  In the fourth embodiment, the rotating electrode 82 includes an electrode portion 83 and a rotating shaft 84. The rotation shaft 84 extends in the normal direction of the placement surface 31 of the workpiece 26 of the substrate stage 24. The electrode portion 83 has a plate-like base portion 85 and a plurality of needle-like protrusion portions 86 as protrusions. A plurality of workpieces 26 are arranged radially about the rotation shaft 84. While the base 85 has a prismatic shape, each needle-like protrusion 86 protrudes toward the substrate stage 24 from the surface of the base 85 on the substrate stage 24 side. The mounting surface 31 of the substrate stage 24 and the surface of the base 85 on the substrate stage 24 side are substantially parallel. Each needle-like protrusion 86 extends in the normal direction of the surface of the base 85 on the substrate stage 24 side.

  In a state in which the workpiece 26 is held at a predetermined position, the facing surface that faces the workpiece 26 in the axial direction of the rotation shaft 84 and extends substantially perpendicular to the axial direction is formed on each needle-like protrusion 86. It is composed of a combination of surfaces opposite to the base 85.

  FIG. 7B is a schematic plan view of the electrode unit 83 viewed from the substrate stage 24 side.

  The surface of the base 85 on the substrate stage 24 side has a substantially rectangular shape. The density per unit area of the needle-like protrusions 86 increases as the distance increases from the surface that bisects the length in the longitudinal direction of the surface of the base 85 on the substrate stage 24 side. Precisely, the density of the needle-like projections 86 increases in proportion to the distance from the bisecting surface.

  According to the plasma processing apparatus of the fourth embodiment, the density of the needle-like protrusions 86 increases as the distance from the bisecting surface increases. When the electrode 82 is rotated, the plasma contact time of the workpiece 26 can be made substantially equal regardless of the radial position, and the workpiece surface of the workpiece 26 can be processed uniformly.

  In the plasma processing apparatus of the fourth embodiment, the width of the surface of the base portion 85 on the substrate stage 24 side is the same. However, in the present invention, in the case where the electrode portion has a structure having a base portion and a protrusion. However, as in the first embodiment, the width of the base may be increased in proportion to the distance from the line that bisects the length in the longitudinal direction of the surface of the base on the substrate stage side, In this case, the processed surface of the workpiece can be processed more uniformly, which is preferable.

(Fifth embodiment)
FIG. 8A is a view corresponding to FIG. 3B in the plasma processing apparatus of the fifth embodiment of the present invention, and is a perspective view showing a peripheral portion of the rotating electrode 92 of the plasma processing apparatus of the fifth embodiment of the present invention.

  In the plasma processing apparatus of the fifth embodiment, the same components as those of the plasma processing apparatus of the first embodiment are denoted by the same reference numerals, and description thereof is omitted. Further, in the plasma processing apparatus of the fifth embodiment, the description of the operations and effects common to the plasma processing apparatus of the first embodiment will be omitted, and the configuration and operation different from those of the plasma processing apparatus of the first embodiment will be omitted. Only the effect will be described.

  In the fifth embodiment, the rotating electrode has an electrode portion and a rotating shaft. The rotating shaft 3 extends in the normal direction of the mounting surface of the workpiece of the substrate stage.

  In the fifth embodiment, the electrode portion 93 of the rotating electrode 92 has a prismatic shape. A plurality of holes 97 are formed in the electrode portion 93. The mounting surface 31 of the workpiece 26 of the substrate stage 24 and the facing surface of the electrode portion 93 on the substrate stage 24 side are substantially parallel. The extending direction of each hole 97 is substantially equal to the normal direction of the surface of the electrode portion 93 on the substrate stage 24 side.

  FIG. 8B is a schematic plan view of the electrode portion 93 viewed from the substrate stage 24 side.

  As shown in FIGS. 8A and 8B, the air hole 97 that overlaps the rotation axis 103 in the normal direction has a bottom, but does not overlap the rotation axis 103 in the normal direction. The hole has no bottom and is a through hole that penetrates the electrode portion 93. All the holes 97 are opened on the opposing surface of the electrode portion 93 on the substrate stage 24 side. When the rotating electrode 92 rotates, the density per unit area of the holes 97 is separated from the rotating shaft 103 so that the plasma contact time of the workpiece 26 becomes equal regardless of the radial position of the rotating shaft 103. It is decreasing according to. Specifically, the density of the holes 97 is set so as to decrease in proportion to the distance from the rotation shaft 103.

(Sixth embodiment)
FIG. 9A is a view corresponding to FIG. 5A in the plasma processing apparatus of the sixth embodiment of the present invention, and is a perspective view showing the periphery of the rotating electrode 252 of the plasma processing apparatus of the sixth embodiment of the present invention.

  In the plasma processing apparatus of the sixth embodiment, the description of the common configuration, operation effects, and modifications of the plasma processing apparatus of the second embodiment will be omitted, and the configuration and operation different from those of the plasma processing apparatus of the second embodiment will be omitted. Only the effects and modifications will be described.

  As shown in FIG. 9A, in the plasma processing apparatus of the sixth embodiment, the opposing surface 264 of the electrode unit 253 on the substrate stage 224 side is configured from four fan-shaped regions, as in the second embodiment. In the plasma processing apparatus of the sixth embodiment, a motor (not shown) that rotates the rotating shaft 263 is a reversible motor, and the rotating shaft 263 can be rotated in both directions by the motor. Yes.

  9B is a cross-sectional view in the circumferential direction showing the cross section when the electrode portion 253 is cut along the virtual cylindrical surface Z having the central axis of the rotation shaft 263 as the central axis in FIG. 9A. It is a schematic cross section which shows the direction of the flow of the airflow at the time of rotating to the direction shown by.

  In FIG. 9B, the arrow X is the rotation direction when the electrode unit 253 rotates with respect to the substrate stage 224. The direction indicated by the arrow X is the first direction. The reference number 280 passes through the front edge 275 (see FIGS. 9A and 9B) of the rotation in the X direction on the surface 290 of the electrode portion 253 on the rotating shaft 263 side, and is the method of the mounting surface 266 of the substrate stage 224. A plane extending in the line direction is shown.

  As shown in FIG. 9B, in the circumferential sectional view, the electrode portion 253 has a parallelogram sectional shape, and the two sides of the parallelogram are substantially parallel to the mounting surface 266 of the substrate stage 224. It has become. In the cross-sectional view of FIG. 9B, the distance between the end surface 270 on the front side of the rotation of the electrode section 253 and the plane 280 (more precisely, the distance in the direction parallel to the mounting surface 266 of the substrate stage 224) is the substrate stage 224. As the distance from the rotation axis 263 side toward the substrate stage 224 side in the normal direction of the mounting surface 266 increases, it increases in a linear function.

  9B, when the electrode portion 253 rotates in the direction indicated by the arrow X, the distance between the front end surface 270 of the rotation of the electrode portion 253 and the plane 280 is the normal direction of the plane stage 224 from the rotation axis 263 side. Since it increases in a linear function as it goes to the substrate stage 224 side, the gas that collides with the end surface 270 receives a force on the substrate stage 224 side due to the component force of the normal force of the end surface 270. Therefore, as indicated by an arrow P in FIG. 9B, the gas colliding with the end surface 270 is guided by the end surface 270 and is moved along the end surface 270 from the rotary shaft 263 side to the substrate stage 224 side. It will move smoothly to 224.

  Therefore, since the gas can be forcibly supplied to the reaction region, the processing efficiency can be improved. In addition, since a large flow of gas flowing between the facing surface 164 and the substrate stage 224 can be generated, gas agitation can be promoted inside the plasma processing apparatus, and gas mixing uniformity can be improved. Can be increased.

  FIG. 9C is a circumferential cross-sectional view showing a cross section when the electrode portion 253 is cut along the virtual cylindrical surface Z having the central axis of the rotation shaft 263 as the central axis in FIG. 9A. It is a schematic cross section which shows the direction of the flow of the airflow at the time of rotating to the direction shown by.

  In FIG. 9C, the arrow Y indicates the rotation direction when the electrode unit 253 rotates with respect to the substrate stage 224. The direction indicated by the arrow Y is the second direction. The direction indicated by the arrow Y is opposite to the direction indicated by the arrow X.

  In FIG. 9C, reference numeral 380 denotes a plane that passes through the front edge 375 (see FIGS. 9A and 9C) of the counter surface 264 in the Y direction and extends in the normal direction of the mounting surface 266 of the substrate stage 224. Show.

  In the cross-sectional view of FIG. 9C, the distance between the end surface 370 on the front side of the rotation of the electrode portion 253 and the plane 380 (more precisely, the distance in the direction parallel to the mounting surface 266 of the substrate stage 224) is the substrate stage 224. The height increases in a linear function from the substrate stage 224 side to the rotating shaft 263 side in the normal direction of the mounting surface 266.

  In FIG. 9C, when the electrode portion 253 rotates in the direction indicated by the arrow Y, the distance between the end surface 370 on the front side of the rotation of the electrode portion 253 and the plane 380 is the normal direction of the plane stage 224 from the substrate stage 224 side. The gas that collides with the end surface 270 receives the force on the rotating shaft 263 side due to the component of the normal force of the end surface 270 because it increases in a linear function as it goes to the rotating shaft 263 side. Therefore, as indicated by an arrow Q in FIG. 9C, the gas colliding with the end surface 370 is guided by the end surface 370 and is rotated along the end surface 370 from the substrate stage 224 side to the rotation shaft 263 side. The surface 290 on the side is smoothly moved to a region opposite to the substrate stage 224 side.

  Therefore, the gas can be forcibly discharged from the plasma part 230 as the reaction region, and the reaction product can be prevented from remaining on the surface of the workpiece 226. Moreover, stirring of the gas inside the apparatus can be promoted, and the mixing uniformity of the gas can be improved.

  According to the plasma processing apparatus of the sixth embodiment, by setting the rotation direction of the electrode unit 253 to the X direction, an air flow from the rotation shaft 263 side to the substrate stage 224 side can be generated, while the rotation of the electrode unit 253 is performed. By setting the direction to the Y direction, an airflow from the substrate stage 224 side to the rotating shaft 263 side can be generated.

  The plasma processing apparatus according to the sixth embodiment exhibits its capability in, for example, a process in which the surface of the workpiece 226 is subjected to a plasma oxidation process as a pretreatment, and an oxide film is subjected to a plasma etching process as a posttreatment.

  That is, in the pretreatment, since it is desirable to supply a large amount of oxidizing species to the surface to be processed of the workpiece 226, the electrode portion 253 is rotated in the direction of the arrow X shown in FIG. A gas flow from the substrate stage 224 to the substrate stage 224 is generated so that many oxidizing species are supplied to the workpiece surface of the workpiece 226. In this way, the processing speed is increased.

  On the other hand, in post-processing, in order to suppress the reaction product due to the etching reaction from remaining on the surface of the workpiece, the electrode portion 253 is rotated in the direction of arrow Y shown in FIG. A gas flow toward the rotating shaft 263 is generated. In this way, the reaction product is forcibly discharged from the workpiece surface and the plasma part 230 to reduce the amount of residue adhering to the workpiece surface of the workpiece 226, and at the same time, plasma that is a reaction region. The portion 230 is prevented from being soiled by the residue.

  According to the plasma processing apparatus of the sixth embodiment, since the motor that rotates the rotating shaft 263 is a reversible motor, the pretreatment and the posttreatment are performed at any time without replacing the rotating electrode 252. It can be performed continuously just by supplying.

  In the plasma processing apparatus of the sixth embodiment, the circumferential section of the electrode portion 253 has a parallelogram shape. However, in the present invention, the electrode portion may have convex end surfaces on both sides in the circumferential direction of the electrode portion, and the sectional shape in the circumferential direction of the electrode portion is a parallelogram as shown in FIG. Only the straight line in the front-rear direction of the parallelogram may be replaced with a curve that protrudes outward in the circumferential direction. The cross section in the circumferential direction of the electrode part can generate both a gas flow from the rotation axis side to the substrate stage side and a gas flow from the substrate stage side to the rotation axis side by changing the rotation direction of the electrode part. Any shape may be used as long as it has such a shape.

  Needless to say, the present invention is not limited to the first to sixth embodiments, and the present invention includes a plasma processing apparatus within the scope of the claims and within the scope equivalent to the scope of the claims. Needless to say.

It is a typical side perspective view of the processing apparatus made as an experiment. It is the schematic of the electrode peripheral part of the processing apparatus shown to FIG. 1A. It is a figure which shows an example of the cross-sectional profile of the process trace obtained when processing the silicon substrate with the plasma processing apparatus shown to FIG. 1A. It is a typical side perspective view of the plasma processing apparatus of a 1st embodiment of the present invention. FIG. 3B is a schematic perspective view showing a part of the apparatus shown in FIG. 3A, and a perspective view showing the periphery of the rotating electrode. It is the model top view which looked at the rotating electrode shown to FIG. 3B from the workpiece side. It is a figure corresponding to FIG. 3C of the plasma processing apparatus of the modification of 1st Embodiment. It is a figure corresponding to FIG. 3B in the plasma processing apparatus of 2nd Embodiment of this invention, and is a perspective view which shows the peripheral part of the rotating electrode of the plasma processing apparatus of 2nd Embodiment of this invention. It is a figure corresponding to FIG. 3C in the plasma processing apparatus of 2nd Embodiment, and is the schematic top view which looked at the rotating electrode from the to-be-processed side. It is a figure corresponding to FIG. 3B in the plasma processing apparatus of 3rd Embodiment of this invention, and is a perspective view which shows the peripheral part of the rotating electrode of the plasma processing apparatus of 3rd Embodiment of this invention. It is a figure corresponding to FIG. 3B in the plasma processing apparatus of 4th Embodiment of this invention, and is a perspective view which shows the peripheral part of the rotating electrode of the plasma processing apparatus of 4th Embodiment of this invention. It is the model top view which looked at the electrode part of the plasma processing apparatus of 4th Embodiment from the substrate stage side. It is a figure corresponding to FIG. 3B in the plasma processing apparatus of 5th Embodiment of this invention, and is a perspective view which shows the peripheral part of the rotating electrode of the plasma processing apparatus of 5th Embodiment of this invention. It is the model top view which looked at the electrode part of the plasma processing apparatus of 5th Embodiment from the substrate stage side. It is a figure corresponding to FIG. 5A in the plasma processing apparatus of 6th Embodiment of this invention, and is a perspective view which shows the peripheral part of the rotating electrode of the plasma processing apparatus of 6th Embodiment of this invention. 9A is a circumferential cross-sectional view showing a cross section when the electrode portion is cut by a virtual cylindrical surface having the central axis of the rotation axis as the central axis, and when the electrode portion is rotated in the direction indicated by the arrow X. FIG. It is a schematic cross section which shows the direction of the flow of airflow. 9A is a sectional view in the circumferential direction showing a cross section when the electrode portion is cut by a virtual cylindrical surface having the central axis of the rotation axis as the central axis, and the electrode portion is an arrow in the direction opposite to the arrow X described above. It is a schematic cross section which shows the direction of the flow of the airflow at the time of rotating to the direction shown by Y. It is a schematic cross section of the circumferential direction of the electrode part of the plasma processing apparatus of a modification.

Explanation of symbols

21 Reaction vessel 22,252 Rotating electrode 23,263 Rotating shaft 24,224 Substrate stage 25 Heater 26,226 Workpiece 27 High frequency power supply 28 Gas introduction line 29 Gas exhaust line 30 Plasma 31 Mounting surface 34,264 Opposing surface 37 First 1 region 38 2nd region 86 acicular protrusion 97 hole 230 plasma portion 253 electrode portion 266 placement surface X rotation direction Y rotation direction P gas flow generated by rotation direction X Q gas flow generated by rotation direction Y

Claims (8)

A workpiece holding section for holding the workpiece in a predetermined position;
In a state where the rotary shaft and the workpiece are held at the predetermined position, the workpiece has an opposing surface that faces the axial direction of the rotary shaft and extends substantially perpendicular to the axial direction. And a rotating electrode having an electrode portion connected to one end of the rotating shaft,
In the region inward of the radial direction with respect to the radially outermost portion of the rotating shaft on the facing surface, the circumferential length of the rotating shaft of the facing surface is outside the radial direction. A plasma processing apparatus characterized by becoming larger as it goes. The plasma processing apparatus according to claim 1, wherein
The plasma processing apparatus according to claim 1, wherein the facing surface is composed of a plurality of regions whose width in the circumferential direction increases toward the outside in the radial direction. In the plasma processing apparatus according to claim 1 or 2,
When the electrode portion is rotated in one direction with respect to the work holder, the end surface on the front side of the rotation of the electrode portion holds the gas in contact with the end surface at the predetermined position with the facing surface. A plasma processing apparatus having a shape that promotes movement between the workpiece and the workpiece. In the plasma processing apparatus according to claim 1 or 2,
In the case where the electrode unit is rotating in one direction with respect to the workpiece holding unit, the end surface on the front side of the rotation of the electrode unit has a gas in contact with the end surface on the rotating shaft side of the electrode unit. A plasma processing apparatus having a shape that promotes movement. In the plasma processing apparatus according to claim 1 or 2,
When the electrode portion is rotating in the first direction with respect to the workpiece holding portion, the end surface on the front side of the rotation of the electrode portion is such that the gas contacting the end surface is in contact with the facing surface and the predetermined position. The electrode portion is in a second direction opposite to the first direction with respect to the workpiece holding portion, while the shape promotes movement between the workpiece holding portion and the workpiece holding portion. In the case of rotation, the plasma processing is characterized in that the end surface on the front side of the rotation of the electrode portion has a shape that promotes the movement of the gas in contact with the end surface toward the rotation shaft side of the electrode portion. apparatus. The plasma processing apparatus according to claim 1, wherein
The electrode part has a plate-like base and a plurality of protrusions protruding from the base,
The plasma processing apparatus, wherein the facing surface is a combination of the surfaces of the protrusions opposite to the base. The plasma processing apparatus according to claim 1, wherein
A plurality of holes open on the facing surface,
The plasma processing apparatus according to claim 1, wherein the density per unit area of the pores decreases as going outward in the radial direction. In the plasma processing apparatus according to any one of claims 1 to 7,
The workpiece holding unit has a plurality of workpiece holding positions for holding the workpiece at predetermined intervals in the circumferential direction,
A plasma processing apparatus comprising: a rotation device that rotates the workpiece held at the workpiece holding position.

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