JP5324975B2 - Plasma processing equipment - Google Patents

Description

  The present invention relates to a plasma processing apparatus such as a dry etching apparatus and a plasma CVD apparatus.

  In Patent Document 1, a tray that accommodates a substrate in a substrate accommodation hole penetrating in the thickness direction is disposed on a substrate susceptor that functions as a lower electrode, and the substrate placement of the substrate susceptor that has entered the substrate accommodation hole. A plasma processing apparatus having a configuration in which a substrate is placed on the upper end surface (substrate placement surface) of the part is disclosed. The substrate is brought into close contact with the substrate mounting surface by electrostatic adsorption. The substrate susceptor is provided with a cooling mechanism, and the substrate is cooled by direct heat conduction with the substrate susceptor.

  However, in the plasma processing apparatus described in Patent Document 1, since the substrate mounting surface is a substantially flat surface, when the substrate has an upward convex warp, the lower surface of the substrate and the substrate mounting surface A gap is generated between them, and the degree of adhesion of the substrate to the substrate susceptor decreases. For example, when a GaN layer formed on a 3-inch sapphire substrate is dry-etched, a gap of 100 μm or more is generated between the lower surface of the substrate and the substrate mounting surface in the central region of the substrate due to warpage of the substrate. This decrease in the degree of adhesion causes a decrease in the cooling efficiency of the substrate. If the cooling efficiency is low, the etching rate cannot be improved using high-frequency power. In order to increase the brightness of the LED, a laminated film having an MQW (Multiple Quantum Wells) structure or the like is used for the light emitting layer in which the gallium nitride Pn junction type semiconductor and the metal electrode are laminated. The warpage of the substrate is further increased. Further, for high productivity, as the substrate size increases from 2 inches to 3 inches, 4 inches, and 6 inches, warpage increases. In order to suppress warpage, there are methods such as optimizing the conditions of a film forming apparatus such as MOCVD and increasing the thickness of the sapphire substrate. The former is a trade-off with the formation of a high-brightness laminated film, and the latter is a substrate cost. Increase. Therefore, there is a need for a technique that can perform a highly efficient cooling process even on a warped substrate.

JP 2007-109770 A

  The present invention provides a plasma processing apparatus in which a tray that accommodates a substrate in a substrate accommodation hole is disposed on a substrate susceptor, thereby improving the cooling efficiency of the substrate by holding the substrate with a high degree of adhesion to the substrate susceptor. Let it be an issue.

The present invention is provided with a chamber capable of depressurization, a plasma generation source for generating plasma in the chamber, and a substrate accommodation hole penetrating in the thickness direction, protruding from a hole wall of the substrate accommodation hole, A substrate support portion that supports an outer peripheral edge portion of the lower surface of the substrate accommodated in the tray, a tray that can be carried into and out of the chamber, and the substrate that is provided in the chamber and carried into the chamber is accommodated. A tray support portion that supports the lower surface of the tray, and protrudes upward from the tray support portion, is inserted into the substrate receiving hole from the lower surface side of the tray, and is placed on the substrate placement surface that is the upper end surface of the lower surface of the substrate A substrate mounting portion on which the substrate mounting surface is a curved surface convex upward, and a dielectric member and at least a part of the substrate mounting portion is incorporated in the substrate mounting portion. Above An electrostatic chucking electrode for electrostatic chucking on the plate mounting surface; a DC voltage applying mechanism for applying a DC voltage to the electrostatic chucking electrode; and a space between the substrate and the substrate mounting surface. A heat transfer gas supply mechanism for supplying a heat transfer gas , and the substrate is a substrate obtained by epitaxially growing a GaN layer on a sapphire substrate, and has a warp generated during the epitaxial growth. A plasma processing apparatus is provided, wherein a curvature of a surface is smaller than a curvature of warpage of the substrate .

  Since the substrate placement surface is an upwardly convex curved surface, the degree of adhesion between the lower surface of the substrate where the substrate is warped and the substrate placement surface is high. Since the adhesion between the lower surface of the substrate and the substrate mounting surface is high, the electrostatic adsorption force for adsorbing the substrate to the substrate mounting surface is strong, and the substrate via the heat transfer gas supplied from the heat transfer gas supply mechanism The thermal conductivity between the substrate and the substrate mounting surface is good, and the substrate can be cooled with high efficiency. Since the substrate can be cooled with high efficiency, the plasma processing efficiency can be improved by supplying high-frequency power to the plasma generation source.

  Preferably, the electrode for electrostatic attraction is a curved surface along the substrate placement surface. As an alternative, the electrode for electrostatic attraction includes a plurality of portions arranged along the substrate placement surface.

  With these configurations, the electrostatic adsorption force acting on the substrate placed on the substrate placement surface can be made uniform, and as a result, the cooling efficiency of the substrate can be further improved.

  The distance from the lower surface of the tray to the upper surface of the substrate support portion is such that the lower surface of the substrate placed on the substrate placement surface is separated from the substrate support portion of the tray by a predetermined amount. Is set to be shorter than the distance from the substrate mounting surface.

  With this configuration, when the lower surface of the tray is placed on the tray support portion, the substrate pushed up by the substrate placement surface is lifted from the substrate support portion.

  Preferably, a plurality of the substrate accommodation holes are provided in the tray, the dielectric member includes a plurality of the substrate placement portions, and each of the substrate placement portions is inserted into each of the substrate accommodation holes.

  For example, the substrate is a substrate obtained by epitaxially growing a GaN layer on a sapphire substrate, and the warpage of the substrate is caused during the epitaxial growth.

  In the plasma processing apparatus of the present invention, the lower surface of the substrate is placed on the substrate placement surface which is the upper end surface of the substrate placement portion inserted into the substrate accommodation hole from the lower surface side of the tray, and the substrate placement surface faces upward. It is a convex curved surface. Therefore, the degree of adhesion between the lower surface of the substrate warped in a convex shape and the substrate mounting surface is high, the substrate can be attracted to the substrate mounting surface with a strong electrostatic adsorption force, and the substrate can be cooled with high efficiency. The plasma processing efficiency can be improved by supplying a high frequency power to the plasma generation source.

(First embodiment)
1 and 2 show an ICP (inductively coupled plasma) type dry etching apparatus 1 according to a first embodiment of the present invention.

  The dry etching apparatus 1 includes a depressurizable chamber (vacuum container) 3 that constitutes a processing chamber in which plasma processing is performed on the substrate 2. As will be described in detail later, the substrate 2 has an upwardly convex warp. The upper end opening of the chamber 3 is closed in a sealed state by a top plate 4 made of a dielectric material such as quartz. An ICP coil 5 is disposed on the top plate 4. A high frequency power source 7 is electrically connected to the ICP coil 5 via a matching circuit 6. A substrate susceptor 9 having a function as a lower electrode to which a bias voltage is applied and a function as a holding table for the substrate 2 is disposed on the bottom side in the chamber 3 facing the top plate 4. The chamber 3 is provided with a loading / unloading gate 3a that can be opened and closed and communicates with an adjacent load dock chamber 10 (see FIG. 2). An etching gas supply source 12 is connected to the etching gas supply port 3 b provided in the chamber 3. The etching gas supply source 12 includes an MFC (mass flow controller) or the like, and can supply an etching gas at a desired flow rate from the etching gas supply port 3b. Further, a vacuum exhaust device 13 including a vacuum pump or the like is connected to the exhaust port 3 c provided in the chamber 3.

  In this embodiment, four substrates 2 are accommodated in one tray 15 shown in FIGS. 3 to 4B, and the tray 15 is carried into the chamber 3 (processing chamber) from the load dock chamber 10 through the gate 3a. The Referring to FIG. 2, there is provided a transfer arm 16 that can move in a horizontal direction (see arrow A) and rotate in a horizontal plane (see arrow B). In the chamber 3, lift pins 18 that pass through the substrate susceptor 9 and are driven by a drive device 17 to move up and down are provided. When the tray 15 is carried in, the transfer arm 16 that supports the tray 15 enters the chamber 3 from the load dock chamber 10 through the gate 3a. At this time, as shown by a two-dot chain line in FIG. 1, the lifting pins 18 are in the raised position, and the tray 15 is transferred from the transfer arm 16 that has entered the chamber 3 to the upper end of the lifting pins 18. In this state, the tray 15 is positioned above the substrate susceptor 9 with a gap. Subsequently, the elevating pins 18 are lowered to the lowered position indicated by the solid line in FIG. 1, whereby the tray 15 and the substrate 2 are placed on the substrate susceptor 9. On the other hand, when the tray 15 is unloaded after the plasma processing, the elevating pins 18 are raised to the raised position, and then the tray 15 is transferred from the load dock chamber 10 to the transfer arm 16 that has entered the chamber 3.

Next, the tray 15 will be described with reference to FIGS. 3 to 4B and FIGS. 6A to 6C. The tray 15 includes a thin disc-shaped tray body 15a. Examples of the material of the tray 15 include ceramic materials such as alumina (Al ₂ O ₃ ), aluminum nitride (AlN), zirconia (ZrO), yttria (Y ₂ O ₃ ), silicon nitride (SiN), and silicon carbide (SiC). There are also metals such as aluminum coated with alumite, aluminum coated with ceramics on the surface, and aluminum coated with a resin material. It is conceivable to employ alumina, yttria, silicon carbide, aluminum nitride or the like in the case of a Cl-based process, and aluminum or the like which applies quartz, quartz, yttria, silicon carbide, anodized or the like in the case of an F-based process.

  The tray body 15a is provided with four substrate accommodation holes 19A to 19D that penetrate in the thickness direction from the upper surface 15b to the lower surface 15c. The substrate accommodation holes 19A to 19D are arranged at equiangular intervals with respect to the center of the tray body 15a when viewed from the upper surface 15b and the lower surface 15c. As most clearly shown in FIGS. 6A to 6C, a substrate support portion 21 that protrudes toward the center of the substrate accommodation holes 19 </ b> A to 19 </ b> D is provided on the lower surface 15 c side of the hole wall 15 d of the substrate accommodation holes 19 </ b> A to 19 </ b> D. ing. In this embodiment, the board | substrate support part 21 is provided in the perimeter of the hole wall 15d, and is annular | circular shape by planar view. You may provide the several board | substrate support part 21 arrange | positioned in the each board | substrate accommodation hole 19A-19D at intervals in the circumferential direction.

  One substrate 2 is accommodated in each of the substrate accommodation holes 19A to 19B. As shown in FIG. 6A, the outer peripheral edge portion of the lower surface 2 a of the substrate 2 accommodated in the substrate accommodating holes 19 </ b> A to 19 </ b> B is supported by the upper surface 21 a of the substrate support portion 21. Further, as described above, the substrate accommodation holes 19A to 19D are formed so as to penetrate the tray main body 15a in the thickness direction. Therefore, when viewed from the lower surface 15c side of the tray main body 15a, the substrate accommodation holes 19A to 19D allow the substrate 2 to pass through. The lower surface 2a is exposed.

  The tray body 15a is provided with a positioning cutout 15e in which the outer peripheral edge is partially cut out. As shown in FIG. 2, when the tray is placed on the carry-in / out carrying arm 16, the positioning protrusion 16a of the carrying arm 16 is fitted into the positioning notch 15e. By detecting the positioning notches 15e and the positioning protrusions 16a with the sensors 22A and 22B provided in the load dock chamber 10, the rotational angle position of the tray 15 can be detected.

  Next, the substrate susceptor 9 will be described with reference to FIGS. 1, 3, and 5A to 6C. First, referring to FIG. 1, the substrate susceptor 9 is made of a dielectric plate (dielectric member) 23 made of ceramics or the like, aluminum having an alumite coating on the surface, etc., and in this embodiment, a metal plate that functions as a pedestal electrode (Support member) 24, a spacer plate 25 made of ceramics or the like, a guide cylinder 26 made of ceramics or the like, and a metal earth shield 27 are provided. The dielectric plate 23 constituting the uppermost part of the substrate susceptor 9 is fixed to the upper surface of the metal plate 24. The metal plate 24 is fixed on the spacer plate 25. Further, the guide cylinder 26 covers the outer periphery of the dielectric plate 23 and the metal plate 24, and the earth shield 27 covers the outer periphery thereof and the outer periphery of the spacer plate 25.

  Referring to FIGS. 3 and 5A to 6C, the dielectric plate 23 has a thin disk shape as a whole, and has an outer shape in a plan view. The upper end surface of the dielectric plate 23 constitutes a tray support surface (tray support portion) 28 that supports the lower surface 15 c of the tray 15. Further, four short columnar substrate placement portions 29A to 29D respectively corresponding to the substrate accommodation holes 19A to 19D of the tray 15 protrude upward from the tray support surface 28.

  The upper end surfaces of the substrate placement portions 29A to 29D constitute a substrate placement surface 31 on which the lower surface 2a of the substrate 2 is placed. Further, the substrate placement portions 29 </ b> A to 29 </ b> D are provided with an annular protrusion 32 that protrudes upward from the outer peripheral edge of the substrate placement surface 31 and whose upper end surface supports the lower surface 2 a of the substrate 2. In addition, a plurality of columnar projections 33 having a sufficiently smaller diameter than the substrate mounting surface 31 are provided in a portion surrounded by the annular protrusion 32 of the substrate mounting surface 31 so as to be uniformly distributed. . Not only the annular protrusion 32 but also the upper end surface of the columnar protrusion 33 supports the lower surface 2 a of the substrate 2.

  Referring to FIG. 7, the substrate 2 has an upwardly convex warp, and as shown most clearly in FIG. 8, the substrate mounting surface 31 has an upwardly convex shape corresponding to the warp of the substrate 2. The curved surface. The substrate 2 has the largest amount of warpage Cw in the vicinity of the center 2b in plan view, and warps in a curved shape in which the amount of warpage gradually decreases from the central region 2c including the center 2b toward the outer peripheral region 2d including the outermost periphery. ing. As an example of the substrate 2 that generates such a warp, there is a substrate obtained by epitaxially growing GaN on a substrate made of sapphire for manufacturing an LED. In a manufacturing process in which GaN having a thickness of about 5 μm to 10 μm is epitaxially grown on a thin sapphire substrate having a thickness of about 300 μm to 600 μm, when the film is formed at a temperature of 600 ° C. to 1000 ° C. using, for example, MOCVD, the substrate (sapphire) and the film are formed. Due to the difference in the coefficient of linear expansion of the material (GaN), warpage occurs in the convex direction due to thermal expansion. In particular, in order to increase the brightness of an LED, a gallium nitride-based Pn junction semiconductor, a multilayer film having an MQW (Multiple Quantum Wells) structure or the like is used for a light emitting layer in which metal electrodes are stacked. The warpage of the substrate after filming is further increased. For example, the warpage may be about 100 μm on a 3 inch diameter GaN / sapphire substrate. Further, for the purpose of high productivity, as the substrate size is increased from 2 inches to 3 inches, 4 inches, and 6 inches, the warping amount Cw described above increases.

  Referring to FIG. 8, the substrate placement surface 31 has the highest height from the tray support surface 28 at the center 31b in plan view, and the outer peripheral edge region 31d (including the outermost peripheral edge from the central region 31c including the center 31b). A spherical curved surface in which the height from the tray support surface 28 gradually decreases toward the upper end surface of the annular protrusion 32. Therefore, the substrate mounting surface 31 is a curved surface having an upward convex shape in which the center 31b (included in the central region 31c) in plan view protrudes from the outermost peripheral edge (included in the outer peripheral region 31d) by the protrusion amount Cm. It is. The curvature of the substrate placement surface 31 is set smaller than the curvature of the warp of the substrate 2. In other words, the protrusion amount Cm of the substrate mounting surface 31 is set smaller than the warpage amount Cw of the substrate 2. Preferably, the substrate placement surface 31 is set so that the protrusion amount Cm is smaller than the warpage amount Cw of the substrate 2 and larger than half (1/2 Cw) of the warpage amount Cw of the substrate 2. For example, when the substrate 2 is a 3 inch sapphire substrate on which a GaN layer is formed, the warpage amount Cw of the substrate 2 is about 100 μm. In this case, the curvature of the substrate mounting surface 31 is set so that the protruding amount Cm is about 80 μm.

  Of the upper ends of the substrate placement portions 29A to 29D, the bottom wall 31a of the recess existing between the annular projection 32 and the columnar projection 33 is the substrate placement surface 31 (the annular projection 32 and the columnar projection 33). Of the upper end of the spherical surface of the same curvature. That is, the bottom wall 31 a is a curved surface parallel to the substrate placement surface 31. The depth of the recess (the amount of protrusion of the annular protrusion 32 and the columnar protrusion 33 from the bottom wall 31a) is set to be constant within a range of about 100 μm to 200 μm, for example. In this case, the height from the tray support surface 28 to the bottom wall 31a is set to about 1.0 mm to 2.0 mm.

  6A to 6C, the outer diameter R1 of the substrate placement portions 29A to 29D is set to be smaller than the diameter R2 of the circular opening 36 surrounded by the front end surface 21b of the substrate support portion 21. Accordingly, when the tray 15 is lowered toward the dielectric plate 23 at the time of carrying in, the individual substrate placement portions 29A to 29D enter the corresponding substrate accommodation holes 19A to 19D from the lower surface 15c side of the tray main body 15a, and the tray. The lower surface 15 c of 15 is placed on the tray support surface 28 of the dielectric plate 23. The height H1 of the upper surface 21a of the substrate support portion 21 from the lower surface 15c of the tray main body 15a is equal to the height H2 of the substrate placement surface 31 from the tray support surface 28 (both the central region 31c and the outer peripheral region 31d). It is set lower than (height). Therefore, in a state where the lower surface 15c of the tray 15 is placed on the tray support surface 28, the substrate 2 is pushed up by the substrate placement surface 31 at the upper end of the substrate placement portions 29A to 29D, and the substrate support portion 21 of the tray 15 is placed. From the surface. In other words, when the tray 15 accommodating the substrate 2 in the substrate accommodating holes 19A to 19D is placed on the tray support surface 28 of the dielectric plate 23, the lower surface of the substrate 2 accommodated in the substrate accommodating holes 19A to 19D. 2 a is lifted from the upper surface 21 a of the substrate support portion 21, separated upward by a predetermined amount (not in contact with the substrate support portion 21), and supported by the substrate placement surface 31. The outer peripheral edge portion of the substrate 2 supported by the substrate placement surface 31 faces the tray 15, specifically, the hole wall 15 d of the substrate accommodation holes 19 </ b> A to 19 </ b> D and the tip of the substrate placement portion 21. It is out.

  Referring to FIG. 1 and FIGS. 6A to 6C, a monopolar electrostatic attraction electrode 40 is built in the vicinity of the substrate placement surface 31 of each of the substrate placement portions 29A to 29D of the dielectric plate 23. . In the present embodiment, these electrostatic adsorption electrodes 40 have a flat plate shape. The electrostatic chucking electrodes 40 are electrically insulated from each other, and a DC voltage for electrostatic chucking is applied from a common DC voltage applying mechanism 43 including a DC power source 41 and an adjusting resistor 42. The electrode for electrostatic attraction may be a bipolar type. Moreover, you may provide one electrode for electrostatic attraction in common with substrate mounting part 29A-29D. The electrostatic adsorption electrode 40 is disposed at a depth of about 0.4 mm from the bottom wall 31a.

  Referring to FIGS. 3 and 5A to 6C, the substrate placement surfaces 31 of the individual substrate placement portions 29A to 29D are provided with supply holes 44 for heat transfer gas (helium in the present embodiment). These supply holes 44 are connected to a common heat transfer gas supply mechanism 45 (shown in FIG. 1). The heat transfer gas supply mechanism 45 includes a heat transfer gas source (in this embodiment, a helium gas source) 46, a supply channel 47 from the heat transfer gas source 46 to the supply hole 44, and a heat transfer gas source 46 in the supply channel 47. A flow meter 48, a flow control valve 49, and a pressure gauge 50 are provided in this order from the side. The heat transfer gas supply mechanism 45 includes a discharge flow channel 51 that branches from the supply flow channel 47 and a cut-off valve 52 provided in the discharge flow channel 51. Furthermore, the heat transfer gas supply mechanism 45 includes a bypass channel 53 that connects the supply channel 44 side to the discharge channel 51 with respect to the pressure gauge 50 of the supply channel 47. Between the substrate placement surface 31 of each of the substrate placement portions 29A to 29D and the lower surface 2a of the substrate 2 placed thereon, in detail, it is surrounded by the lower surface 2a of the substrate 2 and the annular protrusion 32. The heat transfer gas is supplied to the closed space by the heat transfer gas supply mechanism 45. When supplying the heat transfer gas, the cutoff valve 52 is closed, and the heat transfer gas is sent from the heat transfer gas supply source 46 to the supply hole 44 through the supply path 47. Based on the flow rate and pressure of the supply flow path 47 detected by the flow meter 48 and the pressure gauge 50, the controller 63 described later controls the flow rate control valve 49. On the other hand, when the heat transfer gas is discharged, the cut-off valve 52 is opened, and the heat transfer gas between the lower surface 2a of the substrate 2 and the substrate placement surface 31 passes through the supply hole 44, the supply flow path 47, and the discharge flow path 51. Then, the air is exhausted from the exhaust port 54.

  A high frequency applying mechanism 56 that applies a bias voltage, which is a high frequency voltage for generating plasma, is electrically connected to the metal plate 24. The high frequency applying mechanism 56 includes a high frequency power source 57 and a matching variable capacitor 58.

  Further, a cooling mechanism 59 for cooling the metal plate 24 is provided. The cooling mechanism 59 includes a refrigerant flow path 60 formed in the metal plate 24 and a refrigerant circulation device 61 that circulates the temperature-controlled refrigerant in the refrigerant flow path 60.

  The controller 63 schematically shown only in FIG. 1 is based on various sensors and operation inputs including a flow meter 48 and a pressure gauge 50, and a high-frequency power source 7, an etching gas supply source 12, a transfer arm 16, a vacuum exhaust device 13, The operation of the entire dry etching apparatus 1 including the drive device 17, the DC voltage application mechanism 43, the heat transfer gas supply mechanism 45, the high frequency voltage application mechanism 56, and the cooling mechanism 59 is controlled.

  Next, a dry etching method using the dry etching apparatus 1 of the present embodiment will be described.

  First, the board | substrate 2 is accommodated in the board | substrate accommodation holes 19A-19D of the tray 1, respectively. The substrate 2 supported by the substrate support portion 21a of the tray 1 is exposed from the lower surface 15c of the tray body 15a through the substrate housing holes 19A to 19D when viewed from the lower surface side of the tray body 15a.

  Next, the tray 15 that accommodates the substrate 2 in each of the substrate accommodation holes 19A to 19D is supported by the transfer arm 16, and is carried into the chamber 3 from the load dock chamber 10 through the gate 3a. As shown by a two-dot chain line in FIG. 1, the tray 1 is disposed above the substrate susceptor 9 with a gap.

  As shown in FIG. 6A, the lifting pins 18 driven by the driving device 17 are raised, and the tray 15 is transferred from the transfer arm 16 to the upper end of the lifting pins 18. After the transfer of the tray 15, the transfer arm 16 is retracted to the load lock chamber 10, and the gate 3a is closed.

  The raising / lowering pins 18 that support the tray 15 at the upper end are lowered toward the substrate susceptor 9 from the raised position indicated by a two-dot chain line in FIG. 6B and 6C, the lower surface 15c of the tray 15 descends to the tray support surface 28 of the dielectric plate 23 of the substrate susceptor 9, and the tray 15 is supported by the tray support surface 28 of the dielectric plate 23. When the tray 15 descends toward the tray support surface 28, the substrate placement portions 29A to 29D of the dielectric plate 23 enter the corresponding substrate accommodation holes 19A to 19D of the tray 15 from the lower surface 15c side of the tray 15. . As the lower surface 15c of the tray 15 approaches the tray support surface 28, the substrate placement surface 31 at the tip of the substrate placement portions 29A to 29D advances in the substrate accommodation holes 19A to 19D toward the upper surface 15b of the tray 15. As shown in FIG. 6C, when the lower surface 15c of the tray 15 is placed on the tray support surface 28 of the dielectric plate 23, the substrates 2 in the individual substrate accommodation holes 19A to 19D are moved by the substrate placement portions 29A to 29D. It is lifted from the upper surface 21 a of the substrate support portion 21. Specifically, the lower surface 2a of the substrate 2 is placed on the substrate placement surface 31 of the substrate placement portions 29A to 29D, and is disposed above the upper surface 21a of the substrate support portion 21 of the tray 15 with a gap. The

  As described above, the substrate placement portions 29A to 29D enter the substrate accommodation holes 19A to 19D of the tray 15, so that the substrate 2 is placed on the substrate placement surface 31. Accordingly, the four substrates 2 accommodated in the tray 15 are all placed on the substrate placement surfaces 31 of the substrate placement portions 29A to 29D with high positioning accuracy.

  Next, a DC voltage is applied from the DC voltage application mechanism 43 to the electrostatic attraction electrode 40 built in the dielectric plate 23, and the substrate 2 is applied to the substrate placement surfaces 31 of the individual substrate placement portions 29 </ b> A to 29 </ b> D. Is electrostatically adsorbed. The lower surface 2 a of the substrate 2 is directly placed on the substrate placement surface 31 without using the tray 15. Accordingly, the substrate 2 is held with a high degree of adhesion to the substrate placement surface 31.

  Subsequently, the heat transfer gas is supplied from the heat transfer gas supply device 45 through the supply hole 44 to the space surrounded by the annular protrusions 32 of the individual substrate placement portions 29 </ b> A to 29 </ b> D and the lower surface 2 a of the substrate 2. This space is filled with heat transfer gas.

  Thereafter, an etching gas is supplied from the etching gas supply source 12 into the chamber 3, and the inside of the chamber 3 is maintained at a predetermined pressure by the vacuum exhaust device 13. Subsequently, a high frequency voltage is applied from the high frequency power supply 7 to the ICP coil 5, and a bias voltage is applied to the metal plate 24 of the substrate susceptor 9 by the high frequency application mechanism 56 to generate plasma in the chamber 3. The substrate 2 is etched by this plasma. Since four substrates 2 can be placed on the substrate susceptor 9 with one tray 15, batch processing is possible.

  During the etching, the refrigerant is circulated in the refrigerant flow path 60 by the refrigerant circulation device 61 to cool the metal plate 24, thereby the substrate 2 held on the dielectric plate 23 and the substrate mounting surface 31 of the dielectric plate 23. Cool down. As described above, the lower surface 2a of the substrate 2 is directly placed on the substrate placement surface 31 without the tray 15 and is held with a high degree of adhesion. Therefore, the sealing degree of the space filled with the heat transfer gas surrounded by the annular protrusion 32 and the lower surface 2a of the substrate 2 is high, and the space between the substrate 2 and the substrate placement surface 31 through the heat transfer gas is high. Good thermal conductivity. As a result, since the substrate 2 held on the substrate placement surfaces 31 of the individual substrate placement portions 29A to 29D can be cooled with high cooling efficiency, high high-frequency power can be supplied to improve dry etching efficiency. Further, the temperature of the substrate 2 can be controlled with high accuracy. In addition, a heat transfer gas is filled in the space surrounded by the annular protrusion 32 and the lower surface 2a of the substrate placement portions 29A to 29D for each individual substrate 2. In other words, the space filled with the heat transfer gas is different for each substrate 2. Also in this respect, the thermal conductivity between the individual substrates 2 and the substrate mounting surface 31 of the dielectric plate 23 is good, and high cooling efficiency and high-accuracy temperature control can be realized.

  Moreover, although the board | substrate 2 has curvature, the board | substrate 2 can be cooled with high efficiency. Referring to FIG. 6C, as described above, the substrate placement surface 31 is formed as an upwardly convex curved surface, and the curvature of the substrate placement surface 31 is set to be smaller than the curvature of the warp of the substrate 2. The degree of adhesion between the lower surface of the substrate and the substrate placement surface 31 is high. Specifically, in the central region 2 c in plan view of the substrate 2, the gap δ generated between the lower surface of the substrate 2 and the substrate placement surface 31 due to the warp of the substrate 2 is minimized. Further, in the vicinity of the outer peripheral edge of the substrate 2, the state in which the lower surface of the substrate 2 is in close contact with the annular projecting portion 32 of the substrate mounting surface 31 with high adhesion by electrostatic adsorption is maintained. Since the degree of adhesion between the lower surface of the warped substrate 2 and the substrate placement surface 31 is high in this way, the substrate 2 and the substrate placement surface 31 via the heat transfer gas supplied from the heat transfer gas supply mechanism 45. The thermal conductivity between the two is good. In this respect as well, the substrate 2 can be cooled with high efficiency, and the high frequency power can be supplied to the plasma generation source to improve the dry etching efficiency and to achieve highly accurate temperature control.

  As described above, since the substrate 2 is directly placed on the substrate placement surfaces 31 of the individual substrate placement portions 29A to 29D and is electrostatically attracted, the degree of adhesion to the substrate placement surface 31 is high. Therefore, a member such as a clamp ring for mechanically pressing the outer peripheral edge portion of the upper surface of the substrate 2 against the dielectric plate 23 is unnecessary. In other words, there is no member on the upper surface of the substrate 2 that causes the plasma state to become unstable not only in the central portion but also in the vicinity of the outer periphery. Therefore, a uniform dry etching process can be realized in the entire region of the surface of the substrate 2 including the vicinity of the outer peripheral edge.

  After the etching is finished, the application of the high frequency voltage from the high frequency power source 7 to the ICP coil 5 and the application of the bias voltage from the high frequency application mechanism 56 to the metal plate 24 are stopped. Subsequently, the etching gas is exhausted from the chamber 3 by the vacuum exhaust device 13. Further, the heat transfer gas is exhausted from the substrate placement surface 31 and the lower surface 2 a of the substrate 2 by the heat transfer gas supply mechanism 45. Further, the application of the DC voltage from the DC voltage application mechanism 43 to the electrostatic chucking electrode 40 is stopped to release the electrostatic chucking of the substrate 2.

  Next, the elevating pins 18 are raised by the driving device 17. When the elevating pin 18 is raised, the lower surface 15c of the tray 15 is pushed up at the upper end of the elevating pin 18 and is lifted from the tray support surface 28 of the dielectric plate 23. When the toilet 15 is further lifted together with the lift pins 18, the lower surface 2c of the substrate 2 is pushed up by the substrate support portion 21 of the tray 15 as shown in FIG. 5A, and the substrate 2 is placed on the substrate placement surfaces of the substrate placement portions 29A to 29D. From 31 The raising / lowering pin 18 rises to a raised position indicated by a two-dot chain line in FIG.

  Thereafter, the tray 15 is transferred to the transfer arm 16 that has entered the chamber 3 from the load dock chamber 10 through the gate 3a. The tray 15 is carried out to the load dock chamber 10 by the transfer arm 16.

(Second Embodiment)
In the second embodiment of the present invention shown in FIGS. 9 and 10, the electrostatic attraction electrode 40 has a curved surface. Specifically, the electrostatic chucking electrode 40 has a curved surface shape along the substrate mounting surface 31 so that the distance from the substrate mounting surface 31 which is curved as described above is constant. For example, the shape of the electrostatic attraction electrode 40 is set so that the depth from the bottom wall 31a of the substrate mounting surface 31 is constant at 0.4 mm. By forming the electrostatic attraction electrode 40 in such a curved shape, the electrostatic attraction force acting on the substrate 2 placed on the substrate placement surface 31 can be made uniform, and the lower surface 2a of the substrate 2 and the substrate placement surface The degree of adhesion with 31 can be further increased. As a result, the cooling efficiency of the substrate 2 can be further improved, and the temperature control accuracy can be further improved.

  Since other configurations and operations of the second embodiment are the same as those of the first embodiment, the same elements are denoted by the same reference numerals and description thereof is omitted.

(Third embodiment)
In the third embodiment of the present invention shown in FIGS. 11 and 12, two electrostatic chucking electrodes 40 </ b> A and 40 </ b> B are provided on each substrate mounting portion 29 </ b> A to 29 </ b> D. These two electrostatic adsorption electrodes 40A and 40B are electrically connected to each other. In other words, in the present embodiment, the electrostatic chucking electrodes of the individual substrate platforms 29A to 29D are divided into two parts. One electrostatic attraction electrode 40 </ b> A has a flat disk shape, and has a central region 31 c in a plan view of the substrate placement surface 31 (a central region in a plan view of the substrate 2 placed on the substrate placement surface 31). Corresponding). The other electrode for electrostatic attraction 40B has a flat annular shape, and corresponds to an outer region in a plan view of the substrate placement surface 31 (an outer region in a plan view of the substrate 2 placed on the substrate placement surface 31). ). The electrostatic attraction electrode 40B is disposed below the electrostatic attraction electrode 40A. These two electrodes for electrostatic attraction 40A and 40B are arranged so that the distance from the substrate mounting surface 31 that is curved as described above is constant. For example, the two electrostatic chucking electrodes 40 </ b> A and 40 </ b> B are disposed at a depth of 0.4 mm from the bottom wall 31 a of the substrate mounting surface 31. Therefore, the electrostatic adsorption force acting on the substrate 2 placed on the substrate placement surface 31 can be made uniform, the degree of adhesion between the lower surface 2a of the substrate 2 and the substrate placement surface 31 is further increased, and the substrate 2 is cooled. Efficiency and temperature control can be further improved.

  Since other configurations and operations of the third embodiment are the same as those of the first embodiment, the same elements are denoted by the same reference numerals and description thereof is omitted.

  The present invention is not limited to the above embodiment, and various modifications as listed below, for example, are possible.

  13A and 13B show alternatives of the dielectric plate 23. FIG. In this alternative, the substrate mounting surface 31 is provided with four linear grooves 34 extending radially from the supply holes 44 and an annular groove 35 disposed inside the annular protrusion 32. The linear groove 34 and the annular groove 35 communicate with each other. By providing the linear groove 34 and the annular groove 35, the heat transfer gas ejected from the supply hole 44 diffuses more evenly in the space between the lower surface 2 a of the substrate 2 and the substrate mounting surface 31. As a result, the cooling efficiency of the substrate 2 and the accuracy of temperature control can be further increased.

  14 and 15 show various alternatives for the tray 15. In the example of FIG. 14, seven substrate housing holes 19A to 19G are formed in the tray body 15a. In the example of FIG. 15, nine substrate housing holes 19 </ b> A to 19 </ b> I for housing a rectangular substrate are formed in the tray body 15 a. 14 and 15, the shape and number of the substrate accommodation holes of the tray 15 can be variously set according to the shape and number of the substrates accommodated. For example, a single substrate accommodation hole may be provided in the tray main body 15 a to accommodate a single substrate in the tray 15. In addition, the shape and number of substrate placement portions provided on the dielectric plate 23 of the substrate susceptor 9 can be variously set according to the shape and number of substrate accommodation holes.

Experiments were conducted to confirm the effects of the present invention. Specifically, the experimental example corresponds to the first embodiment, and the substrate mounting surface 31 is not provided with the linear groove 34 and the annular groove 35 of FIGS. 13A and 13B. A spherical surface that is convex upward is used. On the other hand, in the comparative example, the linear groove 34 and the annular groove 35 of FIGS. 13A and 13B are provided on the substrate mounting surface 31, but the substrate mounting surface 31 is not a curved surface but a simple flat surface. The temperatures of the central region 2c and the outer peripheral region 2d were measured by varying the warpage amount Cw (see FIG. 7) of the substrate 2. The protrusion amount Cm of the substrate mounting surface 31 in the experimental example was set to 80 μm (Cm = 0 in the comparative example). The measurement conditions are as follows. The substrate 2 used was a sapphire substrate having a diameter of 3 inches formed with a GaN layer having a thickness of 5 μm. The warpage amount Cw of the substrate 2 was in the range of 0 to 200 μm. Cl ₂ was used as an etching gas. The supply amount of Cl ₂ was 50 sccm, and the pressure in the chamber 3 was maintained at 1.0 Pa. The high frequency power supplied to the ICP coil 5 was 900 W, and the bias power supplied to the substrate susceptor 9 was 600 W. The DC voltage applied to the electrostatic adsorption electrode 40 was + 2000V. Helium was filled at 1600 Pa as a heat transfer gas between the substrate placement surface 31 and the lower surface 2 a of the substrate 2. The temperature of the substrate susceptor 9 as the lower electrode was 15 ° C. The experimental results are shown in FIG.

  It can be confirmed from FIG. 16 that in the experimental example, the temperature of the substrate 2 is lower in both the central region 2c and the outer peripheral region 2b than in the comparative example. In the experimental example, it can be confirmed that the temperature difference between the central region 2c and the outer peripheral region 2d of the substrate 2 is smaller than that in the comparative example. In particular, when the warpage amount Cw of the substrate 2 is 100 μm, the temperature difference Δt ′ between the central region 2c and the outer peripheral edge region 2d is about 10 to 15 ° C. in the comparative example, while the central region 2c and the outer region are in the experimental example. The temperature difference Δt in the peripheral region 2d is only about 3 ° C. Accordingly, in the experimental example (the present invention), the substrate mounting surface 31 is formed in a curved shape, whereby the substrate 2 having warpage can be effectively and uniformly cooled.

  Although the present invention has been described by taking an ICP type dry etching processing apparatus as an example, the present invention is also applied to other plasma processing apparatuses such as a parallel plate type RIE (reactive ion) type dry etching and a plasma processing apparatus for plasma CVD. Applicable.

1 is a schematic cross-sectional view of a dry etching apparatus according to a first embodiment of the present invention. 1 is a schematic plan view of a dry etching apparatus according to a first embodiment of the present invention. The perspective view which shows a tray and a dielectric material board. The top view of a tray. FIG. 4B is a cross-sectional view of FIG. 4A. The top view of a dielectric material board. FIG. 5B is a cross-sectional view of FIG. 5A. FIG. 2 is a partially enlarged view of FIG. 1 (the tray is located above the dielectric plate). FIG. 2 is a partially enlarged view of FIG. 1 (the tray is lowered toward the dielectric plate). FIG. 2 is a partially enlarged view of FIG. 1 (the tray is placed on the tray support surface of the dielectric plate). The schematic diagram which shows a board | substrate. The elements on larger scale of a substrate mounting surface. The typical sectional view of the dry etching device concerning a 2nd embodiment of the present invention. The elements on larger scale of FIG. The typical sectional view of the dry etching device concerning a 3rd embodiment of the present invention. The elements on larger scale of FIG. The top view which shows the alternative of a dielectric material board. FIG. 13B is a cross-sectional view of FIG. The top view which shows the 1st alternative of a tray. The top view which shows the 2nd alternative of a tray. The graph which shows the relationship between the curvature of a board | substrate, and temperature.

DESCRIPTION OF SYMBOLS 1 Dry etching apparatus 2 Substrate 2a Lower surface 2b Center 2c Center region 2d Outer peripheral edge region 3 Chamber 3a Gate 3b Etching gas supply port 3c Exhaust port 4 Top plate 5 ICP coil 6 Matching circuit 7 High frequency power source 9 Substrate susceptor 10 Load dock chamber 12 Etching Gas supply source 13 Vacuum exhaust device 15 Tray 15a Tray main body 15b Upper surface 15c Lower surface 15d Hole wall 15e Positioning notch 16 Transfer arm 16a Positioning protrusion 17 Drive device 18 Lifting pins 19A to 19D Substrate receiving hole 21 Substrate support portion 21a Upper surface 21b Front end surface 22A , 22B sensor 23 dielectric plate 24 metal plate 25 spacer plate 26 guide cylinder 27 ground shield 28 tray support surface 29A to 29D substrate mounting portion 31 substrate mounting surface 31a bottom wall 31b center 31c central region 31d Outer peripheral edge region 32 Circular protrusion 33 Cylindrical protrusion 34 Linear groove 35 Circular groove 36 Circular opening 40, 40A, 40B Electrostatic adsorption electrode 41 DC power supply 42 Resistance 43 DC voltage application mechanism 44 Supply hole 45 Heat transfer Gas supply mechanism 46 Heat transfer gas source 47 Supply flow path 48 Flow meter 49 Flow control valve 50 Pressure gauge 51 Discharge flow path 52 Cut-off valve 53 Bypass flow path 54 Exhaust port 56 High frequency application mechanism 57 High frequency power supply 58 Variable capacity capacitor 59 Cooling Mechanism 60 Refrigerant flow path 61 Refrigerant circulation device 63 Controller

Claims (5)

A depressurizable chamber;
A plasma generation source for generating plasma in the chamber;
A substrate receiving hole provided in the chamber, the substrate receiving hole penetrating in the thickness direction, and protruding from a hole wall of the substrate receiving hole and supporting an outer peripheral edge portion of a lower surface of the substrate accommodated in the substrate accommodating hole. A tray that can be carried in and out,
A tray support portion provided in the chamber and supporting a lower surface of the tray that accommodates the substrate carried into the chamber, and protrudes upward from the tray support portion, and the substrate receiving hole from the lower surface side of the tray And a substrate mounting portion on which a lower surface of the substrate is mounted on a substrate mounting surface which is an upper end surface thereof, and the substrate mounting surface is an upwardly convex curved surface When,
An electrostatic chucking electrode for electrostatically chucking the substrate on the substrate mounting surface, at least part of which is built in the substrate mounting unit;
A DC voltage application mechanism for applying a DC voltage to the electrostatic adsorption electrode;
A heat transfer gas supply mechanism for supplying a heat transfer gas to a space between the substrate and the substrate mounting surface ;
The substrate is a substrate obtained by epitaxially growing a GaN layer on a sapphire substrate, and has a warp generated during epitaxial growth,
The plasma processing apparatus, wherein a curvature of the substrate mounting surface is smaller than a curvature of warpage of the substrate . The plasma processing apparatus according to claim 1, wherein the electrostatic chucking electrode has a curved surface shape along the substrate mounting surface. The plasma processing apparatus according to claim 1, wherein the electrostatic adsorption electrode includes a plurality of portions arranged along the substrate mounting surface. The distance from the lower surface of the tray to the upper surface of the substrate support portion is such that the lower surface of the substrate placed on the substrate placement surface is separated from the substrate support portion of the tray by a predetermined amount. The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus is set to be shorter than a distance from the substrate mounting surface to the substrate mounting surface. A plurality of the substrate accommodation holes are provided in the tray,
5. The dielectric member according to claim 1, wherein the dielectric member includes a plurality of the substrate mounting portions, and each of the substrate mounting portions is inserted into each of the substrate receiving holes. The plasma processing apparatus according to item.

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