Holding device

Abstract

To provide a holding device capable of improving a processing speed in an outer peripheral area of a target to be held.SOLUTION: In an electrostatic chuck 1 comprising a tabular member 10, a base member 20 and a junction layer 30 joining the tabular member 10 and the base member 20, the tabular member 10 includes an inside part 10a in a central part in a surface direction and an outside part 10b in an outer peripheral part in the surface direction. The junction layer 30 includes a first junction layer 30a, which is disposed between the inside part 10a of the tabular member 10 and the base member 20, and a second junction layer 30b which is disposed between the outside part 10b of the tabular member 10 and the base member 20. A total value of thermal resistance in the outside part 10b of the tabular member 10 and thermal resistance in the second junction layer 30b is smaller than a total value of thermal resistance in the inside part 10a of the tabular member 10 and thermal resistance in the first junction layer 30a.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a holding device for holding an object. [Background technology]

[0002] In the semiconductor manufacturing process, an electrostatic chuck (holding device) is used to hold a semiconductor wafer. Such an electrostatic chuck holds a semiconductor wafer (object) on the mounting surface. The ceramic member (plate-shaped member) has a chuck electrode inside. Then, a voltage is applied to the chuck electrode to generate an electrostatic attraction force. The semiconductor wafer is sucked and held by the pressure sensor (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6806051 [Patent Document 2] Patent No. 6894000 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned electrostatic chuck is not suitable for various processes on the semiconductor wafer it holds. The diameter of the plate-like member is slightly smaller than the diameter of the semiconductor wafer so that the plate-like member does not wear out during processing. The chuck electrode inside the plate-shaped member is insulated. To ensure the reliability, the plate-shaped member is only positioned slightly inside the outermost periphery. It is not placed.

[0005] Therefore, the chucking force of the semiconductor wafer held by the electrostatic chuck is such that the outer periphery is inward (center As a result, the semiconductor with low adhesion is The heat dissipation at the outer periphery of the wafer becomes poor, causing it to become too hot, and this can lead to problems in the processing of the semiconductor wafer. There is a risk that the processing speed (for example, etching rate) will decrease.

[0006] In recent years, a high bias voltage has been applied to the electrostatic chuck (used at high power). As the amount of heat input to semiconductor wafers increases, the chucking force of the target object is also increasing. The temperature often rises suddenly in the peripheral area where the temperature is likely to be low. In this region, the decrease in processing speed becomes noticeable.

[0007] Therefore, the present disclosure has been made to solve the above-mentioned problems, and the object of the present disclosure is to The object of the present invention is to provide a holding device that can improve the processing speed in the outer peripheral area of ​​an object. do. [Means for solving the problem]

[0008] In order to solve the above problems, one aspect of the present disclosure is to a plate-like member, a base member, and a bonding layer that bonds the plate-like member and the base member; In the holding device provided with the plate-like member has an inner portion at a center portion in a surface direction and an outer portion at an outer periphery in a surface direction, The bonding layer is a first bonding layer disposed between the inner portion of the plate-like member and the base member. and a second bonding layer disposed between the outer portion of the plate-shaped member and the base portion, The sum of the thermal resistance of the outer portion of the plate-shaped member and the thermal resistance of the second bonding layer is The thermal resistance of the inner portion of the heat exchanger is smaller than the sum of the thermal resistance of the inner portion of the heat exchanger and the thermal resistance of the first bonding layer.

[0009] In this holding device, the sum of the thermal resistance of the outer portion of the plate-shaped member and the thermal resistance of the second bonding layer is The thermal resistance of the inner part of the plate-shaped member is smaller than the sum of the thermal resistance of the first bonding layer and the thermal resistance of the inner part of the plate-shaped member. This makes it easier to reduce the temperature of the side of the plate-like member on which the focus ring is placed. The temperature of the outer portion is controlled to be lower than the temperature of the inner portion of the plate-like member on which the object is placed. It is possible.

[0010] Here, the plasma dry etching process includes an etching process and a deposition process. The process can be controlled by changing the gas species. .

[0011] The gases used in the etching process are, for example, CF4, C2F6, C4F8, etc. It may contain a mixture of Ar, He, N2, etc., which function as a carrier gas. The etching process gas in the plasma becomes radicals and is heated to a high temperature. Indeed, as the reaction progresses and radicals are consumed, they tend to be transported to the higher temperature side. To control the temperature of the target object during the etching process to be higher than the temperature of the focus ring As a result, the radicals are easily transported to the object side, and as a result, the outermost region of the object ( The etching rate of the edge is improved.

[0012] In contrast, the gases used in the deposition process are, for example, CHF3, CH2F 2, may contain gases such as CH3F, Ar, He, N2 acting as carrier gases The deposition process may be a mixed gas of an etching level. This is a process in which reaction products are generated to control the rate of deposition. It becomes difficult to etch during the etching process. Deposition process in plasma The gas becomes a radical, and the lower the temperature, the more reaction products are generated and deposited, and the more radicals are transported. During the deposition process, the temperature of the focus ring is easily affected by the temperature of the target. By controlling the temperature lower than the target temperature, radicals are more easily transported to the focus ring side. As a result, deposition occurs and accumulates locally at the outermost periphery (edge) of the object. As a result, the etching rate increases during the etching process.

[0013] Therefore, according to this holding device, the temperature of the outer part of the plate-like member is controlled by the temperature of the inner part of the plate-like member. By controlling the speed lower than For example, the etching rate can be improved.

[0014] In the above-mentioned holding device, an inner portion of the plate-shaped member and an outer portion of the plate-shaped member are formed of different materials; The thermal resistance of the outer portion of the plate-like member is preferably smaller than the thermal resistance of the inner portion of the plate-like member. I wish.

[0015] In this way, the inner and outer parts of the plate-like member are formed from different materials. This allows, for example, the outer portion to be made of a material with a higher thermal conductivity than the inner portion. This makes it possible to further reduce the thermal resistance of the outer portion of the plate-shaped member and the thermal resistance of the inner portion of the plate-shaped member. Therefore, the temperature of the outer portion of the plate-like member on which the focus ring is disposed can be further reduced. Therefore, the processing speed at the outermost edge of the object being held (for example, The etching rate can be further improved.

[0016] In addition, in any of the above-mentioned holding devices, The bonding surface between the inner portion of the plate-like member and the first bonding layer is perpendicular to the surface direction of the bonding surface. the outer surface of the plate-like member and the second bonding layer are disposed at different positions in the direction of the plate-like member. It is preferable that

[0017] In this way, in the direction perpendicular to the surface direction of the bonding surface, the inner part of the plate-like member and the first bonding layer and a bonding surface between the outer portion of the plate-like member and the second bonding layer are disposed at different positions. By this, the position of the mounting surface of the focus ring (the upper surface of the outer part of the plate-like member) can be adjusted arbitrarily. This allows the position of the focus ring to be freely changed.

[0018] As a result, the temperature of the outer portion of the plate-like member on which the focus ring is disposed can be controlled to a desired temperature. This allows for controlling the movement of the etching process gas in the plasma. This makes it easier to transport radicals to the outermost region of the object, making it easier to hold them. Improving the processing speed (e.g., etching rate) at the outermost periphery (edge) of the object This can be done.

[0019] In addition, in any of the above-mentioned holding devices, The outer portion of the plate-like member preferably has an electrode therein.

[0020] In this way, an electrode (an electrode connected to a DC power source or an AC power source) is provided on the outer side of the plate-shaped member. By providing at least one of them, the forging can be performed by a chuck electrode connected to a DC power supply. The adhesion force of the dust ring can be improved, which improves the heat dissipation of the focus ring. As a result, it is possible to prevent a sudden rise in temperature at the outermost edge of the object being held. In addition, plasma is generated by applying high or low frequency waves to the electrodes connected to an AC power source. Therefore, the outermost periphery of the object can be controlled and transported. This can further improve the processing speed in the edge region.

[0021] In addition, in any of the above-mentioned holding devices, The thickness of the inner portion of the plate-like member is preferably greater than the thickness of the outer portion of the plate-like member. stomach.

[0022] In this way, by making the outer portion of the plate-like member thinner than the inner portion, the plate-like member can be made to have a good resistance to the holding device. When a high frequency voltage is applied to the outer part of the plate-shaped member, the electric energy due to the dielectric loss tangent Therefore, the bias voltage in the outermost region can be applied more efficiently. This allows for an increase in the etching efficiency of ions in the plasma. Therefore, the processing speed at the outermost edge of the object to be held (for example, etching rate) This can further improve the [Effects of the Invention]

[0023] According to the present disclosure, it is possible to improve the processing speed in the outer peripheral area of ​​the held object. A retaining device may be provided. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a schematic perspective view of an electrostatic chuck according to an embodiment; [Figure 2] 1 is a schematic configuration diagram of an XZ cross section of an electrostatic chuck according to an embodiment. [Figure 3] 1A to 1C are diagrams showing specific examples of each member in an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0025] A holding device according to an embodiment of the present disclosure will be described in detail with reference to the drawings. In this embodiment, the holding device is, for example, an etching device (such as a plasma etching device). semiconductor manufacturing equipment such as deposition equipment (CVD deposition equipment, sputtering deposition equipment, etc.) An electrostatic chuck used in the device will be described as an example.

[0026] Therefore, the electrostatic chuck 1 of this embodiment will be described with reference to FIGS. The electrostatic chuck 1 of this embodiment attracts and holds a semiconductor wafer W (object) by electrostatic attraction. For example, it is a device for fixing a semiconductor wafer W in a vacuum chamber of a semiconductor manufacturing device. As shown in FIGS. 1 and 2, the electrostatic chuck 1 includes a plate-like member 10 and The plate-shaped member has a base member and a bonding layer that bonds the plate-shaped member and the base member.

[0027] In the following description, for convenience of explanation, the X, Y, and Z axes are defined as shown in FIG. The Z axis is an axis in the axial direction of the electrostatic chuck 1 (the vertical direction in FIG. 1 ), and The X-axis and Y-axis are radial axes of the electrostatic chuck 1, and the X-axis is an example of the thickness direction. The direction of the Y plane is an example of the "plane direction" in this disclosure.

[0028] As shown in FIG. 1, the plate-shaped member 10 is a disk-shaped member made of ceramics. Specifically, the plate-like member 10 has an inner portion 10a at the center in the XY plane direction (surface direction). and an outer portion 10b on the outer periphery in the XY plane direction (surface direction). The semiconductor wafer W is placed on the upper surface 11a of the inner portion 10a of the plate-like member 10. An annular member (focus ring FR) surrounding the semiconductor wafer W is disposed on the upper surface 11b of the wafer W. In this embodiment, the plate-like member 10 is formed by separating an inner portion 10a and an outer portion 10b. The plate-like member 10 has an inner portion 10a and an outer portion 10b. b may be connected (integral structure).

[0029] Various ceramics are used to form the plate-like member 10. However, from the viewpoint of strength, abrasion resistance, plasma resistance, etc., aluminum oxide (aluminum Ceramics mainly composed of aluminum nitride (Al2O3) or aluminum nitride (AlN) are used. It is preferable that the main component is the component with the highest content (for example, , components with a volume content of 90 vol% or more).

[0030] As shown in FIGS. 1 and 2, the inner portion 10a of the plate-like member 10 is disk-shaped. The upper surface 11a is a holding surface that holds the W, and the upper surface 11a is provided on the opposite side of the upper surface 11a in the Z-axis direction. The diameter of the inner portion 10a is, for example, 150 mm to 300 mm. The thickness of the inner portion 10a is, for example, about 1 mm to 10 mm. The thermal conductivity of the inner portion 10a is preferably within the range of 10 W / mK to 50 W / mK.

[0031] As shown in FIG. 2, the inner portion 10a of the plate-like member 10 has a chuck electrode therein. The chuck electrode 50 has, for example, a substantially circular shape when viewed in the Z-axis direction. It is made of a conductive material (for example, tungsten or molybdenum). When a voltage is applied to the electrode 50, an electrostatic attraction force (adsorption force) is generated. The semiconductor wafer W is attracted and fixed to the upper surface 11a by the attractive force.

[0032] As shown in FIGS. 1 and 2, the outer portion 10b of the plate-like member 10 is annular. The upper surface 11b on which the ring FR is disposed is provided on the opposite side of the upper surface 11b in the Z-axis direction. The outer portion 10b has a lower surface 12b. The outer portion 10b is lower than the inner portion 10a in the Z-axis direction. That is, the bonding surface between the inner portion 10a and the bonding layer 30 (second bonding layer 30b) The lower surface 12b is the bonding surface between the outer portion 10b and the bonding layer 30 (first bonding layer 30a). It is arranged at a position different from the surface 12a (lower in the Z-axis direction).

[0033] The outer diameter of the outer portion 10b is, for example, about 180 mm to 400 mm. The thickness of the portion 10b is, for example, about 1 mm to 10 mm. The thickness of the inner portion 10b is smaller (thinner) than the thickness of the inner portion 10a of the plate-like member 10. The thermal conductivity of 10b is preferably within the range of 10 W / mK to 50 W / mK.

[0034] As shown in FIG. 2, the outer portion 10b of the plate-like member 10 has a chuck electrode therein. The chuck electrode 51 has, for example, a substantially annular shape when viewed in the Z-axis direction. The conductive material is made of a conductive material (for example, tungsten or molybdenum). When a voltage is applied to the lock electrode 51, an electrostatic attraction force (adsorption force) is generated. The focus ring FR is attracted and fixed to the upper surface 11b by electrostatic attraction.

[0035] In this embodiment, the outer portion 10b of the plate-shaped member 10 is However, they may be separated from each other (separate structure) or connected to each other (integral structure). The material forming the outer portion 10b is the same as the material forming the inner portion 10a (e.g., both The outer portion 10b may be made of aluminum nitride or alumina, or may be different (for example, the outer portion 10b may be made of aluminum nitride). The inner part 10a is made of aluminium.

[0036] As shown in FIG. 1, the base member 20 is disposed on the lower surface side of the plate-like member 10. The base member 20 is formed, for example, in a cylindrical shape. In this embodiment, the base member 20 is formed on the inner side of the plate-like member 10. The portion to be joined with the base member 10a is convex. It is made of metal (for example, aluminum or aluminum alloy), but is not made of metal ( For example, ceramics, metal ceramic composite materials, etc. may be used.

[0037] As shown in FIGS. 1 and 2, the base member 20 has the inner portion 10a joined to the upper surface thereof. and an upper surface 21b to which the outer portion 10b is joined, and The upper surface of the base member 20 is provided on the opposite side to the lower surface 21b. The surfaces 21a and 21b are the lower surface 12a of the inner portion 10a of the plate-shaped member 10 and the outer surface 12b of the plate-shaped member 10. The lower surface 12b of the side portion 10b is thermally connected to the lower surface 12b via the bonding layer 30 (30a, 30b). There are.

[0038] The diameter of the base member 20 is, for example, about 180 mm to 400 mm. The thickness of the member 20 (the dimension in the Z-axis direction) is, for example, about 20 mm to 50 mm. The thermal conductivity of the material 20 (presumably aluminum) is 160W / mK to 250W / mK (preferably Preferably, it is in the range of about 230 W / mK.

[0039] The base member 20 is provided with a cooling medium (e.g., a fluorine-based inert liquid, water, etc.) for flowing therethrough. A refrigerant flow path 23 is formed for the purpose. By flowing a refrigerant through this refrigerant flow path 23, The plate-like member 10 is cooled via the bonding layer 30. This allows the semiconductor wafer W, whose temperature has risen during various processes, to be cooled, Heat is removed from the solid wafer W (heat sink).

[0040] As shown in FIGS. 1 and 2, the bonding layer 30 is disposed between the plate-like member 10 and the base member 20. The bonding layer 30 bonds the plate-shaped member 10 and the base member 20 together. a first bonding layer 30a disposed between the inner portion 10a of the plate-like member 10 and the base member 20; and a second bonding layer 30b disposed between the outer portion 10b of the base member 20 and the base member 20. .

[0041] As shown in FIG. 2, the first bonding layer 30a is bonded to the lower surface 12a of the inner portion 10a of the plate-shaped member 10. and the upper surface 21a of the base member 20, and The first bonding layer 30a is made of, for example, a silicone resin or an acrylic resin. It is made of resin adhesive such as resin or epoxy resin.

[0042] The thickness (dimension in the Z-axis direction) of the first bonding layer 30a is, for example, 0.05 mm to 0.5 mm. The thermal conductivity of the first bonding layer 30a is, for example, 0.1 W / mK to 2.0 W / mK ( Preferably, it is within the range of 0.5 W / mK to 1.5 W / mK.

[0043] As shown in FIG. 2, the second bonding layer 30b is bonded to the lower surface 12b of the outer portion 10b of the plate-shaped member 10. The outer surface 10b of the plate-shaped member 10 and the upper surface 21b of the base member 20 are disposed between the outer surface 10b of the plate-shaped member 10 and the base member 20. The second bonding layer 30b is made of, for example, a silicone resin. Resin adhesives such as grease, acrylic resin, epoxy resin, etc., or metals whose main component is metal material It is made of bonding material.

[0044] Examples of metal bonding materials include metal adhesives that use metal powder or metal foil for bonding. , metal fibers, porous materials, mesh structures, and other metal mesh and brazing materials, Alternatively, a metal joint consisting of a plurality of columnar metal pieces and brazing material can be used. Metals that form the adhesive, metal mesh, and metal pieces include aluminum alloys, indium, Titanium, nickel, copper, brass, alloys of these, or stainless steel can be used. Cut.

[0045] The thickness (dimension in the Z-axis direction) of the second bonding layer 30b is, for example, 0.05 mm to 0.5 mm. The thermal conductivity of the second bonding layer 30b is, for example, 100 W / mK to 200 W / mK. The range of the luminance is preferably 150 W / mK to 180 W / mK.

[0046] The sum of the thermal resistance of the outer portion 10b of the plate-shaped member 10 and the thermal resistance of the second bonding layer 30b is is smaller than the sum of the thermal resistance of the inner portion 10a of the plate-shaped member 10 and the thermal resistance of the first bonding layer 30a. The thermal resistance is defined as the thickness of the material divided by the thermal conductivity of the material. To reduce the resistance, the thickness can be reduced or the thermal conductivity can be increased.

[0047] When the electrostatic chuck 1 having such a configuration is used, the semiconductor wafer W is placed on the plate-like member 10 and the focus ring FR is held on the upper surface 11a of the plate-like member 10. While the semiconductor wafer W is held on the upper surface 11b of the wafer holder 11b, various processes are performed on the semiconductor wafer W. For example, in the etching process for semiconductor wafers W, high power is used in recent years. The amount of heat input to the semiconductor wafer W is increasing. The temperature often rises suddenly in the outer peripheral region where the chucking force of the solid wafer W tends to be low, There is a risk that the etching rate (processing speed) in the outer peripheral region of the semiconductor wafer W will decrease.

[0048] Therefore, in the electrostatic chuck 1 of this embodiment, the thermal resistance of the outer portion 10b of the plate-shaped member 10 and the The sum of the thermal resistance of the first bonding layer 30b and the thermal resistance of the inner portion 10a of the plate-shaped member 10 is calculated by multiplying the thermal resistance of the first bonding layer 30b by the thermal resistance of the inner portion 10a of the plate-shaped member 10. The thermal resistance of the outer portion 10b and the second bonding layer 30a is smaller than the total thermal resistance of the outer portion 10b and the second bonding layer 30a. 3 shows examples (Examples 1 to 5) of the combination of the inner portion 10a and the first bonding layer 30b and the inner portion 10a and the first bonding layer 30a. show.

[0049] In Examples 1 to 5 shown in FIG. 3, the inner portion 1 of the plate-like member 10 is located on the side where the semiconductor wafer W is placed. The first bonding layer 30a and the first bonding layer 30b are made the same, and the plate-like member The material of the outer portion 10b of the heat sink 10 or the second bonding layer 30b is changed. Regarding each component in the specific combination example, the component on the side where the focus ring FR is mounted is , and the member on the semiconductor wafer W mounting side will be described separately.

[0050] First, the components on the side where the focus ring FR is mounted will be described. In all cases, the inner portion 10a of the plate-shaped member 10 is made of alumina, and its thermal conductivity is The coefficient is 32W / mK, the thickness is 1.5mm, and the thermal resistance is 4.7×10 -5 m 2 It is K / W. In addition, the first bonding layer 30a is made of silicone resin, and its thermal conductivity is 1 W / mK, thickness 0.1 mm, thermal resistance 1.0 × 10 -4 m 2 K / W. And the inner part The total thermal resistance of the first bonding layer 10a and the first bonding layer 30a is 1.5×10 -4 m 2 It is K / W do.

[0051] Next, a description will be given of the members on the side where the semiconductor wafer W is placed. In Example 1, a plate-shaped member The outer portion 10b of the heat sink 10 is made of alumina, and has a thermal conductivity of 32 W / mK and a thickness of is 1mm, and the thermal resistance is 3.1×10 -5 m 2 In addition, the second bonding layer 30b is It is made of silicon resin, with a thermal conductivity of 1W / mK, a thickness of 0.1mm, and a thermal Resistance is 1.0×10 -4 m 2 The outer portion 10b and the second bonding layer 30b are K / W. The total thermal resistance is 1.3 × 10 -4 m 2 It is K / W.

[0052] In Example 2, the outer portion 10b of the plate-shaped member 10 is made of alumina, and its heat conductivity is Conductivity 32W / mK, thickness 1mm, thermal resistance 3.1×10 -5 m 2 K / W. The second bonding layer 30b is made of silicone resin and has a thermal conductivity of 1.4W. / mK, thickness 0.1mm, thermal resistance 7.1×10 -5 m 2 K / W. And outside The total thermal resistance of the portion 10b and the second bonding layer 30b is 1.0×10 -4 m 2 Becoming K / W That is, in the second embodiment, the total value of the thermal resistance is smaller than that in the first embodiment.

[0053] In Example 3, the outer portion 10b of the plate-shaped member 10 is made of alumina, and its heat conductivity is Conductivity 32W / mK, thickness 1mm, thermal resistance 3.1×10 -5 m 2 K / W. The second bonding layer 30b is made of silicone resin and has a thermal conductivity of 1.4W. / mK, thickness 0.07mm, thermal resistance 5.0×10 -5 m 2 K / W. And outside The total thermal resistance of the side portion 10b and the second bonding layer 30b is 8.1×10 -5 m 2 K / W In other words, in the third embodiment, the total value of the thermal resistance is even smaller than in the second embodiment. do.

[0054] In Example 4, the outer portion 10b of the plate-shaped member 10 is formed of aluminum nitride, Its thermal conductivity is 170 W / mK, its thickness is 1 mm, and its thermal resistance is 5.9 × 10 -6 m 2 At K / W The second bonding layer 30b is made of a silicone resin, and its thermal conductivity is is 1.4W / mK, thickness is 0.07mm, and thermal resistance is 5.0×10 -5 m 2 It is K / W. The total thermal resistance of the outer portion 10b and the second bonding layer 30b is 5.6×10 -5 m 2 K / W. In other words, in the fourth embodiment, the total value of the thermal resistance is even smaller than in the third embodiment. It has become.

[0055] In Example 5, the outer portion 10b of the plate-shaped member 10 is made of alumina, and its heat conductivity is Conductivity 32W / mK, thickness 1mm, thermal resistance 3.1×10 -5 m 2 K / W. The second bonding layer 30b is made of an aluminum alloy, and the thermal conductivity of the aluminum alloy is 170 W / mK, thickness 0.3 mm, thermal resistance 1.8×10 -6 m 2 K / W. And outside The total thermal resistance of the side portion 10b and the second bonding layer 30b is 3.3×10 -5 m 2 K / W In other words, in the fifth embodiment, the total value of the thermal resistance is even smaller than in the fourth embodiment. do.

[0056] As illustrated in Examples 1 to 5, the thermal resistance of the outer portion 10b of the plate-like member 10 and the second bonding layer 3 The sum of the thermal resistance of the inner portion 10 of the plate-shaped member 10 and the thermal resistance of the inner portion 10 of the plate-shaped member 10 (on the side where the focus ring FR is placed) is a and the thermal resistance of the first bonding layer 30a (on the semiconductor wafer W mounting side). Therefore, the temperature of the outer portion 10b of the plate-shaped member 10 can be easily reduced. The temperature at the outer portion 10b of the plate-shaped member 10 on which the focus ring FR is disposed is The temperature is controlled to be lower than the temperature of the inner portion 10a of the plate-like member 10 on which the semiconductor wafer W is placed. This can be done.

[0057] During the etching process for the semiconductor wafer W, By controlling the temperature of the semiconductor wafer W to be higher than the temperature of the focus ring FR, Therefore, the etching rate of the outermost peripheral region (edge) of the semiconductor wafer W can be improved. The etching process gas in the plasma becomes radicals, and the higher the temperature, the more the reaction progresses. This is because radicals are consumed and are easily transported to the high temperature side. In the process, the temperature of the focus ring FR is controlled to be lower than the temperature of the semiconductor wafer W. As a result, deposition occurs locally at the outermost periphery (edge) of the semiconductor wafer W. The lower the temperature, the more reaction products are generated and deposited, and the radicals are deposited at the lower temperature. As a result, the etching rate is increased during the etching process. It can be raised.

[0058] Therefore, according to the first to fifth embodiments, the outside of the plate-like member 10 on which the focus ring FR is disposed is The temperature of the side portion 10b is set to be lower than the temperature of the inner portion 10a of the plate-like member 10 on which the semiconductor wafer W is placed. Since the temperature can be controlled to be lower than that of the semiconductor wafer W, the edge of the semiconductor wafer W can be The chin rate can be improved.

[0059] In the electrostatic chuck 1 of the present embodiment (Examples 1 to 5), the inner portion 10 of the plate-like member 10 a and the first bonding layer 30a (the lower surface 12a of the inner portion 10a) in the Z-axis direction. The bonding surface between the outer portion 10b of the plate-shaped member 10 and the second bonding layer 30b (the lower surface 12b of the outer portion 10b) ) are located in a different position.

[0060] As a result, the arrangement position (height position) of the outer portion 10b of the plate-like member 10 in the Z-axis direction is Since it can be freely set, the mounting surface of the focus ring FR (the outer surface of the plate-like member 10) The position of the upper surface 11b of the portion 10b can be adjusted arbitrarily. The position of the focus ring FR can be freely changed. The temperature of the outer portion 10b of the plate-like member 10 can be controlled to a desired temperature. This makes it possible to control the movement of radicals in the plasma, and therefore, the radicals can be transported to the semiconductor wafer. By making it easier for the wafer W to be transported to the outermost periphery (edge) of the semiconductor wafer W, The etching rate can be improved.

[0061] In the electrostatic chuck 1 of the present embodiment (Examples 1 to 5), the outer portion 10 of the plate-like member 10 The chuck electrode 51 is disposed at b. Therefore, the chucking force of the focus ring FR is increased. This improves the heat dissipation of the focus ring FR, This can prevent a sudden rise in temperature at the outermost peripheral region (edge) of the semiconductor wafer W. This makes it possible to prevent a decrease in the etching rate at the outermost peripheral region (edge) of the semiconductor wafer W. can.

[0062] Furthermore, in the electrostatic chuck 1 of this embodiment (Examples 1 to 5), the outer surface of the plate-shaped member 10 The side portion 10b is thinner than the inner portion 10a. When a voltage is applied, the electric energy due to the dielectric loss tangent is This reduces the loss of radicals in the plasma. Since it is possible to easily move to the outermost peripheral area, The etching rate can be further improved.

[0063] As in the fourth embodiment, the inner portion 10a and the outer portion 10b of the plate-like member 10 are The outer portion 10b is made of a material having a higher thermal conductivity than the inner portion 10a. By forming the plate-shaped member 10, the thermal resistance of the outer portion 10b of the plate-shaped member 10 is The thermal resistance of a can be made even smaller than in Examples 1 to 3. According to this, the temperature of the outer portion 10b of the plate-shaped member 10 on which the focus ring FR is disposed is further increased. Therefore, the etching rate at the outermost periphery (edge) of the semiconductor wafer W can be reduced. This can further improve the performance.

[0064] Here, as in Examples 1 to 3, the plate-like member 10 has an inner portion 10a and an outer portion 10b. Even if they are made of the same alumina, the inner portion 10a is made of low-purity alumina, and the outer portion By using high-purity alumina for the outer portion 10b, the thermal conductivity of the outer portion 10b is increased to that of the inner portion 10a. Low-purity alumina can be sintered using sintering aids such as glass. Alternatively, the outer portion 10b can be densified (for example, By sintering the outer portion at a higher temperature, the thermal conductivity of the outer portion 10b can be increased to that of the inner portion 10b. By taking such measures, the thermal conductivity of the focus ring can be increased. Since the temperature of the outer portion 10b of the plate-shaped member 10 on which the guide FR is arranged can be lowered, The etching rate at the outermost peripheral region (edge) of the solid wafer W can be improved.

[0065] The interfacial thermal resistance (between the plate-like member 10 and the bonding layer 30 / between the bonding layer 30 and the base member 20) ) also, the side where the focus ring FR is mounted (the outer portion 10b side) is closer to the side where the semiconductor wafer W is mounted (the inner This also reduces the thermal resistance of the outer portion 10b of the plate-shaped member 10. and the thermal resistance of the second bonding layer 30b is calculated by multiplying the thermal resistance of the inner portion 10a of the plate-shaped member 10 by the thermal resistance of the first bonding layer 30b. This contributes to making the thermal resistance smaller than the total value of the thermal resistance of the bonding layer 30a.

[0066] In addition, as in Example 5, the second bonding layer 30b is made of a metal bonding material (aluminum alloy). By forming the above, the thermal resistance of the outer portion 10b of the plate-shaped member 10 and the first The total value of the thermal resistance of the second bonding layer 30b and the thermal resistance of the second bonding layer 30b (on the side where the focus ring FR is placed) is calculated by The sum of the thermal resistance of the inner portion 10a and the thermal resistance of the first bonding layer 30a (semiconductor wafer W mounting side) Therefore, the plate-like structure on which the focus ring FR is placed can be made even smaller. Since the temperature of the outer portion 10b of the member 10 can be further reduced, the temperature of the semiconductor wafer W can be further reduced. The etching rate in the outer periphery (edge) can be further improved.

[0067] As described above, according to the electrostatic chuck 1 of this embodiment, the outer portion 10b of the plate-shaped member 10 The sum of the thermal resistance of the inner portion 10a of the plate-shaped member 10 and the thermal resistance of the second bonding layer 30b is and the thermal resistance of the first bonding layer 30a. Therefore, the plate-like member on which the focus ring FR is disposed can be lowered in temperature. The temperature at the outer portion 10b of the plate-like member 10 on which the semiconductor wafer W is placed is measured. Therefore, the temperature of the outermost semiconductor wafer W can be controlled to be lower than that of the outermost semiconductor wafer W. The etching rate at the edge can be improved.

[0068] It should be noted that the above-described embodiments are merely examples and do not limit the present disclosure in any way. Of course, various improvements and modifications are possible within the scope of the present invention. For example, in the above embodiment, the electrode provided inside the outer portion 10b of the plate-shaped member 10 is a chuck electrode. Although the case of the electrode 51 is illustrated, the internal electrode is not limited to the chuck electrode. For example, By providing a high frequency electrode, radicals in the plasma can be Since the wafer W can be transported to the outermost periphery (edge) of the semiconductor wafer W, The etching rate in the step (2) can be further improved. [Explanation of symbols]

[0069] 1. Electrostatic chuck 10 Plate-shaped member 10a Medial part 10b Outer part 20 Base member 30 Bonding layer 30a 1st bonding layer 30b 2nd bonding layer 50 Chuck electrode 51 Chuck electrode FR focus ring W Semiconductor wafer

Claims

1. A holding device including a plate-like member, a base member, and a joint portion that joins the plate-like member and the base member, the plate-like member has an inner portion at a center portion in a surface direction and an outer portion at an outer periphery in a surface direction, the joint portion includes a first joint portion located between an inner portion of the plate-like member and the base member, and a second joint portion located between an outer portion of the plate-like member and the base member, The sum of the thermal resistance of the outer portion of the plate-shaped member and the thermal resistance of the second joint portion is smaller than the sum of the thermal resistance of the inner portion of the plate-shaped member and the thermal resistance of the first joint portion, and the purity of the material in the outer portion of the plate-shaped member is higher than the purity of the material in the inner portion of the plate-shaped member. A holding device characterized by:

2. 2. The holding device according to claim 1, The inner portion of the plate-shaped member and the outer portion of the plate-shaped member are both formed of the same ceramic material. A holding device characterized by:

3. 3. The holding device according to claim 2, The ceramic material is aluminum oxide or aluminum nitride. A holding device characterized by:

4. 2. The holding device according to claim 1, The first joint portion and the second joint portion are both formed of materials having the same thermal resistance. A holding device characterized by:

5. 5. The holding device according to claim 4, The second bonding portion is a metal bonding material. A holding device characterized by:

6. In the holding device described in claim 1, Both the outer and inner parts of the plate-like member are provided with electrodes therein. A holding device characterized by:

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