JP5264559B2 - Susceptor and plasma processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a susceptor low in thermal expansion, high in mechanical strength and excellent in corrosion resistance. <P>SOLUTION: The susceptor 105 is provided in a plasma processing device 10. The susceptor 105 has a base material 110 on which a substrate G is mounted. The base material 110 is formed using a plurality of clad materials constituted of a titanium base metal 110a and a nickel or aluminum plied timber 110b. The plurality of clad materials are joined with one another such that the base metal 110a is covered with the plied material 110b. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a susceptor for placing an object to be processed and a plasma processing apparatus provided with the susceptor.

Conventionally, there has been proposed a plasma processing apparatus that performs plasma processing such as film formation and etching on a substrate by plasma generated by exciting a gas (see, for example, Patent Document 1). For example, in the plasma processing apparatus 90 shown in FIG. 8, a susceptor 900 is disposed in the center of the interior. The susceptor 900 has a base material 905 on which the substrate G is placed. The base material 905 is formed of carbon or aluminum, is sprayed 910 with alumina (Al ₂ O ₃ ), yttria (Y ₂ O ₃ ), or the like, and is covered with an alumina insulator 912. A support 990 that supports the susceptor 900 is connected to the processing vessel Ch via a bellows 995 and is grounded.

  A power supply rod 915 is connected to the base material 905 and a heater 920 is embedded. In addition, a high frequency power source 930 is connected to the power feeding rod 915 via a matching unit 925. The high frequency power output from the high frequency power source 930 is applied to the susceptor 900 functioning as a lower electrode from the power supply point 915a through the power supply rod 915. A heater source 935 is connected to the heater 920. The AC power output from the heater source 935 is applied to the heater 920, and the temperature of the susceptor 900 is adjusted accordingly. A temperature sensor 940 is attached inside the base material, and the inside of the susceptor 900 is maintained at a high temperature of about 200 to 450 ° C. by the control of the temperature controller 945 according to the sensor value. Further, the substrate G is electrostatically attracted to the susceptor 900 by supplying a DC voltage from the high-voltage DC power supply 955 to the electrostatic chuck 950. The gas supplied from the gas supply source 960 is supplied into the processing chamber through the gas shower head 965. The supplied gas is turned into plasma by the energy of the high frequency power, and the substrate G is subjected to a desired process by the plasma. A plurality of through holes 970 pass through the susceptor 900. An elevating mechanism 980 to which lift pins 975 are attached is provided below the through hole 970, and the substrate G is transported by elevating the lift pins 975.

JP 2008-42116 A

For example, FIG. 9 shows an enlarged view of the susceptor portion of the conventional plasma processing apparatus shown in FIG. During the process, in order to set the temperature of the substrate G on the susceptor to about 350 ° C., the susceptor 900 needs to be heated to about 450 ° C. by the heater 920. However, since aluminum and nickel used for the base material 905 have a large coefficient of linear expansion during heating, the expansion and contraction is large. For example, at 20 ° C. to 350 ° C., the average linear thermal expansion coefficient of aluminum is about 25 × 10 ⁻⁶ / K, and the average linear thermal expansion coefficient of nickel is about 15 × 10 ⁻⁶ / K. On the other hand, the average linear thermal expansion coefficient of alumina is 7.8 × 10 ⁻⁶ / K. Thus, the linear thermal expansion coefficient of aluminum or nickel is two to three times larger than the linear thermal expansion coefficient of alumina. Since the length from the center to the end of the base material 905 is 1600 mm, when the temperature of the base material 905 made of aluminum is raised from 25 ° C. of the room temperature to 450 ° C. of the process temperature in this state, the center of the base material 905 The length to the end extends about 17 mm. On the other hand, the elongation of alumina is only about 5 mm.

  Thus, when the difference in thermal expansion between the aluminum of the substrate 905 and the surrounding alumina is large, particularly large stress is generated at the joint surface between the substrate 905 and the alumina spraying 910 due to repeated heating and cooling, and the alumina spraying. In some cases, 910 was cracked or peeled off. Further, the substrate 905 and the alumina insulator 912 are in contact with each other, and any material may be damaged or cracked. Also, the positions and dimensions of the plurality of through-holes 970 are changed, which hinders the lifting and lowering operation of the lift pins 975, or the lift pins 975 that penetrate the through-holes 970 are displaced to the outside of the substrate G so that the substrate G cannot be raised. In some cases, inconvenience may occur in the conveyance of the substrate G.

  When the high-frequency current output from the high-frequency power source 930 flows on the metal surface of the susceptor 900, the gap α between the support 990 and the alumina insulator 912 shown in FIG. It is necessary to prevent the occurrence of abnormal discharge. However, in the conventional apparatus, since the thermal expansion difference between the aluminum of the base material 905 and the surrounding alumina is large, the gap α between the alumina insulator 912 and the support 990 becomes 0.5 mm or more, and this gap α In some cases, plasma entered into the tube and abnormal discharge occurred.

  Furthermore, with the recent increase in the size of the substrate G, there is an increasing demand for increasing the size of the susceptor 900. At present, the susceptor 900 must be enlarged in accordance with the substrate sizes of G8 and G10. Therefore, in the case of a 3000 mm × 3000 mm substrate, the size of the susceptor 900 needs to be about 3100 mm × 3100 mm. If this is attempted to be realized with carbon, for example, the mechanical strength of the carbon is weak, so the plate warps. On the other hand, it is conceivable to bond a plurality of carbons to handle a large size susceptor. However, dust is generated from the bonded part, and the mechanical strength cannot be maintained on the bonded surface. There is a limit to enlargement.

  Therefore, the present invention provides a susceptor having low thermal expansion, high mechanical strength, and excellent corrosion resistance, and a plasma processing apparatus provided with the susceptor.

  In order to solve the above problems, according to an aspect of the present invention, there is provided a susceptor provided in a plasma processing apparatus, wherein the susceptor includes a base material on which an object to be processed is placed, and the base The material is formed by using a plurality of clad materials formed from a titanium base material and a nickel or aluminum composite material, and joining the plurality of clad materials so that the base material is covered with the composite material. A susceptor is provided.

  According to this, a plurality of clad materials are used for the base material of the susceptor. The clad material uses titanium as a base material and nickel or aluminum as a composite material. Each clad material is manufactured by explosive bonding (explosion bonding) as shown in FIGS. Specifically, aluminum or nickel plates are stacked on titanium with a gap, and an explosive is set thereon. Due to the high energy during the explosion of the explosive, the composite material is driven at high speed on the base material surface, and liquefied metal (metal jet) is generated from the collision surface between the composite material and the base material. The metal jet removes deposits and adsorbed gas on the surface of the base material and activates the surface of the base material and the composite material. When this is crimped, it is attracted and joined by the atomic force of both the base metal and the composite metal. Since explosive pressure bonding is performed instantaneously, it is cold pressure bonding, and the joining surface is rippled Pa in FIG. 3C, and Kalman vortex Pb is generated in some places.

The average linear thermal expansion coefficient of titanium is 9.6 × ^{10 -6} /K~10.0×10 -6 / K when 200 ° C. to 500 ° C., an average line of the average linear thermal expansion coefficient and nickel aluminum It is smaller than the thermal expansion coefficient and close to the average linear thermal expansion coefficient of alumina. Therefore, when titanium is used as a base material, aluminum or nickel is used as a composite material, and alumina is sprayed onto the aluminum or nickel composite material, the difference in thermal expansion between the sprayed alumina and the susceptor can be reduced. As a result, it is possible to create a structure in which stress is not easily concentrated even when the susceptor is heated from a room temperature of 20 ° C. to a process temperature of 450 ° C. or cooled. Thereby, it can suppress that the sprayed alumina cracks or peels off and causes a contamination. Furthermore, as described above, by using a clad material in which the base material and the composite material are firmly joined at the joining surface, peeling and cracking can be further prevented and the mechanical strength of the susceptor can be increased.

  Here, instead of using a clad material of titanium and nickel or titanium and aluminum, when aluminum is sprayed onto titanium, aluminum becomes porous, so that the titanium is corroded through the gas used for plasma treatment. There is a fear. Moreover, when aluminum is welded to titanium, the problem that aluminum peels from titanium due to corrosion of titanium remains. However, according to the susceptor according to the present invention, the surface of the base material made of titanium is covered with a composite material made of nickel or aluminum and is not exposed to the outside. Further, in the clad material, aluminum or nickel covering titanium does not pass gas. For this reason, the susceptor excellent in corrosion resistance which prevented corrosion of titanium can be provided. Furthermore, since the base material has low thermal expansion, it is possible to manage gaps generated between different members, and to prevent abnormal discharge.

  The thickness of the composite is preferably 1/10 to 3/2 times the thickness of the base material. This takes into account corrosion resistance, welding strength, temperature distribution, and the like.

  Either alumina or yttria may be sprayed on the composite material exposed on the surface of the substrate. Further, it is more preferable to perform sandblasting or alumite treatment as the surface treatment because the emissivity is increased. In terms of material, alumina has a high emissivity and can efficiently release heat. Therefore, it is particularly effective to thermally spray ceramics such as alumina.

  The base material may be provided with a through-hole through which the lift pin passes, and a pipe-like tube made of nickel may be fitted into the through-hole.

  The base is provided with a through-hole through which the lift pin passes, and two ring-shaped members made of nickel are joined to the openings at both ends of the through-hole, respectively, and a bellows made of nickel Both end portions of the ring may be joined to the two ring-shaped members.

  The plurality of clad materials may be screwed, and the screw holes may be filled with nickel.

  The plurality of clad materials have through holes for joining at positions where the clad materials are joined to each other, and the communicated through holes are the same as the base material and the composite material of the joined clad materials. You may block | close with the obstruction | occlusion member which consists of thickness and the same substance.

  In order to solve the above-described problems, according to another aspect of the present invention, a processing chamber that plasmas a target object by exciting a gas by energy of a plasma source, and a susceptor provided inside the processing chamber; The susceptor has a base material on which an object to be processed is placed, and the base material is a clad formed of a titanium base material and a nickel or aluminum composite material. There is provided a plasma processing apparatus using a plurality of materials and joining the plurality of clad materials so that the base material is covered with the composite material.

  According to this, a plurality of clad materials formed of a titanium base material and a nickel or aluminum composite material are used for the susceptor. For this reason, a susceptor having low thermal expansion and high mechanical strength can be constructed. Further, the plurality of clad materials are joined so that the surface of the base material is not exposed by the composite material. For this reason, the susceptor having such a configuration is also excellent in corrosion resistance. As a result, it is possible to manufacture a large susceptor that matches the size of the object to be processed. Thereby, a plasma processing apparatus capable of performing plasma processing on a large object to be processed can be provided.

  As described above, according to the present invention, it is possible to provide a susceptor having low thermal expansion and high mechanical strength and corrosion resistance, and a plasma processing apparatus provided with the susceptor.

It is a longitudinal cross-sectional view of the plasma processing apparatus which concerns on one Embodiment of this invention. It is a longitudinal cross-sectional view of the susceptor vicinity which concerns on the same embodiment. It is the figure which showed the manufacturing method of the clad material. It is the figure which showed the manufacturing method of the base material using the some clad material which concerns on the same embodiment. FIGS. 5A and 5B are longitudinal sectional views of through holes provided in the base material according to the embodiment. 6A and 6B are views showing a method for joining a plurality of clad materials according to the embodiment. It is the longitudinal cross-sectional view of another plasma processing apparatus. It is the longitudinal cross-sectional view of the conventional plasma processing apparatus. It is a longitudinal cross-sectional view of the susceptor vicinity which concerns on the conventional plasma processing apparatus.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description and the accompanying drawings, the same reference numerals are given to the constituent elements having the same configuration and function, and redundant description is omitted.

(Outline of microwave plasma processing equipment)
First, the configuration of a microwave plasma processing apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 schematically shows a longitudinal sectional view of the apparatus.

  The microwave plasma processing apparatus 10 includes a processing container 100 for plasma processing a glass substrate (hereinafter referred to as “substrate G”). The processing container 100 includes a container body 200 and a lid body 300. The container body 200 has a bottomed cubic shape with an upper portion opened, and the opening is closed by a lid 300. The lid body 300 includes an upper lid body 300a and a lower lid body 300b. An O-ring 205 is provided on a contact surface between the container main body 200 and the lower lid body 300b, whereby the container main body 200 and the lower lid body 300b are hermetically sealed to define a processing chamber. An O-ring 210 and an O-ring 215 are also provided on the contact surface between the upper lid body 300a and the lower lid body 300b, whereby the upper lid body 300a and the lower lid body 300b are sealed. The container body 200 and the lid body 300 are made of a metal such as an aluminum alloy, for example, and are electrically grounded.

  A susceptor 105 for placing the substrate G is provided in the center of the processing container. A clad material is used for the base material 110 of the susceptor 105. The clad material used for the susceptor 105 will be described later. The surface of the substrate 110 is sprayed with alumina (see alumina spraying 110c in FIG. 2) and covered with an alumina insulator 115. Yttria may be sprayed instead of alumina spraying. The susceptor 105 is supported by a support body 120 made of aluminum. A baffle plate 125 is provided around the susceptor 105 to control the gas flow in the processing chamber to a preferable state.

  A hollow conductive member 130 is provided at the lower center of the substrate 110 and protrudes outside the container. A high-frequency power source 140 is connected to the conductive member 130 via a matching unit 140 a in the matching box 185. When high frequency power from the high frequency power supply 140 is applied to the conductive member 130, a high frequency current propagates from the surface of the conductive member 130 to the surface of the susceptor 105. As a result, a bias voltage is applied to the susceptor 105. A heater 135 is embedded in the substrate 110, and a heater source 145 is connected to the heater 135 via a high frequency cut filter F. As the heater 135, for example, a sheath heater or a planar heater is used. The AC power output from the heater source 145 is applied to the heater 135, whereby the susceptor 105 is heated. A temperature sensor 150 is attached to the inside of the base material, and the inside of the susceptor 105 is maintained at a high temperature of about 200 to 450 ° C. by the control of the temperature controller 155 according to the sensor value. A high frequency cut filter F is provided between the temperature sensor 150 and the temperature controller 155.

  The connecting portion 175a connected to the support 120 and the bottom surface of the processing container 100 are connected by a bellows 175b, so that the vacuum region in the processing container can be changed to the atmospheric region outside the container or in the support 120. Shut off from the atmospheric space S1 and the atmospheric space S2 in the matching box 185. A shield spiral 195 a is provided on the contact surface between the connecting portion 175 a and the matching box 185. The conductive member 130 and the susceptor 105 are sealed with a metal seal 195b. Instead of the sealing member 195b, sealing may be performed by welding, or an O-ring may be used if the temperature is low at 300 ° C. or lower. An O-ring 195d is disposed at the connecting portion of the bellows 175b.

  A plurality of through-holes 160 pass through the susceptor 105. A lift pin 165 and a lifting mechanism 170 that lifts and lowers the lift pin 165 are provided below the through-hole 160. Lift pins 165 are lifted by the lifting mechanism 170 and pass through the through-hole 160 to support the substrate G. Thereby, the board | substrate G is mounted on a susceptor, or is conveyed from on a susceptor. A gas discharge pipe 180 is provided at the bottom of the processing container 100, and the gas in the processing container 100 is discharged using a vacuum pump (not shown) provided outside the processing container 100.

  Dielectric plates 305, metal electrodes 310, and metal covers 320 are regularly arranged on the ceiling surface of the processing container 100. A side cover 350 is provided around the metal electrode 310 and the metal cover 320. The dielectric plate 305, the metal electrode 310, and the metal cover 320 are substantially square plates with slightly rounded corners. In addition, a rhombus may be sufficient. In this specification, the metal electrode 310 refers to a flat plate provided adjacent to the dielectric plate 305 so that the dielectric plate 305 is substantially uniformly exposed from the outer edge of the metal electrode 310. As a result, the dielectric plate 305 is sandwiched between the inner wall of the lid 300 and the metal electrode 310. The metal electrode 310 is electrically connected to the inner wall of the processing container 100.

  The eight dielectric plates 305 and the metal electrodes 310 are arranged at an equal pitch at a position inclined by approximately 45 ° with respect to the substrate G and the processing container 100. The pitch is determined such that the diagonal length of one dielectric plate 305 is 0.9 times or more the distance between the centers of adjacent dielectric plates 305. Thereby, the slightly cut corners of the dielectric plate 305 are arranged adjacent to each other.

  The metal cover 310 and the metal cover 320 are thicker by the thickness of the dielectric plate 305. According to such a shape, the height of the ceiling surface becomes substantially equal, and at the same time, the portions where the dielectric plate 305 is exposed and the shape of the screw holes in the vicinity thereof all have substantially the same pattern. The dielectric plate 305 is made of alumina, and the metal electrode 310, the metal cover 320, and the side cover 350 are made of an aluminum alloy.

  The dielectric plate 305 and the metal electrode 310 are supported on the lid 300 by screws 325. Similarly, the metal cover 320 and the side cover 350 are attached to the main body portion of the lid 300 with screws 325. Between the upper lid body 300a and the lower lid body 300b, there is provided a main gas flow path 330 formed in a lattice shape in a direction perpendicular to the paper surface. The main gas flow path 330 divides the gas into a third gas flow path 325 a provided in the plurality of screws 325. A narrow tube 335 that narrows the flow path is fitted into the inlet of the third gas flow path 325a. The thin tube 335 is made of ceramics or metal. A first gas channel 310 a is provided between the metal electrode 310 and the dielectric plate 305. Second gas flow paths 320 a 1 and 320 a 2 are also provided between the metal cover 320 and the dielectric plate 305 and between the side cover 350 and the dielectric plate 305. The front end surface of the screw 325 is flush with the lower surfaces of the metal electrode 310, the metal cover 320, and the side cover 350 so as not to disturb the plasma distribution. The first gas discharge holes 345a opened in the metal electrode 310 and the second gas discharge holes 345b1 and 345b2 opened in the metal cover 320 and the side cover 350 are arranged at an equal pitch.

  The gas output from the gas supply source 700 passes through the third gas channel 325 a (branch gas channel) from the main gas channel 330, and the first gas channel 310 a and the metal cover 320 in the metal electrode 310. The first gas discharge hole 345a and the second gas discharge holes 345b1 and 345b2 are supplied to the processing chamber through the second gas flow paths 320a1 and 320a2 in the side cover 350. An O-ring 220 is provided on the contact surface between the lower lid 300 b and the dielectric plate 305 in the vicinity of the outer periphery of the first coaxial waveguide 610, and the atmosphere in the first coaxial waveguide 610 is placed inside the processing container 100. It is designed not to enter.

  The refrigerant supply source 705 is connected to the refrigerant pipe 710 inside the lid, and the refrigerant supplied from the refrigerant supply source 705 circulates in the refrigerant pipe 710 inside the lid so that the processing container 100 is brought to a desired temperature. To keep. A refrigerant pipe 715 passes through the inner conductor 640a of the fourth coaxial waveguide in the longitudinal direction. Heating of the internal conductor 640a is suppressed by passing the coolant through this flow path.

  An inner conductor 610a is inserted into the outer conductor 610b of the first coaxial waveguide formed by digging the lid 300. Similarly, the inner conductors 620a to 640a of the second to fourth coaxial waveguides are inserted into the outer conductors 620b to 640b of the second to fourth coaxial waveguides formed by digging in the same manner, and the upper part thereof is a lid cover. It is covered with 660. The inner conductor of each coaxial tube is made of copper with good thermal conductivity.

  The surface of the dielectric plate 305 is covered with a metal film 305a except for a portion where the microwave is incident on the dielectric plate 305 from the first coaxial waveguide 610 and a portion where the microwave is emitted from the dielectric plate 305. Yes. Accordingly, the propagation of the microwave is not disturbed by the gap generated between the dielectric plate 305 and the adjacent member, and the microwave can be stably guided into the processing container.

As a result, the microwave emitted from the dielectric plate 305 propagates on the surfaces of the metal electrode 310, the metal cover 320, and the side cover 350 while distributing the power in half as a surface wave. Hereinafter, the surface wave propagating between the metal surface on the inner surface of the processing container and the plasma is referred to as a conductor surface wave (metal surface wave). As a result, the conductor surface wave propagates to the entire ceiling surface, and uniform plasma is stably generated below the ceiling surface of the plasma processing apparatus 10 according to the present embodiment. Is given. As an example of the plasma treatment, there is a film formation of microcrystal, amorphous silicon, SiO ₂ , or SiN.

(Internal structure of susceptor)
Next, the internal configuration of the susceptor 105 will be described with reference to FIG. As described above, a plurality of clad materials are used for the base material 110 of the susceptor 105. As shown in FIG. 3A, the clad material is manufactured by stacking nickel (Ni) plates, which are mixed materials, on titanium (Ti), which is a base material, with an interval between them, and an explosive thereon. Set Bmp. As shown in FIG. 3 (b), the composite material Ni is driven at high speed on the base material surface due to the high energy during the explosion of the explosive Bmp, and the metal liquefied from the collision surface between the base material and the composite material (metal jet) Will occur. The metal jet removes deposits and adsorbed gas on the surface of the base material Ti, and activates the surface of the base material Ti and the surface of the composite material Ni. When this is crimped, the contact portion between the base material Ti and the composite material Ni is attracted and joined by the atomic force of both metals. Explosive pressure bonding is performed instantaneously, so it is cold pressure bonding, and the joint surface of the base material Ti and the material Ni is rippled Pa as shown in FIG. 3C, and Kalman vortex Pb is generated in some places. ing.

  In the clad material manufactured in this way, the base material and the composite material are firmly bonded. Therefore, when a clad material is used for the susceptor 105, the mechanical strength of the susceptor 105 can be increased. In particular, with the recent increase in size of the substrate G, the susceptor 105 needs to be increased in size. At present, the susceptor 105 must be enlarged in accordance with the substrate sizes of G8 and G10. Therefore, for example, in a substrate having a substrate size of 3000 mm × 3000 mm, the size of the susceptor 105 needs to be about 3100 mm × 3100 mm. If this is attempted to be realized with carbon, for example, the strength of carbon is weak, so that the substrate is warped and the mechanical strength as a susceptor cannot be maintained. On the other hand, it is also conceivable that a plurality of carbons are bonded to form a base material to cope with a large size susceptor. However, there is a limit to the increase in the size of the susceptor 105 using carbon, such as generation of dust at the bonded portion and the inability to maintain mechanical strength at the bonded surface. On the other hand, according to the present embodiment, as described above, the mechanical strength of the susceptor 105 can be increased by using the clad material of titanium and aluminum or nickel, and the susceptor 105 can be flexibly accommodated. .

  Titanium has a low thermal diffusivity. For this reason, the heater 135 which is a heating element is disposed at the center of the base 110. Moreover, even if the thickness of the two clad members sandwiching the heater 135 is the same or different, they are contained within 2 mm which is the thickness of the heater 135.

  Next, a method for manufacturing a susceptor using a plurality of clad materials will be described with reference to FIG. The base material 110 is formed on a rectangle using four clad materials. As shown in FIG. 4A, first, the two clad materials KA and KB serving as the central portion of the base material 110 are joined. The clad materials KA and KB are arranged such that the nickel base material side is on the surface side of the susceptor with the base material side of titanium in a state where the heater 135 is sandwiched therebetween. In this state, screws S are inserted into a plurality of screw holes provided on the clad material KB side, and the clad materials KA and KB are screwed.

  Next, as shown in FIG. 4B, nickel of the same material as the composite material is embedded in the screw hole in which the screw S is inserted, and is joined to the nickel of the composite material of the clad material KB by welding. Further, the side portions of the base materials of the clad materials KA and KB are scraped off by the thickness of the base material. As shown in FIG. 4 (c), the base material of the clad material KC, KD is inserted into the cut portion, and the clad material KA, KB is screwed with a plurality of screws S in the same manner as described above. Is done. Finally, nickel of the same material as the composite material is embedded in the screw hole in which the screw S is inserted, and is joined to the nickel of the composite material of the clad materials KC and KD by welding. The nickel of the clad materials KA and KB and the nickel of the clad materials KC and KD are also welded. In this way, as shown in FIG. 2, the base material 110 is formed by using a plurality of clad materials and bonding the clad materials so that the base material 110a is covered with the composite material 110b. In addition, joining of each clad material is performed by electron beam welding (EBW: Electron Beam Welding). When the composite material is aluminum, Friction Stir Welding (FSW) can be used instead of electron beam welding (EBW). When nickel is used as the compound material, the friction stir welding (FSW) cannot be used because nickel has a high melting point.

  The thickness of the composite material 110b is preferably 1/10 to 3/2 times the thickness of the base material 110a. For example, when performing electron beam welding (EBW), when the beam reaches the base material, an alloy layer is formed at the interface between the composite material and the base material, causing cracks. Therefore, the electron beam welding must be performed within the thickness range of the composite material. The minimum thickness of the composite material required for electron beam welding is 3 mm. It is preferable that a margin for preventing the formation of the alloy layer is 1 mm, and the thickness of the composite material of one clad material is set to 4 mm.

  Decreasing the overall thickness of the susceptor reduces the weight, which is advantageous for thermal expansion, reduces the risk of deformation due to thermal expansion, and reduces the cost. However, in terms of temperature distribution, the overall thickness of the susceptor must be increased to some extent. There is. Considering these, the thickness of the susceptor is designed to be 30 mm to 40 mm. In the present embodiment, the thickness of one clad material 110b is 4 mm, and the total thickness of two clad materials is 30 mm. Accordingly, the thickness of the base material is 11 mm (= 15−4) with respect to the thickness of one clad material of 15 mm. For example, when the total thickness of two clad materials is 40 mm, the thickness of the base material is 16 mm (= 20−4) with respect to the thickness of 20 mm of one clad material.

  Consider the ratio between the thickness of the composite material and the thickness of the base material. For example, considering the Young's modulus ε (= σ: stress / E: strain), titanium is 1.5 times that of aluminum and ½ times that of nickel. From this, when aluminum is used as the composite material, the composite material can be thicker than the base material, and the thickness of the composite material can be up to 1.5 times the thickness of the base material.

  Next, consider how thin the composite can be with respect to the base material. It takes about 2 hours to raise the temperature of the susceptor to 450 ° C. with a general power supply. When the thickness of the base material and the composite material constituting the susceptor increases, naturally, it is necessary to increase the electric power required for the temperature increase or lengthen the temperature increase time. In addition, the responsiveness during operation (in process) also deteriorates. For example, when the thickness of the susceptor is about 90 mm, the temperature rise and the responsiveness are deteriorated, and the demerit is great for the mechanical strength and the uniformity of the internal temperature. Considering this, it is preferable that the thickness of the composite material is thin. However, the optimization of the total thickness of the susceptor 105 includes the following: temperature distribution (thicker is more advantageous: particularly thicker is more advantageous), responsiveness (thin is more advantageous), high-temperature strength (thicker is more advantageous), weight ( It is necessary to determine in consideration of the lighter the thinner one, the better the welding strength (the thicker the material is, the better) and the thermal expansion (the thinner the material is, the better). As a result of considering these matters, the inventors concluded that the thickness of the composite material is preferably 1/10 or more of the thickness of the base material. In this case, the thickness of the composite material may be about 1 mm, but welding is possible with the friction stir welding FSW.

The average linear thermal expansion coefficient of titanium is 9.6 × ^{10 -6} /K~10.0×10 -6 / K when 200 ° C. to 500 ° C., an average line of the average linear thermal expansion coefficient slightly nickel aluminum It is smaller than the thermal expansion coefficient and close to the average linear thermal expansion coefficient of alumina. Therefore, when titanium is used as a base material, aluminum or nickel is used as a composite material, and alumina is sprayed onto the aluminum or nickel composite material, the difference in thermal expansion between the sprayed alumina and the susceptor can be reduced. As a result, it is possible to create a structure in which stress is not easily concentrated even when the susceptor is heated from a room temperature of 20 ° C. to a process temperature of 450 ° C. or cooled. Thereby, it can suppress that the sprayed alumina cracks or peels off and causes a contamination. Furthermore, as described above, by using a clad material in which the base material and the composite material are firmly joined at the joining surface, peeling and cracking can be further prevented and the mechanical strength of the susceptor can be increased.

  Moreover, the susceptor 105 according to the present embodiment is also excellent in corrosion resistance. For example, when aluminum is sprayed on titanium instead of using a clad material of titanium and nickel, aluminum becomes porous, and therefore, there is a possibility that the aluminum is passed through a gas used for plasma processing and the titanium is corroded. Moreover, when aluminum is welded to titanium, the problem that aluminum peels from titanium due to corrosion of titanium remains. However, in the susceptor 105 according to the present invention, the base material made of titanium is covered with a composite material made of aluminum or nickel and is not exposed to the outside. For this reason, plasma does not contact with titanium which is a base material. In addition, in the clad material, aluminum or nickel as a composite material is not porous like spraying. Therefore, aluminum or nickel of the composite material is excellent in plasma resistance and gas resistance. Thus, the gas does not corrode titanium through aluminum or nickel. For these reasons, according to the present embodiment, the susceptor 105 having excellent corrosion resistance can be constructed.

  Further, the high frequency current output from the high frequency power supply 140 flows through the surface layer of nickel or aluminum of the susceptor 105. At that time, if the gap between the support 120 and the alumina insulator 115 is controlled to 0.5 mm or less, abnormal discharge can be prevented from occurring in the gap. However, in the conventional apparatus shown in FIG. 9, the gap α between the alumina insulator 910 and the support 990 is 0.5 mm or more because the thermal expansion difference between the aluminum of the substrate 110 and the alumina forming the periphery of the aluminum is large. As a result, plasma may enter the gap α and abnormal discharge may occur.

  On the other hand, the coefficient of linear thermal expansion of titanium is smaller than that of aluminum or nickel. Therefore, according to the susceptor 105 according to the present embodiment, the gap between the alumina insulator 115 and the support 120 can be managed to be 0.5 mm or less. As a result, it is possible to prevent abnormal discharge from occurring in the gap.

  Returning to FIG. 2, the description of the internal configuration of the susceptor will be continued. The clad material 110 is thermally sprayed with alumina having a thickness of about 100 μm to 400 μm, whereby an alumina insulator 115 is formed. Thereby, the board | substrate G can be warmed with the radiant heat of an alumina. Thus, the corrosion resistance and emissivity of the susceptor 105 are enhanced by spraying alumina or yttria on the surface of the substrate 110 or performing anodizing. Further, in the case of a clad material formed of titanium and nickel, since the difference in thermal expansion between titanium and nickel is small, it is effective for preventing the substrate 110 from warping.

  In this way, the susceptor 105 of this embodiment is formed adjacent to the titanium, nickel, and alumina in this order. The reason why alumina is not directly sprayed on titanium is that although alumina has corrosion resistance, the alumina insulator 115 is formed in a porous shape by spraying, so when alumina is directly sprayed on titanium, gas is passed between the pores of the porous, This is because the titanium is corroded. In contrast, in the susceptor 105 according to the present embodiment, by covering titanium with nickel or aluminum, even if gas is passed between porous pores of alumina spraying, the internal titanium is corroded due to the corrosion resistance of nickel. Guarded from.

  Instead of spraying alumina on the substrate 110, yttria may be sprayed. However, yttria is suitable for a process that does not use a fluorine-based gas because there is a risk of being weakly peeled off by the fluorine-based gas.

(Lift pin through hole)
Next, the lift pin through-hole 160 provided in the susceptor 105 will be described with reference to FIGS. As shown in FIG. 2, the substrate 110 is provided with a plurality of through holes 160. As described above, the lift pins 165 pass through the through hole 160 and come into contact with the back surface of the substrate G to lift the substrate G. If the titanium of the base material 110a is exposed on the inner wall surface of the through hole 160, the plasma may be corroded or cause abnormal discharge when the plasma enters the through hole 160. Therefore, as shown in FIG. 5A, a nickel sleeve 110 c (pipe-like tube) is fitted into the through-hole 160 of the base 110. The sleeve 110c and the clad material mixture 110b are welded together. Further, in order to improve the slidability, an alumina or zirconia sleeve 110h is further fitted inside the nickel sleeve 110c. The sleeve 110c and the clad material mixture 110b are joined by welding.

In order to set the temperature of the substrate G on the susceptor to about 350 ° C., the heater 135 needs to raise the temperature of the susceptor 105 to about 450 ° C. When heating, when aluminum or nickel is used for the base material 110, these materials have a large coefficient of linear expansion, so that the expansion and contraction is large. For example, when the temperature is 20 ° C. to 350 ° C., the average linear thermal expansion coefficient of aluminum is 25 × 10 ⁻⁶ / K, and the average linear thermal expansion coefficient of nickel is about 15 × 10 ⁻⁶ / K. On the other hand, the average linear thermal expansion coefficient of alumina is 7.8 × 10 ⁻⁶ / K. Thus, the linear thermal expansion coefficient of aluminum or nickel is two to three times larger than the linear thermal expansion coefficient of alumina. Since the length from the center of the base material 905 to the end is 1500 mm, in this state, when the temperature of the base material 905 made of aluminum is increased from 25 ° C. of the room temperature to 450 ° C. of the process temperature, the center of the base material 905 is The length to the end extends about 16 mm. On the other hand, the linear thermal expansion coefficient of glass is 3.8 × 10 ⁻⁶ / K when it is 200 ° C. to 300 ° C. Therefore, the elongation of the glass substrate G when the temperature of the heater 135 is set to 450 ° C. is about 2 mm. As a result, the lift pin 165 penetrating through the through-hole 160 protrudes outward from the side portion of the substrate G and does not contact the back surface of the substrate G, so that the substrate G may not be lifted.

  However, according to this embodiment, since the base material 110 only needs to be formed of a clad material of titanium and nickel or aluminum, positioning errors of the lift pins 165 for transporting the substrate G due to low thermal expansion of titanium are reduced. can do. In FIG. 5A, a nickel sleeve 110c and an alumina or zirconia sleeve 110h are fitted into the through-hole 160. Thereby, since titanium is not exposed to the inner wall of the through-hole 160, corrosion of titanium by plasma can be prevented and occurrence of abnormal discharge can be prevented.

  However, in FIG. 5A, a difference in thermal expansion occurs in the height direction between the sleeves 110 c and 110 h and the base material 110 made of a combination of nickel and titanium adhered to these sleeves. On the other hand, as shown in FIG. 5B, two ring-shaped members 110d and 110e formed of nickel at both ends of the through-hole 160 are joined to the clad material 110b, respectively. Both ends of the bellows 110f formed by the above are joined to the periphery of the openings of the two ring-shaped members 110d and 110e. There is a space between the base material 110a of the clad material and the bellows 110f. Thereby, the titanium of the clad base material 110a is not exposed to the plasma side by the ring-shaped members 110d and 110e and the bellows 110f. As a result, it is possible to prevent the titanium from being corroded by the plasma and to absorb the thermal expansion of the base material 110a by the bellows 110f.

  As described above, according to the present embodiment, by forming the base material 110 using a plurality of clad materials formed of nickel and titanium, low thermal expansion, high mechanical strength, plasma resistance, gas A susceptor 105 having excellent corrosion resistance such as resistance can be provided. At that time, mainly low thermal expansion and mechanical strength are secured by titanium, and corrosion resistance is secured by nickel.

  The thickness of the composite material 110b is preferably 1/10 to 3/2 times the thickness of the base material 110a. For example, when performing electron beam welding (EBW), when the beam reaches the base material, an alloy layer is formed at the interface between the composite material and the base material, causing cracks. Therefore, the electron beam welding must be performed within the thickness range of the composite material. The minimum thickness of the composite material required for electron beam welding is 3 mm. It is preferable that a margin for preventing the formation of the alloy layer is 1 mm, and the thickness of the composite material of one clad material is set to 4 mm.

  Decreasing the overall thickness of the susceptor reduces the weight, which is advantageous for thermal expansion, reduces the risk of deformation due to thermal expansion, and reduces the cost. However, in terms of temperature distribution, the overall thickness of the susceptor must be increased to some extent. There is. Considering these, the thickness of the susceptor is designed to be 30 mm to 40 mm. In the present embodiment, the thickness of one clad material 110b is 4 mm, and the total thickness of two clad materials is 30 mm. Accordingly, the thickness of the base material is 11 mm (= 15−4) with respect to the thickness of one clad material of 15 mm. For example, when the total thickness of two clad materials is 40 mm, the thickness of the base material is 16 mm (= 20−4) with respect to the thickness of 20 mm of one clad material.

  Consider the ratio between the thickness of the composite material and the thickness of the base material. For example, considering the Young's modulus ε (= σ: stress / E: strain), titanium is 1.5 times that of aluminum and ½ times that of nickel. From this, when aluminum is used as the composite material, the composite material can be thicker than the base material, and the thickness of the composite material can be up to 1.5 times the thickness of the base material.

  Next, consider how thin the composite can be with respect to the base material. It takes about 2 hours to raise the temperature of the susceptor to 450 ° C. with a general power supply. When the thickness of the base material and the composite material constituting the susceptor increases, naturally, it is necessary to increase the electric power required for the temperature increase or lengthen the temperature increase time. In addition, the responsiveness during operation (in process) also deteriorates. For example, when the thickness of the susceptor is about 90 mm, the temperature rise and the responsiveness are deteriorated, and the demerit is great for the mechanical strength and the uniformity of the internal temperature. Considering this, it is preferable that the thickness of the composite material is thin. However, the optimization of the total thickness of the susceptor 105 includes the following: temperature distribution (thicker is more advantageous: particularly thicker is more advantageous), responsiveness (thin is more advantageous), high-temperature strength (thicker is more advantageous), weight ( It is necessary to determine in consideration of the lighter the thinner one, the better the welding strength (the thicker the material is, the better) and the thermal expansion (the thinner the material is, the better). As a result of considering these matters, the inventors concluded that the thickness of the composite material is preferably 1/10 or more of the thickness of the base material. In this case, the thickness of the composite material may be about 1 mm, but welding is possible with the friction stir welding FSW.

  In the conventional plasma processing apparatus, as shown in FIG. 9, the power feeding rod 915 passes through the insulating material 985 embedded in the base 905 and is connected to the electrode at the power feeding point 915a. After the surface of the substrate 905 is sprayed with aluminum, alumina is sprayed thereon to form an alumina spray 910, and tungsten serving as an electrode is sprayed thereon, and then alumina is sprayed again thereon. With such a four-layer spraying structure, the tungsten electrode is formed in a porous shape. For this reason, the adhesion between the electrode rod 915 and the electrode is poor. Therefore, when high-frequency current flows on the surface of the base material, power loss may occur at the feeding point 915a to generate heat or abnormal discharge may occur.

  However, in the susceptor 105 according to the present embodiment, the high frequency power output from the high frequency power supply 140 propagates through the surface of the conductive member 130 to the surface of the susceptor 105. As a result, the power is not lost at the feeding point 915a and heat is not generated as in the conventional case, and abnormal discharge does not occur. As a result, according to the susceptor 105 according to the present embodiment, a lower electrode having excellent electrical characteristics and high power supply efficiency can be realized.

  In the above-described method for manufacturing the base material 110 from a plurality of clad materials, screws S are used to join the plurality of clad materials as shown in the upper part of FIG. Instead, as shown in the lower part of FIG. 6, when joining a plurality of clad materials, the joining through-holes 190 are provided at positions where they communicate with each other, and the communicating through-holes 190 are adjacent to each other. You may block | close with the boss | hub 110g which consists of the same material of the same thickness as a base material and compound material. That is, the boss 110g has a structure in which titanium having the same material and thickness as the base material is sandwiched between nickel having the same material and thickness as the composite material. The nickel portion of the boss 110g and the composite material 110b are welded. The boss 110g is an example of a closing member that closes the joining through hole. Further, when joining a plurality of clad materials, both of the joining methods shown in the upper and lower parts of FIG. 6 may be used.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, the plasma processing apparatus according to the present invention can be applied to all plasma processing apparatuses such as a parallel plate type plasma processing apparatus (capacitive coupled plasma), ICP (Inductive Coupled Plasma), and ECR (Electron Cyclotron Resonance). In this case, the plasma source may be a high-frequency power source, a microwave source, or the like.

  Further, for example, the plasma processing apparatus according to the present invention may be a CMEP plasma processing apparatus (CMEP: Cellular Microwave Exclusion Plasma) shown in FIG.

  The CMEP plasma processing apparatus 10 includes a processing container 100 and a lid 200. A susceptor 105 for placing the substrate G is provided in the center of the processing container. A clad material is used for the base material 110 of the susceptor 105. Alumina and yttria are sprayed on the surface of the substrate 110.

The lid 200 is provided with six rectangular waveguides 205, a slot antenna 210, and a plurality of dielectric plates 215. The six rectangular waveguides 205 have a rectangular cross-sectional shape, and are arranged at equal intervals in the lid 200. The inside of each rectangular waveguide 205 is filled with a dielectric member 205a such as fluororesin (for example, Teflon (registered trademark)), alumina (Al ₂ O ₃ ), or quartz. Each rectangular waveguide 205 is connected to a microwave source (not shown).

The slot antenna 210 is a metal such as aluminum and is formed of a nonmagnetic material. In the slot antenna 210, slots 210 a (openings) are opened at equal intervals on the lower surface of each rectangular waveguide 205. Each slot 210a is filled with a dielectric member 210a1 such as fluororesin, alumina (Al ₂ O ₃ ), or quartz. Each dielectric plate 215 is formed in a tile shape and is supported by a grid-like metal beam 220. Each dielectric plate 215 is formed using a dielectric material such as quartz glass, AlN, Al ₂ O ₃ , sapphire, SiN, or ceramics.

  With the configuration described above, for example, 2.45 GHz microwave output from the microwave source is transmitted through each dielectric plate 215 from each rectangular waveguide 205 and each slot 210a and radiated to the processing chamber. . The emitted microwaves excite the gas supplied from the gas supply source 700, whereby the large-sized substrate G placed on the susceptor 105 is subjected to desired plasma processing by the generated plasma.

  The plasma processing apparatus according to the present invention can execute various processes for finely processing an object to be processed using plasma, such as a film forming process, a diffusion process, an etching process, an ashing process, and a plasma doping process.

  In addition to the glass substrate, a circular silicon wafer or a square SOI (Silicon On Insulator) substrate can be placed on the susceptor of the plasma processing apparatus according to the present invention.

DESCRIPTION OF SYMBOLS 10 Plasma processing apparatus 100 Processing container 105 Susceptor 110 Base material 110a Base material 110b Compound material 110c Sleeve 110d, e-ring 110f, 175b Bellows 110g Boss 115 Alumina insulator 120 Support body 130 Conductive member 135 Heater 140 High frequency power supply 145 Heater source 160 Through-hole 165 Lift pin KA, KB, KC, KD Clad material S Screw

Claims (8)

A susceptor provided inside the plasma processing apparatus,
The susceptor has a base material on which an object to be processed is placed,
The base material is formed by using a plurality of clad materials formed from a titanium base material and a nickel or aluminum composite material, and joining the plurality of clad materials so that the base material is covered with the composite material. Susceptor to be.   The susceptor according to claim 1, wherein a thickness of the composite material is 1/10 times to 3/2 times a thickness of the base material.   The susceptor according to claim 1, wherein either alumina or yttria is sprayed on the composite material exposed on the surface of the base material.   The susceptor according to any one of claims 1 to 3, wherein the base material is provided with a through-hole through which a lift pin passes, and a pipe-like tube formed of nickel is fitted into the through-hole. .   The base is provided with a through-hole through which the lift pin passes, and two ring-shaped members made of nickel are joined to the openings at both ends of the through-hole, respectively, and a bellows made of nickel The susceptor according to any one of claims 1 to 3, wherein both ends of the rim are joined to the two ring-shaped members.   The susceptor according to claim 1, wherein the plurality of clad members are screwed, and screw holes are filled with nickel.   The plurality of clad materials have through holes for joining at positions where the clad materials are joined to each other, and the communicated through holes are the same as the base material and the composite material of the joined clad materials. The susceptor according to claim 1, wherein the susceptor is closed by a blocking member made of the same material as the thickness. A plasma processing apparatus comprising: a processing chamber that excites a gas by energy of a plasma source to perform plasma processing on an object to be processed; and a susceptor provided inside the processing chamber,
The susceptor has a base material on which an object to be processed is placed,
The base material is formed by using a plurality of clad materials formed from a titanium base material and a nickel or aluminum composite material, and joining the plurality of clad materials so that the base material is covered with the composite material. Plasma processing apparatus.

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