JP2005057234A - Electrostatic chuck - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic chuck inhibiting a rise in temperature by improving the cooling properties of a mounting surface, preventing the occurrence of cracks and dielectric breakdown of an insulating film due to a difference in thermal expansion from a substrate, and having satisfactory wafer attracting/disengaging properties. <P>SOLUTION: There are provided an insulating layer 3 on one main surface of a conductive substrate 2, electrodes for attracting 4a and 4b on its top surface, and an insulating film 5 in such a manner as to cover the electrodes for attracting 4a and 4b. With its top surface as a mounting surface 5a mounting a wafer W, the total thickness of the insulating layer 3 and the insulating film 5 is 20 to 2000μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an etching process for finely processing a semiconductor wafer (hereinafter referred to as a wafer) and liquid crystal glass, a film forming process for forming a thin film, and an exposure for exposing a photoresist film in a semiconductor manufacturing process and a liquid crystal manufacturing process. The present invention relates to an electrostatic chuck that holds a wafer or liquid crystal glass in a processing step or the like.

  Conventionally, in a semiconductor manufacturing process, in order to hold a wafer in an etching process for performing fine processing on a wafer, a film forming process for forming a thin film, or an exposure processing process for exposing a photoresist film. An electrostatic chuck that electrostatically attracts the wafer is used.

  As shown in FIG. 6, the electrostatic chuck includes a pair of suction electrodes 53 on the upper surface of the ceramic base 54 and a power supply terminal 58 for energizing the suction electrodes 53, and is insulated so as to cover the suction electrodes 53. A film 52 is formed, and the upper surface of the insulating film 52 is a mounting surface 52a on which the wafer is placed.

  The electrostatic chuck 51 is an object holding device that uses electrostatic coulomb force, and an insulating film 52 having a dielectric constant ε is formed with a thickness r, a wafer is placed on the mounting surface 52a, and a voltage of V volts is applied to the suction electrode 53. Is applied, V / 2 volts, which is half the voltage, is applied between the wafer W and the adsorption electrode 53. The voltage causes an attracting force F that attracts the wafer W.

F = (ε / 2) × (V ² / 4r ² )
The adsorption force F, which is an electrostatic force that is a holding force for holding an object, increases as the thickness r of the insulating film 52 decreases, and increases as the voltage V increases. As the voltage V is increased, the attractive force F increases. However, if the voltage V is increased too much, the insulation of the insulating film 52 is destroyed. Further, if there is a void such as a pinhole in the insulating film 52, the insulation is destroyed. Therefore, the surface of the insulating film 52 that holds the object is required to be smooth and free from pinholes.

  By the way, as shown in Patent Document 1, a normal electrostatic chuck uses a metal such as aluminum as an electrode, and an insulating film covering the same is provided with an organic film such as glass or bakelite, acrylic or epoxy. Has been. However, these insulating films are not only problematic in terms of heat resistance, wear resistance, chemical resistance, etc., but because of their low hardness, wear powder is easily generated during use and adheres to the semiconductor wafer. There is also a problem in terms of cleanliness, such as being liable to adversely affect the wafer.

  Moreover, although the electrostatic chuck which used the thermal spray-molded ceramic film | membrane as the insulating film 25 like FIG. 4 is described in patent document 2, there existed a problem that cooling efficiency was bad.

  Patent Document 3 describes a method in which an adsorption electrode is formed on the main surface of a ceramic substrate, and an insulating film having a thickness of several μm is formed on the entire main surface of the ceramic substrate by sputtering, ion plating, or vacuum deposition. Has been.

  Further, as required characteristics of the electrostatic chuck used in the etching process, the process temperature varies depending on the plasma resistance in the halogen corrosive gas of the process gas and the cleaning gas, and the film type to be etched. What can be used in a range is also required.

  Further, with the expansion of the memory capacity of the VLSI, the fine processing is progressing more and more, and the processes that require plasma resistance are expanding. In particular, halogen-based corrosive gases such as chlorine-based gases and fluorine-based gases are frequently used as etching gases and cleaning gases. In cleaning, wafer rescreening is performed in which cleaning is performed without placing a dummy wafer on the wafer mounting surface, and plasma resistance of the wafer mounting surface may be strongly required.

  In addition, depending on the film type on the wafer to be etched, the electrostatic chuck must have a wide use temperature range and must be durable over a wide temperature range. For electrostatic chucks, an aluminum alloy is used as the conductive substrate and the surface is made of an alumina sprayed film, or an aluminum alloy is used as the conductive substrate to form an anodized aluminum film on the surface. Thus, electrostatic chucks that also have plasma resistance have been disclosed. However, when the temperature rises, there is a problem that cracks occur due to the difference in thermal expansion between the aluminum base and the insulating film. As a countermeasure for this, as in Patent Document 4, in consideration of the thermal expansion coefficient of the conductive base 23 made of ceramic and metal, an alumina sprayed film 25 is used as an insulating film so that cracks do not occur even when used in a wide temperature range. there were.

  In Patent Document 5, an aluminum anodic oxide film is formed on the surface of an aluminum alloy substrate as a conductive substrate, and an amorphous Al oxide having excellent plasma resistance is formed on the surface in an amount of 0.1 to 10 μm. There was a thing.

Further, in Patent Document 6, there is one in which an adsorption electrode is built in a ceramic, but it is integrated by being joined to a conductive substrate having a cooling function by a silicone adhesive or the like.
JP 59-92782 A JP 58-123381 A JP-A-4-49879 JP-A-11-265930 JP-A-8-288376 JP-A-4-287344

  In the electrostatic chuck 21 of Patent Document 4, since the conductive base 23 made of ceramic and metal serves as a single electrode for adsorption, electrical connection with the wafer W is necessary, and the wafer W is adsorbed spontaneously. A bipolar electrode for adsorption could not be provided.

  Further, it is insufficient to remove the heat of the wafer W heated from the plasma atmosphere or the like from the mounting surface, the temperature of the wafer W rises, the temperature difference in the wafer W surface increases, There was a problem that processing was not possible.

  In addition, the insulating film of the electrostatic chuck described in Patent Document 3 and Patent Document 5 is manufactured by sputtering or CVD, and the thickness of the insulating film is limited to several μm or less. There was a risk that the film would break down.

  In Patent Document 5, an aluminum anodic oxide film 26 is formed on the surface of an aluminum alloy substrate 24 as shown in FIG. 5, and an amorphous aluminum oxide layer 22 having excellent plasma resistance is formed thereon. However, the insulating film 22 having a thickness of about 10 μm has a problem in that the pinhole generated during the film formation is not filled and the base is affected. On the other hand, when the thickness is about 0.1 to 10 μm, it is eroded immediately under hard plasma conditions, and the practicality is poor. This film has a problem that when a film of 10 μm or more is formed, it is peeled off due to internal stress at the time of film formation.

  Further, since the aluminum alloy substrate 24 is used as the conductive substrate, the thermal expansion coefficients of the aluminum anodic oxide film 26 and the amorphous aluminum oxide layer 22 formed thereon are different. There was a problem that the insulating film 22 would crack at a temperature of.

  In addition, when the volume resistivity of the upper amorphous aluminum oxide film 22 is larger than that of the lower aluminum anodic oxide film, the voltage between the conductive substrate 24 of the electrostatic chuck 21 and the wafer is less than the amorphous aluminum oxide film. The amorphous aluminum oxide film 22 sometimes breaks down due to the large addition to the side 22.

  Further, since the volume resistivity of the amorphous aluminum oxide film 22 and the aluminum anodic oxide film 26 are different, it takes time for the adsorption force to rise and become constant even when a voltage is applied. Even if the voltage is turned off, the responsiveness of the adsorption / detachment characteristics such as the adsorption force does not become zero immediately but the residual adsorption force may be deteriorated, and it takes more time than necessary to detach the wafer. However, the process control may be hindered.

  In addition, the electrostatic chuck described in Patent Document 6 has a thickness of the plate-like ceramic body exceeding 2 mm and cannot sufficiently pass the heat of the wafer W, so that the cooling efficiency is poor and the temperature of the wafer W rises. There was a problem.

  As in Patent Document 2 and Patent Document 4, when the alumina sprayed layer is an insulating film, there are many voids in the sprayed film, and the voids are sealed using organic silicon or inorganic silicon. There was a risk that the silicon portion that had been etched was etched with plasma, the withstand voltage was lowered, and the life that could be used as an electrostatic chuck in a short period was short.

  In addition, there is a problem in that the insulating film is scraped by the wafer to generate particles, thereby reducing the processing yield of the wafer.

  An insulating layer is provided on one main surface of the conductive substrate, an adsorption electrode is provided on the upper surface thereof, and an insulating film is provided so as to cover the adsorption electrode, and the upper surface is used as a mounting surface on which a wafer is placed. The total thickness with the film is 20 to 2000 μm.

  Further, the insulating film is formed so as to cover the insulating layer.

  The insulating layer is made of an amorphous ceramic.

  The insulating film is made of a uniform amorphous ceramic made of an oxide and has a thickness of 10 to 100 μm.

  The insulating film contains 1 to 10 atomic% of a rare gas element and has a Vickers hardness of 500 to 1000 HV0.1.

  In addition, the insulating film is mainly composed of any one of aluminum oxide, yttrium oxide, yttrium aluminum oxide, or a rare earth oxide.

  Further, the conductive substrate is composed of any one metal component of aluminum or aluminum alloy and one ceramic component of silicon carbide or aluminum nitride, and the content of the ceramic component is 50 to 90% by mass. It is characterized by.

  Further, a protective film made of an anodized aluminum film or an alumina sprayed film is formed on the surface of the conductive substrate other than the surface on which the insulating film is formed.

  Further, the insulating layer is made of polyimide.

  The insulating layer has a thickness of 5 to 150 μm.

  In addition, it is characterized in that it has convex portions scattered on the surface of the insulating film.

  Further, the volume specific resistance of the convex portion is smaller than the volume specific resistance of the insulating film.

  Moreover, the height of the said convex part is 0.5-5 micrometers, It is characterized by the above-mentioned.

  The electrostatic chuck of the present invention comprises an insulating layer on one main surface of a conductive substrate, an adsorption electrode on its upper surface, and an insulating film so as to cover the adsorption electrode, and a mounting surface on which the wafer is placed. As described above, if the total thickness of the insulating layer and the insulating film is 20 to 2000 μm, there is no temperature change of the mounting surface even when plasma is generated, and no cracks of the insulating film occur. Insulation breakdown can be prevented. Further, an electrostatic chuck having excellent separation characteristics of the wafer W and a large attracting force can be obtained.

  Furthermore, when a protective film is formed, an electrostatic chuck having excellent durability against plasma can be provided.

  In addition, an excellent electrostatic chuck with less generation of particles can be obtained.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 shows a schematic structure as an example of the electrostatic chuck 1 of the present invention. An insulating layer 3 is formed on one main surface of the metal or conductive substrate 2, adsorption electrodes 4 a and 4 b are formed on the upper surface, and an insulating film 5 is formed so as to cover the adsorption electrode 4. The upper surface of the insulating film 5 is used as a mounting surface 5a for attracting the wafer.

  The insulating layer 3 is preferably made of an oxide ceramic such as alumina, or a ceramic such as nitride or carbide. The insulating film 5 may be made of the same composition as the insulating layer 3, but is preferably made of amorphous ceramics.

  When the conductive substrate 2 is made of only metal, it is preferable to select the metal of the conductive substrate 2 in accordance with the thermal expansion of the insulating layer 3 and the insulating film 5. Since many metals have a larger coefficient of thermal expansion than ceramic, the material of the conductive substrate 2 is preferably a metal mainly composed of a low thermal expansion metal such as W, Mo, or Ti.

  Further, when a metal / ceramic composite member is used as the conductive substrate 2, it is preferable to use a composite material in which a porous ceramic body having a three-dimensional stitch structure is used as a skeleton and aluminum or an aluminum alloy is filled in the pores without any gaps. . With such a structure, the thermal expansion coefficients of the insulating layer 3 and the insulating film 5 and the conductive substrate 2 can be made closer.

  Furthermore, a material having a large thermal conductivity of about 160 W / (m · K) is obtained for the conductive substrate 2 described above, and it becomes easy to remove the heat transferred from the atmosphere such as plasma to the wafer W through the conductive substrate 2. preferable.

  The conductive substrate 2 is provided with a flow path 9 through which a cooling medium passes, and the heat of the wafer W can be removed to the outside of the electrostatic chuck 1 through the cooling medium. It became easy to control by temperature.

  Then, the wafer W is placed on the mounting surface 5 a, and a suction voltage of several hundred volts is applied between the suction electrodes 4 from the power supply terminals 6 a and 6 b, and the electrostatic force is applied between the suction electrode 4 and the wafer W. An adsorption force can be developed, and the wafer W can be adsorbed on the mounting surface 5a. Further, when an RF voltage is applied between the conductive substrate 2 and the counter electrode (not shown), plasma can be efficiently generated above the wafer W.

  The electrostatic chuck 1 of the present invention is characterized in that the total thickness of the insulating film 5 and the insulating layer 3 is 20 to 2000 μm. With this thickness, the heat transferred from the wafer W to the mounting surface 5a can be released to the conductive substrate 2. And it can prevent that the temperature rise of the wafer W and the temperature difference in the wafer W surface become large. If the total thickness is less than 20 μm, there is a risk of dielectric breakdown between the adsorption electrode 4 and the conductive substrate 2, and if the total thickness exceeds 2000 μm, the heat of the wafer W may not be sufficiently transmitted to the conductive substrate 2. Because there is. Preferably they are 30 micrometers-500 micrometers, More preferably, they are 50-200 micrometers.

  The thickness t1 of the insulating film 5 is a distance from the upper surface of the adsorption electrode 4 to the upper surface of the mounting surface 5a, and is expressed by an average value of the five distances in a cross section perpendicular to the mounting surface 5a. Can do. In addition, the thickness t2 of the insulating layer 3 was similarly measured by measuring the thickness at five locations in the cross section, and taking the average value. And the value which totaled the thickness t1 of the said insulating film 5a and the thickness t2 of the insulating layer 3 was made into the total thickness.

  Further, the mounting surface 5a can be formed with a recess by a blasting method or the like. A gas supply hole communicating with the recess and penetrating from the back surface of the conductive substrate 2 to the mounting surface 5a can be provided, and gas can be supplied from the gas supply hole to a space formed by the wafer W and the recess. And the heat conductivity between the wafer W and the mounting surface 5a can also be raised.

  The insulating film 5 is preferably made of alumina, nitride, or carbonized ceramic, and its thermal conductivity is preferably 20 W / (m · K) or more. The thickness of the insulating film 5 made of such sintered ceramics is preferably 10 to 1500 μm because the heat of the wafer W can be efficiently released to the conductive substrate 2. Preferably it is 100-1000 micrometers, More preferably, it is 200-500 micrometers. The insulating film 5 having a large thermal conductivity of 50 W / (m · K) or more preferably has a thickness of 200 to 1500 μm. The lower limit of the insulating film 5 can be indicated by the minimum value of the thickness of the insulating film 5 from a cross section perpendicular to the mounting surface 5a and crossing near the diameter.

  The insulating layer 3 made of sintered ceramics preferably has a thickness of 10 μm to 1990 μm. This is because if the thickness of the insulating layer 3 is less than 10 μm, there is a risk that the insulation between the adsorption electrode 4 and the conductive substrate 2 cannot be maintained. This is because if the thickness exceeds 1990 μm, the heat from the mounting surface 5 a may not be sufficiently transmitted to the conductive substrate 2. Such an insulating layer 3 more preferably has a thermal conductivity of 50 W / (m · K) or more.

  The insulating layer 3 can be made of a film having the same composition as that of the insulating film 5 which is close to the thermal expansion coefficient of the conductive substrate 2 and the insulating film 5 and has excellent insulating properties, or borosilicate glass or borate glass.

  The insulating layer 3 can also be composed of amorphous ceramics. Here, the amorphous ceramics refers to those having a basic composition of a ceramic crystal composition such as alumina, alumina yttria oxide material, and nitride material.

  When the insulating layer 3 is made of the same amorphous ceramic composition as the insulating film 5, the thickness is preferably 10 to 100 μm. If the thickness is less than 10 μm, the dielectric breakdown may occur, and if it exceeds 100 μm, the mass productivity is inferior.

  Further, when the general glass composition other than the amorphous ceramic is used as the insulating layer 3, the thickness of the insulating layer 3 is preferably not more than 1990 μm so that heat of the wafer W placed on the mounting surface 5a can be easily transferred. In order to ensure insulation between the conductive substrate 2 and the adsorption electrode 4, it is preferably 10 μm or more. More preferably, it is 20-1000 micrometers, More preferably, it is 50-300 micrometers.

  Moreover, since the insulating layer 3 made of the glass composition is inferior in corrosion resistance in a plasma atmosphere, it is preferable that the insulating film 5 is formed so as to cover the insulating layer 3 as shown in FIG. By forming in this way, the corrosion resistance of the electrostatic chuck 1 can be increased, the reliability of the electrostatic chuck 1 can be improved, and the life of the electrostatic chuck is also extended.

  The insulating film 5 of the present invention is preferably formed from only one layer of the insulating film 5 made of a uniform amorphous ceramic. Since the insulating film 5 has a uniform volume resistivity between the adsorption electrode 4 and the mounting surface 5a, an adsorption force is applied when an electric field is uniformly formed in the insulation film 5 and an adsorption voltage is applied. Develops quickly and has a constant adsorption force. When the applied suction voltage is cut off, the suction force becomes zero immediately and the wafer W can be detached. Thus, the electrostatic chuck 1 having excellent adsorption / detachment characteristics can be obtained.

  The reason why the insulating film 5 is the insulating film 5 made of a uniform amorphous ceramic is considered as follows.

  Insulating films made of crystalline ceramic have crystal lattices that are tightly coupled, so the interstitial distance is unlikely to change due to stress, and if the insulating film made of crystalline ceramic is used as the insulating film of an electrostatic chuck, a conductive substrate Although the function to relieve thermal stress such as internal stress and thermal expansion difference generated in the above insulating film from 2 is poor, the insulating film 5 made of amorphous ceramic can be formed at a low temperature unlike the insulating film made of crystalline ceramic. The interstitial distance changes with respect to stress at a relatively low temperature, and the internal stress can be made smaller than that of an insulating film made of crystalline ceramic. Further, since the insulating film 5 made of amorphous ceramic is amorphous, the atomic arrangement is not periodic, and an atomic level space is easily formed and impurities are easily taken in. Therefore, even if an internal stress is generated due to a difference in thermal expansion between the insulating film 5 made of amorphous ceramic and the conductive substrate 2 or a stress at the time of film formation, the atomic arrangement is irregular and defects at the atomic level. Therefore, the insulating film 5 can be displaced at a low deposition temperature, and the stress applied to the insulating film 5 can be reduced. The insulating film 5 made of amorphous ceramic is deviated from the stoichiometric composition of the corresponding crystal having the same composition. Therefore, defects at the atomic level are easily formed between the insulating film 5 and the conductive substrate 2. It becomes easy to relieve stress.

  The thickness of the insulating film 5 made of the amorphous ceramic is preferably 10 to 100 μm. When the thickness of the insulating film 5 made of amorphous ceramic is less than 10 μm, the insulating film 5 made of amorphous ceramic has an extremely large pinhole or film thickness due to the influence of voids and particles on the surface of the conductive substrate 2. When it is used in plasma, the portion becomes a defect, and the adsorption electrode 4 may be eroded through the insulating film 5, and abnormal discharge or particles due to dielectric breakdown of the insulating film 5 may occur. is there. Therefore, the insulating film 5 needs to have a thickness of at least 10 μm.

  In addition, if the thickness of the insulating film 5 exceeds 100 μm, the time for forming the insulating film 5 made of amorphous ceramic is several tens of hours or more, and the mass productivity is poor, and the internal stress becomes too large. There is a risk of peeling from the electrode 4, the insulating layer 3, and the conductive substrate 2. Preferably, the thickness of the insulating film 5 is 30 to 70 μm, and more preferably 40 to 60 μm.

  In the present invention, the thickness of the insulating film 5 is 10 μm or more means that the minimum thickness of the insulating film 5 on the conductive substrate 2 is 10 μm or more, and the thickness of 100 μm or less is the insulation on the conductive substrate 2. The average thickness of the film 5 is 100 μm or less. The average thickness is a value obtained by measuring the film thickness in an area obtained by dividing the insulating film 5 into five equal parts and averaging the film thicknesses at five points.

  In the insulating film 5 made of amorphous ceramic, argon exists as a rare gas element that does not react with other elements, and by adding a large amount of rare gas elements into the film, the insulating film made of amorphous ceramic The deformation of 5 becomes easy and the effect of relieving internal stress is increased. Therefore, even if the insulating film 5 made of an amorphous ceramic having a thickness of 10 μm or more as in the present invention is formed on the conductive substrate 2 through the insulating layer 3 so as to cover the adsorption electrode 4, the insulating film 5 is formed. Generation of large stresses that cause peeling can be prevented.

  The argon amount in the insulating film 5 is controlled by increasing the gas pressure of argon at the time of film formation, and increasing the negative bias voltage applied to the conductive substrate 2 to be formed, thereby ionizing argon ionized in the plasma. A large amount of ions can be taken into the insulating film 5.

  The amount of argon in the insulating film 5 is preferably 1 to 10 atomic%. More preferably, it is 3-8 atomic%. When the content of the rare gas element is 1 atomic% or less, the insulating film 5 made of amorphous ceramic cannot be displaced sufficiently, so that the effect of relaxing the stress is reduced, and cracks are easily generated even with a thickness of about 10 μm. On the other hand, it is difficult to manufacture the rare gas element at 10 atomic% or more.

  Further, the same effect can be obtained by performing sputtering using another rare gas element instead of argon as the rare gas element. However, considering sputtering efficiency and gas cost, argon gas is preferable because it has high sputtering efficiency and is inexpensive.

  As a method for quantitative analysis of argon in the insulating film 5, an aluminum ceramic sintered body formed with an amorphous ceramic film with a thickness of 20 μm was prepared as a comparative sample, and the sample was analyzed by Rutherford backscattering method. The total atomic weight detected and the atomic weight of argon were measured, and the value obtained by dividing the atomic weight of argon by the total atomic weight was calculated as atomic%.

  Further, since the insulating film 5 made of amorphous ceramic contains a rare gas element as described above, the hardness is smaller than that of a ceramic sintered body having a similar composition. By adding a large amount of rare gas elements, the hardness can be reduced and the internal stress in the film can be reduced.

  The insulating film 5 made of amorphous ceramic is formed by a film forming process such as sputtering, and there are concave portions on the surface of the insulating film 5, but there are almost no voids inside the insulating film 5. Therefore, by removing the surface recesses by polishing the surface, the surface area exposed to the plasma can be minimized at any time, and since there is no grain boundary like a polycrystalline body, etching is uniform. It is difficult for threshing to occur. As a result, the plasma resistance of each step is superior to that of a conventionally used insulating film made of a ceramic multi-sintered body. In addition, although the surface roughness of the ceramic polycrystalline sintered body including the crystal grain boundary is up to about Ra0.02, the amorphous ceramic insulating film 5 can be reduced to about Ra0.0003 and is plasma resistant. From the viewpoint of

  Furthermore, the Vickers hardness of the insulating film 5 made of an amorphous ceramic containing a rare gas element is preferably 500 to 1000 HV0.1. If it exceeds 1000 HV0.1, the internal stress increases and the insulating film 5 may be peeled off. If the Vickers hardness of the insulating film 5 is less than 500 HV0.1, the internal stress of the insulating film 5 is small and the problem of peeling of the insulating film 5 hardly occurs. However, since the hardness is too small, the insulating film 5 is easily damaged. As a result, a withstand voltage drop occurs. This may cause damage to the insulating film 5 due to hard dust that has entered between the wafer W and the mounting surface 5a of the electrostatic chuck 1, and the withstand voltage of the damaged portion may be reduced. Therefore, the Vickers hardness of the insulating film 5 is preferably 500 to 1000 HV0.1, and more preferably 600 to 900 HV0.1.

  The insulating film 5 made of amorphous ceramic is preferably composed of aluminum oxide, yttrium oxide, yttrium aluminum oxide or rare earth oxide having excellent plasma resistance. In particular, yttrium oxide is excellent.

  In the conductive base 2 made of the metal and ceramic of the present invention, the thermal expansion coefficient of the conductive base 2 largely depends on the thermal expansion coefficient of the porous ceramic body forming the skeleton. As the ceramic, silicon carbide or aluminum nitride is used. Is preferred. In addition, since the thermal conductivity of the conductive substrate 2 largely depends on the thermal conductivity of the metal filled in the pores, the thermal expansion coefficient and the thermal conductivity of the conductive substrate 2 can be changed by changing the mixing ratio of the two. Can be adjusted appropriately. In particular, the metal is preferably aluminum or an aluminum alloy that has little influence on the wafer W.

  Therefore, the conductive substrate 2 is composed of any one metal component of aluminum or aluminum alloy and one ceramic component of silicon carbide or aluminum nitride, and the content of the ceramic component is 50 to 90% by mass. It is preferable.

  When the content of the ceramic component of the conductive substrate 2 is less than 50% by mass, the strength of the conductive substrate 2 is greatly reduced, and the thermal expansion coefficient of the conductive substrate 2 is higher than that of the porous ceramic body. Therefore, the insulating film 5 may be peeled off because the thermal expansion coefficient of the conductive substrate 2 becomes large and the difference in thermal expansion from the amorphous ceramic insulating film 5 becomes too large.

  On the contrary, if the content of the ceramic component of the conductive substrate 2 is more than 90% by mass, the open porosity of the ceramic becomes small and the aluminum alloy cannot be sufficiently filled, and heat conduction and electric conduction are extremely lowered. The function as a conductive substrate is not achieved. As the ceramic, a porous ceramic having low thermal expansion and high rigidity such as silicon nitride, silicon carbide, aluminum nitride, or alumina is used. In order to fill the pores with the aluminum alloy without gaps, it is desirable to use a porous ceramic body having a pore diameter of 10 to 100 μm.

  In addition, as a method of filling the pores of the porous ceramic body with metal, the molten metal may be injected into a press machine in which the porous ceramic body has been put in advance and heated, followed by pressure pressing.

Since the thermal expansion coefficient of the conductive substrate 2 can be changed to about 11 × 10 ^{−6 to} 5 × 10 ⁻⁶ / ° C. by setting the mass ratio of SiC to 50 to 90% by mass, the heat of the insulating film 5 It becomes possible to match the expansion coefficient and film formation stress.

  Further, since the corrosive gas in the etching process using the electrostatic chuck 1 of the present invention slightly penetrates the side surface of the electrostatic chuck 1 protected by a cover ring or the like not described or the exposed surface of the back surface of the plasma, It is preferable that the protective film 7 is present in order to improve the corrosion resistance against the above.

  It is preferable to form an alumina sprayed film or an anodic oxide film of aluminum on the side surface and the back surface of the conductive substrate 2 that is less eroded than the wafer mounting surface 5a to form the protective film 7. The alumina sprayed film is preferably formed to a thickness of 50 to 500 μm. The thickness of the aluminum anodized film is preferably 20 to 200 μm.

  In the case of forming an alumina sprayed film as the protective film 7, the material of the surface of the conductive substrate 2 is not limited. However, in the case of forming an aluminum anodic oxide film as the protective film 7, the surface of the conductive substrate 2 is made of an aluminum alloy. There must be. Even if the conductive substrate 2 obtained by impregnating the above-described porous ceramic body with an aluminum alloy is provided with an anodic oxide film, the anodic oxide film grows only on the surface of the aluminum part and the ceramic part is partially exposed. Since the plasma resistance is lowered and the insulation between the plasma atmosphere and the conductive substrate 2 is deteriorated, the conductive substrate 2 in which the aluminum alloy is formed on the surface of the conductive substrate 2 when impregnated with the aluminum alloy. Is preferably produced. And, by forming an anodic oxide film of aluminum, plasma resistance can be enhanced, and surface insulation can be provided by oxidizing aluminum on the surface.

  Although the protective film 7 covers the surface of the conductive substrate 2, it goes without saying that the exposed portion of the insulating layer 3 may be covered simultaneously.

  The insulating layer 3 is preferably made of polyimide instead of the glass or amorphous film. Since polyimide is a resin, it can be easily expanded and contracted, and there is no need to match the thermal expansion coefficient with that of the conductive substrate 2, so it is not necessary to limit the metal contained in the conductive substrate 2 to a metal with a low expansion coefficient, and it can be freely selected I can do it. Polyimide has a very high withstand voltage of 20 kV / mm or more, can be easily formed into a sheet, is mass-produced, and is commercially available. Further, since the thickness can be made uniform, heat from the mounting surface can be obtained. Since it can transmit uniformly to the electroconductive base | substrate 2, it is advantageous also from the point of the soaking | uniform-heating of the wafer W, and there exists a big merit from the said characteristic and cost side.

  The insulating layer 3 is made of polyimide, and the thickness of the insulating layer 3 is preferably 5 to 150 μm. If the thickness is less than 5 μm, dielectric breakdown may occur, and if it exceeds 150 μm, film formation becomes difficult as a sheet, resulting in poor mass production of the polyimide film. Considering the improvement of the withstand voltage and the thermal conductivity, the thickness of the insulating layer 3 made of polyimide is more preferably 10 to 75 μm.

  In addition, it is preferable to provide the protrusions 10 scattered on the surface of the insulating film 5 because the wafer W can come into contact with the small top surface of the protrusions 10 to reduce the generation of particles. In addition, a gap is formed between the wafer W and the insulating film 5 by interspersing the convex portions 10 on the insulating film 5, but a large adsorbing force can be maintained by adjusting the gap to be 5 μm or less. In addition, since the contact area between the wafer W and the electrostatic chuck 1 can be reduced, generation of particles can be suppressed.

  Furthermore, since the voltage applied to the convex portion 10 can be reduced by reducing the volume specific resistance of the convex portion 10, electrical damage to the convex portion 10 can be reduced, and the top surface of the convex portion 10 can be reduced. Thus, the adsorption force is reduced, and the generation of particles due to the friction between the top surface and the wafer W can be suppressed.

  The smaller the area for forming the convex portion 10 with respect to the area of the upper surface of the insulating film 5, the smaller the contact area. Further, it is preferable that the convex portions are small and interspersed, and the area of the top surface of the convex portion 10 is 20% or less, more preferably 10% or less of the area of the upper surface of the insulating film 5, and the scattered one by one. The top surfaces of the two protrusions 10 are preferably φ3 or less, preferably φ2 or less, and more preferably φ1 or less.

  If the height of the convex portion 10 is too large, the adsorptive power becomes small, and if the height is too small, there is a possibility that the surface of the insulating film 5 may come into contact with the surface and the generation of particles may increase. The height of the convex portion 10 is preferably 0.5 to 5 microns, more preferably 1 to 3 microns.

  Although the material of the convex part 10 has a big effect by TiN, TiC, SiC, DLC, etc., DLC with small abrasion is more preferable in the electrostatic chuck used in a vacuum.

  Next, a method for manufacturing the electrostatic chuck 1 of the present invention will be described.

  First, a plurality of ceramic green sheets made of alumina or aluminum nitride are stacked to form a laminated body, and an adsorption electrode 4 made of molybdenum paste or tungsten paste is printed on one main surface. On the other hand, a plurality of ceramic green sheets are separately stacked to produce a laminate. And after pressurizing and press-bonding, it is sintered together. By grinding the outer diameter of the sintered body and then grinding the thickness to 2 mm or less, a plate-like ceramic body in which the adsorption electrode 4 is embedded is obtained.

  A hole penetrating the adsorption electrode 4 is formed at a predetermined position of the plate-shaped ceramic body, and the power supply terminals 6a and 6b are brazed and joined. The electrostatic chuck 1 of the present invention can be obtained by bonding the conductive base 2 made of aluminum with a silicon adhesive or an epoxy adhesive.

  Next, a porous body of silicon carbide is impregnated with an aluminum alloy as the conductive substrate 2, and at the same time, an anodized film is formed on the conductive substrate 2 having a surface layer made of an aluminum alloy to form a plasma-resistant protective film 7 and oxidized. An electrostatic chuck 1 in which an amorphous ceramic insulating film 5 made of aluminum is formed by sputtering will be described.

To silicon carbide powder having an average particle size of about 60 μm, silicon oxide (SiO ₂ ) powder, a binder and a solvent were added and kneaded, and then granules were produced with a spray dryer. And after forming this disk-shaped molded object by the rubber press molding method, it has a porosity of 20% by firing at a temperature of about 1000 ° C. lower than the normal firing temperature in a vacuum atmosphere. A porous ceramic body made of silicon carbide is produced and processed into a desired shape.

  Then, this porous ceramic body is loaded into a die of a press machine, and after heating the die to 680 ° C., a molten aluminum alloy with a purity of 99% or more is filled into the die, and the punch is lowered at 98 MPa. Pressurized. Then, by cooling in this pressurized state, a porous ceramic body filled with an aluminum alloy as a metal in the pores is formed, and when a die having a size larger than the size of the porous ceramic body is used, the conductive body becomes conductive. An aluminum alloy layer is formed on the entire surface of the conductive substrate 2, and the conductive substrate 2 can be obtained by making it into a predetermined shape.

Then, the surface of the aluminum alloy layer on the surface of the conductive substrate 2 is subjected to an anodic oxide film treatment to obtain an aluminum anodic oxide film. In the anodic oxide coating treatment, γ-Al ₂ O ₃ is formed on the surface of an aluminum alloy by electrolyzing the conductive substrate 2 in an acid such as oxalic acid or sulfuric acid as an anode and carbon or the like as a cathode. Since this film is porous, the protective film 7 made of a dense boehmite (AlOOH) film can be obtained by immersing the film in boiling water or reacting with heated steam.

  In order to form the insulating layer 3 on the conductive substrate 2 on which the protective film 7 is formed, the protective film 7 on the surface on which the insulating film 5 is formed is removed by cutting, and then the surface of the conductive substrate 2 is mirror-finished. To finish as a film formation surface.

  In the case where an alumina sprayed film is formed as the protective film 7 on the conductive substrate 2, it is possible to increase adhesion by roughening the surface of the conductive substrate 2 by blasting or the like and then spraying alumina. . Further, when a Ni-based metal film is sprayed as a base treatment before the alumina spraying, the adhesion with the protective film 7 is large and preferable. The alumina sprayed film is formed by melting and irradiating alumina powder of about 40 to 50 μm with atmospheric plasma or reduced pressure plasma. In order to improve hermeticity, it is preferable to use reduced pressure plasma.

  Since there are open pores only in the sprayed film, the protective film 7 is formed by performing a sealing process by impregnating an organic silicon compound or an inorganic silicon compound and heating.

  The insulating layer 3 formed on the finished surface of the conductive substrate 2 may be coated with an amorphous glass layer or formed by sputtering the same amorphous ceramic film as the insulating film 5 in plasma. 3 is also acceptable.

  When polyimide is used as the insulating layer 3, a polyimide film having a silicone, acrylic or epoxy adhesive applied to the back surface is placed on the conductive substrate 2 and degassed and heated by a vacuum press. The insulating layer 3 made of polyimide can be formed on the conductive substrate 2 by pressing.

  Alternatively, the polyimide film may be disposed on the conductive substrate 2, heated to 350 ° C. or higher and pressurized in a vacuum press machine to be fused to the conductive substrate 2.

  A thin polyimide film can be formed on the conductive substrate 2 by forming a film of the polyimide solution on the conductive substrate 2 using a spin coater, a roll coater, or the like, and heating in nitrogen.

  Then, the adsorption electrode 4 can be formed by forming 0.1 to 30 μm of titanium, copper, gold, nickel, or aluminum film on the insulating layer 3. Then, an insulating film 5 is formed so as to cover the adsorption electrode 4.

  Also, a polyimide film with a copper foil affixed thereto is commercially available, and the copper foil is etched to form an electrode pattern, and the surface opposite to the electrode pattern is affixed to the conductive substrate 2, and the adsorption electrode 4 is also used. It can also be formed simultaneously.

  The insulating film 5 made of amorphous ceramic is produced by sputtering. A target having a composition desired to be formed as the insulating film 5 is set in a parallel plate type sputtering apparatus. Here, the aluminum oxide sintered body is used as a target, and the conductive substrate 2 is set in a copper holder so as to face the target. By applying and bonding a liquid alloy composed of In and Ga on the back surface of the conductive substrate 2 and the holder surface, heat transfer between the conductive substrate 2 and the holder is increased, and the cooling efficiency of the conductive substrate 2 can be increased. As a result, the insulating film 5 made of a high-quality amorphous ceramic can be formed.

  Thus, after setting the electroconductive base | substrate 2 in the chamber of a sputter | spatter and making a vacuum degree 0.001Pa, argon gas is flowed 25-75 sccm.

  Then, plasma is generated by applying an RF voltage between the target and the holder. Then, pre-sputtering of the target and etching on the ceramic substrate 2 side are performed for several minutes to clean the target and the conductive substrate 2.

The insulating film 5 made of an amorphous ceramic made of aluminum oxide is sputtered with the RF power set to 3 to 9 W / cm ² . In addition, a bias of about −100 to −200 V is applied to the conductive substrate 2 side to attract molecules ionized from the target and ionized argon ions. However, if the conductive substrate 2 is insulated, the surface of the conductive substrate 2 is charged by the ionized argon ions, and the next argon ions are difficult to enter. Argon ions entering the film release electric charge, return to the argon state, and remain in the film. In order to take in a large amount of argon into the film, the charge is released from the power supply port of the conductive substrate 2 through the InGa layer and the path of the holder at the time of film formation, so that argon is always easily taken into the insulating film 5 made of amorphous ceramic. It is necessary.

  Further, if the conductive substrate 2 is poorly cooled, the amorphous ceramic insulating film 5 is partially crystallized from amorphous, and the withstand voltage is partially deteriorated or the plasma resistance is deteriorated. The conductive substrate 2 is preferably cooled by flowing cooling water through the cooling plate of the apparatus to sufficiently cool the inside of the substrate holder and maintain the temperature of the conductive substrate 2 at several tens of degrees.

  The insulating film 5 was formed at a rate of 3 μm / hour for 17 hours, and the insulating film 5 made of amorphous ceramic having a thickness of about 50 μm was produced.

  Thereafter, the mounting surface 5a is formed by preparing the surface of the amorphous ceramic insulating film 5 by polishing or the like, and the electrostatic chuck 1 is completed. The mounting surface 5a can be provided with a recess by blasting or etching. Gas is filled between the recess and the wafer W to increase the thermal conductivity between the wafer W and the mounting surface 5a, and the mounting surface 5a made of amorphous ceramic has a reduced surface roughness. Therefore, it may be adsorbed by surface contact with the surface of the wafer W, and if a recess of 50% or more with respect to the area of the mounting surface 5a is provided, deterioration of the separation characteristics of the wafer W due to surface adsorption can be prevented.

  A SiC porous body having a diameter of 298 mm and a thickness of 28 mm is impregnated with an aluminum alloy, and an aluminum alloy layer having a thickness of 1 mm is provided on the side surface and the upper and lower surfaces. A conductive substrate having a thickness of 30 mm was obtained. And the insulating layer which consists of an amorphous ceramic was formed into a film with the thickness of 5-50 micrometers on the upper surface. Thereafter, an adsorption electrode having a thickness of 1 μm is formed thereon by gold plating, a hole penetrating the conductive substrate is drilled, a power supply terminal is attached through an insulating tube, and an alumina film as an amorphous ceramic is further formed thereon. A film of 5 to 50 μm was formed. Thereafter, the film-forming surface was polished and used as a mounting surface. 1-5 were produced.

  Sample No. After coating the upper surface of the same conductive substrate as used in 1 and forming an adsorption electrode by gold plating, sample No. 6 having an alumina sprayed film on the entire surface and an anodic oxide film were formed. Sample No. 1 having a 10 μm amorphous aluminum oxide film formed thereon was formed. 7 was produced.

  Further, 0.5% by mass of calcium oxide and magnesium oxide in terms of weight was added to the alumina powder and mixed for 48 hours by a ball mill. The resulting alumina slurry was passed through a 325 mesh to remove balls and ball mill wall debris, and then dried at 120 ° C. for 24 hours in a dryer. The resulting alumina powder was mixed with an acrylic binder and a solvent to prepare an alumina slurry. A green tape was produced from this alumina slurry by the doctor blade method.

  Then, a plurality of the green tapes were stacked to produce a laminated body, and an adsorption electrode made of a tungsten carbide paste was printed on one main surface. On the other hand, a plurality of ceramic green sheets were separately laminated to produce a laminate, which was pressed and pressed to produce a laminate.

  Further, firing was performed at 1600 ° C. for 2 hours in a firing furnace made of a W heater and a W heat insulating material in a nitrogen atmosphere to obtain an alumina plate-shaped ceramic body having an outer diameter of 305 mm and a thickness of 2 mm. Then, the outer diameter was 300 mm and the thickness was ground to 0.8 mm, the hole penetrating the adsorption electrode was processed, and the power supply terminal was brazed.

  On the other hand, the plate-shaped ceramic body was joined to a conductive substrate made of an aluminum alloy having a diameter of 300 mm and a thickness of 30 mm with a silicon adhesive, and electrostatic chuck sample No. 1 was obtained. 8 was obtained.

Further, 15% by weight of CeO ₂ was added as a sintering aid to AlN powder having a purity of 99% and an average particle size of 1.2 μm. Further, an organic binder and a solvent were added to prepare mud, and a plurality of aluminum nitride green sheets having a thickness of about 0.5 mm were manufactured by a doctor blade method. Of these, one aluminum nitride green sheet was screen-printed with a conductive paste in the shape of an adsorption electrode.

  As the conductive paste that becomes the electrode for electrostatic adsorption, a conductive paste in which the viscosity was adjusted by mixing WC powder and AlN powder was used.

  Then, the aluminum nitride green sheets were stacked in a predetermined order and thermocompression bonded at 50 ° C. with a pressure of 4.9 kPa to form an aluminum nitride green sheet laminate, which was cut into a disk shape.

  Next, the aluminum nitride green sheet laminate is vacuum degreased and then fired at a temperature of 1850 ° C. in a nitrogen atmosphere to obtain a plate-like ceramic body made of an aluminum nitride-based sintered body with an electrostatic adsorption electrode embedded therein. Produced.

  Thereafter, the obtained plate-shaped ceramic body is ground, and the outer shape is 300 mm, the plate thickness is 1000 μm to 4000 μm, the distance from the mounting surface to the adsorption electrode and the back surface of the plate-shaped ceramic body from the adsorption electrode. After grinding so that the distance is equal, lapping is performed on the mounting surface 3 described above, and the surface roughness is finished to 0.2 μm in arithmetic mean roughness (Ra) to form a mounting surface. Holes communicating with the electrostatic chucking electrodes were drilled on the surface opposite to the placement surface, and a feeding terminal was inserted into each hole and brazed to obtain a plate-like ceramic body in which the chucking electrodes were embedded.

  And the said plate-shaped ceramic body is sample No.2. No. 1 is bonded to a conductive substrate made of the same aluminum alloy and SiC with a silicon adhesive as electrostatic chuck sample No. 9, 10, and 11.

  And the temperature change of a mounting surface, the dielectric breakdown of an insulating film, a crack, peeling, and plasma resistance were evaluated.

  Each sample was provided with a hole for inserting a thermocouple directly under the center of the mounting surface at the center, and the temperature change of the mounting surface was measured with the thermocouple. In addition, a water cooling passage was provided in the conductive substrate, and a constant amount of temperature-controlled cooling water was supplied.

  The dielectric breakdown of the insulating film was evaluated by applying a 3 kV voltage to the adsorption electrode to evaluate the presence or absence of dielectric breakdown.

The evaluation of plasma resistance, covering the sides with a cover ring on the side surface of the electrostatic chuck, in a state where not place the wafer W on the wafer mounting surface, 4 Pa while flowing 60sccm the Cl ₂ as halogen gas As a degree of vacuum, plasma is generated between the counter electrode and the mounting surface while supplying a high-frequency power of 2 kW between the counter electrode disposed above the mounting surface and the conductive substrate 2, and plasma is applied to the mounting surface for 100 hours. Exposed. Thereafter, the state of the insulating film is observed, and the insulating film is corroded and the conductive substrate is not exposed, the surface of the mounting surface is not uneven, the plate-like ceramic body and the conductive substrate The adhesion state was observed. Further, the difference between the temperature before the plasma generation and the temperature of the mounting surface after 1 hour after the generation was evaluated as the temperature change of the mounting surface.

  The electrostatic attraction force is measured at room temperature and in a vacuum, a 1-inch square Si wafer is placed on the mounting surface, 500 V is applied to the wafer W and the conductive substrate 2, and the Si wafer is pulled up after 1 minute. The force required for the pulling was measured with a load cell, and the value was divided by the area of the mounting surface to obtain an electrostatic adsorption force per unit area. The residual adsorption force is measured in a vacuum, a 1-inch square Si wafer is placed on the mounting surface, 500 V is applied for 2 minutes, the voltage is turned off, and the Si wafer is pulled up after 3 seconds. The required force was measured with a load cell, and the value was divided by the area of 1 inch square of the mounting surface to obtain the residual adsorption force per unit area.

The results are shown in Table 1.

  Sample No. 2 in which the total thickness of the insulating layer and insulating film of the present invention is 20 to 2000 μm. 2 to 10 show that the temperature change of the mounting surface is as small as 5 ° C. or less, and the dielectric breakdown, cracks and peeling of the insulating film are not seen and show excellent characteristics.

  On the other hand, Sample No. 1 in which the insulating film made of amorphous ceramic had a small thickness did not show cracks or peeling, but could not be used in a short time because it was corroded by plasma and the conductive substrate was exposed. In Sample No. 11, the total thickness of the insulating film and the insulating layer is as large as 4000 μm, the mounting surface is heated by plasma, the temperature of the mounting surface rises by 50 ° C., and the wafer W is processed at a predetermined temperature. I found it impossible.

  Sample No. Nos. 2-5 show that since the insulating film is made of amorphous ceramic, there is no change in temperature of the mounting surface, there is no dielectric breakdown or cracking of the insulating film, plasma resistance is good, and excellent characteristics are shown. It was.

Furthermore, sample no. Nos. 2 to 4 showed that the thickness of the insulating film was 10 to 100 μm, the adsorbing force was as large as 2500 N / m ² or more, and the residual adsorbing force was 10 Pa or less, showing further excellent characteristics.

Further, sample No. 1 provided with an insulating film made of amorphous alumina on an anodic oxide film of aluminum. 11 is the suction force is preferably as large as 3500 N / m ^2, slightly larger, the volume resistivity of the residual suction force is slightly greater for the anodic oxide film and the amorphous aluminum oxide film residual attracting force between 300N / m ² Is considered to be due to the difference.

  Next, the conductive substrate 2 is made of the composite material having a diameter of 300 mm used in Example 1, amorphous aluminum oxide is used as the insulating film 5, and various film forming conditions are changed to form the amorphous ceramic insulating film 5. Films with different amounts of argon were prepared, and the presence or absence of peeling or cracking was evaluated.

The peeling and cracking were evaluated before and after repeating the plasma cycle of generating plasma on the upper surface of the electrostatic chuck for 10 minutes and then stopping for 10 minutes in the same manner as in Example 1.

  Sample No. with small argon amount of 0.5 atomic% In No. 21, a crack occurred in the insulating film.

  However, sample No. 1 containing 1 to 10 atomic% of argon as the rare gas element of the present invention. In Nos. 22 to 25, cracks were not generated in the insulating film, and since dielectric breakdown was not caused, it was found that the rare gas elements are preferably 1 to 10 atomic%.

  Next, the conductive substrate 2 uses 300 mm in diameter and 30 mm in thickness used in Example 1, uses amorphous aluminum oxide as the insulating film 5, and changes the film formation conditions to change the Vickers hardness of the insulating film 5. A film was prepared, and the presence or absence of peeling or cracking was confirmed.

  What provided the insulating film 5 which consists of the amorphous ceramic of 30 micrometer aluminum oxide produced on various film-forming conditions on the electroconductive base | substrate 2 was evaluated.

The Vickers hardness was measured from the size of the indentation corresponding to the hardness symbol HV0.1 of JIS R1610 with a load of 0.98 N applied for 15 seconds.

  Sample No. Vickers hardness as small as 400HV0.1 No cracks occurred in 31 but dielectric breakdown occurred. This is probably because the hardness was too small, so that the film was scratched and, therefore, dielectric breakdown occurred. Further, a sample No. having a large Vickers hardness of 1200 HV0.1. In 35, cracks occurred in the insulating film. This is probably because the film could not relax the internal stress and cracks occurred.

  Therefore, it was found that the Vickers hardness is preferably 500 to 1000 HV0.1 as in sample Nos. 32 to 34.

  Sample No. in which the material of the insulating film made of amorphous ceramic was changed to aluminum oxide, yttrium oxide, yttrium aluminum oxide, cerium oxide. As a comparative example, Sample Nos. 41 to 44, each of which has an insulating film made of polycrystalline alumina. 45 was exposed to plasma and the etching rate of the insulating film was compared.

In the evaluation method, a cover ring was provided on the outer peripheral surface and side surface of the electrostatic chuck to cover a portion where the insulating film was not attached, and the insulating film surface was irradiated with plasma. The plasma condition is that the vacuum is 4 Pa while flowing Cl ₂ as halogen gas at 60 sccm, and the plasma is applied to the counter electrode while supplying a high-frequency power of 2 kW between the counter electrode disposed above the mounting surface and the conductive substrate. It was generated between the mounting surfaces and exposed to plasma for 2 hours. And the etching rate was computed from the abrasion thickness by the etching of an insulating film. The value obtained by dividing the wear thickness of each film by the wear thickness of sintered alumina was taken as the etching rate. The results are shown in Table 4.

  Sample No. made of polycrystalline alumina For the etching rate of 45, an aluminum oxide film No. 1 made of amorphous ceramic is used. 51 is as small as 0.7, and the etching rates of the insulating film 5 made of amorphous ceramic such as yttrium oxide, yttrium aluminum oxide, and cerium oxide are 0.2, 0.3, and 0.3, respectively, which are much smaller. It was found that the plasma resistance was excellent.

  Using an SiC alloy having a diameter of 298 mm and a thickness of 28 mm that was changed to 50 to 90% by mass (the rest being an aluminum alloy), an aluminum alloy layer having a thickness of 1 mm was provided on the side surface and the upper and lower surfaces. An aluminum oxide film made of an amorphous ceramic was formed on the upper surface of the conductive substrate 2, and a temperature cycle test of -20 ° C to 200 ° C was conducted, but no cracks were found in the amorphous aluminum oxide film. It was.

  A SiC porous body having a diameter of 298 mm, a thickness of 28 mm of SiC of 80% by mass and an aluminum alloy of 20% by mass is impregnated with an aluminum alloy, and an aluminum alloy layer having a thickness of 1 mm is provided on the side and upper and lower surfaces. An electrostatic chuck 1 produced by forming amorphous aluminum oxide on the upper surface of the conductive substrate 2 and forming an anodic oxide film of aluminum as a plasma-resistant protective film on the other surface and a sprayed film of alumina— Although the test was conducted at a temperature cycle of 20 ° C. to 200 ° C., no crack was found in the protective film.

  A conductive substrate made of an aluminum alloy and having a diameter of 300 mm and a thickness of 30 mm was produced. Then, an adsorption electrode is formed by etching a polyimide copper foil with a 2 micron copper foil, and the opposite surface of the copper foil is attached to a conductive substrate made of an aluminum alloy. It was formed with a thickness of ˜150 μm. Thereafter, a hole penetrating the conductive substrate was drilled and a power supply terminal was attached via an insulating tube, and then an alumina film of 50 μm was formed thereon as an amorphous ceramic. Thereafter, the film-forming surface was polished and used as a mounting surface. 51-56 were produced.

  Each sample to be evaluated was provided with a hole for inserting a thermocouple directly under the center of the mounting surface at the center, and the temperature change of the mounting surface was measured with the thermocouple. In addition, a water cooling passage was provided in the conductive substrate, and a constant amount of temperature-controlled cooling water was supplied.

  And it evaluated similarly to Example 1. FIG.

The results are shown in Table 5.

  Sample No. in which the insulating layer 3 made of polyimide of the present invention has a thickness of 5 to 150 μm. Nos. 52 to 56 show that the temperature change of the mounting surface is further as small as 1 ° C. or less, and the dielectric breakdown, cracks and peeling of the insulating film are not seen and show excellent characteristics.

  On the other hand, in sample No. 51 having a thickness of the insulating layer smaller than 5 μm, the polyimide insulating layer breaks down between the conductive substrate and the adsorption electrode.

It is sectional drawing of the electrostatic chuck of this invention. It is sectional drawing which shows other embodiment of this invention. It is sectional drawing which shows other embodiment of this invention. It is sectional drawing which shows other embodiment of this invention. It is sectional drawing of the conventional electrostatic chuck. It is sectional drawing of the conventional electrostatic chuck. It is sectional drawing of the conventional electrostatic chuck.

Explanation of symbols

1, 21, 51: Electrostatic chuck
5, 52: Insulating films 5a, 22a, 52a: Wafer mounting surface 2: Conductive substrate 7: Protective film 23: Composite material 24: Aluminum alloy substrate 25: Alumina sprayed film 26: Anodized film 27: Feed port

Claims (13)

An insulating layer is provided on one main surface of the conductive substrate, an adsorption electrode is provided on the upper surface thereof, and an insulating film is provided so as to cover the adsorption electrode. The upper surface serves as a mounting surface on which a wafer is placed, and is insulated from the insulating layer. An electrostatic chuck having a total thickness of 20 to 2000 μm with the film. The electrostatic chuck according to claim 1, wherein the insulating film is formed so as to cover the insulating layer. The electrostatic chuck according to claim 1, wherein the insulating layer is made of an amorphous ceramic. The electrostatic chuck according to claim 1, wherein the insulating film is made of a uniform amorphous ceramic made of an oxide and has a thickness of 10 to 100 μm. 5. The electrostatic chuck according to claim 1, wherein the insulating film contains 1 to 10 atomic% of a rare gas element and has a Vickers hardness of 500 to 1000 HV0.1. 6. The electrostatic chuck according to claim 1, wherein the insulating film is mainly composed of any one of aluminum oxide, rare earth oxide, and nitride. The conductive substrate is composed of any one metal component of aluminum or aluminum alloy and one ceramic component of silicon carbide or aluminum nitride, and the content of the ceramic component is 50 to 90% by mass. The electrostatic chuck according to claim 1. The electrostatic chuck according to claim 1, wherein a protective film made of an alumina film is formed on the surface of the conductive substrate other than the surface on which the insulating film is formed. The electrostatic chuck according to claim 1, wherein the insulating layer is made of polyimide. The electrostatic chuck according to claim 9, wherein the insulating layer has a thickness of 5 to 150 μm. The electrostatic chuck according to claim 1, comprising convex portions scattered on the surface of the insulating film. The electrostatic chuck according to claim 11, wherein a volume resistivity of the convex portion is smaller than a volume resistivity of the insulating film. The electrostatic chuck according to claim 11, wherein a height of the convex portion is 0.5 to 5 μm.

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