JP4565136B2 - Electrostatic chuck - Google Patents

Description

  The present invention relates to an electrostatic chuck that attracts an object to be processed such as a semiconductor wafer or a glass substrate, and a method for manufacturing the same.

  An electrostatic chuck is widely used as a member that strongly fixes a semiconductor wafer while maintaining the flatness of the semiconductor wafer, for example, in a semiconductor manufacturing apparatus that processes the semiconductor wafer by a method such as dry etching, sputtering, or CVD. It is composed of a dielectric layer to be held and an electrode for generating an electrostatic force for fixing and holding, and is used by being bonded and fixed on a cooling plate called a jacket having a cooling function. Ceramics and polymer materials are used for the dielectric layer.

 When using ceramics such as aluminum oxide as a dielectric layer, conventional electrostatic chucks have a binary or higher composition with titanium oxide added so that optimum adsorption force can be achieved in the operating temperature environment. In addition to the Coulomb force, which is a pure electrostatic force, it uses the Johnsen-Rahbek force generated in the state where a very small current flows to obtain a strong adsorption force. Alternatively, an electrostatic chuck using polyimide or the like as a dielectric layer of a polymer material is also used.

 As a conventional method for producing an electrostatic chuck, for example, as disclosed in Japanese Patent Application Laid-Open No. Sho 62-264638, a conductor layer to be an electrode is formed on a ceramic green sheet, and the ceramic green sheet is laminated thereon and fired. A typical method is grinding and polishing from the surface.

 As another conventional manufacturing method, for example, as disclosed in JP-A-9-69554, a metal substrate is blasted to form irregularities on the surface, and then a metal sprayed coating is formed as an undercoat layer, and an oxide is formed thereon. Aluminum / titanium oxide binary ceramic sprayed material is coated by plasma spraying to form a topcoat layer, the surface is polished, and a silicon compound is applied to seal the holes generated on the surface. There is a technique to do. This method is excellent in productivity and is expected to be improved in terms of stability of electrical resistivity and adhesion as compared with the conventional thermal spraying method.

 Although there is no description about application to an electrostatic chuck, as a new film forming method for forming a ceramic layer on a substrate surface, a gas deposition method (Keishu Seiichiro: Metal January 1989 issue) or electrostatic The fine particle coating method (Ikawa et al .: Preprint of the academic meeting of the Fall Meeting of the Japan Society for Precision Machinery in 1977) is known. In the former, ultrafine particles such as metals and ceramics are aerosolized by gas agitation and accelerated through a minute nozzle. When they collide with the substrate, part of the kinetic energy is converted into thermal energy, and between the particles or between the particles and the substrate. The basic principle is to sinter. The latter is charged with fine particles and accelerated using an electric field gradient. After that, as with the gas deposition method, sintering is performed using the thermal energy generated during the collision. Is the basic principle.

 Further, as prior arts that improve the gas deposition method or the electrostatic fine particle coating method described above, JP-A-8-81774, JP-A-10-202171, JP-A-11-21677, or JP-A-2000-212760. What is disclosed in the Gazette is known. These prior arts also do not describe application to an electrostatic chuck.

 In the technique disclosed in Japanese Patent Laid-Open No. 8-81774, two types of metals or organic substances having different melting points are heated and evaporated by resistance wire heating, electron beam heating, high frequency induction heating, sputtering, arc plasma, etc. By using a nozzle for each metal having a different melting point, the ultrafine particles are sprayed onto the substrate based on the cross-sectional CAD data of a three-dimensional shape. By repeating, a three-dimensional solid object composed of two types of metals having different melting points is formed, and then the low-melting point metal part is melted by heating the three-dimensional solid object at an intermediate temperature between the melting points of the two types of metals. It is removed to leave only the refractory metal part.

 The technique disclosed in Japanese Patent Application Laid-Open No. 10-202171 is for spraying ultrafine particles obtained by heating and evaporation using the resistance wire heating, electron beam heating, high frequency induction heating, sputtering, arc plasma, or the like toward the substrate. In this case, a three-dimensional object having no shoulder is obtained by performing through the opening of the mask.

 The technique disclosed in Japanese Patent Application Laid-Open No. 11-21677 prevents the ultrafine particles from aggregating into large particles when transporting the aerosol containing the ultrafine particles or when the metal or ceramic is heated and evaporated. In order to do so, a classifier is arranged in an intermediate path.

The technique disclosed in Japanese Patent Application Laid-Open No. 2000-212760 is an ultrafine particle having a particle diameter of 10 nm to 5 μm (unlike that obtained by heating and evaporation unlike the prior art), an ion beam, an atomic beam, a molecular beam, or By irradiating with low temperature plasma etc., the ultrafine particles are activated without melting them, and sprayed on the substrate at a speed of 3 m / sec to 300 m / sec in this state, thereby promoting the bonding between the ultrafine particles and the dielectric. A layer is formed.

Among the conventional methods described above, the green sheet method inevitably causes warping after firing because the laminate of plastic deformable bodies is fired. After firing, surface grinding is performed from the surface to process the thinnest dielectric layer as thin as possible, but the internal electrode is warped, so there is a limit to the grinding of the dielectric layer from the electrode to the surface The distance is generally limited to a few hundred μm. In addition, the distance from the warped internal electrode to the surface varies within an individual, and individual differences also occur. This causes an individual difference in the adsorption performance of the electrostatic chuck. In addition, since the dielectric layer is thick, ceramics with relatively high electrical resistivity, such as aluminum oxide, and excellent mechanical properties, in order to generate sufficient adsorption power, have relatively low electrical resistivity, such as titanium oxide. The material was mixed to devise the Johnsen-Rahbek effect, but there was a problem that metal components such as titanium adhered due to frictional wear with the wafer when using an electrostatic chuck and contaminated the wafer. .

 Furthermore, an electrostatic chuck manufactured by the green sheet method is used by thermally fusing a metal cooling plate with a bonding material such as indium, for example, but the thickness of the ceramic dielectric having inferior thermal conductivity, ie, electrostatic Since the thickness of the chuck itself is several millimeters, the cooling efficiency is poor, and therefore it is necessary to suppress the amount of heat introduced into the wafer in the dry etching process, or it may cause a non-uniform temperature distribution within the wafer surface. There was a problem.

In addition, in the green sheet method, it is difficult to form a polycrystalline body composed of nanometer-level crystal grains, and since firing is performed using a sintering aid, a specific element segregates at the interface between the particles, It becomes a cause that obstructs achievement of a desired characteristic.

 On the other hand, in PVD, CVD, etc., because of the characteristics of the method of forming a dielectric layer by depositing atoms, it grows preferentially from a crystal plane with a low crystal growth energy, so that it has orientation or is columnar from the substrate. It is difficult to form a granular polycrystal having a characteristic structure such as formation of crystals and disordered crystal orientation.

 When the thermal spraying method is used, the dielectric layer is generally porous, and the presence of pores in the film reduces the dielectric breakdown voltage of the film or is restricted by the ceramic spray material used. It is necessary to form the coating thickness with a relatively thick film of 50 to 500 μm. Further, when the surface is polished, the surface becomes porous, so that the specific surface area becomes large, and depending on the use environment, the deterioration due to corrosion of the dielectric layer is caused. For this reason, it is necessary to apply a silicon compound to the surface again.

 In order to generate sufficient adsorption power, for example, when aluminum oxide is used as the main raw material, it is necessary to add titanium oxide to this to lower the electrical resistivity. Titanium oxide is still a problem as a contamination source for wafers. It becomes. In particular, when the surface is porous, the wear resistance is inferior to that of the dense material, which causes the contamination of the wafer. From the viewpoint of the contamination source, the anode and cathode used for the thermal spray nozzle are slightly eluted and mixed into the dielectric layer. This also affects the electrical resistivity and the withstand voltage value.

 In the case where a polymer material such as polyimide is used for the dielectric layer, there is a problem that the wear resistance is inferior, which promotes contamination in the wafer and the manufacturing apparatus and increases the frequency of replacement of the electrostatic chuck. In addition, it is inferior in heat resistance because of organic materials.

 In the production of a ceramic film by the sol-gel method, a technique has been developed that can produce a film having a relatively small crystallite at a low temperature. However, generally, the film thickness achieved in one film formation process is several nanometers to several hundreds of nanometers, and this process needs to be repeated when forming a thick film. At this time, in order to substantially strengthen the underlayer film, it is necessary to perform a heat treatment, and grain growth of the underlayer occurs. There is a problem that the density does not increase in the case of film formation at a low temperature that does not cause grain growth. Moreover, the problem that a crack occurs in the film after many film forming steps has not been solved. In addition, there are many wet methods for producing a fine-structure ceramic film such as the sol-gel method or the precipitation method in solution, and other solutes or solvents in the solution are mixed in the film, resulting in deterioration of film characteristics or compositional deviation. There is.

On the other hand, in the methods disclosed in JP-A-8-81774, JP-A-10-202171, and JP-A-11-21777, heating means for obtaining ultrafine particles (resistance wire heating, electron beam) Heating, high frequency induction heating, sputtering, arc plasma, etc.) are required. The basic principle is to convert kinetic energy into thermal energy and sinter in the event of a collision, and when this is applied to the manufacture of an electrostatic chuck, the particle size of the dielectric layer formed on the substrate is Due to grain growth, it becomes larger than the ultrafine particles of the raw material.

 On the other hand, the present inventors have continued to make additional tests on the technique disclosed in Japanese Patent Application Laid-Open No. 2000-2127760. As a result, it was found that metals (extensible materials) and brittle materials such as ceramics and metalloids behave differently. That is, in the case of a brittle material, a dielectric layer could be formed without irradiation with an ion beam, an atomic beam, a molecular beam, a low temperature plasma, or the like, that is, without using a special activation means. However, the peel strength of the dielectric layer is insufficient or only partially when the particle size of the fine particles, which are the conditions described in the publication, is 10 nm to 5 μm and the collision speed is 3 m / sec to 300 m / sec. New problems such as easy peeling and non-uniform density occurred.

 The present invention is a proposal of an electrostatic chuck and a manufacturing method thereof in view of these problems, and the thickness of the ceramic dielectric portion, which is largely related to the electrostatic attraction force, is relatively thin and dense. Therefore, an object of the present invention is to provide an electrostatic chuck excellent in various characteristics required for an electrostatic chuck such as thermal conductivity, wear resistance, corrosion resistance, and contamination because it does not contain heavy metals.

The present invention has been made based on the following findings. Ceramics are in an atomic bond state having a strong covalent bond or ionic bond with few free electrons. Therefore, the hardness is high, but it is vulnerable to impact. Semimetals such as silicon and germanium are also brittle materials that do not have spreadability. Therefore, when a mechanical impact force is applied to these brittle materials, for example, the crystal lattice shifts along the wall open surface such as the interface between crystallites, or is crushed. When these phenomena occur, the atoms that were originally present inside the slipping surface or fracture surface and were bonded to another atom are exposed, that is, a new surface is formed. The part of the atomic layer on this new surface is exposed to an unstable surface state by an external force from an originally stable atomic bond state. That is, the surface energy is high. The active surface joins the adjacent brittle material surface, the newly formed brittle material surface, or the substrate surface, and shifts to a stable state. The addition of a continuous mechanical impact force from the outside causes this phenomenon to occur continuously, and the joining progresses and the deposits formed thereby are densified by repeated deformation and crushing of fine particles. In this way, a deposit of brittle material is formed.

 The microscopic structure of the dielectric layer of the electrostatic chuck according to the present invention manufactured based on the above knowledge is clearly different from that obtained by the conventional manufacturing method. That is, the dielectric layer of the electrostatic chuck according to the present invention is bonded directly to a substrate as an electrode or a substrate on which a plurality of electrodes are arranged, and is polycrystalline, and a glassy grain boundary is formed at the interface between the crystals. The dielectric layer substantially does not exist, and a part of the dielectric layer is an anchor portion that bites into the substrate surface, and the dielectric layer has an average crystallite diameter of 500 nm or less and a density of 70%. That's it.

Here, the interpretation of the words that are important for understanding the present invention will be described below.
(Polycrystalline) In this case, it refers to a structure in which crystallites are joined and accumulated. The crystallite is essentially one crystal, and its diameter is usually 5 nm or more. In the manufacturing method of the present application, the average diameter is generally very fine at the nanometer level. However, rare cases occur in which the fine particles are taken into the dielectric layer without being crushed, but are substantially polycrystalline.
(Crystal orientation) In this case, it refers to the orientation of crystal axes in a dielectric layer that is polycrystalline. Whether or not there is orientation is generally X-ray powder diffraction, etc. JCPDS (ASTM) data, which is standard data by, is determined as an index. In the present case, in the view as shown in Example 4 described later, a case where the deviation of the main peak is within 30% is referred to as having substantially no orientation.
(Interface) In this case, it refers to the region that forms the boundary between crystallites.
(Grain boundary layer) A layer with a certain thickness (usually several nanometers to several micrometers) located at the grain boundary in the interface or sintered body, and usually takes an amorphous structure different from the crystal structure in the crystal grain, and in some cases Is accompanied by segregation of impurities.
(Anchor part) In this case, it refers to the irregularities formed at the interface between the substrate and the dielectric layer. In particular, the surface accuracy of the original substrate is not determined when the dielectric layer is formed, rather than having irregularities formed on the substrate in advance. It refers to the unevenness formed by changing.
(Average crystallite diameter) This is the crystallite size calculated by Scherrer's method in the X-ray diffraction method. In this case, it was measured and calculated using MXP-18 manufactured by Mac Science.
(Internal strain) Lattice strain contained in fine particles, which is a value calculated by using the Hall method in X-ray diffraction measurement, and the deviation is expressed in percentage with reference to a standard material in which fine particles are sufficiently annealed.
(Re-aggregation) This refers to the state in which fine fragments crushed and dropped from the surface of the primary particles of the fine particles during pulverization of the fine particles adhere to and bind to the surface of the primary particles (not necessarily the same) to form a surface layer.
(Velocity of the brittle material fine particles when colliding with the substrate) With respect to the velocity of the brittle material fine particles, it means the average velocity measured according to the method described in Example 3.

 In a dielectric layer formed by conventional sintering, crystals are accompanied by grain growth due to heat, and in particular when a sintering aid is used, a glass layer is formed as a grain boundary layer. On the other hand, since the dielectric layer of the electrostatic chuck according to the present invention involves deformation or crushing of the raw material fine particles, the constituent particles of the dielectric layer are smaller than the raw material fine particles. For example, the average crystallite size of the dielectric layer formed by setting the average particle size of the fine particles measured by the laser diffraction method or the laser scattering method to 0.1 to 5 μm is often 100 nm or less, It has a polycrystalline body composed of such fine crystallites as its structure. As a result, the average crystallite diameter is 500 nm or less and the density is 70% or more, or the average crystallite diameter is 100 nm or less and the density is 95% or more, or the average crystallite diameter is 50 nm or less and the density is 99% or more. It can be a dense dielectric layer. Here, the density (%) is obtained from the formula of bulk specific gravity / true specific gravity × 100 (%) using the true specific gravity based on literature values and theoretical calculation values and the bulk specific gravity obtained from the weight and volume value of the dielectric layer. Calculated.

 The electrostatic chuck has a function of chucking a semiconductor wafer such as silicon several tens of thousands of times, and is exposed to a heating and cooling cycle of tens of thousands of times by a heating operation such as etching. At this time, frictional wear occurs between the wafer and the electrostatic chuck due to a difference in the coefficient of thermal expansion, and contamination due to adhesion of wear powder to the wafer is a problem. The dielectric layer of the electrostatic chuck of the present invention Since it is a fine polycrystal, it has excellent wear resistance and can reduce contamination.

 Further, the dielectric layer according to the present invention is characterized by deformation or crushing due to mechanical impact such as collision, so that flat or elongated crystals are unlikely to exist, and the crystallite shape is roughly granular. As you can see, the aspect ratio is about 2.0 or less. Further, since it is a rejoined portion of fragmented particles, it has no crystal orientation and is almost dense, so it has excellent mechanical and chemical properties such as hardness, wear resistance, and corrosion resistance.

 Further, in the present invention, from the crushing of the raw material fine particles to the re-bonding is instantaneously performed, the atoms are hardly diffused near the surface of the fine fragment particles at the time of bonding. Therefore, the atomic arrangement at the interface between the crystallites of the dielectric layer is not disturbed, and the grain boundary layer (glass layer) which is a dissolved layer is hardly formed, and even if formed, it is 1 nm or less. Therefore, it shows the characteristics excellent in chemical characteristics such as corrosion resistance.

 That is, in the semiconductor manufacturing process, the manufacturing apparatus may be cleaned using a corrosive gas, and the electrostatic chuck is exposed to the corrosive gas. Of the dielectric layers made of polycrystalline ceramic, The interfacial interface, that is, the glass layer at the grain boundary, is most easily corroded, and thus the glass layer is etched to degrade the accuracy of the surface of the dielectric layer. This deteriorates the wear resistance of the electrostatic chuck and shortens the life of the chuck. In the present invention, by eliminating the glass layer at the interface between crystallites at all, or by suppressing the thickness of the glass layer to 1 nm or less, it is possible to improve the corrosion resistance and delay the deterioration of the characteristics of the electrostatic chuck.

 According to another aspect of the structure of the electrostatic chuck according to the present invention, the above-described electrostatic chuck is characterized in that the substrate has a cooling function. When an etching operation is performed on a chucked wafer, the wafer surface is heated, and thus it is necessary to control the wafer to a constant process temperature while cooling the wafer. Usually, an electrostatic chuck is attached to a liquid-cooled cooling plate made of an aluminum alloy material or the like by indium bonding or the like, or fixed with bolts, and the temperature of the cooling plate is lowered to lower the temperature of the wafer via the electrostatic chuck. Although temperature control is performed, in the present invention, the ceramic dielectric layer having the above-described characteristics is formed on the cooling plate, and the cooling plate itself has the chuck characteristics, so that the cooling efficiency is remarkably improved. In this case, a cooling plate can be used as an electrode.

 In another aspect of the structure of the electrostatic chuck according to the present invention, in the ceramic dielectric layer, a metal element or a semi-metal element other than the main element constituting the crystallite is present at the interface between the crystallites. It is characterized by not being segregated. In a ceramic sintered body or the like, a sintering aid segregates at the interface between crystallites, which causes deterioration of corrosion resistance or wear resistance. Segregated metal elements adhere to the wafer and cause contamination. The present invention does not have these concerns.

 In another aspect of the structure of the electrostatic chuck according to the present invention, the ceramic dielectric layer described above is mainly composed of aluminum oxide and preferably has a purity of 99% or more. Aluminum oxide has good mechanical properties, electrical properties, and chemical properties as an electrostatic chuck application, and is a material that is often used in conventional electrostatic chucks. In the past, due to restrictions on the manufacturing process, even if aluminum oxide was the main component, it was not possible to make full use of the characteristics of the material due to the inclusion of a sintering aid in it or a porous material. . By using this material to form a fine polycrystalline dense dielectric layer as described above, it is possible to further improve wear resistance, surface smoothness, insulation and corrosion resistance.

 These properties can be further improved by increasing the purity of the aluminum oxide. If impurities are not present, there is no worry of contamination of the wafer by them.

 In some cases, the dielectric layer may be a solid solution of aluminum oxide and titanium oxide. By adding this element, which has a slightly lower electrical resistivity than aluminum oxide, it is easy to develop the Johnsen-Rahbek force, that is, it is possible to improve the adsorption force of the electrostatic chuck.

 In some cases, the dielectric layer is one of the components constituting silicon nitride, silicon carbide, aluminum nitride, zirconium oxide, silicon oxide, chromium oxide, calcium oxide, magnesium oxide, strontium oxide, barium oxide, boron nitride or these. Including a combination of These are selected and added according to purposes such as improvement of wear resistance, control of electrical resistivity, and improvement of corrosion resistance.

 In another aspect of the electrostatic chuck structure according to the present invention, the amount of oxygen in the dielectric layer is controlled, and the composition of the dielectric layer is a non-stoichiometric composition based on oxygen deficiency or excess. Features.

 For example, when aluminum oxide is used as a constituent component of the electrostatic chuck, almost no current flows because aluminum oxide has a high electrical resistivity. This means that the Coulomb force can only be used for the chuck force, and it is difficult to generate a sufficient adsorption force at a low voltage. Control the amount of elements such as oxygen in the composition of the dielectric layer, and in particular cause oxygen to be deficient or excessively present at the grain boundaries to cause a deviation from the stoichiometric composition, or water as a compound containing oxygen It is conceivable that by making modifications such as adsorbing to the structure of the dielectric layer, particularly to the grain boundary, or chemically bonding as a hydroxyl group, the electrons can easily move. Therefore, when a voltage is applied, a very small current flows along the vicinity of the grain boundary. This means that the Johnsen-Rahbek effect is manifested, and it is possible to form a ceramic dielectric layer having a high adsorptive power with high-purity aluminum oxide without the need to add an element with low electrical resistivity. As a result, there is no fear of wear resistance, corrosion resistance deterioration and wafer contamination due to the additive, and a large adsorption force can be obtained even at a low voltage. Further, since the crystallite is fine, the total interface area is large, that is, it is possible to take many routes through which current flows, which is an advantage of the fine polycrystal.

 In one aspect of the electrostatic chuck according to the present invention, the thickness of the ceramic dielectric layer is 50 μm or less, desirably 30 μm or less. For example, when high-purity aluminum oxide is used as the ceramic dielectric layer, the electrical resistance value is high, so if the layer thickness is relatively thick, the Coulomb force cannot be expressed effectively, and the adsorption power cannot be increased accordingly. . Further, if the layer thickness is large, the thermal conductivity is also inferior, which causes a decrease in the cooling efficiency of the wafer and a disturbance in the temperature distribution. For example, by setting the thickness of the dielectric layer made of aluminum oxide to 50 μm or less, preferably 30 μm or less, an electrostatic chuck having a large adsorption force even under a low voltage, excellent thermal conductivity, and low wafer contamination can be obtained. It is done.

 In one aspect of the electrostatic chuck according to the present invention, the surface of the ceramic dielectric layer is ground or / and polished. In various processing of wafers, it is important to maintain the flatness of the wafer during the process. Therefore, the flatness of the dielectric layer of the electrostatic chuck that holds the wafer is required. Sufficient flatness can be achieved by performing ultraprecision grinding or polishing on the surface of the electrostatic chuck.

 In some cases, because the flatness of the dielectric layer is excellent, when a wafer with a large area is attracted, the attracting force is too strong, and a large force may be required when removing the wafer after various processing. There is even a risk of destruction. In such a case, it is preferable to control the suction force by controlling the effective suction area by forming irregularities in the dielectric layer.

 On the other hand, in the manufacturing method of the electrostatic chuck of the present application, the brittle material fine particles are first subjected to pretreatment to give internal strain to the brittle material fine particles, and then the brittle material fine particles stored with the internal strain collide with the substrate surface at high speed. Or by applying a mechanical impact force to the brittle material fine particles that store internal strain accumulated on the surface of the base material, deforming or crushing the brittle material fine particles, and forming an active new surface generated by the deformation or crushing. By recombining the fine particles with each other, an anchor portion made of a polycrystalline brittle material that partially penetrates the surface of the base material is formed at the boundary with the base material, and the polycrystalline brittle material is further formed on the anchor portion. A dielectric made of is formed.

 If the internal strain is small, it is difficult to be deformed or crushed when the brittle material fine particles collide. Conversely, if the internal strain increases, a large crack is generated to cancel the internal strain. Even if these aggregates collide with the base material, a new surface is hardly formed. Therefore, in order to obtain the electrostatic chuck according to the present invention, the particle size and the collision speed of the brittle material fine particles are important, but more than that, it is necessary to give the raw material brittle material fine particles in advance within a predetermined range. is important. The most preferred internal strain is a strain that has increased until just before the crack is formed, but any fine particles may be used as long as the internal strain remains even if some cracks are formed. For the pulverization treatment that distorts the fine particles, it is preferable to use a pulverizing means that can give a large impact for the pulverization of the fine particles. This is because a large strain can be imparted to the fine particles relatively uniformly. As such a pulverizing means, it is preferable to use a vibration mill, an attritor, or a planetary mill that can give a large acceleration of gravity compared to a ball mill often used for pulverizing ceramics. Most preferably, a planetary mill that can provide acceleration is used.

 Examples of the method of causing the brittle material fine particles to collide at high speed include a method using a carrier gas, a method of accelerating the fine particles using an electrostatic force, a thermal spraying method, a cluster ion beam method, and a cold spray method. Of these, the method using a carrier gas is conventionally called the gas deposition method, in which an aerosol containing fine particles of metal, metalloid, or ceramic is ejected from a nozzle and sprayed onto a substrate at a high speed to deposit the fine particles on a substrate. In this structure forming method, a dielectric layer is formed to form a deposited layer such as a green compact having a fine particle composition.

 Of these, the method of directly forming a structure on a substrate is called an ultra-fine particle beam deposition method or an aerosol deposition method, and in this specification, the fabrication method according to the present invention is referred to. Hereinafter, this name is used.

 In the electrostatic chuck manufacturing method (ultrafine particle beam deposition method) according to the present invention, it is preferable that the brittle material fine particles have an average particle diameter of 0.1 to 5 μm and have a large internal strain in advance. These conditions are closely related to whether a new surface is formed when the substrate is caused to collide with the substrate. If the particle size is less than 0.1 μm, the particle size is too small to cause crushing or deformation. When the thickness exceeds 5 μm, although partial crushing occurs, the effect of removing the film by etching appears substantially, and there are cases where the deposition of the green compact of fine particles is stopped without crushing. Similarly, when the structure is formed with this average particle size, a phenomenon in which the green compact is mixed in the structure is observed at 50 m / s or less, and the etching effect becomes noticeable at 450 m / s or more. It has been found that structure formation efficiency is reduced. Furthermore, these inconveniences are better solved when the ratio is in the range of 150 to 400 m / s or less. Here, the speed of the fine particles is calculated by the speed measurement method described in Example 3 below.

 In addition, when a crack occurs in the raw material particles, the internal strain is canceled, so it is preferable that there is no crack. However, even if there is a crack, it is sufficient that a predetermined internal strain exists. In other words, the raw material fine particles in which the internal strain is accumulated until just before the crack is generated are most preferable.

 When the content disclosed in Japanese Patent Application Laid-Open No. 2000-212766 has been re-examined, the above-mentioned conditions may not have been satisfied because brittle materials such as ceramics have not necessarily obtained good results.

 In another aspect of the method for producing an electrostatic chuck according to the present invention, after the step of controlling the amount of oxygen contained in the brittle material fine particles, the brittle material fine particles whose oxygen amount is controlled are then applied to the substrate surface. The brittle material fine particles are deformed or crushed by applying a mechanical impact force to the brittle material fine particles with controlled oxygen amount, which are collided at a high speed or on the surface of the substrate. By recombining the fine particles with each other through the newly formed active surface, an anchor portion made of a polycrystalline brittle material that partially bites into the base material surface is formed at the boundary with the base material. A dielectric made of a polycrystalline brittle material is formed on the substrate.

 The oxygen contained in the brittle material fine particles is an oxygen atom or a compound containing oxygen, such as water or a hydroxyl group, and the brittle material fine particles in a state in which they are adsorbed or bonded to the surface of the fine particles are prepared. In this method, for example, it is effective to perform a mechanochemical action in an environment where water vapor is present, or a treatment using an apparatus such as a ball mill, a vibration mill, or a planetary mill. In particular, oxygen can be adsorbed more efficiently by a dry process. By forming a dielectric layer using these fine particles of brittle material with controlled oxygen content as a raw material, the amount of oxygen in the dielectric layer can be made excessive, which changes electrical characteristics such as volume resistivity. It is thought that it can be made.

 One of the features of the manufacturing method of the electrostatic chuck according to the present invention is that it can be performed at room temperature or at a relatively low temperature, and a material having a low melting point such as a resin can be selected as the base material. However, a heating step may be added in the method of the present invention. For example, when the actual usage condition of the electrostatic chuck is a high temperature of several hundred degrees, the thermal stress due to the difference in thermal expansion between the substrate and the ceramic dielectric layer can be reduced by making the temperature during the formation of the ceramic dielectric layer the same. It is preferable that the temperature is canceled at this temperature. Further, after forming the dielectric layer made of the polycrystalline brittle material, it is possible to control the crystal structure by heat treatment at a temperature lower than the melting point of the brittle material.

 In the method of manufacturing an electrostatic chuck according to the present invention, it is preferable to carry out the process under reduced pressure in order to maintain the activity of the new surface formed on the raw material fine particles for a certain period of time.

 Further, when the manufacturing method of the electrostatic chuck according to the present invention is performed by the ultrafine particle beam deposition method, the kind of the carrier gas and / or the partial pressure is controlled to form the dielectric layer made of the brittle material. By controlling the element amount of the compound, controlling the oxygen concentration in the dielectric layer, or forming an oxygen-deficient layer or excess layer of the oxide near the crystal interface in the dielectric layer, It is conceivable to control electrical characteristics, mechanical characteristics, chemical characteristics, optical characteristics, and magnetic characteristics.

 That is, for example, when an oxide such as aluminum oxide is used as a raw material fine particle of the ultrafine particle beam deposition method and the dielectric layer is formed while suppressing the oxygen partial pressure of the gas used for this, the fine particle is crushed and the fine fragment particle When formed, it is conceivable that oxygen escapes from the surface of the fine fragment particles into the gas phase and oxygen deficiency occurs in the surface phase. If this happens, since the fine fragment particles are rejoined thereafter, an oxygen deficient layer is formed in the vicinity of the interface between the crystal grains. Also, the element to be deficient is not limited to oxygen, but may be nitrogen, boron, carbon, etc. These also control the gas partial pressure of a specific gas type, depending on the non-equilibrium state of the element amount between the gas phase and the solid phase It is conceivable that element dropout occurs due to distribution or reaction.

In another aspect of the method for manufacturing an electrostatic chuck according to the present invention, one or more electrodes are formed through an insulating layer at a position where the chuck layer of the substrate is covered, and then an ultrafine particle beam deposition method is performed on the electrode layer. Then, a ceramic dielectric layer is formed with a thickness of 1 μm to 50 μm, and then the ceramic dielectric layer is ground and / or polished from the surface to form a chuck layer with a thickness of 0.5 μm to 30 μm.

 In the case of using an insulator as a substrate, a conductive electrode is previously formed on the substrate by means of printing, vapor deposition, plating, etc., and a ceramic dielectric layer is formed thereon by an ultrafine particle beam deposition method. Can do. This method is suitable when two or more electrodes are required.

 In another aspect of the method for manufacturing an electrostatic chuck according to the present invention, one or more electrodes are formed on the chuck layer coating position of the substrate via the insulating layer, and then the insulator is covered so as to cover the chuck layer coating position. The layer is formed with a thickness of 5 μm or less, then the ceramic dielectric layer is formed with a thickness of 1 μm to 50 μm by ultrafine particle beam deposition, and then the ceramic dielectric layer is ground and / or polished from the surface to a thickness of 0. A chuck layer of 5 to 30 μm is formed.

 When it is desired to use a metal material having excellent thermal conductivity as the substrate, it is difficult to use the substrate as a plurality of electrodes because of its conductivity. Therefore, after forming an insulating film on the metal substrate in advance, a necessary number of electrodes are formed, and a ceramic dielectric layer is formed by an ultrafine particle beam deposition method. For the formation of the insulating film, an ultrafine particle beam deposition method may be used, or a sol-gel method, PVD, CVD method, or the like may be used. A thinner one of these insulator films is preferable because of excellent heat conduction.

 In the ultrafine particle beam deposition method, the dielectric layer is formed while changing the relative position between the nozzle to which the powder is sprayed and the substrate. However, by controlling the film forming speed such as the relative speed between the nozzle and the substrate, It is easy to control the deposition thickness of the ceramic dielectric layer. As described above, in some cases, it is effective to make the ceramic dielectric layer uneven, and the thickness may be controlled as necessary. For example, a method of forming a ceramic coating as a thin film coating for the purpose of improving the corrosion resistance of a substrate in a region that does not participate in the adsorption is formed in a region that is used for the adsorption to have a necessary adsorption force. Can be adopted.

 In one aspect of the method for manufacturing an electrostatic chuck according to the present invention, the electrostatic chuck manufactured by the method for manufacturing an electrostatic chuck as described above is subjected to heat treatment at a temperature below the melting point of the substrate and the ceramic dielectric layer. This causes crystallite grain growth in the ceramic dielectric layer.

 The ceramic dielectric layer formed by the ultrafine particle beam deposition method is characterized by its extremely small crystallite diameter, but hardness, wear resistance, internal strain, corrosion resistance, dielectric constant, dielectric breakdown voltage, electrical resistance In order to set various characteristics such as values to desired values, the dielectric layer may be heat-treated.

 In one aspect of the method for manufacturing an electrostatic chuck according to the present invention, a mask is disposed on the surface of the electrostatic chuck manufactured by the above-described manufacturing method, blasting is performed, and an arbitrary shape is formed on the ceramic dielectric layer. Unevenness is formed.

 In addition to the method of forming irregularities and spots on the surface of the ceramic dielectric layer by the ultrafine particle beam deposition method, it is also effective to perform blasting and etching to make the surface irregular again after the ceramic dielectric layer is formed It is. This makes it possible to optimize the adsorption force.

 In one aspect of the method for manufacturing an electrostatic chuck according to the present invention, a cooling plate having a cooling function is used for a substrate. In particular, a metal mainly composed of copper or aluminum is used.

 Use of copper or aluminum having good thermal conductivity for a cooler of a semiconductor manufacturing apparatus is convenient for improving its performance. Even at present, aluminum alloys are used. By using the surface of this cooler on the substrate on which the ceramic dielectric layer is formed by ultrafine particle beam deposition, the structure is simplified and the presence of unstable elements such as the adhesive layer between the cooler and electrostatic chuck is eliminated. In addition, an electrostatic chuck with a cooling function having excellent thermal conductivity can be manufactured.

 In one aspect of the method for manufacturing an electrostatic chuck according to the present invention, the ceramic fine particles used in the ultrafine particle beam deposition method are aluminum oxide having a purity of 99% or more. The purity is expressed by weight% as a conversion amount of aluminum oxide with respect to the oxide conversion amount of the total amount including magnesium, silicon, iron, etc., which may be included in addition to aluminum, by wet mass spectrometry. It means the abundance of aluminum in the cation. Further, in some cases, the powder composed of ceramic fine particles used may be converted into aluminum oxide, titanium oxide, silicon nitride, silicon carbide, aluminum nitride, zirconium oxide, silicon oxide, chromium oxide, calcium oxide, magnesium oxide, strontium oxide, oxidation A mixed powder of two or more kinds of barium and boron nitride or a powder made of two or more kinds of solid solutions is used.

 When it is desired to apply 99% or more high-purity aluminum oxide to the ceramic dielectric layer, this purity is achieved by using an aluminum oxide having a purity of 99% or more as a raw material powder and forming it by an ultrafine particle beam deposition method. Can be kept strictly. The ultrafine particle beam deposition method does not cause a deviation in element ratio due to element evaporation due to heating unlike firing. There is no inconvenience that a product having a desired composition can be obtained only by finely controlling the environment such as gas type and pressure as in PVD and CVD. If the composition of the powder is controlled in advance, a composition having a composition according to the powder composition can be obtained.

  As described above, in the electrostatic chuck according to the present invention, the dielectric layer formed on the substrate is polycrystalline, the crystals constituting the dielectric layer have substantially no crystal orientation, and the crystal There is virtually no glassy grain boundary layer at the interface between them, and a part of the dielectric layer is an anchor part that bites into the substrate surface. Excellent in electrical and electrochemical properties.

 Further, according to the manufacturing method of the electrostatic chuck according to the present invention, since the dielectric layer is formed by ejecting the raw material brittle material fine particles having internal strain to the surface of the substrate at a high speed, it is easy and within a short time. An electrostatic chuck can be manufactured.

FIG. 1 shows a configuration diagram of a cooling plate integrated electrostatic chuck 1 as one aspect of the electrostatic chuck according to the present invention. The cooling plate-integrated electrostatic chuck 1 has an alumina chuck layer 12 which is a ceramic dielectric layer having a maximum thickness of 10 μm made of aluminum oxide with a purity of 99.8% on a cooling plate 11 whose upper surface is made of brass and is flat. Have. The alumina chuck layer 12 has a structure in which a plurality of spot-like chuck portions 10 mm in length and width are scattered in a thickness of 7 μm on a thin film layer having a thickness of 3 μm. The alumina chuck layer 12 has a porosity of 1% or less, and the average crystallite diameter is 9.8 nm as calculated by the Scherror & Hall Method calculation formula of the X-ray diffraction method. In the TEM observation of this structure shown in FIG. 2, it is confirmed that granular crystallites of about 10 nm are distributed in disordered orientation and joined to each other. ) Is not seen. The upper surface of the spot-like chuck portion is flat and has sufficient flatness. The inside of the cooling plate 11 is hollow, and a cooling medium 13 such as florinate flows through the cooling plate 11. The arrows in the figure indicate the flow of the cooling medium 13. A wafer 14 is placed on the alumina chuck layer 12. The cooling plate 11 constitutes one end of the electrode, is connected to the power source 15, and is electrically wired so that the conductive wire contacts the wafer 14.

 The action and effect of this electrostatic chuck will be described. The wafer 14 is transferred onto the cooling plate integrated electrostatic chuck 1 installed in a semiconductor manufacturing apparatus (not shown) by a wafer moving arm (not shown). By installing a conductive wire on the wafer 14 and switching on the power supply connected thereto, a quasi-electrostatic attractive force acts between the wafer 14 and the cooling plate 11 serving as an electrode via the alumina chuck layer 12. Is firmly fixed to the cooling plate integrated electrostatic chuck 1 while maintaining good flatness. As shown in FIG. 3, the adsorption force at this time shows, for example, about 2000 gf / cm 2 when a voltage of 200 V is applied in vacuum, and the adsorption force responsiveness when the voltage is turned on reaches a constant value within a few seconds. Very good. A semiconductor manufacturing process such as an etching operation is performed from the upper surface of the wafer 14 while flowing the cooling medium 13 maintained at 25 ° C. through the cooling plate 11. At this time, a heat amount of several kW is applied to the wafer 14, but the alumina chuck layer 12, which is an extremely thin film of 10 μm, exhibits good heat conduction characteristics, and heat conduction between the alumina chuck layer 12 and the cooling plate 11. Therefore, the cooling effect of the cooling medium 13 is sufficiently received and the wafer 14 is efficiently cooled, the process temperature is lowered, and the non-uniform temperature distribution in the surface of the wafer 14 is obtained. Is also suppressed. This decrease in the process temperature suppresses the thermal expansion of the wafer 14, thereby reducing the frictional wear due to the thermal expansion at the interface between the alumina chuck layer 12 and the wafer 14 and improving the life of the alumina chuck layer 12. . Further, because of the alumina chuck layer 12 using high-purity aluminum oxide, the wear resistance is also good and there is no impurity contamination of the wafer 14 due to frictional wear.

 After the operation such as etching is completed, the power supply is turned off and the wafer 14 is removed to complete the series of processes. However, since the electrostatic chuck of this embodiment uses high-purity aluminum oxide, it has an attractive force. There is little dependence on the Johnsen-Rahbek effect in the expression, and the time until the adsorption is released when the power is turned off is extremely short, within one second, and the process time can be shortened.

In FIG. 1, the cooling plate 11 is in a state in which the brass material is exposed. However, when there is a concern about deterioration of the material during cleaning using a corrosive gas or the like of a semiconductor manufacturing apparatus, the surface portion of the brass is corrosion-resistant. It is preferable to cover with a member.

 FIG. 4 shows the configuration of the manufacturing apparatus 2 for the cooling plate-integrated electrostatic chuck 1. In the manufacturing apparatus 2, an XY stage 203 that can be programmed is installed in a vacuum chamber 202 connected to a vacuum pump 201, and a cooling plate 204 (equivalent to 11 in FIG. 1) is installed on the stage. A film-forming nozzle 206 having a nozzle mask 205 is disposed opposite to the alumina chuck layer coating position of the cooling plate 204, which is disposed outside the vacuum chamber 202 via the aerosol transport pipe 207, and contains aluminum oxide fine particles. It is connected to an aerosol generator 208 that generates aerosol. The aerosol generator 208 is connected to the nitrogen gas cylinder 210 via the gas transport pipe 209.

FIG. 5 shows a perspective view of the tip of the film forming nozzle 206. The tip of the film forming nozzle 206 has an opening with a major axis of 10 mm and a minor axis of 0.4 mm, and a nozzle mask 205 having a slit opening with a width of 9.5 mm is disposed in the space portion at the tip of the opening.

Next, a manufacturing process of the cooling plate integrated electrostatic chuck by the manufacturing apparatus 2 will be described. In a state where the vacuum pump 201 is operated and the inside of the vacuum chamber 202 is maintained at about several kPa, the nitrogen gas cylinder 210 is opened, and nitrogen gas is fed into the aerosol generator 208 at a predetermined flow rate so that the internal pressure is about 350 kPa. The aerosol generator 208 mixes aluminum oxide particles with nitrogen gas to generate aerosol, which is accelerated by the aerosol transport pipe 207, and the velocity of the aluminum oxide particles in the aerosol is increased from the opening at the tip of the film forming nozzle 206. Injected toward the alumina chuck layer coating position of the cooling plate 204 at a subsonic speed. The aluminum oxide particles collide with the alumina chuck layer coating position at the speed as described above, and after being crushed into fine fragment particles, they are recombined instantly and deposited at this position as a fine crystallite joint. The film is formed. Is that this is not a green compact is the deposition of a mere powder, the hardness of alumina chucking layer is 1000 kgf / mm ² or more in Vickers hardness from about 700 kgf / cm ² in the adhesion between the cooling plate 204 It is clear from the fact that the value of is confirmed.

In the situation where aerosol collides and film formation is performed, in addition to the generation of fine fragment particles as described above and subsequent instantaneous bonding, etching (film scraping) by collision of aluminum oxide particles with the film surface, Phenomenon such as adhesion and detachment of partially aggregated aluminum oxide particles to the film surface occurs simultaneously. That is, there are coexisting factors that inhibit film formation, and eliminating these adverse factors is an important factor for improving the film-forming speed and cleaning the film-forming surface. In the present invention, the aerosol injection direction is inclined at an angle of 30 ° with respect to the vertical direction of the alumina chuck layer coating position. This is suitable as a means for reducing the adhesion of aluminum oxide particles to the film surface. When the angle is 0 °, crater-like depressions are formed on the film surface due to the adhesion, whereas the angle is 15 ° to 45 °. It has been experimentally confirmed that the formation of the crater-like recess is remarkably reduced.

The velocity of the aluminum oxide particles in the aerosol sprayed from the film forming nozzle 206 has a velocity distribution within the opening surface of the nozzle, and the vicinity of the wall surface when the central portion of the opening is controlled at a speed suitable for film formation. Then it will be slower. Accordingly, the film forming property is not good at the nozzle peripheral part, that is, the place corresponding to the peripheral part of the film forming part of 10 mm in length and 0.4 mm in width. During the film forming operation, the XY stage 204 is programmed to form an alumina chuck layer in a required area while changing the relative position with the film forming nozzle 206. Although a large area is secured while gradually shifting the film forming part of 10 mm in length and 0.4 mm in width, the film is overlaid on the peripheral part of the film forming part inferior in film forming property. The alumina chuck layer thus obtained has poor adhesion to the cooling plate 204 and may cause peeling at the interface with the alumina chuck layer. In order to solve this, a nozzle mask 205 is disposed at the tip of the film forming nozzle 206 to provide a mechanism for excluding aluminum oxide particles around the slow nozzle. In the case of the present invention, a mask is provided on the side of the nozzle periphery, that is, on the short side. However, if the nozzle mask is rectangular and both the long side and the short side are masked and all particles having a low speed are excluded, the effect is further improved. That is, it is possible to obtain an alumina chuck layer having excellent adhesion.

In order to form the alumina chuck layer in a spot shape, first, a film is formed on the entire surface of the chuck layer covering position by a program operation that results in a film thickness of 3 μm. Thereafter, the film forming nozzle 206 is moved to a spot forming position, and a program operation is performed at this position to form a film having a length and width of 10 mm and a height of 7 μm or more to form a spot. Of course, the shape of the spot is not limited to this, and it may be circular. The spot area is also arbitrary.

In this embodiment, nitrogen gas is used as the gas to be used, but the gas type is not limited to this, and oxygen, helium, argon, hydrogen, air, and the like can be used.

The cooling plate having the alumina chuck layer thus obtained is removed from the manufacturing apparatus 2, ground and polished from the surface by a grinding and polishing machine (not shown), and the cooling plate integrated electrostatic in which the spot surface is distributed with sufficient flatness. Achieved as a chuck 1. Spot formation is suitable not only for reducing time and cost by reducing the amount of film formation, but also for controlling adsorption force and heat conduction characteristics by arbitrarily controlling the contact area with the wafer. . Further, spot formation may be performed, for example, by forming an alumina chuck layer having a thickness of 10 μm, then placing a mask on the surface, and performing blasting treatment by sandblasting or the like leaving a spot portion.

Here, a liquid-cooled cooling plate is used, but an air-cooled case is also conceivable. In this case, the cooling plate has a disk shape, for example, and the alumina chuck layer is disposed in a spot shape as in the first embodiment, and a ventilation hole through which the cooling plate passes is provided in a spot-free portion. The wafer can be cooled by flowing a cooling gas such as helium gas using this vent and filling the gap between the wafer and the alumina chuck layer with this cooling gas.

 FIG. 6 shows a configuration diagram of a cooling plate-integrated electrostatic chuck 3 as another embodiment of the present invention. The cooling plate-integrated electrostatic chuck 3 has an insulating layer 32 made of silicon oxide disposed on a cooling plate 31 whose brass upper surface is circular and flat, and two electrode electrodes 33a and 33b are disposed thereon. An alumina chuck layer 34, which is a ceramic dielectric layer having a thickness of 10 μm and made of aluminum oxide having a purity of 99.8% and having sufficient flatness, is disposed so as to cover the surface. The inside of the cooling plate 31 is hollow, and the cooling medium 35, for example, fluorinate flows through the inside of the cooling plate 31. The arrows in the figure indicate the flow of the cooling medium 35. The electrodes 33a and 33b are connected to a power source 36 through conductive wires. A wafer 37 is placed on the alumina chuck layer 34.

The action and effect of this electrostatic chuck are the same as those of the above-described cooling plate integrated electrostatic chuck 1. In this case, the electric field generated by the electrodes 33a and 33b is used as a driving force for the attraction force, which is one of the general forms of the electrostatic chuck. The alumina chuck layer 34 may have a spot shape, and the film thickness is also arbitrary. The electrodes 33a and 33b can be easily formed using various conductive materials by various methods such as PVD, CVD, printing, and plating. The electrode thickness is arbitrary, but 10 μm or less is appropriate so as not to greatly affect the formation of the alumina chuck layer 34. The insulating layer 32 can be easily formed by a sol-gel method or a polysilazane method (manufactured by Tonen Corporation). The material is not particularly limited to silicon oxide, and any material can be used as long as insulation can be secured. Of course, the material of the cooling plate 31 is not limited to brass, and any material can be used as long as it is relatively hard and excellent in thermal conductivity. If it is an insulating material, it is not necessary to provide the insulating layer 32.

 (Embodiment 1) It is considered that it is preferable to pre-treat the raw material fine particles used in the above-described cooling plate integrated electrostatic chucks 1 and 2 to form internal strains in advance. The reason is as follows. FIG. 7 shows the results of an experiment conducted on the relationship between the internal strain of the raw material fine particles and the thickness of the structure serving as a dielectric layer formed by the ultrafine particle beam deposition method. In the experiment, aluminum oxide fine particles having a purity of 99.6% were pulverized using a planetary mill to change the characterization of the fine particles, and then a structure was formed on the aluminum substrate by an ultrafine particle beam deposition method. The internal strain of the fine particles was measured by X-ray diffraction, and the amount of strain was determined based on 0% obtained by subjecting the fine particles to thermal aging to remove the internal strain.

 Moreover, the SEM photograph (Hitachi in-lens SEM S-5000) of the microparticles | fine-particles in point A, B, C in FIG. 7 is shown in FIG.8, FIG.9 and FIG.10. It can be seen from FIG. 7 that the internal strain is preferably 0.25% to 2.0%. As shown in FIG. 8, when there is no internal strain, the crack does not occur when there is no internal strain. However, when the internal strain exceeds a certain value, in this case, 2.0% or more, the crack is completely cracked. Are formed, and the fragments that fall off adhere to the surface, resulting in a re-aggregation state as shown in FIG.

(Example 2) This example was conducted for crystal orientation. An aluminum oxide structure having a thickness of 20 μm was formed on a stainless steel substrate by using the ultrafine particle beam deposition method of the present invention using aluminum oxide fine particles having an average particle diameter of 0.4 μm. The crystal orientation of this structure was measured by an X-ray diffraction method (MXP-18 manufactured by Mac Science). The results are shown in Table 1.

 Table 1 shows the integrated intensity calculation results of four peak points of a typical surface shape as an intensity ratio with [hkl] = [113] as 100. From the left, as a result of measuring raw material fine particles with a thin film optical system, as a result of measuring a structure with a thin film optical system, JCPDS card 74-1081 corundum aluminum oxide data, and a result of measuring raw material fine particles with a concentrated optical system are described.

Since the results of the concentrated optical system of the raw material fine particles and the thin film optical system are almost the same, the result of the thin film optical system of the raw material powder is based on the non-oriented state, and the deviation of the strength ratio of the structure at this time is displayed as a percentage It shows in Table 2. On the basis of [113], the deviation of the other three peaks is within 11%, and it can be said that the structure has substantially no crystal orientation.

(Example 3) This example is a result of measuring the velocity of fine particles ejected from a nozzle when a structure is formed by the ultrafine particle beam deposition method. FIG. 11 shows a fine particle velocity measuring apparatus. A nozzle 41 for injecting aerosol into a chamber (not shown) is installed with the opening facing upward, and a substrate 43 installed at the tip of a rotary blade 42 that is rotated by a motor and a substrate surface 19 mm below the substrate surface. A fine particle velocity measuring device 4 having a slit 44 having a notch having a fixed width of 0.5 mm is arranged. The distance from the opening of the nozzle 41 to the substrate surface is 24 mm.

Next, the fine particle velocity measurement method will be described. The aerosol is sprayed according to the actual structure manufacturing method. In place of the substrate on which the structure is formed in the structure forming apparatus, it is preferable to install the fine particle velocity measuring device 4 shown in the figure. A chamber (not shown) is placed under reduced pressure, and after a pressure of several Torr or less, aerosol containing fine particles is ejected from the nozzle 41. In this state, the fine particle velocity measuring device 4 is operated at a constant rotational speed. Part of the fine particles that have jumped out from the opening of the nozzle 41 collide with the surface of the substrate through the gaps in the slit 44 when the substrate 43 comes to the top of the nozzle 41, and the structure ( Collision marks) are formed. Since the position of the substrate 43 is changed by the rotation of the rotary blade 42 while the fine particles reach the substrate surface 19 mm away from the slit, the amount of displacement is larger than the perpendicular crossing position from the notch of the slit 44 on the substrate 43. Collide with the displaced position. The distance from the perpendicular crossing position to the structure formed by the collision is measured by surface unevenness measurement, and using this distance, the distance from the slit 44 and the substrate surface, and the value of the rotational speed of the rotary blade 42, the nozzle 41 is measured. As the velocity of the fine particles ejected from the nozzle 41, the average velocity from a location 5 mm away from the opening of the nozzle 41 to a location 24 mm away was calculated, and this was used as the velocity of the fine particles in this case.

(Example 4) In relation to the present invention, characteristics of a structure corresponding to a dielectric layer of an electrostatic chuck were evaluated. First, using a dry planetary mill under various pulverization conditions in the atmosphere, aluminum oxide fine particles having an average particle size of 0.6 μm and a purity of 99.8% are pulverized and pretreated, and four types of treated fine particles are prepared. Using these, an aluminum oxide structure having a formation height of approximately 10 μm was formed on a metal substrate by an ultrafine particle beam deposition method. The composition ratio of O / Al, which is the ratio of oxygen to aluminum in the aluminum oxide structure formed in FIG. 12, and the volume resistivity (volume resistivity value) when the aluminum oxide structure was measured with a voltage of 100 V applied. ) Is plotted. The O / Al composition ratio and volume resistivity were measured by providing a circular electrode with a diameter of 13 mm on an aluminum oxide structure and an external electrode having a 1 mm width electrode on the outside with a 1 mm gap on the circumference. Prepare a sample, apply a voltage of 100 V between the circular electrode and the conductive base material, ie, the lower electrode, leave it for about 30 seconds after application, read the stable current value with a microammeter, Was obtained by Ohm's law. For comparison, the O / Al composition ratio and volume resistivity of the aluminum oxide sintered body fired at 1700 ° C. are also plotted.

In the aluminum oxide structure formed by the above-described structure forming method, the volume resistivity value tended to decrease as the O / Al composition ratio increased. For example, in an aluminum oxide structure having an O / Al composition ratio of 0.049, the volume resistivity decreases from 10 ¹⁴ Ω · cm to 10 ⁸ Ω · cm as compared to 0.044 of the aluminum oxide fired body, This suggested that it became easier to carry electricity.

Configuration diagram of electrostatic chuck with integrated cooling plate TEM image of dielectric layer structure Graph showing the relationship between applied voltage and adsorption force Overall view of cooling plate integrated electrostatic chuck manufacturing equipment Perspective view of nozzle tip Configuration diagram of electrostatic chuck with integrated cooling plate according to another embodiment Graph showing the relationship between internal strain and film thickness of the raw material used SEM image of fine particles corresponding to point A in FIG. SEM image of fine particles corresponding to point B in FIG. SEM image of fine particles corresponding to point C in FIG. Particle velocity measuring device Relationship between O / Al composition ratio and volume resistivity value in aluminum oxide structure according to Example 4

Explanation of symbols

      DESCRIPTION OF SYMBOLS 1 ... Cooling plate integrated electrostatic chuck, 11 ... Cooling plate, 12 ... Alumina chuck layer (dielectric layer), 13 ... Cooling medium, 14 ... Wafer, 15 ... Power supply. DESCRIPTION OF SYMBOLS 2 ... Manufacturing apparatus, 201 ... Vacuum pump, 202 ... Vacuum chamber, 203 ... XY stage, 204 ... Cooling plate, 205 ... Nozzle mask, 206 ... Film-forming nozzle, 207 ... Aerosol transport pipe, 208 ... Aerosol generator, 209 ... Gas transport pipe, 210 ... nitrogen gas cylinder. DESCRIPTION OF SYMBOLS 3 ... Cooling plate integrated electrostatic chuck, 31 ... Cooling plate, 32 ... Insulating layer, 33a, 33b ... Electrode, 34 ... Alumina chuck (dielectric layer), 35 ... Coolant, 36 ... Power supply, 37 ... Wafer.

Claims (4)

 In the electrostatic chuck in which a dielectric layer is formed on a surface of a conductive substrate and a voltage is applied to the substrate to cause an adsorption action between the substrate and an object to be adsorbed via the dielectric layer. The layer is made of a polycrystalline brittle material and is directly bonded to the surface of the substrate, and there is substantially no grain boundary layer made of a glass layer at the interface between the crystals, and a part of the dielectric layer Is an anchor portion that bites into the substrate surface, and the dielectric layer has an average crystallite diameter of 500 nm or less and a density of 70% or more.  A dielectric layer is formed on the surface of a substrate provided with a plurality of electrodes on an insulator. By applying a voltage to the electrodes, an adsorbing action is generated between the substrate and an object to be adsorbed via the dielectric layer. In the electrostatic chuck, the dielectric layer is made of a polycrystalline brittle material and directly bonded to the surface of the substrate, and there is substantially no grain boundary layer made of a glass layer at the interface between the crystals, Further, a part of the dielectric layer serves as an anchor portion that bites into the substrate surface, and the dielectric layer has an average crystallite diameter of 500 nm or less and a density of 70% or more. Electric chuck.   The electrostatic chuck according to claim 1, wherein the dielectric layer has an average crystallite diameter of 100 nm or less and a density of 95% or more. The electrostatic chuck according to claim 1, wherein the dielectric layer has an average crystallite diameter of 50 nm or less and a density of 99% or more.

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