JP2006270084A - Electrostatic chuck, wafer holding element and method of processing wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic chuck adapted to cause a small temperature difference in a wafer surface and to have a small removal response characteristic and gas leakage while retaining a temperature uniformity in the substrate and a high attraction power, and also to provide a wafer holding element using the chuck. <P>SOLUTION: The electrostatic chuck 1 is provided with: a plate-like ceramic body 2 with one of the major surfaces adapted to mount a matter to be held W as a mounting surface 3 and the other major surface or the interior portion provided with an electrode 6 for electrostatic attraction, wherein a circular protrusion 3a is provided in the peripheral portion of the mounting surface 3; a circular depression is provided inside the circular protrusion; a gas-filling surface 3b is provided inside the circular depression; a gas supply hole 5 for communicating with the circular depression is provided; and the ratio of the difference between the maximum value Ra (max) and the minimum value Ra (min) of the arithmetic average roughness Ra of the circular protrusion 3a to the maximum value Ra (max), that is (Ra(max)-Ra(min))/Ra(max), is set to 0.2 or less. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wafer holding member such as an electrostatic chuck in an apparatus for manufacturing a semiconductor element or a liquid crystal display panel. The wafer holding member is used for fixing a wafer W such as a semiconductor wafer or a glass substrate for liquid crystal.

  In the semiconductor manufacturing process, in order to accurately perform processing such as film formation and etching on the wafer W such as the silicon wafer W, it is necessary to maintain the wafer W while maintaining the flatness. Conventionally, mechanical, vacuum chuck, and electrostatic chuck type wafer holding members have been proposed as such holding means.

  Among these holding means, the electrostatic chuck type wafer holding member that holds the wafer W by electrostatic force can easily realize the flatness of the wafer W required for various processes such as film formation and etching. . In particular, this electrostatic chuck can be used in a vacuum or in a corrosive gas atmosphere. Therefore, electrostatic chuck type wafer holding members are frequently used in film forming apparatuses and etching apparatuses.

  By the way, with the improvement of the degree of integration of semiconductor elements, there is a strong demand for stabilization of characteristics of semiconductor elements, improvement of yield, increase in the number of processed sheets per unit time, and the like. For this reason, it is required to heat the wafer W to the target temperature as quickly as possible during etching or film formation processing to improve the thermal uniformity of the entire surface of the wafer W.

  Accordingly, attempts have been made to improve the heat transfer characteristics between the wafer W and the electrostatic chuck and to make the surface temperature of the wafer W uniform. In order to improve the heat transfer characteristics between the wafer W and the electrostatic chuck, a gas supply hole for introducing an inert gas such as He or Ar to the mounting surface on which the wafer W is placed, and the gas supply hole communicate with the gas supply hole. Forming grooves or recesses. Then, when the wafer W is adsorbed on the mounting surface from the gas supply hole, an inert gas is filled into the space formed by the wafer W and the groove or recess.

  For example, Patent Documents 1, 2, and 3 describe the groove shape and the concave shape formed on the mounting surface. In these documents, as shown in FIG. 6, a gas supply hole 34, a plurality of radial grooves 35 communicating with the gas supply hole 34, and each radial groove are formed on the upper surface of a disk-shaped electrostatic chuck 31. 35 and a return groove 36 disposed concentrically at substantially equal intervals around the gas supply hole 34, and 13 to 133 Pa of helium gas is introduced into the gas supply hole 34. An electrostatic chuck 31 is disclosed in which the upper surface excluding the radial grooves 35, the annular grooves 36 and the gas supply holes 34 is used as the mounting surface 33 of the wafer W.

  Further, in Patent Document 4, as shown in FIG. 7A, a gas supply hole 44 and a plurality of radial grooves 45 communicating with the gas supply hole 44 are formed on the upper surface of a disc-shaped electrostatic chuck 41. And an annular groove 46 communicating with the end of each radial groove 45, and the upper surface of the electrostatic chuck 41 excluding the radial groove 45, the annular groove 46, and the gas supply hole 44 is placed on the wafer W. In addition to the surface 43, the mounting surface 43 is blasted, and an electrostatic chuck having an uneven surface as shown in FIG. 7B is disclosed on the mounting surface 43.

  In Patent Documents 5, 6, 7, and 8, as shown in FIG. 8, a plurality of minute convex portions 52 are scattered on the upper surface of a disc-shaped electrostatic chuck 51, and an annular convex portion is formed on the periphery of the upper surface. 57, and the top surfaces of the minute convex portion 52 and the annular convex portion 57 serve as a mounting surface 53 for the wafer W, and a plurality of gas supply holes 54 are provided on the upper surface of the electrostatic chuck 51. An electrostatic chuck into which a helium gas is introduced is disclosed.

Further, Patent Document 9 discloses an electrostatic chuck in which an annular convex shape is formed at the peripheral portion of the mounting surface on which the wafer W is placed, and a concave surface is formed at the central portion.
Japanese Patent No. 2626618 JP-A-6-112302 JP-A-2-119131 Japanese Patent Laid-Open No. 10-56054 Japanese Patent Laid-Open No. 7-153825 JP-A-9-213777 Japanese Patent Laid-Open No. 7-18438 JP-A-8-55905 JP 2002-261157 A

  However, when the electrostatic chuck disclosed in Patent Documents 1 to 9 is used and the space formed by the wafer W and the mounting surface is filled with helium gas or the like from the gas inlet, the outer peripheral portion of the mounting surface and the wafer As a result, the flow rate of gas leaking from the periphery of W is partially different, and the amount of heat transfer by the gas filled between the mounting surface and the wafer W is different, resulting in a temperature difference on the surface of the wafer W. There was a risk of increasing.

  Further, in the electrostatic chuck 31 having the mounting surface shown in FIG. 6, the area of the mounting surface 33 surrounded by the two adjacent radial grooves 35 and the return groove 36 is larger at the peripheral portion than at the center portion. . Therefore, the amount of heat transferred from the mounting surface 33 to the wafer W is higher at the peripheral portion than at the central portion, and the temperature of the peripheral portion of the wafer W is higher than that at the central portion. Accordingly, the electrostatic chuck 31 having the mounting surface shown in FIG. 6 has a problem that the in-plane temperature difference of the wafer W is large and the thermal uniformity is impaired.

  Further, the electrostatic chuck described in Patent Document 3 has a problem that when the pressure of the introduced gas is increased to several hundred Pa or more, the shape of the mounting surface appears in the temperature distribution and the temperature difference on the wafer surface increases. . Further, since the adsorption force is too high, residual adsorption occurs when the applied voltage is turned off, and the detachment response of the object to be held is deteriorated. As a result, there is a problem that throughput is reduced and productivity is lowered.

  Further, the electrostatic chuck described in Patent Document 8 causes residual adsorption when the applied voltage is turned off, the separation response of the object to be held deteriorates, the throughput decreases, and the productivity decreases. In addition to the problem of property, there is a problem that the defect rate is further increased. This is because the surface roughness of the electrostatic chuck is uniform and small, so the temperature uniformity is high, but the wafer is warped due to the temperature rise, so gas leaks from a minute gap near the outer edge of the substrate. This is because it generates and adversely affects the uniformity and reproducibility of the plasma processing.

  Further, the electrostatic chuck 41 shown in FIG. 7 has a problem that the in-plane temperature difference of the wafer W is large as in the electrostatic chuck of FIG.

  Thus, in the conventional electrostatic chuck, what is excellent in all the characteristics of thermal uniformity, adsorption power, and detachment response has not been obtained. As a result, the conventional electrostatic chuck has a problem that throughput is lowered and a defect rate is increased in a semiconductor manufacturing process.

  Accordingly, an object of the present invention is to provide an electrostatic chuck with little separation response and gas leak while maintaining the thermal uniformity and high adsorption force of the substrate, and a processing apparatus using the electrostatic chuck.

  As a result of intensive studies in view of the above problems, the present inventors have obtained the following findings.

  A static protrusion comprising an annular convex portion formed on the periphery of the mounting surface of the plate-shaped ceramic pair, an electrostatic adsorption electrode for adsorbing an object to be held, and a through-hole penetrating the plate-shaped ceramic body. In the electric chuck, a large amount of gas leaks from between the upper surface of the annular convex portion and the object to be held that is in contact with the upper surface of the annular convex portion, and much heat is released. On the other hand, in the portion where the arithmetic average roughness is small, there is less gas leakage than in the portion where the arithmetic average roughness is large, and the amount of heat released therewith is small. Therefore, the amount of heat transfer by the gas filled between the annular convex part, the mounting surface and the object to be held is different in each part, and the object to be heated, for example, a semiconductor wafer or a glass for liquid crystal The temperature difference in the surface of the substrate or the like becomes large. Accordingly, many defective products are generated in the object to be held subjected to the film formation process and the etching process. Therefore, if the roughness of the upper surface of the annular convex portion is made uniform by eliminating the difference in the arithmetic average roughness Ra of the annular convex portion, the upper surface of the annular convex portion and the upper surface of the annular convex portion The amount of gas leaking from between the objects to be held arranged so as to be in contact with each other can be made uniform over the entire surface of the annular convex portion, thereby improving the heat uniformity. Thereby, the semiconductor wafer or the like can be uniformly formed or etched. Further, if the difference in arithmetic mean roughness Ra of the upper surface of the annular convex portion is made as small as possible, the amount of gas leakage can be reduced, and the holding force of the object to be held can be kept high. Therefore, the present inventors have completed the present invention based on the above findings.

Therefore, in the present invention, one main surface is a mounting surface on which the object is to be held, and the other main surface or the inside is provided with an electrode for electrostatic attraction, and is provided at the outer peripheral end of the mounting surface. An electrostatic chuck comprising a plate-like ceramic body having an annular convex portion that comes into contact with the object to be held and a through hole provided inside the annular convex portion, wherein the annular convex portion is held. When the maximum value of the arithmetic average roughness Ra of the surface in contact with the object is Ra (max) and the minimum value is Ra (min),
{Ra (max) −Ra (min)} / Ra (max) is 0.2 or less.

  Further, according to the present invention, in the electrostatic chuck, an annular concave portion may be provided inside the annular convex portion.

Here, the arithmetic average roughness Ra means that a portion of the measurement length is extracted from the roughness curve in the direction of the average line, the x-axis is taken in the direction of the average line of the extracted portion, and the y-axis is taken in the direction of the vertical magnification. And the roughness curve is expressed as y = f (x),
Ra = 1 / L × ∫ ₀ ^L | f (x) | dx
Is a value expressed by μm (micrometer). More specifically, the Ra measurement method conforms to JIS B0601-1994. When the value of Ra is 0.02 μm or less, the cutoff value (λc) is 0.08 mm and the evaluation length (Ln) is 0.4 mm. When Ra exceeds 0.02 μm and is 0.1 μm or less, λc is 0.25 mm and Ln is 1.25 mm. When Ra exceeds 0.1 μm and is 2 μm or less, λc is 0.8 mm and Ln is 4 mm. When Ra exceeds 2 μm and is 10 μm or less, λc is 2.5 mm and Ln is 12.5 mm. Further, when Ra exceeds 10 μm and is 80 μm or less, λc is 8 mm and Ln is 40 mm.

  Furthermore, the electrostatic chuck according to the present invention has a smooth concave surface inside the annular concave portion at the center of the mounting surface in the above configuration, and contacts the object to be held of the annular convex portion. The surface to be protruded is higher than the concave surface.

  Furthermore, the electrostatic chuck according to the present invention is characterized in that, in the above configuration, the arithmetic average roughness Ra decreases toward the center of the concave surface.

  Furthermore, the electrostatic chuck according to the present invention is characterized in that, in the above configuration, the electrostatic chucking electrode is provided to face the smooth concave surface and the annular concave portion.

  Moreover, the electrostatic chuck according to the present invention is characterized in that, in the above configuration, the arithmetic average roughness Ra of the annular convex portion is 0.5 to 1.2 μm.

  The electrostatic chuck according to the present invention is characterized in that, in the above configuration, a heating element sheet is provided on the other main surface side of the electrostatic chuck.

  The electrostatic chuck according to the present invention is characterized in that, in the above configuration, a cooling member is provided on the lower surface side of the heating element sheet.

  Moreover, the electrostatic chuck according to the present invention is characterized in that, in the above configuration, the electrostatic chuck, the heating element sheet, and the cooling member are bonded together in this order with an organic adhesive.

The electrostatic chuck according to the present invention is characterized in that, in the above configuration, the plate-like ceramic body has a volume resistivity value of 10 ⁸ to 10 ¹² Ω · cm at 40 ° C.

  The electrostatic chuck according to the present invention is characterized in that, in the above configuration, the plate-like ceramic body is mainly composed of alumina or aluminum nitride.

  The electrostatic chuck according to the present invention is characterized in that, in the above configuration, the plate-like ceramic body contains alumina as a main component and a group 4 element compound as a trace component.

Further, in the wafer processing method according to the present invention, one main surface is a mounting surface on which a wafer is placed, and the other main surface or an electrode for electrostatic adsorption is provided on the outer peripheral end of the mounting surface. An electrostatic chuck comprising a plate-shaped ceramic body provided with an annular convex portion that comes into contact with the wafer and a through hole provided inside the annular convex portion, wherein the annular convex portion When the maximum value of the arithmetic average roughness Ra of the surface in contact with the wafer is Ra (max) and the minimum value is Ra (min),
A wafer is placed on the mounting surface of the electrostatic chuck whose {Ra (max) -Ra (min)} / Ra (max) is 0.2 or less, and the electrostatic chucking electrode provided on the electrostatic chuck is used. A process of adsorbing the wafer, a process of supplying a gas to the through-hole, a process of forming a semiconductor thin film on the wafer, and an etching process while releasing the gas at a constant flow rate from between the annular projection and the wafer. And a step of performing at least one of a resist film forming process.

Further, in the wafer processing method according to the present invention, one main surface is a mounting surface on which a wafer is placed, and the other main surface or an electrode for electrostatic adsorption is provided on the outer peripheral end of the mounting surface. An electrostatic chuck comprising a plate-shaped ceramic body provided with an annular convex portion that comes into contact with the wafer and a through hole provided inside the annular convex portion, wherein the annular convex portion When the maximum value of the arithmetic average roughness Ra of the surface in contact with the wafer is Ra (max) and the minimum value is Ra (min),
An electrostatic chuck having {Ra (max) −Ra (min)} / Ra (max) of 0.2 or less, a heating element sheet on the other main surface side of the electrostatic chuck, and further the heating element sheet A cooling member is provided on the lower surface side of the wafer, and a wafer is placed on a mounting surface of a wafer holding member in which the electrostatic chuck, the heating element sheet, and the cooling member are bonded together in this order with an organic adhesive. A step of adsorbing the wafer by the electrostatic adsorption electrode provided on the electric chuck, a step of supplying a gas to the through-hole, and discharging the gas from between the annular convex portion and the wafer at a constant flow rate. And a step of performing at least one of a semiconductor thin film forming process, an etching process, and a resist film forming process on the wafer.

  As described above, according to the present invention, one main surface is a mounting surface on which an object is placed, and the other main surface or the inside is provided with an electrode for electrostatic attraction, and the outer peripheral end of the mounting surface described above An electrostatic chuck comprising a plate-like ceramic body having an annular convex portion that is in contact with the object to be held and a through-hole provided inside the annular convex portion, the annular convex portion {Ra (max) -Ra (min)} / Ra where the maximum value of the arithmetic average roughness Ra of the surface in contact with the object to be held is Ra (max) and the minimum value is Ra (min). By setting (max) to 0.2 or less, the temperature difference in the surface of the wafer W, which is the object to be held, is reduced, the wafer W separation time is reduced, the amount of gas leak is small, and the electrostatic chuck has a large attractive force. And a wafer holding member. In addition, since the amount of gas leaked between the mounting surface and the wafer W is small, a wafer holding member that can be used in various film forming processes, etching processes, and the like can be provided.

  Further, according to the present invention, in the electrostatic chuck, it is easy to supply a gas to the back surface of the wafer W by providing an annular concave portion inside the annular convex portion.

  Furthermore, the center of the mounting surface has a gas filling surface that becomes a smooth concave surface from the annular recess, and when the top surface of the annular projection protrudes from the gas filling surface, the wafer W is removed from the mounting surface. At the time of detachment, the stress due to the warp of the wafer W acts and the wafer W can be easily detached from the mounting surface.

  Further, in the above configuration, the center of the placement surface has a smooth concave surface inside the annular recess, and a surface of the annular projection that contacts the object to be held projects higher than the concave surface. As a result, the concave surface can be filled with gas, and the wafer W can come into contact with the annular convex portion to suppress the amount of gas leakage.

  Further, in the electrostatic chuck according to the present invention, in the above configuration, when the arithmetic average roughness Ra decreases toward the center of the concave surface, the gas can smoothly flow from the annular concave portion toward the center of the concave surface.

  Furthermore, in the electrostatic chuck according to the present invention, in the above configuration, when the electrode for electrostatic attraction is provided to face the smooth concave surface and the annular concave portion, the annular convex portion and the wafer W Can be adsorbed with an appropriate force, and a desired amount of gas can flow from the gap between the annular convex portion and the wafer W.

  In the electrostatic chuck according to the present invention, in the above configuration, when the arithmetic average roughness Ra of the annular convex portion is 0.5 to 1.2 μm, the gas flowing out from the gap between the annular convex portion and the wafer W The amount can be reduced.

  The electrostatic chuck according to the present invention can heat the wafer W to a desired temperature and include the heating element sheet on the other main surface side of the electrostatic chuck. The in-plane temperature difference can be made extremely small.

  Further, in the electrostatic chuck according to the present invention, in the above configuration, when the cooling member is provided on the lower surface side of the heating element sheet, the wafer W can be heated and the wafer W can be cooled. The in-plane temperature of W can be changed rapidly.

  In the electrostatic chuck according to the present invention, in the above-described configuration, the electrostatic chuck, the heating element sheet, and the cooling member are bonded together in this order with an organic adhesive to rapidly heat or cool the wafer W. In addition, the bonded surface is less likely to peel off even when a sudden temperature change occurs.

In the electrostatic chuck according to the present invention, in the above configuration, when the volume specific resistance value at 40 ° C. of the plate-like ceramic body is 10 ⁸ to 10 ¹² Ω · cm, the wafer W is placed on the mounting surface. It can be adsorbed firmly.

  In the electrostatic chuck according to the present invention, in the above configuration, when the plate-shaped ceramic body is mainly composed of alumina or aluminum nitride, the mounting surface is corroded even if the mounting surface is exposed to a plasma atmosphere. There is no possibility that the surface roughness of the mounting surface is changed, and a wafer holding member having excellent durability can be provided.

  Further, in the electrostatic chuck according to the present invention, in the above configuration, the plate-like ceramic body contains alumina as a main component, and a group 4 element compound as a trace component can reduce the volume resistivity of alumina. At the same time, the wafer W can be firmly adsorbed to the mounting surface.

  Further, in the wafer processing method according to the present invention, one main surface is a mounting surface on which a wafer is placed, and the other main surface or an electrode for electrostatic adsorption is provided on the outer peripheral end of the mounting surface. An electrostatic chuck comprising a plate-shaped ceramic body provided with an annular convex portion that comes into contact with the wafer and a through hole provided inside the annular convex portion, wherein the annular convex portion {Ra (max) −Ra (min)} / Ra (max) is 0 when the maximum value of the arithmetic average roughness Ra of the surface in contact with the wafer is Ra (max) and the minimum value is Ra (min). A step of placing a wafer on a mounting surface of the electrostatic chuck that is less than or equal to 2 and sucking the wafer by an electrostatic chucking electrode provided on the electrostatic chuck; and a step of supplying a gas to the through hole; The gas is released at a constant flow rate between the annular projection and the wafer. However, since the surface temperature of the wafer W can be made uniform by providing the wafer with a process of performing at least one of a semiconductor thin film deposition process, an etching process, and a resist film formation process on the wafer, Even if the film forming process, the etching process, and the resist film forming process are performed, uniform processing can be performed over the entire surface of the wafer W.

  Further, in the wafer processing method according to the present invention, one main surface is a mounting surface on which a wafer is placed, and the other main surface or an electrode for electrostatic adsorption is provided on the outer peripheral end of the mounting surface. An electrostatic chuck comprising a plate-shaped ceramic body provided with an annular convex portion that comes into contact with the wafer and a through hole provided inside the annular convex portion, wherein the annular convex portion {Ra (max) −Ra (min)} / Ra (max) is 0 when the maximum value of the arithmetic average roughness Ra of the surface in contact with the wafer is Ra (max) and the minimum value is Ra (min). 2 or less, a heating element sheet on the other main surface side of the electrostatic chuck, a cooling member on the lower surface side of the heating element sheet, the electrostatic chuck, and the heating element The body sheet and the cooling member are organically bonded in this order. Placing the wafer on the mounting surface of the wafer holding member bonded in step, sucking the wafer by the electrostatic chucking electrode provided on the electrostatic chuck, supplying gas to the through hole, and A step of performing at least one of a semiconductor thin film forming process, an etching process, and a resist film forming process on the wafer while discharging the gas from the annular convex portion and the wafer at a constant flow rate. Since W can be heated to a desired temperature or cooled, and the temperature difference in the wafer W surface can be reduced, uniform processing can be performed over the entire surface of the wafer W.

  In the electrostatic chuck 1 according to the present embodiment, a plate-like ceramic body 2 having one main surface on which the object to be held is placed and the other main surface or the electrode 6 for electrostatic attraction inside. Have. Further, the plate-like ceramic body 2 is provided with an annular recess 4 away from the outer peripheral end, whereby the outer side of the annular recess 4 is an annular projection 3a. Further, a smooth concave surface 3b (smooth concave surface is used as a gas filling surface) is formed inside the annular concave portion 4, the annular convex portion 3a protrudes higher than the concave surface 3b, and the annular convex portion 3a. A through hole 5 (the through hole 5 is used as a gas supply hole) is provided further inside. In the electrostatic chuck 1, when the maximum value of the arithmetic average roughness Ra of the surface of the annular convex portion 3a in contact with the object to be held is Ra (max) and the minimum value is Ra (min), { Ra (max) -Ra (min)} / Ra (max) is 0.2 or less. An electrostatic chuck according to an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1A is a cross-sectional view showing an example of the electrostatic chuck 1 of the present invention, and FIG. 1B is an enlarged cross-sectional view of a portion A in FIG. FIG. 2 is a top view of FIG.

  This electrostatic chuck 1 has one main surface of a plate-like ceramic body 2 as a mounting surface 3 on which a wafer W to be held is placed, and an electrostatic chucking electrode 6 on the other main surface or inside. An annular convex portion 3a is provided on the periphery of the mounting surface 3, a gas filling surface 3b is provided inside the annular concave portion 4, and a through hole 5 communicating with the gas filling surface 3b is provided. If necessary, the gas filling surface 3b can be provided with a cylindrical or prismatic convex portion 3c to hold the wafer W.

  Then, the electrostatic chucking electrode 6 is provided on the other main surface or inside of the plate-shaped ceramic body 2, and the power feeding terminal 8 is connected to the electrostatic chucking electrode 6. The electrostatic attraction electrode 6 may be monopolar or hyperbolic. Moreover, you may divide | segment into 3 or more.

  Reference numeral 10 denotes a temperature measuring element for measuring the temperature of the electrostatic chuck 1.

  The plate-like ceramic body 2 includes a plurality of lift pin holes 7, and lift pins (not shown) can move up and down in the lift pin holes 7.

  The wafer W placed on the lift pins protruding from the lift pin holes 7 can be placed on the placement surface 3 as the lift pins descend. The wafer W, which is an object to be held, is held by the mounting surface 3 including the annular convex portion 3a and the gas filling surface 3b. Then, a DC voltage is applied to the electrostatic attraction electrode 6, and the wafer can be firmly adsorbed to the mounting surface 3.

  Further, a gas such as helium gas or argon gas is supplied from the through-hole 5 penetrating the plate-shaped ceramic body at the same time as the wafer W is firmly adsorbed, and the wafer W, the annular protrusion 3a, the annular recess 4 and the gas filling surface 3b The space formed by is filled with gas. The annular protrusion 3a is in surface contact with the peripheral edge of the wafer W on the lower surface thereof, thereby restricting gas leakage. Then, gas can be supplied to the annular recess 4 and the gas filling surface 3b surrounded by the annular projection 3a. The gas is supplied from the through-hole 5, spreads uniformly in the annular recess 4, and is further filled in the gas filling surface 3b that forms a minute gap with the wafer W. In addition, a small amount of gas flows out from the contact interface between the annular protrusion 3a and the wafer W. Heat is received from the annular recess 4 and the gas filling surface 3b by using a gas as a medium, and this heat is transmitted to the back surface of the wafer W, so that the temperature in the wafer W surface is made more uniform. Can supply a uniform film on the processed surface of the wafer W, and supplying an etching gas can perform uniform fine processing on the processed surface of the wafer W. Yes.

  FIG. 3A is a cross-sectional view showing another example of the electrostatic chuck 1 of the present invention, and FIG. 3B is an enlarged cross-sectional view of a portion A in FIG. FIG. 4 is a top view of FIG.

  This electrostatic chuck 1 has one main surface of a plate-like ceramic body 2 as a mounting surface 3 on which a wafer W to be held is placed, and an electrostatic chucking electrode 6 on the other main surface or inside. An annular convex portion 3 a is provided on the periphery of the mounting surface 3, an annular concave portion 4 is provided on the inner side thereof, a gas filling surface 3 b is provided on the inner side of the annular concave portion 4, and a through hole 5 communicating with the annular concave portion 4 is provided.

  Then, the electrostatic chucking electrode 6 is provided on the other main surface or inside of the plate-shaped ceramic body 2, and the power feeding terminal 8 is connected to the electrostatic chucking electrode 6. The electrostatic attraction electrode 6 may be monopolar or hyperbolic. Moreover, you may divide | segment into 3 or more.

  In the electrostatic chuck 1 of the present invention, the annular recess 4 and the through hole 5 communicate with each other, and the difference between the maximum value Ra (max) and the minimum value Ra (min) of the arithmetic average roughness Ra of the top surface of the annular protrusion 3a. The ratio [= {Ra (max) −Ra (min)} / Ra (max)] is 0.2 or less. When the ratio exceeds 0.2, the variation in the arithmetic average roughness of the annular convex portion 3a increases, and the amount of gas leaking from the contact surface between the annular convex portion 3a and the wafer W differs in each part of the annular convex portion 3a. In the portion of the convex portion 3a where the amount of leaking gas is large, the temperature of the surface of the wafer W is lowered. On the other hand, in the vicinity of the small amount of gas leaking out of the annular convex portion 3a, the temperature of the wafer W surface relatively increases, the temperature difference in the wafer W surface increases, and the temperature uniformity decreases. . It is necessary that the amount of gas flowing out from the contact interface where the annular projection 3a and the wafer W come into contact is always uniform. In particular, when the gas pressure of the gas supplied from the gas supply hole 5 to a minute gap formed by the annular recess 4 surrounded by the annular projection 3a, the gas filling surface 3b, and the wafer W exceeds 3 kPa, the annular projection 3a, the amount of gas leaking from the gap between the annular protrusion 3a and the wafer W is relatively large, and the amount of gas leaking from the gap varies greatly due to the difference in the arithmetic average roughness Ra of the annular protrusion 3a. It is. Moreover, it is easy to control the gas leakage when the width of the annular convex portion 3a is 1 to 10 mm. More preferably, this width is 1 to 3 mm.

  Regarding the arithmetic average roughness Ra, at least 6 points of the annular convex portion 3a are measured at substantially equal intervals, and the ratio can be calculated from the maximum value and the minimum value.

  The top surface 3a of the annular convex portion 3a is higher than the gas filling surface 3b formed inside the annular concave portion 4, and a smooth concave surface is formed from the annular convex 3a to the center of the gas filling surface 3b. It is preferable. The wafer W placed on the placement surface 3 is placed on the gas filling surface 3b while being in contact with the annular projection 3a, and the wafer W can be firmly adsorbed by the electrostatic adsorption force. If the top surface 3a of the annular convex portion 3a is higher than the gas filling surface 3b, the annular convex portion 3a and the lower surface of the peripheral edge of the wafer W can reliably contact each other, and gas leakage can be effectively suppressed. Further, when a smooth concave surface is formed from the annular convex portion 3a to the center of the gas filling surface 3b, the gas supplied from the annular concave portion 4 easily flows to the gas filling surface 3b. Can be reduced. Further, in the state where the wafer W is attracted, the surface of the wafer W is slightly deformed into a concave shape, and when the voltage of the electrostatic attraction electrode 6 is cut off and the wafer W is separated from the mounting surface 3, the wafer W This is because even if the residual adsorption force remains, a force that separates the wafer W from the mounting surface 3 acts due to a slight warping force of the wafer W, and the wafer W can be easily detached from the mounting surface 3.

  The arithmetic average roughness Ra of the gas filling surface 3b is preferably large at the periphery and small at the center. This is because the gas can flow smoothly from the annular recess 4 to the gas filling surface 3b by increasing the arithmetic average roughness Ra around the gas filling surface 3b. Specifically, the arithmetic average roughness Ra of the periphery of the gas filling surface 3b is preferably 0.5 to 1.2 μm. More preferably, it is 0.7-0.9 micrometer. Moreover, it is preferable that the arithmetic mean roughness of the center part of the gas filling surface 3b is smaller than the arithmetic mean roughness Ra of the periphery of the gas filling surface 3b. By setting the arithmetic average roughness Ra as described above, it is possible to appropriately fill the gap between the wafer W and the mounting surface 3, and the wafer W is deformed into a concave surface. When the voltage applied to the electrode is cut off, the wafer W is warped and the separation characteristics are improved.

  The electrostatic chucking electrode 6 extends from near the center of the plate-like ceramic body 2 to below the annular recess 4 (near the periphery of the periphery of the plate-like ceramic body 2), and the arithmetic average roughness of the annular projection. Ra is preferably 0.5 to 1.2 μm, and the average height (h) of the annular protrusion 3a is preferably higher than the average height of the gas filling surface 3b. When the outer diameter of the wafer W is 300 mm or more, the average height (h) of the annular convex portion 3a is higher than the height of the central portion of the gas filling surface 3b, and the difference is 8 to 100 μm. Preferably there is. More preferably, this difference is 10-20 μm. This is because if the electrostatic attraction electrode 6 extends to the lower side of the annular recess 4, the electrostatic attraction force at the annular projection 3a increases. Further, if the arithmetic average roughness Ra of the annular convex portion 3a is 0.5 to 1.2 μm, the leakage of the filling gas can be appropriately suppressed. When the electrostatic attraction electrode 6 extends below the annular convex portion 3a, the plasma atmosphere formed above the wafer exposed from the end face of the plate-like ceramic body and the electrostatic attraction electrode 6 There is a risk that insulation may not be removed. Further, even if the electrostatic chucking electrode 6 is not exposed from the end face of the plate-like ceramic body, the distance from the end face is reduced, and the withstand voltage between the plasma atmosphere and the suction electrode 6 may be reduced. Therefore, it is preferable that the electrostatic attraction electrode 6 extends to the lower part of the peripheral edge of the annular recess 4. This is particularly noticeable when the electrostatic chucking electrode 6 is formed on the lower surface of the plate-like ceramic body. In order to form and bury the electrostatic attraction electrode 6 below the annular recess 4 and the annular projection 3a, it is necessary to manage the shrinkage accuracy of the ceramic sintered body in detail. Further, it is preferable to form the electrostatic attraction electrode 6 on the lower surface of the plate-like ceramic body 2. This is because the electrostatic chucking electrode can be installed with high positional accuracy. When the electrostatic attraction electrode 6 extends below the annular convex portion, it is exposed from the end surface of the plate-like ceramic body and between the plasma atmosphere formed above the wafer and the electrostatic attraction electrode 6. There is a risk that insulation cannot be removed. Further, even if the electrostatic chucking electrode 6 is not exposed from the end face of the plate-like ceramic body, the distance from the end face is reduced, and the withstand voltage between the plasma atmosphere and the suction electrode 6 may be reduced. Therefore, it is preferable that the electrostatic attraction electrode 6 extends to the lower part of the peripheral edge of the annular recess 4. This is particularly noticeable when the electrostatic chucking electrode 6 is formed on the lower surface of the plate-like ceramic body. Further, the average height of the gas filling surface 3b can be obtained by an average value of the heights of four points divided into five equal parts in the maximum radial direction of the gas filling surface 3b.

  Further, it is preferable that a heating element sheet 21 is provided on the other main surface side of the electrostatic chuck 1. As shown in FIG. 5, the heating element sheet 21 is manufactured by covering the resistance heating element 22 with an insulating sheet. The resistance heating element 22 is connected to a power supply terminal 23. The resistance heating element 22 can generate heat by supplying power from the power supply terminal 23. The wafer W can be heated to a desired temperature by the resistance heating element via the electrostatic chuck 1. In particular, when helium is used as the gas and the gas pressure is set to 300 Pa or more, heat from the heating element sheet 21 is transmitted to the mounting surface 3, and heat can be efficiently transmitted from the mounting surface 3 to the wafer W. Thereby, the temperature difference in the wafer W surface can be reduced.

  Moreover, it is preferable to provide the cooling member 24 on the lower surface side of the heating element sheet 21. The cooling member 24 is formed with a flow path 29 through which a cooling medium flows, so that heat from the heating element sheet 21 and the mounting surface 3 can be taken and discharged out of the system. When the cooling member 24 is provided in this way, it is preferable because the placement surface 3 can be set to a desired temperature. By adjusting the temperature of the cooling medium and the temperature of the heating element sheet 21, it can be set to a desired temperature, particularly a temperature lower than room temperature. And since the mounting surface 3 is filled with the gas by the annular convex part 3a, the temperature difference in the wafer W surface can be reduced, which is preferable. The material of the cooling member 24 is preferably a metal having a large thermal conductivity, and it is preferable to use Al, an Al alloy, an Al—Cu composite material, or a composite member of SiC, AlN, and a metal.

  The electrostatic chuck 1, the heating element sheet 21, and the cooling member 24 are preferably bonded together with organic adhesive layers 26 and 28 in this order. The organic adhesive layers 26 and 28 are formed by the difference in thermal expansion between the electrostatic chuck 1 and the heating element sheet, the difference in thermal expansion between the heating element sheet 21 and the cooling member 24, and the plate-like ceramic body and the cooling member 24. It is preferable to reduce the difference between the thermal expansion and the thermal expansion, and it is less likely to cause cracking or peeling on the adhesive surface even when a heat cycle of heating and cooling is applied. As the adhesive, a soft resin such as an imide resin, an epoxy resin, a silicone resin, or a phenol resin is preferable, and a silicon resin is particularly preferable.

  Although not shown in the figure, the periphery of the organic adhesive layers 26 and 28 can be covered with a Teflon (registered trademark) resin having excellent corrosion resistance to enhance the corrosion resistance against plasma or the like.

Moreover, it is preferable that the volume specific resistance value in 40 degreeC of the plate-shaped ceramic body 2 is 10 < ⁸ > -10 < ¹² > (omega | ohm) * cm, It is especially preferable that it is 10 < ⁹ > -10 < ¹¹ > (omega | ohm) * cm. If the volume resistivity is less than 10 ⁸ Ω · cm, the leakage current from the plate-like ceramic body 2 to the object to be held increases, which may cause damage to the object to be held such as a wafer. On the other hand, if the volume resistivity is larger than 10 ¹² Ω · cm, the Johnson-Rahbek adsorption force decreases, and there is a possibility that sufficient adsorption force cannot be obtained.

  The plate-like ceramic body 2 preferably contains alumina or aluminum nitride (AlN) as a main component. Alumina and AlN are resistant to corrosion by corrosive gas or plasma containing fluorine, chlorine, etc., and can suppress the generation of particles and extend the product life.

  In particular, the metal impurities contained in AlN are preferably 2% by mass or less, particularly 1% by mass or less, and more preferably 0.5% by mass or less.

Moreover, it is preferable that the said plate-shaped ceramic body 2 contains an alumina as a main component and a group 4 element compound as a trace component. This is because the volume specific resistance of the plate-like ceramic body 2 can be set to 10 ⁸ to 10 ¹² Ω · cm by including a group 4 element compound in alumina. As the group 4 element, Ti, Zr, and Hf are preferable, and oxides, carbides, and nitrides of these elements are preferable. The amount of Group 4 element oxide as the trace component is preferably 0.5% by mass to 15% by mass. More preferably, it is 3-8 mass%. If it is less than 0.5% by mass, the volume resistivity may exceed 10 ¹² Ω · cm, and if it exceeds 14% by mass, it may be less than 10 ⁸ Ω · cm.

  Such an alumina ceramic body can be obtained by using an alumina powder having an average particle size of 1 μm or less, adding a Group 4 element oxide powder, firing in a non-oxidizing atmosphere after mixing and grinding. The firing temperature is preferably 1300 ° C. or lower. When the temperature exceeds 1300 ° C., the group 4 element oxide reacts with alumina to form a composite oxide. Thereby, the ceramic body is easily cracked due to the anisotropy of the thermal expansion coefficient of the composite oxide. More preferably, it is 1200-1250 degreeC. And when the said baking is baked in a normal pressure atmosphere, in order to raise the density of a sintered compact, it is more preferable to densify so that a relative density may become 99% or more by hot-pressing.

  Alternatively, pressure sintering is preferably performed in a non-oxidizing atmosphere.

  Next, another configuration of the present invention will be described.

As the metal constituting the electrostatic chucking electrode 6 of the electrostatic chuck 1 made of alumina or aluminum nitride, W, Mo, Pt, Au, Ag, Ni, TiN, WC, W ₂ C, TiC, TiB ₂ , Ti or the like can be used, but when the electrostatic adsorption electrode 6 is formed inside the substrate having the mounting surface 3 (hereinafter abbreviated as electrode built-in), the conductivity and the firing temperature of the ceramic are high. In view of the above, the metal is preferably W, WC, or Mo. Further, when the electrostatic attraction electrode 6 is formed on the back surface of the mounting surface 3, a metal of W, Mo, Pt, Au, Ag, Ni, TiN, WC, W ₂ C, TiC, TiB ₂ , Ti Either of these may be used.

  The relative density of the electrostatic adsorption electrode 4 is preferably 90% or more, particularly 95% or more, and more preferably 97% or more. As a result, generation of large pores in the electrostatic adsorption electrode 4 can be suppressed, and as a result, the in-plane distribution of the adsorption force can be easily made uniform.

  Furthermore, the relative density of the plate-like ceramic body 2 is preferably 98% or more, particularly 99% or more, and the maximum pore diameter is preferably 2 μm or less, particularly 1 μm or less. Since the size of the pores existing on the surface is as small as less than 2 μm and the number of pores existing on the surface is small, it is easy to control the arithmetic average roughness Ra to 1.2 μm or less.

  Next, the manufacturing method of the electrostatic chuck according to the present invention will be described by taking as an example the case of manufacturing the wafer holding member 100 of FIG. 5 using alumina and an AlN sintered body as the plate-like ceramic body.

First, alumina (Al ₂ O ₃ ) powder is prepared as a starting material. The alumina powder has an average particle size of 1.2 μm or less and is preferably easily sintered alumina that can be sintered at a sintering temperature of 1300 ° C. or less. A fine titanium oxide having an average particle diameter of 1 μm or less is added to the alumina powder as a trace component. Titanium oxide preferably has a rutile structure from the viewpoint of easily controlling the volume resistivity. Then, the alumina powder and the titanium oxide powder are pulverized and mixed using a vibration mill or a ball mill to produce a slurry. An organic binder is added to the prepared slurry and mixed, and then granulated and dried by a spray drying method or the like to obtain a raw material to be a composite material.

  The raw material is filled in a mold, and a substrate is formed. When it is desired to embed the electrostatic adsorption electrode, the electrostatic adsorption electrode is formed into a green body by a printing method, and the molding substrate is stacked so as to surround the electrostatic adsorption electrode, and then press-molded again. It is possible to obtain a molded body in which the electrode for electrostatic adsorption is embedded.

  And it can sinter at 1200-1300 degreeC with a nitrogen gas atmosphere furnace. An alumina raw material having low sinterability is obtained by subjecting the sintered body obtained by the above method to a pressure and heat treatment at 2000 atm. A plate-like ceramic body made of a bonded body can be obtained.

  Next, a plate-like ceramic body made of aluminum nitride will be described as an example. An AlN powder is prepared as a starting material. With respect to this AlN powder, a powder produced by a production method using a reduction nitriding method is preferable because of its high sinterability. Moreover, in order to make the volume specific resistance of an AlN sintered compact into a desired range, it is preferable to contain 1-15 mass% of cerium oxides. In addition, the metal impurities contained in these raw materials may be contained within a range that does not affect the adsorptive power. However, in order to obtain a sintered body having excellent corrosion resistance, 2 mass of metal other than Al is used. % Or less, in particular 1% by mass or less, more preferably 0.5% by mass or less.

  In addition, since carbon affects sinterability, it is preferably 1% by mass or less, particularly 0.5% by mass or less, and more preferably 0.3% by mass or less. The oxygen content of the sintered body is preferably 3% by mass or less, particularly 2% by mass or less, and more preferably 1% by mass or less. Thereby, the sintered compact used as the plate-shaped ceramic body excellent in corrosion resistance can be obtained.

  The above-described aluminum nitride powder is formed into a desired shape provided with an electrostatic chucking electrode inside as required. The molding may be performed using a molding method such as die press, CIP, tape molding, or casting. The molded body can be calcined after removing a binder component necessary for molding.

  When producing an electrostatic chuck in which an electrostatic chucking electrode is embedded, for example, a pair of molded bodies and / or calcined bodies having a relative density difference of 5% or less is prepared, and one of them is printed by a printing method. After forming an electrode by applying a paste formed by mixing a metal compound such as Mo and Mo and / or a metal compound such as TiN, a ceramic sintered body as a main component, an organic binder, and a solvent, The electrodes for electrostatic attraction can be formed by stacking them so as to be sandwiched between the molded body and / or the calcined body. As another method, an electrode may be printed on a tape molded body and inserted between a pair of press calcined bodies after calcining.

  At this time, it is preferable that the relative density difference between the calcined press calcined body and the tape calcined body which has been molded and die-molded by a mold press is 10% or less, particularly 5% or less. Thereby, generation | occurrence | production of peeling and a crack can be suppressed effectively.

  Also, when forming the electrode for electrostatic attraction, confirm the shrinkage after firing in advance, and the electrode for electrostatic adsorption at the time of formation so that the thickness of the electrode for electrostatic attraction is 7 μm or more after sintering. It is desirable to determine the thickness. For example, although depending on the composition, concentration, viscosity, pressing pressure, etc. of the electrode forming paste, it is preferable that the thickness of the electrode for electrostatic adsorption is 10 μm or more, particularly 20 μm or more, and further 30 μm or more.

  The flatness of the molded body or calcined body to which the electrode paste for electrostatic attraction is applied is preferably 200 μm or less, particularly 100 μm or less, and more preferably 50 μm or less. Thereby, it becomes easy to control the variation of the average distance from the mounting surface to the electrode for electrostatic attraction.

  Next, although the structure which consists of a molded object which provided the electrode for electrostatic attraction inside is baked, you may remove a binder component if desired before baking. Moreover, the hot press method, a normal-pressure baking method, and gas pressure baking can be used for baking. In some cases, HIP or heat treatment may be performed.

  Firing will be described using a hot press method as an example. First, it is important to load the above structure into a carbon mold of a hot press apparatus and apply a pressure less than the strength of the structure before raising the temperature. If pressure is not applied, shrinkage and deformation will occur due to temperature rise, and if the pressure is higher than the strength of the structure, the sample will be cracked by pressurization, causing disconnection or large deformation of the electrode forming part. Thus, the disconnection and deformation can be prevented.

  Next, it is preferable to hold at a temperature lower than the firing temperature. This temperature holding step has an effect of making the temperature of the structure uniform, and the holding temperature is preferably 1300 to 1700 ° C., which is close to the shrinkage start temperature. The holding pressure is preferably set to a pressure less than the strength of the structure, particularly 0.1 to 3 MPa. Further, the temperature holding is preferably 20 minutes or longer, particularly 1 hour or longer in order to make the temperature of the structure uniform.

  After finishing the temperature holding step, the temperature rise is started again, and the pressure is set to a pressure higher than the strength of the structure in a temperature range of ± 100 ° C. from the shrinkage start temperature. This pressure allows one-dimensional contraction while correcting the deformation of the electrode, and keeps the electrode flat. In particular, the pressurization start temperature is preferably within a temperature range of ± 50 ° C. from the shrinkage start temperature. In addition, you may pressurize simultaneously with restarting temperature rising when the said temperature holding | maintenance is complete | finished.

  Here, the shrinkage start temperature indicates an intersection of a linear extrapolation line at the time of non-shrinkage and a tangential extrapolation line at the time of shrinkage in a dimensional shrinkage curve at a constant rate of temperature increase.

  And it can bake at the temperature of 1750-1900 degreeC, and can obtain the ceramic sintered compact which incorporated the electrode. This calcination is preferably maintained at the above temperature for 20 minutes or more, particularly for 1 hour or more, whereby a dense body can be stably obtained.

  Furthermore, after 90% of the contraction amount of the structure contracts, it is preferable to apply a pressure higher than the firing pressure to further correct the deformation of the electrode. Thereby, the dispersion | variation in the distance from a sintered compact surface to an electrode can be made still smaller.

  The firing pressure is preferably 0.1 MPa or more in order to achieve a relative density of 99% or more. The speed at which the pressure is applied is not particularly limited.

  Therefore, for example, 0.1 to 0.2 MPa is applied as an initial pressure, and after holding at 1600 ° C. for 1 hour, the temperature rise is resumed, a pressure of 30 MPa is applied at 1700 ° C., and firing is performed at 1850 ° C. for 2 hours. .

  When the ceramic sintered body is mainly composed of an aluminum nitride crystal phase, a metal other than Al is used in order to prevent local deformation, difference in shrinkage due to the site, or stress deformation due to non-uniform dispersion of the sintering aid. The content of is preferably 1% by mass or less.

  Next, the method for forming the mounting surface of the present invention using the plate-like ceramic body made of alumina or aluminum nitride will be described. First, a ceramic substrate having a mounting surface is processed into a planar shape by a surface grinding apparatus. And a gas hole, a mounting surface, and a gas groove are formed by grinding and drilling.

  Thereafter, when the electrostatic chucking electrode is not embedded in the plate-like ceramic body 2, the metal thin film layer is placed on the other main surface of the plate-like ceramic body 2 by plating, sputtering, vapor deposition, or the like. The electrostatic chuck 1 can be manufactured by forming an electrode for electrostatic attraction having a desired shape by etching or the like. The exposed surface of the electrostatic adsorption electrode can be covered with an insulating film such as a polyimide film to maintain insulation.

  Then, a heating element sheet is bonded to the surface on which the electrostatic adsorption electrode 6 is formed via an adhesive layer 26. The adhesive layer 26 is made of a soft resin such as an imide resin, an epoxy resin, a silicone resin, or a phenol resin. Moreover, in this, a metal and a ceramic can be mixed suitably as a powder and a bulk, and a heat conductivity can be improved. In addition, you may process a mounting surface after adhesion | attachment. The heating element sheet 21 is obtained by covering the resistance heating element 22 with an insulator, and an imide resin, an epoxy resin, a silicone resin, or a phenol resin can be used as the insulator as in the case of the adhesive layer 26.

  Similarly, the heating element sheet 21 can be attached to the plate-like ceramic body 2 in which the electrostatic adsorption electrode 6 is embedded.

  Next, after the heating element sheet 21 is bonded to the electrostatic chuck 1, the cooling member 24 is bonded and fixed to the heating element sheet 21 through the adhesive layer 28. For the adhesive layer, an imide resin, an epoxy resin, a silicone resin, or a phenol resin can be used.

  Next, the shape of the mounting surface 3 is precisely ground. It is possible to process the arithmetic average roughness of the annular protrusion 3a within a desired small range by grinding the annular protrusion 3a while rotating around the center of the plate-like ceramic body 2 by rotary grinding. it can. The arithmetic average roughness Ra of the annular convex portion 3a is 1.2 μm or less, preferably 0.5 to 1.2 μm, and the maximum roughness Ry is 2 or less. The gas-filled surface 3b is preferably processed while rotating the plate-like ceramic body 2 from the outer periphery adjacent to the annular recess 4 toward the center of the plate-like ceramic body 2. At this time, the height of the annular convex portion is preferably about 10 to 100 μm higher than the height of the center of the gas filling surface 3b. Then, the grindstone moving speed in the diameter direction of the plate-like ceramic body is made constant so that the height of the center of the gas filling surface 3b is low, and the workpiece moving speed is relatively reduced at the center of the plate-like ceramic body. Reduce the surface roughness of the processing surface at the center of the plate-shaped ceramic body, reduce the grinding wheel moving speed, reduce the surface roughness at the center of the gas filling surface 3b, and increase the surface roughness at the periphery. Can do. Moreover, the substantial grinding allowance of the center part of the gas filling surface 3b becomes large, and a concave surface can be formed.

  It is preferable to precisely process the shape of the mounting surface 3 after producing the wafer holding member 100 to which the cooling member 24 is bonded and fixed. However, if the deformation of the plate-shaped ceramic body 2 is small in the bonding step, The shape of the mounting surface 3 can also be precisely processed after the plate-like ceramic body 2 is formed individually or after the electrostatic attraction electrode 6 is formed.

  Although the manufacturing method of the wafer holding member 100 provided with the resistance heating element 6 has been described above, a wafer holding member in which only the cooling member 21 is bonded and fixed except for the heating element sheet 21 can be similarly used according to the application.

  Further, the wafer holding member 100 of the present invention is suitably used as a semiconductor manufacturing apparatus including a liquid crystal substrate. That is, in such a manufacturing process, an object to be held such as a wafer W can be fixed to the mounting surface 3 of the electrostatic chuck 1 of the present invention, and processing such as conveyance, etching, and film formation can be performed efficiently. A highly productive, low cost and highly reliable semiconductor can be realized.

As a raw material, an aluminum nitride powder having an average particle diameter of 1 μm and produced by a reduction nitriding method was used. Further, 10% by mass of carbon powder having an average particle diameter of 1 μm and CeO ₂ powder having an average particle diameter of 1 μm were added and mixed so that metals other than Al were 1% by mass or less.

  To this mixed powder, ethanol and a binder were added and mixed to produce a molding powder. This molding powder was formed into a disk having a diameter of 400 mm and a thickness of 6 mm by press molding. Moreover, it shape | molded in the shape of diameter 80mm and thickness 4mm as a sample for a measurement. An electrode was formed using a paste composed of WC, AlN, and an organic binder. A pair of disks were stacked so as to sandwich the electrode, and the pair of disks stacked in this way were pressed, and the molded body was degreased to obtain a structure. This structure was placed in an AlN pot and fired in a firing furnace. The firing was previously held at 1650 ° C. near the shrinkage start temperature for 1 hour, and then fired at 1850 ° C. for 2 hours.

  Next, the outer diameter of the sintered body of the disk was processed to a diameter of 300 mm. Moreover, the gas hole, the mounting surface, and the gas groove were formed by drilling.

  The heating element sheet was bonded to the disk with a silicon adhesive, and a cooling member made of an aluminum alloy was bonded to the heating element sheet bonded to the disk with a silicon adhesive.

  For the sample mounting surface of the present invention, after the thickness grinding is processed with a surface grinder, the rotary grinder is used to finish the entire mounting surface so that the surface roughness of the annular convex portion is Ra shown in Table 1. It was. At this time, the height of the annular convex portion was set to be about 10 μm higher than the height of the central portion of the mounting surface from the groove to the center. Thereafter, the gas-filled surface was similarly ground using a rotary grinder to produce an electrostatic chuck having the structure shown in FIG. The sample is no. 1-6.

  Moreover, about the sample of the comparative example, it obtained by grinding the mounting surface of an electrostatic chuck using a surface grinder. Further, the surface roughness was adjusted by changing the abrasive grains of the diamond grindstone to # 80, # 120, and # 320.

  These samples are set in a vacuum container, the pressure in the film formation container is reduced to 0.1 Pa, and then the wafer W is placed on the mounting surface while cooling water at 20 ° C. is passed through the cooling member. A voltage of 500 V was applied to the electrode for electrodeposition, 2.6 kPa of helium gas was supplied to the gas supply hole, and power was supplied to the resistance heating element so that the average temperature on the surface of the wafer W was 100 ° C.

The surface temperature of the wafer W was measured by 32 thermocouples attached to the surface of the wafer W. The temperature 10 minutes after the average temperature of 32 thermocouples reached 100 ° C. was measured, and the difference between the maximum temperature and the minimum temperature was defined as the temperature difference within the wafer surface. The results are shown in Table 1.

  In the example (sample Nos. 1 to 6) of the present invention in which the ratio obtained by dividing the difference between the maximum value and the minimum value of the arithmetic average roughness of the annular convex portion by the maximum value is 0.2 or less, The temperature difference was as small as 1.8 ° C. or less, and it was found that these samples exhibited excellent characteristics.

On the other hand, Sample No. Nos. 7 to 9 have large ratios of 0.25, 0.30, and 0.32, and the temperature difference in the wafer surface is as large as 2.5 ° C. or more. Therefore, it was found that the characteristics of these samples were inferior.

  In the same manner as in Example 1, the electrostatic chuck, the heating element sheet, and the cooling member were bonded. A sample in which the annular convex portion was similarly ground using a rotary grinder was No. 21 to 23.

  Sample No. About 21 and 22, it processed so that a gas filling surface might become a concave surface. And the height of the center part of a gas filling surface was low, and the difference of 5-point average height (h) of a cyclic | annular convex part was 10 micrometers.

  Sample No. For 23, the gas filling surface was flat. And the height of the center part of a gas filling surface was made low, and the difference of 5-point average height (h) of a cyclic | annular convex part was 10 micrometers.

  Sample No. 1 was prepared by processing the mounting surface using a rotary grinder so that the annular convex portion of the mounting surface and the gas filling surface were at the same height. 24.

Regarding the residual adsorption force, a 300 mm wafer W was placed on the mounting surface, 500 V (bipolar voltage 250 V) was applied in the same manner as in Example 1, this was heated to 100 ° C., and after 10 minutes, the applied voltage was reduced to 0 V. The time until the pressure of the gas supply hole suddenly decreased was measured as the separation time of the wafer W. The results are shown in Table 2.

  Sample No. No. 2 was formed in which the top surface of the annular convex portion was higher than the height of the gas filling surface and the gas filling surface was formed into a smooth concave surface. Nos. 21 and 22 were found to be preferable because the separation time was as short as 7.4 seconds or less.

  Sample No. No. 23 has a separation time of 9.5 seconds. It was slightly larger than 21 and 22.

  On the other hand, Sample No. with a flat mounting surface. For 24, the departure time was as long as 15.3 seconds.

  A plate-like ceramic body was produced in the same manner as in Example 1, a metal Ti film was formed on the lower surface of the plate-like ceramic body, and this was used as an electrode for electrostatic adsorption. The width of the annular convex portion was 1.5 mm, and an annular concave portion having a width of 1 mm was formed inside thereof. The electrostatic chucking electrode has a comb-shaped hyperbolic shape and the outer shape is circular. Then, the outer diameter circle of the electrostatic adsorption electrode is the same as the outer diameter circle of the annular recess. 31-33, 35-37. In addition, the sample having the outer diameter of the electrode for electrostatic attraction equal to the inner diameter of the annular recess is designated as Sample No. 34.

And it set to the vacuum container similarly to Example 1, and similarly heated to 100 degreeC. The temperature difference in the wafer surface after 10 minutes was measured. Further, the gas leak amount was calculated from the supply gas amount. The results are shown in Table 3.

  Electrode for electrostatic attraction extends to the lower part of the annular concave portion, and the sample No. 1 in which the arithmetic average roughness Ra of the annular convex portion is 0.5 to 1.2. 32, 33, 35, and 36 were found to be preferable because the in-plane temperature difference of the wafer was as small as less than 1 ° C. and the amount of gas leak was as small as 1.4 sccm or less.

  On the other hand, Sample No. No. 31 was not preferable because the arithmetic average roughness was too small at 0.32, and the temperature difference in the wafer W plane was as large as 1.92 ° C.

  Sample No. No. 37 was not preferable because the average value of the arithmetic average roughness of the annular convex portion was as large as 1.5 and the gas leak amount was as large as 4.5 sccm.

  Sample No. Regarding No. 34, the amount of gas leakage was as large as 3.6 sccm because the electrode for electrostatic attraction did not reach below the annular recess.

  A plate-like ceramic body was prepared by using alumina and aluminum nitride as the material of the plate-like ceramic body and adding additives having the compositions shown in Table 4 respectively.

  The volume resistivity was measured at 40 ° C. by a three-terminal method based on JIS C2141.

  And the volume specific resistance of each plate-shaped ceramic body was measured, this was set to the vacuum vessel like Example 1, and it heated at 100 degreeC. The temperature difference and gas leak amount in the wafer surface were measured.

In addition, a 1-inch square silicon wafer is placed on the mounting surface, the silicon wafer is pulled up with a voltage of 500 V applied to the electrostatic chucking electrode and heated to 100 ° C., and the maximum force when the wafer is detached is electrostatically Measured as adsorption power. The results are shown in Table 4.

Sample No. with a volume resistivity of 10 ⁸ to 10 ¹² Ω · cm. As for 42 to 52, it was found that the temperature difference in the wafer surface was as small as less than 1 ° C. and the amount of gas leak was as small as less than 3 sccm.

On the other hand, Sample No. having a volume resistivity of 2.2 × 10 ¹³ Ω · cm. For No. 41, the temperature difference in the wafer surface was also as large as 1.92 ° C., and the gas leak amount was also as large as 5 sccm.

  In addition, the plate-like ceramic body has a sample No. whose main component is alumina or aluminum nitride. As for 42 to 52, it was found that the temperature difference in the wafer surface can be reduced to less than 1 ° C. and the gas leak amount can be reduced to 2.3 sccm or less.

In particular, sample no. As in 42 to 49, a wafer holding member made of a plate-like ceramic body containing alumina as a main component and a Group 4 element compound such as TiO ₂ , ZrO ₂ , HfO ₂ , TiC, or ZrC has an electrostatic adsorption force of 28 kPa or more. Therefore, it was found that excellent characteristics were exhibited.

  Furthermore, a wafer holding member made of a plate-like ceramic body containing 3 to 8% by mass of titanium oxide or a plate-like ceramic body containing cerium oxide in aluminum nitride has a large electrostatic adsorption force of 36 kPa or more and a gas leak amount of 1.1 sccm. Since it is small as below, it turned out that it is preferable.

(A) is a schematic sectional drawing of the electrostatic chuck of this invention, (b) is a rough sectional enlarged view of the A section. FIG. 2 is a schematic top view of a mounting surface of the electrostatic chuck of the present invention shown in FIG. 1. (A) is a schematic sectional drawing of the electrostatic chuck of this invention, (b) is a rough sectional enlarged view of the A section. FIG. 4 is a schematic top view of a mounting surface of the electrostatic chuck of the present invention shown in FIG. 3. It is sectional drawing to the wafer holding member using the electrostatic chuck of this invention. It is a top view of the mounting surface of the conventional electrostatic chuck. It is a top view of the mounting surface of the conventional electrostatic chuck. It is a top view of the mounting surface of the conventional electrostatic chuck.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electrostatic chuck 2 ... Plate-shaped ceramic body 3 ... Mounting surface 3a ... Ring-shaped convex part 3b ... Gas filling surface 4 ... Ring-shaped recessed part 5 ... Gas supply hole 6 ... Electrostatic adsorption electrode 8 ... Power supply terminal 9 ... Temperature sensor recess 10 ... Temperature sensor (thermocouple)
DESCRIPTION OF SYMBOLS 21 ... Heat generating body sheet 22 ... Resistance heating element 23 ... Feeding terminal 24 ... Cooling member 26 ... Adhesive layer 28 ... Adhesive layer 29 ... Cooling medium channel 100 ... Wafer holding member W ... wafer

Claims (14)

One main surface is a mounting surface on which the object to be held is placed, and the other main surface or the inside is provided with an electrode for electrostatic attraction, and is in contact with the object to be held provided at the outer peripheral end of the mounting surface. An electrostatic chuck comprising a plate-like ceramic body having an annular convex portion and a through hole provided inside the annular convex portion,
When the maximum value of the arithmetic average roughness Ra of the surface of the annular convex portion in contact with the object to be held is Ra (max) and the minimum value is Ra (min),
{Ra (max) -Ra (min)} / Ra (max) is 0.2 or less, The electrostatic chuck characterized by the above-mentioned. The electrostatic chuck according to claim 1, wherein an annular recess is provided inside the annular protrusion. The center of the mounting surface has a smooth concave surface inside the annular concave portion, and the surface of the annular convex portion that contacts the object to be held protrudes higher than the concave surface. The electrostatic chuck according to claim 2. The electrostatic chuck according to claim 3, wherein the arithmetic average roughness Ra decreases toward the center of the concave surface. The electrostatic chuck according to claim 3, wherein the electrostatic chucking electrode is provided to face the smooth concave surface and the annular concave portion. The electrostatic chuck according to claim 3, wherein the arithmetic average roughness Ra of the annular convex portion is 0.5 to 1.2 μm. A wafer holding member comprising a heating element sheet on the other main surface side of the electrostatic chuck according to claim 3. The wafer holding member according to claim 7, further comprising a cooling member on a lower surface side of the heating element sheet. The wafer holding member according to claim 8, wherein the electrostatic chuck, the heating element sheet, and the cooling member are bonded together in this order with an organic adhesive. The wafer holding member according to claim 9, wherein the plate-like ceramic body has a volume resistivity value at 40 ° C. of 10 ⁸ to 10 ¹² Ω · cm. The wafer holding member according to claim 10, wherein the plate-like ceramic body contains alumina or aluminum nitride as a main component. The wafer holding member according to claim 11, wherein the plate-like ceramic body contains alumina as a main component and a group 4 element compound as a minor component. One main surface is a mounting surface on which the wafer is placed, the other main surface or an electrostatic chucking electrode is provided inside, and an annular convex portion that is provided at the outer peripheral end of the mounting surface and contacts the wafer And an electrostatic chuck comprising a plate-like ceramic body having a through hole provided inside the annular convex portion,
When the maximum value of the arithmetic average roughness Ra of the surface of the annular protrusion contacting the wafer is Ra (max) and the minimum value is Ra (min),
{Ra (max) -Ra (min)} / Ra (max) is placed on the mounting surface of the electrostatic chuck having 0.2 or less,
Adsorbing the wafer by the electrostatic chucking electrode provided on the electrostatic chuck;
Supplying gas to the through hole;
And a step of performing at least one of a semiconductor thin film forming process, an etching process, and a resist film forming process on the wafer while discharging the gas at a constant flow rate from between the annular protrusion and the wafer. . One main surface is a mounting surface on which the wafer is placed, the other main surface or an electrostatic chucking electrode is provided inside, and an annular convex portion that is provided at the outer peripheral end of the mounting surface and contacts the wafer And an electrostatic chuck comprising a plate-like ceramic body having a through hole provided inside the annular convex portion,
When the maximum value of the arithmetic average roughness Ra of the surface of the annular protrusion contacting the wafer is Ra (max) and the minimum value is Ra (min),
An electrostatic chuck having {Ra (max) −Ra (min)} / Ra (max) of 0.2 or less, a heating element sheet on the other main surface side of the electrostatic chuck, and further the heating element sheet A cooling member is provided on the lower surface side of the wafer, and the electrostatic chuck, the heating element sheet, and the cooling member are placed on the mounting surface of the wafer holding member in which the cooling member is bonded in this order with an organic adhesive,
Adsorbing the wafer by the electrostatic chucking electrode provided on the electrostatic chuck;
Supplying gas to the through hole;
And a step of performing at least one of a semiconductor thin film forming process, an etching process, and a resist film forming process on the wafer while discharging the gas at a constant flow rate from between the annular protrusion and the wafer. .

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