Shaft-mounted ceramic heater

Abstract

To provide a technique for suppressing variations in the thickness of a film formed on the surface of a silicon wafer when a film formation process such as PE-CVD film formation is performed.SOLUTION: A ceramic heater 100 includes a disk-shaped ceramic base 110, an electrode 120 (heater electrode 122 and high-frequency electrode 124) embedded in the ceramic base 110, and a cylindrical shaft 130 joined to a lower surface 111 of the ceramic base 110. An annular convex portion 152 is provided on the upper surface 111 of the ceramic base 110. A / B, which is a ratio of an outer diameter A (mm) of the upper surface 111 of the ceramic base 110 to an outer diameter B (mm) of the annular convex portion 152, is 1.2 or more.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a shaft-equipped ceramic heater that holds and heats a substrate such as a silicon wafer. [Background technology]

[0002] Patent Document 1 discloses a shaft-equipped ceramic heater with a heating element embedded inside. The ceramic heater described in Patent Document 1 has a diameter D of 350 mm of the surface (heating surface) of the ceramic base on which a substrate is placed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-093004 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors have found that when a silicon wafer with a diameter of 300 mm is placed on a ceramic substrate having a surface (heating surface) diameter D of 350 mm as described in Patent Document 1 and a film formation process such as PE-CVD (Plasma Enhanced Chemical Vapor Deposition) is performed, variations in film thickness may occur, especially in the outer periphery of the silicon wafer.

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide a technique for suppressing variations in the thickness of a film formed on the surface of a silicon wafer when a film formation process such as PE-CVD film formation is performed. [Means for solving the problem]

[0006] According to an aspect of the present invention, a ceramic substrate having a disk-shaped structure and a lower surface facing the upper surface in a vertical direction is provided. an electrode embedded in the ceramic substrate or disposed on the lower surface of the ceramic substrate; A cylindrical shaft joined to the lower surface of the ceramic base, the ceramic base includes an annular protrusion protruding above the upper surface of the ceramic base, When the outer diameter of the upper surface of the ceramic base is A (mm) and the outer diameter of the annular convex portion is B (mm), A / B≧1.2 The present invention provides a shaft-equipped ceramic heater characterized in that Effect of the Invention

[0007] As in the above configuration, by setting the ratio A / B of the outer diameter A (mm) of the upper surface of the ceramic base to the outer diameter B (mm) of the annular convex portion at 1.2 or more, the effect of rectifying the flow of gas (source gas used in film formation) especially near the outer edge of the wafer is enhanced, thereby reducing the variation in film thickness. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a top view of a ceramic heater 100. FIG. [Diagram 2] FIG. 2 is a schematic explanatory diagram of the ceramic heater 100. As shown in FIG. [Diagram 3] FIG. 3 is a schematic diagram of the electrode 120. As shown in FIG. [Figure 4] FIG. 4 is a schematic diagram illustrating the heater electrode 122. As shown in FIG. [Diagram 5] 1(a) to 1(e) are diagrams showing a flow of a method for producing the ceramic base 110. FIG. [Figure 6] 1(a) to 1(d) are diagrams showing the flow of another method for producing the ceramic base 110. FIG. [Figure 7] FIG. 7 is a table summarizing the results of Examples 1 to 4. [Figure 8] FIG. 8 is a table summarizing the results of Comparative Examples 1 to 3. [Figure 9] FIG. 9 is an explanatory diagram for explaining dimensions A to E of the ceramic heater 100. As shown in FIG. [Figure 10] FIG. 10 is a schematic diagram for explaining positions #1 to #17 at which the film thickness of the wafer 10 is measured. [Figure 11] 1A is a schematic diagram illustrating the gas flow when the ratio A / B of the outer diameter A (mm) of the upper surface 111 of the ceramic base 110 to the outer diameter B (mm) of the annular protrusion 152 is less than 1.2, and FIG. 1B is a schematic diagram illustrating the gas flow when the ratio A / B is 1.2 or more. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] <Ceramic heater 100> A ceramic heater 100 according to an embodiment of the present invention will be described with reference to Figures 1 and 2. The ceramic heater 100 according to this embodiment is used, for example, inside semiconductor manufacturing equipment to hold and heat a semiconductor wafer such as a silicon wafer (hereinafter simply referred to as wafer 10). In the following description, the up-down direction 5 is defined based on the state in which the ceramic heater 100 is installed so that it can be used (the state in Figure 2). As shown in Figure 2, the ceramic heater 100 according to this embodiment comprises a ceramic base material 110, an electrode 120, and power supply wires 140, 141.

[0010] The ceramic base 110 is a member having a circular plate shape, and the wafer 10 is placed on the ceramic base 110. The outer diameter A of the ceramic base 110 is 360 mm. The length (thickness) of the ceramic base 110 in the vertical direction 5 is preferably 5 mm or more, and particularly preferably 15 mm to 30 mm. The ceramic base 110 can be formed of a ceramic sintered body such as aluminum nitride, silicon carbide, alumina, silicon nitride, etc. In FIG. 2, the wafer 10 and the ceramic base 110 are shown separated from each other to make the drawing easier to see. As shown in FIG. 1, the upper surface 111 of the ceramic base 110 is provided with an annular convex portion 152 (hereinafter simply referred to as the annular convex portion 152) and a plurality of convex portions 156. In FIG. 2, the number of the plurality of convex portions 156 is reduced compared to FIG. 1 to make the drawing easier to see. 1, an opening 164a of a gas flow passage 164 (see FIG. 2) is provided at the center of the ceramic base 110. The diameter of the opening 164a is 5 mm. Furthermore, lift pin holes 166 are provided at three equally spaced positions on a circle with a radius of 80 mm about the center of the ceramic base 110. The diameter of the lift pin holes 166 is 5 mm.

[0011] 1 and 2, the annular protrusion 152 is an annular protrusion disposed on the upper surface 111 of the ceramic base 110 and protrudes upward from the upper surface 111. The outer diameter B of the annular protrusion 152 is 12 inches (approximately 300 mm). As shown in FIG. 2, when the wafer 10 is placed on the ceramic base 110, the top surface 152a of the annular protrusion 152 abuts against the lower surface of the wafer 10. In other words, the annular protrusion 152 is disposed at a position that overlaps with the wafer 10 in the up-down direction 5 when the wafer 10 is placed on the ceramic base 110.

[0012] A plurality of convex portions 156 are provided on the upper surface 111 of the ceramic base material 110 inside the annular convex portion 152. The plurality of convex portions 156 are arranged in a concentric manner. The shape of the top surface 156a of the plurality of convex portions 156 is circular. The positions and / or number of the convex portions 156 are appropriately set according to the application, action, and function. For example, the plurality of convex portions 156 can be arranged at the positions of the vertices when a regular polygon such as an equilateral triangle is tiled. Alternatively, the plurality of convex portions 156 can be arranged at random positions.

[0013] In this specification, the height of the annular convex portion 152 and the height of the plurality of convex portions 156 are defined as the length in the vertical direction from the upper surface 111 of the ceramic substrate 110. If the upper surface 111 of the ceramic substrate 110 is not flat and has, for example, a step, the highest position of the upper surface 111 of the ceramic substrate 110 is used as a reference and the height is defined as the length in the vertical direction from that point. In this embodiment, the height of the plurality of convex portions 156 and the height of the annular convex portion 152 are the same and can be in the range of 5 μm to 2 mm. Here, the upper surface 111 refers to the surface on which the plurality of convex portions 156 and the annular convex portion 152 are formed.

[0014] The width of the upper surface (hereinafter referred to as top surface 152a) of the annular convex portion 152 is desirably constant and can be set to 0.1 mm to 10 mm. The center line average roughness Ra of the top surface 152a of the annular convex portion 152 can be set to 1.6 μm or less. The center line average roughness Ra is the average of the absolute values ​​of deviations from the center line of the unevenness of the surface. Similarly, the center line average roughness Ra of the top surfaces 156a of the multiple convex portions 156 can be set to 1.6 μm or less. The center line average roughness Ra of the top surface 152a of the annular convex portion 152 and the top surfaces 156a of the multiple convex portions 156 is preferably 0.4 μm or less, more preferably 0.2 μm or less, and even more preferably 0.1 μm or less.

[0015] The distance between each of the plurality of protrusions 156 can be in the range of 1.5 mm to 30 mm.

[0016] As described above, the opening 164a of the gas flow passage 164 is open at approximately the center of the upper surface 111 (see FIG. 2). The gas flow passage 164 is a gas flow passage having the opening 164a, and is formed inside the ceramic base 110. In this embodiment, the gas flow passage 164 extends downward from the opening 164a. The gas flow passage 164 can be used as a flow passage for supplying gas to a space (gap) defined by the upper surface 111 of the ceramic base 110 and the lower surface of the wafer 10. For example, a heat transfer gas for heat transfer between the wafer 10 and the ceramic base 110 can be supplied. As the heat transfer gas, for example, an inert gas such as helium or argon, or nitrogen gas can be used. The heat transfer gas is supplied through the gas flow passage 164 at a pressure set within a range of 100 Pa to 40,000 Pa. Furthermore, when process gas infiltrates into the gap inside the annular protrusion 152 from the gap between the top surface 152a of the annular protrusion 152 and the lower surface of the wafer 10, the gas can be exhausted through the gas flow path 164. At this time, the differential pressure between the pressure outside the gap and the pressure inside the gap can be adjusted by adjusting the exhaust pressure. This allows the wafer 10 to be adsorbed toward the upper surface 111 of the ceramic base material 110. Furthermore, when process gas infiltrates into the gap between the upper surface of the peripheral protrusion and the lower surface of the wafer 10, the gas can be exhausted through the gas flow path 164.

[0017] 2, a heater electrode 122 and a high-frequency electrode 124 are embedded inside the ceramic base 110. The high-frequency electrode 124 is embedded above the heater electrode 122. In the following description, the heater electrode 122 and the high-frequency electrode 124 are collectively referred to as electrode 120. Furthermore, the larger of the outer diameter C1 of the heater electrode 122 and the outer diameter C2 of the high-frequency electrode 124 is referred to as the outer diameter C of the electrode 120 (see FIG. 9).

[0018] 3, the high-frequency electrode 124 has a circular shape. The outer diameter C2 of the high-frequency electrode 124 is preferably 300 mm or more. The high-frequency electrode 124 is embedded at a position 1 mm away from the upper surface 111 of the ceramic base 110 in the vertical direction 5 (to a depth of 1 mm).

[0019] As shown in FIG. 4, the heater electrode 122 is a metal mesh or foil cut into a strip shape. The outer diameter C1 of the heater electrode 122 is preferably 290 mm or more. The heater electrode 120 is not exposed from the side of the ceramic base material 110. A terminal portion 121 to be connected to a power supply line 140 (see FIG. 1) is provided at approximately the center of the heater electrode 120. The heater electrode 122 is formed of a heat-resistant metal (high melting point metal) such as a mesh or foil woven with wires of tungsten (W), molybdenum (Mo), molybdenum and / or an alloy containing tungsten. The purity of tungsten and molybdenum is preferably 99% or more. The thickness of the heater electrode 122 is 0.15 mm or less. From the viewpoint of increasing the resistance value of the heater electrode 122 and reducing the current consumption of the ceramic heater 100, it is preferable that the wire diameter be 0.1 mm or less and the thickness of the heater electrode 122 be 0.1 mm or less excluding the wire intersections. Furthermore, the width of the heater electrode 122 cut into a strip shape is preferably 2.5 mm to 20 mm, and more preferably 5 mm to 15 mm. In this embodiment, the heater electrode 122 is cut into the shape shown in Fig. 4, but the shape of the heater electrode 122 is not limited to this and can be changed as appropriate.

[0020] As shown in FIGS. 1 and 2, a shaft 130 is connected to the lower surface 113 of the ceramic base 110. The shaft 130 has a hollow cylindrical portion 131 having a substantially cylindrical shape, and flange portions 132 and 133. The flange portion 132 is provided above the cylindrical portion 131 (see FIG. 2), and the flange portion 133 is provided below the cylindrical portion 131 (see FIG. 1). The flange portions 132 and 133 have a diameter larger than that of the cylindrical portion 131. In the following description, the longitudinal direction of the cylindrical portion 131 is defined as the longitudinal direction 6 of the shaft 130. The outer diameter D of the cylindrical portion 131 is referred to as the outer diameter D of the shaft 130 (see FIG. 9). The length of the shaft 130 in the longitudinal direction 6, including the flange portions 132 and 133, is referred to as the height E of the shaft 130 (see FIG. 9). As shown in FIG. 1, when the ceramic heater 100 is in use, the longitudinal direction 6 of the shaft 130 is parallel to the up-down direction 5 .

[0021] As shown in FIG. 2, a convex portion 114 (hereinafter referred to as a joining convex portion 114) for joining to the shaft 130 is provided on the lower surface 113 of the ceramic base 110. The shape of the joining convex portion 114 is preferably the same as the shape of the upper surface of the shaft 130 to be joined, and the diameter of the joining convex portion 114 is preferably 100 mm or less. The height of the joining convex portion 114 (height from the lower surface 113) may be 0.2 mm or more, and is preferably 5 mm or more. There is no particular upper limit on the height, but considering ease of manufacture, the height of the joining convex portion 114 is preferably 20 mm or less. In addition, the lower surface 114B of the joining convex portion 114 is preferably parallel to the lower surface 113 of the ceramic base 100. The center line average roughness Ra of the lower surface 114B of the joining convex portion 114 may be 1.6 μm or less. The center line average roughness Ra of the lower surface 114B of the bonding convex portion 114 is preferably 0.4 μm or less, and more preferably 0.2 μm or less.

[0022] The upper surface of the cylindrical portion 131 is fixed to the lower surface 114B of the joining protrusion 114 of the ceramic base 110. When the joining protrusion 114 is not formed on the ceramic base 110, the upper surface of the cylindrical portion 131 or the upper surface of the flange portion 132 is joined to the lower surface 113 of the ceramic base 110. The shaft 130 may be made of a ceramic sintered body such as aluminum nitride, silicon carbide, alumina, silicon nitride, etc., like the ceramic base 110. Alternatively, in order to improve heat insulation, the shaft 130 may be made of a material having a lower thermal conductivity than the ceramic base 110.

[0023] As shown in FIG. 2, the shaft 130 has a hollow cylindrical shape, and a through hole extending in the longitudinal direction 6 (see FIG. 1) is formed inside (a region inside the inner diameter). A power feeder 140 for supplying power to the heater electrode 122 and a power feeder 141 for supplying power to the high-frequency electrode 124 are arranged in the hollow part (through hole) of the shaft 130. Note that only one power feeder 140 is shown in FIG. 2, but actually, a plurality of power feeders 140 are arranged. The upper end of the power feeder 140 is electrically connected to a terminal portion 121 (see FIG. 4) arranged in the center of the heater electrode 122. The power feeder 140 is connected to a heater power source (not shown). As a result, power is supplied to the heater electrode 122 via the power feeder 140. Similarly, power is supplied to the high-frequency electrode 124 via the power feeder 141.

[0024] 2, the second gas flow passage 168 extending in the vertical direction 5 is formed in the cylindrical portion 131 of the shaft 130. As described above, the upper end of the second gas flow passage 168 is connected to the lower end of the first gas flow passage 164.

[0025] Next, a method for manufacturing the ceramic heater 100 will be described. In the following, a case where the ceramic base 110 and the shaft 130 are made of aluminum nitride will be described as an example.

[0026] First, a method for manufacturing the ceramic base 110 will be described. For the sake of simplicity, it is assumed that only a heater electrode 122 is embedded as the electrode 120 inside the ceramic base 110. As shown in FIG. 5(a), granulated powder Q mainly composed of aluminum nitride (AlN) powder is placed in a bedded carbon mold 601 and pre-pressed with a punch 602. The granulated powder Q contains 5 wt % or less of a sintering aid (for example, Y 2 O 3 5(b), a heater electrode 122 cut into a predetermined shape is placed on the pre-pressed granulated powder Q. The heater electrode 122 is placed parallel to a surface perpendicular to the pressing direction (the bottom surface of the bed-equipped mold 601). At this time, a W pellet or a Mo pellet may be embedded at the position of the terminal 121 (see FIG. 4) of the heater electrode 122.

[0027] As shown in FIG. 5(c), granulated powder Q is further put into the bed-type mold 601 so as to cover the heater electrode 122, and pressed and molded with a punch 602. Next, as shown in FIG. 5(d), the granulated powder Q with the heater electrode 122 embedded therein is fired in a pressed state. The pressure applied during firing is preferably 1 MPa or more. Also, firing is preferably performed at a temperature of 1800° C. or more. Next, as shown in FIG. 5(e), blind holes are drilled to the heater electrode 122 in order to form the terminal 121. In addition, when a pellet is buried, blind holes may be drilled to the pellet. Furthermore, a through hole that becomes a part of the gas flow path 164 is formed. This allows the ceramic base material 110 with the gas flow path 164 formed therein to be produced. In this case, it is preferable to provide a predetermined opening in the heater electrode 122 in advance so that the heater electrode 122 is not exposed from the gas flow path 164.

[0028] The ceramic substrate 110 can also be manufactured by the following method. As shown in Fig. 6(a), a binder is added to aluminum nitride granulated powder Q, which is then CIP molded and processed into a disk shape to produce an aluminum nitride compact 610. Next, as shown in Fig. 6(b), the compact 610 is degreased to remove the binder.

[0029] As shown in FIG. 6(c), a recess 511 for embedding a heater electrode 122 is formed in a degreased molded body 610. A heater electrode 122 is placed in the recess 611 of the molded body 610, and another molded body 610 is laminated. The recess 611 may be formed in the molded body 610 in advance. Next, as shown in FIG. 6(d), the laminated molded bodies 610 sandwiching the heater electrode 122 are fired in a pressed state to produce a fired body. The pressure applied during firing is preferably 1 MPa or more. Also, firing is preferably performed at a temperature of 1800° C. or more. The steps after producing the fired body are the same as those described above, and therefore will not be described.

[0030] The upper surface 111 of the ceramic base material 110 thus formed is ground and polished. Furthermore, the upper surface 111 is sandblasted to form a plurality of convex portions 156 and annular convex portion 152 on the upper surface 111. At this time, the heights of the plurality of convex portions 156 are processed to be the same. The top surface 152a of the annular convex portion 152 is also processed to a predetermined shape. Note that sandblasting is a suitable processing method for forming the plurality of convex portions 156 and the annular convex portion 152, but other processing methods can also be used. Furthermore, a cylindrical processing can be performed on the lower surface 113 of the ceramic base material 110 to form a convex portion 114 for joining that protrudes from the lower surface 113.

[0031] Next, a method for manufacturing the shaft 130 and a method for bonding the shaft 130 and the ceramic base 110 will be described. First, granulated powder Q of aluminum nitride to which a binder is added by several wt % is molded by hydrostatic pressure (about 1 MPa) to process the molded body into a predetermined shape. At this time, a through hole that becomes the second gas flow path 168 is formed in the molded body. The outer diameter D of the shaft 130 is about 30 mm to 100 mm. The end face of the cylindrical part 131 of the shaft 130 does not need to have the flange part 133. The length of the cylindrical part 131 can be, for example, 50 mm to 500 mm. After processing the molded body into a predetermined shape, the molded body is fired in a nitrogen atmosphere. For example, the molded body is fired at a temperature of 1900° C. for 2 hours. Then, the sintered body is processed into a predetermined shape after firing to form the shaft 130. The upper surface of the cylindrical part 131 and the bonding protrusion 114 of the ceramic base 110 can be fixed by diffusion bonding at 1600° C. or higher and under a uniaxial pressure of 1 MPa or higher. In this case, the center line average roughness Ra of the lower surface 114B of the joining protrusion 114 of the ceramic base material 110 is preferably 0.4 μm or less, and more preferably 0.2 μm or less. The upper surface of the flange portion 133 and the lower surface 114B of the joining protrusion 114 can also be joined using a joining agent. As the joining agent, for example, an AlN joining material paste to which 10 wt% Y2O3 is added can be used. For example, the above-mentioned AlN joining agent paste is applied to the interface between the upper surface of the flange portion 133 and the lower surface 114B of the joining protrusion 114 to a thickness of 15 μm, and the joining can be performed by heating at a temperature of 1700° C. for 1 hour while applying a force of 5 kPa in a direction perpendicular to the upper surface 111 (the longitudinal direction 6 of the shaft 130). Alternatively, the upper surface of the cylindrical portion 131 and the lower surface 114B of the joining protrusion 114 can be fixed by screwing, brazing, or the like. EXAMPLES

[0032] The present invention will be further described below using Examples 1 to 4. However, the present invention is not limited to the Examples described below. Fig. 7 shows a table summarizing the results of Examples 1 to 4. Fig. 8 shows a table summarizing the results of Comparative Examples 1 to 3.

[0033] [Example 1] A ceramic heater 100 (see FIG. 2) according to a first embodiment will be described. In the first embodiment, 5 wt % of a sintering aid (Y 2 O 3 The ceramic substrate 110 having a thickness of 25 mm was fabricated by the above-mentioned fabrication method using aluminum nitride (AlN) to which ZnO was added as a raw material. The outer diameter A of the ceramic substrate 110 was 365 mm.

[0034] A heater electrode 122 cut to the shape shown in Fig. 4 was embedded in a position 10 mm away from the upper surface 111 of the ceramic base 110 in the vertical direction 5. The outer diameter C1 of the heater electrode 122 was 290 mm. Furthermore, a high-frequency electrode 124 having the shape shown in Fig. 3 was embedded in a position 1 mm away from the upper surface 111 of the ceramic base 110 in the vertical direction 5. The outer diameter C2 of the high-frequency electrode 124 was 300 mm.

[0035] Also, the shaft 130 was produced using aluminum nitride (AlN) without the addition of a sintering aid as a raw material, and was joined to the lower surface 113 of the ceramic base 110. The joining protrusion 114 was not formed on the ceramic base 110 of Example 1. The shaft 130 of Example 1 was provided with the flange portion 132 but not with the flange portion 133. In Example 1, the upper surface of the flange portion 132 of the shaft 130 was joined to the lower surface 113 of the ceramic base 110. The outer diameter of the flange portion 132 was 100 mm, and the thickness (length in the vertical direction 5) was 15 mm. The outer diameter D of the shaft 130 (outer diameter of the cylindrical portion 131 of the shaft 130, see FIG. 9) was 70 mm, the inner diameter was 60 mm, and the height E of the shaft 130 including the flange portion 132 (see FIG. 9) was 200 mm.

[0036] An opening 164a of a gas flow passage 164 (see FIG. 2) was provided at the center of the ceramic base 110. The diameter of the opening 164a was 5 mm. Furthermore, lift pin holes 166 were provided at three equally spaced positions on a circle with a radius of 80 mm (a virtual circle with a pitch circle diameter of 160 mm) about the center of the ceramic base 110. The diameter of the lift pin holes 166 was 5 mm.

[0037] An annular convex portion 152 was formed on the upper surface 111 of the ceramic base material 110. The outer diameter B of the annular convex portion 152 was 300 mm, the width was 2 mm, and the height was 15 μm. Furthermore, a plurality of cylindrical convex portions 156 were formed on the upper surface 111 of the ceramic base material 110. The shape of the top surface 156a of the plurality of convex portions 156 was a circle with a diameter of 3 mm. The height of the plurality of convex portions 156 was 15 μm. The plurality of convex portions 156 were arranged at the apexes of each equilateral triangle when equilateral triangles with sides of 10 mm were laid out without gaps. The center line average roughness Ra of the top surface 152a of the annular convex portion 152 and the top surface 156a of the plurality of convex portions 156 were both 0.2 μm.

[0038] As described above, in Example 1, the outer diameter A of the upper surface 111 of the ceramic base 110 was 365 mm, the outer diameter B of the annular protrusion 152 was 300 mm, and the ratio A / B was 1.22.

[0039] The ceramic heater 100 having such a shape was installed in the chamber 800, and a wafer 10 having a diameter of 300 mm was placed on the ceramic heater 100 (see FIG. 11(b)). An external power supply (not shown) was then connected to the heater electrode 122 of the ceramic heater 100. PE-CVD film formation (Plasma Enhanced Chemical Vapor Deposition) was performed on the wafer 10 in the following procedure, and the film formation distribution was evaluated.

[0040] The source gas was TEOS (tetraethoxysilane, Si(OC 2 H 5 ) 4 ) and O 2The source gas was supplied toward the wafer 10 from a shower head SH facing the wafer 10 placed on the ceramic base 110 in the up-down direction 5 (see FIG. 11(b)). The pressure (process pressure) in the chamber 800 at this time was set to 500 Pa, and the output of the external power source connected to the heater electrode 122 was adjusted so that the temperature of a thermocouple (not shown) for controlling the heater electrode embedded inside the ceramic base 110 was 350° C. In addition, a high-frequency voltage (13.56 MHz) was applied to the high-frequency electrode 124 to generate plasma.

[0041] PE-CDV film formation was performed under the above conditions, and film thickness was measured with a spectroscopic film thickness meter at 17 positions (#1 to #17) on wafer 10 shown in Fig. 10. The position indicated by #1 is the center position of wafer 10, the positions indicated by #2 to #9 are eight equally spaced positions on the circumference of a circle with a radius of 70 mm (r = 70 mm) from the center of wafer 10, and the positions indicated by #10 to #17 are eight equally spaced positions on the circumference of a circle with a radius of 140 mm (r = 140 mm) from the center of wafer 10.

[0042] 7 shows the film thickness values ​​measured at each of the positions #1 to #17. Also shown is the average film thickness measured on the circumference of a circle with a radius of 70 mm from the center of the wafer 10 (hereinafter referred to as the circle with r70 mm), and the average film thickness measured on the circumference of a circle with a radius of 140 mm from the center of the wafer 10 (hereinafter referred to as the circle with r140 mm). Also shown is the range Δd1 of film thickness in the radial direction (maximum value-minimum value of the average film thickness on each circumference), the range Δd2 of film thickness in the circumferential direction of the circle with r70 mm, and the range Δd3 of film thickness in the circumferential direction of the circle with r140 mm.

[0043] In Example 1, the range Δd1 of film thickness in the radial direction was 6.5 nm. The range Δd2 of film thickness in the circumferential direction of the circle with r 70 mm was 4.0 nm, and the range Δd3 of film thickness in the circumferential direction of the circle with r 140 mm was 5.0 nm. In Example 1, the range Δd1 of film thickness in the radial direction was 10 nm or less, and the range Δd2 of film thickness in the circumferential direction of the circle with r 70 mm and the range Δd3 of film thickness in the circumferential direction of the circle with r 140 mm were both 5.0 nm or less. The film deposition distribution evaluation for the wafer 10 was determined to be good.

[0044] [Example 2] The ceramic heater 100 of Example 2 has a similar configuration to the ceramic heater 100 of Example 1, except that the outer diameter C1 of the heater electrode 122 was 320 mm. In Example 2, the outer diameter C1 of the heater electrode 122 was larger than the outer diameter B of the annular protrusion 152 (C1>B). In Example 2, the ratio A / B of the outer diameter A of the upper surface 111 of the ceramic base 110 to the outer diameter B of the annular protrusion 152 was 1.22.

[0045] Ceramic heater 100 having such a shape was placed in chamber 800, and wafer 10 similar to that in Example 1 was placed on ceramic heater 100. Then, PE-CVD film formation was performed on wafer 10 in the same procedure as in Example 1, and the film formation distribution was evaluated.

[0046] In Example 2, the film thickness range Δd1 in the radial direction was 3.3 nm, the film thickness range Δd2 in the circumferential direction of the circle with r 70 mm was 3.0 nm, and the film thickness range Δd3 in the circumferential direction of the circle with r 140 mm was 4.0 nm. In Example 2, the film thickness range Δd1 in the radial direction was 10 nm or less. In addition, the film thickness range Δd2 in the circumferential direction of the circle with r 70 mm and the film thickness range Δd3 in the circumferential direction of the circle with r 140 mm were both 5.0 nm or less. The film deposition distribution evaluation for the wafer 10 was determined to be good.

[0047] [Example 3] The ceramic heater 100 of Example 3 has a similar configuration to the ceramic heater 100 of Example 1, except that the outer diameter C1 of the heater electrode 122 is 320 mm, and the outer diameter C2 of the high-frequency electrode 124 is 355 mm. In Example 3, the outer diameter C1 of the heater electrode 122 is larger than the outer diameter B of the annular convex portion 152 (C1>B), and the outer diameter C2 of the high-frequency electrode 124 is larger than the outer diameter B of the annular convex portion 152 (C2>B). In Example 3, the ratio A / B of the outer diameter A of the upper surface 111 of the ceramic base 110 to the outer diameter B of the annular convex portion 152 was 1.22.

[0048] Ceramic heater 100 having such a shape was placed in chamber 800, and wafer 10 similar to that in Example 1 was placed on ceramic heater 100. Then, PE-CVD film formation was performed on wafer 10 in the same procedure as in Example 1, and the film formation distribution was evaluated.

[0049] In Example 3, the film thickness range Δd1 in the radial direction was 1.8 nm, the film thickness range Δd2 in the circumferential direction of the circle with r 70 mm was 3.0 nm, and the film thickness range Δd3 in the circumferential direction of the circle with r 140 mm was 2.0 nm. In Example 3, the film thickness range Δd1 in the radial direction was 10 nm or less. In addition, the film thickness range Δd2 in the circumferential direction of the circle with r 70 mm and the film thickness range Δd3 in the circumferential direction of the circle with r 140 mm were both 5.0 nm or less. The film deposition distribution evaluation for the wafer 10 was determined to be good.

[0050] [Example 4] The ceramic heater 100 of Example 4 has a similar configuration to the ceramic heater 100 of Example 1, except that the outer diameter A of the ceramic base 110 is 500 mm, the outer diameter C1 of the heater electrode 122 is 400 mm, and the outer diameter C2 of the high-frequency electrode 124 is 355 mm. In Example 4, the outer diameter C1 of the heater electrode 122 is larger than the outer diameter B of the annular convex portion 152 (C1>B), and the outer diameter C2 of the high-frequency electrode 124 is larger than the outer diameter B of the annular convex portion 152 (C2>B). In Example 4, the ratio A / B of the outer diameter A of the upper surface 111 of the ceramic base 110 to the outer diameter B of the annular convex portion 152 was 1.67.

[0051] Ceramic heater 100 having such a shape was placed in chamber 800, and wafer 10 similar to that in Example 1 was placed on ceramic heater 100. Then, PE-CVD film formation was performed on wafer 10 in the same procedure as in Example 1, and the film formation distribution was evaluated.

[0052] In Example 4, the film thickness range Δd1 in the radial direction was 2.6 nm, the film thickness range Δd2 in the circumferential direction of the circle with r 70 mm was 2.0 nm, and the film thickness range Δd3 in the circumferential direction of the circle with r 140 mm was 3.0 nm. In Example 4, the film thickness range Δd1 in the radial direction was 10 nm or less. In addition, the film thickness range Δd2 in the circumferential direction of the circle with r 70 mm and the film thickness range Δd3 in the circumferential direction of the circle with r 140 mm were both 5.0 nm or less. The film deposition distribution evaluation for the wafer 10 was determined to be good.

[0053] [Comparative Example 1] The ceramic heater 100 of Comparative Example 1 had a similar configuration to the ceramic heater 100 of Example 1, except that the outer diameter A of the ceramic base 110 was 310 mm. In Comparative Example 1, the ratio A / B of the outer diameter A of the upper surface 111 of the ceramic base 110 to the outer diameter B of the annular protrusion 152 was 1.03.

[0054] Ceramic heater 100 having such a shape was placed in chamber 800, and wafer 10 similar to that in Example 1 was placed on ceramic heater 100. Then, PE-CVD film formation was performed on wafer 10 in the same procedure as in Example 1, and the film formation distribution was evaluated.

[0055] In Comparative Example 1, the range Δd1 of film thickness in the radial direction was 18.8 nm, the range Δd2 of film thickness in the circumferential direction of the circle with r 70 mm was 8.0 nm, and the range Δd3 of film thickness in the circumferential direction of the circle with r 140 mm was 10.0 nm. In Comparative Example 1, the range Δd1 of film thickness in the radial direction exceeded 10 nm. In addition, the range Δd2 of film thickness in the circumferential direction of the circle with r 70 mm and the range Δd3 of film thickness in the circumferential direction of the circle with r 140 mm both exceeded 5.0 nm. It was determined that the film distribution evaluation for the wafer 10 was impossible.

[0056] [Comparative Example 2] The ceramic heater 100 of Comparative Example 2 had a similar configuration to the ceramic heater 100 of Example 1, except that the outer diameter A of the ceramic base 110 was 350 mm and the outer diameter C1 of the heater electrode 122 was 320 mm. In Comparative Example 2, the ratio A / B of the outer diameter A of the upper surface 111 of the ceramic base 110 to the outer diameter B of the annular protrusion 152 was 1.17.

[0057] Ceramic heater 100 having such a shape was placed in chamber 800, and wafer 10 similar to that in Example 1 was placed on ceramic heater 100. Then, PE-CVD film formation was performed on wafer 10 in the same procedure as in Example 1, and the film formation distribution was evaluated.

[0058] In Comparative Example 2, the range Δd1 of film thickness in the radial direction was 11.8 nm, the range Δd2 of film thickness in the circumferential direction of the circle with r 70 mm was 6.0 nm, and the range Δd3 of film thickness in the circumferential direction of the circle with r 140 mm was 8.0 nm. In Comparative Example 2, the range Δd1 of film thickness in the radial direction exceeded 10 nm. In addition, the range Δd2 of film thickness in the circumferential direction of the circle with r 70 mm and the range Δd3 of film thickness in the circumferential direction of the circle with r 140 mm both exceeded 5.0 nm. It was determined that the film distribution evaluation for the wafer 10 was not possible.

[0059] [Comparative Example 3] The ceramic heater 100 of Comparative Example 3 had a similar configuration to the ceramic heater 100 of Example 1, except that the outer diameter A of the ceramic base 110 was 350 mm, the outer diameter C1 of the heater electrode 122 was 320 mm, and the outer diameter C2 of the high-frequency electrode 124 was 340 mm. In Comparative Example 1, the ratio A / B of the outer diameter A of the upper surface 111 of the ceramic base 110 to the outer diameter B of the annular convex portion 152 was 1.17.

[0060] Ceramic heater 100 having such a shape was placed in chamber 800, and wafer 10 similar to that in Example 1 was placed on ceramic heater 100. Then, PE-CVD film formation was performed on wafer 10 in the same procedure as in Example 1, and the film formation distribution was evaluated.

[0061] In Comparative Example 3, the film thickness range Δd1 in the radial direction was 11.5 nm, the film thickness range Δd2 in the circumferential direction of the circle with r 70 mm was 5.0 nm, and the film thickness range Δd3 in the circumferential direction of the circle with r 140 mm was 7.0 nm. In Comparative Example 3, the film thickness range Δd1 in the radial direction exceeded 10 nm. In addition, the film thickness range Δd2 in the circumferential direction of the circle with r 70 mm was 5.0 nm or less, but the film thickness range Δd3 in the circumferential direction of the circle with r 140 mm exceeded 5.0 nm. It was determined that the film formation distribution evaluation for the wafer 10 was impossible.

[0062] <Effects of the embodiment> In the above embodiment and Examples 1 to 4, the ceramic heater 100 includes a disk-shaped ceramic base 110, an electrode 120 (heater electrode 122 and high-frequency electrode 124) embedded in the ceramic base 110, and a cylindrical shaft 130 joined to a lower surface 111 of the ceramic base 110. An annular convex portion 152 is provided on the upper surface 111 of the ceramic base 110.

[0063] Comparing Examples 1 to 4 with Comparative Examples 1 to 3, it was found that when the ratio A / B of the outer diameter A (mm) of the upper surface 111 of the ceramic substrate 110 to the outer diameter B (mm) of the annular convex portion 152 is 1.2 or more, the radial film thickness variation and circumferential film thickness variation during PE-CVD film formation on the wafer 10 can be suppressed, enabling uniform film formation.

[0064] 11(a) and 11(b), the gas supplied from the shower head SH flows toward the exhaust hole 801 provided at the bottom of the chamber 800. According to the findings of the inventors, it is believed that the flow of the gas supplied from the shower head SH is disturbed at the outer edge of the ceramic base 110. When the ratio A / B of the outer diameter A (mm) of the upper surface 111 of the ceramic base 110 to the outer diameter B (mm) of the annular convex portion 152 is less than 1.2, it is believed that the disturbed gas flow at the outer edge of the ceramic base 110 affects the film formation on the wafer 10 and causes the film thickness to vary, as shown in FIG. 11(a). On the other hand, when the ratio A / B of the outer diameter A (mm) of the upper surface 111 of the ceramic base 110 to the outer diameter B (mm) of the annular convex portion 152 is 1.2 or more, as shown in FIG. 11(b), even if the gas flow is disturbed at the outer edge of the ceramic base 110, the gas flow is less disturbed near the outer edge of the wafer 10, and it is considered that the variation in the film thickness can be suppressed. In other words, by setting the ratio A / B of the outer diameter A (mm) of the upper surface 111 of the ceramic base 110 to the outer diameter B (mm) of the annular convex portion 152 to be 1.2 or more, it is considered that the effect of rectifying the gas flow especially near the outer edge of the wafer 10 is enhanced. This is considered to contribute to the uniformity of the film thickness. There is no particular limit to the upper limit of A / B, but it is preferable to set it to 1.67 or less due to the manufacturing constraints of the ceramic base 110 (upper limit of A is 500 mm).

[0065] Comparing Example 1 with Examples 2 and 3, it was found that the uniformity of the film thickness can be improved by making the larger outer diameter C of the outer diameter C1 of the heater electrode 122 and the outer diameter C2 of the high-frequency electrode 124 larger than the outer diameter B of the annular protrusion 152 (B>C). In particular, by making the outer diameter C1 of the heater electrode 122 larger than the outer diameter B of the annular protrusion 152, the substrate mounting area of ​​the upper surface 111 of the ceramic substrate 110 on which the wafer 10 is mounted can be made uniform in temperature. It is believed that this can improve the uniformity of the film thickness.

[0066] Comparing Examples 1 and 2 with Example 3, it was found that the uniformity of the film thickness can be further improved by setting the difference AC between the larger outer diameter C of the outer diameter C1 of the heater electrode 122 and the outer diameter C2 of the high-frequency electrode 124 and the outer diameter A of the upper surface 111 of the ceramic base 110 to less than 10 mm. In particular, when the difference A-C2 between the outer diameter C2 of the high-frequency electrode 124 and the outer diameter A of the upper surface 111 of the ceramic base 110 is set to less than 10 mm, the plasma can be uniformized. Furthermore, when the difference A-C1 between the outer diameter C1 of the heater electrode 122 and the outer diameter A of the upper surface 111 of the ceramic base 110 is set to less than 10 mm, the substrate mounting area on which the wafer 10 is mounted can be uniformly heated. It is believed that this can improve the uniformity of the film thickness.

[0067] <Modification form> The above-mentioned embodiment is merely an example and may be modified as appropriate. For example, the shape and dimensions of the ceramic base 110 are not limited to those of the above-mentioned embodiment and may be modified as appropriate. For example, when a wafer with a diameter of 12 inches (about 300 mm) is used, the outer diameter A of the upper surface 111 of the ceramic base 110 may be set to 355 mm to 420 mm, the outer diameter B of the annular protrusion 152 may be set to 290 mm to 300 mm, and the larger outer diameter C of the outer diameter C1 of the heater electrode 122 and the outer diameter C2 of the high-frequency electrode 124 may be set to 290 mm to 410 mm. In addition, when a wafer with a diameter of 8 inches (about 200 mm) is used, the outer diameter A of the upper surface 111 of the ceramic base material 110 can be set to 245 mm to 320 mm, the outer diameter B of the annular protrusion 152 can be set to 190 mm to 200 mm, and the larger outer diameter C of the outer diameter C1 of the heater electrode 122 and the outer diameter C2 of the high-frequency electrode 124 can be set to 190 mm to 310 mm. In addition, the dimensions such as the height and width of the annular protrusion 152, the shape of the top surface 152a of the annular protrusion 152, and the magnitude of the center line average roughness Ra of the top surface 152a can also be changed as appropriate. The height of the multiple protrusions 156, the shape of the top surface 156a, and the magnitude of the center line average roughness Ra of the top surface 156a can also be changed as appropriate. For example, the shape of the top surface 156a of the multiple protrusions 156 does not necessarily have to be circular, and can be an appropriate shape such as a square.

[0068] In the above embodiment, molybdenum, tungsten, or an alloy containing molybdenum and / or tungsten is used as the heater electrode 122, but the present invention is not limited to such an embodiment. For example, metals or alloys other than molybdenum and tungsten may be used.

[0069] In the above embodiment, the ceramic heater 100 includes the heater electrode 122 and the high-frequency electrode 124 embedded in the ceramic base 110, but the present invention is not limited to such an embodiment, and the heater electrode 122 and / or the high-frequency electrode 124 do not have to be embedded in the ceramic base 110 of the ceramic heater 100. For example, the heater electrode 122 or the high-frequency electrode 124 may be affixed to the back surface 113 of the ceramic base 110.

[0070] Although the present invention has been described above using the embodiment and its modified form, the technical scope of the present invention is not limited to the above description. It is obvious to those skilled in the art that various modifications or improvements can be made to the above embodiment. It is also clear from the claims that such modifications or improvements can be included in the technical scope of the present invention.

[0071] The order of execution of each process in the manufacturing method shown in the specification and drawings is not particularly specified, and may be any order unless the output of a previous process is used in a subsequent process. For convenience, even if the description uses "first," "next," etc., it does not mean that the process must be performed in that order. [Explanation of symbols]

[0072] 100 Substrate holding member 110 Ceramic substrate 122 Heater electrode 124 High Frequency Electrode 140, 141 Power line 152 Annular protrusion 156 Multiple protrusions 164 Gas flow path

Claims

1. A disk-shaped ceramic substrate having an upper surface and a lower surface facing the upper surface in the vertical direction; an electrode embedded in the ceramic substrate or disposed on the lower surface of the ceramic substrate; A cylindrical shaft joined to the lower surface of the ceramic base, the ceramic base includes an annular protrusion protruding above the upper surface of the ceramic base, When the outer diameter of the upper surface of the ceramic base is A (mm) and the outer diameter of the annular convex portion is B (mm), A / B≧1.2 1. A shaft-equipped ceramic heater comprising:

2. the electrodes are embedded in the ceramic substrate; When the outer diameter of the electrode is C (mm), C>B 2. The shaft-equipped ceramic heater according to claim 1,

3. When the outer diameter of the electrode is C (mm), A-C<10mm 2. The shaft-equipped ceramic heater according to claim 1,

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