Heating device with electrostatic adsorption function

Abstract

The present invention provides a heating device with an electrostatic adsorption function that improves the temperature distribution of a wafer. [Solution] The heating device 1 includes at least a support substrate 2, an electrostatic adsorption electrode 4 and a heating layer 5 formed on the support substrate, an insulating layer 3 containing boron nitride formed on the electrostatic adsorption electrode and the heating layer, and a power supply terminal portion 7 for supplying power to the heating layer, and has an electrostatic adsorption function. The power supply terminal portion has a structure in which there is no through hole connecting to the wafer mounting surface, and a positioning recess 9 is provided in the power supply terminal portion.

Description

[Technical Field]

[0001] The present invention relates to a heating device having an electrostatic adsorption function, and more particularly to a heating device having an electrostatic adsorption function that is suitably used in a heating process of a semiconductor wafer in a semiconductor device manufacturing process that includes a temperature rise step. [Background technology]

[0002] In recent semiconductor device manufacturing processes, heating devices with electrostatic adsorption capabilities are used to electrostatically adsorb and support wafers in processes such as molecular beam epitaxy, CVD, sputtering, etching, and ion implantation. As the process temperature increases, the material of these electrostatic adsorption heating devices has shifted from resin to ceramics (see Patent Documents 1 and 2), and in high-temperature processes above 200°C, ceramic-integrated wafer heating devices that use a ceramic thin film as a heating layer are used (see, for example, Patent Document 3).

[0003] One example of a heating device with electrostatic adsorption capabilities used in such high-temperature processes is an electrostatic chuck formed from pyrolytic boron nitride and pyrolytic carbon. This device has an integrated resistance heating type with a multilayer structure and electrostatic adsorption capabilities, in which an insulating layer made of pyrolytic boron nitride (hereinafter sometimes referred to as "PBN") is formed on a (support) substrate made of carbon or a carbon composite material by thermochemical vapor deposition (thermal CVD), a conductive layer made of pyrolytic graphite formed by thermal CVD is processed into a heater pattern and bonded, and the heater pattern is further covered with a dense layered protective film such as pyrolytic boron nitride (see Patent Documents 4 and 5).

[0004] This resistance heating method, which utilizes electrostatic adsorption, is highly pure, chemically stable, and resistant to thermal shock, making it suitable for use in various fields requiring rapid temperature increases and decreases. For example, it is widely used in the semiconductor wafer manufacturing field, specifically in processes where semiconductor wafers are processed one by one in a single-wafer format, with the temperature being changed in stages during processing. This multilayered heating device with electrostatic adsorption capabilities has the advantage of being able to use the Johnsen-Rabek force over a wide temperature range from room temperature to 700°C because the resistivity of the insulating layer on which the wafer is placed is low, and its use is expanding in semiconductor manufacturing processes.

[0005] Previously, heating devices with electrostatic adsorption capabilities containing pyrolysis boron nitride had the power supply terminals and power supply wiring (power wiring) for supplying power to the heating layer fixed with bolts and nuts. However, with this method, the bolts did not come into contact with the wafer, creating a gap between them and the wafer, which caused a drop in temperature. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 52-67353 [Patent Document 2] Japanese Patent Application Publication No. 59-124140 [Patent Document 3] Japanese Unexamined Patent Publication No. 4-124076 [Patent Document 4] Japanese Patent Application Publication No. 5-129210 [Patent Document 5] Japanese Patent Application Publication No. 7-10665 [Overview of the project] [Problems that the invention aims to solve]

[0007] In recent years, there has been a demand for improved heat uniformity in high-temperature processes exceeding 200°C during the manufacturing of semiconductor devices. The main cause of decreased heat uniformity is the non-contact areas between the wafer and the wafer mounting surface of the heating device, specifically the holes of through-holes and the outermost periphery of the wafer mounting surface. When the wafer and the wafer mounting surface are not in contact, heat is dissipated from these areas, causing the wafer temperature to drop. [Means for solving the problem]

[0008] In order to solve the above problem, the inventors investigated the cause of the temperature drop on the wafer mounting surface and found that by having a power supply terminal section for supplying power to the heat-generating layer without a through hole connecting to the wafer mounting surface, and by providing a positioning recess in the power supply terminal section, the generation of sparks due to misalignment between the power supply wiring and the power supply terminal section can be suppressed. They found that the problem can be solved with the following configuration. That is, the present invention is as follows.

[0009] [1] A heating device having an electrostatic adsorption function, comprising at least a support substrate, an electrostatic adsorption electrode and a heating layer formed on the support substrate, an insulating layer containing boron nitride formed on the electrostatic adsorption electrode and the heating layer, and a power supply terminal for supplying power to the heating layer, The power supply terminal section has a structure that does not have a through hole connecting to the wafer mounting surface. A heating device having an electrostatic adsorption function, characterized in that the power supply wiring is fixed to the power supply terminal portion by a spring terminal. [2] The heating device having electrostatic adsorption function according to [1], characterized in that the power supply terminal portion is provided with a recess for positioning the spring terminal. [3] The heating device having an electrostatic adsorption function as described in [2], characterized in that the ratio of the outer diameter D1 / height h1 of the recessed portion is 0.1 or more and 10 or less. [4] The heating device having electrostatic adsorption function according to [2] or [3], characterized in that the recessed portion is formed by removing the heating layer. [5] A heating device having an electrostatic adsorption function as described in any of [2] to [4] above, characterized in that the ratio of the outer diameters (D2 / D1) of the outer diameter D1 of the recessed portion to the outer diameter D2 of the exposed portion of the power supply terminal portion is 1.2 or more and 100 or less. [6] A heating device having an electrostatic adsorption function according to any one of [1] to [5], characterized in that it is fixed by inserting a plastic washer between the power supply terminal and the spring terminal. [7] The insulating layer formed on the electrostatic adsorption electrode has a ratio (ρsE / ρsS) of the surface resistivity of the electrostatic adsorption electrode side portion (ρsE) to the surface resistivity of the object to be adsorbed side portion (ρsS) which is greater than 1 and 100 or less, and ρsE and ρsS are each 1 × 10 8 The surface resistivity of the intermediate portion is 2 × 10⁻¹⁰ or greater, and the surface resistivity of the intermediate portion is 2 × 10⁻¹⁰. 8 ~9×10 14 A heating device having electrostatic adsorption function as described in any of [1] to [6] above, characterized in that it is formed to a thickness of 50 to 300 μm and has an Ω / □ ratio. [8] The insulating layer formed on the electrostatic adsorption electrode has a surface resistivity (Ω / □) in the planar direction of the insulating layer, where A is the volume resistivity (Ω·cm) in the thickness direction of the insulating layer, and B is the volume resistivity (Ω·cm) in the thickness direction of the insulating layer, wherein the ratio of the surface resistivity to the volume resistivity (A / B) is 0.01 or more and 10,000 or less, and the volume resistivity in the thickness direction of the insulating layer is 10 6 ~10 15 A heating device having an electrostatic adsorption function according to any one of the above [1] to [7], characterized in that it consists of components having a value of Ω·cm. [9] A heating device having an electrostatic adsorption function according to any one of [1] to [8], characterized in that the electrostatic adsorption electrode and / or the heating layer is made of pyrolysis graphite containing boron and / or boron carbide in a boron concentration range of 0.001 to 30% by mass.

[10] The heating device having an electrostatic adsorption function according to any one of [1] to [9], characterized in that the electrostatic adsorption electrode and / or the heating layer are formed via a protective layer formed on the support substrate.

[11] The heating device having the electrostatic adsorption function according to

[10] , wherein the protective layer is made of any one of silicon nitride, boron nitride, aluminum nitride, and pyrolytic boron nitride.

[12] The heating device having the electrostatic adsorption function according to any one of [1] to

[11] , wherein the support substrate is mainly composed of any one of a silicon nitride sintered body, a boron nitride sintered body, a mixed sintered body of boron nitride and aluminum nitride, an alumina sintered body, an aluminum nitride sintered body, pyrolytic boron nitride, and pyrolytic boron nitride-coated graphite.

[13] A manufacturing method of a heating device having the electrostatic adsorption function according to any one of [1] to

[12] , wherein the insulator layer is formed by changing the resistivity in a gradient manner in the thickness direction by a chemical vapor deposition method.

Effect of the Invention

[0010] According to the present invention, in the power supply terminal portion for supplying power to the heat generating layer, by adopting a structure without a through hole connected to the wafer placement surface, there is no through hole that causes a temperature drop of the wafer, and the contact area with the wafer increases. Therefore, the heat uniformity of the wafer placement surface is improved, and the temperature distribution of the wafer is improved. Further, by providing a recess for positioning the spring terminal in the power supply terminal portion and pressing the spring terminal thereagainst, a heating device having an electrostatic adsorption function capable of further improving the heat uniformity of the wafer placement surface can be provided. Therefore, in the manufacturing process of a device or the like, if the wafer is heated using this heating device, the yield of the device is improved, and it can be used stably over a long period of time.

Brief Description of the Drawings

[0011] [Figure 1] It is a conceptual diagram of a heating device having an electrostatic adsorption function manufactured in Example 1. [Figure 2] It is a conceptual diagram of a heating device having an electrostatic adsorption function manufactured in Comparative Example 1. [Figure 3] It is a plan explanatory diagram for explaining the outer diameter D1 of the recess 9 and the outer diameter D2 of the exposed portion of the power supply terminal portion. [Figure 4]This is a cross-sectional diagram illustrating the electrostatic adsorption electrode side and the adsorbed object side of the insulating layer. [Modes for carrying out the invention]

[0012] Embodiments of the present invention will be described in detail below with reference to the drawings, but the present invention is not limited to these embodiments. In each drawing, the same or corresponding parts are denoted by the same reference numerals.

[0013] The heating device of the present invention is a heating device that has an electrostatic adsorption function for holding and fixing a semiconductor wafer, which is the object to be heated, while heating it, and is used in CVD equipment, sputtering equipment, or etching equipment for etching the generated thin film in the manufacturing process of semiconductor devices.

[0014] The heating device 1 of the present invention includes at least a support substrate 2, an electrostatic adsorption electrode 4 and a heating layer 5 formed on the support substrate, an insulating layer 3 formed on the electrostatic adsorption electrode and the heating layer, and a power supply terminal portion 7 for supplying power to the heating layer, and has an electrostatic adsorption function. The power supply terminal portion 7 for supplying power to the heating layer 5 is characterized in that it does not have a through hole 11 that connects to the wafer mounting surface. Furthermore, the power supply terminal portion 7 for supplying power to the heating layer 5 is provided with a recess portion 9 for positioning a spring terminal 8 (hereinafter sometimes simply referred to as "positioning recess portion" or "recess portion"), and the protrusion (tip) of the spring terminal 8 is inserted into the recess, and the power supply wiring is fixed by pressing the spring terminal 8 against the power supply terminal portion 7.

[0015] Here, the power supply terminal section 7 refers to the part where the terminal (power supply wiring) for supplying power to the heating layer 5 makes contact, and a portion of the heating layer 5 is exposed without being covered by the insulating layer 3. In the conventional technology, the power supply wiring and the power supply terminal section 7 were fixed with bolts 12 and nuts 13, etc.

[0016] Furthermore, the positioning recess 9 is a recessed portion provided in the power supply terminal 7, and is used to accurately position the spring terminal 8 and press the power supply wiring against the power supply terminal 7 to secure it. This stabilizes the position of the power supply terminal 7 to which the power supply wiring is connected, improving electrical contact.

[0017] Furthermore, the through-hole 11 is a hole that, in the conventional technology, was provided for inserting a bolt 12 to fix the power supply wiring to the power supply terminal 7 in order to supply power to the heating layer 5 for fixing the power supply terminal 7. In the present invention, this through-hole 11 is omitted.

[0018] <Heating device with electrostatic adsorption function> Figure 1 shows an example of a heating device having an electrostatic adsorption function according to the present invention. In this heating device having an electrostatic adsorption function (hereinafter sometimes simply referred to as "heating device") 1, an electrostatic adsorption electrode 4 and a heating layer 5 are formed on a disc-shaped support substrate 2 via a protective layer 6, and an insulating layer 3 is further formed on the electrostatic adsorption electrode 4 and the heating layer 5. The electrostatic adsorption electrode 4 is formed on the wafer mounting surface side of the support substrate 2, and the heating layer 5 is formed on the other side of the support substrate 2, i.e., on the side opposite to the wafer mounting surface. At least one power supply terminal portion 7 and its recess 9 are provided on the heating layer 5 side of the support substrate 2, and the depth of the recess 9 reaches halfway through the support substrate 2 but does not penetrate to the wafer mounting surface. Furthermore, the insulating layer 3 on the heating layer 5 is open so as to surround the area of ​​the recessed portion 9, and the area around the recessed portion 9 where the heating layer 5 is exposed becomes the terminal portion (the terminal portion that comes into contact with the power supply wiring) of the power supply terminal portion 7 for supplying power from the spring terminal 8 to the heating layer 5.

[0019] When heating a semiconductor wafer, the wafer is adsorbed and fixed onto the insulating layer 3 on the front side of the support substrate 2 by electrostatic adsorption electrodes 4, and heated by the conductive heating layer 5 on the back side of the support substrate 2.

[0020] Conventional heating devices used a method of fixing the power supply terminal 7 and power supply wiring for supplying power to the heating layer 5 with bolts 12 and nuts 13. However, because the bolts 12 did not come into contact with the wafer, a gap was created between them, causing a drop in temperature.

[0021] In contrast, the heating device of the present invention has a structure in which the power supply terminal section 7 for supplying power to the heating layer 5 does not have a through hole that connects to the wafer mounting surface. Furthermore, the power supply terminal 7 is provided with a recessed section 9 for positioning the spring terminal. By inserting a spring terminal 8 with a convex tip into the recessed section 9 and pressing the power supply wiring against the power supply terminal section 7, the spring terminal 8 is less likely to shift position, thereby suppressing the generation of sparks due to misalignment (Figure 1).

[0022] The following describes in detail each component of the heating device 1 of the present invention.

[0023] <Supporting base material> The material constituting the support base material 2 is not particularly limited, but it is preferably composed of a silicon nitride sintered body, a boron nitride sintered body, a mixed sintered body of boron nitride and aluminum nitride, an alumina sintered body, an aluminum nitride sintered body, and graphite. These materials have stable physical properties even in the medium to high temperature range of 500 to 800°C, and graphite is particularly desirable because it is stable up to high temperatures of 2000°C or higher.

[0024] Furthermore, the shape of the support base material 2 is not particularly limited and may be, for example, disc-shaped, cylindrical, or disc-shaped or cylindrical with convex or concave parts.

[0025] <Protective layer> The protective layer 6 formed on the support substrate 2 prevents impurities, gases, etc. contained in the support substrate 2 from affecting the subsequent manufacturing process. Such a protective layer 6 is essential to ensure insulation when the support substrate 2 is made of, for example, graphite, and is also necessary to prevent oxidation.

[0026] On the other hand, if the support substrate 2 is an insulator, the protective layer 6 does not necessarily have to be formed, but it is preferable to form the protective layer 3 because it can prevent contamination by impurities such as those mentioned above.

[0027] The material of the protective layer 6 is preferably one that is stable up to high temperatures, and examples include silicon nitride, boron nitride, pyrolysis boron nitride, and aluminum nitride. Furthermore, regarding the thickness of the protective layer 6, if it is too thick, it is prone to peeling due to the difference in thermal expansion with the supporting substrate, and if it is too thin, impurities, gases, etc. may permeate through pinholes, potentially adversely affecting the subsequent manufacturing process. From these viewpoints, the thickness of the protective layer 6 is preferably in the range of 10 to 500 μm, and particularly preferably 30 to 300 μm.

[0028] <Electrodes and heating layers for electrostatic adsorption> The electrostatic adsorption electrode 4 and the heating layer 5 are formed via a protective layer 6 formed on the support substrate 2. Preferably, the material is pyrolysis graphite containing boron and / or boron carbide in a boron concentration range of 0.001 to 30% by mass. The electrostatic adsorption electrode 4 and the heating layer 5 formed in this way have a stronger anchoring effect. Therefore, the insulating layer 3 formed on the electrostatic adsorption electrode 4 and the heating layer 5 adheres well to and bonds with the electrostatic adsorption electrode 4 and the heating layer 5, and peeling of the insulating layer 3 can be prevented even with repeated heating and cooling.

[0029] Furthermore, pyrolysis graphite containing boron and / or boron carbide within the above range has the property of reducing the temperature dependence of resistivity. Therefore, using it in the heating layer 5 improves temperature control, that is, it results in a good temperature distribution on the wafer, excellent thermal shock resistance, and the advantage that peeling of the insulating layer 3 is less likely to occur even with repeated heating and cooling. Moreover, even in the medium to high temperature range of 500 to 800°C, the resistance value is appropriate and sufficient electrostatic adsorption force is present, and there is no device damage due to leakage current, no dielectric breakdown occurs, and the heating device 1 has an electrostatic adsorption function that can be used stably even with rapid heating and cooling. When the boron concentration is 0.001 mass% or higher, a sufficient anchoring effect is obtained, while when it is 30 mass% or lower, grain growth is not excessive, sufficient film formation is observed, and the electrostatic adsorption electrode 4 and heating layer 5 can fully perform their functions.

[0030] The thickness of the electrostatic adsorption electrode 4 and the heating layer 5 is not particularly limited, but is preferably in the range of 10 to 500 μm, and particularly desirable to be in the range of 30 to 300 μm. With electrostatic adsorption electrode 4 and heating layer 5 of this thickness, objects to be heated, such as wafers, can be suitably electrostatically adsorbed and heated.

[0031] <Power supply terminal section> Furthermore, in this invention, the power supply terminal portion 7 for supplying power to the heating layer 5 is provided with a recess 9 for positioning the spring terminal, and the tip of the spring terminal 8 is inserted into this recess and pressed against it. As a result, the spring terminal 8 is less likely to shift position, and the generation of sparks due to misalignment is suppressed. In other words, the recess 9 is used for positioning in order to fix the spring terminal 8 and the power supply terminal portion 7.

[0032] In the present invention, there are two methods for providing the recessed portion 9 in the power supply terminal portion 7: one is to create a recessed shape in the carbon substrate and then perform CVD film deposition, and the other is to perform CVD film deposition first and then create the recess by machining. The former method, which involves creating a recessed shape in the carbon substrate and then performing CVD film deposition, is preferable because it causes less damage to the protective layer 6 and the insulating layer 3 due to machining.

[0033] Regarding the shape of the recess 9, it is preferable that the ratio of the outer diameter D1 to the height h1 of the recess 9 is 0.1 or more and 10 or less, from the viewpoint of inserting the tip of the spring terminal 8 into the recess 9 and properly fixing the power supply terminal 7 and the power supply wiring, and it is even more preferable that it is 5 or less. If it is greater than 10, the insulating layer inside the hole tends to become thinner, and the probability of sparking due to dielectric breakdown increases. Note that the outer diameter D1 of the recess 9 refers to the length of the outer surface of the recess 9, as shown in Figure 1, and the height h1 of the recess 9 refers to the length in the thickness direction of the recess 9.

[0034] Furthermore, it is preferable that the heat-generating layer 5 is removed from the recessed portion 9, that is, that the heat-generating layer 5 is not present in the recessed portion 9 (in Figure 1, the recessed portion 9 is a non-conductive layer 10). This is because if the convex portion of the spring terminal 8 rubs against the insulating layer 3, the heat-generating layer 5 will be exposed, causing sparks. Therefore, it is preferable to remove it during pattern processing after the heat-generating layer coating.

[0035] The outer diameter ratio D2 / D1 between the outer diameter D1 of the recessed portion 9 and the outer diameter D2 of the exposed portion of the power supply terminal portion 7 is preferably 1.2 or more and 100 or less, and more preferably 2 or more and 10 or less. If the outer diameter D1 of the recessed portion 9 is too small compared to the outer diameter D2 of the exposed portion of the power supply terminal portion 7, the convex portion of the spring terminal 8 will not fit properly, causing misalignment. On the other hand, if the outer diameter D1 of the recessed portion 9 is too large compared to the outer diameter D2 of the exposed portion of the power supply terminal portion 7, the area of ​​the terminal portion that contacts the power supply wiring will decrease, preventing large currents from flowing. Note that the outer diameter D2 of the exposed portion of the power supply terminal portion 7 refers to the outer diameter of the entire power supply terminal portion 7, as can be seen in Figure 3.

[0036] <Spring terminal> As shown in Figure 1, the spring terminal 8 generally consists of a fixed spring support portion 8a, an arc-shaped spring portion 8b, and a movable spring portion 8c. Due to the elastic deformation of the arc-shaped spring portion 8b, the movable spring portion 8c is displaced vertically relative to the spring support portion 8a. By inserting the spring terminal 8, which has a convex tip, into the recess 9 of the power supply terminal portion 7 and pressing the power supply wiring against the power supply terminal portion 7, the power supply wiring is fixed to the power supply terminal portion 7 by the spring terminal 8. However, the movable spring portion 8c is not essential, and the fixed spring support portion 8a and the arc-shaped spring portion 8b may be directly joined by welding or brazing. The linear thickness of the arc-shaped spring portion 8b is preferably 0.5 mm to 5.0 mm, and more preferably 0.5 mm to 3.0 mm. Furthermore, a plastic washer, such as a carbon washer, may be placed between the fixed-side spring support portion 8a and the power supply terminal portion 7. This makes it less likely for a gap to form between the fixed-side spring support portion 8a and the power supply terminal portion 7, which helps to suppress sparks. The spring terminal 8 is usually formed by sheet metal processing such as punching or bending using a mold, or by brazing. The spring terminal is formed from a high heat-resistant material such as SUS, Ni, Mo, W, or Inconel.

[0037] <Insulating layer> The insulating layer 3 formed on the electrostatic adsorption electrode 4 and the heating layer 5 is 10 6 ~10 15 It is preferable that the insulating layer 3 has an electrical resistivity of Ω·cm. If an insulating layer 3 having an electrical resistivity in this range is formed, the resistance value will be appropriate in the medium-high temperature range of 500°C to 800°C, preventing device damage due to leakage current and allowing sufficient electrostatic adsorption force to be obtained. Such an insulating layer 3 can preferably be made of pyrolysis boron nitride.

[0038] The thickness of the insulating layer 3 is not particularly limited, but is preferably in the range of 50 to 500 μm, and particularly desirable to be in the range of 70 to 300 μm. Generally, when an insulating layer 3 with a thickness of 50 to 500 μm is formed, if the bonding surface of the electrostatic adsorption electrode 4 or the heating layer 5 is smooth, it will easily peel off due to the difference in thermal expansion coefficients. However, in the present invention, since the electrostatic adsorption electrode 4 and the heating layer 5 which have a strong anchoring effect are formed, peeling of the insulating layer 3 is prevented even when repeated heating and cooling is performed. Furthermore, by using an insulating layer 3 of the above thickness, sufficient insulating force is achieved, and the electrical resistivity remains at an appropriate level even in the medium-high temperature range of 500 to 800°C, thus maintaining sufficient electrostatic adsorption force.

[0039] In the present invention, in a heating device 1 having the above configuration and electrostatic adsorption function, as shown in Figure 4, the insulating layer 3 covering the electrostatic adsorption electrode 4 has a surface resistivity ρsS on the object-to-adsorbed side portion (nearest portion) 3a-2 that is smaller than the surface resistivity ρsE on the electrostatic adsorption electrode side portion (nearest portion) 3a-1. As a result, there is no residual adsorption of the wafer immediately after the applied voltage is turned off, and the non-heated material can be peeled off.

[0040] Furthermore, the ratio (ρsE / ρsS) of the surface resistivity ρsE of the electrostatic adsorption electrode side portion (nearest portion) 3a-1 to the surface resistivity ρsS of the object to be adsorbed side portion (nearest portion) 3a-2 is greater than 1 and less than or equal to 100, and ρsE and ρsS are set to 1 × 10⁻¹⁰ each. 8 By setting the ratio to Ω / □ or higher, sufficient electrostatic adsorption force can be achieved from near room temperature to high temperatures. In Figure 4, 3a-3 is the intermediate part of the insulating layer 3 covering the electrostatic adsorption electrode 4.

[0041] Here, the electrostatic adsorption electrode side portion (nearest portion) 3a-1 refers to the portion up to 50 μm inward (towards the object to be adsorbed) from the surface of the electrostatic adsorption electrode 3, and the object to be adsorbed side portion (nearest portion) 3a-2 refers to the portion up to 50 μm inward (towards the electrostatic adsorption electrode) from the outer surface of the insulating layer 3 covering the electrostatic adsorption electrode.

[0042] Also, the thickness of the insulator layer 3 covering the heat generating layer 5 is preferably 50 to 300 μm, particularly preferably 80 to 200 μm.

[0043] In the present invention, as described above, the surface resistivity ρsS of the adsorbed object side portion 3a-2 can be made smaller than the surface resistivity ρsE of the electrostatic adsorption electrode side portion 3a-1. However, ρsE and ρsS are each 1×10 8 Ω / square or more, preferably 1×10 8 Ω / square to 1×10 14 Ω / square, more preferably 1×10 9 Ω / square to 1×10 14 Ω / square, even more preferably 1×10 10 Ω / square to 1×10 14 Ω / square, and it is desirable that they are.

[0044] Also, it is desirable that ρsE / ρsS is greater than 1 and 100 or less, more preferably greater than 1 and 10 or less. The surface resistivity of the intermediate portion 3a-3 can be 2×10 8 ~9×10 14 Ω / square, and it is preferable to take a value intermediate between ρsE and ρsS

[0045] In the heating device of the present invention, when the temperature at the time of wafer adsorption is such that the surface resistivity (Ω / square) in the plane direction of the insulator layer 3 is A and the volume resistivity (Ω·cm) in the thickness direction of the insulator layer 3 is B, the ratio (A / B) of the surface resistivity to the volume resistivity can be 0.01 or more. If this ratio is less than 0.01, no electrostatic adsorption force is generated, and in the worst case, dielectric breakdown may occur between the electrodes of the bipolar structure, resulting in a problem that the electrostatic adsorption function cannot be exhibited. This is considered to be because the ratio of the leakage current directly passing through the insulator layer 3 between the electrodes of the bipolar structure increases, and the leakage current to the wafer contributing to wafer adsorption decreases, so the electrostatic adsorption force decreases. Therefore, by setting the ratio (A / B) of the surface resistivity to the volume resistivity to 0.01 or more, preferably 0.1 or more, dielectric breakdown does not occur between the bipolar electrodes, and a practically sufficient electrostatic adsorption force is generated, eliminating the above problem.

[0046] Furthermore, the upper limit of the ratio (A / B) of the surface resistivity to the volume resistivity is not particularly limited, but is usually 100,000 or less, and is particularly preferable to be 10,000 or less in order to ensure the dielectric strength between the electrode and the wafer.

[0047] Means for changing or adjusting the ratio (A / B) of the surface resistivity to the volume resistivity include, for example, adding and dispersing impurities in the insulating layer 3 to give it anisotropy, or giving it crystalline orientation by annealing, or, when forming the insulating layer 3 by vapor phase growth, changing the type of raw material gas, reaction temperature, reaction pressure, etc.

[0048] <Method of manufacturing a heating device> The method for manufacturing the heating device having electrostatic adsorption function according to the present invention is not particularly limited, but it can be suitably manufactured by chemical vapor deposition. For example, when forming an electrostatic adsorption electrode 4 and a heating layer 5, methane gas is reacted under conditions of 1000 to 2500°C and 1 to 10 Torr, and boron halide is introduced into the same reaction chamber at a boron concentration of 0.001 to 30% by mass to form a pyrolysis graphite layer on a support substrate 2 made of graphite having a protective layer 6 on its surface, for example. Then, this pyrolysis graphite layer can be processed so that the front side of the support substrate 2 has the pattern of the electrostatic adsorption electrode 4 and the back side has the pattern of the heating layer 5.

[0049] By forming an electrostatic adsorption electrode 4 and a heating layer 5 made of pyrolysis graphite containing boron and / or boron carbide in a boron concentration range of 0.001 to 30% by chemical vapor deposition, minute irregularities are formed on the surface, which can exhibit a very excellent anchoring effect and effectively prevent the peeling of the insulating layer 3 formed thereon.

[0050] It is preferable that the protective layer 6 and the insulating layer 3 are also formed in the same manner by chemical vapor deposition. Each of these layers formed by chemical vapor deposition has high purity and suppresses peeling and particle generation. As mentioned above, the protective layer 6 is not essential depending on the support substrate 2. In this case, as shown in Figure 4, the electrostatic adsorption electrode 4 and the heating layer 5 (not shown) may be formed directly on the support substrate 2, and the heating device with electrostatic adsorption function can be made with the same configuration as in Figure 1.

[0051] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited thereto. Furthermore, the present invention is not limited to the embodiments described herein. These embodiments are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and achieves similar effects is included within the technical scope of the present invention. For example, the shapes of the support substrate, electrostatic adsorption electrodes, and heating layer are not limited to those shown in Figures 1 and 2. [Examples]

[0052] (Example 1) A graphite substrate was prepared, coated with a protective layer 6 made of pyrolysis boron nitride, with a diameter of 200 mm and a thickness of 15 mm. Next, methane gas was thermally decomposed on the protective layer 6 under conditions of 2200°C and 5 Torr, and boron halide (boron trichloride) was introduced into the same reaction chamber at a boron concentration ranging from 0.001 to 30% by mass, thereby forming a 100 μm thick pyrolysis graphite layer containing a mixture of boron and boron carbide. The surface side of this pyrolysis graphite layer was processed into an electrode pattern to serve as an electrostatic adsorption electrode 4, and the back side was processed into a heater pattern to serve as a heating layer 5. The power supply terminal portion 7 for the heat-generating layer 5 does not have a through hole 11 connecting to the wafer mounting surface. Furthermore, the power supply terminal portion 7 for supplying power to the heat-generating layer 5 is provided with a recess 9 for positioning the spring terminal 8. By inserting the tip of the spring terminal 8 into this recess 9 and pressing it against it, a stable electrical connection is achieved. The ratio of the outer diameter D1 to the height h1 of the recess 9 was 0.5. Also, the ratio of the outer diameter D1 of the recess 9 to the outer diameter D2 of the exposed portion of the power supply terminal portion 7 (D2 / D1) was 2.0. Note that the heat-generating layer 5 is removed and does not exist in the recess 9. Subsequently, ammonia, boron trichloride, and methane were reacted on both surfaces at 1600°C under conditions of 5 Torr to form an insulating layer 3 containing carbon-containing pyrolysis boron nitride with a thickness of 200 μm, thereby fabricating a heating device with electrostatic adsorption functionality. The surface resistivity (ρsS) of the adsorbed material side was 2.9 × 10⁻⁶. 8 The coefficient is (Ω / □), and the volume resistivity in the thickness direction is 9.5 × 10⁻⁶. 9 The result was (Ω·cm), and the ratio (surface resistivity / volume resistivity) was 11.9. The wafer was adsorbed by applying a voltage of ±500V between the bipolar electrodes while the temperature was raised to 600℃. When the temperature distribution of the wafer was checked with a thermograph, no temperature drop originating from the power supply terminal portion 7 or the positioning recess portion 9 was observed, indicating excellent heat uniformity. Subsequently, the insulating layer 3 of the sample was divided into the portion closest to the object to be adsorbed and the portion closest to the electrostatic adsorption electrode, and samples for resistivity measurement were cut out and the surface resistivity was measured. The thickness of each sample was 50 μm. The surface resistivity (ρsE) of the portion on the electrostatic adsorption electrode side was 3.2 × 10⁻⁶. 9 It was (Ω / □). Surface resistivity was measured in accordance with the JIS standard (K6911-1995 5.13 Resistivity). The measuring instrument used was a Dia Instruments Hi-Lester IP MCP-HT260, and an HRS probe was used. The measurements were taken from near the center of a heating device with electrostatic adsorption capabilities, under room temperature conditions of 25°C and 50% humidity.

[0053] (Example 2) A heating device having the same electrostatic adsorption function as in Example 1 was manufactured, except that the ratio of the outer diameter D1 / height h1 of the recessed portion 9 was set to 2.0, and the ratio of the outer diameter D1 of the recessed portion 9 to the outer diameter D2 of the exposed portion of the power supply terminal (D2 / D1) was set to 5.0. The obtained heating device was subjected to the same tests as in Example 1, and the temperature distribution of the wafer was confirmed using thermography. No temperature drop originating from the power supply terminal portion 7 and the positioning recess portion 9 was observed, indicating excellent uniform heating performance.

[0054] (Comparative Example 1) As shown in Figure 2, the power supply terminal section 7 for supplying power to the heating layer 5 has a structure in which a through hole 11 into which a bolt is inserted, and the power supply terminal section 7 for supplying power to the heating layer does not have a positioning recess 9, and instead of a spring terminal 8, the power supply wiring is fixed with a bolt 12 and nut 13 as in the conventional structure, but otherwise a heating device with electrostatic adsorption function was manufactured in the same manner as in Example 1. The obtained heating device was subjected to the same tests as in Example 1, and the temperature distribution of the wafer was confirmed using thermography. A temperature drop of -20°C was observed at the power supply terminal 7 and the through-hole 11, resulting in inferior heat uniformity compared to Example 1.

[0055] (Comparative Example 2) A heating device having the same electrostatic adsorption function as in Example 1 was fabricated, except that the ratio of the outer diameter D1 / height h1 of the recessed portion was set to 20. When the obtained heating device was subjected to the same tests as in Example 1, dielectric breakdown occurred between the recessed portion 9 and the protruding portion of the spring terminal because the insulating layer inside the hole was thin, resulting in lower reliability compared to Example 1.

[0056] (Comparative Example 3) A heating device having the same electrostatic adsorption function as in Example 1 was fabricated, except that the ratio of the outer diameters (D2 / D1) between the outer diameter D1 of the recessed portion and the outer diameter D2 of the exposed portion of the power supply terminal was set to 1.05. When the obtained heating device was subjected to the same tests as in Example 1, sparks were observed at the terminals due to the small contact area with the current, resulting in lower reliability compared to Example 1. [Industrial applicability]

[0057] According to the present invention, unlike the conventional technology, the power supply terminal portion for supplying power to the heating layer has a structure without a through hole connecting to the wafer mounting surface. Instead, the power supply terminal portion for the heating layer is provided with a recess for positioning the spring terminal. This eliminates the through hole that causes a decrease in wafer temperature, and further improves contact with the spring terminal, resulting in improved wafer temperature distribution and improved heat uniformity. Furthermore, the present invention provides excellent anchoring effects for the electrostatic adsorption electrode and heating layer. The boron added to the electrostatic adsorption electrode and heating layer chemically bonds with the nitrogen in the protective layer and insulating layer, resulting in a strong bond and eliminating the problem of peeling of the insulating layer. Moreover, even in the medium to high temperature range of 500 to 800°C, the insulating layer has an appropriate resistance value and sufficient electrostatic adsorption force, and the heating device can be configured to have electrostatic adsorption functionality without device damage due to leakage current. [Explanation of Symbols]

[0058] 1. Heating device with electrostatic adsorption function 2 Supporting base material 3. Insulator layer 3a-1 Electrostatic adsorption electrode side portion of the insulating layer covering the electrostatic adsorption electrode 3a-2 Portion of the insulating layer covering the electrostatic adsorption electrode on the side facing the object to be adsorbed 3a-3 Intermediate portion of the insulating layer covering the electrostatic adsorption electrode 4. Electrodes for electrostatic adsorption 5. Heating layer 6 Protective layer 7 Power supply terminal section 8 Spring terminals 8a Fixed spring support section 8b Arc-shaped spring section 8c Movable side spring section 9. Recessed area for positioning the spring terminal. 10 Non-current carrying layer 11 Through hole 12 volts 13 nuts

Claims

1. A heating device having an electrostatic adsorption function, comprising at least a support substrate, electrostatic adsorption electrodes and a heating layer formed on the support substrate, an insulating layer containing boron nitride formed on the electrostatic adsorption electrodes and the heating layer, and a power supply terminal for supplying power to the heating layer, The power supply terminal section has a structure that does not have a through hole connecting to the wafer mounting surface. The power supply wiring is secured to the aforementioned power supply terminal section by a spring terminal. A heating device having an electrostatic adsorption function, characterized in that it is fixed by inserting a plastic washer between the power supply terminal and the spring terminal.

2. The heating device having an electrostatic adsorption function according to claim 1, characterized in that the power supply terminal portion is provided with a recess for positioning the spring terminal.

3. A heating device having an electrostatic adsorption function according to claim 2, characterized in that the ratio of the outer diameter D1 / height h1 of the recessed portion is 0.1 or more and 10 or less.

4. The heating device having electrostatic adsorption function according to claim 2, characterized in that the recessed portion is formed by removing the heating layer.

5. A heating device having an electrostatic adsorption function according to claim 2, characterized in that the ratio of the outer diameters (D2 / D1) of the outer diameter D1 of the recessed portion and the outer diameter D2 of the exposed portion of the power supply terminal portion is 1.2 or more and 100 or less.

6. The heating device having an electrostatic adsorption function according to Claim 1, characterized in that the insulating layer formed on the electrostatic adsorption electrode has a ratio (ρsE / ρsS) of the surface resistivity of the portion on the electrostatic adsorption electrode side (ρsE) to the portion on the object to be adsorbed side (ρsS) which is greater than 1 and 100 or less, ρsE and ρsS are each 1 × 10⁸ Ω / □ or more, and the surface resistivity of the intermediate portion in the thickness direction is 2 × 10⁸ to 9 × 10¹⁴ Ω / □, and is formed to a thickness of 50 to 300 μm.

7. When the insulating layer formed on the electrostatic adsorption electrode has a surface resistivity (Ω / □) in the planar direction of the insulating layer (A / B) and a volume resistivity (Ω·cm) in the thickness direction of the insulating layer (A / B), the ratio of the surface resistivity to the volume resistivity (A / B) is 0.01 or more and 10,000 or less, and the volume resistivity in the thickness direction of the insulating layer is 10 ６ ~10 １５ A heating device having electrostatic adsorption function according to claim 1, characterized in that it consists of components having a value of Ω·cm.

8. The heating device having electrostatic adsorption function according to claim 1, characterized in that the electrostatic adsorption electrode and / or the heating layer is made of pyrolysis graphite containing boron and / or boron carbide in a boron concentration range of 0.001 to 30% by mass.

9. The heating device having an electrostatic adsorption function according to claim 1, characterized in that the electrostatic adsorption electrode and / or the heating layer are formed via a protective layer formed on the support substrate.

10. The heating apparatus having electrostatic adsorption function according to claim 9, characterized in that the protective layer is made of silicon nitride, boron nitride, aluminum nitride, and pyrolysis boron nitride.

11. The heating device having electrostatic adsorption function according to claim 1, characterized in that the support substrate mainly consists of a silicon nitride sintered body, a boron nitride sintered body, a mixed sintered body of boron nitride and aluminum nitride, an alumina sintered body, an aluminum nitride sintered body, pyrolysis boron nitride, or pyrolysis boron nitride coated graphite.

12. A method for manufacturing a heating device having electrostatic adsorption function according to claim 1, characterized in that the insulating layer is formed by chemical vapor deposition with a gradient change in resistivity in the thickness direction.

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