Susceptor for manufacturing semiconductor device

Abstract

A susceptor (1) for manufacturing a semiconductor device has a disk shape in which a first surface (1a) and a second surface (1b) made of single crystal silicon or polycrystalline silicon are parallel to each other, and the specific resistance value is preferably 10 Ω·cm or less. One or more recesses (2) for accommodating substrates subject to processing are formed in a substrate mounting surface (1a) of the first surface. The warpage measured on the substrate mounting surface side is preferably 20 μm or less, and the warpage is preferably formed in a direction in which the substrate mounting surface (1a) bulges.

Description

Susceptors for semiconductor device manufacturing

[0001] The present invention relates to a susceptor used in a semiconductor device manufacturing process. This application claims priority to Japanese Patent Application No. 2024-147140 filed on August 29, 2024, and Japanese Patent Application No. 2025-140621 filed on August 26, 2025, the contents of which are incorporated herein by reference.

[0002] Susceptors (also called transport carriers or trays) used in the semiconductor device manufacturing process are used as pedestals for placing wafers on them when processing them all at once in a large chamber, or when processing small-diameter wafers smaller than the diameters handled by semiconductor manufacturing equipment or cut-out wafers (also called chips) for development purposes.

[0003] Etching, plasma CVD, and ion implantation equipment, which require temperature control for film formation uniformity, have electrostatic chuck mechanisms and heater mechanisms on the mounting stage. These equipment perform processing inside a vacuum chamber, so a heat transfer mechanism is required for heat transfer. Conventional methods for heat transfer include embedding an electrode in the susceptor to use as an electrostatic chuck, hollowing out the entire backside of a small-diameter wafer and controlling the temperature with an electrostatic chuck, and applying thermal grease or a thermal sheet to the backside of the wafer. The susceptor material is selected depending on the equipment, and is made of alumina, SiN, SiC, carbon, graphite, or other materials.

[0004] For example, in Patent Document 1, the bottom surface in contact with the electrostatic chuck has a volume resistivity of 1×10 １３ The upper side exposed to plasma is made of a material with a volume resistivity of 1×10 １３ The paper discloses a tray (susceptor) made of a material with a resistivity exceeding Ω cm, and the underside of the tray is in close contact with a tray stage for thermal conduction. Specific materials include silicon carbide or aluminum nitride with dispersed conductive materials such as titanium carbide or carbon fiber for the lower layer, and alumina, quartz, aluminum nitride, yttria, zirconia, etc. for the upper layer.

[0005] Patent Document 2 discloses a transfer tray in which a recess corresponding to the outer shape of a substrate to be processed is formed on the substrate-mounting surface of a transfer tray (susceptor), and an annular sealing means is provided along the outer periphery of the bottom surface of the recess, and a pressing means is provided to press the outer periphery of the substrate to be processed placed in the recess against the sealing means, and a cooling gas can be supplied to the space behind the substrate to be processed placed in the recess through a gas passage leading to the recess. In this case, it is described that the transfer tray is made of a material such as silicon oxide, stainless steel, or aluminum.

[0006] Japanese Patent Application Publication No. 2018-10975 (A) Japanese Patent Application Publication No. 2008-171996 (A)

[0007] However, when alumina or other materials are used as susceptors, as in Patent Document 1, they have poor thermal conductivity and may crack if subjected to heat shock. To prevent cracking due to heat shock, preheating may be performed in a preheating chamber before the processing chamber, but this process is cumbersome. Furthermore, since insulating materials such as alumina cannot be electrostatically attracted using conventional electrostatic chucks such as Coulomb-type chucks, a metal plating film may be applied to the susceptor, but this raises concerns about metal contamination. In a structure using a sealing means or a pressing means, as in Patent Document 2, the sealing means impairs heat transfer to the outer periphery of the processing substrate, and the pressing means leaves part of the outer periphery unprocessed, resulting in a lower yield of device chips obtained from a single wafer. Furthermore, using a metal for the carrier tray raises concerns about metal contamination.

[0008] The present invention has been made in view of the above circumstances, and has an object to provide a susceptor for use in manufacturing semiconductor devices, which can be electrostatically chucked, has improved thermal conductivity, and can process the entire surface of a processing substrate such as a wafer with uniform precision.

[0009] The susceptor for manufacturing semiconductor devices of the present invention is formed in the shape of a plate having a first surface and a second surface, and is made of silicon.

[0010] Silicon has a higher thermal conductivity than alumina, silicon carbide, and other materials, and has a low resistivity, allowing it to be adsorbed by an electrostatic chuck. This allows the susceptor to be properly installed on the stage of the plasma processing apparatus, and the entire surface of the wafer placed on the susceptor is uniformly heated, making it possible to manufacture high-quality devices. Both single-crystal silicon and polycrystalline silicon can be used as silicon. The polycrystalline silicon in this embodiment includes columnar silicon.

[0011] The susceptor for semiconductor device manufacturing of the present invention preferably has a resistivity of 10 Ω cm or less. Because the susceptor has a low resistivity, it is easily attracted to an electrostatic chuck and can be widely used in various electrostatic chucks, including Coulomb-type chucks.

[0012] In the susceptor for manufacturing semiconductor devices of the present invention, the first surface is a substrate mounting surface, the second surface is placed on a surface plate, and the height of the first surface is measured. When the average value of center heights measured at multiple locations in a circular area within 1 / 3 of the diameter is defined as center height average value H1, the average value of annular region heights measured at multiple locations in an annular area outside the circular area surrounding the center region is defined as annular region height average value H2, and the average value of outer peripheral region heights measured at multiple locations in an area outside the annular region within 98% of the diameter, it is preferable that H1≧H2≧H3.

[0013] Such a height distribution results in either a flat planar shape as a whole or a dome-like curved shape with a convex central portion, which provides appropriate adhesion to an electrostatic chuck and excellent thermal conductivity.

[0014] In the susceptor for manufacturing semiconductor devices of the present invention, the diameter is preferably 200 mm to 450 mm, and the thickness is preferably 0.5 mm to 5 mm, and the standard deviation of each of the center height, the annular region height, and the outer peripheral region height is preferably 7 μm or less. Since the variation in height is small, the susceptor can be formed with a surface that is free of undulations and localized unevenness, thereby improving adhesion to an electrostatic chuck.

[0015] In the susceptor for manufacturing semiconductor devices of the present invention, the maximum height position of the space formed between the second surface and the surface plate is located on the second surface side in the central region, and the maximum height thereof is 20 μm or less. Since the height of the space formed between the second surface and the susceptor when placed on the surface plate is small, a substrate can be stably placed on the substrate placement surface.

[0016] In the susceptor for manufacturing semiconductor devices according to the present invention, the substrate mounting surface may be curved in a dome shape in a convex direction. When the susceptor is placed on a stage, the concave surface of the susceptor covers the stage surface, and gas supplied from below flows while remaining between the stage and the susceptor, thereby enabling efficient heat conduction.

[0017] In the susceptor for manufacturing semiconductor devices of the present invention, one or more recesses for accommodating a substrate to be processed are formed in the substrate mounting surface.

[0018] The susceptor for semiconductor device manufacturing of the present invention has high thermal conductivity, excellent thermal conductivity, and low resistivity, allowing it to be attracted by an electrostatic chuck. This allows the susceptor to be properly installed on the stage of a plasma processing apparatus, and the entire surface of a wafer placed on the susceptor is uniformly heated, enabling the production of high-quality devices.

[0019] 5A is a plan view showing a susceptor according to one embodiment of the present invention; FIG. 5B is a cross-sectional view taken along line AA in FIG. 1; FIG. 5C is a flowchart showing a method for manufacturing a susceptor according to one embodiment; FIG. 5D is a cross-sectional view showing a state in which a susceptor is placed on a stage of a plasma processing apparatus; FIG. 5E is a diagram for explaining a method for measuring the surface shape of a susceptor, showing a state in which the second surface is placed on a surface plate and measured; FIG. 5F is a diagram for explaining a method for measuring the surface shape of a susceptor, showing a state in which the first surface is placed on a surface plate and measured; FIG. 5G is a diagram showing a method for measuring the surface shape of a susceptor, showing measurement points on a plane; and FIG. 5G is a diagram showing the shapes measured by the method shown in FIG. 5A for four types of susceptors using different polishing methods in flattening processing.

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0021] A susceptor 1 for manufacturing semiconductor devices (hereinafter simply referred to as a susceptor) according to one embodiment is made of single crystal silicon or polycrystalline silicon, and is formed in the shape of a disk with a first surface 1a and a second surface 1b parallel to each other. In this embodiment, the susceptor made of silicon is mainly composed of silicon, and may contain inevitable impurities for adjusting the resistivity or the purity during production, or may contain dopants such as B or P. The susceptor 1 made of silicon has a thermal conductivity of 140 W / m K or more and 180 W / m K or less (for example, 160 W / m K) at room temperature of 27° C., and a resistivity of 1×10 －４ Ω・cm or more 1×10 ３ The specific resistance is 1×10 Ω·cm or less. ２ It is preferably Ω cm or less, and more preferably 1 x 10 Ω cm or less. The reason is that the thermal conductivity λ of silicon can be expressed as the sum of the thermal conductivity λe of electrons due to the amount of dopant, which is an electric carrier, and the thermal conductivity λp of silicon lattice vibration. The thermal conductivity of lattice vibration is affected by the influence of phonons, phonon boundary scattering, impurity scattering, and grain boundary scattering.

[0022] Therefore, based on physical principles, silicon that is excellent for silicon susceptors has a low dopant content to increase the thermal conductivity of electrons and large grain boundaries that prevent boundary scattering under the influence of phonons. In particular, to increase thermal conductivity, adding dopants to achieve a resistivity of approximately 10 Ω·cm improves the thermoelectric coefficient at low temperatures, achieving a value of 1000 W / m·K at -173°C. The first surface 1a serves as a substrate mounting surface, and multiple recesses 2 (three in the example shown in Figures 1 and 2) are formed on the first surface 1a to accommodate the processing substrate (wafer) W. The susceptor 1 has a substrate mounting surface and is used to transport and process substrates (e.g., wafers).

[0023] 5A, the second surface 1b of the susceptor 1 is placed on a base plate P, and the height of the first surface (substrate mounting surface) 1a is measured from above as indicated by the arrow using a laser displacement meter. As shown in FIG. 5C, when the average value of the central heights measured at multiple locations within a circular central region F1 up to 1 / 3 of the diameter D1 of the susceptor 1 (measurement points are indicated by M in the figure) is defined as a central height average value H1, the average value of the annular region heights measured at multiple locations within an annular region F2 surrounding the central region F1 outside the central region F1 is defined as an annular region height average value H2, and the average value of the outer periphery region heights measured at multiple locations within an outer periphery region F3 outside the annular region F2 up to 98% of the diameter D1 of the susceptor 1 is defined as an outer periphery region height average value H3, the relationship H1≧H2≧H3 is satisfied. That is, the susceptor 1 may have a flat planar shape (H1 = H2 = H3) as a whole, or a dome-shaped curved shape (H1 ≥ H2 > H3) or (H1 > H2 ≥ H3) such that the height gradually decreases from the center to the periphery. Alternatively, the susceptor 1 may have a dome-shaped curved shape (H1 > H2 > H3) such that the height gradually decreases from the center to the periphery. Note that the dome-shaped curved shape of the susceptor 1 may have a substantially flat portion within each of the above-described regions (F1, F2, F3).

[0024] Note that, as long as the heights H1 to H3 of the regions F1 to F3 are approximately equal, H1≧H2≧H3, H1≧H2≦H3, or H1≦H2≧H3 may be satisfied. In this case, it is sufficient that the height difference |H1−H2| or |H2−H3| is 0.4 μm or less, or |H1−H3| is 0.4 μm or less.

[0025] The standard deviation of the height of each of these regions is 7 μm or less, preferably 3 μm or less, and more preferably 2.5 μm or less.

[0026] In this case, the outer peripheral region F3 is set to within 98% of the diameter D1 of the susceptor 1 because the outer peripheral edge of the susceptor 1 is machined to round the edges, etc., and therefore has a small thickness, and this machined portion must be avoided from the measurement object.

[0027] It should be noted that, with regard to the measurement of the height, it is necessary to eliminate the influence of the flatness of the surface plate P. For example, before placing the susceptor 1, the height of the surface of the surface plate P is measured at multiple locations (for example, one point at the center and four points at 90° intervals in the outer regions) in the area where the central region F1 of the susceptor 1 is disposed and the area where the annular region F2 and the outer peripheral region F3 are disposed, and the surface obtained based on the measured values ​​is used as the reference surface of the surface plate P, and the height relative to this reference surface is measured, thereby eliminating the influence of the flatness of the surface plate P.

[0028] The maximum height (referred to as warpage) h from the surface plate P on the second surface 1b opposite to the substrate mounting surface 1a is 20 μm or less, and the susceptor is either flat and unwarped, or warped slightly convexly toward the substrate mounting surface 1a. The warpage h can be determined by measuring the height from the surface plate P on both surfaces (first surface 1a and second surface 1b) by scanning the entire surface of the susceptor with a laser using a laser scanning device, combining the measured values, and performing image processing and correction calculations to determine the amount of warpage.

[0029] Specifically, as in the case of the height measurement described above, the second surface 1b of the susceptor 1 is placed on a surface plate P as shown in FIG. 5A , and the height of the first surface 1a is measured at multiple locations (multiple locations for each of the central region F1, the annular region F2, and the peripheral region F3) without taking into account the influence of the flatness of the surface plate P. Next, the susceptor 1 is turned over and the first surface 1a is placed on the surface plate P as shown in FIG. 5B , and the height of the second surface 1b is measured at multiple locations without taking into account the influence of the flatness of the surface plate P. By subtracting the thickness of the susceptor 1 from the difference between the measurements at the same location on the plane, the height distribution of the space S (see FIG. 5A ) between the second surface 1b and the surface plate P when the second surface 1b is placed on the surface plate P can be determined. As described above, if the maximum value of the height of this space S is defined as the warpage h, this warpage h is 25 μm or less. The warpage can also be measured by placing a CNC (Computer Numerical Control) image measuring device or a CNC contact measuring device on a surface plate and measuring the height. It is more preferable that the warpage h is 20 μm or less. While not particularly limited, the warpage h may be 15 μm or less, or 10 μm or less. Furthermore, the warpage h may be 0.1 μm or more.

[0030] The dimensions of the susceptor 1 are not necessarily limited, but may be, for example, a disk-shaped structure having a diameter of 200 mm to 450 mm and a thickness of 0.5 mm to 5 mm. The diameter may be 220 mm to 280 mm or 320 mm to 430 mm. The recess 2 is circular and has a diameter of 50 mm to 200 mm and a depth of 0.25 mm to 1 mm. Therefore, the thickness of the bottom wall of the recess 2 is 0.25 mm to 4.75 mm. One to 30 recesses 2 are formed in one susceptor 1. The wafer (process substrate) W accommodated in the recess 2 is circular and has a diameter of 50 mm to 200 mm and a thickness of 0.220 mm to 1 mm.

[0031] The susceptor 1 configured as described above is manufactured from a silicon ingot through the steps shown in Fig. 3. Specifically, the ingot is sliced ​​into disks (cutting), heat-treated to remove distortion (heat treatment), machined to the outer shape by grinding or the like (shape processing (outer shape)), and the recess 2 is formed on the substrate mounting surface 1a (shape processing (boring)).

[0032] During this boring process, silicon is a hard, brittle material and is prone to chipping and cracking. Furthermore, because the susceptor is thin, with a thickness of 3 mm or less, careful attention is required during processing. For example, during radial drive processing, increasing the cutting depth or increasing the processing speed increases the temperature of the tool and workpiece, and heat accumulation causes thermal deformation (of both the tool and workpiece). Continuing processing while this thermal deformation persists results in significant warping.

[0033] Therefore, when forming the recess 2, the susceptor 1 is machined from its outer periphery toward its inner periphery. During this process, the susceptor 1 is rotated around its center while being machined, and warpage is suppressed by using an appropriate cutting tool angle, cutting speed, and cutting depth. When a portion of the susceptor 1 is machined in the circumferential direction, the machined portion receives a pressing force from the tool, which causes the surrounding area of ​​the machined portion to lift up. If this pressing force is too strong, circumferential waviness is likely to occur. Therefore, by gradually machining the susceptor 1 in a concentric pattern with an appropriate pressing force while rotating it, the occurrence of circumferential waviness is suppressed. It is also important to minimize the machining depth (cut depth) at one time (i.e., thin it) and minimize the heat and distortion remaining in the susceptor 1 during machining. Warpage is suppressed by reducing the machining depth and processing over a long period of time.

[0034] After shaping (boring), both sides are polished to make the surface flat with a specified thickness (flattening), after which the product is cleaned and finished, and its appearance, dimensions, etc. are inspected.

[0035] The susceptor 1 formed in this manner is held by a holding mechanism such as a robot hand, and the processing substrates (wafers) W are accommodated in the recesses 2 of its substrate mounting surface 1a, and these processing substrates W are then transported together to a plasma processing apparatus such as a plasma etching apparatus or a film forming apparatus for CVD or the like.

[0036] 4, the stage 11 on which the susceptor 1 is mounted has an electrostatic chuck 12 and a base 13 that supports the electrostatic chuck 12. The electrostatic chuck 12 has an electrode portion 14 and a dielectric layer 15 that covers the surface of the electrode portion 14, and a plurality of grooves 16 are formed on the upper surface of the dielectric layer 15. The grooves 16 are formed over the entire surface of the electrostatic chuck 12 by combining radial, annular, or other shapes. The base 13 integrally holds the electrostatic chuck 12, and has cooling water channels 17 formed therein through which a coolant flows.

[0037] A heat transfer gas supply path 18 is formed to vertically penetrate the base 13 and the electrostatic chuck 12 and communicate with the groove 16 in the dielectric layer 15. This heat transfer gas supply path 18 communicates with a part of the groove 16, and the groove 16 is formed so that the heat transfer gas supplied from the heat transfer gas supply path 18 is released radially outward while being diffused over the surface of the stage 11. In the example shown in FIG. 4 , one heat transfer gas supply path 18 is formed in the center of the stage 11, but multiple heat transfer gas supply paths 18 may be formed parallel to one another. Helium (He) gas is generally used as the heat transfer gas.

[0038] The susceptor 1, with the processing substrate W accommodated in the recess 2, is placed on the stage 11 and attracted by the electrostatic chuck 12. The susceptor 1 is made of silicon and has a low specific resistance, so it is reliably attracted by the electrostatic chuck 12. The bottom wall of the recess 2 is thin, and the processing substrate W in the recess 2 is also a silicon wafer, so that the processing substrate W also adheres to the bottom surface of the recess 2 by the attracting force of the electrostatic chuck 12.

[0039] With the susceptor 1 placed thereon, a minute space is formed between the susceptor 1 and the electrostatic chuck 12 by the grooves 16. When a heat transfer gas, such as helium gas, which has been temperature-controlled by heat exchange with the electrostatic chuck (internal heater and internal heat transfer medium liquid) is supplied into this minute space through the heat transfer gas supply path 18, the heat transfer gas passes through the grooves 16 and flows throughout the entire minute space between the susceptor 1 and the electrostatic chuck 12, exchanges heat to control the temperature of the susceptor, and is then released radially outward from the electrostatic chuck 12. In this manner, the temperature of the susceptor 1 is controlled (heated or cooled) by the heat transfer gas, and the temperature of the substrate W to be processed in the recess 2 is uniformly controlled via the susceptor 1.

[0040] In this case, the susceptor 1 is attracted to the stage 11 by an electrostatic chuck 12, and it is necessary that the lifting force of the heat transfer gas does not exceed the attracting force of the electrostatic chuck 12. Then, the required plasma processing is performed on the upper surface of the processing substrate (wafer) W.

[0041] In the above plasma processing, the susceptor 1 is made of silicon, which has high thermal conductivity, and due to this excellent thermal conductivity, the entire surface is uniformly heated by the heat transfer gas flowing through the back surface (second surface) 1b of the susceptor 1. Therefore, the processing substrate (wafer) W in the recess 2 is also uniformly heated within its surface, allowing plasma processing such as etching and film formation to be performed uniformly within its surface, making it possible to manufacture high-quality semiconductor devices.

[0042] In addition, if the susceptor 1 has a slight warp (e.g., a convex warp of 0.1 μm to 20 μm), the warp is formed so as to be convex toward the substrate-mounting surface 1 a. Therefore, when the susceptor 1 is placed on the stage 11 of the plasma processing apparatus, the concave surface of the back surface (second surface) 1 b is placed over the surface of the stage 11. As a result, a space is formed between the surface of the stage 11 and the stage 11. Grooves 16 are formed in the surface of the stage 11. The formation of this space allows the heat transfer gas supplied from the heat transfer gas supply path 18 to spread into the space through the grooves 16 and transfer heat from the space to the entire back surface 1 b of the susceptor 1. This further enhances the heat transfer effect, and the susceptor 1 is heated quickly and uniformly.

[0043] If the warp of the susceptor 1 is reversed (the substrate mounting surface 1a side is concave), an open gap is formed at the outer periphery between the susceptor 1 and the surface of the stage 11, making it difficult for the heat transfer gas to stagnate and making it difficult for heat to be transferred to the susceptor 1, which is undesirable. However, even if the warp is convex on the substrate mounting surface 1a side, if the warp is large, the processing substrate W accommodated in the recess 2 will become unstable within the recess 2, the plasma will be incident at an angle, and other undesirable effects will be exerted on the quality of the plasma processing. Therefore, the warp should be 20 μm or less, preferably 10 μm or less.

[0044] The susceptor 1 is formed of single-crystal silicon or polycrystalline silicon. Since polycrystalline silicon (e.g., columnar silicon) is composed of multiple crystals, grain boundaries exist. Therefore, when the susceptor 1 is formed of polycrystalline silicon, minute irregularities (of the order of a few micrometers) due to the grain boundaries are generated on the surface. Therefore, when the susceptor 1 is made of polycrystalline silicon, the heat transfer gas flows along the minute irregularities on the surface of the susceptor 1 on the stage 11, enabling more rapid heat transfer. Furthermore, the purity of silicon, which is the main component of the susceptor 1, is 99.99% (4N) or higher, and may be 99.9999% (6N) or higher, or 99.999999999% (11N) or higher.

[0045] The present invention is not limited to the configuration of the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, a groove for circulating a heat transfer gas may be formed on the rear surface (second surface) 1 b of the susceptor 1, and in that case, the groove 16 on the stage may be present or may be omitted.

[0046] Furthermore, through holes leading to the bottom surface of the recess 2 may be formed in the thickness direction of the susceptor 1 for the purpose of adjusting the temperature of the substrate W to be processed in the recess 2. Part of the heat transfer gas supplied from the heat transfer gas supply path 18 reaches the back surface of the substrate W to be processed in the recess 2 through the through holes, thereby enabling direct heat exchange with the substrate W to be processed, thereby improving heat transfer. In this case, too, it is necessary to ensure that the upward force of the heat transfer gas from the through holes does not exceed the suction force of the electrostatic chuck acting on the substrate W to be processed.

[0047] First, a susceptor was fabricated by forming three recesses, each 100 mm in diameter, on the first surface of a silicon disk (thickness: 2 mm, diameter: 230 mm) with a resistivity of 10 Ω cm. The following four types of susceptors were fabricated by changing the polishing method used in the flattening process.

[0048] A: The workpiece was rotated on a rotary stage while the machining tool was brought into contact with it in the circumferential direction at an appropriate machining pressure and rotation speed, thereby machining it concentrically. B: The workpiece was rotated on a rotary stage while the machining tool was brought into contact with it in the circumferential direction at a machining pressure greater than that in case A, thereby machining it. C: The workpiece was fixed on a fixed stage, and the machining tool was rotated parallel to the workpiece from above while machining it in one direction in the +X direction. D: The workpiece was fixed on a fixed stage, and the machining tool was rotated vertically to the workpiece from above while machining it in one direction in the +X direction.

[0049] For these four types of susceptors, the second surface of the susceptor was placed on a surface plate, and the heights of the central region F1 and the annular region F2 of the first surface (substrate mounting surface) were measured at multiple locations from above the first surface to grasp the shape of the first surface. As shown by M in Figure 5C, the central region F1 had nine locations including the center of the circle, the annular region F2 had eight locations, and the peripheral region F3 had eight locations.

[0050] In this measurement, the position where the recess 2 is formed may be the measurement point, in which case the measured value will be significantly different from other measured values ​​in the same area. However, by taking into consideration the size (diameter, depth) and position of the recess, it is determined whether the significantly different measured value from other measured values ​​in the same area is due to the bottom surface of the recess 2 or due to waviness, and the shape is grasped.

[0051] The results of these measurements are shown in Figure 6. The leftmost column in Figure 6 is a schematic diagram showing the height distribution of the susceptor surface shape in terms of brightness, with areas of the same brightness indicating the same height. The three columns on the right side show, from left to right, the X-direction cross section, the Y-direction cross section, and the 45° direction cross section (see Figure 5C for these cross-sectional directions). In Figure 6, the surface plate is shown as a horizontally arranged rectangle, and the susceptor is shown above it with a thick solid line. The surface shape shown in Figure 6 will be explained briefly as follows.

[0052] A: In cross sections along the X-axis, Y-axis, and any diagonal direction between them, the central region is higher, and in the annular region, the region gradually becomes lower from the center toward the periphery (curving in a dome shape convex toward the first surface). B: Stress concentration occurs in the area where the processing pressure was excessive, and the surrounding area deforms in an opposite direction, causing circumferential waviness overall, with high and low regions occurring at approximately 90° intervals. C: In cross sections along the Y-axis, the central region is curved so as to be convex, but in cross sections along the X-axis and diagonal directions, the region is deformed so as to be warped upward in one direction in the + direction. D: In cross sections along the Y-axis, the region is almost flat, but in cross sections along the X-axis and diagonal directions, the region is deformed so as to be warped upward in one direction in the + direction.

[0053] Then, for each of these four types of susceptors, a Johnson-Rahbek electrostatic chuck having a hyperbolic internal electrode was installed, and a heat transfer gas (He) was supplied to the heat transfer gas flow path at a predetermined pressure while the attraction voltage was changed, and the pressure sealing state of the susceptor was confirmed.

[0054] Those that were able to seal the heat transfer gas and did not subsequently experience any abnormal adsorption (too much static electricity built up and unable to desorb) were rated B. Those that did not adsorb in the first place, and those that were able to adsorb but not desorb, were rated C. Those that were able to seal the heat transfer gas at a pressure of 1000 Pa and were able to exchange heat were rated B, and those that were able to seal the heat transfer gas at a pressure of 2000 Pa and were able to exchange more heat were rated A. The ESC (electrostatic chuck) voltage was varied as shown in the table, and the test was carried out at a stage temperature of 40°C (the temperature of the coolant flowing through the stage). The results are shown in Table 1.

[0055]

[0056] The results in Table 1 show that susceptors A, C, and D were able to seal in the heat transfer gas at a predetermined pressure and performed well in both adsorption and desorption, regardless of whether the adsorption voltage was 250 V, 500 V, 1000 V, or 2500 V. The results were particularly good at adsorption voltages of 500 V or higher. In contrast, susceptor B was unable to adsorb at an adsorption voltage of 250 V, indicating that adsorption was difficult unless the voltage was high.

[0057] Each susceptor was placed in a plasma etching apparatus and subjected to plasma irradiation. The plasma conditions were a radio frequency (RF) power output of 300 W, an argon (Ar) gas flow rate of 100 sccm, and a pressure of 10 Pa for 60 seconds. The stage temperature was 40°C, and the susceptor surface temperature was measured using a temperature label. A bipolar Johnson-Rahbek electrostatic chuck was used, and the clamping voltage was 2500 V. The results are shown in Table 2.

[0058]

[0059] It can be seen that susceptor A is sufficiently cooled. The cooling effect decreases next for susceptors C and D, and finally for susceptor D. Only susceptor A reached a temperature of 100°C or less. When a wafer coated with a resin resist used in normal masking is placed as the processing substrate, a temperature of 100°C or less is preferable. However, a temperature of around 150°C is not expected to pose any practical problems when the processing substrate is a wafer made of a heat-resistant resin such as polyimide or an inorganic material that does not change properties due to heat.

[0060] Next, the second surface was placed on a surface plate, and the heights of the first surface 1a and the second surface 1b from the surface plate P were measured as shown in Figures 5A and 5B. The thickness of the susceptor was subtracted from the difference between the heights to measure the height distribution of the space S formed between the surface plate P and the second surface 1b. The maximum height h and the height of each of the central region F1, the annular region F2, and the peripheral region F3 were then measured, and average values ​​H1 to H3 and standard deviations were calculated for each of the regions F1 to F3. The results are shown in Table 3.

[0061]

[0062] As shown in Table 3, the average height H1 of the central region F1, the average height H2 of the annular region F2, and the average height H3 of the peripheral region F3 of susceptor A decreased in this order (H1 > H2 > H3), indicating an overall curved shape convex toward the first surface. The standard deviation was also 2.1 or less, and the variation was small. Specifically, for susceptor A, the average height H1 of the central region F1 was 12.2 μm, the average height H2 of the annular region F2 was 8.6 μm, and the average height H3 of the peripheral region F3 was 2.9 μm. If the average heights of the respective regions are H1 = H2 = H3, the shape will be flat without any curvature; however, H1 > H2 ≧ H3 or H1 ≧ H2 > H3 may also be satisfied. Furthermore, in susceptor A, the difference (|H1-H3|) between the average height H1 of the central region F1 and the average height H3 of the peripheral region F3 is 9.3 μm, and this difference may be in the range of 6 μm to 20 μm.

[0063] Similarly, for susceptor C, the average height H1 of the central region F1 decreases, followed by the average height H2 of the annular region F2 and the average height H3 of the peripheral region F3. However, the standard deviation was 9.4 in the peripheral region, showing greater variation than for susceptor A. This is thought to be due to the presence of raised areas in the peripheral region, as shown in Figure 6C. It is assumed that the standard deviation of the height measurements is preferably 7 μm or less, and more preferably 3 μm or less. For susceptors B and D, the height of the central region is large, but the average height of the peripheral region F3 is greater than that of the annular region F2, indicating that a curved shape with a convex first surface was not obtained.

[0064] Next, three recesses each having a diameter of 100 mm were formed in a plurality of silicon disks (thickness: 2 mm, diameter: 230 mm) having different resistivities. As a comparative example, a susceptor made of sintered alumina having the same shape was also produced.

[0065] First, for each of these silicon susceptors and sintered alumina susceptors, they were placed on a surface plate, and the heights of both surfaces were measured using a laser scanning device as described above (see Figures 5A and 5B). The influence of waviness of the surface plate was eliminated, and the warpage h was measured. As a result, the warpage h of the silicon susceptors was suppressed to 25 μm or less. In particular, the warpage h of susceptor A was 15 μm or less. In contrast, the warpage h of the susceptor manufactured using sintered alumina was 200 μm or more, making it impossible to measure.

[0066] Next, a susceptor was installed in each of the Coulomb-type electrostatic chuck and the Johnson-Rahbek-type electrostatic chuck, and a heat transfer gas (He) was supplied to the heat transfer gas passage at a predetermined pressure while the clamping voltage was changed to check the pressure sealing state of the susceptor. The Coulomb-type electrostatic chuck was a monopolar type with one internal electrode, and the Johnson-Rahbek-type electrostatic chuck was a bipolar type with two internal electrodes.

[0067] Those that were able to seal the heat transfer gas and did not subsequently experience any abnormal adsorption (too much static electricity accumulated to prevent desorption) were rated B. Those that did not adsorb in the first place, and those that were able to adsorb but not desorb, were rated C. Those that were able to seal the heat transfer gas at a pressure of 1000 Pa and were able to exchange heat were rated B, and those that were able to seal the heat transfer gas at a pressure of 2000 Pa and were able to exchange more heat were rated A. The ESC (electrostatic chuck) voltage was varied as shown in the table, and the test was carried out at a stage temperature of 40°C (the temperature of the coolant flowing through the stage).

[0068] Table 4 shows the results for a Coulomb-type electrostatic chuck, and Table 5 shows the results for a Johnsen-Rahbek-type electrostatic chuck. The values ​​in the silicon column indicate the specific resistance of silicon.

[0069]

[0070]

[0071] As can be seen from Tables 4 and 5, when a Coulomb-type electrostatic chuck was used, the silicon susceptor was able to seal in a heat transfer gas at a predetermined pressure and exchange heat, regardless of whether the attracting voltage was 500 V or 1000 V. When a Johnson-Rahbek-type electrostatic chuck was used, both attraction and desorption were satisfactory over a wide range of attracting voltages from 250 V to 2500 V. In contrast, the sintered alumina susceptor could not be attracted by a Coulomb-type electrostatic chuck, and even with a Johnson-Rahbek-type electrostatic chuck, it could only be attracted by a high attracting voltage (2500 V).

[0072] Next, each susceptor was placed in a plasma etching apparatus and subjected to plasma irradiation. The plasma conditions were a radio frequency (RF) power output of 300 W, an argon (Ar) gas flow rate of 100 sccm, and a pressure of 10 Pa for 60 seconds (sec). The stage temperature was 40°C, and the susceptor surface temperature was measured using a temperature label. A monopolar Coulomb-type electrostatic chuck was used for the 500 V clamping voltage, and a bipolar Johnson-Rahbek-type electrostatic chuck was used for the 2500 V clamping voltage. The results are shown in Table 6.

[0073]

[0074] The alumina susceptor experienced an abnormal temperature rise due to plasma irradiation, and after processing, it cracked due to rapid cooling. This shows that it is difficult to apply a Coulomb-type electrostatic chuck to an insulating material. In contrast, the silicon susceptor can be applied to both a Coulomb-type and a Johnson-Rahbek-type electrostatic chuck, and the temperature was appropriately controlled.

[0075] The susceptor can be appropriately installed on the stage of the plasma processing apparatus, and the entire surface of the wafer placed on the susceptor can be uniformly heated, making it possible to manufacture high-quality devices.

[0076] REFERENCE SIGNS LIST 1 susceptor 1a first surface (substrate mounting surface) 1b second surface (rear surface) 2 recess 11 stage 12 electrostatic chuck 13 base 14 electrode portion 15 dielectric layer 16 groove 17 cooling water channel 18 heat transfer gas supply channel F1 central region F2 annular region F3 peripheral region P surface plate S space portion

Claims

1. A susceptor for use in manufacturing semiconductor devices, characterized in that it is formed in the shape of a plate having a first surface and a second surface and is made of silicon.

2. A susceptor for use in manufacturing semiconductor devices according to claim 1, characterized in that the specific resistance is 10 Ω·cm or less.

3. A susceptor for manufacturing semiconductor devices according to claim 1 or 2, characterized in that the first surface is a substrate mounting surface, the second surface is placed on a surface plate and the height of the first surface is measured, and when the average value of the central heights measured at multiple locations in a circular central region within 1 / 3 of the diameter is defined as a central height average value H1, the average value of the annular region heights measured at multiple locations in an annular region outside the central region and surrounding the central region is defined as an annular region height average value H2, and the average value of the outer peripheral region heights measured at multiple locations in a region outside the annular region within 98% of the diameter, H3, H1 ≧ H2 ≧ H3.

4. A susceptor for manufacturing semiconductor devices as described in claim 3, characterized in that it is disk-shaped with a diameter of 200 mm or more and 450 mm or less and a thickness of 0.5 mm or more and 5 mm or less, and the standard deviation of each of the center height, the annular region height, and the outer peripheral region height is 7 μm or less.

5. A susceptor for manufacturing semiconductor devices as described in claim 4, characterized in that the maximum height position of the space formed between the second surface and the base plate is located on the second surface side in the central region, and its maximum height is 20 μm or less.

6. A susceptor for manufacturing semiconductor devices according to claim 3, wherein the substrate mounting surface is warped in a direction that makes the surface convex.

7. A susceptor for manufacturing semiconductor devices according to claim 3, wherein the substrate mounting surface has one or more recesses formed therein for accommodating a substrate to be processed.

Images