Heaters for AlN ceramic matrix and semiconductor manufacturing equipment

Abstract

The AlN ceramic matrix of the present invention is an AlN ceramic matrix containing yttrium aluminate, which has a volume resistivity of 3 × 10⁻⁶ at 550 °C. 9 Ωcm or more.

Description

Technical Field

[0001] This invention relates to AlN ceramic substrates and heaters for semiconductor manufacturing apparatus. Background Technology

[0002] As a heater for semiconductor manufacturing apparatus, as shown in Patent Document 1, a heater comprising an AlN ceramic substrate and a resistive heating element embedded within the AlN ceramic substrate is known. Such a heater for semiconductor manufacturing apparatus is used to heat a wafer placed on the surface of an AlN ceramic substrate. Furthermore, as shown in Patent Document 2, a heater for semiconductor manufacturing apparatus is also known that has a resistive heating element and an electrostatic electrode embedded within an AlN ceramic substrate. In such a heater for semiconductor manufacturing apparatus, the wafer can be damaged when current leaks from the resistive heating element to the wafer or from the electrostatic electrode to the wafer. Therefore, it is preferable to control the volume resistivity of the AlN ceramic substrate to a high value. In view of this, Patent Document 3 discloses an AlN ceramic substrate obtained by granulating a mixed powder of AlN raw material powder to which yttrium oxide powder as a sintering aid is added, forming a disc-shaped molded body from the granules, and hot-pressing the molded body at 1850–1890°C. The volume resistivity of this AlN ceramic substrate at 550°C is 1 × 10⁻⁶. 9 ~2.6×10 9 The high value of Ωcm.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2008-153194

[0006] Patent Document 2: Japanese Patent Application Publication No. 2005-281046

[0007] Patent Document 3: Japanese Patent No. 6393006 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] However, the volume resistivity at 550℃ is 1×10⁻⁶. 9 ~2.6×10 9 In the case of AlN ceramic matrix with a strength of Ωcm, it is sometimes impossible to adequately prevent leakage current from flowing in the AlN ceramic matrix.

[0010] This invention was made to solve such a problem, and its main objective is to provide an AlN ceramic matrix with a higher volume resistivity at high temperatures than before.

[0011] Solution for solving the problem

[0012] The AlN ceramic matrix of the present invention is an AlN ceramic matrix containing yttrium aluminate, which has a volume resistivity of 3 × 10⁻⁶ at 550 °C. 9 Ωcm or more.

[0013] This AlN ceramic substrate exhibits a higher volume resistivity at high temperatures than previously possible. Therefore, when using this AlN ceramic substrate as an AlN ceramic substrate for embedding a resistive heating element in a heater for a semiconductor manufacturing apparatus, leakage current flow within the AlN ceramic substrate can be effectively prevented.

[0014] It should be noted that if the volume resistivity is 5×10 9 If the volume resistivity is above Ωcm, leakage current can be further suppressed. Therefore, it is preferable if the volume resistivity is 1×10⁻⁶. 10 If the thickness is above Ωcm, the thickness of the ceramic matrix can be further reduced, which is therefore preferred. In addition, examples of yttrium aluminate include Y4Al2O9 (YAM) and YAlO3 (YAL).

[0015] In the AlN ceramic matrix of the present invention, the average particle size of the AlN sintered particles is preferably 1.5 μm or more and 2.5 μm or less, and yttrium aluminate is preferably dispersed at the grain boundaries between the AlN sintered particles. This results in a fine and uniform dispersion of yttrium aluminate. Therefore, current paths for yttrium aluminate formation are prevented, and the volume resistivity of the AlN ceramic matrix at high temperatures is improved.

[0016] The heater for the semiconductor manufacturing apparatus of the present invention is formed by embedding a resistive heating element in the above-mentioned AlN ceramic substrate.

[0017] In the heater used in this semiconductor manufacturing apparatus, the AlN ceramic substrate exhibits a higher volume resistivity at high temperatures than before. Therefore, it is possible to effectively prevent leakage current from flowing through the AlN ceramic substrate.

[0018] In the heater for a semiconductor manufacturing apparatus of the present invention, the resistive heating element is preferably made of Mo. In the AlN ceramic substrate, a first annular layer surrounding the resistive heating element and a second annular layer surrounding the first annular layer are preferably present in contact with the resistive heating element. Compared to the second annular layer, the first annular layer has a higher Y content and a wider layer width. The first annular layer may continuously surround the resistive heating element, and the second annular layer may continuously surround the first annular layer. The second annular layer may also have a shape with an interruption in a portion of the annular shape, and may be a shape that, if the interrupted portions are imaginarily connected, forms a complete loop. Furthermore, the average value of the Y content per unit width distributed along the width direction of the first annular layer may be higher than the average value of the Y content per unit width distributed along the width direction of the second annular layer. Attached Figure Description

[0019] [ Figure 1 Top view of heater 10 for semiconductor manufacturing apparatus.

[0020] [ Figure 2 ] Figure 1 AA sectional view.

[0021] [ Figure 3 Cross-sectional view of a modified example of the second annular layer L2.

[0022] [ Figure 4 [SEM image of the Mo-containing cross section of the AlN ceramic sintered body 12 of Example 1.]

[0023] [ Figure 5 [Schematic diagram of the cross section containing Mo of the AlN ceramic sintered body 12 in Example 1.]

[0024] [ Figure 6 The graph represents the results of the EPMA analysis performed in Example 1.

[0025] [ Figure 7 [SEM image of the Mo-containing cross section of the AlN ceramic sintered body of Comparative Example 1.]

[0026] [ Figure 8 A schematic diagram of the cross-section containing Mo of the AlN ceramic sintered body of Comparative Example 1.

[0027] [ Figure 9 The graph represents the results of the EPMA analysis performed on Comparative Example 1. Detailed Implementation

[0028] Hereinafter, a heater 10 for a semiconductor manufacturing apparatus, which is a preferred embodiment of the present invention, will be described. Figure 1This is a top view of the heater 10 for a semiconductor manufacturing apparatus. Figure 2 yes Figure 1 A cross-sectional view (AA). It should be noted that... Figure 1 A single-dotted line indicates the boundary of a region. Additionally, in Figure 1 In the figure, the inner peripheral resistive heating element 30 and the outer peripheral resistive heating element 40 are represented by hidden lines (dashed lines), but the RF electrode 20 is omitted.

[0029] The heater 10 for a semiconductor manufacturing apparatus is formed by embedding an RF electrode 20, an inner peripheral resistive heating element 30, and an outer peripheral resistive heating element 40 in a disc-shaped AlN ceramic substrate 12.

[0030] The AlN ceramic substrate 12 contains yttrium aluminate (e.g., YAL, YAM), and a wafer mounting surface 12a is formed on its upper surface. The AlN ceramic substrate 12 has a volume resistivity of 3 × 10⁻⁶ at 550 °C. 9 Ωcm or more, preferably 5×10 9 Ωcm or more, more preferably 1×10 10 Above Ωcm. When viewed from above, the AlN ceramic substrate 12 is divided into an inner peripheral region Zin and an outer peripheral region Zout. The inner peripheral region Zin is a circular region with a diameter smaller than that of the AlN ceramic substrate 12. The outer peripheral region Zout is an annular region surrounding the inner peripheral region Zin.

[0031] The RF electrode 20 is a circular metal mesh (e.g., a Mo coil) arranged substantially parallel to the wafer mounting surface 12a. The RF electrode 20 is embedded closer to the wafer mounting surface 12a than the inner peripheral resistive heating element 30 and the outer peripheral resistive heating element 40. The diameter of the RF electrode 20 is slightly smaller than the diameter of the AlN ceramic substrate 12. A high-frequency voltage is applied between the RF electrode 20 and parallel planar electrodes (not shown) spaced apart from the wafer mounting surface 12a. The RF electrode 20 is connected to an RF connection member 22. The upper end of the RF connection member 22 is connected to the lower surface of the RF electrode 20, and the lower end protrudes from the lower surface 12b of the AlN ceramic substrate 12. The RF connection member 22 is arranged to pass through the gaps in the wiring pattern of the inner peripheral resistive heating element 30. The RF connection member 22 is used when a high-frequency voltage is applied between the RF electrode 20 and the parallel planar electrodes.

[0032] The inner peripheral resistive heating element 30 is a metal coil (e.g., a Mo coil) and is disposed substantially parallel to the wafer mounting surface 12a. The inner peripheral resistive heating element 30 is configured such that, starting from one of a pair of terminals 32, 34 located near the center of the AlN ceramic substrate 12, wiring is performed in a single, non-intersecting manner throughout the entire inner peripheral region Zin, reaching the other side of the pair of terminals 32, 34. The pair of terminals 32, 34 are connected to a pair of inner peripheral connecting members 36, 38. The lower ends of the pair of inner peripheral connecting members 36, 38 protrude from the lower surface 12b of the AlN ceramic substrate 12. When the inner peripheral resistive heating element 30 is heated, a voltage is applied between the pair of terminals 32, 34 using the pair of inner peripheral connecting members 36, 38.

[0033] The peripheral resistive heating element 40 is a metal coil (e.g., a Mo coil) and is disposed substantially parallel to the wafer mounting surface 12a. The peripheral resistive heating element 40 is configured as follows: starting from one of a pair of terminals 42, 44 located near the center of the AlN ceramic substrate 12, it extends through the inner peripheral region Zin to the outer peripheral region Zout, and then, following a single-stroke, non-intersecting wiring pattern, it continues through the entire outer peripheral region Zout, before returning to the inner peripheral region Zin to reach the other of the pair of terminals 42, 44. The pair of terminals 42, 44 are connected to a pair of peripheral connecting members 46, 48. The lower ends of the pair of peripheral connecting members 46, 48 protrude from the lower surface 12b of the AlN ceramic substrate 12. When the peripheral resistive heating element 40 is heated, a voltage is applied between the pair of terminals 42, 44 using the pair of peripheral connecting members 46, 48. The peripheral resistive heating element 40 and the inner peripheral resistive heating element 30 are disposed on the same plane.

[0034] Next, an example of using the heater 10 for a semiconductor manufacturing apparatus will be described. First, the heater 10 for a semiconductor manufacturing apparatus is placed in a chamber (not shown). Then, a wafer W is placed on the wafer mounting surface 12a of the heater 10, and an external power supply is connected to the connection parts 36 and 38 of the inner peripheral resistive heating element 30, applying a voltage between a pair of terminals 32 and 34. Simultaneously, another external power supply is connected to the connection parts 46 and 48 of the outer peripheral resistive heating element 40, applying a voltage between a pair of terminals 42 and 44. As a result, the inner peripheral resistive heating element 30 and the outer peripheral resistive heating element 40 heat up, heating the wafer W to a predetermined temperature. In this embodiment, the inner peripheral region Zin and the outer peripheral region Zout can be individually temperature controlled. In this state, a high-frequency voltage is applied between the parallel planar electrode (not shown) and the RF electrode 20, which are separately arranged above the wafer W, to perform various processes required for manufacturing a semiconductor chip on the wafer W. After processing, the application of high-frequency voltage to RF electrode 20 and voltage application to inner peripheral resistive heating element 30 and outer peripheral resistive heating element 40 are stopped, and wafer W is removed from wafer mounting surface 12a.

[0035] Next, a manufacturing example of the heater 10 for the semiconductor manufacturing apparatus will be described. First, AlN raw material powder is prepared. The AlN raw material powder may contain small amounts of O, C, Ti, and Ca. Preferably, the AlN raw material powder contains 0.65 to 0.90% by mass of O, 220 to 380 ppm by mass of C, 95 ppm by mass or less of Ti, and 250 ppm by mass or less of Ca. The average particle size of the AlN raw material powder is preferably set such that the average particle size of the sintered AlN particles after firing is 1.5 μm or more and 2.5 μm or less, for example, preferably 1.5 μm or more and 2.0 μm or less.

[0036] Next, Y2O3 powder, as a sintering aid, is added to the prepared AlN raw material powder and mixed to form a mixed powder, which is then granulated by spray drying. Y2O3 is added at a rate of 4–6% by mass relative to the total mixed powder. The average particle size of the Y2O3 powder is preferably in the submicron range. As a mixing method, wet mixing using organic solvents can be employed, or dry mixing, as exemplified by ball mills, vibratory mills, or dry bag mixing, can be used.

[0037] Next, using particles of the mixed powder, an RF electrode 20, an inner peripheral heating element 30, and an outer peripheral resistive heating element 40 are embedded internally and shaped to form a molded body. Then, an AlN sintered body is formed by firing the molded body. Thus, a heater 10 for a semiconductor manufacturing apparatus is obtained. The firing method can be, for example, hot pressing. The maximum temperature (firing temperature) during hot pressing is preferably set between 1650°C and 1750°C, and preferably between 1670°C and 1730°C. The holding time at the firing temperature is preferably set to 0.5 to 100 hours, the pressing pressure is preferably set to 5 to 50 MPa, and the atmosphere is preferably a nitrogen atmosphere or a vacuum atmosphere (e.g., 0.13 to 133.3 Pa). During hot pressing, it is preferable to perform at least one operation holding for at least 1 hour during the period before reaching the maximum temperature (from 1500°C to a temperature 10°C lower than the maximum temperature).

[0038] When observing the SEM image obtained by photographing the cross-section of the AlN ceramic substrate 12 of the heater 10 for the semiconductor manufacturing apparatus, the average particle size of the AlN sintered particles is preferably 1.5 μm or more and 2.5 μm or less, and yttrium aluminate, which is finer than the AlN sintered particles, is dispersed at the grain boundaries between the AlN sintered particles. If the average particle size of the AlN sintered particles is greater than the above-mentioned average particle size, yttrium aluminate exists in a state of wetting the grain boundaries between the AlN sintered particles, which easily forms a current path, and therefore the volume resistivity at high temperature does not become sufficiently high. Conversely, if the average particle size of the AlN sintered particles is 1.5 μm or more and 2.5 μm or less, yttrium aluminate exists in a state of dispersion at the grain boundaries between the AlN sintered particles, and therefore no current path is formed, and the volume resistivity at high temperature becomes sufficiently high.

[0039] Furthermore, when Mo is used in both the inner peripheral resistive heating element 30 and the outer peripheral resistive heating element 40, in the AlN ceramic substrate 12, such as Figure 2 As shown in the enlarged view, a first annular layer L1 continuously (i.e., uninterruptedly) surrounds the inner peripheral resistive heating element 30, in connection with it, and a second annular layer L2 continuously surrounds the first annular layer L1. Compared to the second annular layer L2, the first annular layer L1 has a higher Y content and a wider layer width. That is, the first annular layer L1 is a Y-rich layer, and the second annular layer L2 is a Y-poor layer. This microstructure can also be observed around the periphery of the outer peripheral resistive heating element 40. The reason for considering the first annular layer L1 to be a Y-rich layer is as follows.

[0040] If the firing temperature exceeds 1750℃, the Y concentration in the region in contact with the Mo-made inner peripheral resistive heating element 30 decreases. It is believed that if the firing temperature exceeds 1750℃, Mo, due to its high affinity for oxygen, seeks to remove oxygen from the yttrium aluminate surrounding Mo. Conversely, the yttrium aluminate surrounding Mo does not want to have oxygen removed and therefore moves away from Mo. Thus, it is believed that if the firing temperature exceeds 1750℃, the Y concentration in the region of the AlN ceramic matrix 12 in contact with the Mo-made inner peripheral resistive heating element 30 decreases. This is believed to be one reason why the volume resistivity does not become sufficiently high at high temperatures.

[0041] On the other hand, if the firing temperature is between 1650°C and 1750°C, the γ concentration in the region (first annular layer L1) in contact with the Mo-made inner peripheral resistive heating element 30 becomes relatively high. It is believed that if the firing temperature is below 1750°C, the reaction in which Mo abstracts oxygen from the surrounding yttrium aluminate is unlikely to occur, thus the yttrium aluminate around Mo does not easily migrate away from Mo. Therefore, it is believed that if the firing temperature is between 1650°C and 1750°C, the γ concentration in the region (first annular layer L1) in the AlN ceramic matrix 12 in contact with the Mo-made inner peripheral resistive heating element 30 does not decrease but becomes a γ-rich layer. This is believed to be one reason why the volume resistivity becomes sufficiently high at high temperatures.

[0042] According to the above description, the volume resistivity of the AlN ceramic substrate 12 in the heater 10 for the semiconductor manufacturing apparatus of this embodiment is 3 × 10⁻⁶. 9 The resistance is above Ωcm, which is higher than before. Therefore, it can effectively prevent leakage current from flowing in the AlN ceramic matrix 12. It should be noted that if the volume resistivity is 5×10⁻⁶... 9 If the volume resistivity is above Ωcm, leakage current can be further suppressed. Therefore, it is preferable if the volume resistivity is 1×10⁻⁶. 10 If the thickness is above Ωcm, the thickness of the ceramic matrix can be further reduced, which is therefore preferred.

[0043] Furthermore, the average particle size of the AlN sintered particles in the AlN ceramic matrix 12 is preferably 1.5 μm or more and 2.5 μm or less, and yttrium aluminate is preferably dispersed at the grain boundaries between the AlN sintered particles. This results in a fine and uniform dispersion of yttrium aluminate. Therefore, current paths for yttrium aluminate formation can be prevented, and the volume resistivity of the AlN ceramic matrix 12 at high temperatures can be improved.

[0044] Furthermore, the inner peripheral resistive heating element 30 and the outer peripheral resistive heating element 40 are preferably made of Mo. Preferably, a first annular layer L1 and a second annular layer L2 continuously surround the inner peripheral resistive heating element 30 and the outer peripheral resistive heating element 40 in the AlN ceramic matrix 12, in a manner connected to the inner peripheral resistive heating element 30 and the outer peripheral resistive heating element 40. Compared to the second annular layer L2, the first annular layer L1 has a higher Y content and a wider layer width. This structure is believed to contribute to the high volume resistivity at high temperatures. Such a structure is easily achieved by performing at least one operation, holding the temperature for at least one hour during the period before reaching the maximum temperature (from 1500°C to a temperature 10°C lower than the maximum temperature), during hot pressing.

[0045] Furthermore, the heater 10 for a semiconductor manufacturing apparatus is obtained as follows: an RF electrode 20, an inner peripheral resistive heating element 30, and an outer peripheral resistive heating element 40 are embedded in a mixed powder of AlN powder and Y2O3 powder (the Y2O3 powder constitutes 4% to 6% by mass of the total mixed powder) and molded to obtain a molded body. Then, the maximum firing temperature is set to 1650°C or higher and 1750°C or lower, and the molded body is hot-pressed and fired. Therefore, it is relatively easy to manufacture a heater 10 for a semiconductor manufacturing apparatus that can sufficiently prevent leakage current from flowing in the AlN ceramic substrate 12.

[0046] It should be noted that the present invention is not limited to any of the above embodiments. As long as it falls within the technical scope of the present invention, it can be implemented in various ways.

[0047] For example, in the above embodiment, an RF electrode 20 is embedded in the AlN ceramic substrate 12. However, the RF electrode 20 may be omitted, replaced by an electrostatic electrode, or used as an electrostatic electrode. When an electrostatic electrode is provided, the wafer W can be adsorbed and held on the wafer mounting surface 12a by applying a voltage to the electrostatic electrode.

[0048] In the above embodiments, a metal mesh is exemplified as the RF electrode 20, but a metal plate may also be used. Additionally, a metal coil is exemplified as the inner peripheral resistive heating element 30 and the outer peripheral resistive heating element 40, but a metal strip or metal mesh may also be used. Furthermore, the RF electrode 20, the inner peripheral heating element 30, and the outer peripheral resistive heating element 40 may also be formed by printing conductive paste into a predetermined shape or pattern.

[0049] In the above embodiment, an inner peripheral resistive heating element 30 is embedded in the inner peripheral region Zin, and an outer peripheral resistive heating element 40 is embedded in the outer peripheral region Zout. However, the AlN ceramic substrate 12 can also be divided into three or more regions, and a resistive heating element can be embedded in each region. Alternatively, the AlN ceramic substrate 12 can be wired throughout the entire substrate without dividing it into multiple regions.

[0050] In the above embodiments, the inner peripheral resistive heating element 30 and the outer peripheral resistive heating element 40 are embedded on the same plane, but they can also be embedded on different planes.

[0051] In the above embodiments, a heater 10 for a semiconductor manufacturing apparatus is exemplified. However, it is also possible to fabricate the AlN ceramic substrate 12 separately without embedding the RF electrode 20, the inner peripheral resistive heating element 30, and the outer peripheral resistive heating element 40 in the AlN ceramic substrate 12.

[0052] In the above embodiment, the second annular layer L2 is formed to continuously surround the first annular layer L1, but it is not particularly limited to this. For example, as Figure 3 As shown, the second annular layer L2 may not be continuous, but rather have a shape with interrupted portions L2a in a portion of the annulus. The second annular layer L2 forms a loop (a complete loop) when the interrupted portions L2a are imaginarily connected.

[0053] Example

[0054] The following describes embodiments of the present invention. It should be noted that the following embodiments do not limit the present invention in any way.

[0055] [Example 1]

[0056] First, AlN raw material powder is prepared. 5% by mass of Y₂O₃ powder is added to this AlN raw material powder as a sintering aid, and the mixture is prepared by ball milling to form a mixed powder. This mixed powder is then granulated by spray drying. Y₂O₃ is added at 5% by mass relative to the total mixed powder. Next, a disc-shaped molded body is formed using the granules of the mixed powder. An RF electrode 20, an inner peripheral resistive heating element 30, and an outer peripheral resistive heating element 40 are embedded in the molded body. Then, a heater 10 for a semiconductor manufacturing apparatus is fabricated by hot-pressing the molded body. During hot-pressing, the maximum firing temperature (firing temperature) is set to 1720°C, the holding time at the firing temperature is set to 2 hours, the pressing pressure is set to 20 MPa, and the atmosphere is a nitrogen atmosphere. It should be noted that during hot-pressing, during the period before reaching the maximum temperature (from 1500°C to a temperature 10°C lower than the maximum temperature), at least two holding times of 1 hour are performed.

[0057] The crystalline phases contained in the AlN ceramic matrix 12 were identified by X-ray diffraction. X-ray diffraction was performed using a Bruker AXS D8 ADVANCE sample of approximately 0.5 g of powder. The measurement conditions were a CuK α-ray source, a tube voltage of 40 kV, and a tube current of 40 mA. The results were analyzed using Rietveld analysis to identify and quantify the crystalline phases. The crystalline phases identified by the XRD pattern were AlN, YAM, and YAL; TiN was not identified.

[0058] [Comparative Example 1]

[0059] Except for setting the maximum temperature to 1850°C and not maintaining it during the period before reaching the maximum temperature, the heater for the semiconductor manufacturing apparatus was manufactured in the same manner as in Example 1. In Comparative Example 1, the crystalline phases identified by XRD patterns were AlN, YAM, and YAL, but TiN was not identified.

[0060] [Volume Resistivity]

[0061] For the heater 10 of the semiconductor manufacturing apparatus in Example 1, the volume resistivity of the AlN ceramic substrate 12 at 550°C was measured. The measurement was performed as follows: A Si wafer W was placed on the wafer mounting surface 12a, and the leakage current (the current flowing between the wafer W and the RF electrode 20) was measured when a voltage was applied between the wafer W and the RF electrode 20 (metal mesh) at 550°C. The diameter of the RF electrode 20 was... The dielectric layer (the layer between the wafer mounting surface 12a and the RF electrode 20) has a thickness of 1.02 mm, and an applied voltage of 660 V. Multiple heaters 10 for semiconductor manufacturing apparatus of Example 1 were fabricated, and the leakage current was measured, with results in the range of 40 mA. The volume resistivity of the AlN ceramic substrate 12 at 550 °C was indirectly calculated based on the leakage current, and the average value was 1.2 × 10⁻⁶. 10 Ωcm. On the other hand, for Comparative Example 1, the leakage current was measured in the same manner as in Example 1, and the result was in the range of 280 mA. The average volume resistivity of the AlN ceramic matrix at 550 °C was 2.4 × 10⁻⁶. 9 Ωcm.

[0062] [Microstructure]

[0063] The average particle size of the AlN sintered particles was determined from the SEM image of the Mo-containing cross-section of the AlN ceramic sintered body 12 of Example 1, and the result was 1.9 μm. Therefore, in Example 1, it was determined that yttrium aluminate was uniformly dispersed at the grain boundaries between the fine AlN sintered particles. The average particle size of Comparative Example 1 was also determined in the same way, and the result was 4.5 μm, which is larger than that of Example 1. It should be noted that, regarding the average particle size, a secondary electron image (3000x magnification) was obtained, a straight line was drawn on the image, and the length of the line segment crossing 40 particles was measured and used as their average value.

[0064] Figure 4 The image is a SEM image obtained by photographing a cross-section of the AlN ceramic sintered body 12 of Example 1, which includes Mo (inner peripheral side resistive heating element 30). Figure 5 This is its schematic diagram. (By...) Figure 4 and Figure 5 It can be observed that a first annular layer L1 continuously (without interruption) surrounds Mo in a manner connected to Mo, and a second annular layer L2 continuously surrounds the first annular layer L1. The first annular layer L1 has more scattered white and fine spots (from Y in yttrium aluminate), but the second annular layer L2 has almost no such spots and is basically black. Figure 6 It means along Figure 4 The arrows indicate the direction of the EPMA analysis results for Mo and Y, respectively. (In...) Figure 6 In this study, the regions where the Mo concentration rises sharply and the regions where it falls sharply are considered the boundaries between the resistive heating element (Mo) and the AlN ceramic sintered body. The first annular layer L1 has a relatively high Y concentration, but the second annular layer L2 has an almost zero Y concentration. Therefore, the first annular layer L1 is a Y-rich layer, and the second annular layer L2 is a Y-poor layer. In addition, the layer width of the first annular layer L1 is wider than that of the second annular layer L2.

[0065] Figure 7 The image is a SEM image obtained by photographing a Mo-containing cross-section of the AlN ceramic sintered body of Comparative Example 1. Figure 8 This is its schematic diagram. (By...) Figure 7 and Figure 8 It can be observed that a first layer surrounds Mo in a manner that connects to Mo, and a second layer surrounds the first layer. The first layer is a nearly black layer with almost no spots, while the second layer has more spots. The second layer is discontinuous. [The text continues with further details about the second layer and its discontinuity.] Figure 7 The results of EPMA analysis performed on Mo and Y, respectively, in the direction of the arrows are shown in the figure. Figure 9 .exist Figure 9In this study, the regions where the Mo concentration increases sharply and decreases sharply are considered the boundaries between the resistive heating element (Mo) and the AlN sintered body. The Y concentration in the first layer is almost zero, while the Y concentration in the second layer is relatively high. Therefore, it can be seen that the first layer of Comparative Example 1 is a Y-depleted layer, and the second layer is a Y-rich layer, which is the opposite of Example 1.

[0066] This application is based on the priority claim of Japanese Patent Application No. 2021-44405, filed on March 18, 2021, the entire contents of which are incorporated herein by reference.

[0067] Industrial availability

[0068] This invention can be used in heaters for semiconductor manufacturing equipment.

[0069] Symbol Explanation

[0070] 10: Heater for semiconductor manufacturing apparatus; 12: AlN ceramic substrate; 12a: Wafer mounting surface; 12b: Lower surface; 20: RF electrode; 22: RF connection component; 30: Inner peripheral resistive heating element; 32, 34: Terminals; 36, 38: Inner peripheral connection component; 40: Outer peripheral resistive heating element; 42, 44: Terminals; 46, 48: Outer peripheral connection component; L1: First annular layer; L2: Second annular layer; W: Wafer; Zin: Inner peripheral region; Zout: Outer peripheral region.

Claims

1. A heater for a semiconductor manufacturing apparatus, wherein a resistive heating element is embedded in an AlN ceramic substrate. The AlN ceramic matrix contains yttrium aluminate, and the volume resistivity of the AlN ceramic matrix at 550°C is 3 × 10⁻⁶. 9 Ωcm or more, The resistive heating element is made of Mo. In the AlN ceramic matrix, there is a first annular layer surrounding the resistive heating element in contact with the resistive heating element and a second annular layer surrounding the first annular layer. Compared with the second annular layer, the first annular layer has a higher content of Y (yttrium) and a wider layer width.

2. The heater for a semiconductor manufacturing apparatus according to claim 1, wherein, In the AlN ceramic matrix, the average particle size of the AlN sintered particles is greater than 1.5 μm and less than 2.5 μm. Yttrium aluminate exists as a dispersion at the grain boundaries between AlN sintered particles.

3. The heater for a semiconductor manufacturing apparatus according to claim 1 or 2, wherein, The first annular layer continuously surrounds the resistive heating element. The second annular layer continuously surrounds the first annular layer.

Images