Aluminum nitride substrate and sample holder

Abstract

To provide a work-piece holder capable of enhancing the volume resistance of an aluminum nitride substrate.SOLUTION: A work-piece holder 10 according to the present invention comprises an aluminum nitride substrate 1 and an internal electrode 2 disposed on the aluminum nitride substrate 1. The aluminum nitride substrate 1 comprises a plurality of aluminum nitride particles 11 and aluminum oxynitride particles 12 present on the crystal grain boundaries of the aluminum nitride particles 11. Titanium 13 is dissolved in the aluminum oxynitride particles 12 in a state of a solid solution.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to Aluminum nitride substrate and This relates to a sample holder. [Background technology]

[0002] As prior art, for example, aluminum nitride sintered bodies shown in JP-A-6-128041, JP-A-11-335173, and JP-A-2020-88195 are known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-128041 [Patent Document 2] Japanese Patent Application Publication No. 11-335173 [Patent Document 3] JP 2020-88195 A Summary of the Invention

[0004] The sample holder of the present disclosure is an aluminum nitride substrate having a plurality of aluminum nitride particles and aluminum oxynitride particles located at the grain boundaries between the aluminum nitride particles. Body The aluminum oxynitride particles contain titanium as a solid solution. [Brief description of the drawings]

[0005] [Figure 1] FIG. 1 is a longitudinal sectional view showing a sample holder according to the present disclosure. [Diagram 2] 2 is a schematic diagram showing aluminum nitride particles, aluminum oxynitride particles, and titanium solid-dissolved in the aluminum oxynitride particles in the aluminum nitride substrate of the sample holder shown in FIG. 1. [Diagram 3]FIG. 13 is a schematic diagram showing aluminum nitride particles, aluminum oxynitride particles, and titanium solid-dissolved in the aluminum oxynitride particles in an aluminum nitride substrate of another example of a sample holder. [Figure 4] FIG. 13 is a schematic diagram showing aluminum nitride particles, aluminum oxynitride particles, and titanium solid-dissolved in the aluminum oxynitride particles in an aluminum nitride substrate of another example of a sample holder. [Diagram 5] FIG. 13 is a schematic diagram showing aluminum nitride particles, aluminum oxynitride particles, and titanium solid-dissolved in the aluminum oxynitride particles in an aluminum nitride substrate of another example of a sample holder. [Figure 6] FIG. 11 is a longitudinal sectional view showing another example of a sample holder. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] An example of the sample holder 10 of the present disclosure will now be described in detail with reference to the drawings.

[0007] 1 includes an aluminum nitride substrate 1 including aluminum nitride particles 11 and aluminum oxynitride particles 12, and an internal electrode 2 provided on the aluminum nitride substrate 1. Note that the term "particles" used in this disclosure refers to crystal grains having a continuous atomic arrangement.

[0008] The aluminum nitride substrate 1 is a member for holding a sample. The aluminum nitride substrate 1 may be, for example, a plate-shaped member, or may be a disk-shaped or rectangular plate-shaped member. When the aluminum nitride substrate 1 is, for example, plate-shaped, one of the main surfaces may be a wafer-mounting surface. When the aluminum nitride substrate 1 is, for example, disk-shaped, the dimensions of the aluminum nitride substrate 1 may be, for example, a diameter of 200 to 500 mm and a thickness of 1 to 15 mm.

[0009] The aluminum nitride substrate 1 includes a plurality of aluminum nitride particles 11 and aluminum oxynitride particles 12. Here, the aluminum nitride particles 11 are particles made of aluminum nitride, but may include impurities or lattice defects other than aluminum nitride. The aluminum oxynitride particles 12 are particles made of aluminum oxynitride (AlON), but may include impurities or lattice defects other than aluminum oxynitride. The abundance ratio of aluminum nitride and aluminum oxynitride in the aluminum nitride substrate 1 may be about 95% and about 5% when analyzed by X-ray diffraction (XRD: X-ray diffraction) using CuKα rays as an X-ray source, and the aluminum nitride has a peak of the (100) plane appearing near 2θ=33.2°, and the aluminum oxynitride has a main peak of the (101) plane appearing near 2θ=33.8°, for example, in the case of 27R-aluminum oxynitride.

[0010] The aluminum nitride substrate 1 has an internal electrode 2 on its surface or inside. When the sample holder 10 is used as an electrostatic chuck, the internal electrode 2 may be an electrode for electrostatic attraction. In this case, the material of the internal electrode 2 may be a metal such as platinum or tungsten. The dimensions of the internal electrode 2 are, for example, a thickness of 0.01 mm to 0.5 mm and an area of ​​30,000 mm. 2 ~190000mm 2 The internal electrode 2 may be a heating resistor. In this case, the internal electrode 2 may contain a metal component such as silver palladium, and a glass component having an oxide of a material such as silicon, bismuth, calcium, aluminum, and boron. In this case, the dimensions of the internal electrode 2 may be, for example, a thickness of 0.01 mm to 0.1 mm, a width of 0.5 mm to 5 mm, and a length of 1000 mm to 50000 mm. The aluminum nitride substrate 1 may have a plurality of internal electrodes 2. The aluminum nitride substrate 1 may have an electrostatic attraction electrode and a heater electrode 3.

[0011] The aluminum nitride substrate 1 of the present disclosure includes aluminum nitride particles 11 and aluminum oxynitride particles 12, and titanium 13 is dissolved in the aluminum oxynitride particles 12. In other words, the sample holder 10 of the present disclosure includes an aluminum nitride substrate 1 having a plurality of aluminum nitride particles 11 and aluminum oxynitride particles 12 located at the grain boundaries between the aluminum nitride particles 11, and an internal electrode 2 provided on the aluminum nitride substrate 1, and titanium 13 is dissolved in the aluminum oxynitride particles 12. This makes it possible to increase the volume resistivity of the aluminum nitride substrate 1. The reason for this will be explained below.

[0012] First, in the aluminum oxynitride particles 12 in which titanium 13 is dissolved, the defects of titanium 13 are electrically positive compared to normal aluminum oxynitride particles 12. This is because the aluminum in the aluminum oxynitride particles 12 is replaced with titanium 13, resulting in a shortage of one electron. In addition, the aluminum nitride particles 11 have aluminum vacancies, which are electrically negative. In this way, the titanium defects in the aluminum oxynitride particles 12 and the aluminum vacancies in the aluminum nitride particles 11 have opposite charges. Therefore, the aluminum oxynitride particles 12 in which titanium 13 is dissolved can electrostatically pin the aluminum vacancies present near the grain boundaries in the aluminum nitride particles 11. As a result, the volume resistivity of the aluminum nitride substrate 1 can be increased compared to when titanium 13 is not dissolved in the aluminum oxynitride particles 12.

[0013] Fig. 2 shows a schematic example of the form in which aluminum oxynitride particles 12 and aluminum nitride particles 11 exist in a substrate. In Fig. 2, the hatched regions are aluminum oxynitride particles 12, and the other regions are aluminum nitride particles 11. Moreover, what exists inside aluminum oxynitride particle 12 and is shown circled is titanium 13.

[0014] As shown in FIG. 2, the aluminum nitride substrate 1 of the present disclosure includes aluminum nitride particles 11 and aluminum oxynitride particles 12, and titanium 13 is dissolved in the aluminum oxynitride particles 12. Titanium 13 may be dissolved in the aluminum oxynitride particles 12 in a plurality of separate regions. The aluminum nitride substrate 1 may have aluminum oxynitride particles 12 in which titanium 13 is not dissolved. Titanium 13 may be present in the grain boundary between the aluminum nitride particles 11 and the aluminum oxynitride particles 12. Titanium 13 may be present in the grain boundary of the aluminum nitride particles 11. Titanium 13 may be present in the grain boundary between the aluminum oxynitride particles 12 and the aluminum oxynitride particles 12.

[0015] 3, the aluminum oxynitride particles 12 may have an elongated shape. Alternatively, the aluminum oxynitride particles 12 may exist in an elongated region in the aluminum nitride substrate 1. In this case, the aluminum oxynitride particles 12 in which titanium 13 is dissolved are present over a wide range of the grain boundaries, and therefore the aluminum oxynitride particles 12 in which titanium 13 is present can electrostatically pin more aluminum vacancies present in the grain boundaries of the aluminum nitride particles 11. As a result, the volume resistivity of the aluminum nitride substrate 1 can be further increased.

[0016] The aluminum nitride substrate 1 includes aluminum nitride particles 11 and aluminum oxynitride particles 12, and titanium 13 is dissolved in the aluminum oxynitride particles 12. This can be confirmed by structural analysis using the following method. First, a predetermined portion of the aluminum nitride substrate 1 is taken out by a known method such as cutting, cutting, or polishing. Next, the taken out portion is sliced ​​into a thin piece by a known method such as argon ion milling to obtain a sample. Then, the sample is structurally analyzed by a known method such as a transmission electron microscope (TEM), electron diffraction, energy dispersive X-ray spectroscopy (EDS), electron energy loss spectroscopy (EELS), mapping analysis, or X-ray diffraction (XRD: X-ray diffraction), to identify the aluminum oxynitride in the sintered body and the oxygen contained in the aluminum oxynitride. Next, titanium 13 in the sintered body is identified by the above method or a method such as time-of-flight secondary ion mass spectrometry (TOF-SIMS). If the distributions of oxygen and titanium 13 overlap, it can be said that titanium 13 is dissolved in the aluminum oxynitride particles 12 as a solid solution.

[0017] The aluminum oxynitride particles 12 may be located in the periphery of the internal electrode 2. This makes it possible to pin aluminum vacancies in the periphery of the internal electrode 2, thereby preventing the transfer of charge from the aluminum nitride to the internal electrode 2 when a voltage is applied. As a result, the volume resistivity of the aluminum nitride substrate 1 can be further increased. For example, the aluminum oxynitride particles 12 may be located at a position 0.01 to 1.5 mm from the surface of the internal electrode 2.

[0018] The aluminum oxynitride particles 12 may be in contact with the internal electrode 2. This allows the charge moving from the aluminum nitride substrate 1 toward the electrode when a voltage is applied to be pinned, thereby compensating for the charge. This allows the volume resistivity of the portion in contact with the internal electrode 2 to be increased. As a result, the attachment and detachment of the sample can be further improved.

[0019] Furthermore, the aluminum oxynitride particles 12 may be present in greater numbers on the internal electrode 2 side of the sample holder 1 than on the wafer-mounting surface side. This can increase the pinning effect in the region on the internal electrode 2 side compared to the region on the wafer-mounting surface side. This allows the charge transfer when power is supplied to the electrodes to be sharpened, increasing the response speed. As a result, polarization after stopping application of voltage to the electrostatic adsorption electrodes of the sample holder 1 can be reduced, making it easier to attach and detach the sample.

[0020] The "wafer mounting surface side" here means a region 0.01 to 1.5 mm from the wafer mounting surface. The "internal electrode 2 side" here means a region 0.01 to 1.5 mm from the internal electrode 2. The fact that aluminum oxynitride particles 12 are present in greater numbers on the internal electrode 2 side than on the wafer mounting surface side can be confirmed by detecting oxygen locations on the wafer mounting surface side and the internal electrode 2 side of the sample holder 1 using, for example, wavelength dispersive X-ray spectroscopy (WDS) or X-ray photoelectron spectroscopy (XPS) as an analytical device.

[0021] 4, the aluminum oxynitride particles 12 may have a portion where titanium is segregated in the portion in contact with the aluminum nitride particles 11. This makes it possible to more efficiently electrostatically pin aluminum vacancies present near the grain boundaries in the aluminum nitride particles 11. This makes it possible to further increase the volume resistivity of the aluminum nitride substrate 1.

[0022] 5, the aluminum nitride particles 11 may have a portion where titanium 13 is segregated in a portion in contact with the aluminum oxynitride particles 12. This allows titanium defects in the aluminum nitride particles 11 to electrostatically pin aluminum vacancies. This allows the volume resistivity of the aluminum nitride substrate 1 to be further increased.

[0023] The internal electrode 2 may also contain aluminum nitride. This allows compensation of electric charge between the aluminum nitride contained in the internal electrode 2 and the aluminum nitride particles 11 on the wafer holding surface side and the opposite side of the internal electrode 2. This makes it possible to reduce bias of electric charge inside the sample holder 10.

[0024] 6, the internal electrode 2 is an electrode for electrostatic attraction, and the aluminum nitride substrate 1 further includes a heater electrode 3, and may further include aluminum oxynitride particles 12 in which titanium 13 is dissolved, around the heater electrode 3. This can enhance the pinning effect at the site where the temperature is high and the generation of electric charge from the aluminum nitride particles 11 is increased. As a result, the volume resistivity of the aluminum nitride substrate 1 can be further increased. For example, the aluminum oxynitride particles 12 may be located at a position 0.01 to 1.5 mm from the surface of the heater electrode 3. The aluminum oxynitride particles 12 may be in contact with the heater electrode 3.

[0025] The manufacturing method of the aluminum nitride substrate 1 used in the sample holder 10 of the present disclosure is described below. First, aluminum nitride powder, aluminum oxide powder, titanium oxide powder, and a substance that can generate carbon when fired, such as a binder, are mixed and molded into a predetermined shape. Next, the molded body is fired at 2000°C or higher and cooled to 100°C. At this time, for example, the cooling rate can be set to 3.5 to 5.0°C per minute to achieve supercooling. At this time, 27R-aluminum oxynitride in which titanium 13 is dissolved, which would not be generated without supercooling, precipitates in the aluminum nitride sintered body. This makes it possible to obtain an aluminum nitride substrate 1 containing aluminum oxynitride particles 12 in which titanium 13 is dissolved. By the above manufacturing method, a sample 1 containing aluminum oxynitride particles 12 in which titanium 13 is dissolved was produced.

[0026] Also, sample 2 containing aluminum oxynitride particles 12 in which titanium 13 is not dissolved was prepared by a normal manufacturing method that does not involve supercooling. The volume resistivity of these was evaluated by the following method. First, a sample measuring 50 to 60 mm in length, 50 to 60 mm in width, and 0.5 to 2 mm in thickness was cut out from the aluminum nitride sintered body, washed with acid and alkali, and dried. Next, a main electrode, a ring electrode, and a counter electrode were printed and baked on this sample, and the volume resistivity was measured using the three-terminal method (JIS C 2141:1992). The results are shown in Table 1.

[0027] [Table 1]

[0028] As shown in Table 1, sample 2, which does not contain aluminum oxynitride particles 12 in which titanium 13 is dissolved, has a volume resistivity of 5×10 at 400° C. 8 In contrast, the sample 1 containing the aluminum oxynitride particles 12 in which titanium 13 is dissolved has a volume resistivity of 5×10 9 Ωcm. In this way, by including aluminum oxynitride particles 12 in which titanium 13 is dissolved, the volume resistivity of the aluminum nitride substrate 1 used in the sample holder 10 can be increased. By using such an aluminum nitride substrate 1 as the sample holder 10, polarization is eliminated after the application of voltage to the electrostatic attraction electrode is stopped, and the wafer can be easily attached and detached. [Explanation of symbols]

[0029] 1: Aluminum nitride substrate 11: Aluminum nitride particles 12: Aluminum oxynitride particles 13: Titanium 2: Internal electrode 3: Heater electrode 10: Sample holder

Claims

1. The aluminum nitride particles have a plurality of aluminum oxynitride particles located at grain boundaries between the aluminum nitride particles, An aluminum nitride substrate, characterized in that titanium is dissolved in the aluminum oxynitride particles.

2. 2. The aluminum nitride substrate according to claim 1, wherein the aluminum oxynitride particles have an elongated shape.

3. 3. The aluminum nitride substrate according to claim 2, wherein the aluminum oxynitride particle is in continuous contact with a plurality of the aluminum nitride particles.

4. 4. The aluminum nitride substrate according to claim 1, wherein the titanium is dissolved in the aluminum oxynitride grains in a state in which the titanium is separated into a plurality of regions.

5. An aluminum nitride substrate according to claim 1, further comprising aluminum oxynitride particles in which titanium is not dissolved.

6. 6. The aluminum nitride substrate according to claim 1, wherein said titanium is present at grain boundaries between said aluminum nitride grains and said aluminum oxynitride grains.

7. 7. The aluminum nitride substrate according to claim 1, wherein said titanium is present at grain boundaries of said aluminum nitride grains.

8. 8. The aluminum nitride substrate according to claim 1, wherein the titanium is present at grain boundaries between the aluminum oxynitride particles.

9. 9. The aluminum nitride substrate according to claim 1, wherein said aluminum oxynitride particles have portions in contact with said aluminum nitride particles, where titanium is segregated.

10. 10. The aluminum nitride substrate according to claim 1, wherein said aluminum nitride particles have a portion where titanium is segregated in contact with said aluminum oxynitride particles.

11. A sample holder comprising an aluminum nitride substrate according to claim 2, the aluminum nitride substrate having an electrode disposed inside the aluminum nitride substrate.

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