Semiconductor manufacturing equipment heaters

Abstract

To provide a heater for a semiconductor manufacturing device that can improve the volume resistivity of a ceramic base and can be stably manufactured.SOLUTION: A heater for a semiconductor manufacturing device according to an embodiment of the present invention includes a ceramic base and a heating element. The ceramic base includes aluminum nitride. The heating element is embedded in the ceramic base. The ceramic base includes two or more rare earth elements, and contains Yb as a rare earth element. The total content of the rare earth elements in the ceramic base is 4.5 mass% or less in terms of oxides. The content of Yb in the ceramic base is 0.3 mass% or more and 1.3 mass% or less in terms of oxides.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a heater for use in semiconductor manufacturing equipment. [Background technology]

[0002] Conventionally, in the manufacture of semiconductor devices, heaters for semiconductor manufacturing equipment are used to support and heat semiconductor substrates. A heater for semiconductor manufacturing equipment typically includes a ceramic base and a heating element embedded in the ceramic base. As such a heater for semiconductor manufacturing equipment, for example, a ceramic heater has been proposed in which the heating element contains a metal such as molybdenum (Mo) or tungsten (W) and the ceramic substrate contains 91 to 99 mass % aluminum nitride and 1 to 9 weight % rare earth element oxide (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-141163 Summary of the Invention [Problem to be solved by the invention]

[0004] It is desirable to increase the thermal conductivity of the ceramic base in heaters for semiconductor manufacturing equipment such as the ceramic heater described in Patent Document 1. Therefore, studies have been conducted to increase the thermal conductivity of the ceramic base by adding rare earth element oxides to the ceramic base. However, simply adding a large amount of rare earth element oxide to the ceramic base increases the difference between the linear expansion coefficient of the ceramic base and the linear expansion coefficient of the heating element, which may cause damage such as cracks in the ceramic base during the production of heaters for semiconductor manufacturing equipment. Thus, there is room for improvement in achieving both an improvement in the volume resistivity of the ceramic base and the manufacturing stability of heaters for semiconductor manufacturing equipment. A primary object of the present invention is to provide a heater for semiconductor manufacturing equipment that can improve the volume resistivity of the ceramic substrate and can be manufactured stably. [Means for solving the problem]

[0005] [1] A heater for semiconductor manufacturing equipment according to an embodiment of the present invention includes a ceramic base and a heating element. The ceramic base includes aluminum nitride. The heating element is embedded in the ceramic base. The ceramic base includes two or more rare earth elements, and contains Yb as a rare earth element. The total content of rare earth elements in the ceramic base is 4.5 mass% or less in terms of oxides. The content of Yb in the ceramic base is 0.3 mass% or less in terms of oxides. End It is 1.3 mass % or less. [2] In the heater for semiconductor manufacturing equipment described in [1] above, the volume resistivity of the ceramic base at 500°C is 1×10 9 It may be Ω·cm or more. [3] In the heater for semiconductor manufacturing equipment according to the above [1] or [2], the ceramic base may further contain Y as the rare earth element. [4] In the heater for semiconductor manufacturing equipment according to any one of [1] to [3] above, the content of Ca in the ceramic base may be 300 ppm or less. [5] In the heater for semiconductor manufacturing equipment according to any one of [1] to [4] above, the content of Ca in the ceramic base may be 80 ppm or more. [6] In the heater for semiconductor manufacturing equipment according to any one of [1] to [5] above, the ceramic base may further contain Ca and Si. In this case, the mass ratio of Si to Ca in the ceramic base may be 0.060 or more and 0.20 or less. The mass ratio of Yb to Y in the ceramic base may be 0.10 or more and 0.45 or less. [Effects of the Invention]

[0006] According to the embodiments of the present invention, it is possible to improve the volume resistivity of the ceramic base and realize a heater for semiconductor manufacturing equipment that can be stably manufactured. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram of a heater for use in semiconductor manufacturing equipment according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments. In addition, in order to clarify the explanation, the width, thickness, shape, etc. of each part may be shown schematically in the drawings compared to the embodiments, but this is merely an example and does not limit the interpretation of the present invention.

[0009] A. Overview of heaters for semiconductor manufacturing equipment 1 is a schematic cross-sectional view of a heater for a semiconductor manufacturing apparatus according to one embodiment of the present invention. A heater 100 for a semiconductor manufacturing apparatus according to one embodiment of the present invention is typically capable of supporting and heating a semiconductor substrate 8.

[0010] The heater 100 for semiconductor manufacturing equipment includes a ceramic base 1 and a heating element 2. The ceramic base 1 contains aluminum nitride (AlN) as a main component. The ceramic base 1 contains two or more rare earth elements, and contains Yb as a rare earth element. The total content of rare earth elements in the ceramic base 1 is 4.5 mass % or less in terms of oxide. The content of Yb in the ceramic base 1 is 0.3 mass % or more and 1.3 mass % or less in terms of oxide. The heating element 2 is embedded in the ceramic base 1. According to this configuration, the total content of rare earth elements in the ceramic base is 4.5 mass% or less, so the difference in linear expansion coefficient between the ceramic base and the heating element can be stably reduced. Furthermore, since the ceramic base contains 0.3 mass% to 1.3 mass% of Yb among the two or more rare earth elements, the volume resistivity of the ceramic base can be sufficiently increased. Furthermore, when the content of Yb in the ceramic base is within this range, color unevenness in the ceramic base can be sufficiently suppressed. Therefore, heaters for semiconductor manufacturing equipment having ceramic substrates with excellent volume resistivity can be manufactured stably.

[0011] The total content of rare earth elements in the ceramic base 1 is, for example, 0.5 mass % or more, preferably 1.0 mass % or more, and more preferably 3.0 mass % or more, calculated as oxides. When the total content of rare earth elements in the ceramic base is within this range, the volume resistivity of the ceramic base can be stably increased. The content of each component in the ceramic substrate is measured by, for example, inductively coupled plasma atomic emission spectroscopy (ICP-AES).

[0012] The content of Yb in the ceramic base 1 is, for example, 0.3 mass % or more, preferably 0.6 mass % or more, and more preferably 0.9 mass % or more, calculated as oxide. When the content of Yb in the ceramic base is within this range, color unevenness of the ceramic base can be stably suppressed, and the volume resistivity of the ceramic base can be more stably increased.

[0013] In one embodiment, the ceramic base 1 further contains Y as a rare earth element. When the ceramic base contains both Yb and Y, it is possible to stably achieve both an improvement in the volume resistivity of the ceramic base and an improvement in the manufacturing stability of the heater for semiconductor manufacturing equipment. The Y content in the ceramic base 1 is, in terms of oxide, for example, 2.0 mass % or more, preferably 2.5 mass % or more. On the other hand, the Y content in the ceramic base 1 is, for example, 4.0 mass % or less, or for example, 3.5 mass % or less. The mass ratio of Yb to Y (Yb:Y) in the ceramic base 1 is, for example, 1:2 to 1:10, preferably 1:2 to 1:7.5, and more preferably 1:2 to 1:5. In the ceramic base 1, the mass ratio of Yb to Y (Yb / Y) is, for example, 0.08 or more, preferably 0.10 or more, more preferably 0.13 or more, even more preferably 0.20 or more, particularly preferably 0.25 or more, and particularly preferably 0.30 or more. On the other hand, in the ceramic base 1, the mass ratio of Yb to Y (Yb / Y) is, for example, 0.50 or less, preferably 0.45 or less, and more preferably 0.43 or less. When the mass ratio of Yb to Y is within this range, the volume resistivity of the ceramic base can be stably increased.

[0014] The ceramic substrate 1 may further contain other rare earth elements in addition to Yb and Y, or may contain only Yb and Y as rare earth elements. In one embodiment, the ceramic base 1 contains only Yb and Y as rare earth elements, and contains substantially no other rare earth elements. The content of the other rare earth elements in the ceramic base 1 is, for example, 0.5 mass% or less in terms of oxide. This makes it possible to more stably achieve both an improvement in the volume resistivity of the ceramic base and an improvement in the manufacturing stability of the heater for semiconductor manufacturing equipment. Examples of other rare earth elements include Ce.

[0015] The AlN content in the ceramic base 1 is, for example, 90.0 mass % or more, preferably 93.0 mass % or more, while the AlN content in the ceramic base 1 is, for example, 99.0 mass % or less, preferably 95.0 mass % or less.

[0016] The ceramic base 1 may further contain trace components in addition to AlN and rare earth elements. Examples of trace components include O, C, Ti, Ca, Mg, Si, and Fe. The trace components may be contained in the ceramic base alone or in combination of two or more. The content of trace components in the ceramic base 1 is, for example, 0.1 mass % or less, and preferably 0.05 mass % or less. In particular, the Ca content in the ceramic base 1 is, for example, 300 ppm or less, preferably 280 ppm or less, and more preferably 230 ppm or less. When the Ca content in the ceramic base is equal to or less than this upper limit, the volume resistivity of the ceramic base can be stably improved. On the other hand, the content of Ca in the ceramic base 1 is, for example, 0 ppm or more, preferably 30 ppm or more, more preferably 80 ppm or more, even more preferably 120 ppm or more, particularly preferably 140 ppm or more, and particularly preferably 200 ppm or more. When the ceramic base contains Yb and Ca in the above-mentioned proportions, the volume resistivity of the ceramic base can be significantly increased.

[0017] In one embodiment, the ceramic substrate 1 contains Ca and Si in addition to AlN and a rare earth element. The Si content in the ceramic base 1 is, for example, 40 ppm or less, preferably 30 ppm or less, and more preferably 25 ppm or less. On the other hand, the Si content in the ceramic base 1 is, for example, 0 ppm or more, preferably 5 ppm or more, and more preferably 10 ppm or more. In the ceramic base 1, the mass ratio of Si to Ca (Si / Ca) is, for example, 0.400 or less, preferably 0.300 or less, more preferably 0.200 or less, even more preferably 0.157 or less, and particularly preferably 0.100 or less. When the ceramic base contains Yb in the above ratio and Si / Ca is not more than such an upper limit, the volume resistivity of the ceramic base can be more significantly increased. On the other hand, in the ceramic base 1, the mass ratio of Si to Ca (Si / Ca) is, for example, 0.030 or more, preferably 0.050 or more, more preferably 0.060 or more, and even more preferably 0.065 or more.

[0018] Such a ceramic base 1 has a relatively high volume resistivity. The volume resistivity of the ceramic substrate 1 at 500°C is, for example, 5.0 × 10 8 Ω·cm or more, preferably 1.0×10 9 Ω·cm or more, preferably 5.0×10 9 Ω·cm or more, more preferably 7.5×10 9 On the other hand, the upper limit of the volume resistivity of the ceramic substrate 1 at 500°C is typically 1.0×10 10 The volume resistivity at 500°C is measured in accordance with JIS C2141-1992, for example.

[0019] The thermal conductivity of the ceramic base 1 at 500° C. is, for example, 60 W / m·K to 90 W / m·K, and preferably 70 W / m·K to 80 W / m·K. The thermal conductivity of the ceramic base at 500° C. is measured in accordance with, for example, JIS R1611.

[0020] The average linear expansion coefficient of the ceramic base 1 in the temperature range of 50° C. to 1000° C. is, for example, 5.3 ppm / ° C. to 5.9 ppm / ° C., and preferably 5.5 ppm / ° C. to 5.8 ppm / ° C. The average linear expansion coefficient is measured in accordance with, for example, JIS R1618.

[0021] The heating element 2 includes any suitable metal, such as tantalum (Ta), tungsten (W), molybdenum (Mo), tungsten carbide (WC), titanium nitride (TiN), platinum (Pt), rhenium (Re), hafnium (Hf), and alloys thereof. Of the metals, W, Mo, and W-Mo alloys are preferred. When the heating element contains such a metal, the coefficient of linear expansion of the ceramic base and the coefficient of linear expansion of the heating element can be stably made close to each other, thereby further improving the manufacturing stability of heaters for semiconductor manufacturing equipment.

[0022] The average linear expansion coefficient of the heating element 2 in the temperature range of 50°C to 1000°C is, for example, 5.4 ppm / °C to 6.0 ppm / °C, and preferably 5.6 ppm / °C to 5.9 ppm / °C. In addition, the ceramic substrate 1 in the temperature range of 50°C to 1000°C and The absolute value of the difference in the average linear expansion coefficient between the ceramic substrate 1 and the heating element 2 is, for example, 0.5 ppm / °C or less, and preferably 0.3 ppm / °C or less. and The lower limit of the absolute value of the difference in the average linear expansion coefficient from the heating body 2 is typically 0.1 ppm / °C.

[0023] B. Details of heaters for semiconductor manufacturing equipment Each component of the heater for semiconductor manufacturing equipment will be described in detail below.

[0024] B-1. Ceramic substrate The ceramic base 1 can have any appropriate shape depending on the application of the heater for semiconductor manufacturing equipment. A typical shape of the ceramic base 1 is a plate shape. The ceramic base 1 preferably has a disk shape. The ceramic base 1 typically has a mounting surface 1a on which a semiconductor substrate 8 can be placed. The mounting surface 1a is one surface of the ceramic base 1 in the thickness direction. The ceramic base 1 has a thickness of, for example, 10 mm to 40 mm.

[0025] As described above, the ceramic substrate 1 contains AlN as a main component and two or more rare earth elements including Yb as sub-components. Typically, the ceramic substrate 1 contains an AlN crystal phase and an ytterbium aluminate crystal phase.

[0026] In one embodiment, the AlN crystal phase has a polycrystalline structure in which a plurality of AlN crystal grains are bonded to one another. The average grain size of the plurality of AlN crystal grains is, for example, 2 μm to 5 μm, and preferably 3 μm to 4.5 μm. The ytterbium aluminate crystal phase typically exists at the grain boundaries between AlN grains.

[0027] When the rare earth element includes yttrium (Y) in addition to Yb, the ceramic substrate 1 further includes an yttrium aluminate crystalline phase, which typically exists at the grain boundaries between AlN grains.

[0028] The ceramic substrate 1 may further contain other crystal phases in addition to the AlN crystal phase, the ytterbium aluminate crystal phase, and the yttrium aluminate crystal phase, or may be substantially free of other crystal phases. In one embodiment, the ceramic substrate 1 contains only an AlN crystal phase, an ytterbium aluminate crystal phase, and an yttrium aluminate crystal phase as crystal phases, and is substantially free of other crystal phases.

[0029] The porosity of the ceramic base 1 is, for example, 1% or less. The porosity is measured in accordance with, for example, JIS R1634.

[0030] The relative density of the ceramic base 1 is, for example, 3.2 g / cc to 3.4 g / cc, and preferably 3.25 g / cc to 3.35 g / cc. The relative density of the ceramic base is the bulk density relative to the theoretical density of the ceramic base. The bulk density of the ceramic base is measured, for example, in accordance with JIS R1634.

[0031] In the illustrated example, the ceramic base 1 is supported by a ceramic shaft 5. The ceramic shaft 5 is connected to the surface of the ceramic base 1 opposite to the mounting surface 1a.

[0032] The ceramic shaft 5 has any appropriate shape. In one embodiment, the ceramic shaft 5 has a cylindrical shape extending in the thickness direction of the ceramic base 1. In the illustrated example, the axis of the ceramic shaft 5 and the center of the ceramic base 1 substantially coincide with each other when viewed in the thickness direction of the ceramic base 1. The ceramic shaft 5 is made of any appropriate ceramic material, but from the viewpoint of matching the thermal expansion difference with the ceramic base, a ceramic shaft containing the same material as the ceramic base, i.e., aluminum nitride, is preferred.

[0033] B-2. Heating element The heating element 2 is configured to generate heat when a voltage is applied. There is no particular limitation on the number of heating elements 2 embedded in the ceramic base 1. A plurality of heating elements 2 may be embedded in the ceramic base 1. In this case, the plurality of heating elements 2 are positioned apart from one another in the thickness direction of the ceramic base 1. In the illustrated example, one heating element 2 is embedded in the ceramic substrate 1 .

[0034] The heating element 2 has any appropriate shape. Examples of the heating element 2 include a coil shape, a zigzag shape, and a mesh shape. The dimension (wire diameter) of the heating element 2 in the thickness direction of the ceramic base 1 is, for example, 0.3 mm to 1.0 mm, and preferably 0.4 mm to 0.7 mm.

[0035] The volume resistivity of the heating element 2 at 500°C is, for example, 1.9 × 10 -5 Ω·cm or less, preferably 1.8×10 -5 On the other hand, the lower limit of the volume resistivity of the heating element 2 at 500°C is typically 1.6×10 -5 Ω·cm.

[0036] In the illustrated example, a first power supply rod 6 is electrically connected to the heating element 2. A voltage can be applied to the heating element 2 via the first power supply rod 6. The first power supply rod 6 is made of any appropriate conductive material. The first power supply rod 6 passes through the internal space of the ceramic shaft 5 and is electrically connected to the heating element 2.

[0037] B-3. ​​Internal electrode In one embodiment, the heater 100 for semiconductor manufacturing equipment further includes an internal electrode 3. The internal electrode 3 is embedded in the ceramic base 1. In the illustrated example, the internal electrode 3 is located between the mounting surface 1a and the heating element 2 in the thickness direction of the ceramic base 1.

[0038] The internal electrode 3 typically functions as an ESC electrode. When the internal electrode 3 functions as the ESC electrode, when a DC voltage is applied to the internal electrode 3 with the semiconductor substrate 8 mounted on the mounting surface 1a, the internal electrode 3 is charged with either positive or negative charges in accordance with the polarity of the applied DC voltage, and the other of the positive and negative charges present in the semiconductor substrate 8 moves toward the mounting surface 1a in the semiconductor substrate 8. As a result, a Johnsen-Rahbek (JR) force is generated between the semiconductor substrate 8 and the internal electrode 3, and the semiconductor substrate 8 is chucked to the ceramic base 1. Although not shown, the heater 100 for semiconductor manufacturing equipment may include a plurality of internal electrodes 3.

[0039] In one embodiment, the internal electrode 3 functions as an RF electrode (i.e., a radio frequency electrode) for plasma processing. That is, the internal electrode 3 preferably functions as an RF / ESC electrode. Examples of plasma processing include film formation processing and etching processing. When such plasma processing is performed on the semiconductor substrate 8 on the mounting surface 1a, an upper electrode is disposed on the opposite side of the semiconductor substrate 8 from the internal electrode 3. When high-frequency power is supplied to the internal electrode 3 in this state, the processing gas is excited in the space between the ceramic base 1 and the upper electrode, and plasma can be generated. The semiconductor substrate 8 is subjected to plasma processing by the plasma.

[0040] The internal electrode 3 may have any appropriate shape. The internal electrode 3 typically has a plate shape. In one embodiment, the internal electrode 3 has a shape similar to the outer shape of the ceramic base 1 when viewed in the thickness direction of the ceramic base 1. In the illustrated example, the center of the internal electrode 3 and the center of the ceramic base 1 substantially coincide with each other when viewed in the thickness direction of the ceramic base 1. The thickness of the internal electrode 3 is, for example, 0.2 mm to 0.8 mm.

[0041] The internal electrode 3 typically contains the same metal as the heating element 2 described above. Therefore, the range of the average linear expansion coefficient of the internal electrode 3 in the temperature range of 50°C to 1000°C is, for example, the same as the range of the average linear expansion coefficient of the heating element 2 described above. Furthermore, the range of the absolute value of the difference in the average linear expansion coefficient between the ceramic base 1 and the internal electrode 3 in the temperature range of 50°C to 1000°C is, for example, the same as the range of the absolute value of the difference in the average linear expansion coefficient between the ceramic base 1 and the heating element 2 described above. This makes it possible to suppress damage such as cracks in the ceramic base during the manufacture of the heater for semiconductor manufacturing equipment, even if the heater for semiconductor manufacturing equipment includes an internal electrode.

[0042] In the illustrated example, a second power feed rod 7 is electrically connected to the internal electrode 3. The above-mentioned voltage (or high-frequency power) can be applied to the internal electrode 3 via the second power feed rod 7. The second power feed rod 7 is typically made of the same metal as the internal electrode 3. The second power feed rod 7 passes through the internal space of the ceramic shaft 5 and is electrically connected to the internal electrode 3.

[0043] C. Manufacturing method of heater for semiconductor manufacturing equipment Next, a method for manufacturing a heater for semiconductor manufacturing equipment according to one embodiment will be described. A manufacturing method for a heater for semiconductor manufacturing equipment according to one embodiment includes a mixing step of mixing raw material powders for a ceramic base; a molding step of preparing a molded body having an embedded heating element from the raw material mixture obtained in the mixing step and the heating element; and a firing step of firing the molded body obtained in the molding step.

[0044] C-1.Mixing process In the mixing step, AlN powder and two or more rare earth element powders are mixed to prepare a mixed powder. In one embodiment, AlN powder, Yb2O3 powder, and Y2O3 powder are mixed to prepare a raw material mixture. The AlN powder and / or rare earth element powder may contain the above-mentioned minor components, which may be added separately to the raw material mixture as required.

[0045] The amount of Yb2O3 powder added is, for example, 0.05 parts by mass or more, preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 0.8 parts by mass or more, relative to 100 parts by mass of AlN powder. On the other hand, the upper limit of the amount of Yb2O3 powder added is typically 1.3 parts by mass relative to 100 parts by mass of AlN powder.

[0046] The amount of Y2O3 powder added is, for example, 0.5 parts by mass or more, preferably 1.0 part by mass or more, and more preferably 3.0 parts by mass or more, per 100 parts by mass of AlN powder. On the other hand, the upper limit of the amount of Y2O3 added is typically 4.3 parts by mass per 100 parts by mass of AlN powder.

[0047] In the mixing step, any appropriate mixing device can be used, for example, a ball mill, a bead mill, or a vibration mill, and preferably a ball mill.

[0048] The mixing method in the mixing step may be dry mixing or wet mixing. In one embodiment, dry mixing is performed in the mixing step.

[0049] The environmental conditions in the mixing step are not particularly limited, and the mixing step is typically carried out at room temperature (25°C) and atmospheric pressure (0.1 MPa). The duration of the mixing step is set arbitrarily and appropriately, for example, 1 hour to 30 hours.

[0050] As a result of the above, a raw material mixture containing AlN powder and two or more rare earth element powders (typically YbO powder and YO powder) is prepared. If the mixing process is dry mixing, the raw material mixture is in a powder state, and if the mixing process is wet mixing, the raw material mixture is in a slurry state.

[0051] The raw material mixture is granulated as needed, for example, by a spray dryer. This prepares a granulated product (raw material granules) of the raw material mixture.

[0052] C-2. Molding process Next, in the molding step, the raw material mixture is molded by any appropriate molding method in a state where the heating element 2 prepared in advance is embedded in the raw material mixture at a desired position. Examples of the molding method include press molding, sheet molding, and cold isostatic pressing (CIP) molding, and press molding is preferred. The pressure in press molding is, for example, 10 kgf / cm. 2 ~500kgf / cm 2 is. In this way, a molded body having a desired shape is prepared.

[0053] C-3. Firing process In the firing step, the molded body is fired by any suitable firing method. Typically, the molded body is fired in a vacuum or a non-oxidizing atmosphere. For example, the temperature is raised from room temperature (23°C) to a predetermined firing temperature, and then the firing temperature is maintained for a predetermined firing time.

[0054] The firing temperature is, for example, 1600° C. to 1900° C., and preferably 1650° C. to 1850° C. The firing time is, for example, 0.5 hours to 20 hours.

[0055] Examples of the firing method include hot pressing and hot isostatic pressing (HIP), with hot pressing being preferred. In the hot press, typically, the compact is placed in a hot press die (for example, a graphite die), heated to the firing temperature as described above, and pressed at a predetermined pressure, for example, 5 MPa to 50 MPa.

[0056] In this manner, a heater for semiconductor manufacturing equipment is manufactured, which includes a ceramic base and a heating element embedded in the ceramic base. [Example]

[0057] The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to these examples. The methods for measuring each property are as follows.

[0058] (1) Measurement of the average linear expansion coefficient of the ceramic substrate and the heating element The average linear expansion coefficients of the ceramic base and heating element included in the heaters for semiconductor manufacturing equipment manufactured in the examples and comparative examples were measured in accordance with JIS R 1618. Table 1 shows the average linear expansion coefficients of the ceramic base and heating element, as well as the difference between the average linear expansion coefficients.

[0059] (2) Measurement of volume resistivity of ceramic substrate The volume resistivity of the ceramic substrates provided in the heaters for semiconductor manufacturing equipment manufactured in the examples and comparative examples was measured in accordance with JIS C2141. The results are shown in Table 1.

[0060] <<Example 1>> 95 parts by mass of AlN powder, 3 parts by mass of Y2O3 powder, and 1.3 parts by mass of Yb2O3 powder were placed in a ball mill and dry mixed for 10 hours. This produced a mixed powder (raw material mixture). The mixed powder was then granulated by spray drying.

[0061] Also, a coil-shaped heating element made of Mo was prepared. Next, the granules of the mixed powder were filled into a predetermined mold, and the heating element was embedded in a desired position. The mixed powder granules filled in the mold were then subjected to uniaxial pressing to obtain a disk-shaped compact. The pressure in the uniaxial pressing was 100 kgf / cm. 2 The diameter of the molded body was 350 mm, and the thickness of the molded body was 50 mm.

[0062] The compact was then sintered by hot pressing. More specifically, the compact was placed in a hot pressing die made of graphite and sintered at 1850°C for 5 hours by hot pressing. The pressure of the hot pressing was 10 MPa. In this way, a heater for semiconductor manufacturing equipment comprising a ceramic base and a heating element was manufactured. After that, the heater for semiconductor manufacturing equipment was cooled to room temperature (25° C.). The ceramic substrate contained trace amounts of Ca and Si in addition to AlN, Yb, and Y. yttrium The respective contents of Yb (ytterbium), the total content of rare earth elements, and the content of trace elements are shown in Table 1 below.

[0063] <<Example 2>> A heater for semiconductor manufacturing equipment was manufactured in the same manner as in Example 1, except that the amount of Y2O3 powder was changed to 3.5 parts by mass, the amount of Yb2O3 powder was changed to 0.9 parts by mass, and the content ratios of trace elements (Ca and Si) were adjusted to the values ​​shown in Table 1. yttrium The respective contents of Yb (ytterbium), the total content of rare earth elements, and the content of trace elements are shown in Table 1 below.

[0064] <<Example 3>> A heater for semiconductor manufacturing equipment was manufactured in the same manner as in Example 1, except that the amount of Yb2O3 powder was changed to 0.6 parts by mass and the content ratio of trace elements (Ca and Si) was adjusted to the values ​​shown in Table 1. yttrium The respective contents of Yb (ytterbium), the total content of rare earth elements, and the content of trace elements are shown in Table 1 below.

[0065] <<Example 4>> A heater for semiconductor manufacturing equipment was manufactured in the same manner as in Example 1, except that the amount of Yb2O3 powder was changed to 0.4 parts by mass and the content ratio of trace elements (Ca and Si) was adjusted to the values ​​shown in Table 1. yttrium The respective contents of Yb (ytterbium), the total content of rare earth elements, and the content of trace elements are shown in Table 1 below.

[0066] <<Example 5>> A heater for semiconductor manufacturing equipment was manufactured in the same manner as in Example 1, except that the amount of Y2O3 powder was changed to 2.0 parts by mass, the amount of Yb2O3 powder was changed to 0.6 parts by mass, and the content ratios of trace elements (Ca and Si) were adjusted to the values ​​shown in Table 1. yttrium The respective contents of Yb (ytterbium), the total content of rare earth elements, and the content of trace elements are shown in Table 1 below.

[0067] <<Example 6>> A heater for semiconductor manufacturing equipment was manufactured in the same manner as in Example 1, except that the amount of Y2O3 powder was changed to 2.9 parts by mass, the amount of Yb2O3 powder was changed to 0.3 parts by mass, and the content ratios of trace elements (Ca and Si) were adjusted to the values ​​shown in Table 1. yttrium The respective contents of Yb (ytterbium), the total content of rare earth elements, and the content of trace elements are shown in Table 1 below.

[0068] <<Example 7>> A heater for semiconductor manufacturing equipment was manufactured in the same manner as in Example 5, except that the amount of Yb2O3 powder was changed to 1.0 part by mass and the content ratio of trace elements (Ca and Si) was adjusted to the values ​​shown in Table 1. yttrium The respective contents of Yb (ytterbium), the total content of rare earth elements, and the content of trace elements are shown in Table 1 below.

[0069] <<Example 8>> A heater for semiconductor manufacturing equipment was manufactured in the same manner as in Example 1, except that the amount of Yb2O3 powder was changed to 1.0 part by mass and the content ratio of trace elements (Ca and Si) was adjusted to the values ​​shown in Table 1. yttrium The respective contents of Yb (ytterbium), the total content of rare earth elements, and the content of trace elements are shown in Table 1 below.

[0070] <<Comparative Example 1>> A heater for semiconductor manufacturing equipment was manufactured in the same manner as in Example 1, except that the mixed powder was prepared by mixing 96 parts by mass of AlN powder and 4 parts by mass of Y2O3 powder, and the content ratios of trace elements (Ca and Si) were adjusted to the values ​​shown in Table 1. Y ( yttrium The respective contents of Yb (ytterbium), the total content of rare earth elements, and the content of trace elements are shown in Table 1 below.

[0071] <<Comparative Example 2>> A heater for semiconductor manufacturing equipment was manufactured in the same manner as in Example 1, except that the mixed powder was prepared by mixing 96 parts by mass of AlN powder and 4 parts by mass of Yb2O3 powder, and the content ratios of trace elements (Ca and Si) were adjusted to the values ​​shown in Table 1. Y ( yttrium The respective contents of Yb (ytterbium), the total content of rare earth elements, and the content of trace elements are shown in Table 1 below.

[0072] <<Comparative Example 3>> A heater for semiconductor manufacturing equipment was manufactured in the same manner as in Example 1, except that the mixed powder was prepared by mixing 95 parts by mass of AlN powder, 3.0 parts by mass of Y2O3 powder, and 0.2 parts by mass of Yb2O3 powder, and the content ratios of trace elements (Ca and Si) were adjusted to the values ​​shown in Table 1. Y ( yttrium The respective contents of Yb (ytterbium), the total content of rare earth elements, and the content of trace elements are shown in Table 1 below.

[0073] <<Comparative Example 4>> A heater for semiconductor manufacturing equipment was manufactured in the same manner as in Example 1, except that the mixed powder was prepared by mixing 96 parts by mass of AlN powder, 2.6 parts by mass of Y2O3 powder, and 1.5 parts by mass of Yb2O3 powder, and the content ratios of trace elements (Ca and Si) were adjusted to the values ​​shown in Table 1. Y ( yttrium The respective contents of Yb (ytterbium), the total content of rare earth elements, and the content of trace elements are shown in Table 1 below.

[0074] [Table 1] <Evaluation> Table 1 shows the relationship between the volume resistivity of the ceramic base at 500°C and the appearance of the ceramic base. In Examples 1 to 8, the volume resistivity of the ceramic base was improved and color unevenness of the ceramic base was sufficiently suppressed (appearance OK). Therefore, it is clear that heaters for semiconductor manufacturing equipment with excellent volume resistivity can be stably manufactured. In Comparative Examples 2 and 4, although the volume resistivity of the ceramic substrate was relatively high, the color unevenness was significant and the products were unsuitable (appearance NG). [Industrial Applicability]

[0075] A heater for semiconductor manufacturing equipment according to an embodiment of the present invention is typically used in the manufacture of semiconductors, and can be suitably used in particular as a ceramic heater for holding and heating semiconductor substrates. [Explanation of symbols]

[0076] 1. Ceramic substrate 2 heating elements 100 Heater for semiconductor manufacturing equipment

Claims

1. a ceramic substrate containing aluminum nitride; a heating element embedded in the ceramic substrate, The thickness of the ceramic substrate is 10 mm to 40 mm, the ceramic substrate contains two or more rare earth elements and Ca, and also contains Yb as a rare earth element; the total content of rare earth elements in the ceramic substrate is 4.5 mass% or less in terms of oxides; The content of Yb in the ceramic base is 0.3 mass % or more and 1.3 mass % or less in terms of oxide, A heater for semiconductor manufacturing equipment, wherein the content of Ca in the ceramic base is 80 ppm or more and 300 ppm or less.

2. The volume resistivity of the ceramic substrate at 500°C is 1×10 ９ 2. The heater for semiconductor manufacturing equipment according to claim 1, wherein the resistivity is Ω·cm or more.

3. 3. The heater for semiconductor manufacturing equipment according to claim 1, wherein said ceramic substrate contains Y as said rare earth element.

4. A ceramic substrate containing aluminum nitride; a heating element embedded in the ceramic substrate, the ceramic substrate contains two or more rare earth elements, Ca and Si, and also contains Yb as a rare earth element; the total content of rare earth elements in the ceramic substrate is 4.5 mass% or less in terms of oxides; The content of Yb in the ceramic base is 0.3 mass % or more and 1.3 mass % or less in terms of oxide, a mass ratio of Si to Ca in the ceramic base is 0.060 or more and 0.20 or less; A heater for semiconductor manufacturing equipment, wherein the mass ratio of Yb to Y in the ceramic base is 0.10 or more and 0.45 or less.

Images