Heater for semiconductor manufacturing apparatus

Abstract

The invention provides a heater for a semiconductor manufacturing device, which can improve the volume resistivity of a ceramic substrate and can be stably manufactured. A heater for a semiconductor manufacturing apparatus according to an embodiment of the present invention is provided with a ceramic base and a heating element. The ceramic matrix includes aluminum nitride. The heating body is implanted into the ceramic base body. The ceramic matrix 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 matrix is 4.5 mass% or less in terms of oxides. The content ratio of Yb in the ceramic matrix is from 0.3% by mass to 1.3% by mass (inclusive) in terms of oxides.

Description

TECHNICAL FIELD The present application relates to a semiconductor manufacturing apparatus heater. BACKGROUND Conventionally, in the production of semiconductor devices, a semiconductor manufacturing apparatus heater that supports and heats a semiconductor substrate is used. Typically, the semiconductor manufacturing apparatus heater has a ceramic base and a heating element implanted in the ceramic base. As such a semiconductor manufacturing apparatus heater, for example, a ceramic heater is proposed in which the heating element contains a metal such as molybdenum (Mo) or tungsten (W), and the ceramic base contains 91 to 99 mass% of aluminum nitride and 1 to 9 mass% of a rare earth element oxide (see Patent Document 1). PRIOR ART DOCUMENTS PATENT DOCUMENTS Patent Document 1: Japanese Patent Application Publication No. 2002-141163 SUMMARY In the semiconductor manufacturing apparatus heater like the ceramic heater described in Patent Document 1, it is desirable to increase the thermal conductivity of the ceramic base. Therefore, it has been investigated to add a rare earth element oxide to the ceramic base to increase the thermal conductivity of the ceramic base. However, if a large amount of a rare earth element oxide is simply added to the ceramic base, the difference between the linear expansion coefficient of the ceramic base and the linear expansion coefficient of the heating element becomes large, and in the production of the semiconductor manufacturing apparatus heater, there is a possibility that cracking or the like occurs in the ceramic base, and there is room for improvement in terms of simultaneously achieving an increase in the volume resistivity of the ceramic base and the production stability of the semiconductor manufacturing apparatus heater. The present application has been made in view of the above circumstances, and it is an object of the present application to provide a semiconductor manufacturing apparatus heater that can increase the volume resistivity of a ceramic base and can be stably produced.

[0001] The semiconductor manufacturing apparatus heater according to an embodiment of the present application has a ceramic base and a heating element. The ceramic base contains aluminum nitride. The heating element is implanted in the ceramic base. The ceramic base contains two or more kinds of rare earth elements, and contains Yb as a rare earth element. The total content ratio of the rare earth elements in the ceramic base is 4.5 mass% or less on an oxide basis. The content ratio of Yb in the ceramic base is 0.3 mass% or more and 1.3 mass% or less on an oxide basis.

[0002] The semiconductor manufacturing apparatus heater according to the above [1], in which the volume resistivity of the ceramic base at 500°C can be 1 x 10 9 Ω·cm or more.

[0003] The semiconductor manufacturing apparatus heater according to the above [1] or [2], in which in the ceramic base, Y can be further contained as the rare earth element.

[0004] The semiconductor manufacturing apparatus heater according to any one of [1] to [3] above can have a Ca content ratio in the ceramic base of 300 ppm or less.

[0005] The semiconductor manufacturing apparatus heater according to any one of [1] to [4] above can have a Ca content ratio in the ceramic base of 80 ppm or more.

[0006] The semiconductor manufacturing apparatus heater according to any one of [1] to [5] above can further include Ca and Si in the ceramic base. In this case, a mass ratio of Si to Ca in the ceramic base can be 0.060 or more and 0.20 or less. A mass ratio of Yb to Y in the ceramic base can be 0.10 or more and 0.45 or less. Effects of Invention According to the embodiment of the present application, a semiconductor manufacturing apparatus heater that can improve the volume resistivity of the ceramic base and can be stably manufactured can be achieved. BRIEF DESCRIPTION OF DRAWINGS Figure 1 is a schematic configuration diagram of a semiconductor manufacturing apparatus heater according to an embodiment of the present application. Explanation of Symbols 1...ceramic base, 2...heating element, 100...semiconductor manufacturing apparatus heater. DETAILED DESCRIPTION Hereinafter, embodiments of the present application will be described, but the present application is not limited to these embodiments. Also, in order to make the description more clear, the drawings sometimes schematically represent the width, thickness, shape, and the like of each part compared to the embodiments, but this is only an example and does not limit the explanation of the present application. A. Overview of Semiconductor Manufacturing Apparatus Heater Figure 1 is a schematic cross-sectional view of a semiconductor manufacturing apparatus heater according to an embodiment of the present application. Typically, the semiconductor manufacturing apparatus heater 100 according to an embodiment of the present application can support and heat a semiconductor substrate 8. The semiconductor manufacturing apparatus heater 100 has a ceramic base 1 and a heating element 2. The ceramic base 1 includes aluminum nitride (AIN) as a main component. The ceramic base 1 includes two or more rare earth elements, and includes Yb as a rare earth element. The total content ratio of the rare earth elements in the ceramic base 1 is 4.5 mass% or less in terms of oxide. Also, the content ratio 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 implanted in the ceramic base 1. According to such a configuration, the total content ratio of the rare earth elements in the ceramic base is 4.5% by mass or less, and thus the difference in the linear expansion coefficient between the ceramic base and the heat generating body can be stably reduced. In addition, the content ratio of Yb among the two or more kinds of rare earth elements in the ceramic base is 0.3% by mass or more and 1.3% by mass or less, and thus the volume resistivity of the ceramic base can be sufficiently increased. In addition, if the content ratio of Yb in the ceramic base is within such a range, the color unevenness in the ceramic base can be sufficiently suppressed. Thus, a semiconductor manufacturing apparatus heater having a ceramic base with excellent volume resistivity can be stably manufactured. The total content ratio of the rare earth elements in the ceramic base 1 is, for example, 0.5% by mass or more, preferably 1.0% by mass or more, and more preferably 3.0% by mass or more, in terms of oxides. If the total content ratio of the rare earth elements in the ceramic base is within such a range, the volume resistivity of the ceramic base can be stably increased. Note that the content ratio of each component in the ceramic base is measured, for example, by an inductively coupled plasma atomic emission spectrometry (ICP-AES). The content ratio of Yb in the ceramic base 1 is, for example, 0.3% by mass or more, preferably 0.6% by mass or more, and more preferably 0.9% by mass or more, in terms of oxides. If the content ratio of Yb in the ceramic base is within such a range, the color unevenness in the ceramic base can be stably suppressed, and the volume resistivity of the ceramic base can be more stably increased. In one embodiment, in the ceramic base 1, Y is further included as a rare earth element. If Yb and Y are both contained in the ceramic base, the increase in the volume resistivity of the ceramic base and the increase in the manufacturing stability of the semiconductor manufacturing apparatus heater can be stably achieved at the same time. The content ratio of Y in the ceramic base 1 is, for example, 2.0% by mass or more, and preferably 2.5% by mass or more, in terms of oxides. On the other hand, the content ratio of Y in the ceramic base 1 is, for example, 4.0% by mass or less, and for example, 3.5% by 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, further preferably 0.20 or more, particularly preferably 0.25 or more, and especially 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. If the mass ratio of Yb to Y is in such a range, the volume resistivity of the ceramic substrate can be stably increased. The ceramic substrate 1 can contain other rare earth elements in addition to Yb and Y, and can contain only Yb and Y as the rare earth elements. In one embodiment, the ceramic substrate 1 contains only Yb and Y as the rare earth elements and substantially does not contain other rare earth elements. The content ratio of the other rare earth elements in the ceramic substrate 1 is, for example, 0.5% by mass or less as converted into an oxide. Thus, the increase in the volume resistivity of the ceramic substrate and the increase in the manufacturing stability of the heater for a semiconductor manufacturing apparatus can be more stably achieved at the same time. Note that Ce and the like can be given as the other rare earth elements. The content ratio of AlN in the ceramic substrate 1 is, for example, 90.0% by mass or more, and preferably 93.0% by mass or more. On the other hand, the content ratio of AlN in the ceramic substrate 1 is, for example, 99.0% by mass or less, and preferably 95.0% by mass or less. The ceramic substrate 1 can contain trace components in addition to AlN and the rare earth elements. As the trace components, for example, O, C, Ti, Ca, Mg, Si, and Fe can be given. The trace components can be contained in the ceramic substrate alone or in combination with two or more kinds. The content ratio of the trace components in the ceramic substrate 1 is, for example, 0.1% by mass or less, and preferably 0.05% by mass or less. In particular, the content ratio of Ca in the ceramic substrate 1 is, for example, 300 ppm or less, preferably 280 ppm or less, and more preferably 230 ppm or less. If the content ratio of Ca in the ceramic substrate is the upper limit or less, the volume resistivity of the ceramic substrate can be stably provided. On the other hand, the content ratio of Ca in the ceramic substrate 1 is, for example, 0 ppm or more, preferably 30 ppm or more, more preferably 80 ppm or more, further preferably 120 ppm or more, particularly preferably 140 ppm or more, and especially preferably 200 ppm or more. If the ceramic substrate contains Yb and Ca in the above ratios, respectively, the volume resistivity of the ceramic substrate can be significantly increased. In one embodiment, the ceramic substrate 1 contains Ca and Si in addition to AlN and the rare earth elements. The content ratio of Si in the ceramic substrate 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 content ratio of Si in the ceramic substrate 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, further preferably 0.157 or less, and particularly preferably 0.100 or less. If the ceramic base contains Yb in the above-mentioned ratio and the Si / Ca is such an upper limit or less, the volume resistivity of the ceramic base can be made to increase more remarkably. 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 further preferably 0.065 or more. Such a ceramic base 1 has a relatively high volume resistivity. The volume resistivity of the ceramic base 1 at 500°C is, for example, 5.0 x 10 8 Ω·cm or more, preferably 1.0 x 10 9 Ω·cm or more, more preferably 5.0 x 10 9 Ω·cm or more, and further preferably 7.5 x 10 9 Ω·cm or more. On the other hand, the upper limit of the volume resistivity of the ceramic base 1 at 500°C is typically 1.0 x 10 10 Ω·cm. It is to be noted that the volume resistivity at 500°C is measured, for example, in accordance with JIS C2141-1992. 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. It is to be noted that the thermal conductivity of the ceramic base at 500°C is measured, for example, in accordance with JIS R1611. 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. It is to be noted that the average linear expansion coefficient is measured, for example, in accordance with JIS R1618. The heat generating body 2 contains any appropriate metal. As the metal, for example, tantalum (Ta), tungsten (W), molybdenum (Mo), tungsten carbide (WC), titanium nitride (TiN), platinum (Pt), rhenium (Re), hafnium (Hf), and alloys thereof can be mentioned. Among the metals, W, Mo, and W-Mo alloys can be mentioned as preferable. If the heat generating body contains such a metal, the linear expansion coefficient of the ceramic base described above and the linear expansion coefficient of the heat generating body can be made to be stable and close to each other. Therefore, the manufacturing stability of the heater for a semiconductor manufacturing apparatus can be further improved. The average linear expansion coefficient of the heat generating body 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 absolute value of the difference between the average linear expansion coefficients of the ceramic base 1 and the heat generating body 2 in the temperature range of 50°C to 1000°C is, for example, 0.5 ppm / °C or less, and preferably 0.3 ppm / °C or less. On the other hand, the lower limit of the absolute value of the difference between the average linear expansion coefficients of the ceramic base 1 and the heat generating body 2 is typically 0.1 ppm / °C. B. Details of the heater for semiconductor manufacturing apparatus Hereinafter, details of each component of the heater for semiconductor manufacturing apparatus will be described. B-1. Ceramic base The ceramic base 1 can have any appropriate shape corresponding to the use of the heater for semiconductor manufacturing apparatus. As the shape of the ceramic base 1, a plate shape can be typically mentioned. The ceramic base 1 preferably has a circular plate shape. Typically, the ceramic base 1 has a mounting surface la on which the semiconductor substrate 8 is mounted. The mounting surface la is one surface in the thickness direction of the ceramic base 1. The thickness of the ceramic base 1 is, for example, 10 mm to 40 mm. As described above, the ceramic base 1 contains AlN as a main component, and contains two or more kinds of rare earth elements including Yb as a subcomponent. Typically, such a ceramic base 1 contains an AlN crystal phase, and a ytterbia crystal phase. In one embodiment, the AlN crystal phase has a polycrystalline structure in which a plurality of AlN crystal grains are combined with each other. The average particle diameter of the plurality of AlN crystal grains is, for example, 2 μm to 5 μm, and preferably 3 μm to 4.5 μm. Typically, the ytterbia crystal phase exists at the grain boundary between the AlN grains. In the case where the rare earth elements include Yb and yttrium (Y), the ceramic base 1 further contains a yttria crystal phase. Typically, the yttria crystal phase exists at the grain boundary between the AlN grains. The ceramic base 1 can contain other crystal phases in addition to the AlN crystal phase, the ytterbia crystal phase, and the yttria crystal phase, or can substantially not contain other crystal phases. In one embodiment, in the ceramic base 1, as the crystal phases, only the AlN crystal phase, the ytterbia crystal phase, and the yttria crystal phase are contained, and substantially no other crystal phases are contained. The porosity of the ceramic base 1 is, for example, 1% or less. Note that the porosity is measured, for example, in accordance with JIS R1634. The relative density of the ceramic substrate 1 is, for example, 3.2 g / cc to 3.4 g / cc, preferably 3.25 g / cc to 3.35 g / cc. Note that the relative density of the ceramic substrate is the bulk density relative to the theoretical density of the ceramic substrate. The bulk density of the ceramic substrate is measured, for example, in accordance with JIS R1634. In the illustrated example, such a ceramic substrate 1 is supported by a ceramic shaft 5. The ceramic shaft 5 is attached to the surface of the ceramic substrate 1 on the side opposite the mounting surface la. 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 substrate 1. In the illustrated example, the axis of the ceramic shaft 5 and the center of the ceramic substrate 1 are substantially coincident when viewed in the thickness direction of the ceramic substrate 1. The ceramic shaft 5 is composed of any appropriate ceramic material, but from the viewpoint of matching the thermal expansion difference with the ceramic substrate, it is preferable to be of the same material as the ceramic substrate, i.e., a ceramic shaft containing aluminum nitride. B-2. Heat-Generating Body The heat-generating body 2 is configured to generate heat when a voltage is applied. The number of heat-generating bodies 2 implanted in the ceramic substrate 1 is not particularly limited. A plurality of heat-generating bodies 2 can also be implanted in the ceramic substrate 1. In this case, the plurality of heat-generating bodies 2 exist separately from each other in the thickness direction of the ceramic substrate 1. In the illustrated example, one heat-generating body 2 is implanted in the ceramic substrate 1. The heat-generating body 2 has any appropriate shape. As the heat-generating body 2, for example, a coil shape, a zigzag shape, or a mesh shape can be given. The size (wire diameter) of the heat-generating body 2 in the thickness direction of the ceramic substrate 1 is, for example, 0.3 mm to 1.0 mm, preferably 0.4 mm to 0.7 mm. The volume resistivity of the heat-generating body 2 at 500°C is, for example, 1.9 x 10 －5 Ω·cm or less, preferably 1.8 x 10 －5 Ω·cm or less. On the other hand, the lower limit of the volume resistivity of the heat-generating body 2 at 500°C is typically 1.6 x 10 －5 Ω·cm. In the illustrated example, a first power supply rod 6 is electrically connected to the heat-generating body 2. A voltage can be applied to the heat-generating body 2 via the first power supply rod 6. The first power supply rod 6 is composed of any appropriate electrically conductive material. The first power supply rod 6 passes through the inside space of the ceramic shaft 5 to be electrically connected to the heat-generating body 2. B-3. Internal Electrode In one embodiment, the heater 100 for a semiconductor manufacturing apparatus further has an internal electrode 3. The internal electrode 3 is implanted in the ceramic substrate 1. In the illustrated example, the internal electrode 3 is located between the mounting surface la and the heat-generating body 2 in the thickness direction of the ceramic substrate 1. Representatively, the internal electrode 3 functions as an ESC electrode. In the case where the internal electrode 3 functions as an ESC electrode, if a DC voltage is applied to the internal electrode 3 in a state where the semiconductor substrate 8 is placed on the placement surface la, the internal electrode 3 takes either one of positive and negative charges depending on the polarity of the applied DC voltage, and the other one of the positive and negative charges existing in the semiconductor substrate 8 moves to the placement surface la side in the semiconductor substrate 8. Thus, a Johanson-Rubin (JR) force is generated between the semiconductor substrate 8 and the internal electrode 3, and the semiconductor substrate 8 is held by the ceramic base 1. Although not shown, the semiconductor manufacturing apparatus heater 100 can have a plurality of internal electrodes 3. In one embodiment, the internal electrode 3 functions as an RF electrode (i.e., a high-frequency electrode) for plasma processing. That is, the internal electrode 3 preferably functions as an RF / ESC electrode. As the plasma processing, for example, film formation processing, etching processing can be cited. In the case where such plasma processing is performed on the semiconductor substrate 8 on the placement surface la, an upper electrode is arranged on the side opposite to the internal electrode 3 with respect to the semiconductor substrate 8. If high-frequency power is supplied to the internal electrode 3 in this state, a processing gas can be excited to generate plasma in the space between the ceramic base 1 and the upper electrode. The semiconductor substrate 8 is subjected to plasma processing by the use of this plasma. The internal electrode 3 can have any appropriate shape. Representatively, the internal electrode 3 has a plate shape. In one embodiment, the internal electrode 3 has a shape similar to the outer shape of the ceramic base 1 as 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 as 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. Representatively, the internal electrode 3 contains the same metal as the above-described heating element 2. Therefore, the internal electrode 3 has the same range of average linear expansion coefficient in the temperature range of 50°C to 1000°C as the above-described heating element 2, for example. In addition, the range of absolute value of difference between the average linear expansion coefficients of the ceramic base 1 and the internal electrode 3 in the temperature range of 50°C to 1000°C is the same as the range of absolute value of difference between the average linear expansion coefficients of the above-described ceramic base 1 and the heating element 2, for example. Thus, even if the semiconductor manufacturing apparatus heater has an internal electrode, it is possible to suppress breakage such as cracking of the ceramic base in the manufacture of the semiconductor manufacturing apparatus heater. In the illustrated example, the second power supply rod 7 is electrically connected to the inner electrode 3. The voltage (or high-frequency power) described above can be applied to the inner electrode 3 via the second power supply rod 7. Typically, the second power supply rod 7 is made of the same metal as the inner electrode 3. The second power supply rod 7 passes through the inner space of the ceramic shaft 5 to be electrically connected to the inner electrode 3. C. Method for manufacturing a heater for semiconductor manufacturing apparatus Next, a method for manufacturing a heater for semiconductor manufacturing apparatus according to one embodiment will be described. The method for manufacturing a heater for semiconductor manufacturing apparatus according to one embodiment includes: a mixing step of mixing raw material powders of a ceramic base; a molding step of preparing a molded body in which a heating element is embedded, from a 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. C-1. Mixing step In the mixing step, the AlN powder and two or more kinds of rare earth element powders are mixed to prepare a mixed powder. In one embodiment, the AlN powder, Yb2O3 powder, and Y2O3 powder are mixed to prepare a raw material mixture. The AlN powder and / or the rare earth element powder can contain the above-described trace components. Alternatively, the trace components can be added to the raw material mixture as needed. 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 further preferably 0.8 parts by mass or more, relative to 100 parts by mass of the 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 the AlN powder. The amount of Y2O3 powder added is, for example, 0.5 parts by mass or more, preferably 1.0 parts by mass or more, and more preferably 3.0 parts by mass or more, relative to 100 parts by mass of the AlN. On the other hand, the upper limit of the amount of Y2O3 added is typically 4.3 parts by mass, relative to 100 parts by mass of the AlN powder. Any appropriate mixing device can be used in the mixing step. As the mixing device that can be used in the mixing step, for example, a ball mill, a bead mill, or a vibration mill can be mentioned, and a ball mill is preferably mentioned. Alternatively, the mixing method in the mixing step can be dry mixing or wet mixing. In one embodiment, dry mixing is performed in the mixing step. The environmental conditions in the mixing step are not particularly limited. Typically, the mixing step is performed at normal temperature (25°C) and normal pressure (0.1 MPa). The implementation time of the mixing step is arbitrarily and appropriately set. The implementation time of the mixing step is, for example, 1 hour to 30 hours. By the above operation, a raw material mixture containing the AlN powder and two or more kinds of rare earth element powders (representatively, Yb2O3 powder and Y2O3 powder) is prepared. In the case where the mixing process is dry mixing, the raw material mixture has a powder shape; in the case where the mixing process is wet mixing, the raw material mixture has a slurry shape. The raw material mixture is granulated as necessary. As a granulation method, for example, a spray drying method can be given. By this, a granulated product (raw material granules) of the raw material mixture is prepared. C-2. Shaping Process Next, in the shaping process, the raw material mixture is shaped using an arbitrary appropriate shaping method, in a state where a previously prepared heat generating body 2 is implanted in a desired position with respect to the raw material mixture. As the shaping method, for example, press molding, tape casting, cold isostatic pressing (CIP) molding can be given, and press molding is preferable. The pressure in the press molding is, for example, 10 kgf / cm 2 ~ 500 kgf / cm 2 . By this, a shaped body having a desired shape is prepared. C-3. Firing Process In the firing process, the shaped body is fired using an arbitrary appropriate firing method. Representatively, the shaped body is fired in a vacuum or a non-oxidizing atmosphere. For example, after being heated from a normal temperature (23°C) to a prescribed firing temperature, the firing temperature is maintained for a prescribed firing time. The firing temperature is, for example, 1600°C to 1900°C, and is preferably 1650°C to 1850°C. The firing time is, for example, 0.5 hours to 20 hours. As the firing method, for example, hot pressing, hot isostatic pressing (HIP) can be given, and hot pressing is preferable. In the hot pressing, representatively, the shaped body is disposed in a hot pressing mold (for example, a graphite mold), heated to the firing temperature as described above, and pressed at a prescribed pressure. The pressure in the hot pressing is, for example, 5 MPa to 50 MPa. By the above operation, a heater for a semiconductor manufacturing apparatus provided with a ceramic base and a heat generating body implanted in the ceramic base is manufactured. Example Hereinafter, the present application is specifically described using examples and comparative examples, but the present application is not limited by these examples. The measurement method of each characteristic is as follows. (1) Measurement of Average Linear Expansion Coefficient of Each of Ceramic Base and Heat Generating Body The average linear expansion coefficients of the ceramic base and the heating element of the semiconductor manufacturing apparatus heater manufactured in the examples and comparative examples were measured in accordance with JIS R1618. The average linear expansion coefficients of the ceramic base and the heating element, the difference between the average linear expansion coefficients thereof are shown in Table 1. (2) Measurement of Volume Resistivity of Ceramic Base The volume resistivity of the ceramic base of the semiconductor manufacturing apparatus heater manufactured in the examples and comparative examples was measured in accordance with JIS C2141. The results thereof are shown in Table 1. << Example 1 >> AlN powder 95 parts by mass, Y2O3 powder 3 parts by mass, and Yb2O3 powder 1.3 parts by mass were put into a ball mill and dry mixed for 10 hours. Thus, a mixed powder (raw material mixture) was obtained. Thereafter, the mixed powder was granulated by a spray drying method. In addition, a heating element of Mo material and having a coil shape was prepared. Next, the granules of the mixed powder were filled in a prescribed mold, and the heating element was implanted in a desired position. Thereafter, the granules of the mixed powder filled in the mold were subjected to uniaxial press molding, and a molded body having a circular plate shape was obtained. The pressure in the uniaxial press molding was 100 kgf / cm 2 The diameter of the molded body was 350 mm. The thickness of the molded body was 50 mm. Next, the molded body was fired by a hot press method. More specifically, first, the molded body was housed in a hot press mold made of graphite, and the molded body was fired at 1850°C for 5 hours by the hot press method. The pressure of the hot press was 10 MPa. By the above operation, a semiconductor manufacturing apparatus heater provided with a ceramic base and a heating element was manufactured. Thereafter, the semiconductor manufacturing apparatus heater was cooled to room temperature (25°C). Note that the ceramic base contained, in addition to AlN, Yb, and Y, Ca and Si as trace components. The content ratios of Y (yttrium) and Yb (ytterbium) each, the total content ratio of rare earth elements, and the content ratio of trace components, converted into oxides, are shown in Table 1 below. << Example 2 >> Y2O3 powder was changed to 3.5 parts by mass, Yb2O3 powder was changed to 0.9 parts by mass, and the content ratios of trace components (Ca and Si) were adjusted to the values given in Table 1, and otherwise, a semiconductor manufacturing apparatus heater was manufactured in the same manner as in Example 1. The content ratios of Y (yttrium) and Yb (ytterbium) each, the total content ratio of rare earth elements, and the content ratio of trace components, converted into oxides, are shown in Table 1 below. << Example 3 >> A heater for semiconductor manufacturing equipment was produced 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 contents of trace components (Ca and Si) were adjusted to the values ​​shown in Table 1. The contents of Y (yttrium) and Yb (ytterbium) calculated as oxides, the total content of rare earth elements, and the contents of trace components are shown in Table 1 below. <<Example 4>> A heater for semiconductor manufacturing equipment was produced 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 contents of trace components (Ca and Si) were adjusted to the values ​​shown in Table 1. The contents of Y (yttrium) and Yb (ytterbium) calculated as oxides, the total content of rare earth elements, and the contents of trace components are shown in Table 1 below. <<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 contents of trace components (Ca and Si) were adjusted to the values ​​shown in Table 1. The contents of Y (yttrium) and Yb (ytterbium) calculated as oxides, the total content of rare earth elements, and the contents of trace components are shown in Table 1 below. <<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 contents of trace components (Ca and Si) were adjusted to the values ​​shown in Table 1. The contents of Y (yttrium) and Yb (ytterbium) calculated as oxides, the total content of rare earth elements, and the contents of trace components are shown in Table 1 below. <<Example 7>> A heater for semiconductor manufacturing equipment was produced 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 contents of trace components (Ca and Si) were adjusted to the values ​​shown in Table 1. The contents of Y (yttrium) and Yb (ytterbium) calculated as oxides, the total content of rare earth elements, and the contents of trace components are shown in Table 1 below. <<Example 8>> A heater for semiconductor manufacturing equipment was produced 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 contents of trace components (Ca and Si) were adjusted to the values ​​shown in Table 1. The contents of Y (yttrium) and Yb (ytterbium) calculated as oxides, the total content of rare earth elements, and the contents of trace components are shown in Table 1 below. <<Comparative Example 1>> A mixed powder was prepared by mixing 96 parts by mass of AlN powder and 4 parts by mass of Y2O3 powder, and the content ratio of the trace components (Ca and Si) was adjusted to the values given in Table 1, and otherwise, a heater for a semiconductor manufacturing apparatus was manufactured in the same manner as in Example 1. The content ratio of Y (yttrium) and Yb (ytterbium) each, the total content ratio of rare earth elements, and the content ratio of trace components, converted into oxides, are shown in Table 1 below. <<Comparative Example 2>> A mixed powder was prepared by mixing 96 parts by mass of AlN powder and 4 parts by mass of Y2O3 powder, and the content ratio of the trace components (Ca and Si) was adjusted to the values given in Table 1, and otherwise, a heater for a semiconductor manufacturing apparatus was manufactured in the same manner as in Example 1. The content ratio of Y (yttrium) and Yb (ytterbium) each, the total content ratio of rare earth elements, and the content ratio of trace components, converted into oxides, are shown in Table 1 below. <<Comparative Example 3>> A mixed powder was prepared by mixing 96 parts by mass of AlN powder and 4 parts by mass of Y2O3 powder, and the content ratio of the trace components (Ca and Si) was adjusted to the values given in Table 1, and otherwise, a heater for a semiconductor manufacturing apparatus was manufactured in the same manner as in Example 1. The content ratio of Y (yttrium) and Yb (ytterbium) each, the total content ratio of rare earth elements, and the content ratio of trace components, converted into oxides, are shown in Table 1 below. <<Comparative Example 4>> A mixed powder was prepared by mixing 96 parts by mass of AlN powder and 4 parts by mass of Y2O3 powder, and the content ratio of the trace components (Ca and Si) was adjusted to the values given in Table 1, and otherwise, a heater for a semiconductor manufacturing apparatus was manufactured in the same manner as in Example 1. The content ratio of Y (yttrium) and Yb (ytterbium) each, the total content ratio of rare earth elements, and the content ratio of trace components, converted into oxides, are shown in Table 1 below. Table 1 <Evaluation> The relationship between the volume resistivity of the ceramic substrate at 500°C and the appearance of the ceramic substrate is shown in Table 1. In Examples 1 to 8, the volume resistivity of the ceramic substrate could be increased, and the color unevenness (appearance OK) of the ceramic substrate could be sufficiently suppressed. Therefore, it was found that a heater for a semiconductor manufacturing apparatus having an excellent volume resistivity could be stably manufactured. Note that in Comparative Examples 2 and 4, the volume resistivity of the ceramic substrate was relatively high, but the color unevenness was significant, and the product was not qualified (appearance NG). Industrial Applicability The heater for a semiconductor manufacturing apparatus according to the embodiment of the present application is typically used in the manufacturing of semiconductors, and can be particularly preferably used as a ceramic heater that holds and heats a semiconductor substrate.

Claims

1. A heater for a semiconductor manufacturing device, comprising: a ceramic substrate comprising aluminum nitride; and A heating element, which is embedded in the ceramic substrate. The ceramic matrix contains two or more rare earth elements, and contains Yb as the rare earth element. The total content of rare earth elements in the ceramic matrix is ​​4.5% by mass or less in terms of oxides. The Yb content in the ceramic base is 0.3 mass % or more and 1.3 mass % or less in terms of oxide.

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

3. The heater for semiconductor manufacturing equipment according to claim 1 or 2, wherein The ceramic base contains Y as the rare earth element.

4. The heater for semiconductor manufacturing equipment according to claim 1 or 2, wherein The Ca content in the ceramic base is 300 ppm or less.

5. The heater for semiconductor manufacturing equipment according to claim 1 or 2, wherein The content of Ca in the ceramic base is 80 ppm or more.

6. The heater for semiconductor manufacturing equipment according to claim 1 or 2, wherein The ceramic matrix further comprises Ca and Si, The mass ratio of Si to Ca in the ceramic matrix is ​​0.060 or more and 0.20 or less. The mass ratio of Yb to Y in the ceramic base is 0.10 or more and 0.45 or less.

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