WO2022195947A1

WO2022195947A1 - Aln ceramic substrate, and heater for semiconductor manufacturing device

Info

Publication number: WO2022195947A1
Application number: PCT/JP2021/040196
Authority: WO
Inventors: 啓太山名; 和宏 ▲のぼり▼
Original assignee: 日本碍子株式会社
Priority date: 2021-03-18
Filing date: 2021-11-01
Publication date: 2022-09-22
Also published as: TWI798917B; TW202239262A

Abstract

This AlN ceramic substrate contains yttrium-aluminate, wherein the volume resistivity at 550℃ is at least ３×１０⁹Ωｃｍ.

Description

AlN ceramic substrate and heater for semiconductor manufacturing equipment

The present invention relates to AlN ceramic substrates and heaters for semiconductor manufacturing equipment.

2. Description of the Related Art As disclosed in Patent Document 1, a known heater for a semiconductor manufacturing apparatus includes an AlN ceramic substrate and a resistance heating element embedded inside the AlN ceramic substrate. Such heaters for semiconductor manufacturing equipment are used to heat a wafer mounted on the surface of an AlN ceramic substrate. Further, as a heater for semiconductor manufacturing equipment, as disclosed in Patent Document 2, a heater in which a resistance heating element and an electrostatic electrode are embedded in an AlN ceramic base is also known. In such a heater for a semiconductor manufacturing apparatus, if current leaks from the resistance heating element to the wafer or from the electrostatic electrode to the wafer, the wafer will be damaged. Therefore, it is preferable to control the volume resistivity of the AlN ceramic substrate to a high value. In view of this point, in Patent Document 3, as an AlN ceramic substrate, a mixed powder obtained by adding yttrium oxide powder as a sintering aid to AlN raw material powder is granulated, and the granules are used to produce a disk-shaped molded body. A hot press sintering of the compact at 1850 to 1890° C. is disclosed. The volume resistivity of the AlN ceramic substrate at 550° C. is as high as 1×10 ⁹ to 2.6×10 ⁹ Ωcm.

JP 2008-153194 A JP 2005-281046 A Japanese Patent No. 6393006

However, when an AlN ceramic substrate having a volume resistivity of 1×10 ⁹ to 2.6×10 ⁹ Ωcm at 550° C. is used, the leakage current flowing through the AlN ceramic substrate may not be sufficiently blocked.

The present invention has been made to solve such problems, and the main object thereof is to provide an AlN ceramic substrate having a higher volume resistivity at high temperatures than conventional ones.

The AlN ceramic substrate of the present invention is
An AlN ceramic substrate comprising yttrium aluminate,
Volume resistivity at 550 ° C. is 3 × 10 ⁹ Ωcm or more,
It is.

This AlN ceramic substrate has a higher volume resistivity at high temperatures than conventional ones. Therefore, when this AlN ceramic substrate is used as an AlN ceramic substrate in which a resistance heating element of a heater for semiconductor manufacturing equipment is embedded, it is possible to sufficiently prevent leakage current from flowing through the AlN ceramic substrate.

A volume resistivity of 5×10 ⁹ Ωcm or more is preferable because leakage current can be further suppressed, and a volume resistivity of 1×10 ¹⁰ Ωcm or more is more preferable because the thickness of the ceramic substrate can be further reduced. Examples of yttrium aluminate include Y ₄ Al ₂ O ₉ (YAM) and YAlO ₃ (YAL).

In the AlN ceramic substrate of the present invention, the average particle size of the AlN sintered particles is preferably 1.5 μm or more and 2.5 μm or less, and yttrium aluminate exists in a dispersed state at the grain boundaries between the AlN sintered particles. is preferred. In this way, the yttrium aluminate is finely and uniformly dispersed. Therefore, it is possible to prevent a current path from occurring in the yttrium aluminate and increase the volume resistivity of the AlN ceramic substrate at high temperatures.

A heater for semiconductor manufacturing equipment according to the present invention has a resistance heating element embedded in the AlN ceramic substrate described above.

In this heater for semiconductor manufacturing equipment, the volume resistivity of the AlN ceramic substrate at high temperatures is even higher than before. Therefore, it is possible to sufficiently prevent leakage current from flowing through the AlN ceramic substrate.

In the heater for a semiconductor manufacturing apparatus of the present invention, the resistance heating element is preferably made of Mo, and the AlN ceramic base includes a first annular layer surrounding the resistance heating element so as to be in contact with the resistance heating element. , and a second annular layer surrounding the first annular layer, and the first annular layer preferably has a higher Y content and a wider layer width than the second annular layer. The first annular layer may continuously surround the resistive heating element and the second annular layer may continuously surround the first annular layer. The second annular layer may have a shape in which a portion of the annular shape has a discontinuous portion, and a shape that forms a single ring (smooth ring) if the discontinuous portion is virtually connected. In addition, even if the average value per unit width of the Y content distributed in the width direction of the first annular layer is larger than the average value per unit width of the Y content distributed in the width direction of the second annular layer good.

FIG. 2 is a plan view of the heater 10 for semiconductor manufacturing equipment; AA sectional view of FIG. Sectional drawing of the modification of the 2nd annular layer L2. 4 is a SEM photograph of a cross section containing Mo of the AlN ceramic sintered body 12 of Example 1. FIG. 4 is a schematic diagram of a cross section containing Mo of the AlN ceramic sintered body 12 of Example 1. FIG. 4 is a graph showing the results of EPMA analysis of Example 1. FIG. 4 is a SEM photograph of a cross section containing Mo of the AlN ceramic sintered body of Comparative Example 1. FIG. 4 is a schematic diagram of a cross section containing Mo of the AlN ceramic sintered body of Comparative Example 1. FIG. 4 is a graph showing the results of EPMA analysis of Comparative Example 1. FIG.

A heater 10 for semiconductor manufacturing equipment, which is a preferred embodiment of the present invention, will be described below. FIG. 1 is a plan view of a heater 10 for semiconductor manufacturing equipment, and FIG. 2 is a sectional view taken along line AA of FIG. Note that the dashed-dotted lines in FIG. 1 indicate the boundaries of the zones. In FIG. 1, the inner and outer

resistance heating elements

30 and 40 are indicated by hidden lines (dotted lines), but the RF electrode 20 is omitted.

A heater 10 for a semiconductor manufacturing apparatus has an RF electrode 20, an inner circumference side resistance heating element 30, and an outer circumference side resistance heating element 40 embedded in a disk-shaped AlN ceramic substrate 12.

The AlN ceramic substrate 12 contains yttrium aluminate (for example, YAL or YAM), and has a wafer mounting surface 12a on its upper surface. The volume resistivity of the AlN ceramic substrate 12 at 550° C. is 3×10 ⁹ Ωcm or higher, preferably 5×10 ⁹ Ωcm or higher, more preferably 1×10 ¹⁰ Ωcm or higher. The AlN ceramic substrate 12 is divided into an inner zone Zin and an outer zone Zout when viewed from above. The inner peripheral zone Zin is a circular zone with a diameter smaller than the diameter of the AlN ceramic substrate 12 . The outer zone Zout is an annular zone surrounding the inner zone Zin.

The RF electrode 20 is a circular metal mesh (eg, Mo coil) and is provided substantially parallel to the wafer mounting surface 12a. The RF electrode 20 is buried closer to the wafer mounting surface 12 a than the inner resistance heating element 30 and the outer resistance heating element 40 . The diameter of RF electrode 20 is slightly smaller than the diameter of AlN ceramic substrate 12 . A high-frequency voltage is applied between the RF electrode 20 and a parallel plate electrode (not shown) spaced apart from the wafer mounting surface 12a. The RF electrode 20 is connected to the RF connecting member 22 . The RF connection member 22 has an upper end connected to the lower surface of the RF electrode 20 and a lower end exposed from the lower surface 12 b of the AlN ceramic substrate 12 . The RF connection member 22 is provided so as to pass through the gaps in the wiring pattern of the inner resistance heating element 30 . An RF connecting member 22 is used to apply a high frequency voltage between the RF electrode 20 and the parallel plate electrodes.

The inner circumference side resistance heating element 30 is a metal coil (eg, Mo coil) and is provided substantially parallel to the wafer mounting surface 12a. The inner peripheral resistance heating element 30 is wired from one of a pair of

terminals

32 and 34 provided near the center of the AlN ceramic substrate 12 to the entire inner peripheral zone Zin in a unicursal manner without crossing. It is provided so as to reach the other of the pair of

terminals

32 and 34 . A pair of

terminals

32 and 34 are connected to a pair of inner peripheral

side connecting members

36 and 38 . The lower ends of the pair of inner peripheral

side connecting members

36 and 38 are exposed from the lower surface 12b of the AlN ceramic substrate 12. As shown in FIG. When the inner peripheral resistance heating element 30 is to generate heat, a voltage is applied between the pair of

terminals

32 and 34 using the pair of inner peripheral connecting

members

36 and 38 .

The outer-peripheral-side resistance heating element 40 is a metal coil (for example, a Mo coil) and is provided substantially parallel to the wafer mounting surface 12a. The outer resistance heating element 40 passes through the inner zone Zin from one of a pair of

terminals

42 and 44 provided near the center of the AlN ceramic substrate 12 and is led out to the outer zone Zout. , and then pulled back to the inner peripheral zone Zin to reach the other of the pair of

terminals

42 and 44 . A pair of

terminals

42 and 44 are connected to a pair of outer peripheral

side connection members

46 and 48 . The lower ends of the pair of outer peripheral

side connecting members

46 and 48 are exposed from the lower surface 12b of the AlN ceramic substrate 12. As shown in FIG. When the outer resistance heating element 40 is caused to generate heat, a voltage is applied between the pair of

terminals

42 and 44 using the pair of

outer connection members

46 and 48 . The outer resistance heating element 40 is provided on the same plane as the inner resistance heating element 30 .

Next, a usage example of the heater 10 for semiconductor manufacturing equipment will be described. First, the heater 10 for semiconductor manufacturing equipment is installed in a chamber (not shown). A wafer W is mounted on the wafer mounting surface 12a of the heater 10 for a semiconductor manufacturing apparatus, and an external power source is connected to the

connection members

36 and 38 of the inner peripheral resistance heating element 30, so that an electric current is generated between the pair of

terminals

32 and 34. Apply a voltage to At the same time, another external power supply is connected to the

connection members

46 and 48 of the outer resistance heating element 40 to apply a voltage between the pair of

terminals

42 and 44 . As a result, the inner peripheral resistance heating element 30 and the outer peripheral resistance heating element 40 generate heat to heat the wafer W to a predetermined temperature. In this embodiment, the temperature of the inner zone Zin and the outer zone Zout can be individually controlled. In this state, a high-frequency voltage is applied between a parallel plate electrode (not shown) and the RF electrode 20 spaced apart above the wafer W, and the wafer W is subjected to various processes necessary for fabricating semiconductor chips. After completion of the processing, the application of the high frequency voltage to the RF electrode 20 and the application of voltage to the inner and outer

resistance heating elements

30 and 40 are terminated, and the wafer W is removed from the wafer mounting surface 12a.

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

Subsequently, Y ₂ O ₃ powder is added as a sintering aid to the prepared AlN raw material powder and mixed to obtain a mixed powder, which is granulated by spray drying. Y ₂ O ₃ is added so as to be 4 to 6% by mass with respect to the entire mixed powder. The average particle size of the Y ₂ O ₃ powder is preferably of submicron order. As a mixing method, wet mixing using an organic solvent may be employed, or dry mixing such as a ball mill, vibration mill, and dry bag mixing may be employed.

Subsequently, using granules of the mixed powder, the RF electrode 20 and the inner and outer peripheral

resistance heating elements

30 and 40 are embedded in the granules and molded to produce a compact. Then, the formed body is fired to obtain an AlN sintered body. Thus, the heater 10 for semiconductor manufacturing equipment is obtained. As a firing method, for example, hot press firing can be used. The maximum temperature (firing temperature) during hot press firing is preferably set in the range of 1650°C or higher and 1750°C or lower, preferably 1670°C or higher and 1730°C or lower. It is preferable that the firing temperature is maintained for 0.5 to 100 hours, the press pressure is 5 to 50 MPa, and the atmosphere is a nitrogen atmosphere or a vacuum atmosphere (for example, 0.13 to 133.3 Pa). When performing hot press firing, it is preferable to perform an operation of keeping for at least one hour or more until the maximum temperature is reached (from 1500° C. to a temperature 10° C. lower than the maximum temperature) once or more.

Looking at the SEM photograph of the cross section of the AlN ceramic substrate 12 of the obtained heater 10 for semiconductor manufacturing equipment, the average particle size of the AlN sintered particles is preferably 1.5 μm or more and 2.5 μm or less. It is preferable that yttrium aluminate, which is finer than the AlN sintered particles, is present in a dispersed state at grain boundaries between the AlN sintered particles. If the average particle size of the AlN sintered particles is larger than this, the yttrium aluminate exists in a wet state at the grain boundary between the AlN sintered particles, making it easier to form a current path. not high enough. On the other hand, when the average particle size of the AlN sintered particles is 1.5 μm or more and 2.5 μm or less, yttrium aluminate exists in a state of being dispersed in the grain boundaries between the AlN sintered particles, so a current path is formed. and the volume resistivity at high temperatures is sufficiently high.

Further, when Mo is used for the inner and outer

resistance heating elements

30 and 40, the AlN ceramic substrate 12 has an inner surface so as to be in contact with the inner resistance heating element 30 as shown in the enlarged view of FIG. A first annular layer L1 continuously (that is, without interruption) surrounding the circumferential resistance heating element 30 and a second annular layer L2 continuously surrounding the first annular layer L1 appear. The first annular layer L1 has a higher Y content and a wider layer width than the second annular layer L2. That is, the first annular layer L1 is a Y-rich layer, and the second annular layer L2 is a Y-poor layer. Such a microstructure is also seen around the outer resistance heating element 40 . The reason why the first annular layer L1 becomes the Y-rich layer is considered as follows.

When the firing temperature exceeds 1750° C., the Y concentration in the region in contact with the Mo inner peripheral resistance heating element 30 decreases. When the firing temperature exceeds 1750 ° C., Mo has a high affinity for oxygen and tries to take oxygen from the yttrium aluminate around Mo, whereas the yttrium aluminate around Mo does not want to take oxygen. Therefore, it is considered to move to a position away from Mo. As a result, when the firing temperature exceeds 1750° C., the Y concentration in the region of the AlN ceramic substrate 12 in contact with the Mo inner resistance heating element 30 is considered to decrease. This may be one of the reasons why the volume resistivity at high temperatures is not sufficiently high.

On the other hand, when the firing temperature is 1650° C. or higher and 1750° C. or lower, the Y concentration in the region (first annular layer L1) in contact with the Mo inner circumference side resistance heating element 30 becomes relatively high. If the firing temperature is 1750° C. or lower, it is difficult for Mo to deprive the surrounding yttrium aluminate of oxygen. As a result, when the firing temperature is 1650° C. or higher and 1750° C. or lower, the Y concentration in the region (first annular layer L1) of the AlN ceramic substrate 12 that is in contact with the Mo inner peripheral side resistance heating element 30 does not decrease. It is thought that it will become a rich layer. This may be one of the reasons why the volume resistivity at high temperatures is sufficiently high.

According to the semiconductor manufacturing apparatus heater 10 of the present embodiment described above, the volume resistivity of the AlN ceramic substrate 12 at a high temperature (550° C.) is 3×10 ⁹ Ωcm or more, which is higher than that of the conventional heater. Therefore, it is possible to sufficiently prevent leakage current from flowing through the AlN ceramic substrate 12 . A volume resistivity of 5×10 ⁹ Ωcm or more is preferable because leakage current can be further suppressed, and a volume resistivity of 1×10 ¹⁰ Ωcm or more is more preferable because the thickness of the ceramic substrate can be further reduced.

In addition, the average particle size of the AlN sintered particles in the AlN ceramic substrate 12 is preferably 1.5 μm or more and 2.5 μm or less, and yttrium aluminate exists in a dispersed state at the grain boundary between the AlN sintered particles. is preferred. In this way, the yttrium aluminate is finely and uniformly dispersed. Therefore, it is possible to prevent the occurrence of a current path of yttrium aluminate and increase the volume resistivity of the AlN ceramic substrate 12 at high temperatures.

Furthermore, the inner and outer peripheral

resistance heating elements

30 and 40 are preferably made of Mo. and a second annular layer L2 that continuously surrounds the first annular layer L2. The first annular layer L1 has a higher Y content than the second annular layer L2 A wide width is preferred. Such structures are believed to contribute in some way to the high volume resistivity at high temperatures. Such a structure is obtained by performing the operation of keeping for at least one hour or more until the maximum temperature is reached (between 1500 ° C. and 10 ° C. below the maximum temperature) when performing hot press firing. , is likely to occur.

Furthermore, the heater 10 for a semiconductor manufacturing apparatus includes a mixed powder of AlN powder and Y ₂ O ₃ powder (the Y ₂ O ₃ powder is 4% by mass or more and 6% by mass or less of the entire mixed powder), the RF electrode 20 and the inner circumference. By embedding the side and outer peripheral

resistance heating elements

30 and 40 and molding to obtain a molded body, the molded body is hot-press fired at a maximum firing temperature of 1650° C. or higher and 1750° C. or lower. It is obtained. Therefore, it is possible to relatively easily manufacture the heater 10 for semiconductor manufacturing equipment, which can sufficiently prevent the leak current from flowing through the AlN ceramic substrate 12 .

It goes without saying that the present invention is by no means limited to the above-described embodiments, and can be implemented in various forms as long as they fall within the technical scope of the present invention.

For example, in the embodiment described above, the RF electrode 20 is embedded in the AlN ceramic substrate 12, but the RF electrode 20 may be omitted, the RF electrode 20 may be replaced with an electrostatic electrode, or the RF electrode 20 may be replaced with an electrostatic electrode. It may also be used as an electrostatic electrode. When an electrostatic electrode is provided, the wafer W can be attracted and held on the wafer mounting surface 12a by applying a voltage to the electrostatic electrode.

In the above-described embodiment, a metal mesh is exemplified as the RF electrode 20, but a metal plate may be employed. In addition, although the metal coils have been exemplified as the inner and outer peripheral

resistance heating elements

30 and 40, metal ribbons and metal meshes may also be employed. Also, the RF electrode 20 and the inner and outer

resistance heating elements

30 and 40 may be formed by printing a conductive paste in a predetermined shape or pattern.

In the above-described embodiment, the inner resistance heating element 30 is embedded in the inner zone Zin and the outer resistance heating element 40 is embedded in the outer zone Zout. A resistance heating element may be embedded in each zone by dividing it. Alternatively, a single resistance heating element may be wired throughout the AlN ceramic substrate 12 without dividing it into a plurality of zones.

In the above-described embodiment, the inner peripheral side resistance heating element 30 and the outer peripheral side resistance heating element 40 are embedded on the same plane, but they may be embedded on different surfaces.

In the above-described embodiment, the heater 10 for a semiconductor manufacturing apparatus is illustrated, but the AlN ceramic substrate 12 can be used alone without embedding the RF electrode 20 and the inner and outer peripheral

resistance heating elements

30 and 40 in the AlN ceramic substrate 12. can be made with

In the above-described embodiment, the second annular layer L2 has a shape that continuously surrounds the first annular layer L1, but it is not particularly limited to this. For example, as shown in FIG. 3, the second annular layer L2 may have a shape that is not continuous but has an annular portion L2a that is interrupted. The second annular layer L2 forms one ring (smooth ring) if the discontinuous portions L2a are virtually connected.

Examples of the present invention will be described below. In addition, the following examples do not limit the present invention.

[Example 1]
First, AlN raw material powder was prepared. 5% by mass of Y ₂ O ₃ powder was added as a sintering aid to this AlN raw material powder and mixed by a ball mill to obtain a mixed powder, which was granulated by spray drying. Y ₂ O ₃ was added so as to be 5% by mass with respect to the entire mixed powder. Subsequently, using the granules of the mixed powder, a disk-shaped compact was produced. An RF electrode 20 and inner and outer

resistance heating elements

30 and 40 were embedded in the compact. Then, the heater 10 for a semiconductor manufacturing apparatus was produced by hot-press firing the compact. In the hot press firing, the maximum temperature (firing temperature) during firing was 1720° C., the time to keep the firing temperature was 2 hours, the press pressure was 20 MPa, and the atmosphere was nitrogen atmosphere. In the hot press firing, the operation of keeping for 1 hour was performed twice or more until the maximum temperature was reached (from 1500° C. to a temperature 10° C. lower than the maximum temperature).

The crystal phase contained in the AlN ceramic substrate 12 was identified by X-ray diffraction. About 0.5 g of powder was measured for X-ray diffraction with a Bruker AXS D8 ADVANCE. The measurement conditions were a CuKα ray source, a tube voltage of 40 kV, and a tube current of 40 mA. Rietveld analysis was performed on the measurement results to identify and quantify the crystal phase. Crystal phases identified from the XRD profile were AlN, YAM, and YAL, and TiN was not confirmed.

[Comparative Example 1]
A heater for a semiconductor manufacturing apparatus was manufactured in the same manner as in Example 1, except that the maximum temperature was set to 1850° C. and the operation to keep the temperature was not performed until the maximum temperature was reached. Also in Comparative Example 1, the crystal phases identified from the XRD profile were AlN, YAM, and YAL, and TiN was not confirmed.

[Volume resistivity]
The volume resistivity of the AlN ceramic substrate 12 of the heater 10 for semiconductor manufacturing equipment of Example 1 was measured at 550°C. Measurement was performed as follows. A leak current (current flowing between the wafer W and the RF electrode 20) is obtained when a Si wafer W is placed on the wafer mounting surface 12a and a voltage is applied between the wafer W and the RF electrode 20 (metal mesh) at 550°C. ) was measured. The diameter of the RF electrode 20 was φ355.6 mm, the film thickness of the dielectric layer (the layer between the wafer mounting surface 12a and the RF electrode 20) was 1.02 mm, and the applied voltage was 660V. A plurality of heaters 10 for a semiconductor manufacturing apparatus of Example 1 were produced, and the leak current was measured to be on the order of 40 mA. When the volume resistivity of the AlN ceramic substrate 12 at 550° C. was indirectly calculated from the leak current, the average value was 1.2×10 ¹⁰ Ωcm. On the other hand, when the leakage current was measured in Comparative Example 1 in the same manner as in Example 1, it was on the order of 280 mA, and the average volume resistivity of the AlN ceramic substrate at 550° C. was 2.4×10 ⁹ Ωcm. .

[Microstructure]
When the average particle size of the AlN sintered particles was determined from the SEM photograph of the cross section containing Mo of the AlN ceramic sintered body 12 of Example 1, it was 1.9 μm. Therefore, in Example 1, it was determined that the yttrium aluminate was uniformly dispersed in the grain boundaries between fine AlN sintered particles. When the average particle size of Comparative Example 1 was determined in the same manner, the average particle size was 4.5 μm, which is larger than that of Example 1. The average particle size is obtained by obtaining a secondary electron image (magnification: 3000), drawing a straight line on the image, measuring the length of each line segment that crosses 40 particles, and calculating the average value thereof. did.

FIG. 4 is a SEM photograph of a cross section of the AlN ceramic sintered body 12 of Example 1 including Mo (the inner peripheral resistance heating element 30), and FIG. 5 is a schematic diagram thereof. As can be seen from FIGS. 4 and 5, the first annular layer L1 continuously (without interruption) surrounds Mo so as to be in contact with Mo, and the second annular layer L2 continuously surrounds the first annular layer L1. observed. The first annular layer L1 had a large number of fine white spots (Y derived from yttrium aluminate) dispersed therein, but the second annular layer L2 had almost no such spots and was almost black. FIG. 6 is a graph showing the results of EPMA analysis for Mo and Y along the arrow directions in FIG. In FIG. 6, the portions where the Mo concentration rises sharply and the portions where it falls steeply are regarded as boundaries between the resistance heating element (Mo) and the AlN ceramic sintered body. The Y concentration in the first annular layer L1 was relatively high, but the Y concentration in the second annular layer L2 was almost zero. From this, it was found that the first annular layer L1 was a Y-rich layer and the second annular layer L2 was a Y-poor layer. Also, the layer width of the first annular layer L1 was wider than the layer width of the second annular layer L2.

FIG. 7 is a SEM photograph of a cross section containing Mo of the AlN ceramic sintered body of Comparative Example 1, and FIG. 8 is a schematic diagram thereof. As can be seen from FIGS. 7 and 8, a first layer surrounding Mo so as to be in contact with Mo and a second layer surrounding the first layer were observed. The first layer was almost black with almost no spots, and the second layer had relatively many spots. The second layer was non-continuous and discontinuous. FIG. 9 shows the results of EPMA analysis of Mo and Y along the arrow directions in FIG. In FIG. 9, the portions where the Mo concentration steeply rises and falls are regarded as boundaries between the resistance heating element (Mo) and the AlN sintered body. The Y concentration of the first layer was almost zero and the Y concentration of the second layer was relatively high. From this, it was found that the first layer in Comparative Example 1 was a Y-poor layer and the second layer was a Y-rich layer, that is, contrary to Example 1.

This application claims priority from Japanese Patent Application No. 2021-44405 filed on March 18, 2021, the entire contents of which are incorporated herein by reference.

The present invention can be used for heaters for semiconductor manufacturing equipment.

10 Heater for semiconductor manufacturing equipment, 12 AlN ceramic substrate, 12a Wafer mounting surface, 12b Lower surface, 20 RF electrode, 22 RF connection member, 30 Inner peripheral side resistance heating element, 32, 34 Terminal, 36, 38 Inner peripheral side connection Member, 40 outer resistance heating element, 42, 44 terminals, 46, 48 outer connecting member, L1 first annular layer, L2 second annular layer, W wafer, Zin inner zone, Zout outer zone.

Claims

An AlN ceramic substrate comprising yttrium aluminate,
Volume resistivity at 550 ° C. is 3 × 10 9 Ωcm or more,
AlN ceramic substrate.
The average particle diameter of the AlN sintered particles is 1.5 μm or more and 2.5 μm or less,
Yttrium aluminate exists in a dispersed state at the grain boundary between AlN sintered particles,
The AlN ceramic substrate of claim 1.
A resistance heating element is embedded in the AlN ceramic substrate according to claim 1 or 2,
Heater for semiconductor manufacturing equipment.
The resistance heating element is made of Mo,
The AlN ceramic substrate includes a first annular layer surrounding the resistance heating element so as to be in contact with the resistance heating element, and a second annular layer surrounding the first annular layer, wherein the first annular layer comprises: The Y content is larger and the layer width is wider than that of the second annular layer,
4. The heater for semiconductor manufacturing equipment according to claim 3.
the first annular layer continuously surrounds the resistive heating element;
the second annular layer continuously surrounds the first annular layer;
5. The heater for semiconductor manufacturing equipment according to claim 4.