JP2021015937A - Heating member - Google Patents

Abstract

To provide a technique for improving plasma resistance while also improving thermal uniformity on a placing surface, in a heating member.SOLUTION: A heating member comprises: a first member, mainly consisting of aluminum nitride, which has a placing surface that allows an object to be placed thereon and a rear surface that is on the opposite side in a first direction to the placing surface; a heater electrode part, disposed on the first member, which generates heat by the supply of power; and a second member, mainly consisting of aluminum nitride, which has a columnar shape extending in the first direction, and which is bonded to the rear surface of the first member. The porosity of the first member is lower than that of the second member.SELECTED DRAWING: Figure 1

Description

The present invention relates to a heating member.

Conventionally, a heating member for heating a semiconductor wafer has been known in the manufacturing process of a semiconductor device (for example, Patent Document 1).

Japanese Patent No. 4311910

In the semiconductor device manufacturing process, a plurality of semiconductor devices are manufactured from one semiconductor wafer mounted on the mounting surface of the heating member. Therefore, the heating member is required to improve the heat equalizing property of the mounting surface in order to suppress the variation in the characteristics of the semiconductor device. Further, since the heating member may be exposed to plasma, improvement in plasma resistance is also required. However, it has not been easy to achieve both improvement in heat equalization of the mounting surface and improvement in plasma resistance.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a technique for improving plasma resistance while improving heat equalization of a mounting surface in a heating member.

The present invention has been made to solve at least a part of the above-mentioned problems, and can be realized as the following forms.

(1) According to one embodiment of the present invention, a heating member is provided. This heating member is composed of a first member containing aluminum nitride as a main component and having a mounting surface on which an object can be mounted, and a back surface opposite to the previously described mounting surface in the first direction. A heater electrode portion that is arranged on the first member and generates heat by energization, and a second member that is mainly composed of aluminum nitride and has a columnar shape extending in the first direction and is joined to the back surface of the first member. The porosity of the first member is smaller than the porosity of the second member.

According to this configuration, the porosity of the first member on which the mounting surface on which the object can be placed is formed is smaller than the porosity of the second member joined to the back surface of the first member. When the object is etched by plasma, the etching by plasma proceeds from the pores on the surface of the heating member as well. In the heating member of the present invention, the porosity of the first member, which is easily irradiated with plasma, is made smaller than the porosity of the second member, so that the first member is less likely to be etched even when plasma is irradiated. Further, the second member having a porosity larger than that of the first member is less likely to transfer heat than the first member. As a result, it is possible to prevent the heat generated by the heater electrode portion arranged on the first member from escaping from the back surface of the first member through the second member to the first member, so that the heat equalization property of the first member can be improved. Can be improved. As a result, the plasma resistance can be improved while improving the heat soaking property of the mounting surface.

(2) In the heating member of the above embodiment, the average particle size of the aluminum nitride contained in the first member may be smaller than the average particle size of the aluminum nitride contained in the second member. According to this configuration, the porosity of the first member tends to be smaller than the porosity of the second member. As a result, the plasma resistance can be further improved while further improving the heat equalizing property of the mounting surface.

(3) In the heating member of the above embodiment, when the first member and the second member are plasma-etched, the surface roughness Ra of the first member becomes smaller than the surface roughness Ra of the second member. May be good. According to this configuration, the first member is less likely to be etched than the second member. As a result, the life of the heating member is extended, and the generation of particles due to etching is suppressed, so that contamination of the object by the particles can be suppressed.

(4) In the heating member of the above embodiment, the thermal conductivity of the first member may be larger than the thermal conductivity of the second member. According to this configuration, the heat generated by the heater electrode portion is easily transferred to the entire first member, so that the first member is easily heated evenly. Further, since the second member joined to the back surface of the first member has a lower thermal conductivity than the first member, the heat of the first member passes from the back surface of the first member to the first member through the second member. It is possible to suppress the escape from. As a result, the heat equalizing property of the first member can be further improved.

It is a perspective view of the heating member of 1st Embodiment. It is sectional drawing of the heating member of 1st Embodiment. It is a figure explaining the position which measures the characteristic of the 1st member and 2nd member. It is a figure which shows the measurement result of the characteristic of the 1st member and the 2nd member.

<First Embodiment>
FIG. 1 is a perspective view of the heating member 1 of the first embodiment. FIG. 2 is a cross-sectional view of the heating member 1 of the present embodiment. The heating member 1 of the present embodiment includes, for example, CVD (Chemical Vapor Deposition: Chemical Vapor Deposition), PVD (Physical Vapor Deposition), ALD (Atomic Layer Deposition), ALD (Atomic Layer Deposition). In the above, it is a ceramic heater used for heating the semiconductor wafer 3 as an “object”. The heating member 1 includes a first member 10, a second member 20, and a heater electrode portion 30.

The first member 10 is a circular plate-shaped member made of an oxide containing aluminum nitride and yttrium, and forms a mounting surface 11, a back surface 12, and an outer peripheral surface 13. The mounting surface 11 is formed on one main surface of the first member 10, and the semiconductor wafer 3 is mounted on the mounting surface 11. In the present embodiment, the area of the mounting surface 11 is the same as the area of the semiconductor wafer 3. The back surface 12 is formed on the main surface of the first member 10 opposite to the one main surface on which the mounting surface 11 is formed. The back surface 12 is joined to the second member 20. The outer peripheral surface 13 connects the mounting surface 11 and the back surface 12 at the outer peripheral portion 14 of the first member 10. In the present embodiment, the direction in which the straight line perpendicular to the back surface 12 extends is defined as the first direction.

The second member 20 is a columnar member made of aluminum nitride, and is formed in a hollow tubular shape having a ring-shaped cross section. The second member 20 is joined to the first member 10 in a state of extending in the first direction from the back surface 12 of the first member 10. Therefore, when the semiconductor wafer 3 mounted on the mounting surface 11 of the first member 10 is etched by plasma, the plasma does not easily reach the second member 20, so that the etching is difficult. The second member 20 is formed with a joint surface 21 for joining with the back surface 12 of the first member 10.

Comparing the first member 10 and the second member 20, the porosity of the first member 10 is smaller than the porosity of the second member 20. Further, the average particle size of the aluminum nitride contained in the first member 10 is smaller than the average particle size of the aluminum nitride contained in the second member 20, and the thermal conductivity of the first member 10 is larger than the thermal conductivity of the second member 20. large. Further, when the first member 10 and the second member 20 are plasma-etched, the surface roughness Ra of the first member 10 becomes smaller than the surface roughness Ra of the second member 20.

As shown in FIG. 2, the heater electrode portion 30 is a conductive member arranged inside the first member 10. The heater electrode portion 30 is connected to an external power source (not shown) via a power supply terminal 22 arranged inside the second member 20, and generates heat by energization. The heater electrode portion 30 has the same size as the mounting surface 11 or slightly larger than the mounting surface 11 so that the heat generated by energization can be evenly transferred to the semiconductor wafer 3 mounted on the mounting surface 11. It is formed to a size.

Next, a method of manufacturing the heating member 1 will be described. First, in manufacturing the first member 10, 100 parts by weight of aluminum nitride powder, 0.1 to 5 parts by weight of yttrium oxide (Y ₂ O ₃ ) powder, and a binder are mixed to prepare a mixture. Next, a molded body in which the heater electrode portion 30 is embedded in the above-mentioned mixture is produced, and the produced molded body is degreased and fired to produce the first member 10. The first member 10 can also be produced from a laminated body of green sheets or a cold isotropic pressure (CIP) of the granulated powder. When manufactured from a laminated body of green sheets, the heater electrode portion 30 is formed by printing a metal paste such as tungsten or molybdenum on the green sheet. Further, in the case of producing from granulated powder using CIP, the heater electrode portion 30 is formed by embedding a metal member. The firing may be normal pressure firing, hot press (HP), or hot isotropic press (HIP), but HP or HIP is desirable in order to reduce the number of pores in the first member 10.

The second member 20 is produced by degreasing and firing a molded product formed by mixing 100 parts by weight of aluminum nitride powder and a binder. At this time, in order to increase the number of pores in the second member 20, it is desirable not to include a sintering aid such as yttrium oxide as the material of the molded product. The molded body of the second member 20 can also be produced from a cold isotropically pressurized granulated powder. The firing may be any of normal pressure firing, hot pressing, and hot isotropic pressing, but normal pressure firing is desirable in order to increase the number of pores in the second member 20.

As described above, in the heating member 1 of the present embodiment, when the first member 10 is manufactured, yttrium oxide powder is added to the material as a sintering aid, so that sintering can easily proceed and the porosity Is easy to get smaller. On the other hand, when the second member 20 is manufactured, since the sintering aid is not added, it is necessary to perform sintering at a high temperature for a long time in order to sinter, and crystal grains tend to grow. Further, comparing the sintering of the first member 10 and the second member 20, the second member 20 tends to have a higher porosity than the first member 10 to which the sintering aid is added because the sintering does not proceed easily. .. As described above, the porosity of the first member 10 and the second member 20 can be changed depending on the amount of the sintering aid added and the sintering conditions.

Finally, the first member 10 including the heater electrode portion 30 and the second member 20 are joined. Specifically, the surface roughness Ra of the joint surface 21 of the back surface 12 of the first member 10 and the second member 20 is set to 1 μm or less and the flatness is set to 10 μm or less by, for example, lap polishing or rotary polishing. The first member 10 and the second member 20 are joined by applying a load to the back surface 12 of the polished first member 10 and the joint surface 21 of the second member 20 and performing heat treatment at a firing temperature or lower. .. At this time, a bonding material composed of an oxide containing rare earths or the like may be interposed in the bonding surface 21, whereby the first member 10 and the second member 20 can be precisely bonded.

Next, the difference in characteristics between the first member 10 and the second member 20 will be described. In the present embodiment, the characteristics of the first member 10 and the second member 20 are measured by using the measuring portion and the measuring method described below.

FIG. 3 is a diagram illustrating positions for measuring the characteristics of the first member 10 and the second member 20. FIG. 4 is a diagram showing measurement results of the characteristics of the first member 10 and the second member 20. In the enlarged cross-sectional view of the heating member 1 shown in FIG. 3, the heater electrode portion 30 is not shown for convenience of explanation. The characteristics of the internal regions A11, A12, and A13 of the first member 10 shown in FIG. 3 (a) and the internal regions A21 and A22 of the second member 20 shown in FIG. 3 (b) were measured in each member. It shows the approximate position of the part. Further, as a reference value, FIG. 4 shows a theoretical density ratio showing the ratio of the sintered body density measured by the Archimedes method to the theoretical density. Here, the theoretical density refers to the density calculated by the mixing law from the content of each oxide by converting the content of each element component constituting the sintered body into an oxide. In the present embodiment, the characteristics of each of the first member 10 and the second member 20 are the porosity, the average particle size of the aluminum nitride particles, the surface roughness Ra after plasma irradiation, the etching depth by plasma, and the heat. The conductivity was measured.

(Porosity)
Measurement part 1st member 10: Located within 0.5 mm in the depth direction of the first member 10 from the mounting surface 11 and within 1 mm in the direction from the outer peripheral surface 13 toward the inside of the 1st member 10. (Region A11 shown in FIG. 3A)
Second member 20: A portion located between the joint surface 21 and the second member 20 in the depth direction of 2 mm or more and 4 mm or less (region A21 shown in FIG. 3B).
-Measuring method It was calculated from (pore area) / (total area) using an SEM photograph (see the SEM photograph of FIG. 4) of the above-mentioned measurement portion mirror-polished without bleaching at a magnification of 1000 times.

(Average particle size of aluminum nitride particles)
Measurement part 1st member 10: Located within 0.5 mm in the depth direction of the first member 10 from the mounting surface 11 and within 1 mm in the direction from the outer peripheral surface 13 toward the inside of the 1st member 10. (Region A11 shown in FIG. 3A)
Second member 20: A portion located between the joint surface 21 and the second member 20 in the depth direction of 2 mm or more and 4 mm or less (region A21 shown in FIG. 3B).
-Measuring method Using an SEM photograph (see FIG. 4) at a magnification of 1000 times of the above-mentioned measured portion after mirror polishing and thermal etching, 50 or more particles were counted by the intercept method, and the obtained average section length was obtained. It was calculated by multiplying this by a coefficient of 1.5.

(Surface condition after plasma etching)
Measurement part 1st member 10: Located within 0.5 mm in the depth direction of the first member 10 from the mounting surface 11 and within 1 mm in the direction from the outer peripheral surface 13 toward the inside of the 1st member 10. Part including the range to be used (region A12 shown in FIG. 3A)
Second member 20: A portion located between the joint surface 21 and the second member 20 in the depth direction of 2 mm or more and 30 mm or less (region A22 shown in FIG. 3B).
-Measurement method In this measurement, a plasma exposure experiment was conducted in which the above-mentioned measured portion whose surface roughness Ra was 0.1 μm due to mirror polishing was plasma-etched to a depth equal to or larger than the average particle size using etching gas CF _4. , The surface roughness Ra of the test sample after the plasma exposure experiment was measured. The surface roughness Ra is a value specified by JISB0601-2013. The etching depth was measured using a contact type shape measuring device.

(Thermal conductivity)
-Measuring part 1st member 10: A part including a range located within 1 mm in the direction from the outer peripheral surface 13 toward the inside of the 1st member 10 (region A13 shown in FIG. 3A).
Second member 20: The same portion as the range for evaluating the surface state after plasma etching (region A22 shown in FIG. 3A).
The regions A13 and A22 do not include the heater electrode portion 30, the tunnel, the gas hole, and the like.
-Measurement method Measured by laser flash method.

As described above, the outer peripheral portion 14 in the vicinity of the outer peripheral surface 13 is selected as the portion for measuring the characteristics of the first member 10. The reason for this is that the outer peripheral surface 13 is easily irradiated with plasma and may be plasma-etched. Further, since the outer peripheral portion 14 is close to the outer peripheral portion of the semiconductor wafer 3 mounted on the mounting surface 11, plasma is easily irradiated.

From the evaluation results of the first member 10 and the second member 20 shown in FIG. 4, the porosity of the first member 10 (0.154%) is smaller than that of the second member 20 (0.424%), and the difference is , 0.1% or more was revealed. Further, it was revealed that the average particle size of the aluminum nitride particles was smaller in the first member 10 (7.1 μm) than in the second member 20 (9.9 μm), and the difference was 1 μm or more. Comparing the first member 10 and the second member 20, the porosity of the first member 10 is higher because the average particle size of the aluminum nitride particles of the first member 10 is smaller than the average particle size of the aluminum nitride particles of the second member 20. It can be seen that the porosity of the second member 20 is smaller than that of the second member 20.

Further, as shown in FIG. 4, in the surface state after plasma etching, the surface roughness Ra of the first member 10 is 138.7 μm, and the etching depth is 8.3 μm. On the other hand, the surface roughness Ra of the second member 20 is 172.7 μm. From this, the surface roughness Ra of the first member 10 after plasma etching is 90% or less of the surface roughness Ra of the second member 20, which is smaller than the surface roughness Ra of the second member 20. You can see that there is. Further, the etching depth of the second member 20 is 10.1 μm, and when the first member 10 and the second member 20 are compared, the first member 10 has pores that are the starting points of etching by plasma. Since it is less than 2 members 20, it can be seen that etching by plasma is difficult to proceed. When the semiconductor wafer 3 on the heating member 1 is etched by plasma, the second member 20 is located on the side opposite to the side irradiated with plasma, so that there are many pores that are the starting points of etching by plasma. However, it is difficult to etch.

Further, in terms of thermal conductivity, the first member 10 (119.2 W / m · K) is larger than the second member 20 (91.5 W / m · K), and the difference is 5 W / m · K or more. It became clear. As a result, the heat generated by the heater electrode portion 30 is easily transferred to the entire first member 10, and the first member 10 is easily heated evenly. Further, the heat of the first member 10 is difficult to escape from the first member 10 through the second member 20.

According to the heating member 1 of the present embodiment described above, the porosity of the first member 10 on which the mounting surface 11 on which the semiconductor wafer 3 can be mounted is formed is smaller than the porosity of the second member 20. .. When the semiconductor wafer 3 mounted on the mounting surface 11 is etched by plasma, the etching by plasma proceeds in the heating member 1 starting from the pores on the surface. The heating member 1 of the present embodiment is less likely to be etched even if it is irradiated with plasma by making the porosity of the first member 10 that is easily irradiated with plasma smaller than the porosity of the second member 20. Further, the second member 20 having a porosity larger than that of the first member 10 is less likely to transfer heat than the first member 10. As a result, it is possible to prevent heat generated by the heater electrode portion 30 arranged on the first member 10 from escaping from the back surface 12 of the first member 10 through the second member 20 and from the first member 10. The heat equalizing property of one member 10 can be improved. Therefore, the plasma resistance can be improved while improving the heat soaking property of the mounting surface 11.

Further, according to the heating member 1 of the present embodiment, the average particle size of the aluminum nitride contained in the first member 10 is smaller than the average particle size of the aluminum nitride contained in the second member 20. As a result, the porosity of the first member 10 tends to be smaller than the porosity of the second member 20. Therefore, the plasma resistance can be further improved while further improving the heat equalizing property of the mounting surface 11. Further, the plasma resistance can be further improved by the small average particle size itself.

Further, according to the heating member 1 of the present embodiment, when the first member 10 and the second member 20 are plasma-etched, the surface roughness Ra of the first member 10 is higher than the surface roughness Ra of the second member 20. It becomes smaller. That is, the first member 10 is less likely to be etched than the second member 20. As a result, the life of the heating member 1 is extended, and the generation of particles due to etching is suppressed, so that the contamination of the semiconductor wafer 3 by the particles can be suppressed.

Further, according to the heating member 1 of the present embodiment, the thermal conductivity of the first member 10 is larger than the thermal conductivity of the second member 20. As a result, the heat generated by the heater electrode portion 30 is easily transferred to the entire first member 10, and the first member 10 is easily heated evenly. Further, since the second member 20 joined to the back surface 12 of the first member 10 has a lower thermal conductivity than the first member 10, the heat of the first member 10 is transferred from the back surface 12 to the second member 10 of the first member 10. It is possible to suppress the escape from the first member 10 through the member 20. As a result, the heat equalizing property of the first member 10 can be further improved.

<Modified example of this embodiment>
The present invention is not limited to the above-described embodiment, and can be implemented in various aspects without departing from the gist thereof. For example, the following modifications are also possible.

[Modification 1]
In the above embodiment, it is assumed that the first member 10 is formed of an oxide containing aluminum nitride and yttrium. However, the first member 10 may contain a material other than the oxide containing aluminum nitride and yttrium, and may contain aluminum nitride as a main component.

[Modification 2]
In the above-described embodiment, the average particle size of the aluminum nitride contained in the first member 10 is smaller than the average particle size of the aluminum nitride contained in the second member 20. However, the magnitude relationship of the average particle size of aluminum nitride is not limited to this.

[Modification 3]
In the above-described embodiment, when the first member 10 and the second member 20 are plasma-etched, the surface roughness Ra of the first member 10 is smaller than the surface roughness Ra of the second member 20. However, the magnitude relationship of the surface roughness Ra is not limited to this. In particular, when the first member 10 and the second member 20 are plasma-etched, if the surface roughness Ra of the first member 10 is 2/3 or less of the surface roughness Ra of the second member 20, the life of the heating member 1 is reached. Can be further extended, and contamination of the semiconductor wafer 3 by particles can be further suppressed.

[Modification example 4]
In the above-described embodiment, the thermal conductivity of the first member 10 is larger than the thermal conductivity of the second member 20. However, the magnitude relationship of thermal conductivity is not limited to this.

[Modification 5]
In the above-described embodiment, the area of the mounting surface 11 is the same as the area of the semiconductor wafer 3 mounted on the mounting surface 11. However, the relationship between the area of the mounting surface 11 and the area of the semiconductor wafer 3 is not limited to this. For example, when the area of the mounting surface 11 is larger than the area of the semiconductor wafer 3 and the semiconductor wafer 3 is mounted on the mounting surface 11, the outer peripheral portion of the mounting surface 11 may be exposed.

Although the present embodiment has been described above based on the embodiments and modifications, the embodiments of the above-described embodiments are for facilitating the understanding of the present embodiment, and do not limit the present embodiment. This aspect may be modified or improved without departing from its spirit and claims, and this aspect includes its equivalents. In addition, if the technical feature is not described as essential in the present specification, it may be deleted as appropriate.

1 ... Heating member 3 ... Semiconductor wafer 10 ... First member 11 ... Mounting surface 12 ... Back surface 13 ... Outer peripheral surface 14 ... Outer peripheral part 20 ... Second member 21 ... Joint surface 22 ... Power supply terminal 30 ... Heater electrode parts A11, A12 , A13, A21, A22 ... Area

Claims (4)

It is a heating member
A first member containing aluminum nitride as a main component and having a mounting surface on which an object can be mounted and a back surface opposite to the previously described mounting surface in the first direction.
A heater electrode portion that is arranged in the first member and generates heat when energized,
It is provided with a second member having aluminum nitride as a main component, which is a columnar shape extending in the first direction and is joined to the back surface of the first member.
The porosity of the first member is smaller than the porosity of the second member.
Heating member. The heating member according to claim 1.
The average particle size of aluminum nitride contained in the first member is smaller than the average particle size of aluminum nitride contained in the second member.
Heating member. The heating member according to claim 1 or 2.
When the first member and the second member are plasma-etched, the surface roughness Ra of the first member is smaller than the surface roughness Ra of the second member.
Heating member. The heating member according to any one of claims 1 to 3.
The thermal conductivity of the first member is larger than the thermal conductivity of the second member.
Heating member.