JP2000049217A - Wafer holding member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer holding member which is free from breaking of a board-like ceramic body, even when it is heated up repeatedly to a high temperature above 550 deg.C, and free of anomalous heating or disconnection of an inner electrode due to exfoliation of the brazing material. SOLUTION: The upper face of a board-like ceramic body 2, in which an inner electrode 4 is embedded, is used as a loading plane for a wafer W, and on the lower surface of the board-like ceramic body 2, a lower hole 2a is provided for the inner electrode 4 to penetrate. Meanwhile, a recess 5a is prepared on a feed terminal 5 at its jointing end, and a stress-relaxing material member 8 is inserted into the recess 5a, where the stress-relaxing material member 8 has a thermal expansion coefficient difference which is not more than +2.9×10-6/ deg.C as compared with that of the board-like ceramic body 2 and has a protrusion 8b partially protruding from the jointing side edge of the feed terminal 5. Then, the feed terminal 5 is inserted into the lower hole 2a and is brazed to the lower hole 2a of the board-like ceramic body 2. The protruding part 8b of the stress-relaxing material member 8 and the exposed part 4a of the inner electrode 4 at the lower hole 2a are brazed to each other, to be fastened to constitute a wafer holding member 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to sputtering,
The present invention relates to a wafer support member such as a susceptor or an electrostatic chuck for supporting a wafer such as a semiconductor wafer used for a film forming apparatus such as PVD or CVD or an etching apparatus.

[0002]

2. Description of the Related Art Conventionally, sputtering, PVD, plasma CVD, reduced pressure CVD,
2. Description of the Related Art In a film forming apparatus such as an optical CVD or an etching apparatus such as a plasma etching or an optical etching, a wafer supporting member such as a susceptor or an electrostatic chuck is used to support a semiconductor wafer.

For example, a wafer support member 21 shown in FIG. 7 is a susceptor with a built-in heater, which is formed of a disc-shaped plate-like ceramic body 22, and the upper surface of which is placed on the mounting surface 2 of the semiconductor wafer W.
3, and a metal power supply terminal 25 formed by embedding an internal electrode 24 for a heater electrode therein and being brazed and fixed to a prepared hole 22a formed in the lower surface of the plate-shaped ceramic body 22. The internal electrode 24 is energized through the switch.

A wafer support member 31 shown in FIG. 8 is an electrostatic chuck with a built-in heater and is made of a disc-shaped plate-like ceramic body 32. An internal electrode 36 for electrostatic adsorption is embedded on the mounting surface 33 side of the mounting surface 33, and an internal electrode 34 for a heater electrode is embedded on the opposite side to the mounting surface 33, respectively.
A pilot hole 32 formed in the lower surface of the plate-like ceramic body 33
a, power supply terminal 3 made of metal and fixed to brazing portions 32a and 32b
Electric current is supplied to the respective internal electrodes 34 and 36 via the reference numerals 5 and 37.

The power supply terminals 25, 35 and 37 of the wafer support members 21 and 31 shown in FIGS. 7 and 8 each have an outer diameter of 2 to alleviate residual stress during brazing.
A solid cylinder having a diameter of about 15 mm is used, and prepared holes 22a, 32a, 32
b was perforated through the internal electrodes 24, 34 and 36, respectively.

[0006]

By the way, in the film forming apparatus and the etching apparatus, the internal electrodes 24 and 34 of the wafer supporting members 21 and 31 shown in FIGS.
Various processes are performed in a state where the semiconductor wafer W is heated to a high temperature of about 300 ° C., and further, about 500 ° C., but a heat cycle is applied to the wafer support members 21 and 31 in a range from room temperature to various processing temperatures. Become.

[0007] When a thermal cycle in such a temperature range is repeatedly applied, thermal stress caused by a difference in thermal expansion between the power supply terminals 25, 35, 37 and the plate-like ceramic bodies 22, 32 causes a thermal stress in the pilot holes 22a, 22a. There is a problem that cracks occur in the plate-like ceramic bodies 22 and 32 due to concentration on the bases 32a and 32b and the wafer support members 21 and 31 are damaged.

Accordingly, the applicant of the present application has shown in FIG.
A concave portion 45a is provided on an end surface on the joining side of the power supply terminal 45, and the plate-like ceramic body 22 (32) is formed in the concave portion 45a.
By inserting a ceramic stress relaxation material 48 having the same thermal expansion coefficient as that of the power supply terminal 45, deformation of the power supply terminal 45 due to thermal expansion is restricted by the plate-like ceramic body 22 (32) and the stress relaxation material 48. As well as the pilot hole 22a (32a,
It has been previously proposed to alleviate the thermal stress concentrated on 32b) and prevent breakage of the plate-like ceramic body 22 (32).

However, in recent years, the diversification of film material for forming the semiconductor wafer W, other than W film which has been used so far, Ti film, become SiO ₂ film, such as WSi _X film is used The processing temperature has been 5
What has been required to be formed at a processing temperature of 550 ° C. to 900 ° C. from what was about 00 ° C. is required. Even if the structure shown in the figure is adopted, the thermal stress caused by the difference in thermal expansion between the plate-like ceramic body 22 (32) and the power supply terminal 45 cannot be sufficiently reduced, and the brazing material q becomes the plate-like ceramic body 22 (32). ) Prepared hole 22a (32a, 3
2b), the resistance value of the portion was partially increased, and there was a result that local abnormal heat generation occurred at the portion where the brazing material q was separated. In particular, if peeling of the brazing material q occurs between the internal electrodes 24 (34, 36) exposed in the prepared holes 22a (32a, 32b), the internal electrodes 24 (34, 36) are disconnected due to abnormal heat generation. there were.

[0010]

In view of the above-mentioned problems, the present invention has been made in consideration of the above-mentioned problems, and has an upper surface of a plate-like ceramic body in which internal electrodes are buried as a mounting surface of a wafer, and a lower surface of the above-mentioned plate-like ceramic body. In a wafer supporting member having a pilot hole penetrating an electrode, and a power supply terminal being brazed to the pilot hole, a concave portion is provided on an end surface on the joining side of the power supply terminal, and the concave portion has a thermal conductivity with the plate-shaped ceramic body. A stress relaxation material having a difference in expansion of not more than + 2.9 × 10 ⁻⁶ / ° C. and having a protruding part partially protruding from the end face of the power supply terminal on the joining side is inserted and the power supply terminal is connected to the plate-shaped ceramic body. And the brazing and fixing of the projecting portion of the stress relieving material to the exposed portion of the internal electrode exposed from the prepared hole.

Further, the present invention makes the distance from the entrance of the pilot hole drilled in the plate-shaped ceramic body to the front end surface of the stress relaxation material 3 mm or less, thereby preventing breakage at the entrance hole of the plate-shaped ceramic body. It is like that.

Further, according to the present invention, the stress relaxation material is formed of insulating ceramics, and a conductor layer is buried therein, so that a part of the conductor layer is exposed from a side surface of the protrusion. In addition, when a large current flows, the vicinity of the internal electrode exposed in the prepared hole is suppressed from locally generating heat, and the temperature of the mounting surface is prevented from fluctuating.

Further, according to the present invention, an Au-N
By coating with an i-type brazing material, the oxidation resistance of the power supply terminal is improved.

[0014]

According to the wafer support member of the present invention, the thickness of the thin portion constituting the concave portion is made as small as possible by providing the concave portion on the end face on the joining side of the power supply terminal, and the thermal expansion difference between the thin plate portion and the plate-shaped ceramic body is reduced. Since the thermal stress accompanying the above can be reduced, cracking of the plate-shaped ceramic body can be prevented. Further, a stress relaxation material having a thermal expansion difference of + 2.9 × 10 ⁻⁶ / ° C. or less with respect to the plate-shaped ceramic body is inserted into the concave portion of the power supply terminal, and the thin portion of the power supply terminal is stressed with the plate-shaped ceramic body. Since the power supply terminal is sandwiched by the cushioning material, it is possible to prevent the conduction failure due to the deformation of the power supply terminal as much as possible.

Further, the stress relieving material is provided with a protruding portion which partially protrudes from the end face on the joining side of the power supply terminal, and this protruding portion and the exposed portion of the internal electrode exposed in the prepared hole of the plate-shaped ceramic body are connected. Since the wafer support member is directly fixed by brazing, even if the wafer support member is heated to a high temperature of 550 ° C. or more, the thermal stress applied to the exposed portion of the internal electrode is small. Will not occur. Therefore, there is no local abnormal heat generation in the exposed portion of the internal electrode, and there is no disconnection of the internal electrode.

[0016]

Embodiments of the present invention will be described below. FIGS. 1A and 1B are views showing an example in which the wafer supporting member of the present invention is used as a susceptor with a built-in heater, wherein FIG. 1A is a perspective view thereof, and FIG.

The wafer support member 1 is composed of a disk-shaped plate-like ceramic body 2 and the upper surface thereof is
And an internal electrode 4 for a heater electrode embedded therein, and two lower holes 2a penetrating the internal electrode 4 on the lower surface of the plate-shaped ceramic body 2.
The internal electrode 4 is energized through a power supply terminal 5 brazed and fixed to these two prepared holes 2a. In order to operate the wafer support member 1, the semiconductor wafer W is heated at a predetermined processing temperature by heating the wafer support member 1 by energizing the internal electrode 4 while the semiconductor wafer W is mounted on the mounting surface 3. To be heated.

On the other hand, FIG. 2 is a view showing an example in which the wafer support member of the present invention is used as an electrostatic chuck with a built-in heater, (a) is a perspective view thereof, and (b) is a sectional view taken along line YY. is there.

The wafer support member 11 is made of a disk-shaped plate-like ceramic body 12, and its upper surface is used as a mounting surface 13 for the semiconductor wafer W, and is used for electrostatic attraction on the inner mounting surface 13 side. And an internal electrode 14 for a heater electrode is buried on the opposite side of the mounting surface 13, and one lower hole penetrating the internal electrode 16 is formed on the lower surface of the plate-shaped ceramic body 12. 12b and two pilot holes 12a penetrating the internal electrode 14 are respectively formed. Electric current is supplied to the internal electrodes 14 and 15 via power supply terminals 15 and 17 fixed to the pilot holes 12a and 12b by brazing. It is like that. To operate the wafer support member 11, the semiconductor wafer W is placed on the mounting surface 13
And a current is applied between the semiconductor wafer W and the internal electrode 16 so that Coulomb force due to dielectric polarization and Johnson-Rahbek force due to a small leakage current are developed.
Is fixed to the mounting surface 13 by suction, and in this state, the internal electrode 14 is energized to heat the wafer support member 11, thereby heating the semiconductor wafer W to a predetermined processing temperature.

As a material of the plate-like ceramic bodies 2 and 12 constituting the wafer support members 1 and 11, a ceramic mainly containing any one of alumina, aluminum nitride and silicon nitride can be used. Among these, alumina (Al ₂ O ₃ ) as a main component, silica (SiO ₂ ), magnesia (MgO), and calcia (C
and alumina ceramics containing a sintering aid such as aO-) in the range of 1 wt% or less, the alumina content of the main component 99.8% by weight or more of high-purity alumina ceramics or aluminum nitride,, Y ₂ O ₃ Or Er ₂ O ₃
Aluminum nitride ceramics containing an oxide of a rare earth element such as 1 to 9% by weight, and high-purity aluminum nitride ceramics having an aluminum nitride content of 99.8% by weight or more are formed by a film forming apparatus or an etching method. It is suitable because it has excellent corrosion resistance to fluorine-based and chlorine-based halogen-based gases used as a deposition gas, an etching gas, or a cleaning gas in an apparatus and the like, and also has excellent plasma resistance. .

The material of the internal electrodes 4, 14, 16 embedded in the plate-like ceramic bodies 2, 12 is a high melting point metal such as tungsten (W), molybdenum (Mo), rhenium (Re), and platinum (Pt). Or alloys thereof, or tungsten carbide (WC) or titanium nitride (TiN)
For example, carbides or nitrides of elements of Groups 4a, 5a, and 6a of the periodic table can be used.

The shape of the plate-shaped ceramic bodies 2 and 12 is not limited to a disk shape, but may be any shape such as a polygonal shape such as a square or a hexagon or an elliptical shape. The internal electrodes 4, 14, 16 embedded in the plate-shaped ceramic bodies 2, 12 may be in the form of a film or a wire by means such as printing.

By the way, in the wafer support members 1 and 11 shown in FIGS. 1 and 2, the joining of the power supply terminals 5, 15 and 17 to the plate-like ceramic bodies 2 and 12 is performed, for example, in a columnar shape as shown in FIG. A concave portion 5a (15a, 17) having a circular cross section
a), and a thermal expansion difference of + 2.9 × 10 between the plate-shaped ceramic bodies 2 and 12 is provided in the concave portions 5a (15a and 17a).
^The stress relaxation member 8 (18, 19) having a protrusion 8b (18b, 19b) projecting from the end face on the joining side of the power supply terminal 5 (15, 17) at a temperature not higher than ^-6 / ° C. is inserted. The projecting portion 8b (18b, 18b) of the stress relaxation member 8 (18, 19)
19b) has substantially the same diameter as the outer diameter of the power supply terminal 5 (15, 17), and the tip 8a (18a, 19a) has a smaller diameter than the protrusion 8b (18b, 19b) and the power supply terminal 5 (1).
(5, 17) are formed so as to engage with the concave portions 5a (15a, 17a).

Then, as shown in FIG. 4, a brazing material q is applied to the inner wall surfaces of the pilot holes 2a (12a, 12b) of the plate-shaped ceramic bodies 2, 12, and the stress relaxing members 8 (18, 1) are applied.
After inserting the power supply terminal 5 (15, 17) into which the power supply terminal 9 (9) is inserted, heat treatment is applied and brazing is fixed. At this time, the pilot hole 2a (12a, 12b) and the power supply terminal 5 (15, 17) are fixed.
17), and the lower hole 2a (12)
a, 12b) and the exposed portions 4a (14a, 16a) of the internal electrodes 4 (14, 16) and the stress relaxation members 8 (18, 18).
Also, the projection 8b (18b, 19b) of 19) is brazed and fixed.

As described above, by providing the concave portion 5a (15a, 17a) on the end face on the joining side of the power supply terminal 5 (15, 17), the thin portion 5b (15b, 17b) constituting the concave portion 5a (15a, 17a) is provided. ) Can be reduced, so that even if thermal stress due to the difference in thermal expansion is applied to the plate-shaped ceramic bodies 2 and 12 due to repetition of heating and cooling, the thermal stress is reduced and the plate-shaped ceramic Body 2,1
2 can be prevented.

The power supply terminal 5 (15, 17) has a concave 5
a (15a, 17a) alone, the power supply terminal 5
When the thin portion 5b (15b, 17b) of (15, 17) is deformed inward, the brazing material q is peeled off, which may cause a conductor failure. However, the concave portion 5a of the power supply terminal 5 (15, 17) may be formed. 15a, 17a), the stress relaxation members 8 (18, 19) having a thermal expansion difference of + 2.9 × 10 ⁻⁶ / ° C. or less with respect to the plate-shaped ceramic bodies 2 and 12 are inserted. , The thin portion 5b (15b, 15b) of the power supply terminal 5 (15, 17).
17b) attempts to deform the plate-shaped ceramic body 2,
12 and the stress relieving material 8 (18, 19) can be held and restrained, so that occurrence of poor conduction can be suppressed as much as possible.

Further, when the processing temperature becomes 550 ° C. or more, the concave portion 5a (15a, 1) of the power supply terminal 5 (15, 17) is formed.
7a), the plate-shaped ceramic bodies 2 and 12 and the power supply terminals 5 (1
5, 17) cannot sufficiently be relieved, and as a result, the brazing material q is not formed in the prepared holes 2a (12a, 12a).
The resistance value is partially increased by peeling off from b) and abnormal heat is locally generated. In particular, the thin internal electrode 4 (14, 1
When peeling of the brazing material q occurs at the exposed portions 4a (14a, 16a) of 6), the internal electrodes 4 (14, 1) are caused by abnormal heat generation.
6), the internal electrodes 4, 14, 16
The exposed portions 4a (14a, 16a) of the stress relief members 8 having a thermal expansion coefficient similar to those of the plate-shaped ceramic bodies 2 and 12 are formed.
The internal electrodes 4 (14, 16) are formed by directly brazing to the protruding portions 8b (18b, 19b) of the (18, 19) without the power supply terminals 5 (15, 17) interposed therebetween.
The thermal stress applied to the exposed portion 4a (14a, 16a) can be further reduced, and the peeling of the brazing material q at the exposed portion 4a (14a, 16a) can be prevented. Therefore, the internal electrode 4
There is no local abnormal heat generation in the exposed portions 4a (14a, 16a) of (14, 16), and the internal electrodes 4
550 ° C to prevent disconnection of (14,16)
Even in the above temperature range, stable conduction can always be achieved. The thin portion 5b (1) of the power supply terminal 5 (15, 17)
5b, 17b) is too thick, the effect of relaxing the thermal stress is small.
The diameter L is preferably 0.2 times or less of the diameter L of 7).

Further, it is preferable that the tip 8a (18a, 19a) of the stress relaxation member 8 (18, 19) be as long as possible. That is, the tip 8a (18a, 19a) of the stress relaxation member 8 (18, 19) is
2) In the state where it is in the prepared hole 2a (12a, 12b),
This is because thermal stress acting on the entrance of the pilot hole 2a (12a, 12b) is increased, which may cause cracks and breakage. The distance L to the front end surface of 18, 19) is 3
mm or less, preferably the front end portion 8a (18a, 19a) of the stress relaxation material 8 (18, 19) is formed in the prepared hole 2a (12a, 12a).
It is good to constitute so that it may protrude from b).

However, even in the structure shown in FIG. 4, the plate-like ceramics 2 and 2 are used as the stress relaxation members 8 (18, 19).
With those thermal expansion difference between the 12 is greater than + 2.9 × 10 ^-6 / ℃, during cooling after brazing or immediately after energization, the stress relaxation member 8 (18, 19) and the feeding terminal 5 (1
5, 17) and the thin portion 5b (15b, 17b) of the power supply terminal 5 (15, 17) contracts.
Since the effect of restraining 17b) from deforming inward is reduced, the brazing material q may peel off, causing local abnormal heat generation.

Therefore, the stress relaxation member 8 (18, 19) has a thermal expansion difference of + 2.9 × from the plate-like ceramic body 2 (12).
It must be formed of a material having a temperature of 10 ⁻⁶ / ° C. or less.
Here, the difference in thermal expansion between the plate-shaped ceramic body 2 (12) and + 2.9 × 10 ⁻⁶ / ° C. or less means that the stress relaxation member 8 (18, 19) has a coefficient of thermal expansion of plate-shaped ceramic. Body 2
It is smaller than the value obtained by adding 2.9 × 10 ⁻⁶ / ° C. to the thermal expansion coefficient of (12). As such a material, as in the case of the plate-shaped ceramic body 2 (12), a ceramic or a cemented carbide mainly containing any one of alumina, aluminum nitride, and silicon nitride can be used. Ceramics having the same main components as the body 2 (12), preferably ceramics having the same composition as the plate-like ceramic body 2 (12), may be used.

Incidentally, stainless steel, inconel, nickel, Fe-Ni-Co alloy, Fe-Ni alloy can be used as a material for forming the power supply terminal 5 (15, 17), and particularly, oxidation resistance is required. If
By covering the power supply terminals 5 (15, 17) with the Au-Ni-based brazing material, the durability can be improved. 3 and 4, the power supply terminal 5 (15, 17) has a circular outer shape. However, the present invention is not limited to this, and the power supply terminal 5 (15, 17) may have a polygonal shape such as a square or a triangle, or an elliptical shape.
Further, any external shape such as a semicircular shape may be used.

As the brazing material q for joining the plate-shaped ceramic body 2 (12) and the power supply terminal 5 (15, 17),
It is necessary to use a material that does not melt and liquefy in a high temperature range,
Ag-Cu or Ti-Cu-Ag brazing material q, 60
When used in a high temperature range of 0 ° C or higher, Au-Ni-
V-based brazing material q is preferable because of its excellent oxidation resistance.

Next, an application example of the present invention will be described.

FIG. 5 is an enlarged cross-sectional view of the junction of the power supply terminals when the internal electrodes for plasma generation are embedded in the wafer support members 1 and 11 shown in FIGS. 1 and 2. FIG.
FIG. 5 is a perspective view showing a stress relieving material 58 used in the first embodiment, which basically has the same structure as that of FIG.
8 and a conductor layer 59 is buried in the conductor layer 5.
9 is partially exposed from the side surface of the protruding portion 58b and the side surface of the tip portion 58a. Then, the protrusion 58b
Conductor layer 59 exposed from the side surface of
(12) The internal electrode 54 for plasma generation exposed in the pilot hole 52a is brazed and fixed.

That is, when generating a plasma, it is necessary to flow a large current of about 30 amps to the power supply terminal 55. However, when such a large current is supplied to the structure shown in FIG. Although current does not flow until the internal electrode 54 is disconnected, the mounting surfaces 3 and 13 cannot be uniformly heated due to abnormal heat generation.
On the other hand, as shown in FIG. 6, a conductor layer 59 is buried in the stress relieving material 58, and a part thereof is exposed from the side surface of the protruding portion 58b and is brought into contact with the brazing material q, whereby the stress relieving material 5 is formed.
8, a current can be applied to the internal electrode 54 through the conductor layer 59, thereby suppressing abnormal heat generation at this junction.
The temperature distribution on the mounting surfaces 3 and 13 can be made uniform.

(Embodiment) The wafer support member 1 made of aluminum nitride ceramic shown in FIG. 1 will be specifically described below as an example.

A binder and a solvent are added to and mixed with aluminum nitride powder having a purity of 99.9% to form a slurry.
A plurality of green sheets were manufactured by the doctor blade method. After stacking several green sheets among them, laying a conductor paste to be the internal electrode 4 in a predetermined pattern shape by a screen printing machine, and then stacking the remaining green sheets so as to cover the above pattern, and performing thermocompression bonding. Then, a green sheet laminated body was manufactured by integrating them. Then, after cutting the green sheet laminate to form a disk shape, the green sheet laminate is subjected to a process in a nitrogen atmosphere.
By firing at a temperature of about 2100 ° C., the internal electrode 4 as a heater electrode is buried and has a diameter of about 200 m.
m, disk-shaped plate-shaped ceramic body 2 with a thickness of about 15 mm
I got Further, aluminum nitride ceramics fired by the same method is used for ICP-AES (Inductively Coupling).
Measurement by led Plasma Atomic Emission Spectroscopy) revealed that the sample was composed of high-purity aluminum nitride ceramics having an aluminum nitride content of 99.8% by weight.

Next, one main surface of the obtained plate-shaped ceramic body 2 is polished to form a mounting surface 3 for the semiconductor wafer W, and the other main surface of the plate-shaped ceramic body 2 is drilled. Thus, two pilot holes 2a penetrating the internal electrode 4 were formed, and a brazing material q was applied to the inner wall surface of the pilot hole 2a. It should be noted that Au (82% by weight) -Ni (18% by weight) -V (3% by weight) based brazing material q was used.

On the other hand, the pilot hole 2a of the plate-shaped ceramic body 2
A power supply terminal 5 made of a Fe-Co-Ni alloy and a high-purity aluminum nitride ceramic having the same composition as the plate-shaped ceramic body 2 are formed.
After preparing a stress relief material 8 in which the b and the protruding portion 8a are integrally formed, forming a concave portion 5a on one end surface of the power supply terminal 5, the distal end portion 8b of the stress relief material 8 is placed in the concave portion 5a. The inserted power supply terminal 5 is inserted into the prepared hole 2a of the plate-shaped ceramic body 2, and the projection 8a of the stress relaxation material 8 is aligned with the exposed portion 4a of the internal electrode 4 exposed to the prepared hole 2a.
By applying heat treatment for 10 minutes in a vacuum of 10 ^-5 torr at 0 ° C., the power supply terminal 5 was brazed and fixed to manufacture the wafer support member 1.

Therefore, an AC voltage is applied between the power supply terminals 5 of the wafer support member 1 so that the maximum temperature of the mounting surface 3 becomes 850.
° C, and after maintaining at this temperature for 10 minutes, a heat cycle test of rapidly cooling to room temperature with a cooler is repeated, and whether or not there is abnormal heat generation, whether or not the internal electrode 4 is disconnected, and whether or not the plate-shaped ceramic body 2 An experiment was conducted to check for damage. It should be noted that the abnormal heat generation was judged to be abnormal heat when the temperature fluctuation became ± 5% or more because the temperature fluctuation of the mounting surface 3 increased when the abnormal heat generation occurred.

As a result, no breakage of the plate-shaped ceramic body 2 was observed even in the heat cycle test 200 times, and no disconnection of the internal electrode 4 was found. Moreover, a stable temperature distribution in which the temperature variation of the mounting surface 3 is always ± 2% or less is obtained,
There was no abnormal fever.

(Experimental Example 1) Here, in the wafer support member 1 in the embodiment, a heat cycle test similar to that in the embodiment was performed by changing the material of the stress relaxation material 8, and the presence or absence of abnormal heat generation and the disconnection of the internal electrode 4 were performed. An experiment was conducted to check for the presence or absence of. In addition,
Except for changing the material of the stress relaxation material 8, the other conditions were the same as those in the example. Further, a wafer support member 21 having the structure shown in FIG.
This was also tested.

The results are as shown in Table 1.

[0044]

[Table 1]

As a result, as shown in FIG.
In the structure shown in FIG. 7, no disconnection of the internal electrode 4 was observed after about 50 times. However, abnormal heat generation was observed in 10 out of 20 wafers, and the internal electrodes 4 were disconnected in all the wafer support members 21 before performing the thermal cycle test 200 times.

In the structure shown in FIG. 4 in which beryllia is used as a stress relaxation material, the plate-like ceramic body 2
Is larger than + 2.9 × 10 ^-6 / ° C.
In 50 heat cycle tests, abnormal heat generation was observed in 8 out of 20 wafers, and in 200 heat cycle tests, abnormal heat generation was observed in all wafer support members 21.

On the other hand, alumina as a stress relaxing material
In any of those using cemented carbide, silicon nitride, and spodumene, the difference in thermal expansion from the plate-like ceramic body 2 is + 2.9 × 10
^-6 / ° C. or less, there is no disconnection of the internal electrode 4 even in the thermal cycle test 200 times, and the temperature variation of the mounting surface 3 as in the case of using aluminum nitride as the stress relaxation material. However, a stable temperature distribution of always ± 2% or less was obtained, and no abnormal heat generation was observed.

(Experimental Example 2) Next, in the wafer support member 1 in the embodiment, the distance from the entrance of the pilot hole 2a of the plate-shaped ceramic body 2 to the tip end surface of the stress relaxation material 8 was changed, similarly to the embodiment. The heat cycle test was performed, and an experiment was conducted to determine whether there was abnormal heat generation and whether the plate-shaped ceramic body 2 was damaged. Except for changing the depth of the concave portion 5a formed in the power supply terminal 5 and the length of the distal end portion 8a of the stress relaxation material 8, the other conditions were the same as those in the example.

The results are as shown in Table 2.

[0050]

[Table 2]

As a result, when the distance L was in the range of 0 to 5 mm, no abnormal heat generation was observed even in the heat cycle test 200 times. However, when the distance L is larger than 4 mm,
Cracks were observed in the plate-shaped ceramic body 2 in 50 heat cycle tests, and cracks occurred in the plate-shaped ceramic body 2 in half or more of the 10 heat cycle tests in 200 heat cycle tests.

On the other hand, when the distance L is in the range of 0 to 3 mm, the plate-like ceramic body 2 is not subjected to 200 heat cycle tests.
Had no cracks and could be used for a long time.

From this result, the distance L from the entrance of the pilot hole 2a of the plate-shaped ceramic body 2 to the tip end surface of the stress relaxation material 8 is 3
It can be seen that it is better to set the thickness to not more than mm.

[0054]

As described above, according to the present invention, the upper surface of the plate-shaped ceramic body in which the internal electrodes are buried is used as the wafer mounting surface, and the internal electrodes are penetrated through the lower surface of the plate-shaped ceramic body. In the wafer support member having a lower hole to which the power supply terminal is brazed and fixed, a concave portion is provided on an end surface on the joining side of the power supply terminal, and a thermal expansion difference between the concave portion and the plate-shaped ceramic body is provided in the concave portion. Is not more than + 2.9 × 10 ⁻⁶ / ° C. and a stress relaxation material having a protruding portion partially protruding from the end face on the joining side of the power supply terminal is inserted. 550 is fixed by brazing the pilot hole to the exposed portion of the internal electrode in the pilot hole and the exposed portion of the internal electrode in the pilot hole.
Even if repeatedly heated to a high temperature of ℃ or more, there is no breakage of the plate-shaped ceramic body due to thermal stress, and there is no abnormal heating and internal electrode disconnection due to peeling of the brazing material, so it can be used for a long time in a high temperature range A highly durable wafer support member can be provided.

Moreover, the plate-shaped ceramic body constituting the wafer support member has excellent corrosion resistance to halogen-based gas such as fluorine-based or chlorine-based, so that a film-forming apparatus or an etching apparatus in a semiconductor device manufacturing process. Can also be suitably used. Further, the present invention, since the distance from the entrance of the prepared hole perforated in the plate-shaped ceramic body to the front end surface of the stress relaxation material is 3 mm or less, to reduce the thermal stress acting near the entrance of the prepared hole, Damage of the pilot hole entrance can be prevented.

Further, according to the present invention, the stress relaxation material is formed of insulating ceramics, and a conductor layer is buried inside the stress relaxation material so that a part of the conductor layer is exposed from the side surface of the protrusion. The internal electrode is a plasma generating electrode, and even if a large current is applied, abnormal heat generation is not generated near the internal electrode exposed in the prepared hole of the plate-shaped ceramic body, and the temperature distribution on the mounting surface is made uniform. be able to.

In the present invention, the power supply terminal is made of Au-Ni.
Since the system brazing material is coated, the oxidation resistance of the power supply terminal can be increased and the durability can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example in which a wafer supporting member of the present invention is used as a susceptor with a built-in heater, and FIG.
(B) is XX sectional drawing.

FIGS. 2A and 2B are diagrams showing an example in which the wafer support member of the present invention is used as an electrostatic chuck with a built-in heater, wherein FIG. 2A is a perspective view thereof, and FIG.

FIG. 3 is a perspective view showing a power supply terminal and a stress relaxation material used for a wafer support member of the present invention.

FIG. 4 is an enlarged cross-sectional view of a joint between a prepared hole of a plate-shaped ceramic body and a power supply terminal.

FIG. 5 is an enlarged cross-sectional view of a junction of a power supply terminal when a plasma generating electrode is embedded as an internal electrode.

FIG. 6 is a perspective view showing a stress relaxation material used for a joint portion of the power supply terminal shown in FIG.

7A and 7B are diagrams showing an example in which a conventional wafer supporting member is used as a susceptor with a built-in heater, and FIG.
(B) is a sectional view taken along line AA.

8A and 8B are views showing an example in which a conventional wafer support member is used as an electrostatic chuck with a built-in heater, and FIG.
(B) is a sectional view taken along line BB.

FIG. 9 is a cross-sectional view showing a joint portion between a prepared hole of a plate-shaped ceramic body and a power supply terminal previously proposed by the present applicant.

[Explanation of symbols]

1,11,21,31 ...
Wafer support members 2, 12, 22, 32 ...
Plate-shaped ceramic bodies 2a, 12a, 12b, 22a, 32a, 32b,...
Prepared holes 3,13,23,33 ・ ・ ・
Mounting surface 4,14,16,24,34,36 ...
Internal electrode 5, 15, 17, 25, 35, 37 ...
Power supply terminals 5a, 15a, 17a, 25a, 35a, 37a ...
Recesses 5b, 15b, 17b, 25b, 35b, 37b ...
Thin section 8, 18, 19 ...
Stress relief material 8a, 18a, 19a ...
Tip portions 8b, 18b, 19b ...
Projection W
Semiconductor wafer

Claims (4)

[Claims] An upper surface of a plate-like ceramic body in which internal electrodes are embedded is used as a wafer mounting surface, and a lower hole penetrating the internal electrode is provided on a lower surface of the plate-like ceramic body, and power is supplied to the lower hole. In the wafer support member having the terminals fixed by brazing, a concave portion is provided on an end surface on the joining side of the power supply terminal, and the thermal expansion difference between the concave portion and the plate-shaped ceramic body is + 2.9 × 10.
^-6 / ° C. or less and a stress relaxation material having a protrusion partly protruding from the end face on the joining side of the power supply terminal is inserted,
A wafer support member, wherein the power supply terminal is brazed and fixed to a lower hole of the plate-shaped ceramic body, and a protruding portion of the stress relaxation material is brazed and fixed to an exposed portion of an internal electrode in the lower hole. 2. The wafer supporting member according to claim 1, wherein a distance from an entrance of a pilot hole formed in the plate-shaped ceramic body to a front end surface of the stress relaxation material is 3 mm or less. 3. The semiconductor device according to claim 1, wherein said stress relaxation material is formed of insulating ceramics, and a conductor layer is buried therein, and a part of said conductor layer is exposed from a side surface of said projection. And the wafer support member according to claim 2. 4. The wafer supporting member according to claim 1, wherein the power supply terminal is coated with an Au—Ni-based brazing material.