JPH11111827A - Holding device and processing apparatus equipped with the holding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uncrack even at a high temperature and unremove an electrostatic chuck from a metallic heater due to a thermal distortion, by a method wherein a thermal expansion buffer layer having an intermediate thermal expansion coefficient between thermal expansion coefficients of the electrostatic chuck, and a heater is provided between the electrostatic chuck and the heater and jointed thereto. SOLUTION: A holding device comprises a metallic heater 3 in which a heating body 5 is buried, an electrostatic chuck 11 made of ceramics, and a thermal expansion buffer layer 6 joined and provided between the heater 3 and the electrostatic chuck 11. The thermal expansion buffer layer 6 has a thermal expansion coefficient between that of the electrostatic chuck 11 and that of the heater 3. Thus, a difference in the thermal expansion coefficients between the electrostatic chuck 11 and the heater 3 is scattered as a small difference in the thermal expansion coefficients between the electrostatic chuck 11 and the thermal expansion buffer layer 6 and a small difference in the thermal expansion coefficients between the heater 3 and the thermal expansion buffer layer 6, and a stress distortion due to a difference in the thermal expansion coefficients applied on the electrostatic chuck 11 is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a holding device and a processing apparatus provided with the holding device.

[0002]

2. Description of the Related Art An etching apparatus which is a semiconductor manufacturing apparatus,
In a holding device provided with an electrostatic chuck and a heater used in a CVD device, a sputtering device, and the like, the electrostatic chuck and the heater are formed as a single body. That is, a comb-shaped electrode for electrostatic chucking and a spiral heating element for heating are buried in a ceramic material, and this integrated body serves as both an electrostatic chuck and a heater. In this case, the ceramic material may be alumina (Al ₂ O ₃ ) from the viewpoint of corrosion resistance. However, this integrated material must be thick because the electrode and the heating element are embedded. I can't get it. However, alumina has a low thermal conductivity, a high thermal gradient, and a low thermal shock resistance. There was a defect.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a holding device having an electrostatic chuck and a heater which does not easily crack even at a high temperature and does not come off from a metal heater due to thermal distortion. It is an object of the present invention to provide an apparatus and a processing apparatus provided with the holding apparatus.

[0004]

According to a first aspect of the present invention, there is provided a holding device comprising: a plate-shaped metal heater having a heating element embedded therein; and a ceramic plate-shaped heater. And a thermal expansion buffer layer provided between and joined to the heater and the electrostatic chuck, wherein the thermal expansion buffer layer has a coefficient of thermal expansion of the electrostatic chuck. It has a coefficient of thermal expansion between the coefficient of thermal expansion of the heater.

According to a second aspect of the present invention, in the first aspect of the present invention, the thermal expansion buffer having a thermal expansion coefficient substantially equal to that of the thermal expansion buffer layer on the surface of the heater opposite to the electrostatic chuck. It is characterized in that the layers are joined.

[0006] The invention described in claim 3 is the invention according to claim 1 or 2.
In the invention described in (1), a protective layer that covers the outer surface of the thermal expansion buffer layer together with the electrostatic chuck is provided.

[0007] The invention described in claim 4 is the invention according to claims 1 to 3.
In the invention described in any one of the above, the thermal expansion buffer layer is made of a ceramic-metal composite.

According to a fifth aspect of the present invention, in the fourth aspect, the ceramic-metal composite is formed of a silicon carbide-aluminum composite, an aluminum nitride-aluminum composite, or an alumina-aluminum composite. It is characterized by.

The invention according to claim 6 is the invention according to claims 1 to 3
In the invention described in any one of the above, the thermal expansion buffer layer is made of titanium.

[0010] The invention described in claim 7 is the invention according to claim 5 or 6.
In the invention described in (1), the material of the electrostatic chuck is alumina, aluminum nitride, or boron nitride, and the material of the heater is aluminum.

An eighth aspect of the present invention is directed to a processing apparatus comprising the holding device according to any one of the first to seventh aspects.

[0012]

Embodiments of the present invention (hereinafter, referred to as "embodiments") will be described in detail with reference to the drawings. FIG. 1 shows one embodiment of the holding device of the present invention, and FIG.
FIG. 3 shows the volume ratio of silicon carbide to aluminum of the silicon carbide-aluminum composite, which is one of the materials suitable for the thermal expansion buffer layer of this holding device, versus the coefficient of linear expansion, and FIGS.
Are embodiments of an etching apparatus, a CVD apparatus, and a sputtering apparatus belonging to a semiconductor manufacturing apparatus using the holding apparatus of this embodiment.

As shown in a longitudinal sectional view in FIG.
Has a disk-shaped heater 3 having a cylindrical flange portion 2 formed at the center of one surface (the lower surface in FIG. 1). This heater 3
It is formed by casting aluminum while embedding a spiral linear heating element 5 (for example, Kanthal wire) covered with an outer coating 4 of an insulator such as boron nitride BN. However,
The heater 3 is not limited to aluminum, but may be a metal having high heat resistance and high thermal conductivity, for example, stainless steel SUSC3.

On both end surfaces 8 and 9 of the heater 3, disk-shaped thermal expansion buffer layers 6 and 7 having the same diameter as the heater 3 and substantially the same thickness as each other.
To join. The materials and uses of these thermal expansion buffer layers 6 and 7 will be described later.

One end face (the lower end face in FIG. 1) of a disk-shaped electrostatic chuck 11 coaxially with the heater 3 or the thermal expansion buffer layer 6 is formed on the outer surface 10 of one of the thermal expansion buffer layers 6 (the upper one in FIG. 1). ) To join. Since the electrostatic chuck 11 has only embedded comb-shaped electrodes 12 and 13 and does not include a heater unlike the conventional chuck, for example, the thickness of the integrated electrostatic chuck and the heater is 1 mm. / 10.

It is desirable that the material of the electrostatic chuck 11 has a high thermal shock resistance and does not crack even when distortion is caused by high heat. However, alumina (Al ₂ O ₃ ) has the advantage of not chemically reacting with the treatment medium or the active substance, but has a low thermal shock resistance and is likely to be damaged by heat when the wall thickness is large. However, even with alumina, if the wall thickness is reduced as in this case, cracks will not occur even if the temperature becomes high. Therefore, alumina (Al ₂ O ₃ ) having poor thermal shock resistance can be used for the electrostatic chuck 11 of the present invention. However, the material of the electrostatic chuck 11 may be another ceramic such as aluminum nitride (AlN), for example.

As described above, since the electrostatic chuck 11 is made of ceramic and the heater 3 is made of metal, the difference between the two is very large. For example, the electrostatic chuck 1
1 is made of alumina, the linear thermal expansion coefficient of alumina is 7.8 to 8.1 × 10 ⁻⁶ , and when the heater 3 is made of aluminum, the linear thermal expansion coefficient of aluminum is 22 to 2
At 4 x 10 ^-6 , there is a great difference between the two. for that reason,
If the two are directly joined at a high temperature, after cooling, the electrostatic chuck 11 and the heater 3 are warped due to the difference in thermal expansion coefficient, and the electrostatic chuck 11 is distorted. As a result,
There is a problem that the electrostatic chuck 11 is cracked or peels off from the heater 3.

On the other hand, the thermal expansion buffer layer 6 having a thermal expansion coefficient intermediate between the thermal expansion coefficients of the electrostatic chuck 11 and the heater 3 and made of a ceramic-metal composite having high thermal shock resistance. Is provided between the electrostatic chuck 11 and the heater 3 and bonded to each other, the difference in the coefficient of thermal expansion between the electrostatic chuck 11 and the heater 3 causes the thermal expansion coefficient between the electrostatic chuck 11 and the thermal expansion buffer layer 6 to increase. Dispersed into a small difference in expansion coefficient and a small difference between thermal expansion coefficients between the heater 3 and the thermal expansion buffer layer 6, stress or distortion due to the difference in thermal expansion coefficient applied to the electrostatic chuck 11 is reduced, and static electricity is reduced. Damage to the electric chuck 11 and detachment from the heater 3 can be prevented. The thickness of the thermal expansion buffer layer 6 is set to, for example, the same thickness as that of the heater 3 in order to reduce distortion applied to the thermal expansion buffer layer 6 due to a difference in thermal expansion coefficient between the electrostatic chuck 11 and the heater 3. I do. On the other hand,
A thermal expansion buffer layer 7 of the same material and the same size as the thermal expansion buffer layer 6 is also joined to the end face of the heater 3 on the side opposite to the thermal expansion buffer layer 6. This is to prevent the heater 3 from being bent when the heater 6 is joined.

A portion of the outer end surface of the upper thermal expansion buffer layer 6 to which the electrostatic chuck 11 is joined, to which the electrostatic chuck 11 is not joined, an outer end surface of the lower thermal expansion buffer layer 7, Aluminum is cast on the buffer layers 6 and 7 and the outer peripheral surface of the heater 3 to form a protective layer 14. The protective layer 14 and the electrostatic chuck 11 completely cover the outer surfaces of the thermal expansion buffer layers 6 and 7. . Therefore, when the holding device 1 is installed in a processing chamber of a processing apparatus such as a semiconductor manufacturing apparatus and the above-described processing medium (processing gas) is introduced into the processing chamber, the thermal expansion buffer layers 6 and 7 perform this processing. It does not come into contact with the above-mentioned activators such as media or activated fluorine. Therefore, the material of the thermal expansion buffer layers 6 and 7 may be a material that causes a chemical reaction with the above-described processing medium or activator as long as the thermal expansion coefficient has an intermediate value described above. In addition, the protective layer 14 does not cause a chemical reaction with the above-described active substance such as a processing medium or activated fluorine, and as long as the mechanical strength is high, for example, a metal such as stainless steel SUS3 or a ceramic material. Such other materials may be used.

A power supply pipe 15 is provided at the center of the end face (lower end face in FIG. 1) of the protective layer 14 opposite to the electrostatic chuck 11. The central portion of the thermal expansion buffer layer 6, the central portion of the heater 3, and the cylindrical flange portion 2 are connected to another feed pipe 1.
6 penetrates. A lead 17 extends from the electrodes 12 and 13 through the feed pipes 15 and 16,
, A lead wire 18 extends through the feed pipe 15. These lead wires 17 and 18 are respectively connected to a predetermined power supply (not shown).

The material of the thermal expansion buffer layers 6 and 7 is, for example, a composition having a thermal expansion coefficient intermediate between the linear thermal expansion coefficients of aluminum and alumina from a silicon carbide-aluminum composite (SiC-Al composite). It is desirable to choose one. FIG. 2 shows the silicon carbide-aluminum composite (Si
2 shows the volume ratio of silicon carbide to aluminum (C-Al composite) versus linear expansion coefficient characteristics. In the silicon carbide-aluminum composite, the volume ratio of silicon carbide to aluminum is 50:50.
If the ratio is less than 75, the breakage rate becomes high, and the volume ratio becomes 75:25.
If the ratio exceeds 50, the production cost increases rapidly. Therefore, as the above-mentioned intermediate thermal expansion coefficient, a silicon carbide to aluminum volume ratio in the range of 50:50 to 75:25 can be considered.

On the other hand, when the volume ratio becomes 50:50 or more, the difference in the thermal expansion coefficient between the electrostatic chuck 11 and the thermal expansion buffer layer 6 becomes larger than the thermal expansion coefficient between the heater 3 and the thermal expansion buffer layer 6. Is less than half of the difference. Therefore, when the electrostatic chuck 11 is joined to the heater 3 by the thermal expansion buffer layer 6,
The stress or strain applied to the electrostatic chuck 11 is substantially less than half of the stress or strain when the electrostatic chuck 11 is directly joined to the heater 3. Therefore, if a silicon carbide-aluminum composite having a volume ratio of 50:50 or more is used as the material of the electrostatic chuck 11, it is effective to prevent the damage of the electrostatic chuck 11 or peeling from the heater 3.

As will be understood from the above description, considering the damage of the electrostatic chuck 11 and the prevention of peeling from the heater 3, the breakage rate of the silicon carbide-aluminum composite, and the manufacturing cost, the silicon carbide-aluminum composite The material having a silicon carbide to aluminum volume ratio in the range of 50:50 to 75:25 can be adopted as the material of the thermal expansion buffer layers 6 and 7 having an appropriate intermediate thermal expansion coefficient.

Suitable materials for the thermal expansion buffer layers 6 and 7 include, for example, aluminum nitride-aluminum (AlN-A) in addition to the silicon carbide-aluminum composite described above.
1) Composite or alumina-aluminum (Al ₂ O ₃₎
-Al) complex. The thermal expansion coefficients of aluminum nitride and alumina are 4.5 × 10 ⁻⁶ and 7.8 to 8.1 × 10 ⁻⁶ (carbon nitride is 4 × 10
^-6 ), but since these composites have a volume ratio to linear thermal expansion coefficient characteristic similar to the volume ratio to linear thermal expansion coefficient characteristic of the components of the silicon carbide-aluminum composite,
The range of use of the volume ratio of the components of both composites is selected to be substantially the same as the range of use of the volume ratio of the components of the silicon carbide-aluminum composite. Note that other ceramic-metal composites having the above-described intermediate thermal expansion coefficient can also be used.

Further, as a material suitable for the thermal expansion buffer layers 6 and 7, titanium (having a thermal expansion coefficient of 8.6 × 1) is used.
0 close to the thermal expansion coefficient of alumina ^-6) there is. Although other metals have a coefficient of thermal expansion in this range, titanium is most suitable because active fluorine has high resistance to plasma.

As described above, in the present embodiment, by forming the electrostatic chuck and the heater separately, the electrostatic chuck can be formed thin, so that ceramics having low thermal shock resistance can be used as a material for the electrostatic chuck. This has the effect. Also, since the electrostatic chuck is made of ceramics and the heater is made of metal, the difference in thermal expansion coefficient between the two is large, so the thermal expansion buffer layer between them has a thermal expansion coefficient intermediate between the two. And join them with the
There is also an effect that distortion generated in the electrostatic chuck due to a difference in thermal expansion coefficient at a high temperature can be reduced to prevent damage and peeling from the heater. Further, since the outer surface of the thermal expansion buffer layer is covered with a metal layer that does not cause a chemical reaction with the processing medium, the thermal expansion buffer layer can be used in a chemical reaction with the processing medium as long as the intermediate thermal expansion coefficient is obtained. There is an effect that a ceramic-metal composite causing a change can be used as the material. In addition, since the heater is made of metal having high heat resistance and heat conductivity, there is also an effect that heat can be efficiently transmitted.

As described above, the holding device having the thermal expansion buffer layer bonded to the upper and lower surfaces of the heater and having the protective layer covering the outer surface of the thermal expansion buffer layer together with the electrostatic chuck has been described. Also, those without the thermal expansion buffer layer and the protective layer on the surface opposite to the electrostatic chuck, or those without the protective layer also belong to the scope of the present invention.

Next, a processing apparatus using the holding apparatus of the present embodiment is changed to an etching apparatus belonging to a semiconductor manufacturing apparatus, a CV
The D apparatus and the sputtering apparatus will be sequentially described as embodiments.

FIG. 3 is a longitudinal sectional view of an example of an etching apparatus which is an embodiment of the processing apparatus of the present invention. The etching apparatus 100 has a processing container 101 made of aluminum or the like. In a processing chamber 102 in the processing container 101, there is provided an upper electrode 103, and a holding device 1 below which an electrostatic chuck 11 faces a processing space S below.
Further, the wafer W is placed on the electrostatic chuck 11 each time the processing is performed. Since the holding device 1 is the same as that described with reference to FIG. 1, other portions are denoted by the same reference numerals as those in FIG. 1, and description thereof is omitted. A chamber-shaped processing gas header 1 is provided in the upper electrode 103.
04 is formed, and the processing gas inlet 105 communicates with this. A plurality of gas holes 10 communicating the processing gas header 104 and the processing space S are provided on the lower surface of the upper electrode 103.
6 are formed. Further, a processing gas outlet 107 communicating with the processing chamber 102 is formed on a side wall of the processing container 101. The upper electrode 1 is connected to a predetermined power supply (not shown).
03 is a lead wire for connecting the lead wire. When the wafer W is placed on the electrostatic chuck 11, a voltage is applied from a predetermined power supply (not shown) via the lead wire 109, and the electrodes W cooperate with the electrodes 12 and 13 of the electrostatic chuck 11. When these electrodes act, the wafer W is held in the electrostatic chuck 1
It is chucked to 1.

Next, the operation of the etching apparatus 100 and the operation of the holding device 1 will be described. A predetermined etching gas is supplied from the processing gas inlet 105 into the processing gas header 104 in a shower shape.
06 to the processing space S. At the same time, while the wafer W to be etched is placed on the electrostatic chuck 11, the heater 3 is heated to a predetermined temperature by energizing the heating element 5 of the holding device 1 via the lead wire 18, A predetermined voltage is applied between the wafer W and the electrodes 12 and 13 of the holding device 1 via the leads 109 and 17 to chuck the wafer W with the electrostatic chuck 11, and the upper electrode 103 and the lower electrode are connected via the leads 108 and 17. A predetermined high-frequency current is applied to the electrodes 12 and 13 of the electrostatic chuck 11 to be constituted.
When the pressure in the processing space S is maintained at a predetermined low pressure in this state, plasma is generated in the processing space S, and the surface of the wafer W is etched by the etching gas. After the end of the etching, the restrained state of the wafer W is released, and the used etching gas is discharged from the processing gas outlet 107. Finally, one cycle of the etching process is completed by removing the wafer W from the electrostatic chuck.

Since the structure of the CVD apparatus according to another embodiment of the present invention is basically the same as that of the etching apparatus, the mechanism shown in FIG. 3 can be used as it is. 100 is an example of the CVD apparatus of the present invention. This CVD apparatus 100 is an etching apparatus 10
The difference from 0 is that the processing gas is a processing gas for CVD, whereby the surface of the wafer W is subjected to CVD processing. Other structures and operations are performed by the etching apparatus 100.
Therefore, their description is omitted.

FIG. 4 shows still another embodiment of the processing apparatus of the present invention.
It is a longitudinal section of an example of the sputtering device which is an embodiment. The sputtering apparatus 200 has a processing container 201 made of aluminum or the like. A target 203 made of aluminum or the like, a magnet 204 provided thereabove, a target 2
The holding device 1 is provided below the substrate holder 03 with the electrostatic chuck 11 facing the processing space S therebetween. The wafer W is placed on the electrostatic chuck 11 each time the processing is performed. A processing gas inlet 205 and a processing gas outlet 206 are formed on the side surface of the processing container 201 so as to face each other. 207 is a lead wire for connecting the wafer W to a predetermined power supply (not shown).
Like the lead wire 108 in the etching apparatus 100 described above, the wafer W is used to provide a function as an electrode to the wafer W and to chuck the wafer W to the electrostatic chuck 11.

Next, the operation of the sputtering device 200 will be described together with the operation of the holding device 1. For example, a predetermined inert gas (processing gas) such as argon (Ar) is supplied from the processing gas inlet 205 to the processing space S. With this,
With the wafer W to be sputtered placed on the electrostatic chuck 11, the heater 3 is heated to a predetermined temperature by supplying electricity to the heating element 5 of the holding device 1 through the lead wire 18, and the lead wire 207 is heated. And 17, a predetermined voltage is applied to the wafer W and the electrodes 12 and 13 of the holding device 1 to chuck the wafer W with the electrostatic chuck 11 and to a predetermined low pressure in the processing space S (processing container 201). While maintaining, the magnet 204 is excited. In this way, the inert gas (processing medium) is turned into plasma in the processing space S. As a result, particles of a substance such as aluminum constituting the target 203 are beaten from the target 203 and sputtered on the wafer W.
After the completion of the sputtering process, the restrained state of the wafer W is released, and finally, the wafer W is removed from the electrostatic chuck 11 to complete one cycle of the sputtering process.

[0034]

According to the present invention, it is possible to provide a holding device which is unlikely to be cracked even at a high temperature and which is not detached from a metal heater due to thermal distortion due to thermal distortion, and a processing apparatus provided with this holding device. .

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of one embodiment of a holding device of the present invention.

2 is a graph showing a characteristic of a volume ratio of carbon nitride and aluminum to a coefficient of linear thermal expansion of a carbon nitride-aluminum composite which is a kind of a material of a thermal expansion buffer film used in the holding device of FIG. .

3 shows an etching device provided with the holding device of FIG. 1 and C
It is a longitudinal section schematic diagram of an embodiment of a VD device.

FIG. 4 is a schematic longitudinal sectional view of a sputtering apparatus provided with the holding device of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Holding device 3 Heater 5 Heating body 6, 7 Thermal expansion buffer layer 11 Electrostatic chuck 12, 13 Electrode 14 Protective layer 100 Etching apparatus, CVD apparatus 101 Processing container 102 Processing chamber 103 Upper electrode 104 Processing gas header 105 Processing gas inlet 107 Processing Gas outlet 200 Sputtering apparatus 201 Processing vessel 202 Processing chamber 203 Target 204 Magnet 205 Processing gas inlet 206 Processing gas outlet S Processing space W Wafer

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/3065 H01L 21/302 B (72) Inventor Shosa Endo 650 Mitsuzawa, Hosakacho, Nirasaki, Yamanashi Pref. Tokyo Electron Yamanashi Co., Ltd. (72) Inventor Nobuyuki Suzuki 26 at Ametaka, Numazu City, Shizuoka Prefecture

Claims (8)

[Claims] 1. A plate-shaped metal heater in which a heating element is buried, a ceramic plate-shaped electrostatic chuck, and a heater provided between the heater and the electrostatic chuck. A holding device, comprising: a thermal expansion buffer layer, wherein the thermal expansion buffer layer has a thermal expansion coefficient between a thermal expansion coefficient of the electrostatic chuck and a thermal expansion coefficient of the heater. 2. The heater according to claim 1, wherein a thermal expansion buffer layer having a coefficient of thermal expansion substantially equal to that of the thermal expansion buffer layer is bonded to a surface of the heater opposite to the electrostatic chuck. A holding device as described. 3. The holding device according to claim 1, further comprising a protective layer that covers an outer surface of the thermal expansion buffer layer together with the electrostatic chuck. 4. The holding device according to claim 1, wherein the thermal expansion buffer layer is made of a ceramic-metal composite. 5. The holding device according to claim 4, wherein the ceramic-metal composite is a silicon carbide-aluminum composite, an aluminum nitride-aluminum composite, or an alumina-aluminum composite. 6. The holding device according to claim 1, wherein the thermal expansion buffer layer is made of titanium. 7. The holding device according to claim 5, wherein the material of the electrostatic chuck is alumina, aluminum nitride, or boron nitride, and the material of the heater is aluminum. 8. A processing apparatus comprising the holding device according to claim 1.