JPH1080168A - Electrostatic chuck - Google Patents

Abstract

(57) Abstract: An electrostatic chuck electrode pattern is bonded to a surface of a support substrate made of electrically insulating ceramics, and a pattern having the same or similar shape as the electrostatic chuck electrode pattern is formed on the back surface. An electrostatic chuck characterized by being joined. According to the present invention, in an electrostatic chuck for attracting a wafer or the like serving as a substrate of a semiconductor device by using static electricity, and further, in an electrostatic chuck with a heater having a heating function, an electrostatic chuck is provided on the surface of the supporting substrate. A chuck pattern is formed, and a pattern or a heat generation pattern having the same or similar shape as the pattern is formed on the back surface, so that even when the substrate is thin and compact, the occurrence of warpage during its manufacture is suppressed,
In addition, when the wafer is heated or cooled, the electrostatic chuck and the electrostatic chuck with a heater have the advantage that the electrostatic chucking force is stabilized without causing thermal deformation and warpage, and the performance is excellent at low cost. And an electrostatic chuck with a heater.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic chuck for attracting a wafer or the like serving as a substrate of a semiconductor device using static electricity and an electrostatic chuck with a heater having a heating function.

[0002]

2. Description of the Related Art In a recent semiconductor device manufacturing process, an electrostatic chuck is used for electrostatically holding a wafer by molecular beam epitaxy, CVD, sputtering, etching or the like. The material of this electrostatic chuck has been changed from resin to ceramic with the increase in the temperature of the process (Japanese Patent Laid-Open No.
2-67353, JP-A-59-124140). Recently, a ceramic heater with an electrostatic chuck in which a ceramic heater and an electrostatic chuck are combined has been proposed (JP-A-5-109876,
See JP-A-5-129210).

In this case, molecular beam epitaxy, CVD,
When forming a film in sputtering or the like, the temperature of the wafer has a great influence on the properties of the film and the film forming speed. Further, in dry etching, since the temperature of the wafer has a great influence on the etching shape, selectivity, distribution, and the like in fine etching, improvement in cooling performance for cooling the wafer is required.

In manufacturing this electrostatic chuck, an electrode pattern for the electrostatic chuck is joined to a substrate, and an insulating layer is further provided. The material of the substrate and the insulating layer differs from that of the pattern layer.
In particular, due to the different coefficients of thermal expansion, warpage occurs in the thermal history at the time of manufacture, and when the warpage is large, some pattern layers appear on the surface when polishing and finishing the surface of the insulating layer, or to not appear Also, the insulation withstand voltage of the insulating layer is reduced, resulting in a defective product. Further, even if the polishing is successfully completed, thermal deformation or warpage of the electrostatic chuck occurs due to the difference in the coefficient of thermal expansion when heating and cooling the wafer, and as a result, the chuck is attracted during heating or cooling of the electrostatic chuck. There was concern that power would not be stable. To solve this problem, the substrate may be made thicker, but the heat capacity is increased, so that the power consumption is increased. Further, it takes time to raise and lower the temperature, and the cost is increased. A compact one was desired. However, if the thickness is reduced, the above-described problem occurs, so that the substrate has to be thickened.

SUMMARY OF THE INVENTION The present invention has been made to improve the above circumstances, and provides an electrostatic chuck capable of obtaining a stable electrostatic attraction force from a low temperature to a high temperature with a small warpage at the time of manufacturing even if the substrate is thin and compact. An object of the present invention is to provide an electrostatic chuck with a heater.

[0006]

Means for Solving the Problems and Embodiments of the Invention As a result of diligent studies to achieve the above object, the present inventor has formed an electrostatic chuck pattern on the surface of the supporting substrate and formed the electrostatic chuck pattern on the back surface. By forming a pattern having the same or similar shape as the electro-chuck pattern, in this case, preferably by forming both patterns to have substantially the same thickness,
The thermal deformation due to the difference in thermal expansion coefficient between the substrate and the pattern cancels out on the front and back, even if the substrate is thin and compact, the occurrence of warpage during its manufacture is suppressed, and when the wafer is heated or cooled, the electrostatic chuck and The present inventor has found that the electrostatic chucking force of the heater-equipped electrostatic chuck is stable without causing thermal deformation and warpage, and the present invention has been accomplished.

That is, according to the present invention, (1) an electrode pattern for an electrostatic chuck is bonded to the surface of a support substrate made of electrically insulating ceramics, and the back surface has the same or similar shape as the electrode pattern for an electrostatic chuck. (2) The electrostatic chuck according to the above (1), wherein at least a part of the pattern on the back surface is a heat generating pattern configured as a heat generating portion by applying a current. An electrostatic chuck (electrostatic chuck with a heater); (3) the electrode pattern for the electrostatic chuck on the front surface and the pattern on the back surface are formed of a material having substantially the same thermal expansion coefficient as each other, more preferably substantially The electrostatic chuck according to the above (1) or (2), having the same thickness.

Hereinafter, the present invention will be described in more detail.
As shown in FIGS. 1 and 2, the electrostatic chuck of the present invention
An electrostatic chuck electrode pattern 2 having conductivity is formed on the surface of a support substrate 1 made of electrically insulating ceramics, and a pattern 3 is also formed on the back surface. In this case, the protective layer 4 is formed so as to cover the front and back patterns 2 and 3 respectively.

According to the present invention, in such a configuration, the patterns 2 and 3 on the front and back are formed in the same or similar shape as shown in FIGS.

Here, when the front and back patterns 2 and 3 are the same or similar, the front and back basic shapes (for example, concentric, radial, spiral, and comb shapes) match, and the gap between the front and back patterns, the pattern edge, and the like are 2 mm. Below, when the front and back patterns are overlapped, it is desirable that the area of the non-overlapping portion is 30% or less of that of the overlapping portion. From these points, the front and back patterns 2 and 3 in FIGS. 1B and 1C and the front and back patterns 2 and 3 in FIGS. 2B and 2C are similar to each other, but FIG. This is, of course, out of the scope of the present invention since no pattern is formed, and FIGS. 4 and 5 are out of the scope of the present invention because the front and back patterns 2 and 3 are not similar.

In this case, as shown in the figure, the pattern 2 on the front side can be formed in accordance with a well-known pattern system so as to be provided with an electrostatic chuck function by being connected to a power supply and applying a voltage. it can. Here, what is shown is a pattern that is said to be bipolar,
The same applies to the monopolar type.

On the other hand, as shown in FIG. 1, a plurality of patterns 3a are formed independently of each other, such as a plurality of ring-shaped patterns formed concentrically, as shown in FIG.
In particular, a pattern that does not consider the electrical connection with the mutual pattern 3a may be used. As shown in FIG.
By being connected to a power supply and applying a voltage, it can be formed as heat generating patterns 3b and 3c constituting a heat generating portion. In the case of the electrostatic chuck shown in FIG. It is formed.

It is preferable that the front and back patterns 2 and 3 have substantially the same thickness. In this case, these front and back patterns 2 and 3 are usually 10 to 500 μm.
m, especially 20 to 200 μm in thickness, but the fact that the front and back patterns 2 and 3 have substantially the same thickness means that the difference in thickness between the front and back patterns 2 and 3 is 100 μm or less. And it is particularly preferable that the thickness be 50 μm or less.

The thickness of the substrate 1 is appropriately selected.
Usually, it can be formed to a thickness of 2 to 50 mm, particularly 10 to 30 mm. However, in the present invention, the substrate 1 can be formed to a thickness of 5 mm or less because there is no problem such as warpage even if the substrate 1 is thin.

The thickness of the front and back protective layers 4 is preferably 10 to 2000 μm, and more preferably 50 to 1000 μm.
5 are preferably formed to have substantially the same thickness as each other, that is, so that the difference in thickness of the protective layer 4 is 300 μm or less, particularly 100 μm or less.

The material of the substrate 1 can be appropriately selected from electrically insulating ceramics, and can be formed of the same material as the substrate of the conventional electrostatic chuck.
It is preferably formed of BN, a composite of AlN and BN, PBN or SiO ₂ . In this case, the front and back protective layers 4 are also made of AlN, BN, a composite of AlN and BN, PBN.
Or it is preferable to form at SiO _2, in particular that the same thermal expansion coefficient, it is preferable that the front and back protective layer 4 is formed by mutually the same material, even a protective layer 4 of the front and back substrates 1 is preferably the same material.

On the other hand, the electrode pattern 2 for electrostatic chuck formed on the surface of the substrate 1 is formed of a conductive material. As the material, a known pattern forming material can be used. And the like, and a conductive ceramic such as carbon, and a metal mainly composed of W, Pt, Ag, Cu and the like.

The pattern 3 formed on the back surface of the substrate 1 can be preferably formed of a material having substantially the same coefficient of thermal expansion as the pattern 2 on the front surface. Of the conductive ceramic, carbon, or metal, and is particularly preferably formed of the same material as the surface pattern. In addition, it is preferable that the difference between the thermal expansion coefficients of the front and back patterns 2 and 3 is 1 × 10 ⁻⁵ / ° C. or less, particularly 3 × 10 ⁻⁶ / ° C. or less.

As described above, the electrostatic chuck pattern is formed on the surface of the supporting substrate, and the pattern having the same or similar shape as the surface pattern is formed on the back surface. In the case where a protective layer is formed, the insulating layer is made of the same material as the supporting substrate or has the same characteristics as that of the supporting substrate. Heating or cooling can be improved in heating performance or cooling performance, and stability during heating or cooling can be improved.

The method of forming the support substrate, the pattern, and the protective layer is not particularly limited, and various known methods can be adopted. The support substrate is formed by a chemical vapor deposition method or a pulverized sintering method. The pattern and the protective layer are preferably formed by a CVD method, a PVD method, a vacuum evaporation method, or the like. In this case, these methods can be performed according to a conventional method.

[0021]

EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Example 1, Comparative Example 1 A support substrate made of pyrolytic boron nitride having an outer diameter of 100 mm and a thickness of 2, 5, or 10 mm was prepared by reacting ammonia and boron trichloride at 1800 ° C. under 100 Torr. And then methane gas 220
Pyrolyze at 0 ° C and 5 Torr and add
A pyrolytic graphite layer having a thickness of 0 μm was formed, and a pattern as shown in FIGS. 1 to 5 was formed on the front and back surfaces using an end mill. Further, ammonia and boron trichloride were added at 100 Torr.
A thermal decomposition boron nitride insulating layer having a thickness of 200 μm was provided below by reacting at 1800 ° C., and 15 types of electrostatic chucks having different substrate thicknesses and pattern shapes and electrostatic chucks with heaters were manufactured.

FIG. 6 shows the relationship between the substrate thickness of each pattern type and the warpage after manufacturing. The electrostatic chuck pattern on the surface of the supporting substrate is formed concentrically, and the concentric pattern or the heating pattern having the same shape as the pattern on the back surface (FIGS. 1 and 2) is warped even when the substrate thickness is as thin as 2 mm. It has been confirmed that a good electrostatic chuck and a heater-equipped electrostatic chuck with less heat can be produced.

Embodiment 2 and Comparative Example 2 The surfaces of the substrates manufactured in Example 1 and Comparative Example 1 of FIGS. 1 and 2 with a substrate thickness of 2 mm and those of FIG. 4 with a substrate thickness of 10 mm were polished. The applied voltage was set to 500 V, and the temperature dependency of each electrostatic attraction force was measured.

As a result, the substrate thickness 1 from room temperature to 400 ° C.
At 0 mm, the pattern shown in FIG.
In the case of the pattern No. 2, the same adsorption power was obtained in all temperature ranges. From this, even if the board thickness is reduced, if the design is made in consideration of the similarity of the front and back of the pattern shape,
It was confirmed that stable electrostatic attraction force was obtained.

Example 3 and Comparative Example 3 A supporting substrate made of thermally decomposed boron nitride having an outer diameter of 100 mm and a thickness of 2 mm was prepared in the same manner as in Example 1 and Comparative Example 1, and then thermally decomposed to a thickness of 200 μm. A graphite layer was formed, an electrostatic chuck pattern was concentrically formed on the front surface, and a concentric heat generation pattern having the same diameter as the front surface pattern was processed on the back surface using an end mill.
After that, the conductive layer serving as the electrostatic chuck was sanded and polished to a thickness of 20 μm. Next, a pyrolytic boron nitride insulating layer is provided to produce an electrostatic chuck with a heater having different thicknesses of the front and back conductive layers, and the conductive layer serving as the electrostatic chuck is not polished. Warpage after manufacturing with the electrostatic chuck was compared.

As a result, the warpage was 50 μm when the thickness of the front and back conductive layers was the same, while the warpage was 300 μm when the conductive layer to be the electrostatic chuck was 20 μm. This deformation is different in the coefficient of thermal expansion between the conductive layer and the substrate,
It is considered that the thermal stress generated by the difference and the thickness of the conductive layer are involved, and therefore, it was recognized that it is preferable that the thickness of the front and back conductive layers be the same.

Example 4 and Comparative Example 4 A support substrate made of pyrolytic boron nitride having an outer diameter of 100 mm and a thickness of 2 mm was prepared in the same manner as in Example 1 and Comparative Example 1, and the surface was formed to a thickness of 10 mm.
A pyrolytic graphite layer having a thickness of 0 μm is formed, a Pt layer having a thickness of 100 μm is formed on the back surface by a vacuum deposition method, an electrostatic chuck pattern is formed concentrically on the front surface, and a concentric circle having the same diameter as the front surface pattern is formed on the back surface. The heat generation pattern was processed using an end mill. Next, a thickness of 200 μm is formed on the front and back conductive layers.
To form an electrostatic chuck with a heater in which the materials of the front and back conductive layers are different from each other.
Warpage after manufacturing was compared with an electrostatic chuck with a heater made of a pyrolytic graphite layer of 00 μm.

As a result, while the warpage of the latter is 50 μm, the former is larger than the latter and the warpage is 500 μm.
It has become. This is considered to be due to the difference in the coefficient of thermal expansion between the front and back conductive layer materials. Therefore, it was recognized that it is preferable that the front and back conductive layer materials be the same.

[0030]

According to the present invention, in an electrostatic chuck for attracting a wafer or the like serving as a substrate of a semiconductor device by using static electricity, and further, an electrostatic chuck with a heater having a heating function, An electrostatic chuck pattern is formed, and a pattern having the same or similar shape as the pattern or a heat generation pattern is formed on the back surface, so that even when the substrate is thin and compact, the occurrence of warpage during manufacturing is suppressed, and the wafer is heated. Alternatively, the electrostatic chuck and the heater-equipped electrostatic chuck have the advantage that the electrostatic chucking force is stabilized without generating thermal deformation and warpage when cooled, and the electrostatic chuck has excellent performance at low cost. And a heater-equipped electrostatic chuck.

[Brief description of the drawings]

FIGS. 1A and 1B show a first embodiment of the present invention, wherein FIG. 1A is a cross-sectional view taken along line AA of FIGS. 1B and 1C, FIG. 1B is a plan view, and FIG. It is.

FIGS. 2A and 2B show a second embodiment of the present invention, wherein FIG. 2A is a sectional view taken along line AA of FIGS. 2B and 2C, FIG. 2B is a plan view, and FIG. It is.

3A and 3B show a first comparative example of the present invention, wherein FIG. 3A is a cross-sectional view taken along line AA of FIGS. 3B and 3C, FIG. 3B is a plan view, and FIG. It is.

4A and 4B show a second comparative example of the present invention, wherein FIG. 4A is a cross-sectional view taken along line AA of FIGS. 4B and 4C, FIG. 4B is a plan view, and FIG. It is.

5A and 5B show a third comparative example of the present invention, wherein FIG. 5A is a cross-sectional view taken along line AA of FIGS. 5B and 5C, FIG. 5B is a plan view, and FIG. It is.

FIG. 6 is a graph showing a relationship between a substrate thickness and warpage in the electrostatic chucks of the examples and comparative examples of FIGS.

[Description of Signs] 1 substrate 2 electrode pattern for electrostatic chuck 3 pattern 4 protective layer

Claims (9)

[Claims] An electrode pattern for an electrostatic chuck is joined to a surface of a support substrate made of electrically insulating ceramics, and a pattern having the same or similar shape as the electrode pattern for an electrostatic chuck is joined to a back surface. An electrostatic chuck characterized by the above-mentioned. 2. The electrostatic chuck according to claim 1, wherein at least a part of the pattern on the back surface is a heat generating pattern configured as a heat generating portion by being connected to a power supply. 3. The electrostatic chuck according to claim 1, wherein the electrode pattern for the electrostatic chuck on the front surface and the pattern on the back surface are formed of materials having substantially the same thermal expansion coefficient as each other. 4. The electrostatic chuck according to claim 1, wherein the electrode pattern for the electrostatic chuck on the front surface and the pattern on the rear surface have substantially the same thickness. 5. The supporting substrate is made of AlN, BN, AlN and BN.
Complex, PBN or any one electrostatic chuck according to claims 1 to 4 is formed by SiO ₂ with. 6. The method according to claim 1, wherein the supporting substrate is formed by a chemical vapor deposition method or a powder sintering method, and the front and back patterns are respectively formed by a chemical vapor deposition method. Electrostatic chuck. 7. The electrostatic chuck according to claim 1, wherein a protective layer having substantially the same coefficient of thermal expansion as that of the support substrate is formed so as to cover the front and back patterns, respectively. 8. The protective layer is made of AlN, BN, a composite of AlN and BN, PBN or SiO ₂ .
An electrostatic chuck as described. 9. The electrostatic chuck according to claim 7, wherein the protective layer is formed by a chemical vapor deposition method.