JPH07326655A - Electrostatic chuck - Google Patents

Abstract

(57) [Abstract] [Purpose] The conductive and insulating layers that make up the electrostatic chuck do not peel off during operation in the semiconductor manufacturing process, there is no fear of contamination with impurities, etc. It is possible to obtain an electrostatic chuck that exhibits reliability and stability, and that does not require the use of an extremely high-purity raw material, and that has a low manufacturing cost. [Structure] Electrostatic chuck 1 for holding a silicon wafer, etc.
To cover at least the conductive layer 3, the base 2 made of an aluminum nitride sintered body, the conductive layer 3 mainly composed of molybdenum (Mo) and manganese (Mn) formed on the surface of the base 2. The heating layer 5 is formed by the insulating layer 4 formed of a film mainly composed of coated aluminum nitride, or by further incorporating the heating circuit 5 in the substrate 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic chuck used for electrostatically adsorbing and holding a silicon wafer in a semiconductor manufacturing apparatus or the like for processing or carrying, which is stable in a wide temperature range up to a high temperature. The present invention relates to an electrostatic chuck having excellent durability that can be used as a product.

[0002]

2. Description of the Related Art In semiconductor manufacturing equipment, in order to perform various kinds of fine processing such as patterning on a silicon wafer, a jig for fixing the wafer while maintaining its flatness is required. Mechanical type or vacuum adsorption type,
Various chucks such as an electrostatic chuck type have been proposed.

Among these chucks, the electrostatic chuck for electrostatically attracting and fixing the silicon wafer facilitates the flatness and parallelism of the processed surface required when performing various fine processing of the wafer. Since it can be realized and the wafer can be used even in a vacuum, it is most frequently used in the production of semiconductors.

In such a conventional electrostatic chuck, there is generally one in which an insulating layer made of alumina, sapphire or the like is formed on the surface of an electrode plate, and in addition, a conductive layer is formed on an insulating substrate, Those in which an insulating layer is formed thereon, those in which a conductive layer is incorporated inside an insulating substrate, and the like have been proposed.

In recent years, as the degree of integration of integrated circuits of semiconductor devices has improved, the precision required for electrostatic chucks has become more sophisticated, and therefore ceramics that are more excellent in corrosion resistance, wear resistance, and thermal shock resistance. Made electrostatic chucks have come into use.

However, in order to sinter ceramics such as silicon carbide, silicon nitride, aluminum nitride, etc., it is usually necessary to add a sintering aid to the raw material of the main component, and the ceramic product contains the sintering aid. It will inevitably exist.

On the other hand, the components of the semiconductor manufacturing apparatus must be made of a high-purity substance so that impurities are not mixed into the silicon wafer.

Therefore, when the ceramic product is used as an electrostatic chuck, the sintering aid contained in the mounting surface of the electrostatic chuck may contaminate the surface of the silicon wafer as an impurity. .

Therefore, in order to prevent contamination of a silicon wafer by impurities, an electrostatic chuck plate coated with a high-purity insulating layer having good adhesion has been proposed in Japanese Patent Laid-Open No. 4-34953.

[0010]

However, in the electrostatic chuck plate described above, although the adhesion between the base and the high-purity insulating layer is good, the conductive layer made of tungsten (W) or the like forms the base and the high-purity insulating layer. There is a problem in that the adhesiveness to both is insufficient and there is a risk of peeling, and there is concern about durability.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to prevent the conductive layer constituting the electrostatic chuck from peeling off during operation in the semiconductor manufacturing process, which may result in contamination by impurities or the like. In other words, the object is to provide an electrostatic chuck that exhibits excellent reliability and stability even at high temperatures for a long period of time and has a low manufacturing cost.

[0012]

In the electrostatic chuck of the present invention, molybdenum (Mo) and manganese (M) are formed on the surface of a substrate made of an aluminum nitride sintered body by a metallizing method.
a conductive layer containing n) as a main component is deposited, and at least the conductive layer is coated with a film mainly composed of aluminum nitride excellent in thermal shock resistance and fluorine plasma resistance by a vapor phase synthesis method, The coating layer has an oxygen content of 20 atomic% or less and has an insulating layer thickness of 0.001 to 1.0 mm, or has the same configuration as the above and has a heating circuit built in the substrate. It is characterized by.

[0013]

According to the electrostatic chuck of the present invention, since the alloy containing molybdenum (Mo) and manganese (Mn) as main components is deposited as the conductive layer, the manganese is applied to the substrate made of the aluminum nitride sintered body. The oxide layer of (Mn) diffuses and the adhesion to the substrate becomes strong.

Further, since the insulating layer composed of a film of aluminum nitride mainly having a high purity and excellent thermal conductivity is coated by the vapor phase synthesis method, the structure is homogeneous and the purity is very high and the plasma resistance is high. It is excellent and can prevent pinholes on the surface of the electrostatic chuck and deterioration due to etching. Even if a small amount of impurities are contained in the sintered body of the substrate, it is not released to the outside and the temperature inside the electrostatic chuck is high. The distribution is more uniform than in the case where the aluminum nitride sintered body is used alone, and the soaking property is improved.

On the other hand, since the heating circuit is built in the substrate, the electrostatic chuck can be downsized and the reliability is improved.

[0016]

The present invention will be described in detail below with reference to the drawings.
FIG. 1 is a sectional view showing a typical structure of the electrostatic chuck of the present invention. In FIG. 1, reference numeral 1 denotes a base 2 made of an aluminum nitride sintered body, a conductive layer 3 mainly composed of molybdenum (Mo) and manganese (Mn) deposited on the surface of the base 2, and at least a conductive layer 3. Is an electrostatic chuck composed of an insulating layer 4 made of a film mainly composed of aluminum nitride so as to cover the substrate and a heating circuit 5 built in the substrate 2.

The insulating layer 4 made of a film mainly composed of aluminum nitride is not limited to at least the mounting surface of the electrostatic chuck 1 on which the silicon wafer is placed, but the entire surface of the substrate 2 exposed in the semiconductor manufacturing apparatus. You may coat on.

In the present invention, the aluminum nitride sintered body of the substrate 2 is a Group 3a element oxide of the periodic table such as yttria (Y), erbium (Er), ytterbium (Yb) as a sintering aid, There is a case where an alkaline earth element compound such as calcium (Ca) is contained in a ratio of 20% by weight or less, but since these auxiliary components may act as impurities on the semiconductor in the semiconductor manufacturing device, It is preferable that the amount is small, and for example, a high-purity ceramic sintered body to which no auxiliary component is added, as proposed in JP-A-5-117038, is desirable.

Further, the aluminum nitride sintered body is
The thermal conductivity is 80W from the point of heat uniformity and rapid heating of the susceptor.
/ M · K or more, particularly preferably 100 W / m · K or more.

The aluminum nitride sintered body is formed by mixing aluminum nitride raw material powder with the above-mentioned sintering aid into a desired shape, and then forming it in a non-oxidizing atmosphere such as nitrogen at 1600 to 1950 ° C. It is obtained by firing at the temperature of.

Next, the conductive layer 3 provided on the surface of the substrate 2 is
Molybdenum (Mo) is 70 to 95% by weight, manganese oxide (MnO) is 2 to 20% by weight, and silica (SiO ₂ ) is 3%.
It is deposited by metallizing an alloy of about 15% by weight. In particular, manganese oxide (MnO) is used for the purpose of diffusing an oxide layer of manganese (Mn) into the substrate 1 to improve adhesion. Content of 3 to 15% by weight
Is desirable.

On the other hand, the insulating layer 4 made of a film mainly composed of aluminum nitride formed by the vapor phase synthesis method is 99%.
Although it is highly pure as described above, AlON containing oxygen may coexist in the insulating layer 4 during the formation process, and the amount of oxygen is 20%.
If it exceeds 30 atomic%, the adhesion of the base material to the aluminum nitride sintered body may decrease, so it is desirable to control the oxygen content to 20 atomic% or less.

The thickness of the insulating layer 4 made of a film mainly composed of aluminum nitride is preferably in the range of 0.001 to 1.0 mm, preferably 0.01 to 0.8 mm, particularly preferably 0.1. The range is up to 0.6 mm.

The reason for this is that when the thickness is less than 0.001 mm, the withstand voltage is so small that dielectric breakdown occurs and the durability deteriorates.
It takes a long time to form, resulting in poor productivity.

The insulating layer 4 mainly composed of aluminum nitride has a high purity and a thermal conductivity of 60 W / mK or more,
Particularly, 80 W / m · K or more is more desirable.

Further, according to the present invention, a heat generating circuit 5 for keeping the temperature of the silicon wafer is built in the inside of the substrate 2, and the heat generating circuit 5 is made of Ag, W, Mo, C, TiN, P.
It is desirable to form the silicon wafer with a heating resistor such as d, WC, or Ni so that the silicon wafer can be uniformly kept warm.
W, Mo, T
iN etc. are mentioned.

Further, the heat generating circuit 5 can be integrated by printing the heat generating resistor in a predetermined pattern on a molded body mainly made of aluminum nitride and then simultaneously firing it under the firing conditions. It is effective to add a small amount of aluminum nitride or a sintering aid component to the paste used for printing to enhance the adhesion between the aluminum nitride sintered body and the heating circuit 5.

The insulating layer 4 is formed by a known vapor phase synthesis method, for example, a PVD method such as sputtering or ion plating, plasma CVD, photo CVD, MO (Metal-O).
It is easily formed by a CVD method such as organic (CVD).

Next, in evaluating the electrostatic chuck of the present invention, first, aluminum nitride powder was used and yttria (Y ₂
2% by weight of O ₃ ) was added and mixed to form a raw material into a sheet, and a W paste containing 2% by weight of aluminum nitride was used on the surface of the sheet-shaped compact by a screen printing method to generate heat with a thickness of 25 μm. A circuit pattern is formed, laminated with other sheet-shaped compacts similar to the above sandwiched, and fired at a temperature of 1750 ° C. in a nitrogen atmosphere to sinter aluminum nitride with a thickness of about 5 mm and incorporating a heating circuit. A disk of the body was made.

The thermal conductivity of the obtained aluminum nitride sintered material was measured by the laser flash method.
It was 172 W / m · K under the condition of mm.

Next, a conductive layer made of a Mo--Mn alloy having a composition shown in Table 1 and having a thickness of 20 to 40 μm was formed on the disk by a metallizing method in the shape of the electrode pattern of the electrostatic chuck.

After that, the disk on which the conductive layer was adhered and formed was subjected to CV.
Using the D treatment furnace, the insulating layers of various thicknesses were coated by the thermal CVD method under the raw material gas and temperature conditions shown in Table 1 to prepare samples for evaluation.

On the disk of the aluminum nitride sintered material similar to the above, W of 30 atomic% and aluminum nitride of 70 atomic% were formed.
A sample in which an electrode pattern similar to the above was prepared by using a paste consisting of atomic%, baked at a temperature of 200 ° C. in a nitrogen atmosphere furnace to form a conductive layer, and then covered with an insulating layer by a thermal CVD method. Was used as a comparative example.

[0034]

[Table 1]

In the obtained sample for evaluation, after separately removing the substrate by polishing, the oxygen content of the insulating layer was measured by the combustion analysis method.

The thickness of the insulating layer was measured with a scanning electron microscope after cutting the evaluation sample.

The adhesion of the insulating layer was evaluated by repeating a heat cycle from room temperature to 800 ° C. three times, cutting the sample for evaluation together with the substrate, and visually inspecting the cut surface with a stereoscopic microscope and a scanning electron microscope. The case where peeling or cracking was not observed at all in the insulating layer or the conductive layer was evaluated as ◯, and even a part thereof was evaluated as x.

[0038]

[Table 2]

As is clear from the results shown in Tables 1 and 2,
Sample Nos. 14, 19, 24 with oxygen content exceeding 20 atomic%
In the sample numbers 29, 30, and 31 of Comparative Example, peeling phenomenon of the conductive layer and the insulating layer was observed, and the adhesion was poor. On the other hand, all the samples according to the present invention had excellent adhesion of the conductive layer and the insulating layer to the substrate, no peeling or cracking was observed, and there was no dielectric breakdown.

[0040]

As described above, in the electrostatic chuck according to the present invention, the conductive layer and the insulating layer forming the electrostatic chuck are not peeled off during operation in the semiconductor manufacturing process, and there is a risk of contamination by impurities and the like. In addition, it is possible to obtain an electrostatic chuck that exhibits excellent reliability and stability even at high temperatures for a long period of time, and does not require the use of an extremely high-purity raw material, and that has a low manufacturing cost.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a typical structure of an electrostatic chuck of the present invention.

[Explanation of symbols]

 1 Electrostatic Chuck 2 Base 3 Conductive Layer 4 Insulating Layer 5 Heating Circuit

Claims (2)

[Claims] 1. A conductive layer containing molybdenum (Mo) and manganese (Mn) as main components is deposited on the surface of a substrate made of an aluminum nitride sintered body, and the oxygen content is at least on the conductive layer. Is less than 20 atomic% and the thickness is 0.001
An electrostatic chuck having an insulating layer obtained by coating a film mainly composed of aluminum nitride of about 1.0 mm by a vapor phase synthesis method. 2. A conductive layer containing molybdenum (Mo) and manganese (Mn) as main components is deposited on the surface of a substrate made of an aluminum nitride sintered body, and the oxygen content is at least on the conductive layer. Is less than 20 atomic% and the thickness is 0.001
An electrostatic chuck having an insulating layer obtained by coating a film mainly composed of aluminum nitride having a thickness of up to 1.0 mm by a vapor phase synthesis method, and incorporating a heating circuit in the substrate.