KR20080046785A - Aluminum nitride sintered body and method of forming the same - Google Patents

Abstract

An aluminum nitride sintered body for an electrostatic chuck is provided to obtain a predetermined range of volume resistivity with respect to an applied electric field, and a method of forming the aluminum nitride sintered body for an electrostatic chuck is provided. An aluminum nitride sintered body for an electrostatic chuck comprises 0.1 to 1.0 wt.% of chromium oxide, and aluminum nitride as a principal component. The aluminum nitride sintered body has less than 5% of the volume resistivity variation with respect to an electric field of 100 to 3000 V/mm. The aluminum nitride sintered body has a volume resistivity of 1x10^13 to 1x10^15 Фcm. An aluminum nitride sintered body for an electrostatic chuck comprises 0.1 to 1.0 wt.% of chromic acid, 1.0 to 3.0 wt.% of yttrium oxide, and aluminum nitride as a principal component. A method of forming an aluminum nitride sintered body for an electrostatic chuck comprises the steps of: preparing an aluminum nitride powder as a principal raw material; mixing the aluminum nitride powder with a raw material powder containing 0.1 to 1.0 wt.% of chromic acid; and firing the raw material powder.

Description

Aluminum nitride sintered body for electrostatic chuck and its formation method {ALUMINUM NITRIDE SINTERED BODY AND METHOD OF FORMING THE SAME}

1 to 5 are graphs showing the volume resistivity with respect to the applied electric field in Examples 1 to 6 and Comparative Examples 1 to 8 of the present invention.

The present invention relates to an aluminum nitride sintered body for an electrostatic chuck and a method of forming the same. In more detail, this invention relates to the aluminum nitride sintered compact used for the electrostatic chuck which supports a semiconductor wafer, and its formation method.

Background Art A correction chuck that supports a semiconductor substrate or a glass substrate is used in a semiconductor manufacturing process or a liquid crystal manufacturing process. The electrostatic chuck can be categorized as using the Coulomb force and the Johnson-Rahbek's force.

An electrostatic chuck using a coulomb force fixes the wafer by using electrostatic attraction between particles having different charges on the upper and lower surfaces of the dielectric. In this case, the dielectric is preferably 1 × 10 ¹⁵ cm 3 or more. However, as the semiconductor substrate or the glass substrate is enlarged, there is a problem that a sufficiently large electrostatic attraction force cannot be uniformly formed on the entire wafer contact surface.

An electrostatic chuck using the Johnsen Lavec force can provide sufficient adsorption force using a dielectric having a relatively low volume resistance, for example, a volume resistivity of 1 × 10 ⁸ to 1 × 10 ¹⁵ cm 3. However, when the volume resistance of the dielectric is 1 × 10 ⁸ Pa or less, leakage current may occur. Therefore, it is necessary that the volume resistivity of the dielectric is maintained in the range of 1 × 10 ¹¹ to 1 × 10 ¹⁵ Ωcm.

In addition, when a predetermined voltage is applied to the electrostatic chuck, the leakage current may increase nonlinearly. The leakage current I and the applied voltage V at this time are as shown in Equation 1 below.

Equation 1

I = k × V ^α (where I is the leakage current, V is the applied voltage, α is the nonlinear coefficient, and k is the proportional constant).

In the case of Equation 1, it is preferable that the value of the nonlinear coefficient, which is the increase coefficient of the leakage current with respect to the applied voltage, has a value of 1.0 or less.

Accordingly, it is an object of the present invention to substantially eliminate one or more problems and limitations of the prior art.

One object of the present invention is to provide an aluminum nitride sintered body for an electrostatic chuck which can have a range of volume resistivity with respect to an applied electric field.

It is another object of the present invention to provide a method for forming an aluminum nitride sintered body for an electrostatic chuck which can have a range of volume resistivity with respect to an applied electric field.

An aluminum nitride sintered body for an electrostatic chuck according to one feature for realizing an object of the present invention includes 0.1 to 1.0% by weight of chromium oxide and aluminum nitride as a main component. Here, the aluminum nitride sintered body for electrostatic chuck has a rate of change of volume resistance within 5% for an electric field of 100 to 3000 V / mm. In addition, the aluminum nitride sintered body for electrostatic chucks has a volume resistivity of 1 × 10 ¹³ to 1 × 10 ¹⁵ cm 3.

An aluminum nitride sintered body for an electrostatic chuck according to another feature for realizing an object of the present invention includes 0.1 to 1.0 wt% of chromic acid, 1.0 to 3.0 wt% of yttrium oxide and aluminum nitride as a main component. Here, the aluminum nitride sintered body for electrostatic chuck has a rate of change of volume resistance within 5% for an electric field of 100 to 3000 V / mm. In addition, the aluminum nitride sintered body for electrostatic chucks has a volume resistance of 1 × 10 ¹³ to 1 × 10 ¹⁵ cm 3.

In the method for forming an aluminum nitride sintered body for an electrostatic chuck according to another aspect for realizing an object of the present invention, first, aluminum nitride powder, which is a main raw material, is prepared. Thereafter, a raw material powder containing 0.1 to 1.0% by weight of chromic acid is formed in the aluminum nitride powder, and then the raw material powder is fired to produce an aluminum nitride sintered body for electrostatic chuck. Here, the aluminum nitride sintered body for electrostatic chuck has a rate of change of volume resistance within 5% for an electric field of 100 to 3000 V / mm. In addition, the aluminum nitride sintered body for electrostatic chucks has a volume resistance of 1 × 10 ¹³ to 1 × 10 ¹⁵ cm 3.

According to the present invention, the aluminum nitride sintered body for electrostatic chuck comprising 0.1 to 1.0 wt% of chromium oxide and aluminum nitride as a main component has a volume resistivity of 1 × 10 ¹³ to 1 × 10 ¹⁵ Ωcm. The aluminum nitride sintered body for electrostatic chuck has excellent leakage current characteristics.

Aluminum Nitride Sintered Body

The aluminum nitride sintered body for electrostatic chucks according to the present invention contains aluminum nitride and 0.1 to 1.0% by mass of chromium oxide as main components. The aluminum nitride sintered compact according to the present invention has a volume resistivity of 1 × 10 ¹³ cm 3 to 1 × 10 ¹³ cm 3.

When the said chromium oxide is less than 0.1 mass%, the volume resistivity of an aluminum nitride sintered compact will fall to less than 1 * 10 <^13> Pacm. Moreover, when the said chromium oxide exceeds 1.0 mass%, the volume resistivity of an aluminum nitride sintered compact will also fall to less than 1 * 10 <^13> Pacm. Further, when an electric field of 100 and 3000 V / mm is applied to the aluminum nitride sintered body, as the ratio of the volume resistivity of the aluminum nitride sintered body including less than 0.1% by mass or more than 1.0% by mass of chromium oxide has a relatively large value, Therefore, the rate of change of volume resistivity is relatively large.

The aluminum nitride sintered body according to the present invention has a volume resistivity of 1 × 10 ¹³ cm 3 to 1 × 10 ¹⁵ cm 3. Also, when an electric field of 100 and 3000 V / mm is applied to the aluminum nitride sintered body, the ratio of the volume resistivity of the aluminum nitride sintered body to the applied electric field has a relatively large value, so that the rate of change of the volume resistivity is relatively high. As big as.

On the other hand, in order to improve the sinterability of the aluminum nitride sintered compact, the aluminum nitride sintered compact includes 0.1 to 1.0 mass% of chromium oxide, 1.0 to 3.0 mass% of yttrium oxide, and aluminum nitride as a main component.

When yttrium oxide is contained below 1.0 mass%, the sinterability of an aluminum nitride sintered compact will deteriorate and a relative density will fall. Also, when yttrium oxide is contained in the aluminum nitride sintered body by more than 3.0 mass%, the volume resistivity increases, while when 100 and 3000 V / mm electric fields are applied to the aluminum nitride sintered body, aluminum nitride for each applied electric field As the ratio between the volume resistivity of the sintered body has a relatively large value, the rate of change of the volume resistivity is relatively large.

Method of Forming Aluminum Nitride Sintered Body

First, chromium oxide powder is prepared to include 0.1 to 1.0 mass% of chromium oxide in the total powder weight before sintering, and the chromium oxide is mixed with the aluminum nitride powder in a solvent, mixed, and then pulverized dry. Anhydrous ethanol is mentioned as an example of a solvent.

When the said chromium oxide is less than 0.1 mass%, the volume resistivity of an aluminum nitride sintered compact will fall to less than 1 * 10 <^13> Pacm. Moreover, when the said chromium oxide exceeds 1.0 mass%, the volume resistivity of an aluminum nitride sintered compact will also fall to less than 1 * 10 <^13> Pacm. Further, when an electric field of 100 and 3000 V / mm is applied to the aluminum nitride sintered body, as the ratio of the volume resistivity of the aluminum nitride sintered body including less than 0.1% by mass or more than 1.0% by mass of chromium oxide has a relatively large value, Therefore, the rate of change of volume resistivity is relatively large.

The aluminum nitride sintered body according to the present invention has a volume resistance of 1 × 10 ¹³ cm 3 to 1 × 10 ¹⁵ cm 3. Also, when an electric field of 100 and 3000 V / mm is applied to the aluminum nitride sintered body, the ratio of the volume resistivity of the aluminum nitride sintered body to the applied electric field has a relatively large value, so that the rate of change of the volume resistivity is relatively high. As big as.

On the other hand, in order to improve the sinterability of the aluminum nitride sintered compact, the aluminum nitride sintered compact includes 0.1 to 1.0 mass% of chromium oxide, 1.0 to 3.0 mass% of yttrium oxide, and aluminum nitride as a main component.

When yttrium oxide is contained below 1.0 mass%, the sinterability of an aluminum nitride sintered compact will deteriorate and a relative density will fall. Also, when yttrium oxide is contained in the aluminum nitride sintered body by more than 3.0 mass%, the volume resistivity increases, while when 100 and 3000 V / mm electric fields are applied to the aluminum nitride sintered body, aluminum nitride for each applied electric field As the ratio between the volume resistivity of the sintered body has a relatively large value, the rate of change of the volume resistivity is relatively large.

Thereafter, the powder for aluminum nitride sintered compact is sintered and cooled to obtain an aluminum nitride sintered compact according to the present invention.

In the sintering step, the sintering temperature is preferably 1,700 to 1,850 ° C, more preferably 1,750 to 1,800 ° C. If the sintering holding time is less than 1 hour, the relative density of the aluminum nitride sintered compact is lowered. If the sintering holding time is more than 10 hours, an economic loss may be caused by an increase in the process time.

The aluminum nitride sintered body according to the present invention thus prepared has a volume resistivity in the range of 1 × 10 ¹³ cm 3 to 1 × 10 ¹⁵ cm 3 at room temperature. In addition, when an electric field of 100 and 3000 V / mm is applied to the aluminum nitride sintered body, the ratio between the volume resistivity for each applied electric field becomes a relatively low value, whereby the aluminum nitride sintered body having a relatively low rate of change in volume resistivity Is prepared.

nitrification  Manufacture of Aluminum Sintered Body

<Example 1>

High purity reduced aluminum nitride powder was used. The aluminum nitride powder had a purity excluding 99.9% or more of oxygen and had an average particle diameter of 1.29 μm. The main impurities of the aluminum nitride powder include 0.84 wt% oxygen, 31.0 × 10 ⁻³ wt% carbon, 0.8 × 10 ⁻³ wt% potassium, 0.9 × 10 ⁻³ wt% silicon, and 0.4 × 10 ⁻³ wt% iron. It became.

1.0% by weight of yttrium oxide (Y ₂ O ₃ ) and 0.1% by weight of chromium oxide (Cr ₂ O ₃ ) were mixed with the excess aluminum nitride powder, and anhydrous ethanol was mixed with a solvent to make a pot made of nylon and alumina balls. Powder mixed in the above composition was wet mixed for 20 hours. After mixing, the slurry was extracted, dried at 80 ° C. in a dryer, and then the dried body was pulverized using alumina induction. The pulverized dry powder was sieved using an 80 mesh body to prepare a powder for aluminum nitride sintered body.

The powder for aluminum nitride sintered compact was charged into a graphite mold having a diameter of Φ 210 mm, which was calcined at a sintering temperature of 1,750 ° C. under a press pressure of 0.1 MPa in a high temperature pressurized sintering furnace for 3 hours, followed by natural cooling. As a result, an aluminum nitride sintered body was produced.

<Examples 2 and 3>

An aluminum nitride sintered body was manufactured in the same manner as in Example 1, except for the content of chromium oxide. The content of each component according to each example is shown in Table 1 below.

<Comparative Examples 1 and 2>

An aluminum nitride sintered body was manufactured by the same method as Example 1 except for the content of chromium oxide (Cr ₂ O ₃ ). The content of each component according to each comparative example is shown in Table 1 below.

TABLE 1

Cr ₂ O ₃ content Y ₂ O ₃ content Aluminum nitride content Example 1 0.1 1.0 98.9 Example 2 0.5 1.0 98.5 Example 3 1.0 1.0 98.0 Comparative Example 1 0.05 1.0 98.95 Comparative Example 2 1.5 1.0 98.5

(Unit: weight%)

<Examples 4 to 6>

An aluminum nitride sintered body was manufactured in the same manner as in Example 1, except for the contents of chromium oxide and yttrium oxide. The content of each component according to each example is shown in Table 2 below.

<Comparative Examples 3 to 8>

An aluminum nitride sintered body was manufactured in the same manner as in Example 1, except for the contents of chromium oxide and yttrium oxide. The content of each component according to each comparative example is shown in Table 2 below.

TABLE 2

Cr ₂ O ₃ content Y ₂ O ₃ content Aluminum nitride content Example 4 0.1 3.0 96.9 Example 5 0.5 3.0 96.5 Example 6 1.0 3.0 96.0 Comparative Example 3 0.1 0.5 94.9 Comparative Example 4 0.5 0.5 94.5 Comparative Example 5 1.0 0.5 98.5 Comparative Example 6 0.1 5.0 94.9 Comparative Example 7 0.5 5.0 94.5 Comparative Example 8 1.0 5.0 94.0

(Unit: weight%)

Experimental Example - nitrification  Volume of aluminum sintered body Resistivity  evaluation

The volume resistivity of the aluminum nitride sintered compact for electrostatic chuck was measured using the aluminum nitride sintered compact manufactured in the above examples and comparative examples. The results are shown in Table 3 and FIGS. 1 to 5. Specifically, test specimens having a diameter of 210 mm and a thickness of 0.5 mm were manufactured using the aluminum nitride sintered bodies prepared in Examples 1 to 6 and Comparative Examples, and the electrode shapes were made of a main electrode diameter of 26 mm and a protection electrode diameter of 38 mm. , An electric field was applied. In this case, the electric field was set to 100, 250, 500, 1,000, 2,000 and 3,000 V / mm, the voltage application time was measured based on the volume resistivity of 60 seconds. Furthermore, after measuring the leakage current value according to the applied voltage, the nonlinear coefficient α was obtained as the slope of the linear function obtained by using the least-squares method for the log value of the leakage current value.

TABLE 3

(Unit: mm)

Referring to Table 3 and FIGS. 1 to 5, in Comparative Examples 1 and 2 having less than 0.1 wt% or more than 1.0 wt% of chromium oxide, the aluminum nitride sintered body including 0.1 wt% to 1.0 wt% of chromium oxide may be used. In comparison, it can be seen that the volume resistivity is significantly reduced. In particular, when applied to the specimen of the aluminum nitride sintered body in the electric field of 3,000 V / mm, it can be seen that the volume resistivity is significantly reduced compared to the case of the electric field of 500 V / mm. Specifically, when an electric field of 500 V / mm is applied to the aluminum nitride sintered body according to Comparative Example 1, it has a volume resistivity of 2.93 × 10 ¹⁴ Ωcm, whereas when an electric field of 3,000 V / mm is applied, 8.95 × 10 ¹² Ω It has a volume resistivity of cm. Thus, the ratio of the volume resistivity of each of the electric fields of 500 V / mm and 3,000 V / mm is about 32.7 times. When the high electric field is applied to the aluminum nitride sintered body according to Comparative Example 1, it can be seen that the volume resistivity is significantly reduced. When an electric field of 500 V / mm is applied to the aluminum nitride sintered body according to Comparative Example 2, it has a volume resistivity of 2.93 × 10 ¹⁴ Ωcm, whereas when an electric field of 3,000 V / mm is applied, 8.95 × 10 ¹² Ωcm It has a volume resistivity of. Thus, the ratio of the volume resistivity of each of the electric fields of 500 V / mm and 3,000 V / mm is about 199 times. When a high electric field is applied to the aluminum nitride sintered compact according to Comparative Example 2, it can be seen that the volume resistivity is significantly reduced.

Meanwhile, in Comparative Examples 3 to 5 and Comparative Examples 6 to 8, which contain less than 1.0 wt% or more than 3.0 wt% of yttrium oxide, the aluminum nitride sintered body comprising 1.0 wt% to 3.0 wt% of yttrium oxide according to the present invention In comparison, it can be seen that the volume resistivity is significantly reduced. In particular, when applied to the specimen of the aluminum nitride sintered body in the electric field of 3,000 V / mm, it can be seen that the volume resistivity is significantly reduced compared to the case of the electric field of 500 V / mm.

In the case of an aluminum nitride sintered body containing less than 1.0 wt% of yttrium oxide, when an electric field of 500 V / mm is applied to the aluminum nitride sintered body according to Comparative Example 3, it has a volume resistivity of 2.01 × 10 ¹⁴ Ωcm, When an electric field of mm is applied, it has a volume resistivity of 8.91 × 10 ¹³ Ωcm. Thus, the ratio of the respective volume resistivity to the electric fields of 500 V / mm and 3,000 V / mm appears about 2.26 times. When a high electric field is applied to the aluminum nitride sintered body according to Comparative Example 3, it can be seen that the volume resistivity is significantly reduced. When an electric field of 500 V / mm is applied to the aluminum nitride sintered body according to Comparative Example 4, it has a volume resistivity of 2.13 × 10 ¹⁴ Ωcm, whereas when an electric field of 3,000 V / mm is applied, it is 9.26 × 10 ¹³ Ωcm It has a volume resistivity. Thus, the ratio of the respective volume resistivity to the electric fields of 500 V / mm and 3,000 V / mm appears about 2.30 times. When the high electric field is applied to the aluminum nitride sintered body according to Comparative Example 4, it can be seen that the volume resistivity is significantly reduced. When an electric field of 500 V / mm is applied to the aluminum nitride sintered body according to Comparative Example 5, it has a volume resistivity of 2.18 × 10 ¹⁴ Ωcm, while when an electric field of 3,000 V / mm is applied, it is 9.56 × 10 ¹³ Ωcm It has a volume resistivity. Thus, the ratio of the respective volume resistivity to the electric fields of 500 V / mm and 3,000 V / mm appears about 2.28 times. When the high field is applied to the aluminum nitride sintered body according to Comparative Example 5, it can be seen that the volume resistivity is significantly reduced.

In the case of the aluminum nitride sintered body containing more than 3.0 wt% of yttrium oxide, when an electric field of 500 V / mm is applied to the aluminum nitride sintered body according to Comparative Example 6, it has a volume resistivity of 2.31 × 10 ¹⁵ Ωcm, while being 3,000 V / When an electric field of mm is applied, it has a volume resistivity of 9.70 × 10 ¹⁴ Ωcm. Thus, the ratio of the volume resistivity of each of the electric fields of 500 V / mm and 3,000 V / mm is about 2.38 times. When the high electric field is applied to the aluminum nitride sintered body according to Comparative Example 6, it can be seen that the volume resistivity is significantly reduced. When an electric field of 500 V / mm is applied to the aluminum nitride sintered body according to Comparative Example 7, it has a volume resistivity of 2.35 × 10 ¹⁵ Ωcm, whereas when an electric field of 3,000 V / mm is applied, it is 9.90 × 10 ¹⁴ Ωcm It has a volume resistivity. Thus, the ratio of the volume resistivity of each of the electric fields of 500 V / mm and 3,000 V / mm appears about 2.37 times. When the high electric field is applied to the aluminum nitride sintered body according to Comparative Example 7, it can be seen that the volume resistivity is significantly reduced. When an electric field of 500 V / mm is applied to the aluminum nitride sintered body according to Comparative Example 8, it has a volume resistivity of 2.65 × 10 ¹⁵ cm 3, while an electric field of 3,000 V / mm is 8.38 × 10 ^{14 m} It has a volume resistivity. Thus, the ratio of the volume resistivity of each to the electric fields of 500 V / mm and 3,000 V / mm appears about 3.16 times. When a high electric field is applied to the aluminum nitride sintered body according to Comparative Example 8, it can be seen that the volume resistivity is significantly reduced.

On the other hand, the aluminum nitride sintered body according to the present invention has a nonlinear coefficient of 0.1 or less. Therefore, when the applied voltage increases, the increase of the leakage current can be relatively lowered.

As described in detail above, according to the present invention, the aluminum nitride sintered body for electrostatic chuck containing 0.1 to 1.0 wt% of chromium oxide and aluminum nitride as a main component has a volume resistivity of 1 × 10 ¹³ to 1 × 10 ¹⁵ cm 3. In addition, when an electric field of 500 and 3000 V / mm is applied to the aluminum nitride sintered body, the ratio between the volume resistivity for each applied electric field becomes a relatively low value, whereby the aluminum nitride sintered body having a relatively low rate of change in the volume resistivity Is prepared.

In addition, the aluminum nitride sintered body for electrostatic chuck has excellent leakage current characteristics.

In the detailed description of the present invention described above with reference to the preferred embodiments of the present invention, those skilled in the art or those skilled in the art having ordinary skill in the art will be described in the claims to be described later It will be understood that various modifications and variations can be made in the present invention without departing from the scope of the present invention.

Claims (9)

An aluminum nitride sintered body for electrostatic chuck comprising 0.1 to 1.0% by weight of chromium oxide and aluminum nitride as a main component. The aluminum nitride sintered body for electrostatic chuck according to claim 1, having a rate of change of volume resistance within 5% with respect to an electric field of 100 to 3000 V / mm. The aluminum nitride sintered body for electrostatic chuck according to claim 1, which has a volume resistance of 1 × 10 ¹³ to 1 × 10 ¹⁵ Ωcm. An aluminum nitride sintered body for electrostatic chuck comprising 0.1 to 1.0% by weight of chromic acid, 1.0 to 3.0% by weight of yttrium oxide and aluminum nitride as a main component. 5. The aluminum nitride sintered body for electrostatic chuck according to claim 4, having a rate of change of volume resistance within 5% for an electric field of 100 to 3000 V / mm. The aluminum nitride sintered body for electrostatic chuck according to claim 4, which has a volume resistance of 1 × 10 ¹³ to 1 × 10 ¹⁵ Ωcm. Preparing a main material of aluminum nitride powder; Molding raw material powder containing 0.1 to 1.0 wt% chromic acid in the aluminum nitride powder; And Method of forming an aluminum nitride sintered body for electrostatic chuck comprising the step of firing the raw material powder. The method of forming an aluminum nitride sintered body for electrostatic chuck according to claim 7, characterized in that it has a rate of change of volume resistance within 5% for an electric field of 100 to 3000 V / mm. The method for forming an aluminum nitride sintered body for electrostatic chuck according to claim 7, which has a volume resistivity of 1 × 10 ¹³ to 1 × 10 ¹⁵ cm 3.

Images