JP2000143361A - Ceramic structure and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a ceramic structure having a high joint strength and good joint characteristics substantially without causing irregularity by joining a plurality of ceramic members to each other through a joining material having a specific thermal expansion coefficient ratio to those of the ceramic members. SOLUTION: This ceramic structure is obtained by baking a joining material having a thermal expansion coefficient of 90-97% based on those of a plurality of ceramic members on the joining surfaces of the ceramic members, polishing the surfaces in a flatness degree of <=50 μm and a joining material thickness of 20-50 μm, pressing the faced surfaces of the members onto each other and subsequently thermally treating the pressed members at 700-1,000 deg.C to join each other. The thermal expansion coefficient of the joining material is obtained by using at least two of SiO2, Al2O3, B2O3, Bi2O3, BaO and ZnO. For example, a ceramic plate 1 for producing semiconductors can be obtained as a hollow lightweight ceramic structure 4 by separately producing a ceramic ceiling plate 2 and a box 3 and subsequently joining the members.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic structure formed by joining a plurality of ceramic members and a method for manufacturing the same.

[0002]

2. Description of the Related Art Ceramics are lightweight, high rigidity, high strength,
It is widely used as a structural member, a wear-resistant member, and a contact-resistant member by utilizing its high hardness and excellent heat resistance and corrosion resistance.

At present, in the semiconductor industry, miniaturization is progressing with high integration of LSI, and the minimum line width of a pattern is decreasing year by year. Although the current design line width is 0.35 μm, 199
0.25 μm in 8 years, 0.18 μm in 2001,
It is expected to shift to 0.13 μm in 2004. The exposure method used for device fabrication is currently a light exposure method, but it is said that in the future, it will be changed to an electron beam drawing method and an X-ray drawing method capable of high-accuracy and high-quality processing. .

Further, the wafer size is currently 200
The size is planned to be increased from 2000 mm to 300 mm in 2000 or 1999. In order to increase the drawing area as the size increases, two points of higher precision and higher speed drawing are desired for the semiconductor manufacturing apparatus.

As shown in FIG. 5, the exposure apparatus used at this time has an illumination engineering system 11 as a light source, a reticle stage 12 having a quartz mask (reticle) mounted thereon, and
It comprises a light guiding barrel 13, a wafer stage 14 on which a silicon wafer is mounted, a barrel base 15 for supporting the reticle stage and the barrel, and a base 16 for supporting the entire apparatus.

[0006] Currently, the mainstream of the exposure apparatus employs a reduced projection exposure system. The exposure apparatus sequentially exposes the surface of the wafer several tens of times while moving the wafer. For this reason, in the exposure apparatus, an element that moves the wafer stepwise at a high speed and positions the wafer with high accuracy is an important component for improving the drawing speed. To shorten the positioning time, it can be said that a specific approach is to reduce the weight of the mechanical system itself and to improve the accuracy of the guide mechanism.

Further, as shown in F = 1/2 · mv ^{2 a} F a: inertia force, reduction of weight is synonymous with reduction of inertia force.

More specifically, the following two points can be considered as options for reducing the weight of the mechanical system. (1) A light specific gravity material may be used as a member constituting the mechanical system. For example, a metal material has been replaced with a ceramic material. (2)
What is necessary is just to change the design of the member and reduce the weight. For example, it is seen that the member is designed to have a hollow structure or a hollow structure. In addition, there are some cases where both (1) and (2) are used together.

As described above, ceramics have high strength and high hardness, but are difficult-to-cut materials. Therefore, the actual cost of the product is higher than that of a metal or a resin. One of the effective methods to keep the product cost low is to reduce the number of processing steps or the amount of processing, and a specific method is to join together those formed in a simple shape. In order to expand the uses of ceramics, methods for joining ceramics are being studied.

In recent years, research has been applied to the joining of ceramics using a hot press method (HP method) or hot isostatic pressing (HIP method), which is useful as a method for firmly joining metals or a metal and ceramics. Is being promoted.

[0011] The HP method is a method in which members to be joined are sandwiched by a press punch portion, and are heated to a high temperature while being uniaxially pressed by a punch to join. The HIP method is a method of using a gas as a pressurized medium, compressing a member to be joined in a high-pressure container formed in a high-pressure cylinder while heating and joining the members. These studies are based on C.I. Scoff et al. In Japan, research cases are found in Japanese Patent Application Laid-Open No. Hei 5-97530.

As another method, there is an oxide solder method in which an oxide is used as a bonding medium for bonding. There are various types of oxide solders, which contain a large amount of PbO and have a melting point of 300 ° C to 40 ° C.
From a low melting point solder of about 0 ° C or lower,
₂ O ₃ , CaO, MgO, ZrO ₂ , Y ₂ O ₃ , ThO
_2. There are various types of solders having a melting point of 1200 ° C. to 2000 ° C. or higher, whose main components are Si ₃ N ₄ , SiC, and AlN. The general procedure of the soldering method is to apply solder to the joint surface of the object to be joined, and to press the joint surface of the member that has been processed in the same manner, to approximately 500 to 1200 ° C.
This is a method of performing heat treatment in an air atmosphere.

[0013] In contrast to the above-mentioned joining of porcelains, in the joining method using the compacts before sintering, the compacts obtained by the casting method are combined with the pre-molding precursor, the slurry, as a joining medium. There is a joining method known as a joining method of a handle of a coffee cup, which is called a sticking method or a sticking method.

[0014]

The problems of the above joining method will be described below.

In the case of HP or HIP, the inner diameter of general equipment is about φ300 to 400 mm, and only products with dimensions smaller than this are obtained. With respect to this equipment inner diameter, there has been a problem that products which can be applied to members for semiconductor manufacturing equipment whose mainstream is currently shifting to 300 mm wafers are limited.

In the oxide solder method, defects in the bonding layer due to bubbles such as air and moisture, or variations in bonding characteristics due to aggregation of solder components are apt to occur. There was a problem that it was difficult.

The notching method, which is a method of joining the molded bodies, is a manufacturing method using a molded body by casting, and thus has a problem in that the shape of the molded body is limited to a shape applicable to the casting.

As described above, the conventional joining method cannot cope with products having various dimensions and shapes, and has a problem that the joining characteristics vary.

[0019]

According to the present invention, in order to solve the above-mentioned problems, the size of the product is reduced by using a heat treatment in an air atmosphere and under normal pressure.
The following specifications were established in order to ease the restriction on the shape by using ceramic sintered bodies, and to provide products with good bonding characteristics and less variation.

In the present invention, the joint surface of a plurality of ceramic members is covered with an oxide solder as a joining material, then the thickness and flatness of the solder layer are adjusted, and heat treatment is performed with the joined surfaces facing each other. Specifically, defects due to air and moisture can be reduced by setting the heat treatment temperature sufficiently higher than the melting point of the solder in the open state in order to smoothly transfer from the inside of the solder to the surface. Aggregation of the solder can be suppressed by controlling the thickness of the solder to less than 0.2 mm and applying it to the surface. With the specifications up to this point, defects and agglomeration in the solder layer can be solved.

Next, the surface of the bonding precursor is set to a flatness of 50.
polished to a solder layer thickness of less than 20 μm and a solder layer thickness of less than 700 μm.
By performing the heat treatment at 1100 ° C., a bonded body free from defects and aggregation can be obtained.

Further, the present invention provides a method for manufacturing a semiconductor device using the above-mentioned bonding material as a Nasu solder, which has a thermal expansion coefficient of 90 to 97% with respect to a ceramic member, such as SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ ,
By using a bonding material composed of at least two of Bi ₂ O ₃ , BaO, and ZnO, a stable bonded body can be obtained.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The structure 1 shown in FIG. 1 (a) is a ceramic plate used for a stage for a semiconductor manufacturing apparatus or the like. As shown in FIG. Then, the ceramic structure 4 of the present invention can be obtained by dividing and manufacturing into a box material 3 and joining as shown in FIG. The ceramic structure 4 can be a hollow and lightweight member.

The structure 1 shown in FIG. 2 (a) is obtained by joining a wiring member 5 to the same stage as that shown in FIG. 1, and this is made of ceramics as shown in FIGS. 2 (b) and 2 (c). The ceramic structure 4 of the present invention can be obtained by separately manufacturing the top plate 2 and the box material 3 and joining them. This is hollow,
Light weight and a compact structure can be obtained by housing the wiring member 5 in the hollow interior.

The structure 1 shown in FIG. 3A is a surface plate, which is divided into a ceramic flat surface plate 6 and a support member 7 as shown in FIGS. 3B and 3C, and joined. By doing so, the ceramic structure 4 of the present invention can be obtained. This reduces the processing cost and raw material loss generated in the integrated manufacturing, makes it possible to supply inexpensive members, and can be used as a support member of a semiconductor manufacturing apparatus.

The structure 1 shown in FIG. 4A is a table used for a stage and a chuck for a semiconductor manufacturing apparatus. As shown in FIGS. 4B and 4C, the structure 1 is provided with a top plate 2 and a groove. The ceramic structure 4 of the present invention can be obtained by separately manufacturing and joining the support 8. This can be a member with an additional function that incorporates a temperature adjustment pipe.

In the above-described ceramic structure 1, the solder constituting the joining material has a coefficient of thermal expansion of 90 to 97% with respect to the coefficient of thermal expansion of the ceramic member to be joined.

Basically, it is desirable that there is no difference in thermal expansion. However, when cooling after the heat treatment, a form in which the ceramic member compresses the solder portion, that is, a bonded body that is stable when the thermal expansion coefficient of the solder is smaller than that of the ceramic is required. It tends to be easily obtained. From this point, the thermal expansion coefficient of the solder is 97% or less of the ceramic member. However, when the difference in thermal expansion becomes large, compression failure occurs. Therefore, the thermal expansion coefficient of the solder is set to 90% or more of the ceramic member.

[0030] For the above reasons, by adopting a structure in which compression is applied to the joining portion, stable joining of ceramics becomes possible.

In order to adjust the thermal expansion coefficient of the solder to the above range, SiO ₂ , Al ₂
Any of at least two of O ₃ , B ₂ O ₃ , Bi ₂ O ₃ , BaO, and ZnO may be used, and the coefficient of thermal expansion of the solder can be freely adjusted by adjusting the ratio of the above components. Can be adjusted.

The final thermal expansion coefficient of the solder is:
It is determined from the composition ratio of each component constituting the solder. For example, since the thermal expansion coefficient of Al ₂ O ₃ is 7 ppm and that of SiO ₂ is 0 ppm, the thermal expansion coefficient of the solder is 3.
If it is desired to be 5 ppm, the composition ratio of Al ₂ O ₃ and SiO ₂ may be 1: 1 by volume.

However, since there is actually a reaction product of each other, accurate calculation requires adding the abundance ratio of the reaction product to the calculation formula.

For the measurement of the coefficient of thermal expansion from the solder itself, a test piece for measurement is cut out together with the joint of the product, and first, the entire coefficient of thermal expansion is measured. Next, the ratio of the total length of the ceramics to be joined to the test piece is determined, and the elongation percentage in the test piece is determined from the coefficient of thermal expansion of the ceramics. Therefore, the difference from the total elongation is the elongation of the bonding layer, and the actual thermal expansion coefficient of the bonding layer can be obtained from the above operation.

The melting point of the solder used for joining is as follows:
It is desirable that the temperature is as low as possible to prevent thermal degradation of the ceramic. For example, in the composition of Al ₂ O ₃ and SiO ₂ ,
If the melting point is not as low as expected,
Adding ₂ O ₃ can lower the melting point of the solder.

As described above, the selection of the solder is made on the basis of the factors of the thermal expansion coefficient and the melting point, and SiO ₂ , Al ₂
A combination of two or more of O ₃ , B ₂ O ₃ , Bi ₂ O ₃ , BaO, and ZnO is effective. As a result of the above combination, it is possible to set a coefficient of thermal expansion of 2.0 to 9.8 ppm and a melting point of 400 to 1100 ° C.

As the target ceramic of the ceramic member in the present invention, oxide ceramics include:
Alumina, zirconia, titania and the like can be mentioned. Non-oxide ceramics include silicon nitride, silicon carbide, sialon, and the like.

Next, the joining method of the present invention will be described.

First, a ceramic member to be joined is prepared. The joining surface of the ceramic member has a flatness of 20 to
Polishing and lapping are performed to 40 μm and a surface roughness Ra of 0.2 to 0.5 μm μm. After processing, the bonding surface is 400 ~ 500 ℃
After the heat treatment, a degreasing treatment is performed using acetone.

Next, in order to adjust the solder into a paste, the resin and the organic solvent are mixed at a powder filling rate of 50 to 60% by volume. The powder filling ratio and the resin / organic solvent ratio are adjusted so that the raw material viscosity becomes 40 to 80 PaS.

Next, a solder is applied to the joint surface. The coating is performed by using a screen of # 100 to # 200 and setting the film pressure to 0.1 to 0.2 mm. After the application, the solder is heat-treated at 700 to 1100 ° C., and the solder is baked on the joined body.

After baking, the joining surface is polished and wrapped to a flatness of less than 50 μm and a solder layer thickness of 20 to 50 μm.
m. After processing, the joint surface is degreased using acetone. After bonding surfaces of the bonding precursor prepared in the above procedure are opposed to each other, heat treatment is performed at 700 to 1100 ° C. to obtain a bonded body.

The ceramic structure of the present invention obtained as described above is used as a member for a semiconductor manufacturing apparatus, such as a stage member, a supporting column, a table, a jig (holder), a guide rail, a slider, and a measuring member. As a member or the like or a general structural member, it can be used for a fiber guide material, a jig or the like.

[0044]

EXAMPLE 1 Alumina ceramics (alumina purity 99.5%, specific gravity 3.85) was used as a test piece of a ceramic member.
The test piece shape was 10 × 10 × 20 mm. Its thermal expansion coefficient is 7.2 × 10 ⁻⁶ / ° C. (measurement range: room temperature to 500
° C). The following bonding was performed, and the quality of the bonded state was determined to be a good bonded body if the bonding area ratio was 95% or more.

The following materials were selected for the oxide solder. The values in parentheses indicate the coefficients of thermal expansion from room temperature to 500 ° C.

ZnO—B ₂ O ₃ —SiO ₂ (4.8
× 10 ⁻⁶ / ° C.) SiO ₂ —BaO—B ₂ O ₃ —Al ₂ O ₃ (6.0
× 10 ⁻⁶ / ° C.) SiO ₂ —B ₂ O ₃ —ZnO—Na ₂ O (6.5
× 10 ⁻⁶ / ° C.) SiO ₂ —B ₂ O ₃ —ZnO—Al ₂ O ₃ —Na ₂ O
(6.9 × 10 ⁻⁶ / ° C.) SiO ₂ —B ₂ O ₃ —Bi ₂ O ₃ —Na ₂ O (8.
(4 × 10 ⁻⁶ / ° C.) As a result of confirming the above temperature conditions that do not cause bubbles without causing agglomeration of the solder, it was confirmed that the temperature was 700 to 1100 ° C. Confirmation was made by observing the joint and judging the presence or absence of a void. For solder aggregation,
It was confirmed that a heating rate of 50 ° C./h was an effective condition. This is considered to be due to the fact that, when the heat treatment temperature is constant, the total amount of heat increases as the heating rate decreases, so that the aggregation of the solder is promoted.

The procedure of the work is such that a solder having a thickness of 0.1 to 0.2 mm is applied to the end face of the test piece by a screen printing method, and then a heat treatment is performed at the above temperature setting. The coating thickness is
When the thickness exceeds 0.2 mm, agglomeration is observed, so that the above conditions were set. Through the above steps, a joining precursor having a solder coating on the surface of the material to be joined is obtained.

Next, the solder film is polished so as to have a flatness of less than 50 μm. It can be expected that the characteristics obtained with the flatness specification of 50 μm will have the same characteristics even under the surface conditions where the flatness becomes even smaller. Finally, the solder coating surfaces of the bonding precursors finished to a film thickness of 20 to 50 μm were opposed to each other, and the bonding treatment was performed under the above-described temperature conditions. The bonding temperature was 800 ° C. The weight was not specifically set. The bonding layer thickness of the obtained bonded body was 30 to 80 μm.

The bending strength of the obtained joined body was measured by a four-point bending test method, and an average value of five samples was obtained. Further, a bonding area ratio (= bonding area / total bonding area) was determined from a bonding layer map obtained by the ultrasonic flaw detection method.

The results are shown in Table 1. As shown in Table 1, a joined body in a good joined state was obtained with the above solder, and the thermal expansion coefficient of the ceramic forming the test piece was 7.2 × 10 ⁻⁶ / ° C.
It can be seen that a solder within the range of 0 to 97% may be used.

As a component of the solder, Al
₂ O ₃ , SiO ₂ , MgO, CaO, Y ₂ O ₃ , B ₂ O
₃ , the thermal expansion coefficient of any of the components such as Bi ₂ O ₃ , ZnO, ZrO ₂ , Na ₂ O, etc.
By adjusting to 97%, a similarly good joined body was obtained.

[0052]

[Table 1]

When the thermal expansion coefficient of the solder is less than 90% or more than 97%, it is considered that the joint is peeled off due to the generation of tensile or compressive stress.
It is considered that such a phenomenon appears as a decrease in the bonding area ratio.

Further, as a comparative example, the same measurement was performed on a joined body which was subjected to a heat treatment simply by sandwiching a solder between test pieces. As shown in Table 2, the strength joint area ratio was a low value.

[0055]

[Table 2]

As a result, the thermal expansion coefficients of 6.5 and 6.9 × 10 ^-6 / ° C.
(For the coefficient of thermal expansion of ceramics, 90
%, 97%), the surface of the material to be joined was coated, then the surface was finished to a flatness of 50 μm, and the surface was pressure-bonded and treated at 800 ° C. to obtain good joining strength.

Example 2 Using the alumina ceramic described in Example 1, FIG.
300 × 280 × 15 mm, thickness 3 mm
Thus, a ceramic structure 1 having a hollow inside was produced.

As a comparative example, a solid body having the same outer diameter was manufactured. When the respective weights and natural frequencies were calculated, as shown in Table 3, the product weight of the ceramic structure of the present invention was 72% of that of the solid body due to hollowing. By further reducing the wall thickness, the weight can be reduced, but the strength and rigidity of the product are expected to decrease, so the wall thickness was limited to 3 mm. In addition, for the joining, the material of Example 1 was selected as the joining material, and heat treatment was performed at 800 ° C. The treatment of the joint surface was also set to a flatness of 20 μm, and the opposed joint specification was used.

As a result of actually measuring the weight and the natural frequency of the actually manufactured ceramic structure, as shown in Table 4, the values were the same as the calculated values shown in Table 3.

[0060]

[Table 3]

[0061]

[Table 4]

Next, the reliability of the obtained ceramic structure was evaluated. In the evaluation, the following thermal cycle test and acceleration test were performed on the ceramic structure, and it was determined whether or not the natural frequency had changed before and after the test.

The heat cycle test was performed at -30 ° C. → room temperature → 80
A heat cycle test of 100 cycles was performed with one cycle of ℃ → room temperature. The acceleration test is 3G (200Hz,
(Sinusoidal vibration) for 720 hours.

As shown in the test results in Table 5, the ceramic structure of the present invention did not change in the natural frequency, and the reliability of the joined body according to the present invention could be confirmed.

[0065]

[Table 5]

[0066]

As described above, according to the present invention, a plurality of ceramic members are moved 9
SiO ₂ , Al ₂ O having a coefficient of thermal expansion of 0 to 97%
_{3, B 2 O 3, Bi} 2 O 3, BaO, by joined by using a bonding material composed of at least two or more of ZnO, which provides a ceramic structure with high bonding strength and reliability be able to.

[Brief description of the drawings]

1 (a) to 1 (c) are views showing a ceramic joined body of the present invention and a method for manufacturing the same.

FIGS. 2A to 2C are views showing a ceramic joined body of the present invention and a method of manufacturing the same.

FIGS. 3A to 3C are views showing a ceramic joined body of the present invention and a method of manufacturing the same.

4 (a) to 4 (c) are views showing a ceramic joined body of the present invention and a method for producing the same.

FIG. 5 is a schematic view of an exposure apparatus which is an example of a semiconductor manufacturing apparatus.

[Explanation of symbols]

 1: Structure 2: Top plate 3: Box material 4: Ceramics joined body 5: Wiring member

Claims (2)

[Claims] 1. The method according to claim 1, wherein the first and _second layers are SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ and Bi _2.
At least two or more of O ₃ , BaO, and ZnO are blended, and the plurality of ceramic members are joined to each other using a joining material having a thermal expansion coefficient of 90 to 97% of the ceramic member to be joined. A ceramic structure characterized by the following. 2. The method according to claim 1, further comprising the step of:
SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , Bi ₂ O having a thermal expansion coefficient of 90 to 97% with respect to the ceramic member
_3. A method for manufacturing a ceramic structure comprising a step of baking a bonding material composed of at least two of BaO and ZnO, reducing the surface thereof to a flatness of 50 μm or less, pressure-bonding the same, and heat-treating at 700 to 1000 ° C. Method.