JP2005066710A - Manufacturing method for vacuum chuck - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a vacuum chuck in which at least all sucking faces have high rigidity and high thermal conductivity. <P>SOLUTION: A large number of through-holes for vacuum suction are provided on a plate-like body in which at least all the sucking faces are formed of a composite body comprising metal and ceramic in the method for manufacturing the vacuum chuck. The manufacturing method is composed of (a) a process for manufacturing a ceramic molded body 7b to which a pin 9 to be eliminated by burning under an oxidizing atmosphere, (b) a process in which the ceramic molded body 7b is sintered under a non-oxidizing atmosphere and formed into an SiC sintered body 7c being a ceramic porous body having a three-dimensional network structure, (c) a process in which the SiC sintered body 7c is formed into a disk-like body 13 formed of the composite body comprising the metal and the ceramic by impregnating metal silicon into the SiC sintered body 7c, and (d) a process in which the disk-like body 13 is formed into a shape with the through-hole 6 for the vacuum suction by eliminating the pin 9 by burning the disk-like body 13 under the oxidizing atmosphere. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

表１に示したように、各実施例により製造した真空チャック２はヤング率が２５０ＧＰａ以上で、熱伝導率が１５０Ｗ／ｍ・Ｋ以上であり、両方の性質を満たしている。そして、その真空チャック２を用いて半導体ウエハを研磨した結果、各比較例の真空チャックを用いた場合よりウエハ平坦度に優れていることがわかった。
【００５７】
尚、前記実施形態及び実施例を次のように変更して構成することも可能である。
・ 前記実施形態及び各実施例では、真空チャック２全体を金属とセラミックの複合体で形成したが、例えば金属の含浸時に、含浸する金属を半導体ウエハの吸着面の大きさの仕切板で囲い、その内側のみに金属を含浸させるようにしてもよい。これにより、半導体ウエハの吸着面のみを金属とセラミックの複合体とし、その他の部分を別の素材で形成することができる。
【００５８】
・ セラミック多孔質体に含浸させる金属の形態は、円柱体等の粒状体、或いは粉末等であってもよい。
・ セラミックとして、アルミナ、炭化珪素及び窒化珪素から選ばれる２種以上を組合せて使用してもよく、金属としてシリコンとアルミニウムを組合せて使用してもよい。
【００５９】
・前記貫通孔６を形成するためのピンとして、焼いて消失させることの可能なピンであれば良く、黒鉛等も使用可能である。
更に、前記実施形態及び実施例から把握できる請求項以外の技術的思想について、その効果と共に記載する。
【００６０】
・前記貫通孔は直径０．５ｍｍ以下の円孔である請求項１から請求項３のいずれか一項に記載の真空チャックの製造方法。
この製造方法によれば、吸着時における貫通孔の形状の半導体ウエハへの転写、或いは貫通孔の空間が大きいことによる半導体ウエハの撓みを防止できる。
【００６１】
・少なくとも吸着面の全てが金属とセラミックの複合体で形成された板状体に真空吸着用の貫通孔を複数形成した真空チャックの製造方法であって、以下の製造工程よりなることを特徴とする真空チャックの製造方法。
ａ）酸化雰囲気下にて焼いて消失させることの可能なピンを内部に複数配設し、その端部が外部へ突出するように構成し、金属粒子及びセラミック粒子からなる複合成形体を製造する工程。
ｂ）前記複合成形体を非酸化雰囲気下にて焼結して金属とセラミックの複合体で形成された板状体とする工程。
ｃ）前記金属とセラミックの複合体で形成された板状体を酸化雰囲気下で焼いて、ピンを消失させ、真空吸着用の貫通孔とする工程。
【００６２】
この製造方法によれば、製造工程を簡略化することができる。
・前記含浸させる金属は、金属の破砕体がセラミック多孔質体上にセラミック多孔質体を覆うように多数配置されるものである請求項１から請求項３のいずれか一項に記載の真空チャックの製造方法。
【００６３】
この製造方法によれば、含浸させる金属をセラミック多孔質体に十分に接触させることができ、効率よく含浸させることができる。
【００６４】
【発明の効果】
請求項１に記載の発明の真空チャックの製造方法によれば、少なくとも吸着面の全てが高剛性かつ高熱伝導率である真空チャックを効率良く製造することができる。
【００６５】
請求項２に記載の発明の真空チャックの製造方法によれば、請求項１に記載の発明の効果に加え、真空チャックの剛性を向上させることができる。
請求項３に記載の発明の真空チャックの製造方法によれば、請求項１又は請求項２に記載の発明の効果に加え、真空チャックの熱伝導率を向上させることができる。
【図面の簡単な説明】
【図１】本発明の実施形態における真空チャックを用いる半導体ウエハ研磨装置を模式的に示す正面図。
【図２】実施形態の真空チャックを拡大して示す平面図。
【図３】図２のＡ−Ａ線における断面図。
【図４】（ａ）〜（ｆ）は真空チャックの製造工程を示す断面図。
【符号の説明】
２…真空チャック、２ａ…吸着面、６…真空吸着用の貫通孔、７ｂ…セラミック成形体、７ｃ…セラミック多孔質体としてのＳｉＣ焼結体、１３…板状体としての円板状体。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a vacuum chuck for adsorbing a semiconductor wafer when, for example, the surface of the semiconductor wafer is polished.
[0002]
[Prior art]
Conventionally, in order to polish a semiconductor wafer, a vacuum chuck that sucks and polishes the semiconductor wafer is used. That is, the semiconductor wafer is adsorbed by a vacuum chuck, placed on a surface plate, and the semiconductor wafer is polished with desired accuracy by rotating both the surface plate and the vacuum chuck. The portion of the vacuum chuck that adsorbs the semiconductor wafer is composed of a metal plate such as aluminum or stainless steel having a large number of through holes, or a ceramic plate such as aluminum oxide or silicon carbide (for example, Patent Document 1, Patent). Reference 2). This through hole needs to have a diameter of 0.5 mm or less. In the case of a through hole having a diameter larger than 0.5 mm, the shape of the hole may be transferred to the semiconductor wafer at the time of adsorption, or the semiconductor wafer may be bent due to the large space of the through hole. Then, the semiconductor wafer is strongly adsorbed by vacuum through the through holes of these metal plates and ceramic plates, and high-precision polishing is performed in this state.
[0003]
However, in recent years, there has been a demand from the market for increasing the size of semiconductor wafers and increasing the precision of polishing. As a result, there was no problem with conventional semiconductor wafers, but with large semiconductor wafers, the size of the vacuum chuck increases, so when the semiconductor wafer is attracted by the vacuum chuck, the deflection of the vacuum chuck increases. The degree of vacuum decreases. For this reason, it is a cause that the polishing accuracy is lowered by lowering the suction force of the vacuum chuck. Therefore, a highly rigid material is required as a material for the vacuum chuck.
[0004]
As another problem, in a large semiconductor wafer, the degree of vacuum is lowered due to deformation of the vacuum chuck due to frictional heat generated during polishing, and this causes a reduction in polishing accuracy due to a decrease in adsorption force. . In addition, the frictional heat causes the semiconductor wafer and the vacuum chuck to be thermally deformed, causing a reduction in polishing accuracy. For this reason, a material having high thermal conductivity is required as a material for the vacuum chuck.
[0005]
Therefore, the applicant of the present application has proposed a vacuum chuck obtained by studying to realize high rigidity and high thermal conductivity as a material of the vacuum chuck. That is, in order to realize high rigidity and high thermal conductivity as a material of such a vacuum chuck, a composite body in which the adsorption surface of the semiconductor wafer is composed of a ceramic porous body and the other portions are impregnated with a metal in the ceramic porous body It is composed of And the adsorption | suction hole penetrated by the drilling process etc. in the ceramic porous body in an adsorption | suction surface is provided (for example, refer patent document 3).
[0006]
[Patent Document 1]
Japanese Unexamined Patent Publication No. 11-320394 (page 9, FIG. 1, FIG. 2)
[Patent Document 2]
JP 2000-271862 A (page 3-5)
[Patent Document 3]
JP 2002-36102 A (page 8, FIGS. 1 and 2)
[0007]
[Problems to be solved by the invention]
However, the prior art has the following problems.
The semiconductor wafer adsorption surface of the vacuum chuck is a ceramic porous body obtained by, for example, impregnating metal silicon into a ceramic fired body obtained by firing silicon carbide and then etching the portion that becomes the semiconductor wafer adsorption surface to make it porous. It is configured. For this reason, the rigidity of the semiconductor wafer adsorption surface is low and the thermal conductivity is low, and the high rigidity and high thermal conductivity required for the material of the vacuum chuck cannot be satisfied. In addition, there is a problem that it is complicated because a post-process for forming the suction holes is necessary.
[0008]
The present invention has been made in view of the above problems of the prior art. An object of the present invention is to provide a method of manufacturing a vacuum chuck capable of efficiently manufacturing a vacuum chuck having at least all of the adsorption surfaces having high rigidity and high thermal conductivity.
[0009]
[Means for Solving the Problems]
The method of manufacturing a vacuum chuck according to the first aspect of the present invention is a method of manufacturing a vacuum chuck in which a plurality of through-holes for vacuum suction are formed in a plate-like body having at least all of the suction surfaces formed of a composite of metal and ceramic. And, it consists of the following manufacturing processes.
a) A step of manufacturing a ceramic molded body in which a plurality of pins that can be burned and disappeared in an oxidizing atmosphere are disposed inside, and end portions thereof protrude outward.
b) A step of sintering the molded body in a non-oxidizing atmosphere to form a ceramic porous body having a three-dimensional network structure.
c) A step of impregnating the ceramic porous body with metal to form a plate-like body formed of a composite of metal and ceramic.
d) A step of baking the plate-like body formed of the metal-ceramic composite body in an oxidizing atmosphere to eliminate the pins, thereby forming through holes for vacuum adsorption.
[0010]
In the first aspect of the present invention, by using a plate-like body made of a composite material in which a metal having a high thermal conductivity and a ceramic having a high rigidity are used in a vacuum chuck, a vacuum having at least an adsorption surface having a high rigidity and a high thermal conductivity. A chuck can be manufactured. In that case, the through holes can be formed at the same time, and the vacuum chuck can be manufactured efficiently.
[0011]
According to a second aspect of the present invention, there is provided a vacuum chuck manufacturing method according to the first aspect, wherein the ceramic is alumina, silicon carbide, or silicon nitride. In the invention described in claim 2, a vacuum chuck with higher rigidity can be manufactured by using alumina, silicon carbide or silicon nitride as the ceramic.
[0012]
According to a third aspect of the present invention, there is provided a vacuum chuck manufacturing method according to the first or second aspect, wherein the metal is silicon or aluminum. In the invention according to claim 3, a vacuum chuck having higher thermal conductivity can be manufactured by using silicon or aluminum as the metal.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the method for manufacturing a vacuum chuck of the present invention will be described in detail.
FIG. 1 is a diagram schematically showing an example of a semiconductor wafer polishing apparatus using the vacuum chuck of the present embodiment. As shown in FIG. 1, a semiconductor wafer polishing apparatus 1 includes a vacuum chuck 2 that holds a semiconductor wafer 3 by suction and a disk-shaped surface plate 5 having a polishing surface 5a. Then, after the semiconductor wafer 3 is brought into contact with the polishing surface 5a of the surface plate 5 with the vacuum chuck 2 adsorbing and holding the semiconductor wafer 3, the surface of the semiconductor wafer 3 is rotated by rotating the vacuum chuck 2 and the surface plate 5. Is supposed to be polished.
[0014]
The vacuum chuck 2 is a disk-like body 13 as a plate-like body made of a composite (hereinafter also referred to as a SiC / Si composite) in which silicon carbide (SiC) as a ceramic is impregnated with silicon (Si) as a metal. It has. The SiC / Si composite has a three-dimensional network structure formed by firing. The lower surface of the disk-shaped body 13 is an adsorption surface 2a, and the entire adsorption surface 2a is formed of a SiC / Si composite.
[0015]
A large number of through-holes 6 for vacuum suction are formed in the disk-like body 13. The diameter of the through hole 6 is 0.5 mm, and the total hole area is about 1% of the area of the adsorption surface 2a. The through hole 6 preferably has a diameter of 0.5 mm or less. In the case of the through-hole 6 having a diameter larger than 0.5 mm, the shape of the hole at the time of adsorption is transferred to the semiconductor wafer 3 or the semiconductor wafer 3 is bent due to the large space of the through-hole 6. And through this through-hole 6, the semiconductor wafer 3 is strongly adsorbed by a vacuum suction force, and high-precision polishing is performed in this state. The vacuum chuck 2 is configured by providing a through-hole 6 in a disk-like body 13.
[0016]
The vacuum chuck 2 is disposed above the surface plate 5 with the suction surface 2a of the disk-like body 13 that sucks and holds the semiconductor wafer 3 facing downward, and is not suctioned on the opposite side of the suction surface 2a. A columnar pusher 4 is suspended from the center of the surface 2b. The pusher 4 is connected to a driving means (not shown), and when the driving means is driven, the vacuum chuck 2 is rotated via the pusher 4. The pusher 4 supports the vacuum chuck 2 horizontally, so that the suction surface 2 a of the vacuum chuck 2 is set to be parallel to the polishing surface 5 a of the surface plate 5.
[0017]
The driving means can move the vacuum chuck 2 up and down. After the semiconductor wafer 3 held by the vacuum chuck 2 is lowered to a predetermined position on the surface plate 5, the driving means is operated at a predetermined pressure. It can be brought into pressure contact with the polishing surface 5 a of the surface plate 5.
[0018]
A polishing cloth (not shown) is affixed to the polishing surface 5a of the surface plate 5, and a cylindrical rotation shaft (not shown) is suspended from the center of the surface of the surface plate 5 opposite to the polishing surface 5a. When the rotary shaft is driven to rotate, the surface plate 5 rotates. Further, a flow path (not shown) is formed inside the surface plate 5, and the temperature of the surface plate 5 can be controlled by circulating a coolant such as cooling water through the flow path.
[0019]
When polishing the semiconductor wafer 3, first, the vacuum chuck 2 on which the semiconductor wafer 3 is adsorbed on the adsorption surface 2 a of the disk-like body 13 and the surface plate 5 are rotated. Next, the surface to be polished 3a of the semiconductor wafer 3 is polished by moving the vacuum chuck 2 or the surface plate 5 upward or downward to bring the semiconductor wafer 3 into sliding contact with the polishing cloth.
[0020]
Here, the vacuum chuck 2 is required to have high rigidity and high thermal conductivity, and the rigidity is preferably a Young's modulus of 250 GPa or more. If the Young's modulus is less than 250 GPa, it may cause the vacuum chuck 2 to bend, and high-precision polishing may not be possible. In addition, the upper limit of Young's modulus is about 500 GPa from the viewpoint of material availability, cost, and the like. Further, the thermal conductivity is preferably 150 W / m · K or more. If the thermal conductivity is less than 150 W / m · K, the vacuum chuck 2 may be deformed by frictional heat, and high-precision polishing may not be possible. In addition, the upper limit of thermal conductivity is about 300 W / m · K from the viewpoints of availability of materials, cost, and the like. The vacuum chuck 2 is required to satisfy the above two properties at the same time.
[0021]
2 is an enlarged plan view showing the vacuum chuck 2 of the present embodiment, and FIG. 3 is a cross-sectional view taken along the line AA of FIG. The vacuum chuck 2 of this embodiment is formed of a SiC / Si composite in which a silicon carbide (SiC) porous body is impregnated with metal silicon (Si).
[0022]
Next, the manufacturing method of the vacuum chuck 2 is demonstrated based on FIG.
A polyethylene pot in a ball mill is mixed with 1.5 parts by mass of a 1-inch diameter fluororesin ball, 17 parts by mass of ion-exchanged water, 1 part by mass of a dispersant, and 2 parts by mass of a pH adjuster. Further, 100 parts by mass of SiC powder is added and mixed in a ball mill for 20 hours to prepare a raw material slurry.
[0023]
As shown in FIG. 4A, the obtained raw material slurry 7a is poured into a substantially bottomed cylindrical die 8. As shown in FIG. 4B, a carbon pin 9 in which artificial graphite is processed to a diameter of 0.5 mm is inserted as a pin that can be burned and disappeared in an oxidizing atmosphere. Then, the temperature is raised stepwise in the order of 30 ° C. for 12 hours, 50 ° C. for 12 hours, 70 ° C. for 12 hours, and 100 ° C. for 20 hours to obtain a ceramic molded body 7b.
[0024]
Next, as shown in FIG. 4C, the compact is put in a carbon crucible 10 and fired at 2000 ° C. for 2 hours in a non-oxidizing atmosphere furnace such as an argon (Ar) atmosphere furnace, and ceramic. A SiC sintered body 7c as a porous body was obtained. Here, an Ar atmosphere furnace is used as a non-oxidizing atmosphere furnace, but the non-oxidizing atmosphere furnace is not limited to an Ar atmosphere furnace, and a vacuum atmosphere furnace or the like can also be used. Further, the temperature and firing time of the non-oxidizing atmosphere furnace are not limited to 2000 ° C. and 2 hours, and may be performed under conditions suitable for obtaining a ceramic sintered body. It is not intended to limit the invention.
[0025]
Further, as shown in FIG. 4D, after processing the SiC sintered body 7c into a disc shape, a large number of crushed metal silicon bodies 11 are placed on the SiC sintered body 7c, and a 1500 atmosphere in a vacuum atmosphere furnace. By heating at ° C for 6 hours, the crushed body 11 is melted and impregnated in the SiC sintered body 7c. In this way, a disk-like body 13 impregnated with silicon is obtained.
[0026]
Next, as shown in FIG. 4 (e), the disk-like body 13 is taken out of the crucible 10 and placed on the support base 14 in the oxidizing atmosphere furnace 12, heated at 800 ° C. for 48 hours, and inserted in advance. The carbon pin 9 is burned and disappears. Then, the space in which the carbon pin 9 was present is formed so as to be a through-hole 6 for vacuum adsorption, and the vacuum chuck 2 made of the SiC / Si composite disk-shaped body 13 shown in FIG. obtain.
[0027]
Now, when the surface of the semiconductor wafer 3 is polished, a vacuum suction force is applied from the through hole 6 of the disk-like body 13 to attract the semiconductor wafer 3 to the suction surface 2a. Next, after the vacuum chuck 2 is brought into contact with the polishing surface 5a of the surface plate 5 with the semiconductor wafer 3 being sucked and held, the surface of the semiconductor wafer 3 is polished by rotating the vacuum chuck 2 and the surface plate 5.
[0028]
At this time, the disk-like body 13 of the vacuum chuck 2 has a structure in which silicon is impregnated into the voids of the three-dimensional network structure of baked silicon carbide, and has a Young's modulus of 320 GPa and a thermal conductivity of 200 W / It is about m · K and has high rigidity and high thermal conductivity. For this reason, while the shape of the disk-shaped body 13 is hold | maintained favorably, heat dissipation performance is also favorable. Accordingly, the vacuum chuck 2 is prevented from being deformed by frictional heat generated by the bending or polishing of the disk-like body 13 itself, and the flatness thereof is ensured. As a result, the semiconductor wafer 3 can be polished with high accuracy without causing minute waviness or the like.
[0029]
According to this embodiment, the following effects can be achieved.
-According to the manufacturing method of the vacuum chuck of the present embodiment, the vacuum chuck 2 in which the through-hole 6 for adsorption is provided on the composite of metal and ceramic is efficiently manufactured without requiring a drilling process in a subsequent process. can do. The obtained vacuum chuck 2 has high rigidity and high thermal conductivity, suppresses deformation due to bending and frictional heat, avoids a decrease in adsorption force, and can polish a large semiconductor wafer with high accuracy.
[0030]
-Since the three-dimensional network structure of the SiC sintered body 7c as the ceramic porous body is impregnated with silicon as the metal, the high rigidity and high thermal conductivity, which are the advantages of each of the ceramic and the metal, are further improved. Both can be achieved at a high level.
[0031]
-Rigidity can be improved by using alumina, silicon carbide, or silicon nitride as ceramic.
-Thermal conductivity can be improved by using silicon or aluminum as a metal.
[0032]
【Example】
(Example 1)
In Example 1, a SiC / Si composite vacuum chuck in which a silicon carbide (SiC) porous body was impregnated with metallic silicon (Si) was produced according to the process shown in FIG.
[0033]
1.5 parts by mass of a fluorine resin ball having a diameter of 1 inch, 17 parts by mass of ion-exchanged water, and 1 part by mass of a styrene-maleic acid copolymer (SMA1440H made by ATOFINA Chemical) as a dispersant in a polyethylene pot in a ball mill, And 2 parts by mass of 2,2 ′, 2 ″ -nitrilotriethanol (manufactured by Kanto Chemical Co., Ltd.) as a pH adjuster were further mixed. 100% by weight of Ultrafine (Ibiden Co., Ltd.), which is SiC powder having an average particle size of 0.5 μm, is added to 100 parts by weight of a mixture and mixed in a ball mill for 20 hours. A slurry was prepared.
[0034]
The obtained raw material slurry was poured into a mold 8, and a carbon pin 9 obtained by processing artificial graphite (ET-10 manufactured by Ibiden Co., Ltd.) to a diameter of 0.5 mm was inserted therein. It was heated stepwise in the order of 30 ° C. for 12 hours, 50 ° C. for 12 hours, 70 ° C. for 12 hours, and 100 ° C. for 20 hours, and dried to obtain a ceramic molded body 7b.
[0035]
Next, the compact is put in a carbon crucible 10 and baked at 2000 ° C. for 2 hours in an argon (Ar) atmosphere furnace, and a SiC sintered body 7c which is a ceramic porous body having a three-dimensional network structure. Got. Furthermore, after processing it into a disk shape, the silicon crushed body 11 and the SiC sintered body 7c are brought into contact with each other, and the silicon crushed body 11 is melted in a vacuum atmosphere furnace at 1500 ° C. for 6 hours to obtain an SiC sintered body. By impregnating 7c, a disk-like body 13 made of a SiC / Si composite was obtained.
[0036]
Next, the disk-like body 13 is heated in an oxidizing atmosphere furnace at 800 ° C. for 48 hours, and the carbon pin 9 previously inserted is baked to disappear, and the space where the carbon pin 9 was present is vacuum adsorbed. A vacuum chuck 2 made of a disc-like body 13 of SiC / Si composite was obtained.
[0037]
The vacuum chuck 2 thus obtained had a Young's modulus of 320 GPa and a thermal conductivity of 200 W / m · K.
(Example 2)
In Example 2, a vacuum chuck 2 of a SiC / Al composite disk-like body 13 in which an SiC porous body was impregnated with aluminum (Al) was produced.
[0038]
This production is the same as that in Example 1 from the production of the raw slurry to the processing of the SiC sintered body 7c, which is a ceramic porous body having a three-dimensional network structure, into a disk shape. In the impregnation with Al, the SiC sintered body 7c was immersed in molten Al and impregnated with Al.
[0039]
Next, the carbon pin 9 was burned and disappeared in the same manner as in Example 1, and the space in which the carbon pin 9 existed was formed to be the through-hole 6 for vacuum adsorption, and the SiC / Al composite disc A vacuum chuck 2 composed of the body 13 was obtained.
[0040]
The vacuum chuck 2 thus obtained had a Young's modulus of 280 GPa and a thermal conductivity of 240 W / m · K. (Example 3)
In Example 3, an SiC / Si composite vacuum chuck 2 was manufactured by composite sintering of SiC particles and Si particles.
[0041]
That is, GP # 240 (manufactured by Shinano Denki Smelting Co., Ltd.), which is an SiC powder having an average particle size of 57 μm, is 70 wt%, and Ultra Fine (manufactured by Ibiden Co., Ltd.), which is an SiC powder having an average particle size of 0.5 μm 100 parts by mass of a 30% by weight mixture, 35 parts by mass of Si powder (average particle size 5 μm), and 5 parts by mass of phenol resin BRL204 (manufactured by Showa Polymer Co., Ltd.) were dry mixed to obtain granules.
[0042]
Thereafter, the insertion of the carbon pin and the steps after the molding were carried out in the same manner as in Example 1 to produce a vacuum chuck 2 of SiC / Si composite by composite sintering of SiC particles and Si particles.
[0043]
The vacuum chuck 2 thus obtained had a Young's modulus of 300 GPa and a thermal conductivity of 190 W / m · K.
In Example 3, the process could be simplified while ensuring high rigidity by ceramic and high thermal conductivity by metal.
(Comparative Example 1)
In Comparative Example 1, an alumina sintered compact vacuum chuck was produced.
[0044]
Alumina granules of A96 were temporarily formed with a carbon mold and formed into a compact with a hydraulic press (130 MPa), and then cut into a predetermined shape and provided with a through-hole for vacuum adsorption.
[0045]
Next, the cut compact was sintered in an atmospheric furnace (oxidizing atmosphere furnace) to produce a vacuum chuck of an alumina sintered body. The temperature at that time is from room temperature to 2 ° C./min. The temperature was increased to 500 ° C. at a temperature increase rate of 500 ° C., and after 1 hour at 500 ° C., 500 ° C. to 5 ° C./min. The temperature is increased to 1500 ° C. at a temperature increase rate of 1 hour at 1500 ° C.
[0046]
The vacuum chuck thus obtained had a Young's modulus of 350 GPa and a thermal conductivity of 30 W / m · K.
(Comparative Example 2)
In Comparative Example 2, a stainless steel vacuum chuck was produced.
[0047]
A SUS304 material was processed into a predetermined shape to form through holes for vacuum suction, and a stainless steel vacuum chuck was produced.
The vacuum chuck thus obtained had a Young's modulus of 200 GPa and a thermal conductivity of 20 W / m · K.
(Comparative Example 3)
In Comparative Example 3, an SiC dense vacuum chuck was produced.
[0048]
100 parts by mass of Ultrafine (produced by Ibiden Co., Ltd.), 3 parts by mass of phenol resin BRL204 (produced by Showa Polymer Co., Ltd.), 0.64 parts by mass of boron carbide produced by Stark Co., and 140 parts by mass of methanol Were mixed to prepare a raw material slurry. The raw material slurry was dried at 80 ° C. with a spray dryer to form granules.
[0049]
Next, after temporary molding at a molding pressure of 10 MPa using a uniaxial press machine and a carbon mold, it was molded at a pressure of 130 MPa using a hydraulic press machine. Subsequently, after processing this into a predetermined shape and providing a through-hole for vacuum adsorption, baking was performed at 2100 ° C. for 5 hours in an Ar atmosphere furnace to manufacture a vacuum chuck of a SiC dense body.
[0050]
The vacuum chuck thus obtained had a Young's modulus of 400 GPa and a thermal conductivity of 90 W / m · K.
(Comparative Example 4)
100 parts by mass of α-type silicon carbide powder (# 400) having an average particle size of 30 μm and 30 parts by mass of α-type silicon carbide powder (GMF-15H2) having an average particle size of 0.3 μm were uniformly mixed. Next, after blending 5 parts by mass of polyvinyl alcohol, 3 parts by mass of phenol resin, and 50 parts by mass of water with respect to 100 parts by mass of this mixture, a uniform mixture was obtained by mixing in a ball mill for 5 hours. The mixture was dried for a predetermined time to remove water to some extent, and then an appropriate amount of the dried mixture was collected and granulated using a spray drying method or the like. At this time, the moisture content of the granules was adjusted to about 0.8% by mass.
[0051]
Subsequently, the granule of the said mixture was shape | molded by the press pressure of 125 MPa using the metal stamping die. The density of the resulting disc-shaped product (diameter 200 mm, thickness 25 mm) is 2.6 g / cm. ³ Met. Subsequently, the generated shape is inserted into a graphite crucible, and the generated shape is held in a 1 atmosphere argon atmosphere at 10 ° C./min and 2200 ° C. for 4 hours using a Tamman-type baking furnace. The disc-shaped body made of a porous ceramic having a diameter of 200 mm and a thickness of 25 mm was obtained by performing the above baking. The porosity of this porous ceramic was 20%.
[0052]
Next, the obtained disc-shaped body was impregnated with a phenol resin (carbonization rate: 30% by mass) in advance and dried. Thereafter, a slurry containing metallic silicon was coated on the surface of the disk-shaped body. Here, as the slurry, a mixture of 100 parts by mass of metal silicon powder having an average particle diameter of 20 μm and a purity of 99.9999% by mass or more and 60 parts by mass of a 5% by mass acrylic ester-benzene solution is used. It was. Then, the disk-like body coated with metal silicon was heated in an argon gas stream at a heating rate of 450 ° C./hour and held at a maximum temperature of 1450 ° C. for about 1 hour. By such treatment, metal silicon was infiltrated into the disk-like body to obtain a metal-porous silicon carbide composite. The impregnation amount of metal silicon with respect to 100 parts by mass of silicon carbide was 30 parts by mass.
[0053]
The obtained metal-porous silicon carbide composite had a thermal conductivity of 210 W / m · K and a density of 3.0 g / cm. ³ Met. The average particle size of the porous silicon carbide crystal was 30 μm, and specifically, 20% by volume of fine crystals having an average particle size of 1.0 μm and 80% by volume of crude crystals having an average particle size of 40 μm were included. Subsequently, an etching resist made of an epoxy resin was formed on the outer peripheral portion and the side surface of one main surface of the metal-porous silicon carbide composite. At this time, the diameter of the etching resist non-formation part of a metal-porous silicon carbide composite was 180 mm.
[0054]
Then, the metal-porous silicon carbide composite is immersed in an etching solution composed of hydrogen fluoride: nitric acid: water = 1: 1: 1 (volume ratio), pulled up after 180 seconds, and is applied to the one main surface. A porous silicon carbide layer having a thickness of 0.5 mm was formed. Thereafter, the etching resist was removed by heat treatment to produce a metal-porous silicon carbide composite having a porous silicon carbide layer on one main surface. Seven suction holes (diameter 5 mm) penetrating the porous silicon carbide layer from the porous silicon carbide layer non-formation surface of the obtained metal-porous silicon carbide composite were formed by drilling to produce a vacuum chuck.
[0055]
Table 1 shows the results obtained by adding the wafer flatness when polishing a semiconductor wafer having a diameter of 300 mm using the Young's modulus and thermal conductivity of each of the above Examples and Comparative Examples. The wafer flatness is a difference (distance) between the highest point and the lowest point on the polished surface by a flat surface measuring device (Nanometro manufactured by Kuroda Seiko Co., Ltd.). Moreover, the Young's modulus and thermal conductivity of Comparative Example 4 indicate the values of the porous silicon carbide layer constituting the adsorption surface.
[0056]
[Table 1]

As shown in Table 1, the vacuum chuck 2 manufactured according to each example has a Young's modulus of 250 GPa or more and a thermal conductivity of 150 W / m · K or more and satisfies both properties. As a result of polishing the semiconductor wafer using the vacuum chuck 2, it was found that the wafer flatness was superior to the case of using the vacuum chucks of the comparative examples.
[0057]
It should be noted that the above embodiment and examples can be modified as follows.
In the embodiment and each example, the entire vacuum chuck 2 is formed of a composite of metal and ceramic. For example, when impregnating the metal, the impregnated metal is surrounded by a partition plate having the size of the adsorption surface of the semiconductor wafer, Only the inside may be impregnated with metal. Thereby, only the adsorption | suction surface of a semiconductor wafer can be made into the composite of a metal and a ceramic, and another part can be formed with another raw material.
[0058]
-The form of the metal impregnated in the ceramic porous body may be a granular body such as a cylinder or a powder.
A ceramic may be used in combination of two or more selected from alumina, silicon carbide and silicon nitride, and a metal may be used in combination of silicon and aluminum.
[0059]
As a pin for forming the through hole 6, any pin that can be burned and disappeared may be used, and graphite or the like can be used.
Further, technical ideas other than the claims that can be grasped from the embodiments and examples will be described together with the effects thereof.
[0060]
The method for manufacturing a vacuum chuck according to any one of claims 1 to 3, wherein the through hole is a circular hole having a diameter of 0.5 mm or less.
According to this manufacturing method, it is possible to prevent the shape of the through hole from being transferred to the semiconductor wafer at the time of adsorption, or the bending of the semiconductor wafer due to the large space of the through hole.
[0061]
A vacuum chuck manufacturing method in which a plurality of through-holes for vacuum suction are formed in a plate-like body in which at least all of the suction surfaces are formed of a composite of metal and ceramic, and includes the following manufacturing steps A manufacturing method of a vacuum chuck.
a) A plurality of pins that can be burned and disappeared in an oxidizing atmosphere are arranged inside, and the ends thereof protrude outward, and a composite molded body made of metal particles and ceramic particles is manufactured. Process.
b) A step of sintering the composite molded body in a non-oxidizing atmosphere to form a plate-like body formed of a composite of metal and ceramic.
c) A step of baking a plate-like body formed of a composite of the metal and ceramic in an oxidizing atmosphere to eliminate the pins and form a through-hole for vacuum adsorption.
[0062]
According to this manufacturing method, the manufacturing process can be simplified.
The vacuum chuck according to any one of claims 1 to 3, wherein the metal to be impregnated is arranged in a large number so that a crushed metal body covers the ceramic porous body on the ceramic porous body. Manufacturing method.
[0063]
According to this manufacturing method, the metal to be impregnated can be sufficiently brought into contact with the ceramic porous body, and can be impregnated efficiently.
[0064]
【The invention's effect】
According to the vacuum chuck manufacturing method of the first aspect of the present invention, it is possible to efficiently manufacture a vacuum chuck in which at least all of the suction surfaces have high rigidity and high thermal conductivity.
[0065]
According to the vacuum chuck manufacturing method of the invention described in claim 2, in addition to the effect of the invention described in claim 1, the rigidity of the vacuum chuck can be improved.
According to the vacuum chuck manufacturing method of the invention described in claim 3, in addition to the effects of the invention described in claim 1 or claim 2, the thermal conductivity of the vacuum chuck can be improved.
[Brief description of the drawings]
FIG. 1 is a front view schematically showing a semiconductor wafer polishing apparatus using a vacuum chuck in an embodiment of the present invention.
FIG. 2 is an enlarged plan view showing the vacuum chuck of the embodiment.
3 is a cross-sectional view taken along line AA in FIG.
4A to 4F are cross-sectional views showing a manufacturing process of a vacuum chuck.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 2 ... Vacuum chuck, 2a ... Adsorption | suction surface, 6 ... Through-hole for vacuum adsorption, 7b ... Ceramic molded object, 7c ... SiC sintered compact as a ceramic porous body, 13 ... Disc-shaped object as a plate-shaped object.

Claims (3)

A manufacturing method of a vacuum chuck in which a plurality of through-holes for vacuum suction are formed in a plate-like body having at least all of the suction surfaces formed of a composite of metal and ceramic, and includes the following manufacturing steps Manufacturing method of vacuum chuck.
a) A step of manufacturing a ceramic molded body in which a plurality of pins that can be burned and disappeared in an oxidizing atmosphere are disposed inside, and end portions thereof protrude outward.
b) A step of sintering the ceramic molded body in a non-oxidizing atmosphere to form a ceramic porous body having a three-dimensional network structure.
c) A step of impregnating the ceramic porous body with metal to form a plate-like body formed of a composite of metal and ceramic.
d) A step of baking the plate-like body formed of the metal-ceramic composite body in an oxidizing atmosphere to eliminate the pins, thereby forming through holes for vacuum adsorption. The method for manufacturing a vacuum chuck according to claim 1, wherein the ceramic is alumina, silicon carbide, or silicon nitride. The method for manufacturing a vacuum chuck according to claim 1, wherein the metal is silicon or aluminum.

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