JP2001150351A - Electrodeposition grinding wheel for dressing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve chemical resistance by forming a perfect film on the front surface of a grinding wheel having protrusions and recesses, in an electrodeposition grinding wheel for dressing of a polisher to be used for high-precision finishing such as CMP working. SOLUTION: An inner layer 15 having a polyimide organic film having the thickness of 5 μm formed by an immersion coating method, an intermediate layer 16 having a W (tungsten) metallic film having the thickness of 1 μm formed by imbalance magnetron sputtering method, and an outer layer 17 having a solid lubricating material film having the thickness of 3 μm and made of hard carbon formed by a unbalance magnetron sputtering method are formed on the front surface of an Ni plated layer 14 of an electrodeposition grinding wheel for fixing an abrasive grain 13, and a grinding material layer 12 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodeposition grinding wheel for dressing a polisher used for precision finishing, and more particularly to an electrodeposition grinding wheel suitable for dressing a polisher used for flattening a semiconductor LSI device.

[0002]

2. Description of the Related Art Polishing performed for ultra-precision and high-quality finishing of electronic parts and optical parts is performed particularly by using semiconductor L.
In the SI device, it is an important processing technology in flattening various laminated films including material processing. In response to the increase in storage capacity of semiconductors, the processing accuracy (surface roughness, flatness) and processing quality (no quality) Defects, no distortion) and higher processing performance are required.

[0003] Polishing is performed by spraying soft abrasive grains on a polisher and pressing a workpiece.
Material removal is performed by a chemical and mechanical action between the soft abrasive and the workpiece, and recently, CMP (Chemical &
A technique called “Mechanical Polishing” has attracted attention. As the CMP processing apparatus, there are, for example, apparatuses described in JP-A-7-297195 and JP-A-9-111117.

When an LSI device wafer is polished by such a CMP processing apparatus, a polishing pad made of polyurethane having a constant elastic modulus, a fiber shape and a shape pattern is used as a polisher, and SiO polishing is used as a soft abrasive. ₂ is common, and CaCO ₃ , B
The effectiveness of aCO _{3 and the} like has also been discussed. In any case, polishing is the final step in machining.
A flatness of around 1 μm and a surface roughness R _{MAX of} 10 ° level must be achieved.

[0005] In such a polishing process, it is necessary to periodically dress the surface of the polisher in order to maintain stable processing performance, and an electrodeposition grindstone on which superabrasive grains such as diamond are electrodeposited is used. And CMP
At the same time as processing, or periodically, the polished surface deteriorated layer is ground and removed, and an appropriate surface state is obtained.

[0006]

By the way, in the CMP processing of an LSI device wafer, an abrasive having a pH in a wide range from a strong acid to a strong alkali is used depending on the material of the object to be polished. For this reason, when dressing the polisher surface, a strongly acidic or strongly alkaline abrasive remaining on the polisher surface causes the N
There is a problem in that the metal of the plating layer such as i and the base material such as Fe are eroded and eluted on the polisher surface.

Another problem is that abrasive grains such as diamond fall off due to erosion of the plating layer of the electrodeposited grindstone, and the dropped abrasive grains adhere to the polisher surface and damage the surface of the device wafer such as scratches. is there.

To solve such a problem, Japanese Patent Laid-Open No. 10-5 / 1998
No. 8306 discloses a dressing whetstone in which a diamond or ceramic coating layer is formed on the surface of an electroplated whetstone or an electroformed whetstone in which diamond abrasive grains are fixed by metal plating. Also, Japanese Patent Application Laid-Open
JP-A-118912 and JP-A-10-118914 disclose that a nitride layer or a carbide layer is formed on a metal surface of a dresser in which diamond abrasive grains are bonded to a metal by an electrodeposition method or a brazing method, or a ceramic coating film is formed. The applied dressing whetstone is described.

According to these dressing whetstones, it is possible to minimize the scratch damage of the device wafer due to the removal of the abrasive grains. However, in order to form the above-mentioned coating layer, nitride layer, and carbide layer on the grindstone surface, a technique such as ion plating or a CVD method is employed, but the grindstone surface contains diamond abrasive grains. Therefore, there is unevenness in three dimensions, and there is a microscopic irradiation shadow in ion plating or CVD, and there is a high risk of erosion from strong acid or strong alkaline abrasive from that part, and sufficient chemical resistance Not really.

The problem to be solved in the present invention is CMP.
In an electrodeposited grindstone for dressing of a polisher used for precision finishing such as machining, it is an object of the present invention to enhance chemical resistance by forming a complete film on a grindstone surface having unevenness.

[0011]

The above object can be attained by forming a multilayer film having an organic layer as the inner layer and a solid lubricant film as the outer layer on the surface of the metal plating layer of the electrodeposition grindstone.
Further, an intermediate layer made of a metal film or a metal compound film can be formed between the inner layer and the outer layer.

The electrodeposited whetstone is one in which abrasive grains such as diamond are held on a base material such as iron by a metal plating layer such as nickel. In the dressing electrodeposition whetstone of the present invention, by forming a highly chemically resistant multilayer film on the surface of the metal plating layer, even when a strongly acidic, strongly alkaline abrasive is used in CMP processing or the like,
The metal plating layer and the metal of the base material are not eroded by the abrasive, and the elution of the metal and the falling off of the abrasive grains are prevented.

Here, as the organic film as the inner layer of the multilayer film, a film having a thickness of 1 to 20 μm alone or in combination of any of silicon-based, fluorine-based, polyimide-based, and epoxy-based is used. As the material film, a film having a thickness of 0.1 to 5 μm made of hard carbon or any one or a mixture of metal compounds of Ti, TiAl, and Cr is further formed as a film formed of a metal film or a metal compound film as an intermediate layer. May be any one of W, Zr, Ta, and Si, or an alloy thereof, or a nitride, carbide, or oxide thereof having a thickness of 0.1 to 3 μm.

The organic film of the inner layer functions as a barrier film for improving chemical resistance, and is a synthetic resin film, particularly a film of silicon, fluorine, polyimide or epoxy alone or in combination. Is used. In this case, if the film thickness is less than 1 μm, film defects such as pinholes are likely to occur and the chemical resistance is reduced. 20μ thickness
If it exceeds m, cracks due to shrinkage of the film surface and peeling due to film stress are likely to occur, and the chemical resistance decreases.

The solid lubricant film of the outer layer performs additional functions such as improvement of wear resistance and slidability.
Carbon-based, Ti-based, Cr-based coatings, especially hard carbon,
Alternatively, a film made of any one or a mixture of metal compounds of Ti, TiAl and Cr is used. In this case, if the film thickness is less than 0.1 μm, the effect as a solid lubricating film material is reduced, and if the film thickness exceeds 5 μm, cracks and peeling are likely to occur on the film surface due to film stress.

The metal film or metal compound film as the intermediate layer functions to improve the adhesion between the inner layer and the outer layer, and has good adhesion to both the inner organic film and the outer solid lubricant film. W, Zr, Ta, Si alone or an alloy thereof, or a nitride, carbide,
A film made of an oxide is used. In this case, the film thickness is 0.1 μm.
If it is less than m, it is difficult to increase the adhesion between the inner layer and the outer layer. Even if the film thickness exceeds 3 μm, the adhesion does not change and the productivity is reduced. Therefore, the upper limit is set to 3 μm. If the combination of the materials of the inner layer and the outer layer provides sufficient adhesion between them, the intermediate layer need not be provided.

The inner layer is formed by immersing the grindstone after electrodeposition of the abrasive grains in a coating agent of silicon type, fluorine type, polyimide type, epoxy type or the like, or by spraying a coating agent on the grinding stone. be able to. Since the organic film is also formed on the side and back surfaces of the base material by immersion or spraying, the chemical resistance of the base material is improved. After forming the inner layer, the intermediate layer can be formed by a sputtering method, an ion plating method, an arc evaporation method, or a CVD method. Similarly, the outer layer can be formed by a sputtering method, an ion plating method, an arc evaporation method, or a CVD method. In the description of the prior art, it was pointed out that ion plating and the CVD method had microscopic irradiation shadows, and that there was a high risk of erosion from a strong acid or strong alkali abrasive from that part. However, in the electrodeposition whetstone of the present invention, since an organic film having high chemical resistance is applied as an inner layer on the surface of the metal plating layer,
Even if the intermediate layer and the outer layer are formed by ion plating or the CVD method and a microscopic irradiation shadow is present, the metal plating layer is protected by the inner layer.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a view schematically showing a plate of an electrodeposited grinding wheel for dressing (hereinafter referred to as a dresser) according to an embodiment of the present invention.
(B) is a sectional view taken along line AA of (a). FIG. 2 is an explanatory view showing a procedure for forming the abrasive layer and the coating layer of the plate of FIG.

The plate 10 of the dresser of the present embodiment
It is composed of a disk-shaped base material 11 and an abrasive layer 12 formed on one surface of the base material 11, and the diameter of the base material 11 is about 10
0 mm and a thickness of about 7 mm.

The abrasive layer 12 is composed of the abrasive grains 13 and the Ni plating layer 1.
4 and an inner layer 15 formed on the Ni plating layer 14,
It is composed of an intermediate layer 16 and an outer layer 17. Inner layer 1
Reference numeral 5 denotes a polyimide organic film having a thickness of 5 μm formed by a dip coating method. The intermediate layer 16 has a thickness of 1 μm
No. W metal film was formed by a non-equilibrium magnetron sputtering method. The outer layer 17 is a solid lubricant film of hard carbon having a thickness of 3 μm formed by a non-equilibrium magnetron sputtering method.

The plate 10 is shown in FIGS.
Are formed by the following procedure. 2A shows the base material 11 before the formation of the abrasive layer, and FIG. 2B shows a state in which a portion where the abrasive layer is not formed is coated with the insulator 21 and masked. The base material 11 is immersed in the plating bath 25 in a state of being masked, and first, the abrasive grains 13 are temporarily fixed by the Ni plating layer 14a ((c) in the figure). After this temporary fixing step, unnecessary abrasive grains are removed to obtain a predetermined abrasive grain density.

Next, the Ni plating layer 14 having a thickness corresponding to 60 to 70% of the abrasive grain size (see FIG.
Is fixed ((d) in the figure). After this,
The insulator 21 is peeled off, the wiring is removed, the base material is polished, etc., to obtain a plate semi-finished product 10a. In this embodiment, thereafter, the plate semi-finished product 10a is fixed to a jig, immersed in the liquid tank 30 containing the polyimide-based coating agent 31, pulled up from the liquid tank at a constant speed, and set.
The inner layer 15 is formed by thermosetting using a drier (FIG. 7E). Next, the semi-finished plate 10a on which the inner layer 15 is formed is supplied to the non-equilibrium magnetron sputtering device 35.
W is sputtered while rotating the holder 36 in the direction of the arrow to form the intermediate layer 16 ((f) in the figure). Subsequently, the outer layer 17 which is a hard carbon film is formed by using the same apparatus, and the plate 10 (see FIG. 1) is obtained.

FIG. 3 is a perspective view showing an example of a dresser. The plate 10 shown in FIG. 1 is mounted on a flange 41 having an outer diameter of about 100 mm, and is fixed with screws from the back to form a dresser 4.
It is set to 0. The dresser 40 is dressed by pressing the dresser 40 against a polishing pad 51 on the surface of a polisher 50 of a CMP processing apparatus as shown in FIG. In the figure, 6
Reference numeral 0 denotes a suction disk for a material to be polished such as a silicon wafer.
Reference numeral 0 denotes a polishing slurry supply device. In the case of metal CMP processing, a strongly acidic polishing slurry is used as the polishing slurry.

[Test Example] The dresser (Invention 1) of the embodiment of the present invention shown in FIGS. 1 to 3 and a Ti film having a thickness of 1 μm as a first layer and a hard carbon film having a thickness of 3 μm as a second layer A processing test was conducted using a dresser (comparative product) in which was formed and a conventional dresser without a coating film (conventional product). The processing conditions are as follows. Machine used: Takuma machine Polishing pad: Foamed polyurethane 300mm outside diameter Dresser: 100mm diameter, 7mm thick plate Dresser rotation speed: 20rpm Table rotation speed: 30rpm Processing pressure: 200N Processing time: 2 hours

FIGS. 5A and 5B are schematic diagrams showing a dresser processing test method, wherein FIG. 5A is a front view and FIG. 5B is a plan view. As shown in the figure, this is a processing test in which a polishing pad W is fixed on a rotary table T of a Takuma machine and pressed against the polishing pad W while rotating a dresser K. Here, an alumina-based polishing slurry having a pH of 2 corresponding to the strongly acidic polishing slurry used in the metal CMP processing was supplied to the polishing pad W at a rate of 1 liter / min.

FIG. 6 shows the processing test results. FIG. 6 is a graph showing the degree of the abrasive grains falling off. The number of the abrasive grains falling on the vertical axis is obtained by measuring the number of the abrasive grains falling off in three areas of 20 mm × 20 mm on the dresser surface using a microscope. As shown in the figure, the conventional product is 35 pieces / mm ² , and the comparative product is 5 pieces / m 2.
There were abrasive shedding of m ^2, inventions abrasive grains fall off is nil, which were preferable results.

Table 1 shows the results of experiments on the chemical resistance of the above-mentioned invention, comparative product and conventional product. The alkali resistance test in the table indicates the degree of discoloration of each surface after immersion in a 30% NaOH solution for 30 minutes and the acid resistance test after immersion in a 20% HCl solution for 30 minutes and the presence or absence of peeling of the coating layer. It is the result of observation.

[0028]

[Table 1]

The present invention relates to an electrodeposited whetstone for dressing, and the manufacturing method described in this specification relates to a whetstone for bonding abrasive grains by metal bond, a whetstone for bonding abrasive grains by a brazing material, and the like. Can also be applied to dressing whetstones.

[0030]

According to the present invention, the following effects can be obtained.

(1) On the surface of the metal plating layer of the electrodeposition whetstone,
By forming a multilayer film in which the inner layer is an organic film having high chemical resistance and the outer layer is a solid lubricant film, even when a strongly acidic or strongly alkaline polishing agent is used in a CMP process or the like, the metal plating layer and the mother substrate are formed. The metal of the material is not eroded by the abrasive, and the elution of the metal and the falling off of the abrasive grains are prevented.

(2) By forming an intermediate layer made of a metal film or a metal compound film between the inner layer and the outer layer, the adhesion strength between the inner layer and the outer layer can be increased, and the protection against acids and alkalis can be improved. .

[Brief description of the drawings]

FIG. 1 is a view schematically showing a plate of a dresser according to an embodiment of the present invention, wherein (a) is a plan view and (b) is a cross-sectional view taken along line AA of (a).

FIG. 2 is an explanatory view showing a procedure for forming an abrasive layer and a coating film of the plate of FIG. 1;

FIG. 3 is a perspective view showing an example of a dresser.

FIG. 4 is a perspective view showing a use state of the dresser.

FIG. 5 is a schematic view showing a processing test method of a dresser.

FIG. 6 is a diagram showing a test result of a dresser.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 plate 10 a semi-finished plate 11 base material 12 abrasive layer 13 abrasive grains 14, 14 a Ni plating layer 15 inner layer 16 intermediate layer 17 outer layer 21 insulator 25 plating bath 30 liquid tank 31 coating agent 35 non-equilibrium magnetron sputtering device 36 holder 40 Dresser 41 Flange 50 Polisher 51 Polishing pad 60 Adsorber 70 Polishing slurry supply device K Dresser T Rotary table W Polishing pad

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Keizo Takeuchi 1 at Noritake Diamond Co., Ltd. Nagoya Plant, 16-family, Jinmoricho, Tsushima City, Aichi Prefecture (72) Inventor: Naosuke Adachi 2-10 Midorioka, Toyonaka-shi, Osaka No. 18 (72) Inventor Takahiko Oe 120-5 Kitano, Oyodo-cho, Yoshino-gun, Nara Prefecture CC12 EE01 EE26 FF23

Claims (5)

[Claims] 1. An electrodeposition grinding wheel for dressing wherein a multilayer film having an organic layer as an inner layer and a solid lubricant film as an outer layer is formed on a surface of a metal plating layer of the electrodeposition grinding wheel. 2. The electrodeposited grinding wheel for dressing according to claim 1, wherein said organic film is a film having a film thickness of 1 to 20 μm, alone or in combination of any of silicon, fluorine, polyimide and epoxy. 3. The dressing according to claim 1, wherein the solid lubricant film is hard carbon or a metal compound of Ti, TiAl, or Cr alone or in a mixture having a thickness of 0.1 to 5 μm. Electroplated whetstone. 4. The dressing electrodeposition wheel according to claim 1, wherein an intermediate layer made of a metal film or a metal compound film is formed between said inner layer and said outer layer. 5. The intermediate layer is a film of any one of W, Zr, Ta, and Si alone or an alloy thereof, or a nitride, carbide, or oxide thereof having a thickness of 0.1 to 3 μm. Electrodeposited whetstone for dressing as described.