JP2002355754A - Method of manufacturing backing material for holding polished object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a backing material that can secure a flat backing face by preventing the bite of air between an attached body and the backing material. SOLUTION: This method of manufacturing the backing material for holding a polished object, having a base material 2, an elastic layer 3 laminated on the base material 2, and an adhesive resin layer 4 laminated on the elastic layer 3, includes a process of sticking a film 7 with micro unevenness with a surface roughness Ra of 0.4-4.0 μm, to the surface of the adhesive resin layer 4 before the adhesive resin layer 4 is completely hardened, and a process of separating the film 7 from the surface of the adhesive resin layer after the adhesive resin layer 4 is hardened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing method for polishing a semiconductor substrate such as silicon, gallium arsenide, indium phosphide or the like, a semiconductor wafer, various substrates, glass, an LCD, a disk, etc., and holding these objects to be polished. The present invention relates to a method for manufacturing a backing material used for storage.

[0002]

2. Description of the Related Art Conventionally, semiconductor wafers, interlayer insulating films and metal wiring of semiconductor devices, memory disks, L
When performing precision flat polishing of glass for CDs, etc., an artificial leather-like polishing cloth mounted on a rotating surface plate and a rotatable workpiece holding plate placed at an opposite position are described below. A polishing liquid containing abrasive grains is supplied between the polishing object and the object fixed by various apparatus methods, and the object and the polishing cloth are slid with each other.

For example, the following method has been used as a method for holding and fixing an object to be polished according to the prior art.

(1) An object to be polished is fixed by cooling it to a temperature lower than the softening point of the wax through a wax that has been cast and applied to a holding plate made of metal or ceramics under heating. The so-called wax mounting method.

(2) A workpiece holding plate made of metal or ceramic is machined to a diameter of 0.5 mm or more.
A so-called vacuum chuck method in which a suction port of several mm is opened, and a workpiece to be polished mounted on the surface of the holding plate is fixed by suctioning from the back and side surfaces of the holding plate with a vacuum pump.

(3) A backing material made of an artificial leather-like polymer foam material is mounted on a plate for holding an object to be polished, the backing material is wetted with water, and the pressure in which water in the foamed holes is applied through the object to be polished. A so-called no-wax mounting method in which the object to be polished is fixed to the surface of the holding plate by a combination of the negative pressure of water in the foamed pores and the surface tension of the water itself when the water is discharged outside.

[0007] However, these various methods for holding the object to be polished also have their own specific disadvantages. That is, (1)
In the wax mounting method, after completion of polishing of the object to be polished, the wax used for fixing remains on the back surface of the object to be polished, and it is necessary to perform a complicated cleaning operation to remove the contamination, which is used for fixing. Since the wax itself has a softening point, the polishing temperature cannot be raised above the softening point.If the wax contains gelled substances or foreign dust, the presence of these substances will cause the surface of the workpiece to be polished during polishing. And that the finished state of polishing is deteriorated by being transferred as dimples, and that it takes time and effort to attach and detach the dimples.

(2) In the conventional vacuum chuck method, the object to be polished bends toward the suction port near the suction port formed by machining, and the surface of the object to be polished after polishing is conversely polished. The removal is left as a projection point that was insufficient and deteriorates the finished state of polishing, and the polishing liquid is sucked into the vacuum pump piping system from the suction port through the gap between the back surface of the workpiece and the holding plate during processing. And failure of the pump or corrosion of the piping.

(3) A method of fixing a semiconductor wafer to a backing material without using wax is to attach a polishing pad on a lower surface plate, fix the backing material and the template on the lower surface of the upper surface plate, and provide the template. The semiconductor wafer is placed in the recess for holding the wafer, and the upper and lower platens are relatively rotated, and while the polishing slurry is supplied onto the polishing pad, the semiconductor wafer is pressed against the polishing pad to polish the surface of the object to be polished. Is what you do.

The backing material used here is, for example,
As shown in FIG. 8, the DMF solution layer of the urethane resin coated on the base material 12 is coagulated in water, washed in warm water, dried with hot air to form a foam layer 13, and its surface is smoothed. It was formed. In the figure, 6
Denotes a polishing object, and 14 denotes a pressure-sensitive adhesive layer adhered to the back surface of the substrate 12.

However, since the surface accuracy of the holding surface of the backing material 11 reflects the coating accuracy and the defects of the coater, the surface accuracy is lower than that of the backing material having the holding surface smoothed.
There is a defect that surface accuracy is poor and surface defects such as stripes are transferred to the object to be polished.

In addition, a smooth backed ordinary backing material has a weak adsorbing force on an object to be polished. Therefore, it is necessary to use a template to prevent the object to be polished from shifting on the surface of the backing material.

The present inventors have studied a backing material in which an adhesive resin layer made of a resin is provided on the surface of the foam layer 13. In this backing material, the resin layer has such adhesiveness that the object to be polished is not rotated, so that the object to be polished is prevented from shifting on the surface of the backing material, and the surface is relatively smooth. The surface accuracy is good, and no surface defects such as streaks are transferred to the object to be polished.

However, when the adherend is attached to the surface of the backing material, air is trapped between the adherend and the backing material, and the interface between the adherend and the backing material is bent, so that a flat backing surface cannot be obtained. There is a disadvantage that. Further, the object to be polished, such as glass, is too closely adhered to the surface of the backing material, resulting in poor handleability by a machine, and also has the disadvantage that the adherend is difficult to peel off from the backing material.

[0015]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks, and an object of the present invention is to eliminate the transfer of surface defects of a backing material to an object to be polished. An object of the present invention is to provide a method of manufacturing a backing material that can improve the surface accuracy of a polished object.

Another object of the present invention is to provide a method of manufacturing a backing material which can eliminate the use of a template by increasing the attraction force to an object to be polished.

Still another object of the present invention is to provide a method of manufacturing a backing material capable of preventing air from being trapped between an adherend and a backing material so as to obtain a flat backing surface. .

Still another object of the present invention is to provide a method in which an object to be polished such as glass is not excessively adhered to the surface of the backing material, the handleability by the machine is good, and the releasability of the object from the surface of the backing material. It is another object of the present invention to provide a method of manufacturing a backing material which is appropriate.

[0019]

A method of manufacturing a backing material for holding an object to be polished according to the present invention comprises a substrate, an elastic layer laminated on the substrate, and an elastic layer laminated on the elastic layer. A method of manufacturing a backing material for holding an object to be polished having a surface roughness Ra on the surface of the resin layer before the adhesive resin layer is completely cured. Is 0.
Affixing a film having fine irregularities of 4 to 4.0 μm, and a step of peeling the film from the surface of the adhesive resin layer after the adhesive resin layer is cured,
Thereby, the above object is achieved.

In one embodiment, the method includes a step of buffing the surface of the elastic layer laminated on the surface of the base material to have a constant surface roughness.

In one embodiment, the elastic layer is made of a polyurethane resin, and has a compression ratio of 5 to 60%;
The adhesive resin layer is made of a thermosetting resin or a thermoplastic resin, has a hardness of 48 to 88 (JIS A hardness), and has a compression ratio of 3 to 52%.

The operation of the present invention is as follows.

The conventional backing material surface has poor thickness accuracy, reflecting the manufacturing process and coating accuracy. And
In many cases, the surface defect of the holding surface of the backing material is transferred to the object to be polished.

Therefore, in the present invention, the surface of the adhesive resin layer of the backing material is smoothed, and then a thermoplastic resin or a thermosetting resin is laminated on the holding surface to form a resin layer. Since this resin layer has such an adhesive property that the object to be polished is not rotated, it is possible to prevent the slurry from sneaking to the back side of the object to be polished and to decrease the holding force, and to damage the object to be polished. Can be prevented.

Further, by providing fine irregularities having a surface roughness Ra of 0.4 to 4.0 μm on the surface of the adhesive resin layer of the backing material of the present invention, it is possible to control the degree of adsorption to the object to be polished. In addition, when the object to be polished is adhered to the backing material, the air can escape to the outside through the unevenness, and the air bite generated between the object to be polished and the adhesive resin layer can be prevented.

According to the manufacturing method of the present invention, the surface roughness Ra
Can be transferred to the surface of the resin layer by attaching a film having fine irregularities of 0.4 to 4.0 μm to the surface of the resin layer and peeling the film after the resin layer is cured, so that the production is simple. In addition, uniform and fine irregularities can be formed on the backing material surface.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

As shown in FIGS. 1 to 3, the backing material 1 obtained by the manufacturing method of the present invention comprises a base material 2, an elastic layer 3 having elasticity laminated on the base material 2, It has an adhesive resin layer 4 laminated on the layer 3 and, if necessary, a pressure-sensitive adhesive layer 5 laminated on the back surface of the substrate 2. Until used, a release sheet is further releasably attached to the back surface of the pressure-sensitive adhesive layer 5.

As the substrate 2, a polyester sheet, a polyvinyl chloride sheet, a nylon sheet, a polyimide sheet or the like can be used.

As the elastic layer 3, a layer which forms a foamed layer of the backing material 1 can be used conventionally. For example, a base material 2 is coated with a DMF solution of a urethane resin, and the layer is wet-solidified. It can be formed by washing in hot water and drying with hot air. The surface of the elastic layer 3 is smoothed, and a large number of independently foamed holes are formed on the surface of the elastic layer 3. The compression ratio of the elastic layer 3 is 5 to 60%.
(Measured by JIS L1096) is preferred.

The adhesive resin layer 4 laminated on the surface of the elastic layer 3 is made of a thermosetting resin or a thermoplastic resin such as acrylic resin, polyurethane, polyester, epoxy resin, nylon, or polyvinyl chloride, and has a smooth surface. And has adhesiveness to the object to be polished. The hardness of the resin layer 4 is preferably 48 to 88 (JIS-A, J
ISK6301 (measured by 5.2 (A type)), and the compression ratio is preferably 3 to 52%.

The surface of the adhesive resin layer 4 has a surface roughness R
The fine irregularities having a of 0.4 to 4.0 μm are formed over the entire surface. These minute irregularities are formed randomly (without directionality) on the surface of the adhesive resin layer 4. A more preferable range of the surface roughness Ra is 0.5 to 2.0 (U
70-DM42) μm. Ra of minute irregularities is 0.
If it is less than 4 μm, the air escape speed is low and air may bite between the adherend and the backing material, and the handling property by the machine is poor. If it exceeds 4.0 μm, the surface accuracy is reduced. .

The backing material 1 can be manufactured, for example, as follows.

The surface of the elastic layer 3 laminated on the surface of the substrate 2 is buffed to have a constant surface roughness (irregularity), and then the surface of the elastic layer 3 is coated with a thermosetting urethane resin. Next, before this resin 4 is completely cured (the reaction is completed), as shown in FIG. 3, a film 7 having fine irregularities is pressure-bonded and laminated by a hot roll, and the surface of the backing material 1 is After bonding the urethane resin layer 4, the film is peeled off from the surface of the resin layer 4. Then, the surface roughness of the film itself is transferred to the surface of the resin layer 4 of the backing material 1, and the self-adsorption type backing material 1 having a certain roughness is obtained on the surface non-foamed urethane layer.

By producing the backing material 1 by such a manufacturing method, the surface roughness of the resin layer 4 of the backing material 1 can be controlled by controlling the surface roughness of the film 7.

In order to polish an object to be polished such as a semiconductor wafer using the backing material 1, water is adsorbed to the lower surface of the resin layer 4 of the backing material 1 with the surface to be polished facing down. Lower the holding device in the holding state, press the polishing pad surface on the lower platen with a predetermined pressure to rotate the platen, supply the slurry from the nozzle, and rotate the holding plate holding the object to be polished. Polish the polishing surface of the object to be polished.

The backing material 1 has an adhesive resin layer 4 formed on its surface, thereby holding an object to be polished such as a semiconductor wafer in an adhesive state, preventing lateral displacement during polishing, and a back surface of the object to be polished. It is possible to prevent the polishing slurry and the like from flowing around.

Further, since the elastic layer 3 is formed on the back surface of the self-adhesive resin layer 4, even if polishing dusts and the like are interposed between the object to be polished and the resin layer 4, the portion is deformed. This can prevent the object to be polished from being damaged.

[0039]

EXAMPLES First, the method of measuring the attraction force used in this example will be described below. 1. Adsorption force measurement method Adsorption force was measured 5 times and 20 times continuously in a dry or wet state in the vertical and horizontal directions. 1.1 Vertical direction As shown in FIG. 4, a cylindrical glass (50 m
m diameter) 20 is suspended by a Kepler wire 21,
The glass 20 is adsorbed by applying a load to the backing material 1 (diameter: 75 mm) fixed to the substrate. Pressing conditions were as follows. Surface pressure: 150 g / cm ² , time 10 seconds, water volume 10 ml.

Thereafter, the glass 20 is pulled upward at a constant speed (tensile speed: 200 mm / min), and the peel strength when the glass 20 peels off the backing material 1 is measured by the autograph 23.

In the measurement of the wet state, after pure water was dropped on the backing surface, the surface of the backing material 1 was wiped off to remove the water on the surface, and then the glass 20 was adsorbed. 1.2 Horizontal Load As shown in FIG. 5, a predetermined load is applied to cause the glass 20 to be adsorbed to the backing material 1 fixed to the surface plate. afterwards,
With the load applied, pull the glass 20 in the horizontal direction,
The intensity at which the glass 20 starts to move is measured by the autograph 23.

With respect to the wet state, pure water was dropped on the glass surface in the same manner as in the vertical direction measurement, and the surface was wiped. Pressing conditions and tensile conditions were the same as in the case of vertical load. 2. Measurement of Roughness (Surface Roughness) of Resin Layer Surface The measurement was performed under the following conditions using SURFCOM manufactured by Tokyo Seimitsu Co., Ltd. as a measuring device. Measurement terminal: R5 μm 90 ° conical diamond terminal Measurement length: 12.5 mm Measurement speed: 0.3 mm / sec Measurement load: 0.4 mN (0.04 gf) (Example 1) Foaming of polyurethane resin on polyester film surface A layer (thickness: 30 μm) was formed, and the surface of the foam layer was buffed (surface smoothing) to have a constant surface roughness (irregularities). Next, the surface of the foam layer was coated with a thermosetting urethane resin. Before the resin is completely cured, a film (separator) having a large number of irregularities having a surface roughness Ra of 0.3 (U70) μm is pressed with a hot roll to cure the resin layer. The film was peeled off from the surface of the resin layer to obtain a backing material.

When the unevenness of the resin layer surface of the obtained backing material was measured, it was 0.6 (U70) μm.

In the dry or wet state of the backing material in the vertical and horizontal directions, the adsorbing force was continuously measured 5 times and 2 times.
The results of zero measurements are shown in FIGS. (Comparative Example 1) A backing material was obtained in the same manner as in Example 1 except that a film (separator) having many irregularities having a surface roughness Ra of 0.30 µm was used.

The unevenness of the resin layer surface of the obtained backing material was measured and found to be 0.30 μm.

In the dry or wet state of the backing material in the vertical and horizontal directions, the adsorbing force was continuously measured 5 times and 2 times.
6 and 7 show the results of the measurement performed 0 times.

The following can be seen from FIGS.

[0048] Product with minute surface irregularities on resin layer (Example 1)
Has a lower adsorption force in the vertical direction than the surface-untreated product (Comparative Example 1). Further, the suction force in the horizontal direction was almost the same level, although there was a slight decrease.

Regarding the air winding, the sample was actually pasted on a flat surface plate and glass was attached.
Although a slight air residue is observed, when compared with the untreated surface product, it was found that air flow at the time of addition occurred and air escape was clearly improved.

[0050]

According to the present invention, fine irregularities can be formed on the surface of the backing material by transferring the irregularities on the surface of the film (separator) to the surface of the resin layer, so that the production is simple and uniform and fine. Asperities can be formed on the backing material surface.

The backing material obtained according to the present invention comprises:
After buffing the base material surface of the backing material, laminating a resin on the surface layer improves thickness accuracy, and thereby eliminates transfer streaks on the workpiece (glass etc.), improving flatness and undulation I do. Therefore, transfer of surface defects of the backing material to the object to be polished can be eliminated, and the surface accuracy of the object to be polished can be improved. Further, the use of the template can be eliminated by increasing the attraction force to the object to be polished.

Further, since the adhesive resin layer is laminated on the surface of the elastic layer, the following effects can be obtained. (1) Water-repellent effect: The adhesive resin layer plays a role as a blocking layer against liquid intrusion, so that the slurry does not enter the inside of the backing material. As a result, the problem of scorching of the back surface of the substrate, which has been a problem with the conventional backing material, and uneven wetting of the slurry in the backing material (centrifugal and centripetal effects due to the rotational movement of the carrier head on the slurry in the backing material)
Substrate unevenness after polishing by polishing is eliminated. (2) Surface smoothness By laminating a resin layer (top coat layer) with good surface smoothness on the elastic layer with excellent thickness accuracy by buffing, By the action of the intermolecular force, a much stronger adsorption force (vertical direction, shear direction) is generated as compared with the conventional backing material. Since the holding performance does not cause displacement or rotation of the substrate during polishing as in the case of the wax method, there is an advantage that the flatness of the substrate after polishing (particularly, suppression of edge dripping at the edge portion) is excellent.

Further, since the resin layer of the backing material has minute irregularities, the following effects are obtained. (3) Air bite between the substrate and the backing material is reduced.

In the case of a backing material having a topcoat layer that has not been subjected to surface treatment, air does not escape in the vertical direction or the horizontal direction. Since fine irregularities were formed on the surface, the suction force and the air bite level could be balanced.

The desorption of the glass is improved by the fine irregularities on the surface, and the adsorbing power is too strong as in the prior art, so that the workability at the time of adsorbing is not reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of an embodiment of a backing material.

FIG. 2 is an explanatory view showing a manufacturing process of the backing material shown in FIG.

FIG. 3 is an enlarged sectional view of the backing material shown in FIG.

FIG. 4 is an explanatory view showing a method of measuring a suction force in a vertical direction.

FIG. 5 is an explanatory diagram showing a method of measuring a suction force in a horizontal direction.

FIG. 6 is a graph showing a measurement result of a suction force in a vertical direction.

FIG. 7 is a graph showing a measurement result of a suction force in a horizontal direction.

FIG. 8 is a sectional view of a main part of a conventional backing material.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Backing material 2 Substrate 3 Elastic layer 4 Adhesive resin layer 5 Pressure-sensitive adhesive layer

Continued on the front page (72) Inventor Katsumasa Kawabata 172 Ikezawa-cho, Yamatokoriyama-shi, Nara Pref.Rodale Nita Co., Ltd. (72) Inventor Naoya Maeda 172 Ikezawa-cho, Yamatokoriyama-shi, Nara Pref. F term (reference) 3C058 AB04 CA01 CA06 CB01 CB02 CB05 CB06 DA17

Claims (2)

[Claims] 1. A method of manufacturing a backing material for holding an object to be polished having a substrate, an elastic layer laminated on the substrate, and an adhesive resin layer laminated on the elastic layer. Before the adhesive resin layer is completely cured, a step of attaching a film having fine irregularities with a surface roughness Ra of 0.4 to 4.0 μm to the surface of the resin layer, and A step of peeling the film from the surface of the adhesive resin layer after the adhesive resin layer is cured. 2. The method for producing a backing material according to claim 1, further comprising the step of buffing the surface of the elastic layer laminated on the surface of the base material to have a constant surface roughness.