JP2002355756A - Backing material for holding polished object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a backing material that can improve the surface accuracy of a polished object by eliminating the transfer of a surface defect of the backing material to the polished object and can eliminate the use of a template. SOLUTION: This backing material 1 for holding the polished object 6 has a base material 2, an elastic foam layer 3 laminated on the base material 2, and a resin layer 4 laminated on the foam layer 3. The foam layer 3 is formed of polyurethane resin or the like, and the resin layer is preferably formed of a thermoplastic resin.

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, LCD, a disk, etc., and holding these polished objects. For backing material used to keep.

[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 the polishing is deteriorated after being transferred as dimples, and that it takes much time to attach and detach.

(2) In the conventional vacuum chuck method, an object to be polished bends to the suction port side near a suction port formed by machining, and conversely, the surface of the object to be polished after polishing has a surface which is polished. The removal is left as a projection point that was insufficient, worsening 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 11 used here is, for example, as shown in FIG. 3, a DMF solution layer of a urethane resin coated on a base material 12, which is solidified in water, washed in warm water, and dried with hot air. The foamed layer 13 is formed by smoothing the surface. In the drawing, reference numeral 6 denotes an object to be polished, and 14 denotes a pressure-sensitive adhesive layer.

However, since the surface accuracy of the holding surface of the backing material 11 reflects the coating accuracy and defects of the coater, the surface accuracy is lower than that of the backing material whose surface is 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.

[0013]

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 backing material capable of improving the surface accuracy of a polished object.

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

[0015]

A backing material for holding an object to be polished according to the present invention comprises a substrate, an elastic foam layer laminated on the substrate, and an elastic foam layer laminated on the foam layer. And the above-mentioned object is achieved.

In one embodiment, the foam layer is a foam layer made of a polyurethane resin, and the resin layer is made of a thermosetting resin or a thermoplastic resin.

In one embodiment, the resin layer has a hardness of 48 to 88 (JIS A hardness) and a compression ratio of 3 to 3.
~ 52% (measured by JIS L1096).

The operation of the present invention is as follows.

The thickness of the conventional backing material surface is poor, 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 workpiece.

Therefore, in the present invention, the holding surface of the backing material is smoothed, and thereafter, 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 adhesiveness 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 worked and to reduce the holding force, and to damage the object to be polished. Can be prevented.

[0021]

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

As shown in FIGS. 1 to 3, a backing material 1 of the present invention comprises a base material 2, an elastic foam layer 3 laminated on the base material 2, and a laminate layer on the foam layer 3. Adhesive resin layer 4 and a pressure-sensitive adhesive layer 5 laminated on the back surface of the substrate 2
And 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 foamed layer 3, a foamed layer of the backing material 1 which has been conventionally used can be used. 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 foam layer 3 is smoothed, and the surface of the foam layer 3 has a large number of independent foaming suction holes. The compression ratio of the foam layer 3 is 5 to 60.
% (Measured by JIS L1096) is preferred.

The adhesive resin layer 4 laminated on the surface of the foam 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 from 48 to 88 (JIS-A, J
ISK6301 (measured by 5.2 (A type)), and the compression ratio is preferably 3 to 52%.

In order to polish an object to be polished such as a semiconductor wafer, water is adsorbed on the lower surface of the resin layer 4 of the backing material 1 with the surface of the object to be polished facing down, and the holding device is lowered in the holding state. The surface of the polishing pad on the lower platen is pressurized at a predetermined pressure to rotate the platen, the slurry is supplied from a nozzle, and the holding plate holding the workpiece is rotated to polish the polishing surface of the workpiece. I do.

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

Further, since the foamed layer 3 is formed on the back surface of the self-adhesive resin layer 4, even if polishing dust or the like is 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.

[0029]

According to the present invention, after buffing the base material surface of the backing material, the resin is laminated on the surface of the backing material, so that the thickness accuracy is improved. And flatness and undulation are improved. Therefore, the transfer of the surface defect 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.

[Brief description of the drawings]

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

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

FIG. 3 is a sectional view of a main part of a conventional backing material.

[Explanation of symbols]

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

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Katsumasa Kawabata 172 Ikezawa-cho, Yamatokoriyama-shi, Nara Prefecture Inside the Rodale Nita Plant (72) Inventor Naoya Maeda 172 Ikezawacho, Yamatokoriyama-shi, Nara Prefecture Rodel Nita Corporation Nara Factory (72) Inventor Kunihiro Fujiyama 172 Ikezawa-cho, Yamatokoriyama City, Nara Prefecture Rodel Nita Corporation Nara Factory F-term (reference) BA03 BA07 BA10A BA10C CB00C DJ01B DJ02 EJ27 GB90 JB13C JB16C JK07C JK12C JL13C

Claims (4)

[Claims] 1. A backing material for holding an object to be polished having a substrate, an elastic foam layer laminated on the substrate, and an adhesive resin layer laminated on the foam layer. . 2. The backing material according to claim 1, wherein the foamed layer is a foamed layer made of a polyurethane resin, and the adhesive resin layer is made of a thermosetting resin or a thermoplastic resin. 3. The resin layer has a hardness of 48 to 88 (JIS).
The backing material according to claim 1 or 2, wherein the compression ratio is 3 to 52%. 4. A backing material for holding an object to be polished having a base material and an elastic adhesive resin layer laminated on the base material.