JP2003188126A - Method and apparatus for waxless mount polishing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waxless mount polishing method, which holds a plurality of kinds of semiconductor wafers differing in size with one polishing head to lower the cost of a polishing apparatus and can perform polishing with the same polishing precision as before, and its apparatus. <P>SOLUTION: A silicon wafer W for 6 inches is put in the hole part of an adapter template 15 in a template 15 for 8 inches to apparently increase the diameter of the 6-inch wafer W to that of an 8-inch wafer. With one polishing head 12, a plurality of kinds of silicon wafers W of different sizes can be polished with nearly the same polishing precision as before. Further, the need for a plurality of polishing heads by the sizes of wafers is eliminated. Consequently, the polishing apparatus can be made low-cost. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waxless mount type polishing method and apparatus, and more particularly to a waxless mount type polishing technique for mechanically and chemically polishing the surface of a semiconductor wafer held by waxless.

[0002]

2. Description of the Related Art A waxless mount type polishing method is known as one of methods for polishing a silicon wafer.
Hereinafter, a waxless mount type polishing apparatus used for this will be described with reference to the drawings. FIG. 4 is a vertical cross-sectional view of a conventional waxless mount type polishing apparatus. As shown in FIG. 4, the waxless mount type polishing apparatus 10
0 is a polishing surface plate 104 having a polishing cloth 105 spread on the upper surface.
And a single-wafer polishing head 101 having a wafer fixing template 102 provided on the lower surface. The template 102 is attached to the lower surface of the polishing head 101 via a water-holding non-woven back pad 103. During polishing, pure water is supplied to the back pad 103, and the surface tension of the back pad 103 causes template 10
The silicon wafer W housed in the second hole is held from the back surface side. At this time, the silicon wafer W projects downward over the entire polishing surface from the end surface of the template 102 by a predetermined height. Then, the polishing head 101 is rotated on the polishing platen 104 while supplying the polishing agent containing the loose abrasive grains to the polishing surface of the polishing cloth 105,
The polished surface of the silicon wafer W is mirror-polished.

[0003]

However, such conventional waxless mount type polishing has the following disadvantages. That is, only one template 102 such as a template for a 6-inch wafer or a template for an 8-inch wafer is fixed to the lower surface of the back pad 103. As a result, the polishing head 101 was a dedicated head for polishing any one size silicon wafer W. Therefore, it is necessary to prepare polishing heads 101 having different sizes for each polishing apparatus, the number of which is the size (diameter) of the silicon wafer W to be handled.

[0004]

SUMMARY OF THE INVENTION Therefore, according to the present invention, a single polishing head can be used to hold a plurality of types of semiconductor wafers having different sizes, which can reduce the cost of the polishing apparatus and can reduce the cost of the conventional polishing apparatus. An object of the present invention is to provide a waxless mount type polishing method and an apparatus therefor capable of polishing with the same polishing accuracy.

[0005]

According to a first aspect of the present invention, a semiconductor wafer is housed inside an annular template, and a back pad is interposed between the semiconductor wafer and a polishing head to form the semiconductor wafer. In the waxless mount polishing method for polishing, an annular adapter template having an outer diameter substantially the same as the inner diameter of the template and an inner diameter substantially the same as the semiconductor wafer is prepared, and the semiconductor wafer is housed inside the adapter template. Then, the back side of the semiconductor wafer and the back side of the adapter template are connected by an adhesive tape to produce a wafer with an adapter, and the template with the adapter is housed inside the template to polish the semiconductor wafer Waxless mount It is a polishing method.

The polishing head is disposed above and above a polishing platen having a polishing cloth spread on its upper surface. The polishing head may be a single-wafer type in which one semiconductor wafer is held on the surface facing the polishing platen, or a batch-type in which a large number of semiconductor wafers are collectively held. Further, the polishing head may be a system that reciprocates along the polishing cloth, or a system that does not reciprocate. In the case of reciprocating movement, a part of the outer peripheral portion of the semiconductor wafer may be projected to the outside of the polishing cloth for polishing, or may not be polished. The polishing head may be disposed above the polishing platen so as to face it, or may be upside down. Further, a vertical polishing apparatus in which the axial directions of the polishing head and the polishing platen are horizontal may be used.

The inner diameter of the template is not limited. However, among a plurality of types of semiconductor wafers having different diameters to be polished, the diameter is preferably slightly larger than the diameter of the largest diameter semiconductor wafer. This is because the adapter template is used to accommodate the semiconductor wafers of all remaining sizes in the holes. As a material for the back pad, for example, a nonwoven fabric such as suede cloth can be adopted.
Further, its hardness is not limited. Then, only a part (for example, the outer peripheral portion) of the back pad may have a higher hardness than the central portion thereof. The thickness of the back pad is not limited. However, it is preferably 2 mm or less. If it exceeds 2 mm, the back pad tends to have uneven hardness.

It is necessary to prepare adapter templates having different inner diameters by the number of types of semiconductor wafers held in the holes. However, the outer diameter of each of these adapter templates must be substantially the same as the inner diameter of the template so that they can be accommodated in the holes of the template without rattling. The height of the template and the adapter template is not limited. However, if the height of the semiconductor wafer is about the same as the thickness of the semiconductor wafer,
A height of 0 μm is preferable. The materials of the template and the adapter template are not limited. Examples thereof include glass epoxy resin and various ceramics. The material of the adhesive tape is not limited. For example, a synthetic resin such as acrylic, polyethylene, or polyolefin can be adopted. The thickness of the adhesive tape is not limited. It is preferably about 50 to 100 μm. The adhesive tape may be collectively attached to the entire area of the back surfaces of the adapter template and the semiconductor wafer, or may be attached to only a part thereof. However, in order to integrate the two members, at least a part of them must extend over the adapter template and the semiconductor wafer.

According to a second aspect of the present invention, there is provided a waxless mount type polishing apparatus in which a semiconductor wafer is housed inside an annular template and a back pad is interposed between the semiconductor wafer and the polishing head. While the diameter is almost the same as the inner diameter of the template,
A waxless mount polishing apparatus having an annular adapter template whose inner diameter is substantially the same as that of a semiconductor wafer, and an adhesive tape connecting the back surface side of the semiconductor wafer housed inside the adapter template and the back surface side of the adapter template. is there.

[0010]

According to the present invention, when polishing a semiconductor wafer having a diameter smaller than the inner diameter of the template, the semiconductor wafer is first accommodated inside the adapter template. next,
The back surface of each of the semiconductor wafer and the adapter template is connected by an adhesive tape to produce a wafer with an adapter. After that, when the wafer with adapter is housed inside the template, the wafer with adapter is held from the back surface side thereof by the surface tension of the back pad to which pure water is previously supplied. Then, the semiconductor wafer is polished as usual. In this way, by accommodating the semiconductor wafer having a diameter smaller than the inner diameter of the template inside the adapter template, the diameter of the semiconductor wafer is apparently enlarged to a size substantially the same as the inner diameter of the template.
As a result, a single polishing head can be used to polish a plurality of types of semiconductor wafers having different sizes with substantially the same polishing accuracy as the conventional one. In addition, since it is not necessary to prepare a plurality of polishing heads for each size of the semiconductor wafer for one polishing head as in the conventional case, the cost of the polishing apparatus can be reduced.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below. FIG. 1 is a vertical sectional view of a waxless mount type polishing apparatus according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of a wafer with an adapter according to an embodiment of the present invention. FIG. 3 is a vertical cross-sectional view showing a process of attaching a wafer with an adapter to a polishing head according to an embodiment of the present invention. In FIG. 1, reference numeral 10 is a waxless mount type polishing apparatus (hereinafter, polishing apparatus) according to an embodiment of the present invention. The polishing apparatus 10 includes a polishing platen 11 and a polishing head 12 that is disposed above and facing the polishing platen 11. A polishing cloth 13 is spread on the polishing platen 11. The polishing head 12 has a template 14 for fixing the wafer on the lower surface thereof.

The polishing platen 11 and the polishing head 12 are disk-shaped, and the opposing surfaces are flat surfaces. The polishing platen 11 and the polishing head 12 are rotated about their respective rotation axes by rotating means (not shown). The polishing head 12 moves up and down as the rotary shaft moves up and down. The template 14 is, for example, a circular ring-shaped glass epoxy plate, and is provided on the lower surface of the polishing head 12 via the back pad 15 attached to the lower surface of the polishing head 12. The template 14 has an inner diameter larger than that of an 8-inch wafer by 0.2 to 1.0 mm. The thickness of the template 14 is, for example, the same as that of an 8-inch wafer, or the height at which the wafer protrudes by 1 to 200 μm. The back pad 15 is made of suede, for example,
The thickness is uniform across the pad. The silicon wafer W to be polished is a CZ wafer.

A feature of the present invention is that the adapter template 16 housed in the hole portion of the template 14 is used, and not only the silicon wafer W having the same diameter as the inner diameter of the template 14 but also the silicon having a smaller diameter than the inner diameter of the template 14 is used. The point is that even a wafer W (here, a 6 inch wafer) can be polished by using one polishing apparatus 10. Hereinafter, this will be described in detail. As shown in FIGS. 1 and 2, the outer diameter of the adapter template 16 is smaller than the inner diameter of the template 14 by 0.2 to 1.0 mm. On the other hand, the inner diameter of the adapter template 16 is 0.2 to 10 mm smaller than that of the 6-inch silicon wafer W.
It has a large diameter of 1.0 mm. The thickness of the adapter template 16 is thinner than that of the 6-inch silicon wafer W, and the difference is preferably within 10 μm. The adapter template 16 and the silicon wafer W are integrally attached from the back side of each with an adhesive tape 17 to form a wafer with adapter 18. The adhesive tape 17 is a circular tape made of synthetic resin having an adhesive applied to the back surface, the diameter thereof is substantially the same as the outer diameter of the adapter template 16, and the tape thickness is 50 to 100 μm.

Next, a waxless mount type polishing method for a silicon wafer W using the waxless mount type polishing apparatus 10 according to this embodiment will be described. First, a polishing method for an 8-inch wafer will be described. in this case,
The polishing is the same as the conventional method (see FIG. 4). That is, pure water is supplied to the back pad 15, and the surface tension of the pure water supplies the silicon wafer W accommodated in the hole of the template 14.
Is held from the back side. Then, the polishing head 12 is rotated on the polishing platen 11 while the polishing agent containing the free abrasive grains is supplied to the polishing surface of the polishing cloth 13, and the polishing surface of the silicon wafer W is mirror-polished.

Next, a method of polishing a 6-inch wafer will be described. In this case, first, the silicon wafer W is housed in the hole of the adapter template 16. Next, a large-sized adhesive tape 17 is attached to the back surfaces of the silicon wafer W and the adapter template 16 to integrate them (FIG. 2).
As a result, the wafer with adapter 18 is manufactured. Then, with the adhesive tape 17 side as the back surface, this wafer with adapter 18 is housed inside the template 14 on the back surface side of the polishing head (FIG. 3). As a result, the wafer 18 with the adapter is held from the back surface side by the surface tension of the back pad to which pure water has been supplied in advance. After that, the silicon wafer W is polished as in the case of the 8-inch wafer described above (FIG. 1). In this way, by accommodating the silicon wafer W having a smaller diameter than the inner diameter of the template 14 inside the adapter template 16, the apparent diameter of the silicon wafer W (6 inches) is substantially the same as the inner diameter of the template 14 (8 inches). Inch). As a result, a single polishing head 12 can be used to polish a plurality of types of silicon wafers W having different sizes with substantially the same polishing accuracy as the conventional one. Moreover,
Since it is not necessary to prepare a plurality of polishing heads for each size of silicon wafer for one polishing head as in the conventional case, the cost of the polishing apparatus 10 can be reduced.

[0016]

According to the present invention, a semiconductor wafer having a diameter smaller than the inner diameter of the template is inserted into the adapter template, and the outer diameter of the external wafer is enlarged to a size that can be accommodated in the template. With this polishing head, you can polish multiple types of semiconductor wafers with different sizes with the same polishing accuracy as before, and you do not have to prepare a polishing head for each size of semiconductor wafer. You can

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a waxless mount-type polishing apparatus according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of a wafer with an adapter according to an embodiment of the present invention.

FIG. 3 is a vertical cross-sectional view showing a step of attaching a wafer with an adapter to a polishing head according to an embodiment of the present invention.

FIG. 4 is a vertical cross-sectional view of a waxless mount type polishing apparatus according to a conventional means.

[Explanation of symbols]

10 Waxless mount type polishing machine, 12 polishing head, 14 templates, 15 back pad, 16 adapter templates, 17 Adhesive tape, W Silicon wafer (semiconductor wafer).

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Taira Sato             3-5-1 Otemachi, Chiyoda-ku, Tokyo             Ryo Material Silicon Co., Ltd. F-term (reference) 3C058 AA07 AB04 CB01 DA17

Claims (2)

[Claims] 1. A waxless mount type polishing method in which a semiconductor wafer is housed inside an annular template, and a back pad is interposed between the semiconductor wafer and a polishing head to polish the semiconductor wafer. An annular adapter template having a diameter substantially the same as that of the template and an inner diameter substantially equal to that of the semiconductor wafer is prepared, and the semiconductor wafer is housed inside the adapter template. A waxless mount polishing method in which a wafer with an adapter is produced by connecting the back side with an adhesive tape, and the template with an adapter is housed inside the template to polish a semiconductor wafer. 2. A waxless mount type polishing apparatus in which a semiconductor wafer is housed inside an annular template and a back pad is interposed between the semiconductor wafer and a polishing head, the outer diameter being the inner diameter of the template. Wax provided with an annular adapter template having substantially the same inner diameter as that of the semiconductor wafer, and an adhesive tape connecting the back side of the semiconductor wafer housed inside the adapter template and the back side of the adapter template. Less mount type polishing machine.