JP4019349B2 - Waxless mount polishing machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a waxless mount type polishing apparatus , and more particularly to a waxless mount type polishing technique for performing mechanical chemical polishing on the surface of a semiconductor wafer held in a waxless manner.
[0002]
[Prior art]
A waxless mount type polishing method is known as a kind of polishing method for silicon wafers. Hereinafter, a waxless mount type polishing apparatus used for this will be described with reference to the drawings. FIG. 4 is a longitudinal sectional view of a conventional waxless mount type polishing apparatus.
As shown in FIG. 4, a waxless mount type polishing apparatus 100 includes a single-wafer polishing head 101 having a polishing surface plate 104 with a polishing cloth 105 spread on the upper surface and a wafer fixing template 102 on the lower surface. And. The template 102 is attached to the lower surface of the polishing head 101 via a non-woven fabric back pad 103 having water retention.
At the time of polishing, pure water is supplied to the back pad 103, and the silicon wafer W accommodated in the hole of the template 102 is held from the back surface side by the surface tension. At this time, the silicon wafer W protrudes downward from the end surface of the template 102 by a predetermined height over the entire polished surface.
Then, the polishing head 101 is rotated on the polishing surface plate 104 while supplying the polishing agent containing free abrasive grains to the polishing surface of the polishing cloth 105, and the polishing surface of the silicon wafer W is mirror-polished.
[0003]
[Problems to be solved by the invention]
However, such conventional waxless mount type polishing has the following disadvantages.
That is, only one template 102 such as a 6-inch wafer template or an 8-inch wafer template is fixed to the lower surface of the back pad 103. As a result, the polishing head 101 is a dedicated head for polishing any one size of the silicon wafer W. Therefore, it is necessary to prepare polishing heads 101 having different sizes by the number of types (diameters) of silicon wafers W to be handled per polishing apparatus.
[0004]
OBJECT OF THE INVENTION
Therefore, the present invention can hold a plurality of types of semiconductor wafers having different sizes using a single polishing head, thereby reducing the cost of the polishing apparatus and polishing with the same polishing accuracy as in the prior art. to provide a wax-less mounting type polishing apparatus capable of a child, and an object of the present invention.
[0005]
[Means for Solving the Problems]
The invention according to claim 1 is a waxless mount type polishing apparatus in which a semiconductor wafer is accommodated inside an annular template and a back pad is interposed between the semiconductor wafer and a polishing head. An annular adapter template that is 0.2 to 1.0 mm smaller than the inner diameter of the template and has the same inner diameter as that of the semiconductor wafer, a thickness of 50 to 100 μm, and a diameter that is the same as the outer diameter of the adapter template. Waxless mount type polishing apparatus comprising an adhesive tape for connecting a back surface side of a semiconductor wafer accommodated inside an adapter template and a back surface side of the adapter template so that the center line of the adapter template matches the center line It is.
[0006]
The polishing head is disposed to face an upper surface of a polishing surface plate having a polishing cloth spread on the upper surface. This polishing head may be a single wafer type in which one semiconductor wafer is held on the surface facing the polishing surface plate, or a batch type in which a large number of semiconductor wafers are held together. The polishing head may be reciprocated along the polishing cloth or may be non-reciprocal. When reciprocating, a part of the outer peripheral portion of the semiconductor wafer may be protruded outside the polishing cloth and may or may not be polished. The polishing head may be disposed above the polishing surface plate, or may be upside down. Further, it may be a vertical polishing apparatus in which the axial directions of the polishing head and the polishing surface plate are horizontal.
[0007]
The inner diameter of the template is not limited. However, among a plurality of types of semiconductor wafers having different diameters to be polished, it is preferable that the diameter is slightly larger than the diameter of the largest semiconductor wafer. This is because the adapter template is used to accommodate all remaining size semiconductor wafers in the holes.
As a material for the back pad, for example, a nonwoven fabric such as a suede cloth can be employed. Moreover, the hardness is not limited. Then, only a part (for example, the outer peripheral portion) of the back pad may be harder than the central portion.
The thickness of the back pad is not limited. However, 2 mm or less is preferable. If it exceeds 2 mm, hardness unevenness tends to occur on the back pad.
[0008]
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 diameters of these adapter templates need to be substantially the same as the inner diameter of the template so that they can be accommodated in the holes of the template without backlash.
The height of the template and the adapter template is not limited. However, the height which is substantially the same as the thickness of the semiconductor wafer or the height at which the semiconductor wafer protrudes 1 to 200 μm is preferable.
The material of the template and the adapter template is not limited. For example, a glass epoxy resin, various ceramics, etc. are mentioned.
The material of the adhesive tape is not limited. For example, synthetic resins such as acrylic, polyethylene, and polyolefin can be used.
The thickness of the adhesive tape is not limited. About 50-100 micrometers is preferable.
The adhesive tape may be attached all over the back surface of the adapter template and the semiconductor wafer, or may be attached only to a part thereof. However, in order to integrate both members, at least one part must straddle the adapter template and the semiconductor wafer.
[0009]
[Action]
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 surfaces of the semiconductor wafer and the adapter template are connected with an adhesive tape to produce a wafer with an adapter. Thereafter, when the wafer with the adapter is accommodated inside the template, the wafer with the adapter is held from the back side by the surface tension of the back pad to which pure water has been supplied in advance. Thereafter, the semiconductor wafer is polished as usual.
In this way, by accommodating a 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 substantially the same size as the inner diameter of the template. Thereby, it is possible to polish a plurality of types of semiconductor wafers having different sizes with a polishing accuracy substantially the same as the conventional one using a single polishing head. Moreover, since it is not necessary to prepare a plurality of polishing heads according to the size of the semiconductor wafer with respect to one polishing head as in the prior art, the cost of the polishing apparatus can be reduced.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below.
FIG. 1 is a longitudinal sectional view of a waxless mount type polishing apparatus according to one embodiment of the present invention. FIG. 2 is an exploded perspective view of the wafer with an adapter according to one embodiment of the present invention. FIG. 3 is a longitudinal sectional view showing a process of attaching the wafer with an adapter to the polishing head according to one embodiment of the present invention.
In FIG. 1, reference numeral 10 denotes a waxless mount type polishing apparatus (hereinafter referred to as a polishing apparatus) according to an embodiment of the present invention. The polishing apparatus 10 includes a polishing surface plate 11 and a polishing head 12 disposed above and facing the polishing platen 11. A polishing cloth 13 is stretched on the polishing surface plate 11. The polishing head 12 is provided with a wafer fixing template 14 on the lower surface thereof.
[0011]
The polishing surface plate 11 and the polishing head 12 are disk-shaped, and the opposing surfaces are flat surfaces. The polishing surface plate 11 and the polishing head 12 are rotated by rotating means (not shown) around the respective rotation axes. The polishing head 12 moves up and down by raising and lowering the rotation shaft.
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 a back pad 15 attached to the lower surface of the polishing head 12. The template 14 has an inner diameter that is 0.2 to 1.0 mm larger than that of an 8-inch wafer, for example. The thickness of the template 14 is, for example, the same as that of an 8-inch wafer or a height at which the wafer protrudes 1 to 200 μm.
The back pad 15 is made of, for example, suede, and the thickness is uniform throughout the pad. The silicon wafer W to be polished is a CZ wafer.
[0012]
The feature of the present invention is that the adapter template 16 accommodated in the hole of the template 14 is used, and not only the silicon wafer W having a diameter substantially the same as the inner diameter of the template 14 but also the silicon wafer W ( Here, even a 6-inch wafer) can be polished by using one polishing apparatus 10.
This will be described in detail below. 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 1.0 mm larger than that of the 6-inch silicon wafer W. The adapter template 16 is thinner than 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 by adhesive tape 17 from the respective back surfaces to constitute a wafer 18 with an adapter.
The pressure-sensitive adhesive tape 17 is a synthetic resin circular tape whose adhesive is applied to the back surface, and has a diameter substantially the same as the outer diameter of the adapter template 16 and a tape thickness of 50 to 100 μm.
[0013]
Next, a waxless mount polishing method for the silicon wafer W using the waxless mount 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 silicon wafer W accommodated in the hole of the template 14 is held from the back side by the surface tension. Then, the polishing head 12 is rotated on the polishing surface plate 11 while supplying a polishing agent containing free abrasive grains to the polishing surface of the polishing cloth 13, and the polishing surface of the silicon wafer W is mirror-polished.
[0014]
Next, a 6-inch wafer polishing method will be described. In this case, first, the silicon wafer W is accommodated in the hole of the adapter template 16. Next, a large-sized adhesive tape 17 is attached to and integrated with the back surfaces of the silicon wafer W and the adapter template 16 (FIG. 2). Thereby, the wafer 18 with an adapter is produced. And the adhesive tape 17 side is made into the back surface, and this wafer 18 with an adapter is accommodated inside the template 14 of the back surface side of a polishing head (FIG. 3). Thereby, the wafer 18 with an adapter is hold | maintained from the back surface side by the surface tension of the back pad to which the pure water was supplied previously. Thereafter, 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 diameter smaller than the inner diameter of the template 14 inside the adapter template 16, the apparent diameter (6 inches) of the silicon wafer W is substantially the same size as the inner diameter of the template 14 (8 Inch). As a result, a single polishing head 12 can be used to polish a plurality of types of silicon wafers W of different sizes with substantially the same polishing accuracy as conventional. Moreover, since it is not necessary to prepare a plurality of polishing heads according to the size of the silicon wafer with respect to one polishing head as in the prior art, the cost of the polishing apparatus 10 can be reduced.
[0015]
【The invention's effect】
According to this invention, a semiconductor wafer having a diameter smaller than the inner diameter of the template is inserted into the adapter template, and the external wafer diameter is expanded to a size that can be accommodated in the template. A plurality of types of semiconductor wafers having different sizes can be polished with conventional polishing accuracy, and a polishing head need not be prepared for each size of the semiconductor wafer, and the cost of the polishing apparatus can be reduced.
[Brief description of the drawings]
FIG. 1 is a longitudinal 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 longitudinal sectional view showing a process of attaching a wafer with an adapter to a polishing head according to one embodiment of the present invention.
FIG. 4 is a longitudinal sectional view of a waxless mount type polishing apparatus according to a conventional means.
[Explanation of symbols]
10 Waxless mount type polishing equipment,
12 polishing head,
14 templates,
15 Back pad,
16 Adapter template,
17 Adhesive tape,
W Silicon wafer (semiconductor wafer).

Claims (1)

In the waxless mount type polishing apparatus in which the semiconductor wafer is accommodated inside the annular template and the back pad is interposed between the semiconductor wafer and the polishing head,
An annular adapter template whose outer diameter is 0.2 to 1.0 mm smaller than the inner diameter of the template and whose inner diameter is the same as that of the semiconductor wafer;
The adapter template has a thickness of 50 to 100 μm and a diameter that is the same as the outer diameter of the adapter template, and the back side of the semiconductor wafer accommodated inside the adapter template and the back side of the adapter template. A waxless mount type polishing apparatus provided with an adhesive tape that is connected to a center line of the tape so that the center line coincides with the center line.

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