JPH10150009A - Wafer polishing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer polishing apparatus for polishing a wafer in a state where the wafer is attracted to a head, in which a head provided with an opening for circulating a medium on a wafer attracting surface has irregularities on the wafer. It is difficult to flatten the surface to be polished of a later wafer. A head (50) having a top plate (52) attached to a head body (51) supported on a support shaft (56).
A polishing apparatus for polishing a wafer while adsorbing a wafer 60 thereon, wherein an opening 53 for flowing a medium is formed along the outer peripheral edge of a flat wafer suction surface 52a of a top plate 52. The opening 53 communicates with a medium passage 55 formed inside the head 50. Further, a guide ring 54 is provided on the head 50 along the outer periphery of the opening 53. The guide ring 54 has a projection 54a facing inward while forming a gap 53a communicating with the opening 53, thereby facilitating the flow of the medium between the suction surface 52a and the wafer 60.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a wafer polishing apparatus.

[0002]

2. Description of the Related Art In general, there are various types of wafer polishing apparatuses.
Hereinafter, an example of a commonly used wafer polishing apparatus will be described with reference to FIGS. FIG. 5 is a fragmentary sectional view of the main part of the polishing apparatus during wafer suction, and FIG. 6 is a top view of the head of the polishing apparatus.

First, as shown in FIG. 5, for example, an ordinary wafer polishing apparatus polishes a wafer 20 on a top plate 11 which is a part of a head 10 while adsorbing a wafer 20 from a surface opposite to a surface to be polished. I do.

[0004] As shown in the figure, the wafer 20 attracted to the top plate 11 is polished while maintaining the state. First, the head 10 is supported by a spindle supporting the head 10.
While rotating, approaches the opposing polishing pad 31.
Accordingly, the wafer 20 adsorbed on the top plate 11 of the head 10 also approaches the polishing pad 31 while rotating,
Polishing starts when the polished surface of the wafer 20 contacts the polishing pad 31.

[0005] During polishing, the head 10 holding the wafer 20 is constantly rotating. For this reason, the head 10 is provided with a guide ring 13 in order to prevent the wafer 20 from being displaced from the top plate 11 due to the rotation.

As shown in FIG. 6, an opening 12 is formed in the head 11 of the polishing apparatus on a suction surface of a top plate 11 for sucking a wafer 20. Therefore, when the wafer 20 is attracted to the top plate 11, the opening 12 is formed on the surface of the wafer 20 opposite to the surface to be polished.
Exists.

When the wafer 20 is attracted to the top plate 11 by using the polishing apparatus, for example, a vacuum chuck is usually used. In the vacuum chuck, the opening 20 provided in the top plate 11 is set to a negative pressure so that the wafer 20
Is sucked toward the head 10, thereby attracting the wafer 20 to the top plate 12.

When the above-mentioned polishing apparatus is used, the stress applied to the surface of the wafer 20 opposite to the surface to be polished is concentrated on the lower portion of the opening 12. Therefore, the portion of the wafer 20 sucked by the opening 12 is more strongly sucked than other portions.

That is, the top plate 1 is placed on the wafer 20.
There is a portion that is relatively strongly attracted to 1 and a portion that is relatively weakly attracted, and these portions cause the wafer 20 to have irregularities. Even if the wafer 20 is polished with these irregularities, it is difficult to flatten the polished surface of the wafer 20 by polishing.

Therefore, unlike the vacuum chuck, the opening 1
For example, a hydro chuck that attracts the wafer 20 to the top plate 11 without setting the negative pressure to 2 is also used. In the hydro chuck, a liquid is filled between the lower surface of the top plate 11 and the surface opposite to the surface to be polished of the wafer 20, and the wafer 20 is attracted to the top plate 11 by the surface tension of the liquid.

[0011]

However, even if the wafer 20 is sucked using a liquid like a hydro chuck, the wafer 20 is sucked by the openings 12 formed in the top plate 11 shown in FIG. The unevenness of the wafer 20 caused by the wafer 12 does not disappear.

That is, in either case of the vacuum chuck or the hydro chuck, the opening is formed in the wafer 2.
0, the wafer 20 has the top plate 1
There is a part that is relatively strongly adsorbed on the part 1 and a part that is relatively weakly adsorbed on the part 1. Therefore, the wafer 20 having unevenness
It is difficult to flatten the surface to be polished of the wafer 20 by polishing.

[0013]

SUMMARY OF THE INVENTION The present invention is a wafer polishing apparatus made to solve the above-mentioned problems.

That is, the head includes a head body supported by a spindle, a top plate attached to the head body, and a guide ring formed along the outer periphery of the lower surface of the top plate.
An opening through which a medium flows is formed on the outer periphery of the wafer suction surface of the top plate, and the opening communicates with the medium passage of the top plate and the head main body, and also communicates with a gap between the guide rings. The wafer polishing apparatus is characterized in that the lower part of the ring projects inward without closing the gap leading to the opening.

The opening of the top plate is formed in an annular shape along the outer peripheral edge of the wafer suction surface of the top plate, or is formed in a plurality of openings opened at equal intervals.

Unlike the conventional polishing apparatus, when the wafer is attracted to the top plate, the opening of the top plate is located outside the wafer. From this, the medium for suction first flows from the opening formed in the top plate to the side circumference of the wafer, and gradually flows between the opposite surface of the polished surface of the wafer and the wafer suction surface of the top plate. .

As a result, the surface opposite to the surface to be polished of the wafer is in contact with the entire surface along the wafer suction surface of the top plate without any gap, or is in contact with the entire surface via a medium having the same thickness. Therefore, no irregularities are formed on the wafer surface, and therefore, the surface to be polished can be easily flattened by polishing.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic structural cutaway view of the head of the polishing apparatus, and FIG. FIG. 3 is a main part cutaway view of the polishing apparatus during wafer suction, and FIG. 4 is a main part cutaway view of the polishing apparatus during wafer polishing.

First, as shown in FIG. 1, the wafer polishing apparatus includes a column-shaped head 50 for holding a wafer 60. The head 50 is supported by a support shaft 56 formed at the center of the upper surface.
Reference numeral 6 is connected to a rotating shaft (not shown) of a motor for rotating the head 50.

The head 50 has a top plate 52 made of ceramics or the like attached to the lower surface of the head body 51, and sucks the wafer 60 on a wafer suction surface 52a formed on the top plate 52. An opening 53 is formed on the outer peripheral edge of the wafer suction surface 52a.

Further, an annular guide ring 54 is provided on the top plate 52 along the outer periphery of the opening 53. Then, the top plate 52 is attached to the wafer 6
In order to make the guide ring 54 and the wafer 60 adhere to each other, the lower part of the guide ring 54 is protruded inward in a direction parallel to the surface to be polished of the wafer 60 as shown in FIG. A gap 53a is formed between the wafer suction surfaces 52a.

The structure of the opening 53 will be described with reference to a partial sectional view of FIG. 2A. The opening 53 is formed in an annular shape along the outer peripheral edge of the wafer suction surface 52a. Alternatively, as another example of the opening, as shown in FIG. 2B, it is possible to form the opening 53 with a plurality of equally spaced openings on the outer peripheral edge of the wafer suction surface 52a. .

In any case, the wafer suction surface 52a is
Has a shape such that the entire surface to be polished is adsorbed. That is, the projection 54 a of the guide ring 54 is
A gap 53a is formed so as to cover a part of the gap 3a.

On the other hand, the wafer 60 is arranged with its polished surface facing downward. The wafer suction surface 52a of the top plate 52 approaches the wafer 60 from above. At this time, the medium is not circulated through the opening 53.

Further, the head 50 is moved closer to the wafer 60. With the top plate 52 approaching the wafer 60 in this manner, the medium is circulated through the opening 53. For example, in the case of water as a medium to be circulated, about 10 cm ³ per minute flows out of the opening 53 through the medium passage 55.

As described above, the medium flowing from the opening 53 to the side circumference of the wafer 60 is
In this state, the wafer suction surface 52 a of the top plate 52 approaches the wafer 60.

As a result, the suction surface 52 of the top plate 52
The wafer 60 is in uniform contact with a through a medium having a uniform thickness or with a medium having a uniform thickness. Therefore, the top plate 52
No irregularities are formed on the wafer 60 that has been sucked.

The projection 54a of the guide ring 53 is formed to project inward, so that the wafer 60 adsorbed on the adsorption surface 52a is formed.
The protrusion 54a is present on the outer periphery of. If the gap 53a formed between the projection 54a and the wafer suction surface 52a is made smaller than the opening 53, the medium hardly flows to the outside of the head 50 from the opening 53 through the side circumference of the wafer 60. Instead, circulation between the top plate 52 and the wafer 60 becomes easier.

Therefore, even if the opening 53 does not exist on the suction surface 52a, the wafer 60 is uniformly sucked on the suction surface 52a of the top plate 52.

As shown in FIG. 3, the wafer 60 is moved from the position where it is placed onto the polishing pad 71 placed on the polishing platen 72 while being held on the top plate 52 by the medium. You.

Then, as shown in FIG. 4, even during polishing, the wafer 60 is adsorbed on the top plate 52 without unevenness, and is polished while being pressed against the polishing pad 71.

[0032]

As described above, according to the present invention,
An opening is provided for flowing the medium along the outer peripheral edge of the wafer suction surface of the top plate of the head. Conventionally, there has been a problem that unevenness occurs on the wafer sucked to the top plate, but in the present invention, the wafer is uniformly sucked along the flat wafer suction surface of the top plate,
No irregularities occur on the wafer. As a result, the wafer is polished in a flat state, and the polished surface of the polished wafer can be easily formed uniformly. As described above, the wafer can be polished flatter than before. Moreover, conventionally, a medium called a backing pad for sucking a wafer is attached to the top plate while covering the opening on the top plate.
Although the wafer may be polished uniformly by forming the backing pad uniformly, it is not necessary to use the backing pad in the present invention. Therefore, the maintenance management related to the backing pad is unnecessary, and the economic efficiency is higher than before.

[Brief description of the drawings]

FIG. 1 is a schematic structural cutaway view of a head in a wafer polishing apparatus according to the present invention.

FIG. 2 is a partial cross-sectional view of the head of the wafer polishing apparatus according to the present invention when looking up;

FIG. 3 is a fragmentary cutaway view of the polishing apparatus during wafer suction according to the present invention.

FIG. 4 is a fragmentary cutaway view of a polishing apparatus during wafer polishing according to the present invention.

FIG. 5 is a main part cutaway view of a polishing apparatus during wafer suction in a conventional example.

FIG. 6 is a head elevation view of a conventional wafer polishing apparatus.

[Explanation of symbols]

Reference Signs List 50 head 51 head main body 52 top plate 52a wafer suction surface 53 opening 53a gap 54 guide ring 54a projection 55 medium passage 56 support shaft 60 wafer

Claims (3)

[Claims] 1. A head comprising: a head body supported by a support shaft; a top plate attached to the head body; and a guide ring formed along an outer periphery of a lower surface of the top plate. An opening through which a medium flows is formed on the outer periphery of the wafer suction surface of the top plate; the opening communicates with the medium passage of the top plate and the head body and also communicates with the gap of the guide ring; An apparatus for polishing a wafer, characterized in that the lower part of the ring projects inward without closing the gap leading to the opening. 2. The wafer polishing apparatus according to claim 1, wherein the opening of the top plate is formed in an annular shape along an outer peripheral edge of a wafer suction surface of the top plate. apparatus. 3. The wafer polishing apparatus according to claim 1, wherein the openings of the top plate are formed in a plurality of openings opened at equal intervals along an outer peripheral edge of a wafer suction surface of the top plate. An apparatus for polishing a wafer, comprising: