JPH029569A - Lap surface reference plate - Google Patents

Abstract

PURPOSE:To reduce thermal deformation of a lap surface by a method wherein a means to approximately uniformize temperature distribution in the direction of the thickness of a base plate part is mounted to a lap cell part. CONSTITUTION:Grooves 11 with a deep depth are formed in a lap cell part 14, and a ratio d/B of a groove depth (d) to a width B of the lap cell part is increased. As a result, since a quantity (q) of heat flows mainly in the direction of a side 15 of the lap cell part 14, inflow of heat to a base plate part 13 of lapping machine is prevented from occurring, temperature distribution in the direction of thickness is approximately uniformized at the base plate part 13, and thermal deformation is prevented from occurring to the base plate part 13. In the lap cell part 14, axially symmetrical type temperature distribution occurs to the lap cell part 14 and a temperature difference is produced, but the lap cell part 14 is separated by the grooved 11. Further, since the width B of the lap cell part 14 is low compared with the diameter of a lap surface plate, deformation of the lap cell part 14 can be ignored. Thus, thermal deformation of a lap surface 10 is reduced sharply.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a lapping plate, and more particularly to a lapping plate used in a lapping machine for polishing, for example, silicon wafers.

PRIOR TECHNOLOGY AND PROBLEMS TO BE INVENTION This type of lap surface plate is, for example, shown in FIGS. 1 and 2.
The one shown in the figure is known.

In the same figure, the surface of the lap surface plate (lap surface) (10)
A plurality of grooves (11) are formed at right angles to each other, and the lap surface plate is separated from the base plate portion (13) on the back surface (12) side from the bottom of the groove (11) by the groove (11). It is divided into a plurality of wrap cell parts (14). To give an example of the dimensions, the overall thickness H of the lap surface plate is 45 mm, the height of the lap cell part (14), that is, the depth of the groove (11) (groove depth) d is 15 to 17 mm,
The width B of the wrap cell portion (14) (wrap cell portion width) is at most 40 mm (see FIG. 3).

In such a conventional lapping surface plate, the ratio (d/B) between the groove depth d and the lap cell width B is small, so as shown in Fig. 3, the heat Qq generated by lapping is absorbed by the lapping surface (
10) to the base plate part (13) side, a large temperature gradient is generated in the thickness direction within the base plate part (13), and the lap surface plate has a central part that is connected to the lap surface (10).
It is thermally deformed into a convex spherical shape that protrudes to the side. The radius R of this thermal deformation is expressed by the following equation (1), assuming that the periphery of the lap surface plate is in a free state.

R-t/α・θ ・・・・・・・・・ (1) In the above formula, t is the thickness of the base plate (base plate thickness), α is the linear expansion coefficient of the lap surface plate, θ represents the temperature difference between the front side and the back side of the base plate portion (13).

As is clear from equation (1), in order to reduce thermal deformation (increase R) while keeping t constant, it is necessary to reduce α and θ.

However, in the case of the lap surface plate described above, the temperature difference θ of the base plate portion (13) is large, so that thermal deformation is large.

For this reason, at present, idle operation is performed until the ζ-thermal steady state is reached at the start of work.

In addition, repairing the lap surface plate requires highly skilled work as it is necessary to take thermal deformation into consideration.Furthermore, as the plate thickness changes due to wear of the lap surface plate, the amount of thermal deformation also changes. In particular, there is a need for a lapping surface plate that is less prone to thermal deformation in large lapping machines.

An object of the present invention is to provide a lapping surface plate that solves the above-mentioned problems and has minimal thermal deformation.

Means for Solving the Problems A lap surface plate according to the present invention has a plurality of mutually intersecting grooves formed on its surface, and includes a base plate part on the back side from the bottom of the grooves, and a plurality of lap cell parts separated from each other by the grooves. The lap platen is characterized in that the lap cell portion is provided with means for making the temperature distribution in the thickness direction of the base plate portion substantially uniform.

Function: The temperature distribution in the thickness direction of the base plate portion becomes almost uniform, and the temperature difference becomes small, so that thermal deformation becomes small.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to FIGS. 4 to 11. In addition, in these drawings, Figures 1 to 3
The same reference numerals are given to the parts corresponding to those of the conventional example in the figure.

4 and 5 show a first embodiment.

In the case of the first embodiment, the groove depth d is, for example, about three times deeper than that of the conventional one.

Since the ratio (d/B) between the groove depth d and the wrap cell part width B is large, the amount of heat q mainly flows in the direction of the side surface (15) of the wrap cell part (14), as shown in FIG. therefore,
Heat is prevented from flowing into the base plate portion (13), the temperature distribution in the thickness direction of the base plate portion (13) becomes substantially uniform, and no thermal deformation occurs in the base plate portion (13). In addition, the wrap cell portion (14) has an axially symmetrical temperature distribution, and a temperature difference occurs; however, the wrap cell portion (14)
) are separated by grooves (11), and the wrap cell width B is smaller than the diameter of the lap surface plate, so deformation of the wrap cell portion (14) can be ignored. Therefore, thermal deformation of the lapped surface (lO) is very small.

6 and 7 show a second embodiment.

In the case of the second embodiment, the entire circumference of the fourth side of about half of the back side of the wrap cell part (14) is removed, and the guide pillar part (14) having a width smaller than the width B of the wrap surface (IO) part ( 1B) is formed.

As shown in FIG. 7, the amount of heat q is
The heat is dissipated by the back surface (17) of the portion on the lap surface (lO) side and the side surface (18) of the guide column part (1B), and the amount of heat conducted into the base plate part (13) is close to O. 13) The temperature distribution in the thickness direction becomes almost uniform. Therefore, the thermal deformation of the lapped surface (lO) will be very small as well.

FIGS. 8 and 9 show a third embodiment.

The lapping surface plate of the third embodiment is used, for example, as a polishing plate, and has a plurality of holes (19) that intersect with each other formed approximately in the center in the thickness direction using a gun drill or the like.

Further, on the front and back sides of these holes (19), a plurality of grooves (11) and (20) orthogonal to each other are formed by wire cutting or the like. The portion between the grooves (11) on the front side is a wrap cell portion (14), and the portion on the back side thereof is a base plate portion (13). In addition, the groove (
11), the hole (19) and the groove (11) (
The end portion of 20) is sealed with a seal (21) made of a soft elastic member such as silicone rubber. A water cooling jacket (22) is fixed to the back surface (12) of the lap surface plate, and grooves (23) are formed on the surface side thereof corresponding to the grooves (20) of the lap surface plate. And the groove (23) of the jacket (22), the wrap, and the hole of the surface plate (19)
Cooling water is circulated through the grooves (11) and (20). Further, a polishing pad (24) is attached to the lapping surface (lO) side of the lapping surface plate.

A hole (19) is formed between the base plate part (13) and the wrap cell part (14), and cooling water is flowing through this hole (19), so the amount of heat q is (
19) and is not transmitted to the base plate portion (13). Therefore, the temperature distribution of the base plate part (13) becomes almost uniform, and similarly, the temperature distribution of the base plate part (13) becomes almost uniform.
The thermal deformation of will be very small.

FIG. 10 and FIG. 11 show a fourth embodiment.

In the case of the fourth embodiment, a heat insulating layer (25) is provided between the wrap cell section (14) and the base plate section (13). That is, the wrap cell part (14) is divided into two parts on the base plate part (I3) side, and the heat insulating layer (25)
) are bonded together using an epoxy resin adhesive that has a heat insulating effect. Then, the base plate part (1
3) is a known low-expansion material, and the wrap cell portion (I4) is made of a relatively inexpensive material similar to the conventional material.

Since the heat insulating layer (25) is provided between the wrap cell section (14) and the base plate section (13), the amount of heat transmitted to the base plate section (13) is small, as shown in FIG. The temperature gradient in the thickness direction becomes smaller. Furthermore, since the base plate portion (13) is made of a low-expansion material, thermal deformation is extremely small.

In order to reduce thermal deformation of the lap surface plate, it is possible to make the entire plate from a low expansion material, but low expansion materials are very expensive. In the case of the fourth embodiment, only the base plate portion (13) is made of a low-expansion material, so it is cheaper than the case where the entire base plate part (13) is made of a low-expansion material.

In addition, when the wrap cell part (14) wears out, it is only necessary to replace the wrap cell part (14), and the base plate part (13) made of expensive low expansion material can be used continuously, reducing the cost of the lap surface plate. It is possible.

Effects of the Invention According to the lap surface plate of the present invention, as described above, the temperature distribution in the thickness direction of the base plate portion becomes almost uniform,
Since the temperature difference becomes smaller, thermal deformation becomes smaller.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a conventional lap surface plate, Figure 2 is a partially cutaway perspective view showing an enlarged main part of the lap plate shown in Figure 1, and Figure 3 is a wrap plate shown in Figure 2. An explanatory diagram showing the movement of heat and temperature distribution of the surface plate, Fig. 4 is a drawing equivalent to Fig. 2 showing the first embodiment, Fig. 5 is a drawing equivalent to Fig. 3, and Fig. 6 is a drawing equivalent to Fig. 2.
7 is a drawing equivalent to FIG. 2 showing the embodiment, FIG. 7 is a drawing corresponding to FIG. 3 F, FIG. 8 is a drawing equivalent to FIG. 2 showing the third embodiment, and FIG. 9 is a drawing equivalent to FIG. 10 is a drawing corresponding to FIG. 2 showing the fourth embodiment, and FIG. 11 is a drawing corresponding to FIG. 3. (lO) ... Wrap surface, (11) ... Groove, (12
)... Back side, (13)... Base plate part, (1
4) ... Wrap cell part, (IB) ... Guide column part, (1
9)...hole, (25)...insulating layer. Patent applicant: Hitachi Zosen Metal Works Co., Ltd. Agent Einosuke Atsugi (4 others)]1

Claims (1)

[Claims] In a lap surface plate in which a plurality of grooves that intersect with each other are formed on the surface and is divided into a base plate portion on the back side from the bottom of the grooves and a plurality of wrap cell portions separated from each other by the grooves, the wrap cell portion includes: A lap surface plate characterized by being provided with means for making the temperature distribution substantially uniform in the thickness direction of the base plate portion.