JPS6276146A - Thermal conductor for ionic processing device - Google Patents

Abstract

PURPOSE:To more heighten the thermal conduction between a target material such as a wafer and a support therefore, by filling a silicone rubber in the communicating pores of the surface portion of a porous metal body having a three-dimensionally reticulate construction and numerous communicating pores. CONSTITUTION:A silicone rubber 22 is filled in the commnicating pores of at least the surface portion of a plate-shaped porous metal body 20 having a three-dimensionally reticulate construction 201 and numerous communicating pores 202. As a result, the thermal conductivity of a thermal conductor consisting of the metal body 20 and the silicone rubber 22 is made at least 10 times higher than that of a sheet consisting of a silicone rubber and boron nitride mixed therein. Since the porous metal body 20 performs a buffer action and the silicone rubber 22 filled in the surface portion of the metal body is elastic, the contact area (which is an important factor as well as the thermal conductivity) of the thermal conductor on a target material such as a wafer 12 can be made large.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to ion processing equipment such as ion implantation WF', ion evaporation thin film forming equipment that uses both ion implantation and vacuum evaporation, and ion beam etching equipment. The present invention relates to a thermal conductor that conducts heat between a target material such as a wafer and its support.

[Conventional technology]

When a wafer is irradiated with an ion beam in a vacuum in an ion implanter or the like, the temperature of the wafer becomes extremely high.

For example, in a 200KV, 1mA ion implanter, the energy injected into the wafer is 200KV.
X'l (mA) = 200 [W], and since the atmosphere is a vacuum, the temperature of the wafer rises to several hundred degrees Celsius to balance the heat dissipation due to radiation.

In order to prevent this, a wafer holder 2 as shown in FIG. 3, for example, has conventionally been used. This wafer holder 2 is used, for example, in a production type ion implantation device, and includes a support body (also called a cooling platen or a cooling backing plate) 4 (not shown in the figure) with a slightly convex central portion of the upper surface. A thermal conductor 8 made of silicone rubber is installed on the upper surface, and a wafer (for example, a silicon wafer) 12 is pressed onto the thermal conductor 8 by a wafer holder 10.The thermal conductor 8 supports the heat of the wafer 12. It is transmitted to the body 4 and cooled. Note that 6 is a passage through which a cooling medium such as cooling water passes, and 14 is the aforementioned ion beam.

In that case, silicone rubber is used as the thermal conductor 8 because silicone rubber has elasticity, and when the wafer 12 is pressed, the silicone rubber deforms and the wafer 12
This is because the contact area is expanded by closely adhering to the support 4, thereby improving thermal conductivity. Moreover, the reason why the center part of the upper surface of the support body 4 is made slightly convex is because when the wafer holder 10 presses the periphery of the wafer 12, a load is also applied to the center part of the wafer 12, so that the entire wafer 12 is cooled uniformly. This is to ensure that.

(Problem to be solved by the invention) However, since the silicone rubber used as the thermal conductor 8 has low thermal conductivity, the above-mentioned problems occur despite the above-mentioned efforts. Conventionally, it has been impossible to suppress the temperature of the wafer 12 under implantation conditions to about 100° C. or less.

Therefore, it is an object of the present invention to provide a thermal conductor that can be used, for example, in the above-mentioned locations, and can further improve heat conduction between a target material such as Ueno and its support. purpose.

[Means for solving problems]

The thermal conductor of the present invention is characterized in that it is formed by filling silicone rubber into the communicating pores in at least the surface layer of a metal porous body having a three-dimensional mesh-like skeleton and a large number of communicating pores.

(Function) In the metal porous body, both the skeleton and the filled silicone rubber are a three-dimensional continuum, and its thermal conductivity reaches approximately 50% of that of the metal itself.The metal porous body also has a cushioning effect. Furthermore, since the silicone rubber filled in the surface layer has elasticity, the contact area with the target material such as a wafer can be increased.Therefore, this thermal conductor can be used to connect the target material such as a wafer and its support. Heat conduction between the two is further improved.

〔Example〕

FIG. 1 is a schematic side view showing a thermal conductor according to an embodiment of the present invention, and FIG. 2 is an enlarged side view of section A in FIG. The thermal conductor 18 according to this embodiment is used in place of the thermal conductor 8 of the wafer holder 2 as described above, for example, and has a skeleton 201 in the form of a three-dimensional mesh and a large number of communicating holes 202. A plate-shaped porous metal body 20 having
Silicone rubber 22 is filled in the communicating holes 202 in at least the surface layer of the holder.

In the metal porous body 20, both the metal skeleton 201 and the silicone rubber 22 filled in the communicating holes 202 are three-dimensional continuums, and their thermal conductivity is approximately 50% of the value of the metal itself. For example, it exhibits a thermal conductivity that is 10 times or more higher than that of a BN-containing sheet in which boron nitride is mixed into silicone rubber, which has been commonly used in the past.

Regarding the contact area, which is an important factor along with thermal conductivity, the metal porous body 20 has a cushioning effect, and the silicone rubber 22 filled in the surface layer of the metal porous body 20 also has a cushioning effect.
Since the material has elasticity, the contact area with the target material such as the wafer 12 (see FIG. 3) can be increased.

In that case, the silicone rubber 22 may also cover the surface of the metal porous body 20 on which the wafer 12 is pressed. It is preferable to have a structure in which the wafer 12 is pressed against the surface of the wafer 20 and protrudes like a protrusion. In this way, when the wafer 12 is warped, each protrusion expands and contracts, and the contact with the wafer 12 is distributed over the entire surface of the wafer 12, making it uniform. This is because it becomes easier to perform the same procedure.

In this case, the height H of the protrusion of the silicone rubber 22 should be such that it can expand and contract to accommodate the expected warpage of the wafer 12, for example, at least 2 to 3 times the warp.

Furthermore, although the silicone rubber 22 may be completely filled in the entire inside of the metal porous body 20, it is rather contained in the communicating holes 202 in the surface layer portion (for example, depth D) of the metal porous body 20, as shown in FIG. It is preferable to fill only the This is because once the heat is transferred to the metal skeleton 201, the skeleton 201 becomes the main heat conduction means. Therefore, the silicone rubber 22 is spread only to the depth necessary to conduct heat from the silicone rubber 22 to the skeleton 20. It is enough if it is filled,
This is also because a space is created below the silicone rubber 22 in which the silicone rubber 22 can expand and contract, increasing the expansion and contraction rate of the silicone rubber 22, and making contact with the sea urchin fly 2 even better.

As the metal porous body 20, for example, Selumenoto (trade name) manufactured by Sumitomo Electric Industries, Ltd. can be used. The cell membrane is made of Ni or Ni-Cr, and can have a porosity (ie, the ratio of pore volume to unit volume) of up to 98%.

However, the porosity of the metal porous body 20 is preferably in the range of 90 to 98%, particularly preferably in the range of 94 to 97%.

This is because when the porosity is less than 90%, the cushioning effect of the metal porous body 20 is small and the flexibility is reduced, resulting in poor contact with the wafer 12. When the porosity exceeds 98%, the three-dimensional continuous network structure This is because the skeleton 201 is no longer formed. In particular, a three-dimensional network porous structure is formed and the cushioning effect is good when the porosity is in the range of 94 to 97%. The silicone rubber 22 filled in the communicating holes 202 of the porous metal body 20 also acts to enhance the cushioning effect of the porous metal body 20.

In the thermal conductor 18 as described above, thermal conduction between a target material such as a wafer and its support is further improved compared to silicone rubber or the like. For example, when the thermal conductor 18 as described above is used as the thermal conductor 8 of the wafer holder 2 as shown in FIG. 3, and ion implantation is performed at 200 KV x 1 mA, for example, the temperature of the wafer 12 is lowered to about 90°C. becomes possible.

The thermal conductor 18 as described above can also be used in a wafer holder other than the wafer holder 2 illustrated above, or between a disk and a wafer in a batch type apparatus. Furthermore, the thermal conductor 18 is not limited to the ion implantation equipment as exemplified above, but can be widely used for cooling target materials such as wafers in the ion processing equipment as exemplified first. Of course.

〔Effect of the invention〕

As described above, according to the present invention, thermal conductivity between a target material such as a wafer and its support is further improved.

[Brief explanation of drawings]

FIG. 1 is a schematic side view showing a thermal conductor according to an embodiment of the present invention. FIG. 2 is an enlarged side view of section A in FIG. 1. FIG. 3 is a cross-sectional view showing an example of a wafer holder of an ion implantation device.

Claims (1)

[Claims] (1) Heat conduction for an ion processing device characterized by filling silicone rubber into the communicating pores in at least the surface layer of a metal porous body having a three-dimensional mesh-like skeleton and a large number of communicating pores. body.