JPH03270048A - Vacuum chuck - Google Patents

Abstract

PURPOSE:To attract and fix even a large-diameter wafer having large warpage with excellent positional accuracy by forming a housing recessed section to one part of a wafer base with a plane-shaped wafer straightening surface and mounting an elastically deformable attraction pad into the recessed section while connecting paths connecting the inside of a skirt section to vacuum sources are formed to the wafer base and the attraction pad. CONSTITUTION:When a wafer 8 is placed onto a wafer base 1, the skirt sections 7a of an attraction pad 7 are elastically deformed under the state in which the skirt sections 7a are fast stuck while following the warpage of the rear of the wafer 8 by the weight of the wafer 8 because the skirt sections 7a are projected to sections higher than a wafer straightening surface 5. When the insides of the skirt blocks 7a are decompressed by a vacuum source beta under the state, the skirt sections 7a are shrunk up to positions as the same surfaces as the wafer straightening surface 5 of the wafer base 1, and the wafer 8 is attracted to the wafer straightening surface 5 and straightened up to the state of approximately a plane while following the straightening surface 5. When a vacuum source alpha is operated under the state, space formed by a sintered metallic material 3 and the wafer 8 is decompressed through the metallic material 3, and the wafer 8 is attracted to the sintered metallic material 3 and straightened completely under the state of the plane and fixed.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a vacuum chuck that suctions and fixes semiconductor wafers using the pressure difference with the atmosphere, and provides a vacuum chuck that can suction and fix even large-diameter wafers with large warpage with high positional accuracy. With the purpose of is provided with a suction pad having a skirt portion that can be elastically deformed from a position protruding beyond the wafer straightening surface to a position flush with the wafer straightening surface, and the interior of the skirt portion is evacuated on the wafer stand and suction pad. It was constructed by providing a communication path connected to the source.

[Industrial Application Field] The present invention relates to a vacuum chuck that suctions and fixes a semiconductor wafer by utilizing a pressure difference with the atmosphere.

In recent years, with the progress of larger diameter semiconductor wafers and finer patterns in the integrated circuit manufacturing process, in the field of manufacturing equipment, mechanisms that can chuck large-diameter wafers (e.g. 8 inches or more) with large warpage with high positional accuracy are needed. is required.

For this reason, vacuum chucks are often used as a relatively convenient method to prevent misalignment of wafers during wafer processing.

[Prior Art] A conventional vacuum chuck is shown in FIGS. 6 and 7. The wafer stand IO has a planar wafer straightening surface 11, and a suction passage 12 connected to a vacuum source is formed in the center thereof. The suction passage 12 is provided in the wafer correction surface 11.
A plurality of grooves 13 are carved concentrically with the grooves 13.
is connected to the suction passage 12 via a connecting groove 14. Further, an elastic body 15 made of vinyl chloride or the like is adhered to the surface of the wafer straightening surface 11 so that the chuck portion follows the warp of the wafer 16 when the wafer 16 is sucked. Then, the wafer 1 is
The space formed by the back surface of the wafer X16 and the wafer straightening surface 11 is depressurized, and the wafer X16 is suctioned and fixed.

Another vacuum chuck is one in which a highly elastic rubber pad is attached to a flat base material.

[Problems to be Solved by the Invention] However, each wafer has its own warpage depending on the pattern formed, and in particular, the warpage of a large-diameter wafer is significantly larger than that of a small-diameter wafer. Therefore, in the conventional vacuum chuck in which the elastic body 15 is attached to the surface of the wafer straightening surface 11, there is a problem that the chuck part does not follow the warp of the wafer 16, and the wafer 16 cannot be suctioned. .

Further, in the case of using a rubber pad, there is a problem that when the wafer is placed vertically during transportation and an external force such as gravity is applied, the rubber pad is easily deformed and misaligned.

The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a vacuum chuck that can suction and fix even large-diameter wafers with large warpage with good positional accuracy.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a vacuum chuck that sucks and fixes a semiconductor wafer by utilizing a pressure difference with the atmosphere, and a wafer table having a flat wafer straightening surface. An accommodating recess is formed in the accommodating recess, and within the accommodating recess is provided a suction pad having a skirt portion that can be elastically deformed from a position protruding beyond the wafer straightening surface to a position flush with the wafer straightening surface. A communication path connecting the inside of the skirt portion to a vacuum source was provided in the wafer stand and suction pad.

[Function] When a semiconductor wafer is suctioned and fixed, the skirt protrudes beyond the wafer straightening surface of the wafer stand, so even if the wafer is highly warped, the skirt follows the back surface of the wafer and remains in close contact due to the weight of the evaporator. It transforms with. In this state, when the inside of the skirt part is depressurized, the skirt part contracts to a position where it is almost flush with the wafer straightening surface and attracts the wafer to the wafer straightening surface. As a result, the wafer is straightened into a flat surface following the wafer straightening surface and fixed by suction.

[Example] An example embodying the present invention will be described below with reference to FIGS. 1 to 5.

As shown in FIG. 1, the wafer stand l has a circular shape and is composed of a base material 2 having an outer peripheral flange 2a, and a porous sintered metal material 3 fitted and fixed to the base material 2. As shown in FIG. 2, the base material 2 is formed with a through hole 2b corresponding to the sintered metal material 3 and connected to the vacuum source α.

The base material 2 has a plurality of annular shapes spaced at equal angular intervals (
In this embodiment, four convex portions 4 are formed, and each convex portion 4 is exposed from a through hole 3a formed in the sintered metal material 3, as shown in FIG. And the outer peripheral flange 2a
, the surface of the sintered metal material 3 , and the end surface of the convex portion 4 are formed flush with each other, and these form a planar wafer straightening surface 5 .

As shown in FIG. 2, a circular housing recess 6 is formed in each of the convex portions 4, and a suction pad 7 made of an elastic material such as rubber is attached within the housing recess 6. As shown in FIG. 3, the skirt portion 7a on the upper part of the suction pad 7 projects above the wafer straightening surface 5. In addition, a communication path is constituted by the through hole 7b formed in the center of the suction pad 7 and the path 2c formed in the base material 2, and the through hole 7b
The inside of the skirt portion 7a and the vacuum source β are connected by the passage 2c.

Next, the operation of the vacuum chuck configured as described above will be explained.

Each semiconductor wafer 8 has its own warpage due to the pattern formed in the manufacturing process, and the warpage is particularly large in large diameter wafers.

When suctioning and fixing the warped semiconductor wafer 8 in this way, the wafer 8 is placed on the wafer stand 1 as shown in FIGS.
When placed on the top, the skirt portion 7a of the suction nozzle 7 protrudes above the straightening surface 5, so the skirt portion 7a follows the warp of the back surface of the wafer 8 due to the weight of the wafer 8 and adheres tightly. It deforms elastically in this state.

In this state, when the inside of the skirt part 7a is depressurized by the vacuum source β, the skirt part 7a contracts to a position where it is flush with the wafer straightening surface 5 of the wafer stand 1, as shown in FIG. Attracted to surface 5. As a result, the wafer 8 is straightened to a substantially flat state following the wafer straightening surface 5.

In this state, the wafer 8 is very close to the sintered metal material 3, and when the vacuum source α shown in FIG. The pressure in the space formed by the wafer 8 is reduced, and the wafer 8 is attracted to the sintered metal material 3, completely straightened into a flat state, and fixed.

As described above, in this embodiment, the end face of the outer circumferential flange 2a of the base material 2, the surface of the sintered metal material 3, and the end face of the convex portion 4 constitute a planar wafer straightening surface 5, and the accommodating recess of the wafer table 1 Since the suction pad 7 is mounted in the wafer 6 so that the skirt portion 7a projects above the wafer straightening surface 5, even large diameter wafers with large warpage can be suctioned. or,
When the pressure inside the skirt portion 7a is reduced, the skirt portion 7a contracts to a position where it is flush with the wafer straightening surface 5, and the wafer 8
The wafer 8 is attracted to the wafer straightening surface 5 and straightened to a nearly flat state, so even if an external force such as gravity or centrifugal force acts, the wafer 8 is straightened by the frictional force between the wafer 8 and the wafer straightening surface 5.
can be chucked with high positional accuracy.

Further, in this embodiment, the wafer stand 1 is constructed of a porous sintered metal material 3, and this sintered metal material 3 is connected to a vacuum source α through a through hole 2b formed in the base material 2. , the wafer 8 can be completely straightened into a flat state and fixed by suction more reliably.

Although the vacuum source α and the vacuum source β are provided separately in this embodiment, they may be the same vacuum source.

Further, although four suction pads 7 are provided in this embodiment, an arbitrary number of suction pads may be provided.

[Effects of the Invention] As detailed above, according to the present invention, even large-diameter wafers with large warpage can be suctioned and fixed with good positional accuracy.

[Brief explanation of drawings]

1 is a plan view showing a vacuum chuck according to an embodiment of the present invention; FIG. 2 is a cross-sectional view taken along the line A-A in FIG. 1; FIG. 3 is an enlarged cross-sectional view of main parts; FIG. 5 is an enlarged cross-sectional view of a main part for explaining the operation, FIG. 6 is a plan view showing a conventional vacuum chuck, and FIG. 7 is a cross-sectional view of a conventional vacuum chuck. In the figure, l is a wafer stand, 2c is a passage forming a communication path, 5 is a wafer straightening surface, 6 is a storage recess, 7 is a suction pad, 7a is a skirt portion, 7b is a through hole forming a communication path, 8 is a through hole forming a communication path. It is a semiconductor wafer.

Claims (1)

[Claims] In a vacuum chuck that sucks and fixes a semiconductor wafer (8) using a pressure difference with the atmosphere, a housing recess (6) is provided in a part of a wafer stand (1) having a flat wafer straightening surface (5).
), and a skirt portion (7a) that can be elastically deformed from a position protruding beyond the wafer straightening surface (5) to a position flush with the wafer straightening surface (5) is formed in the accommodation recess (6). A suction pad (7) is provided, and a communication path (2c, 7b) is provided in the wafer stand (1) and the suction pad (7) to connect the inside of the skirt portion (7a) to a vacuum source. vacuum chuck.