JPH05218182A - Wafer supporter device - Google Patents

Abstract

PURPOSE:To provide a wafer supporter device capable of horizontally supporting a large diameter wafer without deformation of the same. CONSTITUTION:There is provided a liquid reservoir 14 for storing a specific gravity fluid 12 having a predetermined specific gravity nearly equal to the specific gravity of a wafer 10. Once the wafer 10 is placed on the surface of the specific gravity fluid 12. the wafer 10 rests horizontally in a flowting state when there are balanced the self weight thereof and the floating force of the specific gravity fluid 10. More specifically, since the wafer 10 is rendered to the floating force directed vertically upwardly by the specific gravity fluid 12 over the entire bottom surface thereof, even the large diameter wafer 10 can horizontally be supported without being deformed downward at the center thereof. Hereby, the surface state of the wafer 10 can accurately be measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer supporting device,
In particular, the present invention relates to a wafer supporting device used when inspecting the surface shape of a semiconductor wafer.

[0002]

2. Description of the Related Art In a conventional wafer supporting apparatus of this type, a semiconductor wafer 4 is placed on three supporting fulcrums 1, 2, 3 as shown in FIG. That is, a wafer support device is used which utilizes the formation of one ideal flat surface for connecting three points.

[0003]

However, as the diameter of the semiconductor wafer is increased, the conventional wafer supporting apparatus is supported at three points, so that the central portion of the wafer is bent downward due to the weight of the wafer and the surface shape of the wafer is reduced. Is difficult to measure accurately. The present invention has been made in view of such circumstances, and an object of the present invention is to provide a wafer support device capable of horizontally supporting a large-diameter wafer without bending.

[0004]

In order to achieve the above object, the present invention stores a specific gravity liquid having a specific gravity close to that of a semiconductor wafer in a liquid tank, and the semiconductor wafer is placed on the specific gravity liquid. Characterized by supporting

[0005]

According to the present invention, when a liquid tank storing a specific gravity liquid having a specific gravity close to that of a semiconductor wafer is provided and the wafer is placed on the surface of the specific gravity liquid, the weight of the wafer and the buoyancy of the specific gravity liquid are increased. Can be balanced and can be left stationary horizontally. This is because the entire bottom surface of the wafer is uniformly subjected to the vertically upward buoyancy force from the specific gravity liquid, which allows the wafer to be placed on a horizontal flat surface.

As a result, even in the case of a large-diameter wafer, by supporting it in a state of floating in the specific gravity liquid, the central portion of the wafer does not bend downward.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of a wafer supporting apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. In FIG. 1, a liquid tank 14 storing silicon oil 12 having the same specific gravity as that of the semiconductor wafer 10 is provided. Also,
The polyethylene thin film 16 is in contact with the entire liquid surface of the silicone oil 12. Moreover, when the wafer 10 is placed on the thin film 16, the thin film 16 receives the buoyancy force from the silicon oil 12 without being interfered with by the thin film 16, and the wafer 10 may be naturally floated on the side surface of the liquid tank 14 with a margin. It is fixed to the fixing member 18 provided.

The wafer 1 is provided above the liquid tank 14.
Light source device 20 and light receiving device 22 for inspecting the surface state of 0
Is provided. The operation of such a wafer supporting device will be described. A wafer 10 cut by a wafer slicing machine (not shown) is placed at the center of the thin film 16 that is in contact with the silicon oil 12. Due to its own weight, the wafer 10 passes through the thin film 16 and the silicon oil 1
I try to sink into 2. However, when the weight of the wafer 10 and the buoyancy of the silicon oil 12 are in balance, the wafer 10 floats on the silicon oil 12 through the thin film 16 and stands horizontally.

This is because the buoyancy, which is equal to the weight of the silicon oil 12 deposited on the wafer 10, acts evenly vertically upward on the entire bottom surface of the wafer 10. This allows
Even with a large-diameter wafer, the central portion of the large-diameter wafer, which is a drawback of the conventional wafer supporting apparatus, does not bend downward. Also, by contacting the thin film with the silicone oil surface,
It is possible to prevent the wafer from being unbalanced and sinking in the silicon oil due to vibration and the like, and also to prevent the wafer from being contaminated with the solution.

When the surface shape of the wafer 10 supported by the silicon oil 12 is to be examined in this way, for example, the light source device 20 irradiates the upper surface of the wafer 10 on the atmosphere side with a light beam,
The reflected light reflected is received by the light receiving device 22, and the state of the interference fringe is measured. If the surface of the wafer 10 is completely flat, linear interference fringes arranged at equal intervals can be obtained.
If the surface of 0 is warped, the interference fringes are not evenly spaced and are not linear, so that the state of the wafer fringe can be known by measuring the state of the interference fringes.

In this case, it is necessary that the wafer 10 is always supported horizontally, and if the wafer supporting apparatus of the present invention is used, the wafer 10 is always supported horizontally, so that the state of the surface of the wafer 10 is maintained. Can be measured accurately.
Although silicon oil was used as the specific gravity liquid in this example, the specific gravity is not limited to silicon oil, and for example, the specific gravity of the wafer such as a solution of sucrose in water is close to that of the wafer, and the wafer has a specific gravity of floating. Any fluid may be used. Also,
The specific gravity liquid is not limited to a single fluid, but a solute may be dissolved in a solvent to prepare a specific gravity liquid having a desired specific gravity.

Although the thin film made of polyethylene is used in this embodiment, the thin film is not limited to polyethylene, and when the wafer is placed on the thin film as described above, the wafer is not interfered with by the thin film. It is sufficient that the thin film has elasticity so that it naturally floats by receiving the buoyancy force from the specific gravity liquid, or when the thin film is fixed to the liquid tank, the thin film is not strained and has a margin.

Although the interferometer is used for measuring the surface of the wafer in this embodiment, the method is not particularly limited to this method, and any non-contact type sensor such as a capacitance sensor may be used.

[0014]

As described above, according to the wafer supporting apparatus of the present invention, the liquid tank for storing the specific gravity liquid having a specific gravity close to that of the semiconductor wafer is provided, and the wafer floats in the specific gravity liquid in the previous period. Therefore, when the weight of the wafer is balanced with the buoyancy of the specific gravity liquid, the wafer is horizontally supported in a floating state. That is, the wafer receives the buoyancy vertically upward from the specific gravity liquid evenly on the entire bottom surface of the wafer.

As a result, even in the case of a large-diameter wafer, the central portion of the wafer does not bend downward, and the state of the wafer surface can be accurately measured.

[Brief description of drawings]

FIG. 1 is an explanatory view of a wafer supporting apparatus according to the present invention.

FIG. 2 is an explanatory view of a conventional wafer supporting device.

[Explanation of symbols]

 10 ... Wafer 12 ... Silicon oil 14 ... Liquid tank 16 ... Thin film

Claims (2)

[Claims] 1. A wafer supporting apparatus characterized in that a specific gravity liquid having a specific gravity close to that of a semiconductor wafer is stored in a liquid tank, and the semiconductor wafer is supported on the specific gravity liquid. 2. The wafer supporting device according to claim 1, wherein the semiconductor wafer is supported on a thin film which is in contact with the entire liquid surface of the specific gravity liquid stored in the previous liquid tank.