JP2720405B2 - Wafer fixing disk - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] A disk that presses and fixes the periphery of a semiconductor wafer in a state where a resist is applied to the surface of the semiconductor wafer. , A pressing surface for pressing the periphery of the wafer in an annular shape from above, and a light scattering uneven surface on the edge forming the window.

[Industrial applications]

The present invention relates to a disk for fixing a wafer, and more particularly to a disk for pressing and fixing the periphery of a semiconductor wafer in a state where a resist is applied to the surface of the semiconductor wafer.

[Conventional technology]

When patterning a film formed on the surface of a semiconductor wafer, apply a resist on the film to be patterned,
An exposure mask is placed thereon to expose the resist, and then the resist is developed to form a resist mask. Thereafter, the patterning film is etched to transfer the pattern formed on the resist mass 7 to the patterning film.

By the way, when the film to be patterned on the semiconductor wafer is etched by the reactive ion etching method, the etchant easily enters from the side of the semiconductor wafer, so that the etching rate around the semiconductor wafer increases, and the pattern becomes narrower than the inside. There was such a problem.

In order to solve this problem, the present applicant has disclosed in
In Japanese Patent No. 6230 (FIG. 5 of the present application), when exposing the resist 52, the periphery of the semiconductor wafer 50 is covered with a disk 51 (FIG. 5 (b)). A method is proposed in which the etchant is left behind (FIG. 10C) and the etchant is prevented from entering from the side by the peripheral resist 52 (FIG. 10D).

[Problems to be solved by the invention]

By the way, FIG. 5 (a), (b)
Window to expose the pattern formation area as shown in
The window 53 has a shape of a semiconductor wafer 50.
In addition to having a straight portion t and a curved portion s, the surface of the side portion 54 of the window 53 is formed flat. here,
The straight line portion t is a portion corresponding to the orientation flat.

For this reason, the light reflected from the side portion 54 at the time of exposure causes interference in the region u near the intersection of the straight line portion t and the curved portion s to increase the amount of exposure, causing local overexposure. It causes pattern defects.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a wafer fixing disk capable of uniformly performing exposure.

[Means for solving the problem]

As described above, as shown in FIG. 1, a window 2 for exposing a pattern forming region on a surface of a wafer W coated with a resist R, a pressing surface 3 for pressing the periphery of the wafer W in an annular shape from above, The problem is solved by a wafer fixing disk characterized by having an uneven surface for light scattering provided on the edge 4 of the window 2.

(Operation)

According to the present invention, an uneven surface is formed on the inner edge 4 of the window 2 provided on the wafer fixing disk 1.

Therefore, at the edge 4 of the window 2 of the disk 1, the light for exposure is scattered by the uneven surface for light absorption.
In the vicinity of the intersection between the linear portion 7 and the curved portion 8 of the window 2, the exposure amount does not increase due to light interference, and the light that has passed through the exposure mask 9 irradiates the entire resist R as it is to make the exposure uniform. It is possible to do. Moreover, disk 1
When the positive resist R applied to the wafer W is exposed in a state where the wafer W is held down, the resist R around the wafer W is unexposed in a strip shape.

Therefore, when the wafer fixing disk of the present invention is used, not only can the etching be made uniform, but also there is no overexposure, and the resist can be uniformly exposed.

〔Example〕

Therefore, an embodiment of the present invention will be described below with reference to the drawings.

1 and 2 are a plan view and a partially enlarged cross-sectional view of an apparatus showing an embodiment of the present invention.
A window 2 for exposing a pattern formation region at the center of the semiconductor wafer W is formed in the center of the disk 1 in substantially the same shape as the semiconductor wafer W. In the outer bottom of 2,
A pressing surface 3 that covers the periphery of the semiconductor wafer W in a band shape is formed.

Further, the inner edge portion 4 forming the window 2 of the disk 1 is formed substantially perpendicular to the bottom surface of the disk 1 and has an uneven surface, and absorbs light hitting the inner edge portion 4. It is configured to be.

Numeral 5 is a mat made of an elastic material formed in an annular shape and formed to have a thickness substantially equal to that of the semiconductor wafer W. In the center thereof, a wafer storage portion 6 for storing the semiconductor wafer W is provided. The configuration is such that the disk 1 is placed with the wafer W stored in the unit 6.

In the drawing, reference symbol F denotes an orientation flat of the semiconductor wafer W, and 7 denotes an orientation flat F.
, 8 is a curved portion of the window 2, and 9 is a curved portion of the window 2.
The exposure mask, M, indicates a film to be patterned formed on the semiconductor wafer.

Next, the operation of the above embodiment will be described with reference to FIG.

In the above-described embodiment, first, as shown in FIG. 2A, a resist R is applied on a patterning target film M formed on a semiconductor wafer W, and then the semiconductor wafer W
Is placed in the wafer accommodating portion 6 of the mat 5, the disk 1 is placed thereon, and the semiconductor wafer W is pressed by the pressing surface 3.

In this case, the disk 1 is placed so as to expose the pattern formation region at the center of the semiconductor wafer W from the window 2 and to cover the periphery of the semiconductor wafer W which does not hinder the pattern formation in an annular shape.

Then, the exposure mask 9 is placed above the semiconductor wafer W, and when ultraviolet light is irradiated from above, the pattern of the exposure mask 9 is transferred to the resist R formed on the semiconductor wafer W, and the latent image Is formed. In this case, a band-shaped unexposed area is formed around the semiconductor wafer W.

By the way, when the resist R is exposed, the inner edge 4 of the disk 1 forming the window 2 is slightly irradiated with ultraviolet light, but the surface of the inner edge 4 is formed in an uneven shape and scatters light. As a result, the amount of light reflected toward the semiconductor wafer W becomes extremely small.

Therefore, the light reflected from the surface of the inner edge portion 4 near the intersection of the linear portion 7 and the curved portion 8 of the window 2 does not interfere with the irradiation of the resist R, and irradiates the resist R with uniform ultraviolet light. Exposure.

After the above exposure process is completed, the resist R is developed to form a pattern as shown in FIG.
Next, the film to be etched M is etched by a reactive ion etching method using the pattern transferred to the resist R as a mask (FIG. 2). A chlorine-based gas is used as an etching gas.

According to this etching, the strip-shaped resist R remaining around the semiconductor wafer W prevents the etchant from excessively penetrating from the side, and as a result, the film M to be etched is uniformly etched. Will be.

Therefore, if the wafer fixing disk 1 of the present embodiment is used, there is no portion where the overexposure occurs, so that the etching and the resist exposure can be made uniform.

Here, a description will be given of a measurement result obtained by comparing the present embodiment with the conventional example.

FIG. 3 is a characteristic diagram showing an exposure state near an intersection between the straight line portion 7 and the curved portion 8 of the window 2 in comparison with a conventional case.

In this case, the exposure is performed shallowly in a short time 0.37 times shorter than the normal exposure time without using the exposure mask 9. Then, as shown in FIG. 3 (b), the resist R is developed after the exposure, and the region near the intersection of the straight line portion 7 and the curved line portion 8 is centered at every 1 mm with the unexposed region as a starting point (i). Looking at the development state at eight locations toward.

According to this measurement result, according to the present invention, as shown by a solid line in the drawing, the resist R
According to the conventional method shown by the broken line, the thickness of the resist R in the step (iv) is further reduced by about 0.5 μm, and it is confirmed that overexposure has occurred. ing.

The reason is that the surface of the edge 4 of the window 2 is flat in the prior art, whereas the surface of the inner edge 4 is uneven in the present invention so that light is scattered by the surface. According to the present invention, there is no overexposed portion due to light interference near the intersection of the linear portion 7 and the curved portion 8 of the window 2. When developing the resist R, the constraint by the disk 1 is released.

In the above-described embodiment, the inner edge 4 forming the window 2 of the disk 1 is formed in the vertical direction. However, as shown in FIG. 4, the inner edge 14 is formed in a tapered shape, and the inner surface and the tapered surface are formed. It is also possible to provide irregularities on the surface to scatter light in the exposure step. Further, a light-absorbing paint can be applied to the uneven surfaces of the inner edge portions 4 and 14.

〔The invention's effect〕

As described above, according to the present invention, since the uneven surface is formed on the inner edge of the window provided in the wafer fixing disk, the light is absorbed by the light absorbing unevenness on the edge of the window of the disk. Light is scattered, the amount of light reflected from the edge of the window is greatly reduced, and overexposure does not occur due to interference of the reflected light, making it possible to perform exposure uniformly .

[Brief description of the drawings]

FIG. 1 is a plan view and a partially enlarged sectional view of an apparatus showing an embodiment of the present invention, FIG. 2 is an explanatory view of the operation of the present invention, and FIG. FIG. 4 is a plan view and a side sectional view showing an example of a conventional method, FIG. 4 is another embodiment of the present invention, and FIG. (Explanation of reference numerals) 1... Disk 2... Window 3... Pressing surface 4... Inner edge 5... Mat 6... Wafer storage 7. 9 An exposure mask.

Claims (1)

(57) [Claims] 1. A window for exposing a pattern formation region on a wafer surface coated with a resist, a pressing surface for pressing the periphery of the wafer in an annular shape from above, and a light scattering surface provided on an edge forming the window. A disc for fixing a wafer, characterized by having an uneven surface.