JP2886193B2 - Semiconductor wafer exposure method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for exposing a semiconductor wafer used in a semiconductor device manufacturing process.

[Conventional technology]

In the process of manufacturing semiconductor devices, generally, a large number of semiconductor chips are formed on a thin disk-shaped semiconductor wafer,
Various processes such as photolithography, etching, and ion implantation are collectively performed.

The exposure apparatus is known, for example, in "Electronic Materials Separate Volume, Ultra LSI Manufacturing / Testing Equipment, Guidebook", pp. 97-104, "Light Exposure Equipment", published by the Industrial Research Institute in 1984.

[Problems to be solved by the invention]

Since a large number of rectangular semiconductor chips are formed on a circular semiconductor wafer, a step-like unnecessary region (hereinafter, referred to as an unnecessary region) exists at a peripheral portion of the wafer. Therefore, when a pattern is formed by using the photolithography technique, the photoresist is applied to the entire surface of the wafer, so that the unnecessary area is also coated with the photoresist, and the unnecessary area is not exposed. It remains as it is, and when holding the peripheral portion of the wafer in a later dry etching step, ion implantation step, or the like,
The photoresist is peeled off to form foreign matter, which causes a problem that the performance of the semiconductor element is reduced or the yield is reduced.

An object of the present invention is to provide a method for exposing a semiconductor wafer, which can prevent the generation of such foreign matter.

[Means for solving the problem]

In order to solve the above-mentioned problems, a method of exposing a semiconductor wafer according to the present invention is a method of exposing a semiconductor wafer coated with photoresist with light from an exposure light source, wherein the exposed surface of the semiconductor wafer is rotated. A step of two-dimensionally moving a lens for irradiating the light of the exposure light source in parallel with a surface to be exposed of the semiconductor wafer, and a step of using a shutter provided between the exposure light source and the lens. And a step of selectively exposing an unnecessary region excluding a region where the semiconductor element is formed on the semiconductor wafer to a shape along a boundary between the region where the semiconductor element is formed and the unnecessary region.

[Action]

In the present invention, an unnecessary region excluding a region where a semiconductor element is formed on a semiconductor wafer coated with a photoresist is selectively exposed to a shape along a boundary between the region where the semiconductor element is formed and the unnecessary region. Accordingly, the photoresist in the unnecessary area can be removed, and no foreign matter is generated even if the peripheral portion of the wafer is held.

〔Example〕

FIG. 1 is a schematic view showing a semiconductor manufacturing apparatus according to a reference example of the present invention, and FIG. 3 is a schematic plan view of a semiconductor wafer.

In FIG. 1, 1 is a rotary stage, 2 is a semiconductor wafer, 3
Denotes a light source such as an Hg lamp, 4 denotes a lens, 5 denotes a mask, and 6 denotes a motor. In FIG. 3, reference numeral 7 denotes an orientation flat portion (hereinafter referred to as an orientation flat portion) for knowing the direction of the semiconductor wafer 2, 8 denotes a semiconductor chip (element portion), and 9 denotes a step-like unnecessary area (actually, the number of chips 8). Because there are more
Unnecessary area 9 has more steps), 10 is semiconductor wafer 2
Is a mark for identifying.

A semiconductor wafer 2 coated with a positive photoresist is held on a rotary stage 1 by suction. Light from the light source 3 is guided to the unnecessary area 9 of the wafer 2 via the lens 4,
Irradiation is performed through the mask 5. The mask 5 is rotated by a motor 6, and the periphery of the wafer 2 is exposed by a pattern formed on the mask 5 (a stepped pattern for exposing the unnecessary area 9 and a pattern of the identification mark 10 in FIG. 3). You.

FIG. 2 is a schematic view showing one embodiment of a semiconductor manufacturing apparatus used for the method of exposing a semiconductor wafer according to the present invention.

The light from the light source 3 processed by the shutter 13 driven in the direction of the arrow is applied to the lens 4, the optical fiber 12 and the lens 11 with respect to the rotary stage 1 and the wafer 2 similar to FIG.
Is irradiated to the peripheral portion of the wafer 2 via the. At this time, the peripheral edge of the wafer 2 can be selectively exposed by driving the lens 11 in the direction of the arrow above the peripheral edge of the wafer 2.

FIG. 3 shows an example of a semiconductor wafer exposed by the apparatus shown in FIGS. The element portion, that is, the step-like unnecessary area 9 outside the semiconductor chip 8 is exposed, and the orientation mark 7 is exposed on the orientation flat portion 7. By developing the semiconductor wafer 2, the photoresist in the unnecessary area 9 is removed, and the identification mark 10 is formed on the orientation flat section 7. That is, since the photoresist at the peripheral portion of the semiconductor wafer 2 can be removed, the uniformity of the etching rate in the wafer in a later step, for example, an etching step is improved, and the photoresist is peeled off by a mechanism that contacts and holds the wafer peripheral portion. The generation of foreign matter can be suppressed. Therefore, the performance of the element and the yield can be improved. Further, since the identification mark 10 can be formed at the same time, the efficiency of product management is improved.

In the reference example shown in FIG. 1, the wafer 2 is rotated, and the mask 5 on which a predetermined pattern is formed is mechanically driven to selectively expose the periphery of the wafer 2. In the embodiment shown in FIG. 2, the wafer 2 is rotated, and the lens 11 for irradiating the light processed by the shutter 13 is driven to selectively expose the periphery of the wafer 2. However, the configuration in FIG. 2 is an exemplification, and the present invention is not limited to these. For example, the third
As shown in the figure, the peripheral portion of the wafer does not necessarily need to be exposed in a stepwise manner, and at least a portion to be held in a later step may be exposed.

〔The invention's effect〕

As described above, in the method for exposing a semiconductor wafer according to the present invention, the photoresist at the peripheral portion of the semiconductor wafer can be removed, so that it is possible to prevent the photoresist from peeling off in a later step to generate foreign matter. Therefore, the performance of the element and the yield can be improved. Further, since the wafer identification mark can be formed, the efficiency of product management can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a semiconductor manufacturing apparatus according to a reference example of the present invention, FIG. 2 is a schematic view showing one embodiment of a semiconductor manufacturing apparatus used for a semiconductor wafer exposure method of the present invention, and FIG. ,
1 is a schematic plan view of a semiconductor wafer exposed by the method of the present invention. DESCRIPTION OF SYMBOLS 1 ... Rotary stage 2 ... Semiconductor wafer 3 ... Light source 4 ... Lens 5 ... Mask 6 ... Motor 7 ... Orientation flat part 8 ... Semiconductor chip (element part) 9 ... Unnecessary step-like area 10 ... … Semiconductor wafer identification mark 11 …… Lens 12 …… Optical fiber 13 …… Shutter

Claims (1)

(57) [Claims] 1. A method of exposing a semiconductor wafer coated with a photoresist with light from an exposure light source, the method comprising: rotating a surface of the semiconductor wafer to be exposed; A step of two-dimensionally moving the semiconductor wafer in parallel with a surface to be exposed, and an unnecessary area excluding an area where semiconductor elements of the semiconductor wafer are formed by a shutter provided between the exposure light source and the lens. Selectively exposing the semiconductor wafer to a shape along a boundary between a region where the semiconductor element is formed and the unnecessary region.