JP2624335B2 - Resist exposure method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist exposure method used in a photolithography process particularly in the field of semiconductor device manufacturing.

2. Description of the Related Art In recent years, a semiconductor device manufacturing method has become complicated, and the level difference on the surface of a semiconductor substrate to be processed has been increasing. On the other hand, pattern miniaturization has progressed, and dimensional tolerance has become smaller, and it has become extremely difficult to control the exposure amount of an exposure apparatus in a photolithography process.

Hereinafter, a conventional method for manufacturing a semiconductor device will be described.

FIG. 2 is a cross-sectional view of a photolithography step in a conventional method for manufacturing a semiconductor device. In FIG. 2, 1 is light emitted from a mercury lamp of an exposure apparatus, 2 is a quartz plate, 3 is a chromium pattern, 5 is a resist pattern, 6 is polycrystalline silicon, 8 is an oxide film, 9 is a silicon substrate, 11 Is the resist residue below the step. In a conventional method, an appropriate exposure amount is determined by measuring a dimension L of a resist pattern formed on a flat portion. That is, the desired resist dimension L
Was obtained, and there was no remaining resist 11 as shown in the recess in the figure.

However, in the above-described conventional method, the resist dimension L is a component in the lateral direction with respect to the silicon substrate, while the remaining resist 11 below the step is a component in the depth direction with respect to the silicon substrate. However, there is a drawback that the two cannot always cope sufficiently, and as a result, a resist residue 11 is generated below the step, or conversely, the resist dimension is reduced more than necessary due to an excessive exposure dose. Was.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a method of manufacturing a semiconductor device capable of preventing a resist remaining under a step and obtaining an appropriate resist size.

Means for Solving the Problems In order to achieve this object, a resist exposure method of the present invention comprises a light-transmitting glass substrate, a metal light-shielding film patterned on one main surface thereof and selectively blocking light, Patterned on the main surface at a position different from the metal light-shielding film, selectively attenuate the light intensity, a photomask pattern comprising a plurality of light translucent films having a plurality of different water transmittance, Centrally transferred onto a substrate coated with a resist by equal magnification or reduced projection exposure method, and after development, a flat portion where the pattern of the semi-transmissive film is transferred, a resist residue corresponding to the light transmittance is generated, A proper exposure amount is determined based on the remaining resist.

According to this method, the intensity of light passing through the photomask can be selectively changed, and the appropriate exposure amount is determined by measuring the film thickness of the resist remaining on the flat portion on the semiconductor substrate to be processed. be able to. That is, by monitoring the appropriate exposure amount that can prevent the resist remaining below the step on the semiconductor substrate to be processed and the corresponding resist remaining film amount in the flat portion, the appropriate exposure amount can be adjusted to the resist film thickness in the flat portion. Required from.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a cross section of a semiconductor substrate to be processed and a mask in a method of manufacturing a semiconductor device according to a first embodiment of the present invention. In FIG. 1, 1 is light emitted from a mercury lamp of an exposure apparatus, 2 is a quartz plate as a mask substrate, 3
Is a chrome pattern, 4 is a pattern of an organic film of a light semi-transmissive film, 5 is a patterned positive resist, 6 is polycrystalline silicon, 7 is a positive resist formed by a semi-transmissive film pattern, 8 is an oxide film , 9 are silicon substrates.

In FIG. 1, when a resist residue 7 occurs on a flat portion,
The film thickness is measured. Based on the film thickness, it can be determined whether or not the exposure amount at that time is a sufficient exposure amount that does not cause the resist to remain in the portion under the step 10. FIG. 1 shows four types of film thicknesses. In practice, however, a critical point at which an optimum resist residue occurs is obtained from a large number of continuous light transmissive patterns having different light transmittances. Can be easily measured.

As described above, according to the present embodiment, by providing a light semi-transmissive film of an organic film on a part of the mask, a predetermined resist residue 7 is generated on one flat portion on the semiconductor substrate to be processed, and the film thickness is reduced. By detecting, it is possible to determine an appropriate exposure amount without leaving a resist under the step.

In the first embodiment, the resist 5 is of a positive type.
The resist 5 may be a negative type. However, in that case, the light shielding part and the light transmitting part of the mask are reversed.

In the first embodiment, the polycrystalline silicon 6 and the oxide film 8 are examples of one process, and the present invention is not limited to these processes, and any material can be used.

As described above, the present invention has a light transmissive film that selectively attenuates light intensity with a pattern having a different pattern from the metal light shielding film of the mask, and the pattern is formed on a flat portion on the semiconductor substrate to be processed. By transferring the resist onto the flat surface and generating a resist residue on the flat portion, an appropriate exposure amount can be selected and accurate patterning can be performed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of one step of a method for manufacturing a semiconductor device according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view of one step of a method of manufacturing a conventional semiconductor device. 1 ... light, 2 ... quartz plate, 3 ... chrome pattern, 4 ...
... Semi-transparent organic film pattern, 5 ... Resist pattern, 6 ... Polycrystalline silicon, 7 ... Remaining resist, 8 ...
... Oxide film, 9 ... Silicon substrate, 10 ... Lower step, 11 ...
... resist remaining.

Claims (1)

(57) [Claims] 1. A light-transmitting glass substrate, a metal light-shielding film patterned on one main surface thereof to selectively block light, and a metal-light-shielding film patterned on the main surface at a position different from the metal light-shielding film. Attenuate the light intensity, the pattern of the photomask with a plurality of light semi-transmissive films having different water transmittance, centrally transferred onto a substrate coated with a resist by a 1: 1 or reduced projection exposure method, After the development, a resist residue corresponding to the light transmittance is generated on the flat portion where the pattern of the semi-transmissive film is transferred, and an appropriate exposure amount is determined based on the resist residue. Method.