KR20010047286A - Exposure method for forming micro-patterns - Google Patents

Abstract

PURPOSE: An exposing method for forming a fine pattern is provided to prevent the resolution from lowering due to the interference of light by arranging a slit between a light source for exposing and a mask for exposing to the direction vertical to the direction of the light. CONSTITUTION: A slit(26) is arranged between a light source(20) and a mask(26) for exposing, and a lens(27) and a wafer(28) are arranged on the lower part of the mask(26) in turns. The first light(L4) from the light source(20) is diffracted to the second light(L5) via a slit(23), the second light(L5) is diffracted to the third light(L6) via the mask(26), and the third light(L6) is diffracted to the fourth light(L7) via the lens(27), so that a photosensitive film formed on the wafer(28) is exposed by the fourth light(L7).

Description

Exposure method for forming micro-patterns}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure method for forming a fine pattern. In particular, a slit is scanned between a light source for exposure and an exposure mask in a direction perpendicular to the traveling direction of light to reduce resolution due to interference of light, which is one of the characteristics of light. The present invention relates to an exposure method for forming a micropattern having a line width of less than or equal to the limit resolution caused by exposure of a semiconductor device, which is improved by reducing interference conditions.

As semiconductor devices become more integrated and denser, the size of the unit element is reduced, and as a result, the line width of the conducting wire is reduced. Therefore, a photolithography process using an exposure method such as a contact printing method, a proximity printing method, and a projection printing method is used to form a fine pattern.

The exposure mask includes a light blocking area and a light transmitting area to expose the photosensitive film with a pattern of light passing through the light transmitting area by passing light emitted from the light source during exposure.

If any obstacle exists in the path through which light waves propagate, the amplitude and phase of the wavefront of the light waves passing through it appear. This change is called diffraction.

In the case of using the exposure apparatus according to the related art, light is generated by a stepper or an optical scanner of the exposure apparatus, and then the light is transmitted through an exposure mask in which a pattern is defined and transferred to the wafer.

Therefore, diffraction also occurs in the light passing through the lens. Interference is the superposition of a few waves compared to diffraction, and the diffraction is the result of a very large number of waves of light overlapping.

1 is a schematic diagram showing an exposure method according to the prior art.

Referring to FIG. 1, an exposure mask 13 including a transparent substrate 11 and a light blocking film 12 is prepared. A light blocking film 12 having a pattern to be projected on a wafer is defined at a lower end of the transparent substrate 11 made of quartz or glass. In this case, the light shielding film 12 is formed to a predetermined thickness using Cr and CrOx as the conductive material.

Therefore, a portion where the light shielding film 12 pattern is formed becomes a light shielding area that prevents light from passing through during exposure, and a part where the light shielding film 12 is not formed becomes a light transmitting area.

In the exposure process, the first light L1 generated from the light source 10 is diffracted while passing through the mask 13 to become the first diffracted light L2, and then passes through the lens 14 to the second diffracted light L3. Changes to).

The second diffracted light L3 is projected onto the wafer 15 on which the photosensitive film is applied.

However, due to the characteristics of light, diffraction occurs through Fourier transform in the light passing through the mask 13 and the lens 14.

Therefore, the exposure method for forming a micropattern according to the related art described above causes bridges between pattern shapes projected on the photoresist due to diffraction and interference of light generated through the mask and the lens, resulting in high integration of the semiconductor device. There is a problem that can not ensure the reliability of the ultra-fine pattern formed by the reduction of the chip size.

Accordingly, an object of the present invention is to improve the resolution by reducing the interference condition to reduce the resolution by the interference of the light, which is one of the characteristics of the light by installing a slit scanning in the direction perpendicular to the direction of light between the exposure light source and the exposure mask. An exposure method for forming a fine pattern having a line width of less than or equal to the limit resolution caused by exposure of a semiconductor device to be made.

In order to achieve the above object, an exposure method for forming a micropattern according to the present invention includes placing a slit having a predetermined light blocking area and a light transmitting area between a light source and an exposure mask in which predetermined patterns are defined, and a lens and a wafer under the exposure mask. And transferring light onto the wafer by generating light from the light source and simultaneously scanning the slit from one end of the exposure mask to the other end. In this case, the light shielding area of the slit is formed to have a size of shielding the remaining part of the exposure mask except for the exposure area by the light transmitting area of the exposure mask during scanning.

1 is a schematic diagram showing an exposure method according to the prior art.

2 is a schematic diagram showing an exposure method for forming a fine pattern according to the present invention.

In photolithography during the semiconductor device manufacturing process, light interference inevitably occurs in the photolithography method using a lens of an exposure device, and such interference or diffraction is a more lethal factor in pattern formation due to the reduction in chip size. Works.

In the present invention, by adopting a method of mechanically dividing exposure of the light interference or diffraction using a slit to be scanned, it is possible to form a finer and more dense pattern by mechanically reducing the interference conditions of light. That is, in the exposure apparatus using the conventional exposure method, a slit moving perpendicularly to the traveling direction of the light is further provided between the light source as the exposure source and the exposure mask to reduce the temporal coherence of light.

As a result, it is possible to overcome the marginal resolution of the exposure apparatus by allowing diffraction light to reach a photosensitive film formed on a wafer independently with a parallax without mutual interference between patterns such as holes with a very small pitch interval.

In other words, the present invention inserts a slit having a width narrower than the light emission area interval of the exposure mask pattern between the light source and the exposure mask in order to reduce the electrical coherence described above, and simultaneously exposes the slit in the direction perpendicular to the exposure direction. Scan the. In this case, the width of the slit should be smaller than the pattern interval because the slit is scanned and when exposing one pattern, the neighboring pattern should be blocked by the light shielding area of the slit so that the time difference of exposure time of each pattern may occur. Because.

That is, when the slit is scanned from left to right, for example, the scanning speed of the slit cannot be faster than the luminous flux since the scanning speed is determined by the mechanical operation. Once the exposure is started, only the first left pattern of the exposure mask is exposed, and in turn, the slits move and the second, third ... n-th pattern is exposed. Therefore, the effect by interference of the bridge or the like at the exposed portion of the diffracted light which is well formed on the wafer is eliminated, and the pattern can be formed even at a smaller pattern pitch below the limit resolution.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

2 is a schematic diagram showing an exposure method for forming a fine pattern according to the present invention.

Referring to FIG. 2, a first light shielding pattern 21 made of a light blocking material such as chromium may be formed in a trench of a long groove shape formed on the first transparent substrate 22 made of quartz or glass and the first transparent substrate 22. Prepare a slit made of).

In addition, an exposure mask 26 including a second light blocking film pattern 25 having a second transparent substrate 24 and an image pattern to be transferred to the wafer 28 is prepared. That is, on one side of the second transparent substrate 24 made of quartz or glass, a second light shielding film pattern 25 having a pattern to be projected on the wafer is defined. In this case, the second light blocking film pattern 25 is formed to have a predetermined thickness using Cr, CrOx, or the like as the conductive material.

Therefore, a portion where the pattern of the second light shielding film 25 is formed becomes a light shielding area that prevents light from passing through during exposure, and a portion where the second light shielding film pattern 25 is not formed becomes a light transmitting area.

In the exposure process using the slits 23 and the exposure mask 26 prepared as described above, the slits 26 are positioned between the light source 20 and the exposure mask 26 and the lens 27 and the lower part of the exposure mask 26. The wafers 28 are sequentially positioned so that the first light L4 starting from the light source 20 passes through the slit 23 to be diffracted into the second light L5, and the second light L5 is exposed again. The third light L6 is diffracted into the third light L6 through the mask 26, and the third light L6 is diffracted into the fourth light L7 through the lens 27 and finally on the wafer 28. The formed photosensitive film (not shown) is exposed.

In the embodiment according to the present invention, the width of the light transmitting area of the slit 23 is smaller than the width of the light transmitting area of the exposure mask 26. This is because, while the slit 23 is scanned perpendicularly to the direction in which the first light L4 is incident, the second light L5 passing through the light-transmitting region of the slit 23 is formed between the second light blocking film patterns 25. This is to allow only the light transmitting area to pass through specifically. That is, when one light transmitting area of the exposure mask 26 is exposed, the neighboring light transmitting area is for blocking by the first light shielding film pattern 21 of the slit 26.

In this manner, the fourth light L7 transmitted through the exposure mask has a time difference and is sequentially transferred onto the wafer 28. Therefore, the fourth light L7 passing through the independent light-transmitting regions between the second light shielding film patterns 25 of the exposure mask 26 does not interfere with each other.

In the exposure method according to the present invention, first, the first light L4 generated by the light source 200 passes through the light-transmitting region of the slit 23 and locally passes through the light-transmitting region of the exposure steel mask 26 to pass through the wafer (the lens). The predetermined patterns of the exposure mask are transferred onto 28.

Therefore, in the exposure method for forming a micropattern according to the present invention, since the light partially arrives on the wafer, the wavelength of light is reduced because the interference coherence of the light is reduced to a minimum as compared with the case of exposing the entire surface of the wafer by one irradiation. There is an advantage in that a precise pattern can be formed even at a smaller pattern pitch below the limit resolution.

Claims (5)

Positioning a slit having a predetermined light blocking area and a light transmitting area between a light source and an exposure mask in which predetermined patterns are defined, and placing a lens and a wafer under the exposure mask; And generating the light from the light source and simultaneously transferring the slit from one end of the exposure mask to the other end to transfer the patterns onto the wafer. The exposure method of claim 1, wherein the width of the light transmitting area of the slit is smaller than a pitch between the patterns. The exposure method according to claim 1, wherein the length of the light transmitting region of the slit is formed to be equal to or larger than the diameter of the wafer. The method of claim 1, wherein the scanning direction of the slit is perpendicular to a traveling direction of the light. The method of claim 1, wherein the light shielding area of the slit is formed to have a size that shields the remaining part of the exposure mask except for the exposure area of the exposure mask by the light transmitting area. .