KR100326430B1 - Method for forming photo resist in semiconductor device - Google Patents

Abstract

PURPOSE: A method of forming a photoresist pattern as a mask for metal wiring pattern in semiconductor process is provided, to improve a profile of photoresist pattern, thereby enhancing the reliability of metal wiring pattern process to increase the yield of semiconductor device manufacturing process. The method can be applied to the formation of micro-pattern. CONSTITUTION: The method of forming the photoresist pattern of semiconductor devices comprises a process of forming photoresist(3) on the top of a metal layer(2) formed on the semiconductor substrate(1); a process of forming a reflective membrane(4) of water-soluble tar on the photoresist(3); a process of exposing the photoresist(3) selectively according to a desired pattern; and a process of removing the exposed area in the photoresists(3) to form the photoresist pattern.

Description

Photosensitive film pattern formation method of a semiconductor device {METHOD FOR FORMING PHOTO RESIST IN SEMICONDUCTOR DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the formation of a photosensitive film pattern in a photo process, and more particularly to a method of forming a photosensitive film pattern suitable for improving the profile of the photosensitive film pattern.

In general, in the semiconductor device manufacturing process technology, the photoresist pattern is used as a mask for injecting impurities into a selected region of a semiconductor substrate or an etching mask for patterning a wiring conductor into a predetermined shape during a wiring process for connecting a device formed on the semiconductor substrate. It is used as.

At this time, when the photosensitive film pattern is formed as a mask for a conductor pattern for patterning a wiring conductor, a positive or negative photosensitive film is coated on the conductor, and a photo-mask having a pattern having a predetermined shape is positioned above the photosensitive film. As a light source for exposing the photoresist film, the photoresist film is exposed according to the shape of the pattern formed on the photomask using ultraviolet rays, electron beams, X-rays, lasers, and the like, and then the exposed portion of the photoresist film (positive photoresist film). ) To form a photoresist pattern on the conductor, and the photoresist is removed to remove the exposed conductor with an etching solution to pattern the conductor to form metal wiring for connecting each element on the semiconductor substrate.

However, in the photo-process for forming the photoresist pattern as described above, as the size of a single device is reduced according to the high integration of the semiconductor device, the line width of the wiring is reduced to 0.5 μm or less. Has become an important key to increasing

Therefore, the photoresist pattern formed on the upper side of the material to be patterned should have good adhesion with the contacting material, have a uniform profile, and be formed at the designated position with the correct width in order to improve the reliability of the semiconductor device manufacturing process. .

However, depending on the type of material located in the lower layer of the photoresist film, during the photoresist exposure process, the part to be unexposed in the photoresist film is exposed by the diffuse reflection of the incident light according to the characteristics of the light of the lower layer material, thereby performing the development process after the exposure process. When the photoresist pattern is formed, a portion of the photoresist pattern is formed to have an inclination from the lower side to the upper side because the portion to be formed as the photoresist pattern is removed from the lower side to the upper side under the influence of diffuse reflection, so that the lower portion of the photoresist pattern is formed. At the side edge portion, the thickness of the photosensitive film is made thin.

Accordingly, during the subsequent etching process following the formation of the photoresist pattern, the thin photoresist thickness of the lower edge portion of the photoresist pattern may not serve as a mask for the material to be etched, thereby contacting the bottom edge portion of the photoresist pattern. The overetch of the etching material at the interface of the etching material occurs inward, so that the etching material under the photoresist pattern cannot be patterned with the designed line width.

Therefore, in order to solve the above problems, the side surface of the photoresist pattern formed on the upper portion of the etching material is formed vertically, and the thickness of the photoresist process must be uniform over the entire width to ensure the reliability of the photo-etching process. You can increase it.

Hereinafter, with reference to the accompanying drawings will be described in the prior art.

1 (a) to (d) show a cross-sectional view of a conventional photoresist pattern forming process. After fabricating devices on a semiconductor substrate 11, interconnecting each device to form wiring for constituting a circuit Metal layer as a conductive material for interconnecting each element as shown in FIG. 1 (a) on a semiconductor substrate 11 having exposed portions contacting wiring conductors and portions insulated with an insulating material (not shown). (12) (Aluminum, for example), and as shown in FIG. 1 (b), a mask pattern for wiring formation is formed on the metal layer 12 for the purpose of preventing profile deterioration of the photosensitive film pattern due to diffuse reflection of incident light during the exposure process. The positive photosensitive film 13 containing the dye as a forming material is uniformly coated.

Subsequently, as illustrated in FIG. 1C, the chromium pattern 5 having a predetermined width and shape is selectively exposed to the photoresist film 13 using the photomask 6 having one surface, and remains in the subsequent development process. The non-exposed area 13a and the exposed area 13b to be removed are defined.

Next, as illustrated in FIG. 1D, the metallization pattern having a predetermined width in the selected region on the metal layer 12 is removed by removing the exposure area 13b exposed to light in the photosensitive film (reference numeral 13 in FIG. 1C). The photosensitive film pattern 130 is formed as a mask for a mask.

The photosensitive film pattern 130 formed on the metal layer 12 may be patterned according to the angle of light reflected on the metal layer 12 through the photosensitive film 13 during the exposure process of the photosensitive film (reference numeral 13 in FIG. 1C). The side surface of the non-exposed area 13a to be formed as a mask is exposed obliquely from the lower side and removed obliquely from the upper side to the lower side during the development of the exposed area 13b, so that the lower width is the same width as that of the chrome pattern 5 on the photomask 6. Although the upper width has a width smaller than the width of the chrome pattern 5, the photosensitive film pattern 130 having a gentle inclined side portion is formed.

Therefore, when the photosensitive film pattern 130 is formed as the pattern mask on the metal layer 12 by patterning the metal layer 12 in the conventional technology as described above, the lower edge portion of the photosensitive film pattern 130 is thin and the metal wiring is formed. In the etching process for forming the film, an overetch of the metal layer 12 is generated inward from this portion, and thus a wiring having a width smaller than the width of the designed wiring is formed, resulting in a failure of the photo-etching process and lowering the process yield. There was this.

Accordingly, an object of the present invention is to solve the above problems, and an object thereof is to improve the profile of the photoresist pattern.

The present invention for the above object is a process for forming a positive photoresist film on the metal layer, forming a reflective film on the photosensitive film, exposing the photoresist film according to a predetermined pattern, and an exposure area in the photosensitive film And removing the photoresist pattern.

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

2 (a) to 2 (d) show cross-sectional views of the photosensitive film pattern forming process of the present invention. As shown in FIG. 2 (a), after fabricating an element (not shown) on the semiconductor substrate 1, each individual On an insulating substrate (not shown) and on a semiconductor substrate 1 having exposed portions that are in contact with the wiring material to interconnect the devices and portions (not shown) that are covered with insulating paper to insulate the device from the upper wiring. The metal layer 2 (for example, aluminum) is formed as a wiring forming material over.

Subsequently, as shown in FIG. 2B, a positive photosensitive film 3 is formed as a material for forming a pattern mask for forming metal wiring on the metal layer 2, and then incident light is applied to the photosensitive film 3 during an exposure process. A reflective film 4 is formed on the photosensitive film 3 as a water-soluble tar having a thickness of 600 kPa to 800 kPa on the photosensitive film 3 in order to prevent the portion of the photosensitive film 3 that is to be reflected from the metal layer 2 to be exposed. .

In this case, the thickness of the reflective film 4 formed on the photosensitive film 3 is adjusted by the user according to the refractive index characteristic of the photosensitive film 3. That is, when the refractive index of the photosensitive film 3 to the ultraviolet light is large, the thickness of the reflective film 4 is formed to be 2 to 3 times the thickness of 600 ~ 800Å thickness range to perform the exposure process.

Subsequently, in order to form the photoresist pattern as illustrated in FIG. 2C, the photoresist 6 is formed using a photomask 6 having a chromium pattern 5 having a predetermined width and a predetermined shape on one surface thereof. 3) is exposed to ultraviolet rays according to the shape of the chrome pattern 5 to define the non-exposed area 3a and the exposed area 3b of the photosensitive film 3. At this time, the light transmitted through the photosensitive film 3 of the exposure area 3b and reflected by the metal layer 2 is absorbed and transmitted through the reflective film 4 to reduce the effect on the photosensitive film 3 of the non-exposed area 3a. do.

Next, as shown in FIG. 2 (d), the number of reflection films was removed, and the exposure area 3b of the photosensitive film 3 was removed with a developing solution, and the chrome pattern 5 on the photomask 6 was removed in the selected area on the metal layer 2. A photosensitive film pattern 30 having the same width as the above is formed.

At this time, the photoresist pattern 30 is formed by absorbing and transmitting light diffusely reflected from the metal layer 2 having the reflective film 4 formed on the photoresist 3 located below the non-exposed area 3a of the photoresist film 3. The side portion of is to reduce the phenomenon that is exposed by the diffuse reflection occurs on the surface of the metal layer (2).

Therefore, the photosensitive film pattern formation method of this invention which forms the reflective film 4 on the photosensitive film 3, and then exposes and patterns the photosensitive film 3, The metal layer below the exposure area | region 3b of the photosensitive film 3 exposed to ultraviolet-ray. The reflection film 4 absorbs and transmits the diffuse reflection of the light generated in (2) so that the non-exposed region 3a is inclined upward by the diffuse reflection at the interface between the non-exposed region 3a and the exposed region 3b. This can prevent the phenomenon. As a result, the difference in length between the upper and lower widths of the formed photosensitive film pattern 30 is significantly reduced as compared with the prior art, so that the sidewalls are formed at an angle close to the vertical, thereby improving the profile of the photosensitive film pattern 30.

Accordingly, the line width of the metal wiring is less than the designed width (width of the chrome pattern) by the overetching of the metal layer 20 inside the lower edge portion of the photosensitive film pattern 30 during the etching process for forming the metal wiring. By eliminating the problems of the prior art formed by the width, the reliability of the photo-etching process in the semiconductor manufacturing process is increased, thereby increasing the semiconductor process yield.

1 (a) to (d) are cross-sectional views of a conventional process for forming a photosensitive film pattern.

Figure 2 (a) to (d) is a cross-sectional view of the process for forming a photosensitive film pattern according to a preferred embodiment of the present invention.

Claims (4)

In the photosensitive film pattern formation method of a semiconductor element Forming a photosensitive film on top of the metal layer formed on the semiconductor substrate, Forming a water-soluble tar reflective film on the photosensitive film; Selectively exposing the photosensitive film according to a predetermined pattern; And a photoresist pattern is formed by removing an exposure area of the photoresist. The method of claim 1, wherein aluminum is used as a material of the metal layer. The method of forming a photosensitive film pattern of a semiconductor device according to claim 1, wherein the reflecting film (4) has a thickness in the range of 600 to 800 kPa. The method of forming a photosensitive film pattern of a semiconductor device according to claim 3, wherein the thickness of the reflective film (4) is formed to be 2 to 3 times the thickness of the photosensitive film according to the size of the refractive index.