KR20040046702A - Method for forming fine pattern of semiconductor device using double exposure - Google Patents

Abstract

PURPOSE: A method for forming a fine pattern of a semiconductor device by dual exposure is provided to prevent generation of sidelobe in forming a dense contact hole by separating a photomask for forming the dense contact hole into two photomasks with rare mask patterns and by forming a resist pattern by dual exposure. CONSTITUTION: An etch target layer is formed on a semiconductor substrate. Resist is applied to the upper surface of the etch target layer. The photomask corresponding to dense contact holes for forming the resist is divided into two masks to fabricate the first photomask(30a). The first exposure process is performed by using the first photomask. The second exposure process is performed on the firstly exposed resist by using the second photomask(30b). The twice-exposed resist is developed.

Description

TECHNICAL FOR FORMING FINE PATTERN OF SEMICONDUCTOR DEVICE USING DOUBLE EXPOSURE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a fine pattern of a semiconductor device, and more particularly, to a method for preventing sidelobe generation in forming dense contact holes.

As is well known, a semiconductor device is manufactured by repeatedly performing the deposition process of a conductive film and an insulating film, the mask formation process by a photolithography process, and the etching process using a mask.

Here, the photolithography process is a process of forming an arbitrary resist pattern by applying, exposing and developing a resist on an etching target layer, and the critical dimension of the actual pattern to be formed on the substrate (hereinafter, referred to as CD) is It is greatly influenced by the CD of the pattern that can be realized in the photolithography process.

To date, semiconductor technology has been advanced by simply selecting a light source used in a reduction exposure apparatus for shortening a pattern CD according to high integration.

For example, conventionally, a light source of G-line (λ = 436 nm) or I-line (λ = 365 nm) was used, but due to the limitation of the resolution, it was difficult to form a fine pattern having a CD of 0.35 μm or less. By using a KrF (λ = 248 nm) light source, it is possible to form a fine pattern having a CD of about 0.15 μm. In recent years, a CD of about 0.10 μm is used by using an ArF (λ = 193 nm) light source. Formation of a fine pattern having

However, as the integration of semiconductor devices increases, design rules are reduced, and thus, a conventional photolithography process cannot accurately form a fine pattern as a mask pattern drawn on an exposure mask in an entire area of a substrate.

That is, in forming a dense contact hole array having a small size on a semiconductor substrate, a conventional method irradiates a single dose to a substrate using an exposure mask on which a contact pattern mask pattern is drawn, thereby forming contact holes. In the case of a dense contact hole, as shown in FIG. 1, a sidelobe is generated in a portion surrounded by the contact holes 2 so that the hole should not be formed in an undesired area after the development process. The problem that (3) is formed arises.

FIG. 2 shows the tailed aerial image intensity of the tailed aerial image resulting in side lobes in contact hole patterning, where A is the intensity of the actual contact hole image, and B is the tail. Type Shows the intensity of the error image, respectively.

Accordingly, an object of the present invention is to provide a method for forming a fine pattern of a semiconductor device using double exposure, which is devised to solve the above problems and can prevent side lobe generation during the formation of dense contact holes. .

1 is a view for explaining a side lobe generated in a conventional contact hole forming mask.

2 shows the intensity of a tailed aerial image that generates side lobes.

3 is a view showing an exposure mask for forming a contact hole formed in accordance with an embodiment of the present invention.

4 is a view showing an exposure mask for forming a contact hole formed in accordance with another embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

30a, 40a: first exposure mask 30b, 40b: second exposure mask

32,42: Mask Pattern

In order to achieve the above object, the present invention, an etching target layer is formed on the upper surface and providing a semiconductor substrate coated with a resist on the etching target layer; Firstly exposing an exposure mask corresponding to the dense contact holes to form the resist into two masks using a first exposure mask manufactured by dividing the exposure mask into two masks; Secondarily exposing the first exposed resist using a second exposure mask fabricated separately; And it provides a method of forming a fine pattern of a semiconductor device using a double exposure comprising the step of developing the resist exposed two times.

The method further includes reflowing the resist after the second exposure and before developing the resist, wherein developing the resist comprises 2.5 wt% TMAH (TetraMethyl-Ammonium Hydroxide) solution.

According to the present invention, a contact forming exposure mask for forming a dense contact hole is manufactured by dividing into two masks, and exposure is performed twice using these divided masks to prevent occurrence of side lobes. Thus, dense contact holes can be stably formed without the formation of unwanted holes.

(Example)

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

In the method of forming a fine pattern of the present invention, the exposure mask for forming a dense contact hole is divided into two exposure masks having a non-dense mask pattern, and double exposure is performed using each of the exposure masks thus manufactured. Dense contact holes are formed over the entire area of the substrate without the occurrence of lobes.

3 is a view illustrating an exposure mask for partially forming a contact hole according to an embodiment of the present invention.

As shown, the present invention separately fabricates the dense contact hole forming exposure mask into two exposure masks 30a and 30b having non-dense mask patterns 32.

In this case, since the interval between the mask patterns 32 provided in each of the exposure masks 30a and 30b is not narrow, side lobes are not generated as the exposure masks are exposed using the exposure masks 30a and 30b. In addition, even if there are side lobes, the unwanted lobe pattern is not formed by the side lobes because the pieces do not merge together.

In detail, the method of forming a fine pattern of the present invention using the exposure masks manufactured as described above is as follows.

First, a resist is coated on the insulating film while the etching target layer, that is, the insulating film having the surface planarization is formed on the semiconductor substrate.

Then, the first exposure is performed using any one of the two exposure masks 30a and 30b separately manufactured for the resist, for example, the first exposure mask 30a.

Subsequently, secondary exposure is performed to the first exposed resist using the remaining second exposure mask 30b.

Next, the size of the contact hole to be formed is reduced by reflowing the double exposed resist.

Then, the double exposed resist is developed using a 2.5 wt% TMAH solution higher than 2.38 wt% TMAH (TetraMethyl-Ammonium Hydroxide), thereby forming a contact hole forming resist pattern.

Thereafter, the insulating pattern, which is an etch target layer, is etched using the resist pattern to finally form a dense contact hole array.

4 is a view illustrating an exposure mask for forming a contact hole separately manufactured according to another exemplary embodiment of the present invention.

As shown, the first and second exposure masks 40a and 40b for forming the dense contact holes according to this embodiment are, for example, the mask patterns 42 in the horizontal direction are densely formed, but in the vertical direction. The mask patterns 42 in E are not formed densely.

In this case, although there may be an overlap of the aerial image intensities in the transverse direction, the peak of the overlapped intensities is not so large that unwanted formation of holes does not occur.

As a result, even when the exposure mask is fabricated in this manner, the occurrence of side lobes can be prevented.

As described above, according to the present invention, after forming the dense contact hole forming exposure mask into two exposure masks having non-dense mask patterns, the present invention forms a resist pattern through double exposure using the same. The generation of side lobes at the time of hole formation can be prevented, so that the reliability of pattern formation can be ensured and a denser contact hole array can be formed.

In addition, this invention can be implemented in various changes within the range which does not deviate from the summary.

Claims (3)

Providing a semiconductor substrate having an etching target layer formed on an upper surface thereof and a resist coated on the etching target layer; Firstly exposing an exposure mask corresponding to the dense contact holes to form the resist into two masks using a first exposure mask manufactured by dividing the exposure mask into two masks; Secondarily exposing the first exposed resist using a second exposure mask fabricated separately; And And developing the exposed resist twice. 2. The method of claim 1, further comprising reflowing the resist after the second exposure and before developing the resist. The method of claim 1, wherein developing the resist Method for forming a fine pattern of a semiconductor device using a double exposure, characterized in that carried out using 2.5wt% TMAH (TetraMethyl-Ammonium Hydroxide) solution.