KR20110001289A - Lithography Mask - Google Patents

Abstract

The present invention discloses a mask for lithography which is used in a photolithography process in the manufacturing process of a semiconductor device.

The lithographic mask of the present invention inserts auxiliary patterns on both sides of the contact patterns arranged in a zigzag form, but uses auxiliary patterns having different lengths together to minimize the influence of mask error, thereby reducing the intensity of light on the contact patterns. Improves.

Description

Mask for photolithography

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to masks used in the manufacture of semiconductor devices, and more particularly to masks for lithography for patterning a photosensitive film.

As semiconductor devices are highly integrated, the size of semiconductor devices is reduced. In particular, in the case of flash memory, more devices must be integrated on a semiconductor substrate in order to increase memory storage capacity. Therefore, the density of semiconductor devices is increasing and the circuit configuration thereof is also very complicated.

FIG. 1A illustrates a conventional lithography mask for forming a drain contact applied to a flash memory, and FIG. 1B illustrates a drain contact pattern formed by using the lithography mask of FIG. 1A. Drawing.

On the conventional drain contact mask, patterns defining the drain contact region are arranged in a line. However, when the patterns are arranged in a line in one direction, when the etching process proceeds due to the small gap between the drain contacts formed by the pattern, there is a possibility that a bridge occurs between the contacts as shown in FIG. 2. The higher the memory, the higher the memory density. In particular, since the energy is concentrated in the center of the contact during the exposure process, a bridge is likely to occur between the centers of adjacent contacts.

In order to solve this problem, conventionally, a method of forming contacts in a zigzag form as shown in FIG. 3 without arranging the contacts in one direction has been proposed.

However, as the zigzag contact hole increases in the degree of integration of semiconductor devices and the design rule decreases sharply, an EL (Exposure Latitude) and a DoF (Depth of Focus) margin decrease as shown in FIG. 4. Doing. That is, compared with DoF (> 150 nm) and EL (> 12%) which are necessary for mass production, it is a situation lacking much.

The present invention seeks to provide a new type of mask for lithography that can improve the EL and DoF margins of the zigzag contact holes described above.

The lithographic mask of the present invention for solving the above problems is defined by a mask substrate, a light shielding pattern formed on the mask substrate and a light shielding pattern, and a light transmission pattern having a plurality of auxiliary patterns formed at different lengths on at least one side of the contact pattern It includes.

As described above, the mask for lithography of the present invention minimizes the influence of mask error that may occur when forming a short auxiliary pattern by inserting an auxiliary pattern but using auxiliary patterns having different lengths together to reduce the intensity of light with respect to the contact pattern. Improves.

In this case, the contact pattern may be a drain contact pattern formed in a zigzag shape, in which case the auxiliary pattern is formed on both sides of the contact pattern.

The auxiliary pattern includes a first auxiliary pattern and a second auxiliary pattern having a length longer than that of the first auxiliary pattern and formed between the first auxiliary pattern and the contact pattern. In this case, the first auxiliary pattern may be a line pattern extending in the major axis direction of the second auxiliary pattern, a line pattern extending in the minor axis direction of the second auxiliary pattern, or a dot pattern. The second auxiliary pattern may be formed such that a plurality of line patterns having a length corresponding to a predetermined number of contact patterns are arranged in a line or a single line pattern having a length corresponding to the entire contact pattern. .

The present invention minimizes the influence of mask error that may occur when forming a short auxiliary pattern to improve the intensity of light on the contact pattern.

The present invention is characterized in that the auxiliary pattern is inserted into both sides of the contact pattern arranged in a zigzag form, but the auxiliary patterns having different lengths are used together.

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

5 is a view schematically showing a state of a contact hole pattern formed in a mask for lithography according to the present invention.

The mask for lithography cannot expose the exposure light source to the surface of the mask substrate 100 formed of a transmissive material (for example, silicon dioxide (SiO ₂ )) through which the exposure light source used in the photolithography process can pass. The light shielding pattern 200 formed of a non-transmissive material (for example, chromium (Cr)) may be formed and manufactured. Here, the plurality of regions in which the light blocking pattern 200 is not formed on the mask substrate 100 becomes the light transmitting pattern 300.

The light transmission pattern 300 includes a contact pattern 310 and auxiliary patterns 320 and 330 formed on both sides of the contact pattern 310.

The contact pattern 310 may be a drain contact pattern, and the drain contact pattern is formed in a zigzag form so that the centers thereof are alternate with each other. As the adjacent contact patterns are staggered with each other, the centers of the patterns, which are the portions where the incident light is most concentrated during the lithography process, are staggered with each other, thereby increasing the process margin for forming the contact pattern 310.

The auxiliary patterns 320 and 330 are patterns formed at both sides of the contact pattern 310 to improve the intensity of the light with respect to the contact pattern 310 by using the interference phenomenon of light, and have different lengths. The patterns are used together. For example, a first auxiliary pattern 320 having a short length and a second auxiliary pattern 330 having a much longer length than the first auxiliary pattern 320 are used together. Preferably, the second auxiliary pattern 330 is formed to be inserted between the first auxiliary pattern 320 and the contact pattern 310. In this case, the second auxiliary pattern 330 is formed such that a plurality of line patterns having a length corresponding to a predetermined number of contact patterns 310 are arranged in a line or one line having a length corresponding to the entire contact pattern 310. It can be formed in a pattern.

Short auxiliary patterns can improve the light intensity for the contact pattern 310 at a specific location, but because of the short length of the pattern, there is a difference in the critical dimension (mask error) between the auxiliary patterns when fabricating the actual mask. It is likely to occur. CD differences between auxiliary patterns can produce different results than expected in the design. Therefore, the present invention uses the short length auxiliary pattern 320 and the long length auxiliary pattern 330 together. In such an embodiment, as shown in FIG. 5, the first auxiliary pattern having the short length and the contact pattern 310 may be used. The second auxiliary pattern 330 having a long length is inserted between the patterns 320 to reduce the influence of the mask error caused by the first auxiliary pattern 320, thereby increasing the intensity of light on the contact pattern 310. .

The length between the contact pattern 310 and the first auxiliary pattern 320 and the length between the first auxiliary pattern 320 and the second auxiliary pattern 330 can be freely adjusted within the acceptable range of the lithographic apparatus.

6A and 6B are cross-sectional views illustrating a method of manufacturing a contact hole of a semiconductor device using a mask for lithography according to the present invention.

Referring to FIG. 6A, an active region is defined by forming a plurality of device isolation layers 402 parallel to each other in a predetermined region of a semiconductor substrate 400 including a cell region and a peripheral circuit region. The cell region is composed of a plurality of strings, and each string is formed such that a source select transistor (not shown), a plurality of memory cells (not shown), and a drain select transistor (not shown) are connected in series. Peripheral transistors are formed in the peripheral circuit region.

An ion implantation process is performed on the entire structure including the transistor and the memory cells to form a source region (not shown) on the semiconductor substrate 400 on one side of the source select transistor, and to drain the semiconductor substrate 400 on the side of the drain select transistor. Region 404 is formed. In addition, a junction region (not shown) is formed between the memory cells.

In this case, since the contact pattern 310 defining the drain contact region is formed in a zigzag shape, the drain regions 404 in FIG. 6A are not formed continuously but alternately one by one.

Next, an etch stop layer 405 and a first insulating layer 406a are formed on the semiconductor substrate 400 on which the source region, the junction region and the drain region 404 are formed, and the first insulating layer 406a is etched to form a source contact. A hole (not shown) is formed. The first insulating film 406a is preferably formed of an oxide film. Next, after forming a conductive material in the source contact hole, a planarization process such as a chemical mechanical polishing (CMP) method is performed to form a source contact plug (not shown).

Next, a second insulating film 406b, a hard mask layer 408, and a photoresist film (not shown) are sequentially formed on the first insulating film 406a including the source contact plug. In this case, an etch stop layer may be additionally formed under the hard mask layer 408.

Next, the photosensitive film is patterned by performing the photolithography process using the mask for lithography of FIG. 5 to form the photosensitive film pattern 410.

In this case, in the lithographic mask of the present invention, as described above, the second auxiliary pattern 330, which is a long line pattern, is formed between the drain contact pattern 310 and the first auxiliary pattern 320. Even if the CD difference occurs between the patterns 320, the influence of the mask error is minimized by the second auxiliary pattern 330, thereby increasing the intensity of light on the contact pattern 310.

FIG. 7 is a view illustrating a drain contact formed using a lithography mask in which auxiliary patterns 320 and 330 of different lengths are formed as shown in FIG. 5, and a depth of focus (DOF) is 150 nm and an EL ( Exposure Latitude) is 12.9%, which satisfies DoF (> 150 nm) and EL (> 12%) required for mass production.

Next, referring to FIG. 6B, the hard mask layer 408 is etched using the photoresist pattern 410 as an etch mask to form the hard mask pattern 408a, and then the photoresist pattern 410 is removed.

Subsequently, the second insulating layer 406b, the first insulating layer 406a, and the etch stop layer 405 are sequentially selected and etched to expose the drain region 404 using the hard mask pattern 408a as an etching mask to form a drain contact hole. Form.

Thereafter, although not shown in the drawings, a conductive material is embedded in the drain contact hole to form a contact plug electrically connected to the drain region 404.

In FIG. 5, the first auxiliary pattern 320 is formed in the form of a line pattern extending in the length (long axis) direction of the second auxiliary pattern 330, but the present invention is not limited thereto. For example, the first auxiliary pattern 320 may be formed in a dot shape or may be formed in a line pattern extending in a short direction of the second auxiliary pattern 330. In addition, the auxiliary pattern as in the present invention can be applied even when the contact patterns are formed in a line rather than in a zigzag form. When the contact patterns are formed in a row, the auxiliary patterns may be formed on only one side of the contact pattern without forming them on both sides of the contact pattern.

In the above-described embodiment, the semiconductor device of the present invention is a flash memory, but is not limited thereto. That is, the present invention can be applied to the case of forming a mask pattern used for manufacturing other types of semiconductor devices. In addition, the present invention may also be applied when forming a dense contact or dummy pattern.

It will be apparent to those skilled in the art that various modifications, additions, and substitutions are possible, and that various modifications, additions and substitutions are possible, within the spirit and scope of the appended claims. As shown in Fig.

1A shows the appearance of a conventional lithographic mask for forming a drain contact applied to a flash memory.

FIG. 1B shows a drain contact pattern formed using the lithographic mask of FIG. 1A. FIG.

FIG. 2 shows the appearance of a bridge-generated contact when formed using the lithographic mask of FIG.

3 is a view showing a conventional lithographic mask in which a drain contact is formed in a zigzag form.

Fig. 4 shows that the drain contact formed using a conventional mask for lithography does not satisfy DoF (> 150 nm) and EL (> 12%) required for mass production.

5 is a view schematically showing a state of a contact hole pattern formed in a mask for lithography according to the present invention.

6A and 6B are cross-sectional views illustrating a method of manufacturing a contact hole in a semiconductor device using a mask for lithography according to the present invention.

FIG. 7 shows that a drain contact formed using the mask for lithography of FIG. 5 satisfies DoF and EL required for mass production.

Claims (8)

A mask substrate; A light blocking pattern formed on the mask substrate; And And a light transmitting pattern defined by the light blocking pattern and having a plurality of auxiliary patterns formed at different lengths on at least one side of the contact pattern. The method of claim 1, wherein the contact pattern is Lithographic mask, characterized in that the drain contact pattern formed in a zigzag form. The method of claim 2, wherein the auxiliary pattern A mask for lithography, characterized in that formed on both sides of the contact pattern. The method of claim 1, wherein the auxiliary pattern A first auxiliary pattern; And And a second auxiliary pattern having a length longer than that of the first auxiliary pattern and formed between the first auxiliary pattern and the contact pattern. The method of claim 4, wherein the first auxiliary pattern And a line pattern extending in the major axis direction of the second auxiliary pattern or in the minor axis direction of the second auxiliary pattern. The method of claim 4, wherein the first auxiliary pattern A mask for lithography, characterized in that it is a dot pattern. The method of claim 4, wherein the second auxiliary pattern And a plurality of line patterns having a length corresponding to a predetermined number of contact patterns are arranged in a line. The method of claim 4, wherein the second auxiliary pattern A mask for lithography, characterized in that formed in one line pattern having a length corresponding to the entire contact pattern.

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