KR20090099862A - The exposure mask and the method for manufacturing flash memory devices using the same - Google Patents

Abstract

PURPOSE: An exposure mask and a method for manufacturing flash memory devices using the same are provided to make a pitch variation region of a flash memory page buffer at the flash memory device linear. CONSTITUTION: In an exposure mask, a line pattern between a cell region and a pager buffer is composed of a unit pattern of a planar structure in which it has a step change. A method of manufacturing of the flash memory device is comprised of the steps: the exposure mask is prepared; a photosensitive film is formed on the semiconductor substrate; the photolithograph pattern is formed by developing a photolithograph film with the exposure mask; and a line pattern is formed by etching the photosensitive pattern with etching mask.

Description

Exposure mask and the method for manufacturing flash memory devices using the same

The present invention relates to an exposure mask and a method of forming a flash memory device using the same, and in particular, in forming a pattern of a flash memory device, a pattern can be stably formed in a pitch change section of a page buffer area, thereby over-compensation and mask size. The present invention relates to an exposure mask and a method of forming a flash memory device using the same, which can reduce a difference between equipments, thereby securing a process margin.

Among the semiconductor devices, flash memory is a nonvolatile memory whose data does not disappear even when the power supply is cut off. Currently, active research on high integration is being conducted to develop a large memory device capable of storing a large amount of data.

In order to further improve the density of the flash memory, development of a multi level cell, which is a multiple bit cell capable of storing a plurality of data in one memory cell, has been made.

The multilevel cell has a page buffer area connected to a bit line in the cell array area to read data stored in the memory cell array area.

Unlike the patterns in the cell array region, patterns such as power lines and contact plugs exist in the page buffer region, so that the patterns are formed in a form of being bent in a region where additional patterns exist without having a linear pattern as in the cell array region. do.

1 is a diagram illustrating a pattern pitch change section in a conventional page buffer region, and FIG. 2 is an electron scanning micrograph of a pattern pitch change section in a conventional page buffer region.

In this case, the pitch represents the distance from one side of the bit line to one side of the next bit line, that is, the sum of the width of the bit line and the distance between the next bit line.

1 and 2, it can be seen that spaces and lines are not formed at regular intervals due to a sudden pattern change in the pattern pitch change period.

In a section where the pattern is rapidly changed in the pitch change section as described above, the bending phenomenon becomes more severe. In this case, the line width of the bending section becomes narrower, making it difficult to implement the pattern on the wafer and making a mask.

In addition, in a section in which the pitch is suddenly changed, the ratio between the line width and the space interval is not constant, which may cause a problem in pattern formation due to a change in the open layout.

In order to improve the above problem, the length of the section where the pitch is changed is extended to 10 µm or more to form a pattern in a nearly straight line, but it is impossible to process the optical proximity correction (OPC) of the pattern of the section of 10 µm or more. In addition, since mask modification is inevitable, there is a big problem in terms of cost.

The present invention is to solve the problem that there is a limit in forming a pattern in the difficulty of the pattern implementation and the mask fabrication because the pattern is formed in the form of bending in a section in which the pitch of the flash memory device is changed in the semiconductor device To provide an exposure mask and a method of forming a flash memory device using the same to increase the accuracy of the pattern formation by arranging the pattern in a straight line in the pitch change period.

The exposure mask of the present invention is characterized in that the line pattern of the pitch change section located between the cell array region and the page buffer region is divided into unit patterns.

In this case, the line pattern is characterized in that the bit line pattern.

The unit pattern may have a planar structure having a sequential step change with a size greater than 0 and less than 1/20 of the pitch of the page buffer area.

In addition, the unit pattern is an exposure mask, characterized in that formed in a square or rectangular planar structure.

The method of forming a flash memory device of the present invention comprises the steps of preparing the exposure mask of claim 1, forming a photoresist film on a semiconductor substrate, and exposing and developing the photoresist film using the exposure mask to form a photoresist pattern; And forming a line pattern by using the photoresist pattern as an etching mask.

In this case, the line pattern is characterized in that the bit line pattern.

The present invention has an advantage of making the pattern implementation in the page buffer area stable and making the mask stable by almost straightening the pitch change section of the flash memory page buffer area in the flash memory device so that the pitch change period of the flash memory page buffer area is not changed drastically.

In addition, there is an advantage that can improve the process yield by securing a process margin.

In the present invention, in order to form a pattern in a straight line without a sudden pattern change in the pitch change period in which the pattern pitch of the flash memory device is changed, it is arranged in a unit pattern so that the pattern can be implemented stably.

In particular, the pitch change period in the flash memory device is a bit line is pushed out because a pattern different from the pattern in the cell array, that is, a power line, exists in the page buffer area, so that the pitch of the bit line in the cell array and the page buffer area are different. It is formed so that the pitch of is different.

In this case, it is most preferable that the pitch change section is a straight line. The pitch change section is divided into a pattern having a small size of a rectangular shape (hereinafter, referred to as a unit pattern) and the bit line of the cell array region. By arranging the bit lines of the page buffer area to be connected, they are arranged in a pattern similar to a straight line.

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

3 is a plan view showing a pattern pitch change interval of a page buffer region formed by the technique of the present invention, where P1 is a bit line pitch in a cell array, P2 is a bit line pitch of a page buffer region, and W1 is a pitch change interval Is the width of the unit pattern, L1 is the length of the unit pattern of the pitch change section, and H is the step change of the unit pattern.

4 is an electron scanning micrograph showing a pattern pitch change section of a page buffer area formed by the technique of the present invention.

As shown in FIG. 3, the pitch change period of the page buffer area is arranged in a unit pattern connecting bit lines of the cell array area and bit lines of the page buffer area.

At this time, it is preferable that the arrangement and size of the unit pattern satisfy the following conditions.

First, in detail about the arrangement of the unit pattern, since the cell array area and the page buffer area have bit lines of different pitches, it is desirable to allow the cell array area and the page buffer area to be arranged in a straight line shape rather than a sudden pattern change shape in the pitch change period. Do.

In addition, in order to reduce the amount of change in the pattern in order to maintain the shape of the straight line in the arrangement of the unit pattern, it is preferable to minimize the change in the unit pattern step (H).

In order to connect the bit lines formed in the cell array region and the bit lines formed in the page buffer region, the bit lines formed in the cell array region are moved by the unit pattern step variation H in the unit pattern line width W1 direction.

At this time, it is preferable that the unit pattern step variation H is greater than 0 and less than 1/20 of the page buffer area pitch P2.

Next, when the size of the unit pattern is examined in detail, it is divided into small enough to express the shape of a straight line in the pitch change section. The length L1 of the unit pattern is a pitch of an area adjacent to the area where the pitch has started to change, eg, For example, it is preferable to set it as 1/2 of the pitch P1 of the cell array area or the pitch P2 of the page buffer area.

Therefore, the unit pattern is most preferably formed in a square or rectangular planar structure.

The photograph of the pitch change section formed by the above method as an electron scanning microscope is shown in FIG. 4. Unlike the conventional pitch change section of FIG. 2, the space and the line are constantly formed and the pitch change section is almost straight. You can see that it is connected in the form.

In particular, the method of forming a semiconductor device using the exposure mask of the present invention is not only applied to the page buffer area of the flash product, but also to the pattern of the semiconductor device such as DRAM, PRAM, etc., which is applied to all areas whose pitch is changed. Can be.

1 is a diagram showing a pattern pitch change section in a conventional page buffer area.

2 is a scanning microscope photograph of a pattern pitch change section of a conventional page buffer region.

Fig. 3 is a plan view showing a pattern pitch change section of a page buffer area formed by the technique of the present invention.

4 is an electron scanning microscope photograph showing a pattern pitch change section of a page buffer area formed by the technique of the present invention.

Claims (7)

An exposure mask, wherein the line pattern of the pitch change section located between the cell array region and the page buffer region is divided into a unit pattern of a planar structure having a step change. The exposure mask of claim 1, wherein the unit pattern has a length of 1/2 of the line pattern pitch. The exposure mask of claim 1, wherein the step variation of the unit pattern is greater than 0 and less than 1/20 of a pitch of the page buffer area. The exposure mask of claim 1, wherein the line pattern is a bit line pattern. The exposure mask of claim 1, wherein the unit pattern has a square or rectangular planar structure. Preparing an exposure mask of claim 1; Forming a photoresist film on the semiconductor substrate; Exposing and developing a photoresist film using the exposure mask to form a photoresist pattern; And And forming a line pattern by using the photoresist pattern as an etching mask. The method of claim 6, wherein the line pattern is a bit line pattern.

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