JPH02134633A - Formation of photomask and pattern - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a photomask and pattern forming method used in the manufacture of semiconductor integrated circuits.

"Summary of the Invention" The present invention provides a photomask that uses a plurality of masks and partially overlaps each other to form a connection pattern. Even if the amount of overlap between masks changes, the dimensional change in pattern width is kept small.

[Prior Art] In recent years, as semiconductor devices have become more highly integrated, there has been a tendency for integrated circuit depths to become larger in order to include many circuit elements. For this reason, a foot mask for forming a pattern on one depth consists of two or more masks divided into serums (field size) that can be transferred with -2 exposure, as shown in Figure 6. There is. In addition, FIG. 6 (■) is a plan view conceptually showing the shape of a conventional photomask and its usage condition.
are masks formed to the field size, and by overlapping each other at the tip portions 1a and 2a of the patterns, a continuous mask pattern can be formed across both masks. There is.

[Problem to be solved by the invention] However, in such a conventional example, for example, two
Connect the mask pattern over two areas, and
When a and 2a are not laterally shifted and light is irradiated in the same direction as during exposure, the simulation result of the light intensity distribution is as shown in FIG. That is, as shown in the figure, there is a problem in that the width W1 of the positive resist to be exposed becomes narrow to W at the overlapped portion of the mask. Note that when this distance is 0.5 μm, W is narrowed to about 0.4 μm.

In addition, if there is a lateral shift in the overlapping parts of the masks, as shown in Figure 8, the width of the renost will be significantly reduced in the molded part, and the renost will be cut at the overlapped part. There was a problem.

In particular, when the storage capacity of DRAM, which is a typical example of miniaturization and high integration, increases by four times, it is necessary to make narrow grooves in the resist or to ensure that narrow resist remains. will be the biggest challenge.

The present invention has been devised by focusing on these conventional problems, and provides a photomask and pattern forming method that suppresses changes in pattern width even when the amount of overlap between masks changes. I am trying to get it.

[Means for Solving the Problems] Accordingly, the present invention provides a photomask in which a connection pattern is formed by partially overlapping the masks using a plurality of masks, in which the mask pattern in the overlapped portion is made narrower. The solution is to create a shape.

[Function] Since the width of the overlapping area between the masks is narrow, the light intensity distribution in this overlapping area does not widen. For example, if a positive resist is used, this narrowing of the resist width can be prevented.
Yu can do it. Furthermore, since there is no lateral shift in the overlapping portion, and similarly, there is no bulge in the light intensity distribution, an accurate pattern can be formed.

[Example] Hereinafter, details of the photomask according to the present invention will be described based on an example shown in the drawings.

In the figure, reference numerals 1 and 2 denote masks each formed to the field size, and by overlapping the pattern ends IΔ and 2A with each other, both masks l.

Two consecutive mask patterns can be formed. As shown in FIG. 2, this end portion IA is formed to have a narrow width by providing a two-step stepped portion al+12 toward the tip. In this end IA, the length W that becomes narrower on the negative side edge side is set to a length of 115 to 1/2 of the wavelength λ of the light used for exposure, that is, in the range of 115 to 1/2 λ. . Further, the end portion 2A of the mask 2 is also formed in the same manner.

The end portion IA2A of the mask 1.2 formed in this way is shown in FIG. A simulation result of the light intensity distribution as shown in the figure is obtained.As can be seen from the figure, there is no dimensional variation or change in shape at the joints between the masks, and a resist pattern can be reliably formed. I can do it.

Furthermore, when the end portions IA and 2A of the mask 1.2 are slightly shifted in the width direction and overlapped and irradiated with light, a simulation result of the light intensity distribution as shown in FIG. 5 is obtained. Even if lateral misalignment occurs between masks in this way, it is possible to suppress the dimensional variation to a small level and prevent the exposed Renost pattern from becoming narrow.

Although the embodiment has been described above, various other design changes are possible. For example, as shown in FIG. Of course you can.

In this case, if W in the figure is set to 115 to 1/2 of the wavelength λ of the light used for exposure, as in the above embodiment, dimensional fluctuations and shape changes can be reliably prevented.

Although the above embodiment has been explained using a simple mask pattern, it goes without saying that it can be applied to various mask patterns.

[Effects of the Invention] As is clear from the above description, according to the photomask pattern forming method according to the present invention, even if the amount of mask overlap changes, the dimensional change of the pattern can be suppressed to a small level, and This has the effect of suppressing variations in pattern size and shape even if lateral misalignment occurs between masks.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing how the photomask according to the present invention is used, FIG. 2 is an enlarged view of the edge of the mask, FIG. 3 is an enlarged view showing a modified example of the photomask, and FIG. A light intensity distribution diagram when there is no lateral deviation between the edges of the mask, Figure 5 is a light intensity distribution diagram when there is lateral displacement between the edges of the same photomask, and Figure 6 shows a conventional photomask. Plan view,
FIG. 7 is a light intensity distribution diagram when there is no lateral deviation between the ends of a conventional photomask, and FIG. 8 is a light intensity distribution diagram when there is lateral deviation between the ends of the same photomask. 1.2... Photomask, IA 2A... End. $45! ll'l's 7x door Z71tI84 shakusen 1st
Figure 4: 7 strong pans when there is no discrepancy Figure 1: Person JL Form Tsu 511 Figure 3: Loss of money, stupidity Light intensity in case 1 Figure 7 Sub-f- Example Figure 6 Lateral slippage Mask and pattern formation method 3, relationship with the case of the person making the correction

Claims (2)

[Claims] (1) A photomask in which a connection pattern is formed by partially overlapping the masks using a plurality of masks, characterized in that the mask pattern in the portion where the masks overlap has a narrow shape. (2) In a pattern forming method in which a connection pattern is formed by partially overlapping the masks using a plurality of masks,
A pattern forming method characterized by using a photomask in which the overlapping portion has a narrow shape.