JPH09106062A - Exposure mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form more precise device patterns even for hole patterns by arranging phase shifters in optimum. SOLUTION: An exposure mask has island-shaped light transmissive parts cyclically arranged and light shading parts surrounding them. The light transmissive parts are accumulated electrode contact patters for DRAM cells of a 1/4 pitch array type, in which phase shifter layers are continuously formed in plural patterns on one (B, C) with respect to a pair of patterns A-B and A-C minimize a distance between an arbitrary light transmissive pattern A and a light transmissive pattern located around the pattern A, so that each other neighboring patterns where a distance between the patterns is minimized can be is opposite phase and each other neighboring patterns where a distance between the patterns is not minimized can be in the same phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure mask that utilizes a phase shift effect, and more particularly to an exposure mask that has an improved phase shifter arrangement method.

[0002]

2. Description of the Related Art In recent years, the miniaturization of semiconductor circuit elements has been rapidly progressing, and the minimum dimension of the element is finally reaching the region below the wavelength of light. For example, G-bit DRA
It is considered that a lithography technique having a resolution of 0.15 μm or less is required to realize the M device,
As a method of achieving such resolution with a sufficient depth of focus, a phase difference is given to the light passing through the photomask,
The so-called phase shift technique for improving the light intensity profile has received attention.

Although various methods have been proposed for the phase shift method, the most effective method is the spatial frequency modulation method proposed by Levenson et al. (MCLevenson).
Others, “Improving Resolution Photolithography with a
Phase-shifting Mask ”.IEEE Transactions on Elect
ron Devices., Vol.ED-29, No.12, Dec., 1982, P1828-1836
Such).

The principle of the Levenson method is shown in FIG. 15 in comparison with the conventional method. (A) is a conventional method and (b) is a Levenson method. In the Levenson method, by arranging a phase shifter in one of the openings adjacent to each other on the photomask, the phase of light passing through the openings adjacent to each other is shifted by 180 degrees, and the interference of the light is used to transmit the light of the transmitted light. Sharpens the intensity profile. Since the light passing through the adjacent opening is used as described above, it is extremely effective for a simple line-and-space pattern or a checkered pattern as shown in FIG.

However, since the pattern shape for forming each layer of the actual device is more complicated, it is necessary to devise the arrangement of the phase shifter. In particular, for example DR
It is difficult to apply the Levenson-type phase shift method to the hole patterns such as the storage electrode contact and the bit line contact in the AM cell because the arrangements are more isolated and scattered.

[0006]

As described above, conventionally, it is difficult to obtain a desired device pattern with the Levenson type phase shifter arrangement, and it is particularly effective to apply the phase shift method to the hole pattern. Was difficult.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an exposure that enables formation of a more precise device pattern even for a hole pattern by an optimum phase shifter arrangement. Is to provide a mask for use.

[0008]

[Means for Solving the Problems]

(Structure) In order to solve the above problem, the present invention employs the following structure. That is, the present invention (claim 1)
In an exposure mask having an island-shaped light-transmitting portion arranged periodically and a light-shielding portion surrounding the island-like light-transmitting portion, a distance between an arbitrary light-transmitting portion pattern and a light-transmitting portion pattern located around the pattern is The phase shifter layer is formed on either one of the pair of patterns that has the minimum distance, and the adjacent pattern with the minimum distance between patterns has the opposite phase, and the adjacent pattern with the minimum distance between patterns has the same phase. The phase shifter layer is continuously formed in a plurality of patterns.

Here, preferred embodiments of the present invention include the following. (1) The phase shifter layer shifts the phase of transmitted light by 180 degrees,
The phase of the adjacent pattern should be reversed. (2) The pattern of the light transmitting portion should be the contact hole pattern of the DRAM arranged in the 1/2 pitch array system. (3) The pattern of the light transmitting part should be the contact hole pattern of the DRAM arranged in the 1/3 pitch array system. (4) The pattern of the light transmitting portion should be the contact hole pattern of the DRAM arranged in the 1/4 pitch array method.

Further, according to the present invention (claim 3), in an exposure mask having an island-shaped light transmitting portion periodically arranged and a light shielding portion surrounding the light transmitting portion, an arbitrary light transmitting portion pattern and a pattern of the pattern are formed. It is characterized in that the phase shifter layer is formed on either one of the pair of patterns such that the geometrical barycentric position intervals of the pattern groups located in the periphery are minimized.

Further, according to the present invention (claim 4), in an exposure mask having an island-shaped light transmitting portion pattern periodically arranged and a light shielding portion surrounding the island light transmitting portion pattern, an arbitrary underlying wiring layer is provided. The phase shifter layers are arranged so that the light transmitted through the pair of patterns facing each other with the wiring layer in between has the same phase, and the light transmitted through the pattern pair located on the same side with respect to the wiring layer has the opposite phase. Is characterized by.

The following are preferred embodiments of the present invention. (1) The pattern of the light transmission part should be the pattern of contact holes. (2) The underlying wiring layer should be a line-and-space pattern formed periodically, for example, a bit line. The contact hole should be connected to the bit line. (3) The underlying wiring layer is a line-and-space pattern formed periodically, for example, a word line. Contact holes must be self-aligned with the word lines. (4) Both patterns connected to the same element region have the same phase and opposite phases to the patterns connected to the adjacent element regions.

Further, according to the present invention (claim 5), in an exposure mask having an island-shaped light transmitting portion which is periodically arranged and a light shielding portion surrounding the light transmitting portion, the light transmitting portion forms a hole pattern. The light transmitted through a series of hole patterns connected to the same island-shaped ground pattern has the same phase, and the light transmitted through a series of hole patterns connected to different island-shaped ground patterns adjacent to each other has an opposite phase. The phase shifter layer is arranged so that

Further, according to the present invention (claim 6), in an exposure mask having a plurality of island-shaped light transmitting portions and a light shielding portion surrounding the light transmitting portions, the light transmitting portions form a hole pattern. , The phase shifter layer is arranged so that the light transmitted through the series of hole patterns connected to the same terminal has the same phase, and the light transmitted through the series of hole patterns connected to the adjacent different terminals has the opposite phase. It is characterized by having done. The plurality of arrangements may be random arrangements or periodic arrangements. (Operation) According to the present invention (Claim 1), one of the pair of patterns that minimizes the distance between the arbitrary light transmitting portion pattern and the light transmitting portion pattern positioned around the pattern. By forming the phase shifter layer on, the light intensity profile of the pattern arranged at the minimum interval can be sharpened. For example, if this arranging method is applied to a contact hole pattern of a DRAM, it becomes possible to form a fine contact hole. Forming the phase shifter by continuously forming the phase shifter layers with a plurality of patterns so that the adjacent pattern with the smallest inter-pattern distance has the opposite phase and the adjacent pattern with the smallest inter-pattern distance has the same phase. Lithography is easy.

Further, according to the present invention (claim 4), the light transmitted through the pair of patterns facing each other with the wiring layer in between has the same phase with respect to an arbitrary underlying wiring layer, and the same with respect to the wiring layer. By arranging the phase shifter so that the light transmitted through the pattern pair located on the side is in opposite phase, the pattern separation margin across the wiring layer is narrowed, but holes are formed in self-alignment with the wiring layer. By doing so, the problem of short circuit between holes can be avoided.

Further, according to the present invention (claim 5), the light transmitted through a series of hole patterns connected to the same island-shaped underlayer pattern has the same phase and is adjacently connected to different island-shaped underlayer patterns. By arranging the phase shifter layer so that the light transmitted through the series of hole patterns described above has the opposite phase, it is possible to surely separate the adjacent hole patterns.

According to the present invention (claim 6), light passing through a series of hole patterns connected to the same terminal has the same phase, and a series of hole patterns connected to different terminals adjacent to each other. By arranging the phase shifter layers so that the transmitted lights have opposite phases, hole patterns connected to different terminals (wiring) can be reliably separated.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the illustrated embodiments. (First Embodiment) FIG. 1A is for explaining an exposure mask according to the first embodiment of the present invention.
It is shown that a phase shifter is arranged in a storage electrode contact pattern of a / 4 pitch array type DRAM cell. In the figure, 10 is a pattern of the light transmitting portion, and hatched portion 11 is a shifter arranging portion. The phase shifter
The phase of the transmitted light is shifted by 180 degrees and the phase of the adjacent pattern is reversed.

In the present embodiment, the phase shifter is formed on either one of the pair of hole patterns such that the distance between the arbitrary hole pattern and the hole patterns located around the pattern is minimized.

Specifically, for example, the pattern A faces the patterns B and C at the shortest distance x, and the light passing through the patterns B and C has an opposite phase to the light passing through the pattern A. Further, the phase shifters are arranged in the patterns B and C. Further, the phase shifter is arranged so that the pattern adjacent to the lower left side of the pattern A (not the shortest distance) is in phase, and the pattern adjacent to the upper right side of the patterns B and C (not the shortest distance) is in phase. doing.

According to the shifter arrangement shown in FIG. 1A, the patterns which are closest to each other are always arranged in opposite phases, so that the light intensity profile of the pattern can be sharpened, and the fine hole patterns are separated from each other. It will be possible.

FIG. 1B shows a modified application example of the phase shifter shape. The phase shifters may be formed in the individual hole patterns as shown in FIG. 1A, but may be arranged in the entire in-phase region as shown in FIG. 1B. By doing so, the area of one phase shifter becomes large and the number thereof becomes small, and as a result, lithography for forming the phase shifter becomes easy.

As described above, according to this embodiment, it is possible to realize a sufficient resolution and a sufficient depth of focus even for a device pattern such as a contact hole for which it is difficult to apply a phase shift mask. As a result, a semiconductor device with higher density and higher performance can be realized. Also, by applying a phase shift mask, the performance of the exposure apparatus can be brought out to the limit, so that it becomes possible to manufacture using a cheaper apparatus, and a high-density and high-performance semiconductor device can be manufactured at a low cost. Can be realized. (Second Embodiment) FIG. 2A shows a state in which a phase shifter is arranged in a bit line contact pattern of a 1/4 pitch array type DRAM cell. The pattern D faces the patterns E and F at the shortest distance y, and the patterns E and F
The phase shifter is arranged in the pattern D so that the light passing through the pattern D has an opposite phase with respect to the light passing through.

FIG. 2B shows a modified application example of the phase shifter arrangement, in which the patterns facing each other at the shortest distance are made to have opposite phases, and the same line is made to have the same phase. (Third Embodiment) FIG. 3 shows how a phase shifter is arranged in a storage electrode contact pattern of a 1/2 pitch array type DRAM cell. Patterns H and I and shortest distance x
A phase shifter is arranged in the pattern G so that the lights passing through the pattern G facing each other have the opposite phase. Since the distance z between the patterns K and J is sufficiently large, the phases may be the same. Also in this case, since the same line has the same phase, the phase shifter can be easily arranged. (Fourth Embodiment) FIG. 4A is for explaining an exposure mask according to a fourth embodiment of the present invention.
It shows that a phase shifter is arranged in a trench capacitor pattern of a 1/2 pitch array type DRAM cell. The phase shifter is arranged in the pattern L so that the patterns L, M, N, and O have the center-of-gravity position interval of the pattern LM having the shortest distance x in the opposite phase. Pattern L-N,
Since the distance z between the centers of gravity with L-O is z> x, they may be in phase. Here, since the patterns adjacent to each other in the left-right direction at the center-to-center distance z instead of the shortest distance have the same phase, the phase shifter can be continuously formed every two columns. In this case, since the phase shifter can be continuously formed with a plurality of patterns, the phase shifter can be easily arranged.

FIG. 4B shows a modified application example of the phase shifter arrangement, in which the adjacent patterns with the distance z between the centers of gravity also have opposite phases. (Fifth Embodiment) FIG. 5A shows a state in which a phase shifter is arranged in a storage electrode contact pattern of a 1/3 pitch array type DRAM cell. A phase shifter is arranged in the pattern P so that the lights passing through the patterns P and Q facing each other at the shortest distance x have opposite phases. Also in this case, since the patterns adjacent to each other at the interval which is not the shortest distance have the same phase, there is an advantage that the phase shifter can be easily arranged.

FIG. 5B shows a modified application example of the phase shifter arrangement. Further, FIG. 6 is also a modification application example of the phase shifter arrangement. (Sixth Embodiment) FIG. 7 shows a phase shifter arranged in the bit line contact pattern of a 1/3 pitch array type DRAM cell. A phase shifter is arranged in the pattern R so that the light passing through the pattern RS facing each other at the shortest distance x and further the light passing through the pattern RT have opposite phases. (Seventh Embodiment) FIG. 8A is for explaining an exposure mask according to the seventh embodiment of the present invention.
It is shown that a phase shifter is arranged in a storage electrode pattern of a / 4 pitch array type DRAM cell.

In this embodiment, the bit line 1 which is the base wiring is used.
The separation of the adjacent patterns V and W on the same side of the bit line 12 is prioritized over the patterns V and U sandwiched between the two. In other words, for example, the patterns U, P are arranged so that the light transmitted through the pattern pairs facing each other with the bit line 12 in between has the same phase, and the light transmitted through the pattern pairs located on the same side with respect to the bit line 12 has the opposite phase. A phase shifter is arranged at V.

In this case, the patterns U and V facing each other with the bit line 12 in between have the same phase, but even when the separation between these is incomplete, holes are formed on the bit line 12 by themselves. By performing them in a consistent manner, it is possible to avoid a short circuit between the patterns U and V.

FIG. 8B is a modification application example of the phase shifter arrangement, in which the same column has the same phase. 9 is a modification of FIG. 8, FIG. 9 (a) is a combination of patterns U and V in FIG. 8 (a), and FIG. 9 (b) is a combination of patterns U and V in FIG. 8 (b). It was done. By connecting the patterns in this manner, the phase shifter can be easily arranged. (Eighth Embodiment) FIG. 10A is for explaining an exposure mask according to an eighth embodiment of the present invention.
The figure shows a state in which phase shifters are arranged in a hole pattern for forming a buried plug of a 1/2 pitch array type DRAM cell.

In this embodiment, the patterns connected to the same element region have the same phase, and the patterns connected to the adjacent element regions have the opposite phase. further,
The patterns arranged adjacent to each other by being sandwiched by the gate electrodes as the underlying wiring have the same phase, and the adjacent patterns on the same side of the gate electrode have the opposite phase.

Specifically, the phase shifters are arranged in the patterns 31, 32, 33 connected to the same element region 30, and the patterns 41, 42, 43 connected to the adjacent element regions 40. The phase is opposite to the pattern group.

By using such a shifter arrangement, it is possible to avoid a defect that the embedded plug is short-circuited between different element regions. The patterns 31, 32, and 33 connected to one element region 30 have the same phase, but as shown in FIG. 10B, holes are formed in self-alignment with the gate electrode (word line) 50. By doing this, it is possible to avoid a short circuit between holes.

FIG. 11A is a modified example of FIG. 10A. It is also possible to connect the patterns 31, 32, 33 and the like in FIG. 10A and form the phase shifter in an inverted T-shaped pattern. It is possible. In this case, since the area of one phase shifter is large and the number thereof is small, lithography for forming the phase shifter becomes easy.

FIG. 11B is a modification of FIG. 11A, in which a part of the inverted T-shaped pattern is extended. (Ninth Embodiment) FIG. 12A is for explaining an exposure mask according to a ninth embodiment of the present invention.
The figure shows a phase shifter arranged in a hole pattern for forming a buried plug of a 1/3 pitch array type DRAM cell.

In this embodiment, the light transmitted through the series of hole patterns connected to the same element region pattern has the same phase, and the light transmitted through the series of hole patterns connected to different element region patterns adjacent to each other has the same phase. The phase shifters are arranged so as to have opposite phases.

FIG. 12B is a modified application example of the phase shifter arrangement. Although a series of hole patterns connected to the same element region pattern have the same phase as in FIG. 12A, The adjacent element region patterns have the same phase in the line direction and opposite phase in the column direction. in this case,
Although there is a disadvantage in separating the hole pattern between the adjacent element regions in the line direction, there is an advantage that the phase shifter can be easily arranged. (Tenth Embodiment) FIG. 13 shows an embodiment in which a phase shifter is arranged in a contact hole pattern for the underlying wirings 71 to 75. Phase shifters are arranged so that the transmitted light has the same phase for each pattern connected to the same terminal (wiring), and the phase is opposite to that of the contact pattern group connected to the adjacent terminal (wiring). ing.

This embodiment is an example in which the separation of contact holes connected to different terminals is prioritized, and this shifter arrangement makes it possible to avoid a short circuit between wirings via the contact holes. Although the contact patterns connected to the same terminal have the same phase, even if the separation between these holes is incomplete, the connected terminals have the same voltage, which causes any problem. There is no such thing.

The present invention is not limited to the above embodiments. The method of arranging the phase shifter shown in the embodiment has a meaning in the relative positional relationship with the device pattern, and is not limited to the layer shown in the embodiment. Further, the remaining pattern can be formed by combining the negative resist with the mask having the island-shaped pattern, and the hole pattern can be formed by combining the positive resist, and the combination with the resist is not limited. Also, as the phase shifter, a stack type,
Any of the trench types can be used. In addition, various modifications can be made without departing from the scope of the present invention.

[0039]

As described in detail above, according to the present invention, it is possible to realize an exposure mask which enables formation of a more precise device pattern for a hole pattern by the optimum phase shifter arrangement. Becomes

[Brief description of the drawings]

FIG. 1 is for explaining the first embodiment,
FIG. 6 is a diagram showing a state where a phase shifter is arranged in a storage electrode contact pattern of a 4-pitch array type DRAM cell.

FIG. 2 is a diagram showing a phase shifter arrangement in a second embodiment.

FIG. 3 is a diagram showing how a phase shifter is arranged in the third embodiment.

FIG. 4 is a diagram showing how a phase shifter is arranged in a fourth embodiment.

FIG. 5 is a diagram showing how a phase shifter is arranged in a fifth embodiment.

FIG. 6 is a diagram showing a modification of FIG.

FIG. 7 is a diagram showing how a phase shifter is arranged in the sixth embodiment.

FIG. 8 is a diagram showing how a phase shifter is arranged in the seventh embodiment.

FIG. 9 is a diagram showing a modification of FIG.

FIG. 10 is a diagram showing how the phase shifter is arranged in the eighth embodiment.

11 is a diagram showing a modification of FIG.

FIG. 12 is a diagram showing how a phase shifter is arranged in the ninth embodiment.

FIG. 13 is a diagram showing how a phase shifter is arranged in the tenth embodiment.

FIG. 14 is a diagram showing an example of a conventional phase shifter arrangement.

FIG. 15 is a diagram showing the principle of the Levenson method in comparison with the conventional method.

[Explanation of symbols]

 10 ... Transmission part pattern 11 ... Shifter arrangement part 12 ... Bit line 30, 40 ... Element area 31, 32, 33, 41, 42, 43 ... Pattern 50 ... Word line

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akiko Shinki 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Incorporated Toshiba Research and Development Center

Claims (6)

[Claims] 1. An exposure mask having an island-shaped light-transmitting portion arranged periodically and a light-shielding portion surrounding the island-shaped light-transmitting portion, and an arbitrary light-transmitting portion pattern and a light-transmitting portion pattern located around the pattern. The phase shifter layer is formed on either one of the pair of patterns such that the distance between them becomes the minimum.
Further, the exposure is characterized in that the phase shifter layer is continuously formed by a plurality of patterns so that the adjacent pattern having the smallest inter-pattern distance has the opposite phase and the adjacent pattern having the smallest inter-pattern distance has the same phase. Mask. 2. The pattern of the light transmitting portion is 1/2, 1 /
2. The exposure mask according to claim 1, which is a contact hole pattern arranged in a 3 or 1/4 pitch array system. 3. An exposure mask having an island-shaped light-transmitting portion arranged periodically and a light-shielding portion surrounding the island-shaped light-transmitting portion, wherein each light-transmitting portion pattern and a group of patterns located around the pattern are respectively arranged. An exposure mask, wherein a phase shifter layer is formed on either one of a pair of patterns that minimizes the geometrical center-of-gravity position interval. 4. An exposure mask having an island-shaped light-transmitting portion pattern arranged periodically and a light-shielding portion surrounding the island-shaped light-transmitting portion pattern, and a pattern facing an arbitrary underlying wiring layer with the wiring layer sandwiched therebetween. The exposure mask, wherein the phase shifter layers are arranged so that the light transmitted through the pair has the same phase and the light transmitted through the pattern pair located on the same side with respect to the wiring layer has the opposite phase. . 5. An exposure mask having island-shaped light transmitting portions arranged periodically and a light-shielding portion surrounding the island-shaped light transmitting portions, wherein the light transmitting portions form a hole pattern, and the same island-shaped base pattern. The phase shifter layer is arranged so that the light transmitted through the series of hole patterns connected to the same phase has the same phase, and the light transmitted through the series of hole patterns connected to the adjacent island-shaped base patterns has the opposite phase. An exposure mask characterized by having 6. An exposure mask having a plurality of island-shaped light-transmitting portions and a light-shielding portion surrounding the light-transmitting portions, wherein the light-transmitting portions form a hole pattern and are connected to the same terminal. Exposure that is characterized in that the phase shifter layers are arranged so that the light passing through the hole pattern of the same has the same phase and the light passing through the series of hole patterns that are adjacently connected to different terminals have the opposite phase. Mask.