TW201636736A - Mask assembly and photolithography process using the same - Google Patents

Abstract

A mask assembly including a first mask and a second mask is provided. The first mask includes a plurality of paralleled first main features, a plurality of first sub-resolution assistant features (SRAFs) and a plurality of second SRAFs. The second SRAFs are separately disposed at a side of the first main features. The first SRAFs are separately disposed between the second SRAFs and the first main features. The extending direction of the first main features is parallel with that of the second SRAFs. The second mask includes a plurality of paralleled second main features. When the first mask and the second mask are individually disposed above a negative-type photoresist layer, the second main features intersect with the first main features and the second main features overlap with the first SRAFs.

Description

Photomask set and lithography process using the same

The present invention relates to a reticle, and more particularly to a reticle set for Double Exposure (DE).

The photolithography process is a critical process in the entire semiconductor process, and how to further narrow the critical dimension will be a constant challenge for all R&D personnel. Among the challenges of pattern shrinkage, a variety of prior art techniques have been proposed, such as double exposure (DE), double lithography (Litho-Etch Litho-Etch, LELE), and far ultraviolet lithography (Extreme). Ultraviolet Lithography (EUVL), Self-Alignment Double Patterning (SADP), Negative-Tone Development (NTD), Directed Self-Assembly (DSA). Since the power source power required for the current ultra-ultraviolet lithography (EUVL) has not yet been upgraded to a mass production state, and the materials required for directed self-assembly (DSA) are still in the research and development stage, the current semiconductor manufacturing process mostly relies on Multi Pattering technology to reduce critical dimensions. For example, dual exposure (DE) with negative tone development (NTD) process technology can effectively reduce the size of the Contact Hole.

The Challenge of the lithography process In addition to the miniaturization of the graphics, the increase in the Process Window is another key factor in whether the process can be introduced into mass production. In general, a good reticle pattern design is absolutely helpful for improving the process margin. In the above process, in the process technology of double exposure (DE) with negative tone development (NTD), how to improve the process margin through proper mask pattern design is one of the problems that researchers are trying to solve.

The present invention provides a photomask assembly that enhances the process margin of the lithography process.

The present invention provides a lithography process that has a good process margin.

The photomask assembly of the present invention is used for double exposure of a negative-type developing photoresist layer. The photomask group includes a first photomask and a second photomask. The first reticle includes a plurality of first main patterns arranged in parallel with each other, a plurality of first sub-resolution assistant features (SRAF), and a plurality of second sub-resolution auxiliary patterns, and the second resolving auxiliary patterns are mutually Separatingly disposed on one side of the first main pattern, the first parsing auxiliary patterns are disposed apart from each other between the first main pattern and the second parsing auxiliary pattern, and the extending direction of the first main pattern is parallel to the second parsing auxiliary The direction in which the pattern extends. The second photomask includes a plurality of second main patterns arranged in parallel with each other, and the first photomask and the second photomask are disposed above the negative development photoresist layer When the predetermined position is to be separately exposed, the second main pattern is interlaced with the first main pattern, and the second main pattern overlaps with the first analysis auxiliary pattern.

The lithography process of the present invention includes the following steps. First, the aforementioned photomask set is provided. Next, the negative development resist layer is subjected to secondary exposure with the first mask and the second mask as masks, respectively. Thereafter, the negative development photoresist layer is developed.

In an embodiment of the invention, when the first reticle and the second reticle are placed at the predetermined positions to perform exposure, respectively, the extending direction of the first main pattern is perpendicular to the extending direction of the second main pattern.

In an embodiment of the invention, when the first reticle and the second reticle are placed at the predetermined positions to perform exposure, respectively, the extending direction of the first analytic auxiliary pattern is parallel to the extending direction of the second main pattern.

In an embodiment of the invention, the arrangement pitch of the first analysis auxiliary patterns is the same as the arrangement pitch of the second main patterns.

In an embodiment of the invention, when the first reticle and the second reticle are placed at predetermined positions to respectively perform exposure, the second analytic auxiliary pattern does not overlap with the first main pattern and the second main pattern.

In an embodiment of the present invention, the second mask may further include a plurality of third-time analysis auxiliary patterns and a plurality of fourth-time analysis auxiliary patterns, and the fourth analysis auxiliary patterns are separated from each other and disposed on the second main pattern. On one side, the third analysis auxiliary patterns are disposed apart from each other between the second main pattern and the fourth resolving auxiliary pattern, and the extending direction of the second main pattern is parallel to the extending direction of the fourth resolving auxiliary pattern.

In an embodiment of the invention, when the first reticle and the second reticle are placed at predetermined positions to respectively perform exposure, the extending direction of the third analytic auxiliary pattern is parallel to the extending direction of the first main pattern.

In an embodiment of the invention, the arrangement pitch of the third resolution auxiliary pattern is the same as the arrangement pitch of the first main pattern.

In an embodiment of the invention, when the first reticle and the second reticle are placed at predetermined positions to respectively perform exposure, each of the third analytic auxiliary patterns is respectively disposed between the adjacent two first main patterns, and The third resolution auxiliary pattern does not overlap with the first main pattern.

In an embodiment of the invention, when the first reticle and the second reticle are placed at predetermined positions to respectively perform exposure, the fourth analytic auxiliary pattern does not overlap with the first main pattern and the second main pattern.

Based on the above, since the present invention employs the design of the first analysis auxiliary pattern and the second analysis auxiliary pattern, the present invention can improve the process margin of the lithography process.

The above described features and advantages of the invention will be apparent from the following description.

M1, M1’‧‧‧ first mask

M2, M2'‧‧‧ second mask

PR‧‧‧Negative developed photoresist layer

P‧‧‧Predetermined location

110‧‧‧ first main pattern

120‧‧‧First analysis of auxiliary patterns

130‧‧‧Second analytical auxiliary pattern

210‧‧‧second main pattern

220‧‧‧The third analytical auxiliary pattern

230‧‧‧ Fourth analysis of auxiliary patterns

1 is a schematic view of a lithography process in accordance with a first embodiment of the present invention.

2A and 2B are respectively the first photomask and the second photomask in the first embodiment. view.

FIG. 3 is a schematic view showing the relative relationship between the two masks when the first mask and the second mask of the first embodiment are placed at predetermined positions above the negative development resist layer to respectively perform exposure.

4A and 4B are schematic views of a patterned photoresist layer formed by exposure development of a negative development photoresist layer via different mask designs.

FIG. 5 is a schematic view showing the relative relationship between the two masks when the first mask and the second mask of the second embodiment are placed at predetermined positions above the negative development resist layer to respectively perform exposure.

6A and FIG. 6B are schematic diagrams of a patterned photoresist layer formed by exposure development of a negative development photoresist layer via different mask designs.

[First Embodiment]

1 is a schematic view of a lithography process in accordance with a first embodiment of the present invention. Referring to FIG. 1, the lithography process of this embodiment includes the following steps. First, a mask group including a first mask M1 and a second mask M2 is provided. Next, the negative development photoresist layer PR is subjected to secondary exposure with the first mask M1 and the second mask M2 as masks, respectively. Here, in this embodiment, the first photomask M1 is used as the mask to expose the negative development photoresist layer PR for the first time, and then the second mask M2 is used as the mask to the negative development photoresist layer PR. Performing a second exposure; or, first, using the second mask M2 as a mask to expose the negative development photoresist layer PR for the first time, and then using the first mask M1 The second exposure of the negative development photoresist layer PR is performed for the mask. In other words, the present embodiment does not limit the order of use of the first reticle M1 and the second reticle M2. In the present embodiment, the negative development resist layer PR is formed, for example, on the wafer W or other substrate. Typically, the negative development photoresist layer PR will overlie the conductive or dielectric film to be patterned. After the completion of the repeated exposure, the negative development resist layer PR is developed. For example, the aforementioned development is, for example, negative tone development.

In order to ensure that the reticle used in the lithography process has a good exposure resolution at the edge thereof, thereby improving the process margin of the lithography process, the embodiment is applied to the first reticle M1 and the second reticle M2. Specially designed sub-resolution assistant feature (SRAF). The first mask M1 and the second mask M2 will be described in detail below with reference to FIGS. 2A, 2B, and 3 to 4.

2A and 2B are respectively a top view of the first photomask and the second photomask in the first embodiment, and FIG. 3 is a view of placing the first photomask and the second photomask of the first embodiment on the negative development photoresist. A schematic diagram of the relative relationship of the two masks when the predetermined position above the layer is separately exposed.

Referring to FIG. 2A and FIG. 2B , the first mask M1 of the present embodiment includes a plurality of first main patterns 110 , a plurality of first-time analytical auxiliary patterns 120 , and a plurality of second-time analytical auxiliary patterns 130 arranged in parallel with each other. As shown in FIG. 2A and FIG. 2B, the second analysis auxiliary patterns 130 are disposed apart from each other on at least one side of the first main pattern 110, and the first analysis auxiliary patterns 120 are disposed apart from each other in the first main patterns 110 and the second. The secondary analysis auxiliary patterns 130 are interposed, and the extending direction of the first main patterns 110 is parallel to the extending direction of the second analysis auxiliary patterns 140. For example, The primary analytical auxiliary pattern 120 and the second analytical auxiliary pattern 130 are generally distributed around the periphery of the first primary pattern 110 to enhance the exposure resolution of the first mask M1 at its edges. Further, the second photomask M2 includes at least a plurality of second main patterns 210 arranged in parallel with each other.

Referring to FIG. 1 to FIG. 3, when the first mask M1 and the second mask M2 are placed at a predetermined position P (shown in FIG. 1) above the negative development resist layer PR for exposure, respectively, The two main patterns 210 are interlaced with the first main pattern 110, and the second main pattern 210 may overlap with the first resolving auxiliary pattern 120. As shown in FIG. 3, the overlapping area of the first analysis auxiliary pattern 120 and the second main pattern 210 is the area of the first analysis auxiliary pattern 120 itself. Further, the arrangement pitch of the first analysis auxiliary patterns 130 is the same as the arrangement pitch of the second main patterns 210.

As shown in FIG. 3, when the first mask M1 and the second mask M2 are placed at the aforementioned predetermined position P to perform exposure twice respectively, the extending direction of the first main pattern 110 is, for example, perpendicular to the second main. The direction in which the pattern 210 extends. The extending direction of the first analysis auxiliary pattern 120 is, for example, parallel to the extending direction of the second main pattern 210. Further, the second analysis auxiliary pattern 130 does not overlap with the first main pattern 110 and the second main pattern 210.

In addition to the second main pattern 210, the second mask M2 may further include a plurality of third-time analysis auxiliary patterns 220 and a plurality of fourth-time analysis auxiliary patterns 230, and the fourth analysis auxiliary patterns 230 are disposed apart from each other in the second One side of the main pattern 210, the third analysis auxiliary pattern 220 is disposed apart from each other between the second main pattern 210 and the fourth resolving auxiliary pattern 230, and the extension of the second main pattern 210 The direction is parallel to the extending direction of the fourth analysis auxiliary pattern 230. For example, the third resolution auxiliary pattern 220 and the fourth analysis auxiliary pattern 230 are generally distributed on the periphery of the second main pattern 210 to enhance the exposure resolution of the second mask M2 at the edges thereof.

As shown in FIG. 3, when the first mask M1 and the second mask M2 are placed at the predetermined position P described above to perform exposure twice, respectively, the extending direction of the third analysis auxiliary pattern 220 is parallel to the first main. The direction in which the pattern 110 extends is the same as the arrangement pitch of the first primary pattern 110. Each of the third analysis auxiliary patterns 220 is disposed between the adjacent two first main patterns 110, and the third analysis auxiliary pattern 220 does not overlap with the first main patterns 110. Further, the fourth analysis auxiliary pattern 230 does not overlap with the first main pattern 110 and the second main pattern 210.

In the foregoing first embodiment, simultaneously using the first resolution auxiliary pattern 120 and the second resolution auxiliary pattern 130 can significantly improve the exposure resolution of the first mask M1 and the second mask M2 at the edges thereof. The details will be described below in conjunction with FIG. 4.

4A and 4B are schematic views of a patterned photoresist layer formed by exposure development of a negative development photoresist layer via different mask designs. Referring to FIG. 4A and FIG. 4B , in the first embodiment, the first reticle has a first main pattern, a first analytic auxiliary pattern, and a second analytic auxiliary pattern, and the second reticle has a second main pattern, The third resolution auxiliary pattern and the fourth analysis auxiliary pattern; in Comparative Example 1, the first mask has only the first main pattern and the second analysis auxiliary pattern, and The second reticle has only the second main pattern and the fourth analytic auxiliary pattern; in the second embodiment, the first reticle has only the first main pattern and the first resolving auxiliary pattern, and the second reticle has only the first Two main patterns and a third auxiliary pattern.

4A and 4B, in Comparative Example 1 and Comparative Example 2, the resolution of the patterned photoresist layer at the edge corresponding to the edge of the mask (the left edge in the drawing) was poor. In contrast, in the first embodiment, the exposure analysis at the edge of the mask (the left edge in the figure) is performed due to the design of the first analysis auxiliary pattern, the second analysis auxiliary pattern, the third analysis auxiliary pattern, and the fourth analysis auxiliary pattern. Significant improvements can be achieved.

As can be clearly seen from FIG. 4A and FIG. 4B, the lithography process using the first reticle and the second reticle of the present embodiment has the best focus position or 60 nm deviation from the optimal focus position. Very good process margin.

[Second embodiment]

FIG. 5 is a schematic view showing the relative relationship between the two masks when the first mask and the second mask of the second embodiment are placed at predetermined positions above the negative development resist layer to respectively perform exposure. Referring to FIG. 5, the first mask M1' and the second mask M2' of the present embodiment are similar to the first mask M1 and the second mask M2 (shown in FIG. 3) of the first embodiment. The main difference is that the overlapping positions of the first main pattern 110 and the second main pattern 210 in this embodiment are different, and only the second main pattern 210 is present on the second mask M2 ′.

6A and FIG. 6B are schematic diagrams of a patterned photoresist layer formed by exposure development of a negative development photoresist layer via different mask designs. Please refer to Figure 6A with 6B, in the second embodiment, the first reticle has a first main pattern, a first analytic auxiliary pattern, and a second analytic auxiliary pattern, and the second reticle has only the second main pattern; in Comparative Example 1 The first reticle has only the first main pattern and the second analytic auxiliary pattern, and the second reticle has only the second main pattern; in the comparative example 2, the first reticle has only the first main pattern and the first The auxiliary pattern is resolved once, while the second mask has only the second main pattern.

6A and 6B, in Comparative Example 3 and Comparative Example 4, the resolution of the patterned photoresist layer at the edge corresponding to the mask was poor. In contrast to the second embodiment, the exposure resolution at the edge of the reticle can be significantly improved due to the first analysis of the auxiliary pattern and the design of the second analysis auxiliary pattern.

As can be clearly seen from FIG. 6A and FIG. 6B, the lithography process using the first reticle and the second reticle of the present embodiment has the best focus position or 60 nm deviation from the optimal focus position. Very good process margin.

It should be noted that the present invention does not limit the design patterns of the first and second main patterns on the first reticle and the second reticle. The general knowledge in the field can change the first and second main patterns according to actual design requirements. .

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and any one of ordinary skill in the art can make some changes and refinements without departing from the spirit and scope of the present invention. The scope of the invention is defined by the scope of the appended claims.

M1‧‧‧ first mask

M2‧‧‧second mask

110‧‧‧ first main pattern

120‧‧‧First analysis of auxiliary patterns

130‧‧‧Second analytical auxiliary pattern

220‧‧‧The third analytical auxiliary pattern

Claims (10)

A photomask set for double exposure of a negative-type developing photoresist layer, the photomask group comprising: a first photomask comprising a plurality of first main patterns arranged in parallel with each other, and a plurality of first-time resolution aids a pattern and a plurality of second analysis auxiliary patterns, wherein the second analysis auxiliary patterns are disposed apart from each other on one side of the first main pattern, and the first analysis auxiliary patterns are separated from each other and disposed on the first main pattern and Between the second analysis auxiliary patterns, and the extending directions of the first main patterns are parallel to the extending directions of the second resolving auxiliary patterns; and a second photo mask comprising a plurality of parallel lines arranged in parallel with each other a second main pattern, when the first mask and the second mask are placed at a predetermined position above the negative developing photoresist layer to respectively perform exposure, the second main patterns are interlaced with the first main patterns, And the second main patterns overlap with the first parsing auxiliary patterns. The reticle set of claim 1, wherein when the first reticle and the second reticle are placed at the predetermined position for respectively exposing, the extending directions of the first main patterns are perpendicular to the The direction in which the second main pattern extends. The reticle group of claim 1, wherein when the first reticle and the second reticle are placed at the predetermined position to respectively perform exposure, the first analytic auxiliary patterns extend in a direction parallel to The direction in which the second main patterns extend. The reticle set of claim 1, wherein the arrangement intervals of the first analytic auxiliary patterns are the same as the arrangement pitch of the second main patterns. The photomask set according to claim 1, wherein the first photomask and the photomask When the second mask is placed at the predetermined position to perform exposure respectively, the second resolution auxiliary patterns do not overlap with the first main patterns and the second main patterns. The reticle set of claim 1, wherein the second reticle further comprises a plurality of third analytic auxiliary patterns and a plurality of fourth analytic auxiliary patterns, the fourth analytic auxiliary patterns are separated from each other And disposed on a side of the second main pattern, the third sub-analytical auxiliary patterns are disposed apart from each other between the second main pattern and the fourth sub-analytical auxiliary patterns, and extending directions of the second main patterns Parallel to the extension directions of the fourth analysis auxiliary patterns. The reticle group of claim 6, wherein when the first reticle and the second reticle are placed at the predetermined position for exposure, respectively, the third analytic auxiliary patterns extend in a direction parallel to The direction in which the first main patterns extend. The reticle set of claim 6, wherein the arrangement intervals of the third analytic auxiliary patterns are the same as the arrangement pitch of the first main patterns. The reticle group of claim 6, wherein when the first reticle and the second reticle are placed at the predetermined position to respectively perform exposure, each of the third analytic auxiliary patterns are respectively disposed adjacent to each other. Between the two first main patterns, and the third analysis auxiliary patterns do not overlap with the first main patterns. The reticle group of claim 6, wherein the fourth reticle auxiliary pattern does not overlap with the first reticle and the second reticle when the predetermined position is placed for exposure. A primary pattern and the second primary patterns overlap.