JPH0777796A - Mask for exposure and exposure method - Google Patents

Abstract

PURPOSE:To provide the mask for exposure and exposure method capable of transferring all of plural kinds of fine patterns with good resolution relating to the mask for exposure having a phase shift structure and the exposure method using this mask for exposure. CONSTITUTION:The mask for exposure is composed of a first division mask 10 having the edge emphasis type phase shift structure for exposing hole patterns 1 and a second division mask 20 having a Levenson type phase shift structure for exposing line/spacing patterns 2 at the time of transferring the patterns consisting of the fine hole patterns 1 and the fine line/spacing patterns 2. The same photoresist film is successively exposed by successively using the first division mask 10 and the second division mask 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure mask having a phase shift structure and an exposure method using the exposure mask.

In recent years, semiconductor devices have been continuously miniaturized in response to the demand for high integration and high density.
As a technology that breaks through the limit of pattern miniaturization in the ultraviolet exposure method, the "phase shift method" that improves the resolution by using the interference between the exposure light rays by giving a phase difference to the exposure light rays that pass through the photomask is attracting attention. The exposure method using a mask (hereinafter, referred to as a phase shift mask) having a structure that causes a phase difference (hereinafter, referred to as a phase shift structure) is being put into practical use.

[0003]

2. Description of the Related Art As a phase shift method, various methods such as an edge enhancement method and a Levenson method having different mask phase shift structures have been proposed (see, for example, Nikkei Microdevice magazine, May 1991, pages 52 to 58). ).

Among these, the edge enhancement type phase shift mask is provided with a phase shifter having a constant width along the periphery of the opening of the light shielding film, the opening pattern is composed of a shifter pattern and a main pattern, and the shifter pattern is transmitted. A phase difference is provided between the incident light and the light transmitted through the main pattern. The Levenson type phase shift mask gives a phase difference to the light transmitted through both by changing the thickness of one transparent substrate of the adjacent transparent patterns to that of the other transparent substrate.

Conventionally, any one type of phase shift mask has been used for exposing one photoresist film.

[0006]

None of these various phase shift methods improve the resolution to the same extent for all patterns. For example, when the edge enhancement type phase shift mask is used, the effect of improving the resolution is great for the hole pattern, but it is slight for the line / space pattern, while the Levenson type phase shift mask is used. In this case, it is difficult to apply it to the hole pattern, but the effect of improving the resolution is great for the line / spacing pattern. Further, in the case of the edge enhancement type phase shift mask, the optimum width of the shifter pattern varies depending on the pattern size.

However, since an actual device pattern is formed by combining patterns of various shapes and sizes, when it is necessary to improve the resolution of a plurality of types of patterns, one phase shift method is used. There is a problem that it is difficult to obtain a desired resolution for all of a plurality of types of patterns by adopting it.

The present invention solves such a problem and uses an optimum phase shift mask according to the shape and size of a pattern to expose all fine patterns with good resolution and an exposure mask. It is an object to provide an exposure method.

[0009]

According to the present invention, the object is [1] a mask for exposing a plurality of types of patterns including a first pattern and a second pattern, which is provided on a light-shielding film. The first split mask for the first pattern exposure having a first phase shift structure provided with a phase shifter along the periphery of the exposure opening, and the first phase shift structure is at least a phase shifter. [2] by using a plurality of divided masks including a second divided mask for exposing the second pattern having a second phase shift structure having different arrangements of [2]. A mask for exposing a plurality of types of patterns including a first pattern and a second pattern, the mask having a first width along the periphery of the first pattern exposure opening of the first light-shielding film. First with phase shifter And a plurality of split masks including a split mask and a second split mask provided with a phase shifter having a second width along the periphery of the second pattern exposure opening of the second light-shielding film. By using a characteristic exposure mask, [3] the same photoresist film is formed by sequentially using a plurality of division masks including the first division mask and the second division mask in [1] or [2] above. This is achieved by using an exposure method characterized by sequential exposure.

[0010]

When a plurality of types of device patterns formed by combining patterns of various shapes and sizes need to be improved in resolution, a plurality of phase shift methods suitable for the respective patterns (that is, If the dimensions of the phase shift structure) or the phase shifter are adopted, a desired resolution can be obtained for all of the plurality of types of patterns. However, it is not always possible to make masks having different phase shift structures in the same manufacturing process, and it is not always possible to make masks having phase shifters of different sizes under the same processing conditions.

The present invention has a mask having an edge-enhanced phase shift structure capable of forming a phase shifter by a self-alignment process, and another phase shift structure, instead of forming them in one mask. I divided it into a mask,
Further, in the edge-emphasized phase shift structure, since the mask is divided for each width of the phase shifter, there is no difficulty in the manufacturing process thereof, and therefore a mask with few defects can be easily obtained. Since these masks have an optimum phase shift structure according to the shape and size of the pattern, it becomes possible to transfer a fine pattern with high resolution.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of an exposure mask and an exposure method according to the present invention will be described with reference to FIGS. 1, 3 and 4.

FIG. 1 is a plan view and a sectional view showing the mask structure of the first embodiment. This example is intended to improve the resolution of the hole pattern 1 and the line / spacing pattern 2 (see FIG. 1 (A)). The edge pattern is used for the exposure of the hole pattern 1, and the line / spacing pattern 2 is also used. The Levenson method is used for each of the exposures, and the exposure mask is the first split mask 10 for exposure of the hole pattern 1 (see FIGS. 1 (B1) and (B1).
2)) and a second division mask 20 (see FIGS. 1 (C1) and (C2)) for line / spacing pattern 2 exposure.

First division mask 10 and second division mask 20
In both cases, light-shielding films 12 and 22 made of chromium or the like are adhered to the surfaces of transparent substrates 11 and 21 made of quartz glass or the like.
22 has an opening, but the opening differs between the two.

The first division mask 10 has a hole pattern 1
In the opening provided in the light-shielding film 12 for exposing the transparent substrate 11, the thickness of the transparent substrate 11 is thin while leaving the peripheral portion thereof with a constant width. This thinned portion (recess) is the main pattern
1A, the shifter shifter pattern 1B at the peripheral portion, and the thickness difference (step) is a value that causes a phase difference of 180 ° between the light rays that pass through the two.

The second division mask 20 has openings formed in the light-shielding film 22 for exposing the line / spacing pattern 2, that is, one of two adjacent line patterns 2A and 2B of a plurality of line patterns arranged in parallel is more than the other. The transparent substrate 21 is thin. This difference in thickness is a value that causes a 180 ° phase difference between the rays that pass through them.

The first division mask 10 (that is, the edge enhancement type phase shift mask) and the second division mask 20 (that is, the Levenson type phase shift mask) are manufactured as follows.

FIG. 3 is a sectional view showing an example of a method of manufacturing an edge-enhanced phase shift mask. First, the light-shielding film 12 made of chromium or the like is formed on the surface of the transparent substrate 11 made of quartz glass or the like.
Then, an opening having the same size as the main pattern is formed in the light shielding film 12 by an electron beam exposure method or the like (see FIG. 3 (a)). Next, a photoresist 13 is applied to the front surface side of the transparent substrate 11, and ultraviolet rays are irradiated from the back surface side to selectively expose the photoresist 13 (see FIG. 3B). Next, the photoresist 13 is developed (see FIG. 3C). Then this photoresist 13
The transparent substrate 11 is etched by using the mask as a mask.
A main pattern 1A is formed on the surface (see FIG. 3D).

Next, after the photoresist 13 is once peeled off, another photoresist 14 is applied to the front surface side of the transparent substrate 11 again, and ultraviolet rays are irradiated from the back surface side to expose the photoresist 15.
Is selectively exposed (see FIG. 3 (e)). Next, the photoresist 14 is developed (see FIG. 3 (f)). After that, the light-shielding film 1
Side-etch 2 to widen the opening (see Figure 3 (g)). Next, when the photoresist 14 is peeled off, the edge enhancement type phase shift mask 10 including the shifter pattern 1B, the main pattern 1A and the light shielding film 12 is completed (see FIG. 3 (h)).

FIG. 4 is a sectional view showing an example of a method for manufacturing a Levenson-type phase shift mask. First, a light-shielding film 22 made of chromium or the like is formed on the surface of a transparent substrate 21 made of quartz glass or the like.
And a large number of linear openings to be a light transmitting pattern are provided in the light shielding film 22 by an electron beam exposure method or the like (see FIG. 4 (a)). Next, a photoresist 23 is applied to the front surface side of the transparent substrate 21,
The photoresist 23 is selectively exposed by irradiating ultraviolet rays from the back surface side through a mask 24 that shields one of the adjacent openings (that is, shields every other opening) (see FIG. 4B). Next, the photoresist 23 is developed (see FIG. 4 (c)). After that, using this photoresist 23 as a mask, the transparent substrate 21
Is etched to form a linear transparent pattern 2B (see FIG. 4).
(See (d)). After that, when the photoresist 23 is removed,
The Levenson-type phase shift mask 20 in which the transparent substrates 21 have different thicknesses in the adjacent linear light-transmitting patterns 2A and 2B is completed (see FIG. 4 (e)).

Next, an exposure method using these masks will be described. A reduction projection exposure apparatus is used as the exposure apparatus. Therefore, the first division mask 10 and the second division mask
In all of the above 20, the above-mentioned patterns are all magnified five times as much as the desired resist pattern. The first split mask 10 first exposes the hole pattern 1 and then the second split mask 20 exposes the line / spacing pattern 2. At this time, the same alignment marks on the exposed side (that is, the wafer) side are used for the mask alignment with the first division mask 10 and the second division mask 20.

The fine hole pattern and the fine line / spacing pattern were exposed on the same photoresist film by the above method, and then developed. As a result, the resolution of the obtained resist pattern was good.

Next, a second embodiment of the exposure mask and the exposure method according to the present invention will be described with reference to FIG. FIG. 2 is a plan view and a cross-sectional view showing the mask structure of the second embodiment. In this example, the resolution is improved for two types of hole patterns 3 and 4 having different sizes (see FIG. 2 (A)), both of which employ the edge enhancement method.
The width of the phase shifter is different. Therefore, the exposure mask is the first split mask 30 (FIG.
1) and (B2)) and a second divided mask 40 for exposing the hole pattern 4 (see FIGS. 2C1 and 2C2).

First division mask 30 and second division mask 40
In both cases, light-shielding films 32 and 42 made of chromium or the like are deposited on the surfaces of transparent substrates 31 and 41 made of quartz glass or the like.
An opening is provided in 42, and the transparent substrates 31 and 41 are thin in thickness, leaving the peripheral portion of the opening a constant width. This thin part is the main pattern 3A, 4A,
The peripheral portions are shifter shifter patterns 3B and 4B, and the widths of the shifter shifter patterns 3B and 4B are different. The thickness difference (that is, the step) of the transparent substrates 31 and 41 between the main patterns 3A and 4A and the shifter shifter patterns 3B and 4B is equal to each other, and there is a value that causes a phase difference of 180 ° between the light rays that are transmitted together. There is.

Since both the first division mask 30 and the second division mask 40 are edge enhancement type phase shift masks, their manufacturing method is the same as that of the division mask 10 described in the first embodiment. Omitted because there is. However, in the step of side-etching the light-shielding film (see FIG. 3G), the processing conditions are different between the first divided mask 30 and the second divided mask 40.

Next, an exposure method using these masks will be described. This is the same as that described in the first embodiment, and the reduction projection exposure apparatus is used to first expose the hole pattern 3 by the first division mask 30 and then by the second division mask 40. The hole pattern 4 is exposed. At this time, the same alignment marks on the side of the object to be exposed (that is, the wafer) are used for both the mask alignment with the first division mask 30 and the alignment alignment mark with the second division mask 40.

As a result of exposing two kinds of fine hole patterns on the same photoresist film by the above method and then developing, the resolutions of the obtained resist patterns were all good.

The present invention is not limited to the above embodiments, but can be carried out in various modified forms. For example, the present invention is effective even when the exposure mask is composed of three or more divided masks and these are sequentially used to sequentially expose the same photoresist film.

[0029]

As described above, according to the present invention,
It is possible to provide an exposure mask and an exposure method capable of transferring a plurality of types of fine patterns all with good resolution, which contributes to high integration and high density of semiconductor devices.

[Brief description of drawings]

FIG. 1 is a diagram showing a mask configuration of a first embodiment of the present invention.

FIG. 2 is a diagram showing a mask configuration of a second embodiment of the present invention.

FIG. 3 is a diagram showing a method of manufacturing an edge-emphasized phase shift mask.

FIG. 4 is a diagram showing a method for manufacturing a Levenson-type phase shift mask.

[Explanation of symbols]

 1,3,4 Hall pattern 1A, 3A, 4A Main pattern 1B, 3B, 4B Shifter pattern 2 lines / spacing pattern 2A, 2B Linear translucent pattern 10, 30 First division mask 11, 21, 31, 41 Transparent Substrate 12, 22, 32, 42 Light-shielding film 13, 14, 23 Photoresist 20, 40 Second split mask 24 Mask

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location 7352-4M H01L 21/30 528

Claims (3)

[Claims] 1. A first pattern (1) and a second pattern
A mask for exposing a plurality of types of patterns including (2), the first phase shift structure comprising a phase shifter (1B) along the periphery of the exposure opening provided in the light shielding film (12). The first pattern (1) having the first split mask (10) for exposure, and the second phase shift structure having a second phase shift structure different from the first phase shift structure at least in the arrangement of phase shifters. (2) An exposure mask comprising a plurality of division masks including a second division mask (20) for exposure. 2. The first pattern (3) and the second pattern
A mask for exposing a plurality of types of patterns including (4), having a first width along the periphery of the first pattern (3) exposure opening of the first light-shielding film (32) A first division mask (30) provided with a phase shifter (3B) and a phase having a second width along the periphery of the second pattern (4) exposure opening of the second light shielding film (42) An exposure mask comprising a plurality of divided masks including a second divided mask (40) having a shifter (4B). 3. The first division mask according to claim 1 or 2.
An exposure method, wherein the same photoresist film is sequentially exposed using a plurality of divided masks including (10, 30) and the second divided masks (20, 40) in order.