JPH0784356A - Phase shift mask and manufacturing method thereof - Google Patents

Abstract

(57) [Summary] [Object] An exposure mask having a phase shift structure and a method for manufacturing the same are intended to efficiently expose a plurality of types of fine patterns. [Structure] In a method of manufacturing a phase shift mask in which a step is formed on a transparent substrate 11 at an opening portion of a light shielding film 12 to form a main pattern and a phase shifter, first, two kinds of openings 1AA and 2AA are formed in the light shielding film 12. , Transparent substrate with openings 1AA, 2AA
The thickness of 11 is reduced by etching and main patterns 1A, 2A
Then, a predetermined width around the opening 1AA of the light shielding film 12 is removed by etching to form a phase shifter 1B having a first width,
Further, a predetermined width around the opening 2AA of the light shielding film 12 is removed by etching to form a phase shifter 2B having a second width, and a phase shift mask in which two types of phase shifters having different widths are mixed is manufactured. Two types of fine patterns can be exposed at the same time.

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 a method for manufacturing the same. 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 rays by giving a phase difference to the exposure rays that pass through the photomask.
Has been attracting attention, and an exposure method using a mask having a phase shift structure (hereinafter referred to as a phase shift mask) is being put into practical use.

[0002]

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

Among them, the edge enhancement method is such that a phase shifter having a constant width is provided along an edge of an opening of a light-shielding film, and light passing through the phase shifter and a main pattern surrounded by the phase shifter are transmitted. It provides a phase difference with the light to be generated, and has a relatively wide range of application, and the mask manufacturing is easy because the phase shifter pattern can be formed by self-alignment with the main pattern.

In order to manufacture the phase shift mask of this method, first, an opening corresponding to the main pattern is formed in the light shielding film on the transparent substrate, then the thickness of the transparent substrate in this opening is reduced by etching, and thereafter, The light-shielding film is removed by etching within a certain width around the opening. A portion where the transparent substrate is thinned by etching becomes a main pattern, and a portion where the light shielding film is later removed (the thickness of the transparent substrate remains the same) becomes a phase shifter.

By the way, the optimum value of the width of the phase shifter changes depending on the dimensions of the pattern to be exposed. When the phase shifter is formed by self-alignment with the main pattern as described above, the width of this phase shifter is determined by the processing conditions of the step of enlarging the opening of the light shielding film. It is difficult to make them in the same mask in the manufacturing process.

Therefore, conventionally, when exposing a device pattern formed by combining patterns of various shapes and sizes, the exposure mask is composed of a plurality of divided masks divided by the width dimension of the phase shifter. They were manufactured in the same manufacturing process.

[0007]

However, when the exposure mask is composed of a plurality of divided masks in this manner, the same photoresist film must be sequentially exposed by using the divided masks sequentially. There was a problem that it became complicated and required a long time.

An object of the present invention is to solve such problems and provide a phase shift mask capable of efficiently exposing a plurality of types of fine patterns and a method of manufacturing the same.

[0009]

According to the present invention, the object of the present invention is to provide: [1] an opening for a first pattern exposure and a second pattern exposure for a light-shielding film deposited on the surface of a transparent substrate. An opening for a plurality of types of pattern exposure including an opening, and in the opening for the first pattern exposure, the transparent substrate is a first phase shifter having a first width and a first phase shifter. The transparent substrate is surrounded by a first main pattern having a thickness smaller than that of the first phase shifter, and the transparent substrate has a second phase shifter having a second width and an opening for exposing the second pattern. A phase shift mask comprising a second main pattern surrounded by a second phase shifter and having a thickness smaller than that of the second phase shifter. [2] The method for manufacturing a phase shift mask according to the above [1], wherein the light shielding film has a plurality of types of patterns including an opening for the first pattern exposure and an opening for a second type pattern exposure. A step of forming exposure openings in the same size as each main pattern including a first main pattern and a second main pattern, which are formed in subsequent steps, respectively, and the transparent in self-alignment with each of the plurality of types of openings. Forming a plurality of types of main pattern recesses including the first main pattern and the second main pattern on the substrate; forming a photoresist film over the entire surface of the transparent substrate; Selectively exposing only the first pattern exposure opening from the back surface side of the transparent substrate, and then developing the same, and surrounding the first pattern exposure opening of the light shielding film with the first pattern exposure opening. One A step of forming the first phase shifter by expanding the opening by removing the photoresist film on the entire front surface side of the transparent substrate, and removing the photoresist film from the back surface of the transparent substrate. After selectively exposing only the second pattern exposure opening from the side, a step of developing this, and the periphery of the second pattern exposure opening of the light shielding film in the range of the second width. And a step of forming the second phase shifter by expanding the opening to remove the second phase shift mask.

[0010]

In the present invention, only in the step of determining the width of the phase shifter, the manufacturing method in which only the regions of the phase shifter having the same width are selectively processed sequentially, a plurality of types of phase shifters having different widths are self-aligned. It became possible to make one mask in the process. As a result, it becomes possible to expose a plurality of types of fine patterns having different shapes and dimensions at one time with a single phase shift mask and obtain a desired resolution for all of the plurality of types of patterns.

[0011]

EXAMPLE An example of the phase shift mask according to the present invention will be described with reference to FIG. FIG. 1 is a schematic view showing an embodiment of the phase shift mask of the present invention. This example is an edge enhancement type phase shift mask for exposing two kinds of hole patterns having different sizes (that is, the first pattern 1 and the second pattern 2 in FIG. 1A). Note that this mask is for reduction projection exposure, and is enlarged five times as large as the pattern to be actually transferred to the photoresist film.

In this phase shift mask, an opening for exposing the first pattern 1 and a second pattern 2 are formed on a light shielding film 12 made of chromium or the like deposited on the surface of a transparent substrate 11 made of quartz glass or the like. An opening is provided for exposing. In these openings, the transparent substrate 11 is thin, leaving its peripheral edge with a constant width. The thinned portions (recesses) are the main patterns 1A and 2A, and the peripheral portions are the phase shifters 1B and 2B. The widths of the phase shifters 1B are all the same and the widths of the phase shifters 2B are also the same, but the widths of 1B and 2B are different.

The thickness difference (step) between the phase shifter 1B and the main pattern 1A and between the phase shifter 2B and the main pattern 2A is equal, and both are 180 degrees between the light ray passing through the phase shifter and the light ray passing through the main pattern. It is a value that causes a phase difference of °.

Next, a method of manufacturing this phase shift mask will be described with reference to FIGS. FIG. 2 is a schematic view showing a method for manufacturing a phase shift mask of the present invention, and FIG. 3 is a view showing a mask used for manufacturing the phase shift mask of the present invention.

First, a light-shielding film 12 made of chromium or the like is deposited on the surface of a transparent substrate 11 made of quartz glass or the like.
After forming an opening 1AA having the same size as the main pattern 1A and an opening 2AA having the same size as the main pattern 2A in 12 by an electron beam exposure method or the like, a photoresist 13 is applied to the front surface side of the transparent substrate 11 and the back surface side UV light is radiated from the photoresist to selectively expose the photoresist 13 using the light shielding film 12 as a mask (FIG. 2 (a)).
reference). Next, the photoresist 13 is developed, and the transparent substrate 11 is dry-etched using the photoresist 13 as a mask to form main patterns 1A and 2A having recesses of a desired depth on the transparent substrate 11 (see FIG. 2 ( b)).

Next, after peeling off the photoresist 13, a new photoresist 14 is applied on the surface side of the transparent substrate 11,
Next, ultraviolet rays are radiated from the back surface side of the transparent substrate 11 through a first mask 15 (see FIG. 3 (A)) that shields the area other than the area where the main pattern 1A is arranged to selectively expose the photoresist 14. Exposure (see Fig. 2 (c)). Next, the photoresist 14 is developed (see FIG. 2 (d)). After that, the photoresist 14 is ashed with oxygen plasma to shield the light around the main pattern 1A (phase shifter 1B formation region).
Expose 12 (see Figure 2 (e)). Next, this light shielding film 12
The exposed portion of is removed by the dry etching method.

Next, after peeling off the photoresist 14, a new photoresist 16 is applied on the surface side of the transparent substrate 11,
Next, ultraviolet rays are radiated from the back surface side of the transparent substrate 11 through a second mask 17 (see FIG. 3B) that shields the area other than the area where the main pattern 2A is arranged, so that the photoresist 16 is selectively selected. Exposure (see Fig. 2 (f)). Next, the photoresist 16 is developed (see FIG. 2 (g)). Then, the photoresist 16 is ashed by oxygen plasma to shield the light around the main pattern 2A (phase shifter 2B forming region).
Expose 12 (see Figure 2 (h)). Next, this light shielding film 12
The exposed portion of is removed by the dry etching method.

After that, when the photoresist 16 is peeled off,
Shifter patterns 1B, which have different widths from the main patterns 1A, 2A,
An edge-enhanced phase shift mask composed of 2B and the light shielding film 12 is completed (see FIG. 2 (i)).

Using the phase shift mask prepared by the above method, two kinds of fine hole patterns are simultaneously exposed on the same photoresist film, and then developed.
The resolution of the obtained resist pattern was all good.

The present invention is not limited to the above embodiments, but can be implemented with various modifications. For example, the present invention is effective even when three or more types of phase shifters having different widths are formed in the same mask. Further, by applying the present invention, it is possible to mix different phase shift structures in the same mask or mix regions having no phase shift structure.

[0021]

As described above, according to the present invention,
A phase shift mask capable of exposing a plurality of types of fine patterns at one time and a manufacturing method thereof can be provided, which contributes to high integration and high density of semiconductor devices.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a phase shift mask of the present invention.

FIG. 2 is a diagram showing an embodiment of a phase shift mask manufacturing method of the present invention.

FIG. 3 is a diagram showing a mask used for manufacturing the phase shift mask of the present invention.

[Explanation of symbols]

 1 1st pattern 1A Main pattern (1st main pattern) 1AA, 2AA Opening 1B Phase shifter (1st phase shifter) 2 2nd pattern 2A Main pattern (2nd main pattern) 2B Phase shifter (2nd) Phase shifter) 11 Transparent substrate 12 Light-shielding film 13, 14, 16 Photoresist (photoresist film) 15 First mask 17 Second mask

Claims (2)

[Claims] 1. A light-shielding film deposited on the surface of a transparent substrate (11).
(12) has a plurality of types of pattern exposure openings including a first pattern exposure (1) opening and a second pattern (2) exposure opening, and the first pattern (1) In the opening for exposure, the transparent substrate (11) is surrounded by a first phase shifter (1B) having a first width and the first phase shifter (1B) and the first phase shifter (1B).
B) consists of a first main pattern (1A) which is thinner than the second pattern (2), and the transparent substrate (11) has a second phase shifter having a second width in the opening for exposure. (2B) and the second phase shifter (2B) and is surrounded by the second phase shifter (2B).
B) A phase shift mask comprising a second main pattern (2A) which is thinner than B). 2. The method of manufacturing a phase shift mask according to claim 1, wherein the light-shielding film (12) has an opening (1AA) for exposing the first pattern (1) and a second pattern (2). ) A plurality of types of patterns including the opening for exposure (2AA) Each main pattern including the first main pattern (1A) and the second main pattern (2A) for forming respective openings for exposure in a subsequent step And the transparent substrate (1) by self-aligning with the plurality of types of openings.
1) a step of forming a plurality of types of main pattern recesses including the first main pattern (1A) and the second main pattern (2A), and photolithography on the entire surface side of the transparent substrate (11). After forming a resist film (14) and selectively exposing the photoresist film (14) from the back surface side of the transparent substrate (11) to the first pattern (1) exposure opening (1AA) region only , A step of developing this, and the opening (1A) for exposing the first pattern (1) of the light shielding film (12)
A) The opening is removed by removing the periphery in the range of the first width (1AA)
The step of forming the first phase shifter (1B) by enlarging, and forming a photoresist film (16) on the entire surface side of the transparent substrate (11), and forming the photoresist film (16) A step of selectively exposing only the second pattern (2) exposure opening (2AA) region from the back surface side of the transparent substrate (11), and then developing the second pattern (2) of the light shielding film (12). Pattern (2) Opening for exposure (2A
A) The opening is removed by removing the periphery in the range of the second width (2AA)
And a step of forming the second phase shifter (2B) by enlarging.