JPH07261367A - Photomask and its production - Google Patents

Abstract

PURPOSE:To improve the corrosion resistance to a high energy light and to enhance the resolution by coating the surface of translucent film and phase shift film with a light shielding film and setting the area of the apertures of the light shielding film larger than the area of the apertures of the translucent film and phase shift film. CONSTITUTION:The surface of a transparent substrate 1 is provided successively with the translucent films 5 for exposing light of photoresist films, the phase shift films 2 for shifting the phases of this light and the light shielding films 3 of exposing light. The area of the apertures 4 of the light shielding films 3 is set larger than the area of the apertures 4 of the translucent films 5 and the phase shift films 2. Namely, the surfaces of the two-layered structural films composed of the translucent films 5 and the phase shift films 2 are coated with the light shielding films 3 consisting of chromium. The apertures 4 of the larger area than the area of the apertures 4 of the translucent films 5 and the phase shift films 2 are formed at the light shielding films 3 consisting of the chromium on the apertures 4. Since the translucent films 5 are surely shielded to light, the multiple exposing of the photoresist films does not arise any more and the resolution of the irradiation light transmitted therethrough is enhanced by the apertures 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photomask, and more particularly to improvement of a photomask using a phase shift film which can obtain a high resolution photoresist film pattern.

As shown in FIG. 7 (a), this photomask mask has a transparent substrate 1 made of quartz or the like which constitutes a photomask, and a light-transmissive material that converts the phase of light for exposure and transmits the light. For example, the phase shift film 2 made of a thin film of SiO ₂ film is partially arranged in the opening 4 in which the light shielding film 3 made of chromium is opened.

As shown in FIG. 7 (b), the light A that has passed through the phase shift film 2 and has its phase converted and the light B that has not passed through the phase shift film 2 and whose phase has not been converted. Take advantage of interference.

Then, as shown in FIG. 7 (c), the skirts of the light intensities of the two lights A and B having different phases interfere with each other and cancel each other out, so that high-resolution exposure is possible. It will be possible.

[0005]

2. Description of the Related Art Conventionally, as a structure of a photomask film using such a phase shift film, as shown in FIG. 8 (a), a semitransparent film 5 in which chromium is thinly formed on a transparent substrate 1 made of quartz. Is opened in a predetermined pattern to provide an opening 4, and the transparent substrate 1 immediately below the opening 4 is selectively etched,
There is a structure in which the transparent substrate 1 is phase-shifted.

As another structure, as shown in FIG. 8 (b), there is a structure in which the semi-transmissive film 5 and the phase shift film 2 are provided in a two-layer structure and the openings 4 having a predetermined pattern are provided. A halftone mask using these phase shift films 2 is
In both cases, the light amount of the irradiation light transmitted through the semi-transmissive film 5 is reduced, and the phase of the irradiation light is inverted between the opening 4 and the phase shift portion below the semi-transmissive film 5, and the transmitted irradiation light is transmitted. The resolution of the mask exposure is increased by improving the resolution of the above in the opening 4.

[0007]

[Problems to be Solved by the Invention] However, FIG. 8 (a) and FIG. 8 (b)
As shown in FIG. 3, in the halftone mask using the phase shift film 2 of the conventional structure described above, the semi-transmissive film 5 transmits 10% of the light amount, and the stepper of the exposure apparatus is used to form a photoresist film for pattern formation. During exposure, the stepper stage repeats the step and repeat operation.

Therefore, the exposure light causes multiple exposure of the photoresist film through the semi-transmissive film 5, and this multiple exposure causes a problem such as a defect in the pattern. Furthermore, when light of short wavelength and high energy such as an excimer laser is used as a light source for exposure, there is a problem that the phase shift film 2 is damaged due to damage caused by irradiation.

An object of the present invention is to solve the above-mentioned problems and form a photomask using a mask forming material which is not damaged by high energy light. In addition, the entire surface of the transparent substrate is irradiated with light from the back side of the transparent substrate at once by using the opening to prevent multiple exposure by the stepper,
It is an object of the present invention to provide a photomask in which no pattern defect occurs and a manufacturing method thereof.

[0010]

The photomask of the present invention comprises:
An exposure light semi-transmissive film of a photoresist film, a phase shift film for shifting the phase of the light, and a light-shielding film for the exposure light are sequentially provided on the transparent substrate as claimed in claim 1, and an opening of the light-shielding film is formed. The area of the part is larger than the area of the openings of the semi-transmissive film and the phase shift film.

Further, as described in claim 2, a semi-transparent film made of silicon carbide or silicon carbonitride also serving as a phase shift film, and a light shielding film are sequentially provided on a transparent substrate, and an opening portion of the light shielding film is formed. Is larger than the area of the opening of the semi-transmissive film that also serves as the phase shift film.

Further, when the wavelength of the exposure light of the photoresist film is λ and N is an integer, the silicon carbide film is defined by the refractive index and absorption coefficient of silicon carbide or silicon carbonitride. , Or the optical thickness of the silicon carbonitride film is (2
It is characterized in that N + 1) λ / 2.

According to a fourth aspect of the present invention, a silicon carbide film or a silicon carbonitride film having a predetermined pattern is provided on the transparent substrate in a single layer structure. According to a fifth aspect of the present invention, there is provided a method of manufacturing a photomask, comprising the steps of sequentially forming a semitransparent film of a photoresist film, a semitransparent film of exposure light, a phase shift film, and a light-shielding film on a transparent substrate. No. 1 photoresist film is formed, the first photoresist film is exposed and developed to form a predetermined pattern, and then the light-shielding film, the phase shift film, and the semitransparent film are formed by using the patterned first photoresist film as a mask. A step of sequentially etching the film, a step of removing the first photoresist film, and a step of applying a second photoresist film on the entire surface of the transparent substrate, irradiating light from the back side of the transparent substrate, and the semi-transmission Of exposing the second photoresist film in an area larger than the area of the openings of the photosensitive film and the phase shift film to form the exposed portion, and developing and removing the exposed portion, the patterned second photoresist The film as a mask, after etching the lower portion of the light shielding film, removing the second photoresist film on the light shielding film, the semi-permeable membrane,
It is characterized in that a photomask having a light shielding film having an opening area larger than the opening area of the phase shift film is formed.

According to a sixth aspect of the present invention, a step of sequentially forming a semi-transmissive film and a light-shielding film, which also functions as a phase shift film made of a silicon carbide film or a silicon carbonitride film, on a transparent substrate, on the substrate. Forming a first photoresist film on the photoresist, exposing and developing the photoresist film to form a predetermined pattern,
A step of sequentially etching a semi-transmissive film that also serves as a light-shielding film and a phase shift film using the patterned first photoresist film as a mask, after removing the first photoresist film, the entire surface of the transparent substrate is removed. A step of applying a second photoresist film, irradiating light from the back side of the transparent substrate, and having an area larger than the area of the opening on the opening of the light-shielding film on the semi-transmissive film that also serves as the phase shift film. And exposing the second photoresist film to form an exposed portion, and removing the exposed portion by development, after etching the light shielding film using the patterned second photoresist film as a mask, The second photoresist film is removed, and a light shielding film having an opening having an area larger than the area of the opening of the semitransparent film also serving as the phase shift film is formed.

[0015]

In the photomask of the present invention, the two-layer structure film of the semi-transmissive film and the phase shift film is covered with the light shielding film made of chromium, and the opening is formed on the openings of the semi-transmissive film and the phase shift film. An opening having a larger area than the portion is formed in the light shielding film made of a chromium film.

By doing so, the semi-transmissive film is surely shielded from light, so that the photoresist film is not exposed to multiple exposures. As shown in FIG. 1 (a), each of the halftone masks using these phase shift films 2 reduces the amount of irradiation light transmitted by the semi-transmissive film 5, and reduces the amount of irradiation light with the opening 4 and the semi-transmissive film. As shown in FIG. 1 (b), the phase shift of the irradiation light is performed between the film 5 and the phase shift part under the film.

Then, as shown in FIG. 1 (c), the resolution of the mask exposure is increased by improving the resolution of the transmitted irradiation light at the opening 4. Further, as shown in FIG. 6, the film thickness is 4387Å
The silicon carbide film has a spectral transmittance of 10% for the light from the exposure light source with a wavelength of λ = 365 nm, and is a semi-transmissive film that also serves as a phase shift film. Less damage.

Thus, by using the silicon carbide film as the semi-transmissive film that also serves as the phase shift film, deterioration of the phase shift film due to damage of high-energy light such as X-rays can be reduced, and light can be shielded on top of this. Even if the films are laminated, the structure is a two-layer film, so that the film structure is simple and a halftone photomask provided with a phase shift film that is not deteriorated by exposure light can be obtained.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.
The details will be described. As shown in FIG. 1 (a), the first embodiment of the photomask of the present invention has a transparent substrate 1 made of quartz having an opening 4 of a predetermined size, and a thin chromium (Cr) layer of 100 to 300 Å. ) Forming a semi-permeable membrane 5 consisting of a film,
Phase shift films 2 and 50 consisting of an O ₂ film with a thickness of 3500 to 4000Å
A light shielding film 3 made of a Cr film having a thickness of 0Å to 1000Å is formed.

The dimension A of the opening between the light shielding films 3
Is kept larger than the dimension B of the opening of the semi-transmissive film 5 and the phase shift film 2, so that the area of the opening between the light-shielding films 3 becomes larger than the opening between the semi-transmissive film 5 and the phase shift film 2. Larger than the area of the part.

To form such a photomask of the first embodiment, as shown in FIG. 2A, a transparent substrate 1 such as quartz is used.
A semi-transparent film 5 made of a chromium (Cr) film, which is thinly formed at 100 to 300 Å, is formed on top of this, and a phase shift film 2 made of a SiO ₂ film having a thickness of 3500 to 4000 Å and 500 Å ~ A light shielding film 3 made of a Cr film having a thickness of 1000Å is formed.

Then, as shown in FIG. 2 (b), a first photoresist film having openings 4 of a predetermined pattern on the substrate 1 is formed.
11 is formed by the steps of coating, exposing, and developing the photoresist film.

Then, using the patterned first photoresist film 11 as a mask, the light-shielding film 3 is sequentially etched with the phase shift film 2 and the semi-transmissive film 5 to form a mask pattern.

Then, after removing the first photoresist film 11 by ashing, a second photoresist film 12 is applied to the entire surface of the substrate 1 as shown in FIG. More ultraviolet rays are irradiated, and the irradiation direction of the ultraviolet rays is changed by an optical device so that the exposed portion 13 is formed on the light-shielding film 3 so as to be larger than the opening 4 formed in the above process.

Next, the exposed portion 13 of the second photoresist film 12 described above is removed with a developer, and the light-shielding film 3 is etched using the second photoresist film 12 as a mask, as shown in FIG. 2 (d).

Then, the second photoresist film 12 is removed to form a photomask having the structure shown in FIG. 2 (e). A second embodiment of the photomask of the present invention is shown in FIG. As shown in the figure, the photomask of the second embodiment is a semi-transmissive silicon carbide film which also serves as a phase shift film for the semi-transmissive film and the phase shift film of the first embodiment, or a single layer of the silicon carbonitride film 14. It is a point that the structural film is used instead.

Then, a light-shielding film 3 having a size B larger than the size A of the openings between the silicon carbide films or the silicon carbonitride films 14 which are semi-transmissive films also serving as the phase shift film is formed.

When the refractive index of this silicon carbide film is 3.16 and the absorption coefficient is 0.259, the optical film thickness of the silicon carbide film is (2N +
1) The thickness should be λ / 2. In this embodiment, when the wavelength of ultraviolet rays used for exposure is 248 nm, the optical film thickness is 580Å.

Further, the refractive index of the silicon carbonitride film is 2.45, the absorption coefficient is 0.27, and the optical film thickness of the silicon carbonitride film is (2N
+1) A thickness of λ / 2 is formed by using the CVD method, the vapor deposition method, or the sputtering method. In this embodiment, when the wavelength of ultraviolet rays used for exposure is 248 nm, the optical film thickness is 870Å.

Then, a light-shielding film 3 made of chromium is formed on this.
Form a film with a thickness of 500 to 1000Å. By keeping the dimension A of the opening between the light shielding films 3 larger than the dimension B of the opening of the silicon carbide film or the silicon carbonitride film, the area of the opening between the light shielding films 3 is reduced. Alternatively, it is made larger than the area of the opening between the silicon carbonitride films.

A method of manufacturing such a photomask of the second embodiment will be described. As shown in FIG. 4 (a), a semi-transmissive silicon carbide film also serving as a phase shift film or a silicon nitride film 14 having a thickness of the above-mentioned optical film is formed on a transparent substrate 1 such as quartz. The film is formed by the CVD method, the sputtering method, or the vapor deposition method.

Next, as shown in FIG. 4B, a first photoresist film having openings 4 of a predetermined pattern is formed on the substrate 1.
11 is formed by the steps of coating, exposing, and developing the photoresist film.

Then, using the patterned first photoresist film 11 as a mask, the light-shielding film 3, a semi-transmissive silicon carbide film also serving as a phase shift film, or a silicon carbonitride film 14 is formed.
Are sequentially etched to form a mask pattern.

Next, after removing the first photoresist film 11 by ashing, a second photoresist film 12 is applied to the entire surface of the substrate 1 as shown in FIG. More ultraviolet rays are irradiated, and the irradiation direction of the ultraviolet rays is changed by an optical device so that the exposed portion 13 is formed on the light-shielding film 3 so as to be larger than the opening 4 formed in the above process.

Next, the exposed portion 13 of the second photoresist film 12 described above is removed with a developer, and the light-shielding film 3 is etched using the second photoresist film 12 as a mask, as shown in FIG. 4D.

Then, the second photoresist film 12 is removed to form a photomask having the structure shown in FIG. 4 (e). A third embodiment of the present invention is shown in FIG. 5 (c). As shown in the figure, a silicon carbide film or a silicon carbonitride film 14 formed in a predetermined pattern is formed on the transparent substrate 1 made of quartz in a predetermined pattern. As described above, the thickness of the silicon carbide film or the silicon carbonitride film is an optical value defined by the refractive index value and the absorption coefficient of the silicon carbide film and the silicon carbonitride film, where the wavelength of the light from the exposure light source is λ. Is formed by a CVD method, a sputtering method, an evaporation method, or the like so that the film thickness becomes a value of (2N + 1) λ / 2.

As shown in FIG. 5 (a), this manufacturing method uses a silicon carbide film or a silicon carbonitride film 14 having the above-mentioned optical film thickness on the transparent substrate 1 by the above-mentioned CVD method or sputtering method. Form a film.

Next, as shown in FIG. 5B, a photoresist film 15 is applied on the substrate 1 and then exposed and developed to form a photoresist film 15 having a predetermined pattern. Then figure
As shown in FIG. 5 (c), a silicon carbide film having a predetermined pattern or a photomask having a silicon carbonitride film 14 can be formed by etching using the patterned photoresist film 15 as a mask.

[0039]

As described above, according to the photomask of the present invention, since the surfaces of the semi-transmissive film and the phase shift film are covered with the light shielding film, multiple exposure is performed using the stepper of the exposure apparatus. However, the damage of the mask disappears.

Further, a silicon carbide film or a silicon carbonitride film, which has corrosion resistance against short-wavelength and high-energy light such as X-rays, can transmit a predetermined amount of exposure light according to wavelength, and can shift the phase. By using it instead of a film in which a phase shift film and a semi-transmissive film are laminated, the film structure is simplified, manufacturing is easy, and high-energy light has corrosion resistance, and a high-resolution photomask is obtained. is there.

[Brief description of drawings]

FIG. 1 is a structure and characteristic diagram of a photomask according to a first embodiment.

FIG. 2 is a cross-sectional view showing a manufacturing process of the photomask of the first embodiment.

FIG. 3 is a structure and characteristic diagram of a photomask of a second embodiment.

FIG. 4 is a cross-sectional view showing the manufacturing process of the photomask of the second embodiment.

FIG. 5 is a sectional view showing a photomask and a manufacturing process of a third embodiment.

FIG. 6 is a relationship diagram of the transmittance of the silicon carbide film with respect to the wavelength.

FIG. 7 is an explanatory diagram of the principle of a photomask using a phase shift film.

FIG. 8 is a sectional view of a conventional photomask.

[Explanation of symbols]

 1 transparent substrate 2 phase shift film 3 light shielding film 4 opening 5 semi-transmissive film 11 first photoresist film 12 second photoresist film 13 exposed portion 14 silicon carbide film (silicon carbonitride film) 15 photoresist film

Claims (6)

[Claims] 1. A semitransparent film (5) for exposing light of a photoresist film on a transparent substrate (1), a phase shift film (2) for shifting the phase of the light, and a light shielding film (3) for the exposing light. ) Are sequentially provided, and the area of the opening (4) of the light-shielding film (3) is changed to a semi-permeable film.
(5) A photomask characterized by having a larger area than the opening (4) of the phase shift film (2). 2. A semi-transmissive film (14) made of silicon carbide or silicon carbonitride also serving as a phase shift film on a transparent substrate (1).
And the light-shielding film (3) are sequentially provided, and the area of the opening of the light-shielding film (3) is made larger than the area of the opening of the semi-transmissive film (14) which also serves as the phase shift film. And a photo mask. 3. When the wavelength of the exposure light of the photoresist film is λ and N is an integer, the silicon carbide film or the silicon carbonitride film is defined by the refractive index and absorption coefficient of silicon carbide or silicon carbonitride. The photomask according to claim 2, wherein the optical film thickness is (2N + 1) λ / 2. 4. A photomask characterized in that a silicon carbide film or a silicon carbonitride film (14) having a predetermined pattern is provided on a transparent substrate (1) in a single layer structure. 5. A semitransparent film (5) for exposing light of a photoresist film, a phase shift film (2) and a light-shielding film (3) on a transparent substrate (1).
Forming a first photoresist film (11) on the substrate (1), exposing and developing the first photoresist film (11) to form a predetermined pattern, and then forming the pattern. Light-shielding film (3) and phase shift film (2) using the formed first photoresist film (11) as a mask
And a step of sequentially etching the semi-transparent film (5), a step of removing the first photoresist film (11) and then applying a second photoresist film (12) on the entire surface of the transparent substrate (1). The second photoresist film (12) is irradiated with light from the back side of the transparent substrate (1) and is larger than the area of the semi-transparent film (5) and the opening (4) of the phase shift film (2). ) To expose the exposed part (13)
And removing the exposed portion (13) by developing, the lower light-shielding film (3) is etched by using the patterned second photomask film (12) as a mask, and then the light-shielding film (3) is removed.
(3) The second photoresist film (12) above is removed, and an opening (4) having a larger area than the area of the opening (4) of the semitransparent film (5) and the phase shift film (2) is formed. A method of manufacturing a photomask, comprising forming a light-shielding film (3) provided. 6. A semi-transmissive film (1) made of a silicon carbide film or a silicon carbonitride film also serving as a phase shift film on a transparent substrate (1).
4) and a step of sequentially stacking the light shielding film (3), forming a first photoresist film (11) on the substrate (1), exposing and developing the photoresist film (11) to a predetermined pattern Then, the patterned first photoresist film (1
Step of sequentially etching the light-shielding film (3) and the semi-transmissive film (14) also serving as a phase shift film by using 1) as a mask, after removing the first photoresist film (11), the transparent substrate (1) A step of applying a second photoresist film (12) on the entire upper surface, irradiating light from the back side of the transparent substrate (1), and a light-shielding film on the semi-transmissive film (14) also serving as the phase shift film (3) opening
(4) A step of exposing the second photoresist film (12) with an area larger than the area of the opening (4) to form an exposed portion (13), and removing the exposed portion by development, the pattern After etching the light shielding film (3) using the formed second photoresist film (12) as a mask, the second photoresist film (12) on the light shielding film (3) is removed to serve also as the phase shift film. A method of manufacturing a photomask, comprising forming a light-shielding film (3) having an opening (4) having an area larger than that of the opening (4) of the semi-transparent film (14).