JPH0451240A - Mask for photoetching and production thereof - Google Patents

Abstract

PURPOSE:To reduce the concentration of light on the central part of a surface on which the light is projected as well as to reduce the reflection of the light and to increase transmissivity by forming an antireflection film fit for the wavelength of light from the light source of an exposer on the surface of the transparent substrate of mask forming an original pattern. CONSTITUTION:The substrate 1 of a mask is made of quartz or low expansion glass, a Cr pattern 2 and a chromium oxide film 3 are successively formed on the substrate 1 and the entire substrate 1 is coated with an antireflection film 4 by vapor deposition with electron beams. In the case of an exposer with a light source emitting light having wavelength of G line (wavelength lambda=435 nm), a three-layered film consisting of a magnesium fluoride layer (109 nm=lambda/4), a zirconium oxide-tantalum pentoxide mixed layer (218 nm=lambda/2) and an aluminum oxide layer (109 nm=lambda/4) is formed as the antireflection film 4 on the quartz substrate 1. The distribution rate of illuminance is improved from + or -1.5% to + or -0.6% by forming the film 4 and >=99.5% transmissivity is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a photoetching mask used in an exposure apparatus for projecting an original pattern image onto a sample in the manufacturing process of semiconductor integrated circuits, and a method for manufacturing the same.

[Conventional technology]

Conventionally, an exposure device used to project an original pattern image onto a sample in the manufacturing process of semiconductor integrated circuits has a third
In FIG. 1, a configuration as shown in the figure is generally adopted, 11 is a light source, and the light emitted from the light source 11 is collected by a condensing mirror 12. Uniform 13. Plane mirror 14. The mask 16 is irradiated through a condenser lens 15 with uniform illuminance.

Next, the light that has passed through the transparent portion other than the metal light-shielding pattern (original pattern) on the mask 16 is configured to be imaged onto the sample 18 by the projection lens 17 .

And the mask 16 of the exposure apparatus configured in this way
It is constructed by forming a metal light-shielding pattern, such as a chrome pattern, on a transparent flat substrate. However, since this mask 16 has a parallel plate shape, in order to suppress reflection on the chrome pattern surface, instead of forming the light shielding pattern with a single layer chrome pattern, it was formed on the mask substrate 21 as shown in FIG. A chromium oxide film 23 is further laminated on the chromium pattern 22 to form a light-shielding pattern with two chromium layers, or a chromium oxide film 24 is first formed on the mask substrate 21 as shown in FIG. A light-shielding pattern with a three-layer chromium structure in which a chromium pattern 22 is formed on top and chromium oxide l1123 is further laminated thereon is used.

[Problem to be solved by the invention]

By the way, in the conventional two-layer or three-layer mask described above, it is possible to reduce the reflection on the metal light-shielding pattern surface, but as long as the transparent single parallel substrate 21 is used, the transparent substrate portion Reflection occurs on the upper and lower surfaces of the metal light-shielding pattern, and it is insufficient to take measures to reduce reflection only at the metal light-shielding pattern portion, and the ratio of reflection changes slightly depending on the ratio of the light-shielding portion to the transparent portion.

FIG. 6 is a diagram showing the results of measuring the illuminance distribution of the center axis of the light emitted from the light source 11 on the projection plane using an illuminance sensor when no mask is disposed in the conventional exposure apparatus. The illuminance distribution has become more uniform due to improvements in the design and manufacturing technology of devices and lenses. In FIG. 6, the horizontal axis represents the position on the projection plane, and the vertical axis represents the illuminance.

However, when measuring the illuminance distribution using the same method after setting a quartz or low expansion glass substrate to be used as a mask substrate in the same apparatus described above, it is clear that the center of the projection plane is on the mask substrate surface, as shown in Figure 7. The illuminance becomes high due to reflection. This change in illuminance at the center leads to non-uniform dimensions of the imaged pattern on the sample.
When forming a pattern using a positive resist, the dimension of the central part of the sample on the image plane becomes thinner. In other words, the illuminance distribution shown in Fig. 7 is This corresponds to dimensional accuracy.

In the submicron pattern area, 0.05μm
There are cases where dimensional accuracy is a problem, and conventional techniques cannot deal with such dimensional accuracy due to pattern dimensional changes at the center of the image plane.

Furthermore, in a mask with a two-layered light-shielding pattern shown in FIG. 4, although the reflection of the chromium pattern 22 can be reduced by using chromium oxide 23, the reflection of the chromium pattern 22 can be reduced by a few percent to several A reflection 31 of 10% is projected onto the top surface of the substrate,
Further, it is reflected by the transparent surface of the mask substrate 21 on which the chrome pattern 22 is not formed, and is transferred onto the sample 18 through the projection lens system, where it appears as a ghost image 32. Although this ghost image cannot be confirmed with normal exposure energy, it is transferred onto the sample and has an adverse effect on the pattern profile etc. on the sample.

The present invention was made in order to solve the above-mentioned problems with photoetching masks used in conventional exposure equipment, and it is possible to improve the pattern dimensions in the image formation plane of the pattern on the sample and further improve the pattern profile. An object of the present invention is to provide a photoetching mask and a method for manufacturing the same.

[Means and effects for solving the problems] In order to solve the above-mentioned problems, the present invention provides an anti-reflection film corresponding to the light source wavelength of the exposure device on at least the transparent substrate surface of a mask having an original pattern formed on the substrate. A photoetching mask is constructed by providing a photoetching mask.

With this configuration, the reflection of the irradiated light by the mask substrate is reduced and the transmittance is improved, and the concentration of light at the center of the projection plane caused by reflection is alleviated, and the pattern dimensions at the center of the projection plane are reduced. Variations are reduced and pattern dimensional accuracy on the sample can be improved. Further, by providing an antireflection film on the surface of the transparent side of the mask substrate, it is possible to eliminate ghosts of the original image pattern due to reflections from the upper surface of the mask substrate, and improve the pattern profile of the projected image.

〔Example〕

Examples will be described below. FIG. 1 is a sectional view showing an embodiment of a photoetching mask according to the present invention. Reference numeral 1 denotes a mask substrate, which is made of quartz or low-expansion glass.After forming a chromium pattern 2 and a chromium oxide film 3 on the substrate 1, the entire mask substrate 1 is deposited using an electron beam evaporation method. As the anti-reflection film 4 covered with the anti-reflection film 4, for example, G 1ine (wavelength λ-
In a device using a light source with a wavelength of 436 ns),
Magnesium fluoride film (109ns-λ/4)/mixed film of zirconium oxide and tantalum pentoxide (218n=λ/2)
)/aluminum oxide (109nm-λ/4)/substrate (
A three-layer structure made of quartz is used. When this antireflection film is provided, the illuminance distribution rate is improved from ±1.5% when no antireflection film is provided to ±0.6%. Moreover, the transmittance is also 99.5% or more.

When using this light source, in addition to the above, magnesium fluoride film (109n-) / mixed film of zirconium oxide and tantalum pentoxide (218na) / aluminum oxide film (
109nm) /Silicon oxide film (109ns) /Substrate, magnesium fluoride film/#1 zirconium oxide film/Cerium fluoride film/Substrate, magnesium fluoride film/ITO film/
An antireflection film composed of an aluminum oxide film/substrate or the like can also be used.

FIG. 2 is a diagram showing another method of forming an antireflection film.
This formation method involves liquefying the material that will become the anti-reflection film and forming the film on the entire surface of the mask substrate using a spin coating method. The antireflection film is formed on the mask substrate by dropping the antireflection material 7 and applying the antireflection material by rotating the spinner 5, or by directly applying the antireflection material while the spinner 5 is rotating.

The antireflection film can be formed either before or after the formation of a metal light-shielding pattern made of chromium, chromium oxide, etc. In addition to the electron beam method, the above vapor deposition method can also be used to form the antireflection film.
Sputtering method, CVD method, ICB method, etc. can be used.

In the above embodiment, an anti-reflection film is formed on both sides of the mask substrate, but the area where the anti-reflection film is formed does not need to be on the entire surface of the mask substrate. It is sufficient to form it only on the light-transmitting part, and when used in an exposure device equipped with a framing blade (a mechanism for reducing the irradiation area), it may be formed only on the area where the mask substrate is irradiated with the illumination light. An antireflection film may be provided on only one side.

Furthermore, the anti-reflection film is not limited to the three-layer or four-layer structure shown in the above embodiments, but may also be composed of a single-layer film or a multi-layer film with the film thickness adjusted using various materials so as to obtain the anti-reflection effect. You can also do it.

〔Effect of the invention〕

As described above based on the embodiments, according to the present invention, the reflection of irradiated light by the mask substrate is reduced, the transmittance is improved, and the concentration of light at the center of the projection plane caused by reflection is alleviated. The pattern dimensional accuracy at the center of the projection plane can be improved.

Further, by providing an anti-reflection film on the surface of the transparent side of the mask substrate, it is possible to eliminate ghosts of the original image pattern due to reflections on the upper surface of the mask substrate, and improve the pattern profile of the projected image.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one embodiment of a photoetching mask according to the present invention, FIG. 2 is an explanatory view showing another method for forming an antireflection film, and FIG. A schematic diagram showing an exposure apparatus used in the manufacturing process of integrated circuits, FIGS. 4 and 5 are cross-sectional views showing an example of the configuration of a conventional photoetching mask, and FIG. 6 is a schematic diagram showing an example of the structure of a conventional photoetching mask. Figure 7 is a diagram showing the illuminance distribution on the projection plane when a transparent substrate is set in a conventional exposure apparatus, and Figure 8 is a diagram showing the illuminance distribution on the projection plane when a conventional mask is used. , is an explanatory diagram showing how a ghost appears on a sample. In the figure, 1 is a mask substrate, 2 is a chrome pattern, 3 is a chromium oxide film, 4 is an antireflection film, 5 is a spinner, 6 is a mask substrate, and 7 is a liquefied antireflection material.

Claims (1)

[Scope of Claims] 1. In a photoetching mask used in an exposure device that exposes an original pattern in the semiconductor integrated circuit manufacturing process, at least the transparent substrate surface of the mask on which the original pattern is formed on the substrate is exposed to the wavelength of the light source of the exposure device. A photo-etching mask characterized by being provided with an anti-reflection film that is compatible with. 2. In a method for manufacturing a photoetching mask used in an exposure device that exposes an original pattern in a semiconductor integrated circuit manufacturing process, an antireflection film corresponding to the wavelength of the light source of the exposure device is formed on the substrate by vapor deposition or coating, and then A method for manufacturing a photoetching mask, which comprises forming an original pattern on an antireflection film. 3. In a method for manufacturing a photoetching mask used in an exposure device that exposes an original pattern in a semiconductor integrated circuit manufacturing process, after forming an original pattern on a substrate,
A method for manufacturing a photoetching mask, comprising forming an antireflection film corresponding to the wavelength of a light source of an exposure device on the substrate by vapor deposition or coating over the original pattern.