JP2589137B2 - Exposure method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to an exposure method in a semiconductor device manufacturing process or the like, and more particularly, to a method for improving contrast when exposing a pattern surface of a reticle or a mask toward a light source side. Alternatively, an exposure method that can improve the contrast by reducing the influence of diffracted light or the like and perform high-precision and stable pattern exposure, as well as using a single mask for normal rotation and reversal patterns to obtain efficient use of the mask. For the purpose of providing, a mask in which a pattern film (12) is formed on the front side of the glass substrate (11) and a polarizing film (13) is formed on the back side, and the polarizing film (13) side is exposed to light ( The exposure method is arranged so as to face the 15) side and irradiates light from the pattern film (12) side.

[Industrial applications]

The present invention relates to an exposure method in a semiconductor device manufacturing process or the like, and more particularly, to a method for improving contrast when exposing a reticle or a mask with a pattern surface facing a light source.

[Conventional technology]

Conventionally, in a semiconductor device manufacturing process, a mask (or reticle) on which a circuit pattern or the like is formed has been used to form a fine pattern on a wafer by a projection exposure method. Since it is necessary to perform high-precision exposure for this mask with miniaturization of elements, the shift amount is considered by combining light intensity and resist sensitivity in consideration of the effects of scattered or diffracted light. The pattern is controlled by making it thicker or thinner.

FIG. 4 is a view showing a conventional exposure method. As shown in the figure, the mask has a metal pattern 2 made of a material such as chromium formed on a glass substrate 1, and the surface on which the metal pattern 2 is formed (pattern surface) is to be exposed. Light is incident on the resist film 4 formed on the wafer 3 from a side other than the pattern surface, and the resist film 4 is formed.
Is exposed. In this way, by irradiating light with light incident from the side other than the pattern surface, it is possible to prevent a decrease in contrast due to light reflected on the inner surface by the metal pattern 2 or the like inside the glass substrate 1.

[Problems to be solved by the invention]

However, in the conventional exposure method, as the elements are further miniaturized, it becomes difficult to control the exposure pattern with high precision and stability due to the influence of scattered light or diffracted light. In addition, a mirror-inverted pattern may be required for a predetermined pattern. However, when light is incident from a side other than the pattern surface to obtain the inverted pattern, as described above, the metal pattern 2 or the like inside the glass substrate 1 is used. There is a problem that the contrast is lowered due to the internal reflected light due to the above. Therefore, conventionally, a dedicated mask (or reticle) has been formed and exposed for the reverse pattern exposure.

Therefore, the present invention can improve the contrast by reducing the influence of scattered light or diffracted light, perform high-precision and stable pattern exposure, and use only one mask for the normal rotation and the reverse pattern, thus improving the efficiency of the mask. An object of the present invention is to provide an exposure method that can be used.

[Means for solving the problem]

The object is to form a pattern film on the front surface side of a glass substrate and dispose a mask having a polarizing film formed on the back surface, with the polarizing film side facing the exposure target side, and irradiating light from the pattern film side. The above problem is solved by an exposure method characterized in that:

[Action]

That is, in the present invention, since the mask having the polarizing film formed on the back surface side is arranged and exposed so that the polarizing film side faces the exposure target side, the reflected light inside the glass substrate, when entering the glass substrate, Light such as refracted light is blocked by the polarizing film. Therefore, the contrast can be improved by reducing the influence of the scattered light or the diffracted light. Further, light can be incident from the polarizing film side by inverting the above mask, and the normal rotation and inversion patterns can be completed by one mask, so that the mask can be efficiently used.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to an embodiment shown in the drawings.

FIG. 1 is a view showing an exposure method according to a first embodiment of the present invention, and FIG.
The figure is a perspective view of the mask of FIG. As shown in these figures, a mask has a metal pattern film 12 made of a material such as chromium on the upper surface side of a glass substrate 11 made of a material such as quartz.
(In the figure, an L-shaped pattern is formed). Such a metal pattern film 12 is formed by forming a metal thin film on the upper surface of the glass substrate 11 by, for example, vacuum evaporation or sputtering, and patterning the metal thin film by etching. On the back side of the glass substrate 11, a polarizing film 13 is formed.
The polarizing film 13 includes H film, K film, and J film which are often used.
Film, L film, HR film, etc., but it is common to use ultraviolet light as an exposure light source for LSI especially in semiconductor manufacturing.
A film having little so-called "blue leakage", whose performance is degraded with respect to ultraviolet light often seen in a polarizer, is used. It is preferable to use HN-22 type having high polarization performance for the H film and KN-36 having high resistance for the K film. Such a polarization film is made by absorbing iodine into polyvinyl alcohol. To perform pattern exposure using the mask thus formed, the side on which the polarizing film 13 is formed is opposed to the resist film 15 formed on the wafer 14 to be exposed, and the metal pattern film is formed. With the side on which 12 is formed facing the light source 16, the ultraviolet light emitted from the light source 16 is transmitted through a mask and strikes the resist film 15.

According to the above-described exposure method, the metal pattern film 12
The ultraviolet light (light shown by the A line in FIG. 1) perpendicularly incident on the glass substrate 11 on which the
Through the polarizing film 13 to expose the resist film 15. Also,
Even if the light enters the glass substrate 11, the ultraviolet light scattered on the surface of the polarizing film 13 (the light indicated by the B line in FIG. 1) is reflected on the surface of the glass substrate 11 and returns, Does not transmit through the polarizing film 13. Further, even when the ultraviolet light incident on the glass substrate 11 is refracted by the glass substrate 11 (the light indicated by the C line in FIG. 1), the ultraviolet light does not pass through the polarizing film 13 due to the polarization shift. That is, reflected and scattered light inside the glass substrate 11, or refracted light when incident on the glass substrate 11,
Since only the ultraviolet light that is perpendicularly incident on the glass substrate 11 is transmitted through the polarizing film 13 without being blocked by the polarizing film 13 and transmitted, the pattern exposure of the metal pattern film 12 is performed. Therefore, the influence of scattered light or diffracted light can be reduced to improve the contrast, and highly accurate and stable pattern exposure can be performed.

Further, using the mask, the side on which the metal pattern film 12 is formed is opposed to the resist film 15 formed on the wafer 14 to be exposed, and the side on which the polarizing film 13 is formed is a light source. By passing ultraviolet light emitted from the light source 16 through the mask toward the resist film 15 toward the 16 side, exposure of an inverted pattern (an inverted L-shaped pattern in the embodiment) becomes possible. Also in this case, since only the ultraviolet light transmitted through the polarizing film 13 passes through the glass substrate 11 and exposes the resist film 15, similarly, the influence of the scattered light or the diffracted light can be reduced to improve the contrast. Therefore, the normal rotation and the reverse pattern can be completed with one mask, and the mask can be efficiently used.

FIG. 3 is a view for explaining an exposure method according to a second embodiment of the present invention. Parts corresponding to the first embodiment are denoted by the same reference numerals. In the figure, the same mask as that of the first embodiment is arranged such that the side on which the polarizing film 13 is formed faces the resist film 15 to be exposed. On the side where the metal pattern film 12 is formed, a polarizer 17 is arranged between the mask and the light source 16. That is, the ultraviolet light from the light source 16 is polarized by the polarizer 17 and is incident on the mask.

According to the above-described exposure method, the ultraviolet light emitted from the light source 16 is incident on the mask as the specific polarized light by the polarizer 17, and the polarization shift of the reflected scattered light inside the glass substrate 11 and the refracted light when incident is performed. Light can be removed by the polarizer 17. Therefore, similarly to the first embodiment, the effect of scattered light or diffracted light can be reduced to improve the contrast, achieve high-precision and stable pattern exposure, and use only one mask for normal and reverse patterns. The mask can be used efficiently.

In the present invention, a mask in which the polarizing film 13 is formed on the back side of the glass substrate 11 may be used.
It is desirable that 13 has high polarization performance with respect to ultraviolet light, which is an exposure light source for LSI manufacture, and has high durability without any change in properties.

Further, by irradiating the mask with light polarized by the polarizer 17 as in the second embodiment, the influence of scattered light or diffracted light can be further reduced.

Further, the metal pattern film 12 is formed on at least a glass substrate.
It suffices if it is formed on the surface side of 11, and the present invention is also applied to those using materials other than chromium.

In the present invention, the mask also includes a reticle.

〔The invention's effect〕

As described above, according to the present invention, since a mask having a polarizing film formed on the back surface is exposed by disposing the polarizing film side so as to face the exposure target side, the reflected light inside the glass substrate, the glass substrate Light such as refracted light upon incidence is blocked by the polarizing film, so that the influence of scattered light or diffracted light can be reduced and the contrast can be improved. Further, light can be incident from the polarizing film side by inverting the above mask, and the normal rotation and inversion patterns can be completed by one mask, so that the mask can be efficiently used.

[Brief description of the drawings]

 FIG. 1 is a view showing an exposure method of the first embodiment of the present invention, FIG. 2 is a perspective view of the mask of FIG. 1, FIG. 3 is a view showing an exposure method of the second embodiment of the present invention, FIG. FIG. 3 is a view showing a conventional exposure method. In the figure, 11 is a glass substrate, 12 is a metal pattern film, 13 is a polarizing film, 14 is a wafer, 15 is a resist film, 16 is a light source, and 17 is a polarizer.

Claims (1)

(57) [Claims] 1. A mask having a pattern film (12) formed on the front surface side of a glass substrate (11) and a polarizing film (13) formed on the back surface side. An exposure method comprising irradiating light from the side of the pattern film (12).