JPH0320733A - Photomask - Google Patents

Abstract

PURPOSE:To shorten exposure time by increasing exposing light quantity by making a glass part of a contacting hole pattern part into a lens shape. CONSTITUTION:This photomask is constituted of a convex lens 5 formed in the contacting hole part on a glass surface of a glass substrate 1, a concave lens 6 is formed in the contacting hole part on the pattern surface, and a light shielding film 2 formed on other pattern surfaces. Thus, plane wave light from light source 3 which irradiates the convex lens 5 part is deflected, made into a concave shaped wave surface condensing toward the concave lens 6, to irradiate over a water as plane wave exposing light 4.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a photomask for forming a contact hole pattern in a semiconductor substrate with a small amount of exposure.

Conventional technology In recent years, the development of semiconductor devices, especially MOS transistors, has progressed, and their importance has become even more important.
In order to meet this demand, considerably high production capacity is required. Currently, when forming a MOS transistor and electrically connecting two different conductive layers, a contact hole P is formed. A conventional contact hole type photomask will be explained below.

FIG. 2 shows a conventional contact hole type photomask. In Figure 2, 1 is a Galanu substrate;
2. It is a light shielding film. 3 is a light source light, and 4 is an exposure light.

The operation of the photomask constructed as described above will be explained below.

! First, when the light source light 3 is applied to the glass substrate 1, only the portion where the light shielding film 2 is not deposited is vertically transmitted as exposure light 4.

Problems to be Solved by the Invention However, in the conventional structure described above, exposure is performed using a flat photomask, and the light source light passes through the glass substrate perpendicularly and becomes exposure light. Due to the influence of light diffraction from the edges of the light-shielding pattern, the image exposure amount required is larger than that for a line pattern due to a decrease in the contrast of light, resulting in a reduction in throughput.

The present invention solves the above-mentioned conventional problems, and reduces the number of N
An object of the present invention is to provide a photomask that can shape a contact hole pattern depending on the amount of light.

Means for Solving the Problems In order to achieve this object, the photomask of the present invention has a contact hole pattern portion having a lenticular shape,
A light-shielding film is provided on the other pattern surfaces.

Function: With this structure, since light is focused from a wide angle onto the contact hole portion on the photomask, the energy of the exposure light increases, the exposure time can be shortened, and the throughput can be increased.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to the drawings.

FIG. 1 shows a cross-sectional view of a photomask in one embodiment of the present invention. Referring to FIG. 1, 5 is a convex lens on the glass surface in which the contact hole portion on the glass surface is shaped like a convex lens, and 6 is a concave lens on the pattern surface in which the contact hole portion on the patterned surface is in the shape of a concave lens. Note that 1 is a glass substrate, 2 is a light-shielding film, 3 is a light source, and 4 is exposure light, which are the same as the conventional structure.

The operation of the photomask constructed as described above will be explained below.

First, the plane wave light source light 3 irradiated onto the convex lens 6 on the glass surface of the photomask is refracted by the convex lens shape, and is focused as a concave wavefront toward the concave lens 6 on the pattern surface. This condensed wavefront is refracted due to the concave lens shape on the pattern surface, and is irradiated onto the wafer as plane wave exposure light 4.

As described above, according to this embodiment, by providing a convex lens section on the glass surface of the contact hope portion of the photomask and a concave lens section on the pattern surface, it is possible to condense the light source light from a wide angle. The contact hole pattern can be shaped depending on the amount of exposure, and it is not easily affected by particles on the photomask.

Effects of the Invention As described above, the present invention has extremely high industrial value because it can shorten exposure time and increase throughput by providing a convex lens on the glass surface of the contact hole portion of a photomask and a concave lens on the pattern surface. This makes it possible to realize a high-performance photomask.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a photomask according to an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional photomask. 1... Gafnu substrate, 2... Light shielding film, 3
...Light source light, 4...Exposure light, 5...
... Convex lens on the Galanu surface, 6... Concave lens on the pattern surface.

Claims (1)

[Claims] A photomask characterized in that the glass portion of the contact hole pattern portion is lens-shaped, and the other pattern surfaces are provided with a light-shielding film.