JP3321194B2 - Photo mask - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for transferring a predetermined pattern such as a lattice pattern onto a workpiece such as a photosensitive resin by irradiating light onto the workpiece. It relates to a photomask to be used.

[0002]

2. Description of the Related Art FIG. 4 is a schematic view showing a method of transferring a predetermined pattern to a photosensitive resin, which is an example of a member to be processed, using a conventional photomask. In the figure,
Reference numeral 1 denotes a conventionally used photomask, which is a light-impermeable material such as chrome on a transparent substrate 2 such as quartz.
For example, it is manufactured by drawing a lattice pattern 3 having a pitch of 180 μm. Reference numeral 4 denotes a photosensitive resin comprising, for example, a composition described in Japanese Patent Application No. 1-132286, which is adjusted to a thickness of about 3 μm on a glass substrate 5 by spin coating.

In a state where the photomask 1 is arranged above the photosensitive resin 4 at an appropriate interval L, light emitted from an extra high pressure mercury lamp (not shown) is converted into a parallel ray a, and then the parallel ray a The lattice pattern 3 is transferred to the photosensitive resin 4 by irradiating a with the photosensitive resin 4 through the photomask 1.

[0004]

In the above-mentioned conventional photomask, since the pattern 3 is made of a light-impermeable material such as chrome, the light beam a applied to the light-impermeable portion is exposed to light. It is not used, the light use efficiency is low, and the exposure time is long. Further, in order to transfer a desired sinusoidal pattern, it is necessary to precisely control the distance L between the photomask 1 and the photosensitive resin 4 by utilizing the diffraction and scattering of the irradiated light. By the way, the trial production test was repeated, and finally the above interval L was 90 μm.
m, the irradiation time was set to 10 minutes, and as a result, a trapezoidal wave pattern with a step of 0.5 μm was obtained. It is desired only by changing the conditions such as the interval L, the irradiation time, and the film thickness of the photosensitive resin 4. It was found that a sinusoidal pattern could not be obtained.

[0005] The reason is that the light reaction progresses from the front side of the photosensitive resin 4 and as a result, the light transmittance decreases due to the light reaction, thereby suppressing the light reaction on the back side. Transfer to the thick photosensitive resin 4 cannot be performed as specified. In addition, as the irradiation time becomes longer, a portion near the surface where the photoreactivity is reduced is irradiated with an excessive amount of light, and a side reaction such as an increase in coloring and light deterioration is likely to occur. Further, when transferring a cross-sectional structure inclined from the normal line of the photosensitive surface, a special technique such as proximity exposure is required, and there is a problem that the degree of freedom of the structure is low.

The present invention has been made in view of the above-mentioned circumstances, and not only can improve the efficiency of using light to shorten the exposure time, but also it is possible to reduce the coloration or the light intensity even if the workpiece is a thick photosensitive resin. An object of the present invention is to provide a photomask capable of transferring and manufacturing a predetermined pattern having excellent durability without accompanying a side reaction such as deterioration.

[0007]

In order to achieve the above object, a photomask according to the present invention transmits light from the back side to the front side, and forms a light beam on a workpiece disposed on the front side. Microlens array that exposes in a predetermined pattern
A photomask having a lens array for condensing and exposing according to the above-mentioned predetermined pattern , and having a light non-transmissive portion for emitting almost all of the light incident from the rear surface from the front surface. is the Sina potato.

[0008]

[Action] photomask according to the present invention, the formed because lens array over or Ranaru a predetermined pattern, because there is no opaque portion of the light, the light use efficiency is high. In addition, since the light intensity distribution can be appropriately controlled, a complicated pattern such as a sine wave can be easily obtained. Furthermore, light can also be condensed and exposed to the vicinity of the back surface on the workpiece, thereby allowing the light reaction to proceed from the back side of the workpiece,
It does not impair the light transmittance on the front side, so even for workpieces with a large thickness, side reactions such as coloring and light deterioration on the front side are suppressed, and a pattern with excellent durability is transferred. It can be made.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. FIG. 1 is a schematic diagram showing a method of performing a predetermined transfer by performing exposure in a predetermined pattern on a photosensitive resin as an example of a workpiece using a photomask according to the present invention. In FIG. 1, a photomask 10 is formed by forming a lens array 11 having a cross-sectional shape of a shape modulation type microlens on a substrate 12. This photomask 10 is, for example, an “ELECTRONICS”
LETTERS 31st January 1991
Vol. 27 No. No. 3 ". That is, a large number of cylindrical bodies made of a photoresist are formed on a substrate 12 such as quartz or glass by lithography technology, and these cylindrical bodies are heated and melted to form a substantially spherical shape as shown in FIGS. A lens array 11 in which many small lenses 11a are arranged is manufactured. Reference numeral 4 denotes a photosensitive resin comprising, for example, a composition described in Japanese Patent Application No. 1-132286, which is adjusted to a thickness of about 3 μm on a glass substrate 5 by spin coating.

With the photomask 10 arranged above the photosensitive resin 4 at an appropriate interval L, light emitted from an unshown ultra-high pressure mercury lamp is converted into a parallel ray a, and then the parallel ray a a is passed through the photomask 10 from the back side (upper side), and is irradiated to the photosensitive resin 4 located on the front side (lower side). Thereby, a three-dimensional pattern is transferred onto the photosensitive resin 4 in accordance with the light intensity distribution accompanying the light condensing action of the lens array 11 of the photomask 10, and a desired sinusoidal grating is formed on the substrate 5. Then, a diffraction grating is produced.

As described above, the photomask 10 comprising the lens array 11 having a microlens-type cross-sectional shape.
Is used, it is possible to effectively use the entire light amount, increase the light use efficiency, and shorten the exposure time.
Also, the distance L between the photomask 10 and the photosensitive resin 4 is
By setting the focal point of the light on the back side of the photosensitive resin 4, the photoreaction on the back side is promoted, whereby excessive light is emitted on the surface portion where the coloring and the photoreaction have occurred. A side reaction such as light deterioration due to irradiation can be suppressed, and a pattern having excellent durability can be transferred.

Embodiment 2 FIG. FIG. 3 is a schematic view showing a method of transferring a predetermined pattern to a photosensitive resin using another photomask according to the present invention. This embodiment is different from the first embodiment in that the photomask 10A
Has the cross-sectional shape of the refractive index modulation type microlens. This photomask 10A has, for example, “O
PlusE. January 1987, p. 73 ". That is, a mask pattern having a large number of circular openings is formed on a substrate 12 such as quartz or glass by lithography technology, ion exchange is caused to occur through the circular openings, and a three-dimensional refractive index distribution 13 is formed. It becomes.

The photomask 10A as described above is fired from an unshown ultra-high pressure mercury lamp with the photomask 10A arranged above the photosensitive resin 4 at an appropriate distance L in the same manner as in the first embodiment. The resulting light is converted into a parallel light beam a, and the parallel light beam a is irradiated on the photosensitive resin 4 through the photomask 10A, thereby forming the photomask 10A.
The three-dimensional pattern is transferred onto the photosensitive resin 4 in accordance with the light intensity distribution accompanying the light condensing action of the mask pattern 13 to form a desired sinusoidal lattice.

In the case of the second embodiment, as in the case of the first embodiment, it is possible to solve various problems that have occurred when transferring is performed using a conventional photomask.

The microlens in the present invention is not limited to the form modulation type and the refractive index modulation type shown in the above embodiment, but may be any form such as a circular or lenticular type. You may use what combined two or more. Further, products to which a pattern is transferred using the photomask of the present invention (transfer application products) include microlenses,
There are spatial frequency filters, projection screens and the like.

[0016]

As described above, since the photomask of the present invention has no light-impermeable portions, the light utilization efficiency can be increased and the exposure time can be shortened. In addition, since the light intensity distribution can be arbitrarily controlled, a complicated three-dimensional pattern such as a sine wave can be easily formed. Furthermore, by focusing and exposing near the back surface of the workpiece, the light reaction proceeds from the back side of the workpiece, and the light transmittance of the front side is not impaired, and the workpiece having a large thickness is not damaged. Also, a predetermined pattern can be reliably and easily transferred to a workpiece without accompanying side reactions such as coloring and light deterioration on the surface side. In addition, by controlling the cross-sectional structure and refractive index distribution of the micro lens,
The transfer of the cross-sectional structure inclined from the normal line is also possible, and the range of transfer application products can be expanded.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a method of performing a predetermined transfer by performing a predetermined pattern exposure on a photosensitive resin as an example of a member to be processed using a photomask according to the present invention.

FIG. 2 is a plan view of the photomask shown in FIG.

FIG. 3 shows another photomask according to the present invention,
FIG. 4 is a schematic view illustrating a method of transferring a predetermined pattern to a photosensitive resin.

FIG. 4 is a schematic view showing a method of transferring a predetermined pattern to a photosensitive resin as an example of a workpiece using a conventional photomask.

[Explanation of symbols]

4: photosensitive resin (an example of a member to be processed), 10, 10A ...
Photomask, 11: lens array, 13: mask pattern.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03F 1/08 H01L 21/027

Claims (1)

(57) [Claims] (1) transmitting light from the back side to the front side,
A photomask, which is a microlens array for performing exposure in a predetermined pattern on a workpiece disposed on the front side, comprising a lens array for condensing and exposing according to the predetermined pattern , and emits almost all of the light entering from the front from the stomach such have opacities of light
Off Otomasuku.