JP2005352142A - Method for manufacturing optical element array and mask for lithography - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily form an actual feature more similar to a designed feature. <P>SOLUTION: For example, in a method for manufacturing a microlens array having a plurality of microlenses to be used for a liquid crystal projector, a microlens array with fidelity to a designed feature is manufactured by using a gray scale mask 30 for lithography which has a plurality of correction portions 32 to form an enhancing feature (protruding features) on the borders of the plurality of microlenses and by gray scale lithography techniques and etching techniques. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical element array manufacturing method and a lithography mask, and more particularly to an optical element array manufacturing method and a lithography mask that can easily form an actual shape closer to a design shape.

  Microlens arrays are expected to increase in demand in the future as important optical elements in fine optics and other fields. Hereinafter, an application example to a liquid crystal projector (projection display device), which is one of typical demands, will be described.

  In recent years, liquid crystal projectors have been in the limelight as devices capable of easily viewing digital images by a large number of people. In particular, the high definition of the apparatus is remarkable and is rapidly evolving from VGA (640 × 480 dots) to SVGA (800 × 600 dots) and XGA (1024 × 768 dots).

  However, when the number of pixels in the liquid crystal panel is increased, especially in the active matrix type liquid crystal panel, the area occupied by parts other than the pixels, such as wiring and thin film transistors, becomes relatively large, and the area of the black matrix covering these parts increases. As a result, the area of pixels contributing to display is reduced, and the aperture ratio of the display element is lowered. Therefore, the aperture ratio is reduced, the screen becomes dark, and the image quality is lowered.

  Non-Patent Document 1 and Patent Document 1 disclose that a microlens array is provided on one surface of a liquid crystal panel (light valve) in order to prevent a decrease in aperture ratio due to an increase in the number of pixels. . A lithography mask is used for manufacturing the microlens array.

  FIG. 4 is a plan view showing a configuration of a conventional lithography mask 10. FIG. 5 is a perspective view showing a schematic configuration of the microlens array 20.

A microlens array 20 shown in FIG. 5 is an optical element array in which microlenses 21 _{1 to} 21 ₄ are arranged in a matrix (2 × 2 in the figure), and is used in the above-described liquid crystal projector and the like. The microlens array 20 is manufactured using the lithography mask 10 shown in FIG. 4 by a well-known gray scale lithography technique and etching technique. These microlenses 21 _{1 to} 21 ₄ have an aspherical concave shape.

Lithographic mask 10 shown in FIG. 4 is a mask to grayscale so that light transmittance in accordance with the shape of the microlens array 20 of the production object shown in the figure, the microlens 21 ₁ to 21 ₄ It has a corresponding gray scale section 11 _{1 to} 11 ₄ .

In the above configuration, when the microlens array 20 is manufactured, a resist is applied to a substrate (not shown), and then a lithography mask 10 is disposed above the substrate and irradiated with light or the like. Thereby, light is transmitted in accordance with the gray scale of the lithography mask 10. Next, when developed, an aspheric concave shape is formed in the resist in accordance with the sections 11 _{1 to} 11 ₄ of the lithography mask 10.

Next, the aspherical concave shape shown in FIGS. 5 and 6 is formed on the substrate by dry etching, and the microlens array 20 having the microlenses 21 _{1 to} 21 ₄ is manufactured.

Hiroshi Hamada, Fumiaki Funada: ("Special Feature: Liquid Crystal Projector with Significant Advancement; Increasing Brightness of Liquid Crystal Projector with Microlens Array"); Opplus E, August, 90-94 (1993) Japanese Patent Laid-Open No. 3-248125

  By the way, conventionally, when having a periodic structure like the microlens array 20, the boundary 20k between the microlenses becomes flat as shown in FIG. There was a problem that the actual shape line y was greatly shifted. That is, conventionally, it is difficult to form a microlens shape as designed.

  The present invention has been made in view of the above, and an object of the present invention is to provide an optical element array manufacturing method and a lithography mask that can easily form an actual shape closer to a design shape.

  In order to solve the above-described problems and achieve the object, the present invention is a method of manufacturing an optical element array having a plurality of optical elements, and for forming an emphasis shape at a boundary portion of the plurality of optical elements. The optical element array is manufactured using a grayscale lithography mask having a correction unit.

  Further, the present invention is a lithography mask used for manufacturing an optical element array having a plurality of optical elements, and has a correction unit for forming an emphasized shape at a boundary part of the plurality of optical elements. And

  According to the present invention, an optical element array is manufactured using a grayscale lithography mask having a correction portion for forming an emphasized shape at the boundary between a plurality of optical elements, so that the optical element array is closer to the design shape. There exists an effect that a real shape can be formed easily.

  Embodiments of an optical element array manufacturing method and a lithography mask according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  FIG. 1 is a plan view showing a configuration of a lithography mask 30 according to the first embodiment of the present invention. FIG. 2 is a microlens array 20 (see FIG. 5) manufactured using the lithography mask 30 shown in FIG. 1, and corresponds to the cross section taken along line BB ′ shown in FIG. It is a figure explaining the manufacturing condition of 20. FIG. In addition, the microlens array 20 in Example 1 has a curved surface different from that of the conventional example (see FIG. 6) as described later.

The lithography mask 30 shown in FIG. 1 is a mask having a light transmittance of gray scale as shown in FIG. 2 in accordance with the shape of the microlens array 20 (see FIG. 2) to be manufactured. ₁ to 21 ₄ has a compartment 31 _{1-31 4} gray scale corresponding to (see FIG. 5). Here, the lithography mask 30 has a plurality of correction portions 32 at the boundary between the sections. These correction parts 32 are made into the light transmittance for forming the some boundary part 22 of the protrusion shape as an emphasis shape shown in FIG.

Further, the light transmittance of the correction unit 32 is set so that the light transmittance changes stepwise according to the surface shape of the microlenses 21 _{1 to} 21 ₄ . Furthermore, in order to obtain an actual shape that is closer to the design shape, the difference between the light transmittance of the plurality of correction units 32 and the light transmittance of other portions may be set to a predetermined value or more. In this case, the light transmittance of the correction unit 32 is lower than the light transmittance of other portions.

A microlens array 20 shown in FIG. 2 is an optical element array in which microlenses 21 _{1 to} 21 ₄ are arranged in a matrix (for example, 2 × 2), and is used in the above-described liquid crystal projector and the like. The microlens array 20 is manufactured using a lithography mask 30 (see FIG. 1) by a well-known gray scale lithography technique and etching technique. Further, these microlenses 21 _{1 to} 21 ₄ have an aspherical concave shape as shown in FIG.

In the above configuration, when the microlens array 20 (see FIGS. 2 and 5) is manufactured, as described above, a resist is applied to a substrate (not shown), and then a lithography mask 30 is disposed above the substrate. Irradiate light. Thereby, light is transmitted in accordance with the gray scale of the lithography mask 30. Next, when developed, an aspherical concave shape is formed in the resist according to the sections 31 _{1 to} 31 ₄ of the lithography mask 30 and the plurality of correction portions 32.

Next, the aspherical concave shape shown in FIG. 3 is formed on the substrate by dry etching, and the microlens array 20 having the microlenses 21 _{1 to} 21 ₄ is manufactured. Here, as shown in FIG. 2, since a plurality of projecting boundary portions 22 are formed at the boundary portions between the microlenses, the actual shape line z becomes closer to the design shape line x, and the design is performed. An actual shape closer to the shape is formed.

  In the first embodiment, the lithography mask 30 for manufacturing the microlens array having a plurality of concave microlenses has been described. However, the present invention is not limited to this, and the micromask having a plurality of convex microlenses is described. The present invention is also applicable when manufacturing a lens array.

  In this case, the lithography mask is a gray scale mask having light transmission characteristics opposite to those of the lithography mask 30. Further, the correction portion in the lithography mask has a groove shape as an emphasized shape, contrary to the correction portion 32 (see FIG. 1). In this case, the light transmittance of the correction unit is higher than the light transmittance of other portions.

As described above, according to Example 1, a lithographic gray scale having a correcting portion for forming a protruding shape as a highlighted shape in the boundary portion of the plurality of micro lenses 31 ₁ to 31 ₄ of the lithographic mask 30 Since the micro lens array 20 is manufactured using the mask 30, an actual shape closer to the design shape can be easily formed.

In the first embodiment described above, a configuration example in which the correction unit 32 in which the light transmittance changes stepwise according to the surface shape of the microlenses 21 _{1 to} 21 ₄ is formed on the lithography mask 30 shown in FIG. However, as Example 2, the light transmittance of the correction unit may be set constant regardless of the surface shape of the microlenses 21 _{1 to} 21 ₄ .

FIG. 3 is a plan view showing a lithography mask 50 according to the second embodiment of the present invention. The lithography mask 50 shown in the figure is a mask whose light transmittance is gray scale as shown in the figure in accordance with the shape of the microlens array 20 (see FIG. 2) to be manufactured. ₁ to 21 ₄ has a compartment 51 _{1-51 4} gray scale corresponding to (see FIG. 5).

Here, the lithography mask 50 has a plurality of correction portions 52 at the boundary between the sections. As described in the first embodiment, these correction units 52 have light transmittance for forming an emphasis shape on the microlens array. Further, the light transmittance of the correction unit 52 is set to be constant regardless of the surface shape of the microlenses 21 _{1 to} 21 ₄ . Further, the widths of the plurality of correction units 52 are set to be equal to or lower than the process resolution, for example.

  In the first and second embodiments, the manufacturing method of the microlens array 20 has been described as an application example of the lithography mask 30 and the lithography mask 50. However, the present invention is not limited to this, and an inclined surface is formed at the boundary. The present invention is applicable to all methods for manufacturing a repeating array structure.

  As described above, the method for manufacturing an optical element array and the lithography mask according to the present invention are useful for forming an actual shape closer to the design shape, that is, for refinement.

FIG. 3 is a plan view showing a lithography mask 30 according to the first embodiment. The figure explaining the manufacturing condition corresponding to the B-B 'line view shown in FIG. FIG. 6 is a plan view showing a lithography mask 50 according to a second embodiment. The top view which shows the structure of the conventional mask 10 for lithography. FIG. 3 is a perspective view showing a schematic configuration of a microlens array 20. The figure explaining the manufacture condition corresponding to the A-A 'line | wire cutting shown in FIG.

Explanation of symbols

20 microlens array 21 ₁ to 21 ₄ microlens 30 a mask for lithography, 31 _{1-31 4} compartments, 32 correction unit, 50 a mask for lithography, 51 _{1-51 4} compartments, 52 correction unit

Claims (12)

A method of manufacturing an optical element array having a plurality of optical elements,
A method of manufacturing an optical element array, wherein the optical element array is manufactured using a grayscale lithography mask having a correction unit for forming an emphasis shape at a boundary part of the plurality of optical elements.   2. The method of manufacturing an optical element array according to claim 1, wherein, in the lithography mask, a difference between the light transmittance of the correction portion and the light transmittance of another portion is set to a predetermined value or more. .   3. The method of manufacturing an optical element array according to claim 1, wherein the light transmittance of the emphasized shape is set in a stepwise manner according to a surface shape of the optical element.   3. The method of manufacturing an optical element array according to claim 1, wherein the light transmittance of the emphasized shape is set to be constant regardless of a surface shape of the optical element.   The method for manufacturing an optical element array according to claim 1, wherein the emphasized shape is a protruding shape.   The method for manufacturing an optical element array according to claim 1, wherein the emphasized shape is a groove shape. A lithography mask used for manufacturing an optical element array having a plurality of optical elements,
Having a correction unit for forming an emphasized shape at a boundary between the plurality of optical elements;
A lithography mask characterized by the above.   The lithography mask according to claim 7, wherein a difference between the light transmittance of the correction unit and the light transmittance of another portion is set to a predetermined value or more.   9. The lithography mask according to claim 7, wherein the light transmittance of the emphasized shape is set in a stepwise manner according to the surface shape of the optical element.   The lithography mask according to claim 7 or 8, wherein the light transmittance of the emphasized shape is set to be constant regardless of a surface shape of the optical element.   The lithography mask according to claim 7, wherein the emphasized shape is a protruding shape.   The lithography mask according to claim 7, wherein the emphasized shape is a groove shape.

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