JP2000332226A - Microlens array and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide structure of a microlens array, which can increase the number of picture elements of an image sensing device or improve light condensing efficiency, and a manufacturing method of the array. SOLUTION: This manufacturing method of a microlens array consists of a process for forming a plurality of thermoplastic resins 2a of a first pattern on a substrate 1 interposing air gaps having a specified width, a process for transforming the thermoplastic resin to a lens type by heating the thermoplastic resin 2a of the first pattern, a process forming a plurality of thermoplastic resins 6a of a second pattern in the air gaps between the thermoplastic resins 2a of the first pattern, in such a manner that a part overlaps the thermoplastic resin of the first pattern, and a process transforming the thermoplastic resin to a lens type by heating the thermoplastic resin 6a of the second pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a microlens, and more particularly, to a microlens array convenient for condensing light on a plurality of objects and a method of manufacturing the same.

[0002]

2. Description of the Related Art In a solid-state image pickup device such as a CCD image sensor, a minute microlens is provided on each of a plurality of light receiving elements such as photodiodes formed on a semiconductor substrate. The light condensed by the microlens is efficiently guided to the light receiving region of the light receiving element. The micro lens array is composed of multiple light receiving elements (pixels)
And a connection of a plurality of microlenses arranged corresponding to.

[0003]

FIG. 6 schematically shows a part of a conventional microlens array. FIG. 6A is a plan view, and FIG. 6B is a longitudinal sectional view taken along line II ′ of FIG. 6A. The plurality of microlenses 20 are formed on a semiconductor substrate 21. On the semiconductor substrate 21, for example, a photodiode 22 and a CCD (not shown) are formed. The micro lens 20 is arranged so as to condense light on a light receiving area of the photodiode 22.

[0006] In the conventional microlens array shown in FIG. 6, an ineffective area 23 which does not serve as a lens is formed widely between adjacent microlenses. In such a structure, the ratio of the substantial light receiving area to the entire area of the image sensor decreases, so that the light use efficiency is low. Further, since the arrangement of the light receiving elements is determined by the arrangement interval of the microlenses, there is a disadvantageous limitation in increasing the density of the pixels of the imaging element.

An object of the present invention is to provide a microlens array capable of increasing the number of pixels of an image pickup device or increasing the light collection efficiency or a method of manufacturing the same.

[0006]

According to one aspect of the present invention, a first region in which a plurality of convex lenses of light transmissive material are arranged at intervals, and a plurality of convex lenses of light transmissive material are spaced apart. And a second region arranged with
The first and second regions are arranged such that the convex lens of the region and the convex lens of the second region are alternately arranged in a checkered pattern, and the convex lens of the adjacent first region and the second lens are arranged in a checkered pattern. There is provided a microlens array having a portion where a convex lens in a region partially overlaps with each other.

According to another aspect of the present invention, a step of forming a plurality of first-pattern thermoplastic resins on a substrate with a gap having a predetermined width therebetween; Heating the resin to deform the thermoplastic resin into a lens shape, and a gap between the thermoplastic resin of the first pattern so that a part thereof overlaps the thermoplastic resin of the first pattern. Forming a plurality of second-pattern thermoplastic resins, and heating the second-pattern thermoplastic resin to deform the thermoplastic resin into a lens shape. Is provided.

Since the adjacent microlenses are formed so as to have portions overlapping each other, the ineffective area is minimized.

[0009]

1 to 4 show steps of a method for manufacturing a microlens array according to an embodiment of the present invention. In each of these figures, (a) is a plan view of a part of the microlens array, and (b) is a longitudinal sectional view taken along line II ′ of the plan view (a). Note that, in these figures, details of a substrate of the semiconductor imaging element formed below the microlens array are omitted for easy understanding. Details of the substrate will be described later with reference to FIG.

First, a transparent (light transmitting) thermoplastic (thermo-softening) and photosensitive resin material is shown on the substrate 1 by, for example, photolithography or another coating process as shown in FIG. The resin 2 is formed in such a plane pattern. The resin 2 is formed on the light receiving region of the first photodiode 4 using, for example, polyglycidyl methacrylate (PGMA) of an acrylic resin. FIG.
(B) is a cross-sectional view, in which a resin 2 having a substantially columnar shape is formed with a gap 3 interposed therebetween. In other words, a pattern in which areas with the thermoplastic resin 2 and areas 3 without the thermoplastic resin 2 are alternately arranged in a checkered pattern.

Next, the thermoplastic resin 2 is heated at about 180 ° C. for 30 minutes.
After heating for 2 seconds, the thermoplastic resin is melted and the corners are deformed to be rounded, and deformed into the convex lens-shaped microlenses 2a as shown in FIG. 2B. The thermoplastic resin 2 has thermosetting properties, and after cooling after thermal deformation, hardens and does not deform when heated thereafter. FIG. 2A is drawn concentrically in order to represent the micro lens 2a as a convex lens.

Next, the same thermoplastic and photosensitive resin materials are applied to the gaps 3 of the microlens array obtained in the step of FIG. 2 by, for example, a photolithography process or another coating process, as shown in FIG. The resin 6 is formed in a simple planar pattern. The resin 6 is formed on the light receiving area of the second photodiode 5. The planar shape of the resin 6 is a quadrangle. As shown in FIG. 3B, it is formed so as to overlap with the ends of the already formed microlenses 2a on both sides.

Finally, as in the first heating condition, the thermoplastic resin 6 is heated at about 180 ° C. for 30 seconds to melt the thermoplastic resin 6 and deform the rounded corners, as shown in FIG. 4B. It is transformed into such a convex lens-shaped microlens 6a. The heating does not deform the convex lens 2a formed by the first heating.

As a result, the region of the convex lens 2a and the region of the convex lens 6a are arranged so as to overlap with each other so as to have a portion 7 which partially overlaps with each other. The area is reduced to a minimum. When such a method of manufacturing a microlens array is adopted, it is preferable to use a pixel array such as a Bayer array in a color image sensor, for example. For example, the first micro lens 2a for forming a lens is a lens for a green (G) pixel, and the micro lens 6a for the next lens is formed.
If a is a lens for the red (R) pixel and the blue (B) pixel, a lens having the same condition for each color is formed at a time, and the color characteristics are uniform, which is preferable in characteristics. Conversely, the micro lens 2a may be a lens for a red pixel and a blue pixel, and the micro lens 6a may be a lens for a green pixel.

FIG. 5 is a sectional view of a part of the CCD color image sensor according to the present embodiment. An n-type semiconductor region 31 and a charge-coupled device (CCD) 33 composed of an n-type semiconductor region are formed in a p-type semiconductor region 10 of a semiconductor substrate. The pn junction between the semiconductor regions 10 and 31 forms a photodiode. A p-type region may be further formed on the surface of the n-type semiconductor region 31 to form a buried pn junction.
A channel stop 3 made of a p-type semiconductor region is provided between the photodiode region 31 and the right CCD region 33.
2 are formed.

The transfer gate TG is formed so as to protrude from above the CCD 33 toward the photodiode, and can transfer charges from the photodiode region 31 to the CCD region 33. Photodiode area 3
A PSG layer 11 that transmits light is formed on the first layer 1. A
The light shielding film 12 made of the material 1
The upper part of the region other than the photodiode region 31 is covered so that light is incident only on the region. A flattening layer 13 is formed thereon, and a color filter 14 is further formed thereon. Further, on the flattening layer 15 formed on the color filter 14, the microlenses 2a and 6a are formed so as to overlap. For example, under the micro lens 2a,
A green color filter 14 is formed, and the micro lens 6
A red or blue color filter 14 is formed below a.

The present invention has been described in connection with the preferred embodiments.
The present invention is not limited to these. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

[0018]

As described above, according to the present invention,
Since the adjacent microlenses are formed so as to have portions overlapping each other, the ineffective area is reduced to a minimum and the number of pixels of the image sensor can be increased. In addition, the light collection efficiency of the lens can be increased.

[Brief description of the drawings]

1A and 1B are a plan view and a cross-sectional view illustrating steps of a method for manufacturing a microlens array according to an embodiment of the present invention.

2A and 2B are a plan view and a cross-sectional view illustrating another process of the method for manufacturing a microlens array according to the embodiment of the present invention.

3A and 3B are a plan view and a cross-sectional view illustrating still another step of the method of manufacturing the microlens array according to the embodiment of the present invention.

FIGS. 4A and 4B are a plan view and a cross-sectional view illustrating a final step of a method for manufacturing a microlens array according to an embodiment of the present invention.

FIG. 5 is a partial cross-sectional view of a CCD color image sensor according to an embodiment of the present invention.

FIG. 6 is a plan view and a sectional view showing a structure of a microlens array according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2, 6 Convex part made of thermoplastic resin 3 Void 4, 5 Light-receiving part 2a, 6a Convex lens (micro lens) 7 Overlapping part 10 Semiconductor substrate 11 PSG 12 Light-shielding film 13, 15 Flattening film 15 Color filter 20 Conventional micro Lens 21 Semiconductor substrate 22 Photodiode 23 Invalid area 31 Photodiode area 32 Channel stop 33 Charge coupled device (CCD)

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 4M118 AA01 AB01 BA10 CA02 CA04 FA06 FA26 FA35 GB11 GC08 GD02 GD04 GD06 GD07 5C024 AA01 CA11 CA12 CA31 EA04 FA12 GA51

Claims (6)

[Claims] A first region in which a plurality of convex lenses of a light-transmitting material are arranged at intervals; and a second region in which a plurality of convex lenses of a light-transmitting material are arranged at intervals. The first and second regions are arranged so that the convex lenses of the first region and the convex lenses of the second region are alternately arranged in a checkered pattern, and the convex lenses of the adjacent first region are arranged. And a convex lens in the second region partially overlaps with each other. 2. A step of forming a plurality of first-pattern thermoplastic resins on a substrate with a gap having a predetermined width interposed therebetween, and heating the first-pattern thermoplastic resin to form the thermoplastic resin. And forming a plurality of second patterns in the gaps between the thermoplastic resins of the first pattern so that a portion thereof overlaps the thermoplastic resin of the first pattern. A method for manufacturing a microlens array, comprising: a step of forming a thermoplastic resin; and a step of heating the thermoplastic resin of the second pattern to deform the thermoplastic resin into a lens shape. 3. The thermoplastic resin of the first pattern,
3. The method according to claim 2, wherein the thermoplastic resin regions and the void regions are alternately arranged in a checkered pattern. 4. The thermoplastic resin of the second pattern,
4. The method of manufacturing a microlens array according to claim 2, wherein the planar shape is a quadrangle. 5. The substrate according to claim 2, wherein the substrate is a semiconductor substrate on which a plurality of light receiving elements are formed, and the thermoplastic resin of the first and second patterns is disposed on the light receiving elements.
The method for producing a microlens array according to any one of the above. 6. The semiconductor substrate has, on each of the light receiving elements, one of a red filter, a green filter, and a blue filter, and the thermoplastic resin of the first pattern is formed of the green filter. And the second pattern of thermoplastic resin is formed on the red and blue filters, or the first pattern of thermoplastic resin is formed on the red and blue filters and 6. The method according to claim 5, wherein the thermoplastic resin of the second pattern is formed on the green filter.