JP2006261211A - Micro lens unit, solid-state imaging device, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a micro lens unit manufacturing method by which a micro lens unit having a good condensing efficiency can be manufactured easily. <P>SOLUTION: The method of manufacturing a micro lens unit which includes a plurality of convex micro lenses 3 and a concave micro lens 4 formed between the adjacent convex micro lenses 3 comprises a convex micro lens formation process wherein the convex micro lenses 3 are formed on a flat transparent layer consisting of a flattened layer 1 formed of an inorganic material and a micro lens material layer 2 stacked thereon (Fig.(b)); and a concave portion formation process wherein, after forming the convex micro lenses 3, a concave portion 4 which will become the concave micro lens is formed in the transparent layer between the convex micro lenses 3 by dry etching (Fig.(c)). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of manufacturing a microlens unit including a plurality of convex microlenses and a concave microlens formed between the convex microlenses.

  The area of one pixel tends to be further reduced due to the downsizing of the solid-state imaging device and the increase in the number of pixels. When the pixels are reduced, the light receiving area is reduced, so that sensitivity is lowered. However, reset noise and on-chip amplifier noise, which are main noise sources, do not change, and as a result, pixel reduction causes S / N degradation. Therefore, in order to ensure a sufficient S / N, it is necessary to reduce noise or improve the sensitivity of the solid-state imaging device. In order to improve the sensitivity, various structures (for example, Patent Document 1) have been proposed in which a microlens is provided on the pixel surface to increase the light collection efficiency to the photodiode.

FIG. 3 is a diagram for explaining a manufacturing process of the solid-state imaging device described in Patent Document 1.
The solid-state imaging device described in Patent Document 1 is manufactured as follows. First, the photodiode 102 is formed on the surface of the semiconductor substrate 101, and the photodiode 102 is covered with the planarizing film 103 made of silicon oxide. 105 is formed. Next, a resist is applied on the planarizing film 103 in which the concave portion 105 is formed, and exposure and development are performed to form a patterned resist 104 (FIG. 3A). Next, the resist 104 is reflowed and cured to form a convex microlens 104 ′ (FIG. 3B). As a result, the light incident between the adjacent microlenses 104 ′ is condensed on each photodiode 102 by the recess 105, so that the light collection efficiency can be increased.

JP 9-45884 A

  However, in the solid-state imaging device described in Patent Document 1, since the concave portion 105 having a function of collecting incident light between adjacent microlenses 104 ′ is formed by wet etching, the shape control is difficult. Further, since the shape of the microlens 104 ′ is determined by reflowing the resist 104, the shape control of the microlens 104 ′ is not easy, and the alignment between the microlens 104 ′ and the concave portion 105 is difficult.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for manufacturing a microlens unit by simply manufacturing a microlens unit with high light collection efficiency.

  A method for manufacturing a microlens unit according to the present invention is a method for manufacturing a microlens unit including a plurality of convex microlenses and a concave microlens formed between the convex microlenses. Forming a convex microlens on the transparent layer, and forming the convex microlens and then performing dry etching on the transparent layer between the convex microlenses. A recess forming step of forming a recess to be the concave microlens.

  According to this method, since the concave microlens is formed by dry etching, the shape of the concave microlens can be easily controlled, and a microlens unit with good light collection efficiency can be easily manufactured.

  The method for manufacturing a microlens unit of the present invention includes the transparent layer including an inorganic material layer and an organic material layer laminated on the inorganic material layer.

  According to this method, in the recess forming step, the recess can be formed by determining the etching conditions between the convex microlens and the organic material layer. More precise control can be performed.

  In the microlens unit manufacturing method of the present invention, the material of the organic material layer is different from the material of the convex microlens.

  According to this method, it becomes easier to control the shape of the recess.

  The method for producing a solid-state imaging device of the present invention is a method for producing a solid-state imaging device including a large number of photoelectric conversion elements, the step of forming the large number of photoelectric conversion elements on a semiconductor substrate surface, and the large number of photoelectric conversion elements Forming a microlens unit including a convex microlens corresponding to each of the plurality of photoelectric conversion elements and a concave microlens formed between the convex microlenses. The microlens unit forming step includes a convex microlens forming step of forming the convex microlens on a flat transparent layer laminated above the plurality of photoelectric conversion elements, and the convex After forming the microlenses, dry etching is performed to form the concave microlenses in the transparent layer between the convex microlenses. And a concave portion forming step of forming a section.

  According to this method, a highly sensitive solid-state imaging device can be easily manufactured.

  The manufacturing method of the solid-state imaging device of the present invention includes the transparent layer including an inorganic material layer and an organic material layer laminated on the inorganic material layer.

  According to this method, a highly sensitive solid-state imaging device can be manufactured more easily.

  In the solid-state imaging device manufacturing method of the present invention, the material of the organic material layer is different from the material of the convex microlens.

  According to this method, a highly sensitive solid-state imaging device can be manufactured more easily.

  The microlens unit of the present invention is a microlens unit including a plurality of convex microlenses and a concave microlens formed between the convex microlenses, and an inorganic material layer and the inorganic material A transparent layer including an organic material layer laminated on the layer, wherein the convex microlens is formed on the transparent layer, and a concave portion is formed in the transparent layer between the convex microlenses. The concave portion constitutes the concave microlens.

  According to this configuration, the light collection efficiency can be increased and the manufacture thereof is easy.

  In the microlens unit of the present invention, the material of the organic material layer is different from the material of the convex microlens.

  According to this structure, the manufacture is easier.

  The solid-state imaging device of the present invention is formed between a large number of photoelectric conversion elements formed on the surface of a semiconductor substrate, a convex microlens corresponding to each of the large number of photoelectric conversion elements, and the convex microlens. A solid-state imaging device having a microlens unit including a concave microlens, wherein the microlens unit includes a transparent layer including an inorganic material layer and an organic material layer laminated on the inorganic material layer. The convex microlens is formed on the transparent layer, a concave portion is formed in the transparent layer between the convex microlenses, and the concave portion constitutes the concave microlens.

  According to this configuration, high sensitivity can be realized and the manufacture thereof is easy.

  In the solid-state imaging device of the present invention, the material of the organic material layer is different from the material of the convex microlens.

  According to this structure, the manufacture is easier.

  According to the present invention, it is possible to easily manufacture a microlens unit with good light collection efficiency.

  Embodiments of the present invention will be described below with reference to the drawings. The microlens unit described in the present embodiment is used for, for example, a solid-state image sensor, and is arranged on a color filter of the solid-state image sensor, and includes a large number of photoelectric conversion elements formed on the semiconductor substrate surface of the solid-state image sensor. Each has a function of condensing light. Below, although the case where a microlens unit is used for a solid-state image sensor is explained, a use is not limited to this. The microlens unit described below includes a convex microlens corresponding to each of a large number of photoelectric conversion elements included in the solid-state imaging device, and a concave microlens formed between the convex microlenses. It is a configuration.

(First embodiment)
FIG. 1 is a diagram for explaining a manufacturing process of a microlens unit for explaining a first embodiment of the present invention.
Since the microlens unit is mounted on a solid-state imaging device, when manufacturing this microlens unit, first, a large number of photodiodes as photoelectric conversion elements are formed on the surface of a silicon semiconductor substrate, and then a color filter is formed on the upper layer. Form a layer. Up to this point, it can be manufactured by a conventional solid-state imaging device manufacturing process.

  Next, as shown in FIG. 1A, a transparent planarizing layer 1 made of an inorganic material such as silicon oxide is formed on the color filter layer, and an acrylic resin or the like is formed on the planarizing layer 1. A transparent and flat microlens material layer 2 (here, an acrylic resin) made of an organic material such as an organic resist material is formed. The planarizing layer 1 corresponds to an inorganic material layer in the claims, and the microlens material layer 2 corresponds to an organic material layer in the claims.

  Next, a resist made of an organic material that is a material for the convex microlens is applied on the microlens material layer 2, and exposure and development are performed to form a convex microlens pattern. For example, a pattern in which a plurality of rectangular unit resists 3 are arranged in a matrix is formed (FIG. 1A). The unit resist 3 is formed immediately above each opening of a large number of photodiodes, and the size thereof is set to be larger than, for example, the opening.

  Next, the unit resist 3 is subjected to a heat treatment at 120 to 140 ° C., for example, and reflowed, and the corners of the unit resist 3 are rounded by surface tension to form a spherical shape suitable for a convex microlens. And cured (FIG. 1B). By this step, the unit resist 3 cured in a spherical shape becomes a convex microlens having a function of condensing light at a photodiode opening located therebelow. Hereinafter, the unit resist 3 cured in a spherical shape is referred to as a convex microlens 3.

  Next, using the convex microlens 3 as a mask, dry etching (etching condition example: oxygen gas sealed at 1000 cc / min, pressure 70 Pa, power 1000 W, stage temperature 80 ° C. on which the wafer is placed) is performed. Concave portions 4 having a predetermined curvature are formed on the surface of the microlens material layer 2 between the convex microlenses 3 (FIG. 1C). The dry etching conditions may be set such that, for example, the surface parallel to the silicon substrate has an etching rate higher than that of other surfaces.

  The concave portion 4 functions to condense light incident between the adjacent convex microlenses 3 to the photodiode openings below the two microlenses 3 sandwiching the concave portion 4. The concave portion 4 is also referred to as a concave microlens 4. As the dry etching, chemical dry etching, ashing, or the like can be used.

  Through the above steps, the transparent layer including the planarizing layer 1 and the microlens material layer 2 laminated thereon, the convex microlens 3 formed on the transparent layer, and the microlens material of the transparent layer A solid-state imaging device including a microlens unit including a concave microlens 4 formed on the surface of the layer 2 is manufactured.

  According to the solid-state imaging device manufactured by this method, it is possible to increase the light collection efficiency to the photodiode opening, and thus it is possible to increase the sensitivity.

  In addition, according to the manufacturing process of the present embodiment, since the concave microlens 4 is formed by dry etching, the concave microlens is compared with the conventional method of forming the concave microlens by wet etching. 4 shape control becomes easy.

  Further, according to the manufacturing process of the present embodiment, the convex microlens 3 is formed first, and the concave microlens 4 is formed using the convex microlens 3 as a mask. Therefore, it is easier to align the convex microlenses 3 and the concave microlenses 4 than the conventional method of forming the microlenses after forming the microlenses.

  Further, according to the manufacturing process of the present embodiment, the convex microlens 3 is formed on the flat microlens material layer 2, and the concave portion 4 is formed by dry etching in this state. For this reason, etching conditions such as the gas species selectivity can be determined between the microlens material layer 2 and the convex microlens 3 made of the same organic material. The effect described above can also be obtained by directly forming the convex microlens 3 on the planarizing layer 1 and forming the concave portion 4 on the surface of the planarizing layer 1. According to the method described with reference to FIG. 5, the range of selection of the etching conditions is widened, and the shape control of the recesses 4 becomes easier.

  In addition, according to the manufacturing process of the present embodiment, since at least a part of the concave microlens 4 can be made of a microlens material, all of the concave microlenses are made of silicon oxide or the like. In comparison, the light condensing effect can be improved.

  In the above description, a resist made of an organic material is used as the material of the convex microlens 3. However, this material may be any transparent organic material such as an acrylic resin or an organic resist material. The material of the microlens material layer 2 and the material of the convex microlens 3 may be the same material or different materials. However, when different materials are used, the recess 4 is formed. In this dry etching process, the etching rate of the convex microlens 3 and the etching rate of the microlens material layer 2 can be controlled more easily than when the same material is used. For this reason, it is preferable that the material of the microlens material layer 2 and the material of the convex microlens 3 are different organic materials.

  In this embodiment, it is possible to produce a microlens unit without using the microlens material layer 2. In this case, the planarization layer 1 corresponds to a flat transparent layer in the claims. .

(Second embodiment)
In the present embodiment, a microlens unit in which the material of the microlens material layer 2 described in the first embodiment and the material of the convex microlens 3 are the same will be described.
FIG. 2 is a diagram for explaining a manufacturing process of a microlens unit for explaining a second embodiment of the present invention.
In manufacturing this microlens unit, first, a large number of photodiodes which are photoelectric conversion elements are formed on the surface of a silicon semiconductor substrate, and then a color filter layer is formed thereon. Then, as shown in FIG. 2A, a transparent planarizing layer 5 made of an inorganic material such as silicon oxide is formed on the color filter layer, and an acrylic resin or organic resin is formed on the planarizing layer 5. A transparent and flat microlens material layer 6 (here, an acrylic resin) made of an organic material such as a resist material is formed. The planarizing layer 5 corresponds to an inorganic material layer in the claims, and the microlens material layer 6 corresponds to an organic material layer in the claims.

  Next, a resist made of an organic material serving as a convex microlens material is applied on the microlens material layer 6, and exposure and development are performed to form a convex microlens pattern. For example, a pattern in which a plurality of rectangular unit resists 7 are arranged in a matrix is formed (FIG. 2A). The unit resist 7 is formed immediately above each opening of a large number of photodiodes, and the size thereof is set to be larger than, for example, the opening.

  Next, the unit resist 7 is subjected to a heat treatment at, for example, 120 to 140 ° C. to be reflowed, and the corners of the unit resist 7 are rounded by surface tension to form a spherical shape suitable for a convex microlens. And cured (FIG. 2 (b)).

  Next, etch back is performed to transfer the cured unit resist 7 to the microlens material layer 6 to form a convex microlens 8 (FIG. 2C). At this time, transfer is performed so that a flat portion having a certain thickness remains in the microlens material layer 6. By this step, the convex microlenses 8 are formed on the transparent layer including the planarizing layer 5 and the flat microlens material layer 6 laminated thereon.

  Next, dry etching is performed using the convex microlenses 8 as a mask, and concave portions 9 having a predetermined curvature are formed on the surface of the flat microlens material layer 6 between the many convex microlenses 8 ( FIG. 2 (d)). The dry etching conditions may be set such that, for example, the surface parallel to the silicon substrate has an etching rate higher than that of other surfaces.

  The concave portion 9 functions to condense light that has entered between adjacent convex microlenses 8 into the photodiode openings below the two microlenses 8 that sandwich the concave portion 9. As the dry etching, chemical dry etching, ashing, or the like can be used.

  Through the above steps, the transparent layer including the planarizing layer 5 and the microlens material layer 6 made of the same material as the convex microlenses 8 stacked thereon, and the convex formed on the transparent layer. The microlens unit including the microlens 8 and the concave microlens 9 formed on the surface of the microlens material layer 6 of the transparent layer is manufactured. According to this embodiment, among the effects described in the first embodiment, it is possible to obtain the same effects as those other than the effects obtained when the convex microlens and the microlens material layer are made of different materials. .

  In the present embodiment, transfer may be performed without leaving the microlens material layer 6 in FIG. In this case, the planarization layer 5 corresponds to the flat transparent layer in the claims.

The figure for demonstrating the manufacturing process of the micro lens unit for demonstrating 1st embodiment of this invention. The figure for demonstrating the manufacturing process of the micro lens unit for demonstrating 2nd embodiment of this invention. The figure for demonstrating the manufacturing process of the solid-state image sensor of patent document 1

Explanation of symbols

1, 5 Planarizing film 2, 6 Microlens material layer 3, 7 Unit resist 4, 9 Concave 8 Convex microlens

Claims (10)

A method of manufacturing a microlens unit comprising a plurality of convex microlenses and a concave microlens formed between the convex microlenses,
A convex microlens formation step of forming the convex microlens on a flat transparent layer;
Forming a concave portion that forms a concave portion that becomes the concave microlens in the transparent layer between the convex microlenses by performing dry etching after forming the convex microlens. Method. A method of manufacturing a microlens unit according to claim 1,
The method for manufacturing a microlens unit, wherein the transparent layer includes an inorganic material layer and an organic material layer laminated on the inorganic material layer. A method of manufacturing a microlens unit according to claim 2,
The material of the organic material layer is a manufacturing method of a microlens unit different from the material of the convex microlens. A manufacturing method of a solid-state imaging device including a large number of photoelectric conversion elements,
Forming a large number of photoelectric conversion elements on a semiconductor substrate surface;
A microlens unit including a convex microlens corresponding to each of the plurality of photoelectric conversion elements and a concave microlens formed between the convex microlenses above the plurality of photoelectric conversion elements; A microlens unit forming step to form,
The microlens unit forming step includes a convex microlens forming step of forming the convex microlens on a flat transparent layer laminated above the plurality of photoelectric conversion elements, and the convex microlens. A method of manufacturing a solid-state imaging device, comprising: forming a concave portion that becomes the concave microlens in the transparent layer between the convex microlenses by performing dry etching after the formation. It is a manufacturing method of the solid-state image sensing device according to claim 4,
The said transparent layer is a manufacturing method of the solid-state image sensor containing the inorganic material layer and the organic material layer laminated | stacked on the said inorganic material layer. It is a manufacturing method of the solid-state image sensing device according to claim 5,
The method of manufacturing a solid-state imaging device, wherein the material of the organic material layer is different from the material of the convex microlens. A microlens unit including a plurality of convex microlenses and a concave microlens formed between the convex microlenses,
A transparent layer comprising an inorganic material layer and an organic material layer laminated on the inorganic material layer;
The convex microlens is formed on the transparent layer,
A concave portion is formed in the transparent layer between the convex microlenses,
A microlens unit in which the concave portion constitutes the concave microlens. The microlens unit according to claim 7,
The material of the organic material layer is a microlens unit different from the material of the convex microlens. A plurality of photoelectric conversion elements formed on the surface of the semiconductor substrate; a convex microlens corresponding to each of the plurality of photoelectric conversion elements; and a concave microlens formed between the convex microlenses. A solid-state imaging device having a microlens unit,
The microlens unit includes a transparent layer including an inorganic material layer and an organic material layer laminated on the inorganic material layer,
The convex microlens is formed on the transparent layer,
A concave portion is formed in the transparent layer between the convex microlenses,
A solid-state imaging device in which the concave portion constitutes the concave microlens. The solid-state imaging device according to claim 9,
The material of the organic material layer is a solid-state imaging device different from the material of the convex microlens.

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