JP2003249634A - Solid imaging device and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To permit designing an inlayer lens so as to have a desired configuration. <P>SOLUTION: A lens film 12 is formed on a light shielding film 11 as shown in a diagram 3A. A photosensitive material is applied on the lens film 12 as shown in a diagram 3B whereby the photosensitive film 12 having an opening 18 on the upper part of a photosensor 6 is formed. The lens film 12, on which the photosensitive film 17 is applied, is processed by etching to form a concave lens 13. The photosensitive film 17 formed on the lens film 12 is removed. A flattening film 14 is formed on the lens film 12, from which the photosensitive film 17 is removed. A filter 15 is formed on the flattening film 14. An on-chip lens 16 is formed on the filter 15. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image sensor and a method for manufacturing the same, and more particularly to a solid-state image sensor having an in-layer lens and a method for manufacturing the same.

[0002]

2. Description of the Related Art As the size of a solid-state image pickup device is reduced, a light receiving area is reduced, resulting in deterioration of characteristics such as a decrease in sensitivity and an increase in smear. In order to solve this problem, it has been proposed to provide an on-chip lens on the filter to increase the light collection rate.

However, in recent years, further miniaturization of solid-state image pickup devices has progressed, and further improvement of the light collection rate is required. Therefore, in the recent solid-state image sensor, as shown in FIG. 20, a concave lens 105 is provided directly above each photo sensor 101.
Film 10 having a concave or convex shape so that
4 is formed on the light-shielding film 103, and a filter 107, a flattening film 106, and a protective film 104 made of materials having different refractive indexes are stacked on the light-shielding film 103 to improve the collection efficiency. .

[0004]

However, since it is difficult to design the curvature of the concave lens 105 into a desired shape in the conventional method for manufacturing a solid-state image pickup device, the light collection rate on the surface of the photosensor 101 is sufficient. I was not able to raise it to, and the smear component increased. This is because in the conventional method for manufacturing a solid-state image sensor, the shape of the concave lens 105 is formed by heat melting (reflow).
This is because the shape depends on the shape of the transfer electrode 102 and the unit cell size.

Therefore, an object of the present invention is to provide a solid-state image pickup device capable of improving the light collection rate and a method for manufacturing the same.

[0006]

In order to solve the above-mentioned problems, the first invention of the present application is a solid-state imaging device having an in-layer lens, wherein the in-layer lens has an etching mask on the lens film. A solid-state image sensor formed by etching a lens film using an etching mask as a mask.

According to the first invention of the present application, the inner lens is
Since an etching mask is applied on the lens film and the lens film is etched using the etching mask as a mask, the shape is not limited by the shape of the transfer electrode and the size of the unit cell. A lens can be provided in the solid-state image sensor. Therefore, it is possible to provide the solid-state imaging device with the intralayer lens having the designed curvature.

A second invention of the present application is a method of manufacturing a solid-state image pickup device having an intralayer lens, wherein an etching mask is used.
A method for manufacturing a solid-state imaging device, comprising: a step of forming on the lens film; a step of etching the lens film using the etching mask as a mask; and a step of removing the etching mask formed on the lens film. Is.

According to the second aspect of the present invention, since the intralayer lens is formed by etching, the intralayer lens can be formed without being limited by the shape of the transfer electrode and the size of the unit cell. Therefore, the curvature of the intralayer lens can be designed.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a solid-state image sensor 1 according to the first embodiment of the present invention.
As shown in FIG. 1, the solid-state imaging device 1 includes an imaging area 2
A horizontal transfer register 3 having a CCD structure arranged at one end of the image pickup area 2, an output section 4 connected to the final stage of the horizontal register, and a peripheral area 5 having a bus line and the like.
With.

The image pickup area 2 includes a plurality of photosensors 6 arranged in a matrix and a plurality of vertical transfer registers 7 having a CCD structure corresponding to each photosensor array.
The photo sensor 6 is for photoelectrically converting light incident on the solid-state image sensor 1. The vertical transfer register 7 is for transferring the signal charges photoelectrically converted in the photosensor 6 to the horizontal transfer register 3.

The horizontal transfer register 3 is for transferring the signal charges supplied from the image pickup area 2, that is, the vertical transfer register 7 to the output section 4. The output unit 4 is for supplying the signal charges transferred from the horizontal transfer register 3 to a signal processing unit (not shown).

FIG. 2 is a sectional view taken along the line segment AA in FIG. As shown in FIG. 2, the solid-state imaging device 1 includes a photo sensor 6, a vertical transfer register 7, a light shielding film 11, a lens film 12, a concave lens 13, a flattening film 14, a filter 15, and an on-chip lens 16 (On Chip Lens (OCL )).

A lens film 12 formed on the light-shielding film 11.
Is a film for forming the concave lens 13. The flattening film 14 formed on the lens film 12 is for mounting the filter 15. Here, the lens film 12 is composed of an oxide film material, preferably an oxide film material such as SOG having a refractive index of 1.4 to 1.6.

The concave lens 13 efficiently supplies the light incident on the solid-state image pickup device 1 to the photosensor 6,
This is for improving the sensitivity of the solid-state imaging device 1.
The concave lens 13 has a shape that is recessed in the direction of the photosensors 6 and is arranged above each photosensor 6.

A filter 15 formed on the flattening film 14.
Is for outputting a signal having color information from the solid-state imaging device 1.

The on-chip lens 16 formed on the filter 15 is for improving the sensitivity of the solid-state image pickup device 1 by efficiently supplying the light incident on the solid-state image pickup device 1 to the photosensor 6. . The on-chip lens 16 is a convex lens having a shape protruding with respect to the light incident on the solid-state image sensor 1, and is arranged above each photosensor 6, that is, directly above the concave lens 13.

Next, a method of manufacturing the solid-state image sensor according to the first embodiment of the present invention will be described.

First, as shown in FIG. 3A, a lens film 12 is formed on the light shielding film 11. Then, as shown in FIG. 3B, a photosensitive material (etching mask) 17 having an opening 18 is formed above the photosensor 6 by applying a photosensitive material on the lens film 12.

FIG. 4 is a top view showing an example of the shape of the photosensitive film 17. As shown in FIG. 4, a photosensitive film 17 having grid-shaped openings 18 is formed on the lens film 12. Here, the opening 18 is located on a portion forming the concave lens 13, that is, on the photo sensor 6.

After that, the lens film 12 is etched using the photosensitive film 17 as a mask. Thereby, the concave lens 13
Is formed. Here, the etching is etching in which anisotropic etching, isotropic etching, anisotropic etching and isotropic etching are combined. Which of these etchings is selected is determined by the shape of the concave lens formed on the lens film 12. When selecting a combination of isotropic etching and anisotropic etching, the order of performing these etchings may be selected.

FIG. 5 shows an example of the shape of the concave lens 13 formed by anisotropically etching the lens film 12. As shown in FIG. 5, using the photosensitive film 17 as a mask,
By anisotropically etching the lens film 12, an elliptical concave lens 13a can be formed.

FIG. 6 shows an example of the shape of the concave lens 13 formed by subjecting the lens film 12 to isotropic etching such as wet etching or dry etching. As shown in FIG. 6, the lens film 12 is formed using the photosensitive film 17 as a mask.
Isotropically etched to form a hemispherical concave lens 13b.

FIG. 7 shows an example of the shape of the concave lens 13 formed by anisotropically etching the lens film 12 and then isotropically etching it. FIG. 8 shows the lens film 12
This is an example of the shape of the concave lens 13 formed by isotropically etching and then anisotropically etching. As shown in FIGS. 7 and 8, by combining anisotropic etching and isotropic etching, it is possible to obtain the shape of the concave lens 13 that cannot be obtained by only one etching. Moreover, the concave lens 12 having different shapes can be formed by changing the order of anisotropic etching and isotropic etching.

Next, as shown in FIG. 3C, the lens film 12
The photosensitive film 17 formed above is removed. Then, the planarizing film 14 is formed on the lens film 12 from which the photosensitive film 17 is removed.
To form.

Next, a filter 15 is formed on the flattening film 14. Then, the on-chip lens 1 is placed on the filter 15.
6 is formed.

In the above embodiment, the material of the lens film 12, the exposure size of the photosensitive film 17, and the etching conditions need to be optimized according to the type of the solid-state image pickup device 1 (cell size, design, etc.).

Therefore, the first embodiment of the present invention has the following effects. The photosensitive film 17 is formed on the lens film 12, and the photosensitive film 17 is used as a mask to form the lens film 12.
Since the concave lens 13 is formed by etching, the concave lens 13 can be formed without being limited to the shapes of the vertical transfer register 7 and the inter-pixel electrode. Therefore, the curvature of the concave lens 13 can be designed in a desired shape.
That is, the light collection rate on the surface of the photo sensor 6 can be improved. Moreover, the sensitivity of the solid-state image sensor can be improved. Furthermore, the smear component can be reduced.

Next, a second embodiment of the present invention will be described. In the second embodiment of the present invention, a lens film is formed by laminating a plurality of films having different etching rates on a light-shielding film, and the lens film is formed by etching due to the difference in the etching rate of each layer forming the film. It controls the shape of the concave lens.

FIG. 9 is a sectional view showing an example of the schematic arrangement of a solid-state image pickup device according to the second embodiment of the present invention. Here, as an example, the lens film 12 is the first lens film 12.
a, the second lens film 12b and the third lens film 12c
It is shown that it is composed of The first lens film 12a, the second lens film 12b, and the third lens film 1
2c is a film having a different etching rate from each other. The first lens film 12a is, for example, SiN. The second lens film 12b is, for example, SiON. The third lens 12c is, for example, SOG.

The structure of the solid-state image sensor other than this is the same as the structure of the solid-state image sensor according to the first embodiment described above, and the description thereof will be omitted.

Next explained is a method of manufacturing a solid-state image sensor according to the second embodiment of the invention. Here, the case where the lens film 12 is formed by stacking three films having different etching rates is shown as an example.

First, three etching rates are different from each other.
One film, that is, the first lens film 12a, the second lens film 12b, and the third lens film 12c are sequentially laminated on the light shielding film 11 to form the lens film 12. Where the first
The materials and film thicknesses of the lens film 12a, the second lens film 12b, and the third lens film 12c are selected according to the shape of the concave lens 13 formed on the photosensor 12.

Next, a photosensitive material is applied onto the lens film 12 to form a photosensitive film (etching mask) having an opening above the photosensor 6. For example, as in the first embodiment, the photosensitive film 17 shown in FIG. 4 is formed on the lens film 12.

Then, the lens film 12 is etched using the photosensitive film 17 as a mask. Here, the etching is, for example, isotropic etching, anisotropic etching, or etching in which isotropic etching and anisotropic etching are combined.

Other than this, the method of manufacturing the solid-state image sensor is the same as the method of manufacturing the solid-state image sensor according to the first embodiment described above, and therefore the description thereof will be omitted.

FIG. 10A shows a first example of the lens film 12 formed on the light shielding film 11. As shown in FIG. 10A,
The first lens film 12a is made of SiN. The second lens film 12b is made of SiON. The third lens film 12c is made of SOG.

FIG. 10B shows an example in which the lens film 12 having the structure shown in FIG. 10A is isotropically etched to form a concave lens. As shown in FIG. 10B, the concave lens 13c having a low curvature is obtained by using the lens film 12 having the configuration shown in the first example.
You can see that you can design.

FIG. 11A shows a second example of the lens film formed on the light shielding film 11. As shown in FIG. 11A, the first
The lens film 12a of SOG is made of SOG. Second lens film 1
2b is made of SiON. The third lens film 12c is made of Si
It consists of N.

FIG. 11B shows an example in which the lens film 12 having the structure shown in FIG. 11A is isotropically etched to form a concave lens. From FIG. 11B, the concave lens 13d having a high curvature can be obtained by using the lens film 12 having the configuration shown in the second example.
You can see that you can design.

Therefore, the second embodiment of the present invention has the following effects. A lens film 12 is formed by stacking a plurality of films having different etching rates on the light-shielding film 11, and a photosensitive film is formed on the lens film 12 to form a photosensitive film 17. 17
Is used as a mask to etch the lens film 12,
A single layer lens film having the same etching rate is used as the light shielding film 11
It is possible to realize a lens shape that cannot be obtained by forming it above. That is, it is possible to obtain a concave lens shape that cannot be obtained in the first embodiment.

Next explained is the third embodiment of the invention. The solid-state image sensor according to the third embodiment of the present invention is one in which a high refractive index film is formed on the concave lens of the solid-state image sensor according to the first embodiment described above. here,
The high refractive index film formed on the concave lens is a film made of a material having a higher refractive index than the material forming the lens film, that is,
A film having a higher refractive index than an oxide film system, such as SiN,
It is formed by applying SiON, SOG, polyimide, SiO, thermosetting resin or the like to the concave lens, or by forming a film on the concave lens with these materials.

FIG. 12 shows an example in which a high refractive index film is formed on the concave lens by applying a material having a higher refractive index than the oxide film type material to the concave lens. As shown in FIG. 12, the high refractive index film 19 has a shape embedded in the concave lens 13.

FIG. 13 shows an example in which a high refractive index film is formed on a concave lens by using a material having a higher refractive index than an oxide film type material. As shown in FIG. 13, the high-refractive index film 20 having a substantially uniform film thickness is formed over the entire surface of the lens film 12.

Except for this, the description is omitted because it is the same as that of the first embodiment described above.

Therefore, the third embodiment of the present invention has the following effects in addition to the effects of the first embodiment. In order to embed a high-refractive-index film in the concave surface of the concave lens 13 or to form a high-refractive-index film in the concave surface of the concave lens 13, the solid-state image sensor 1 compared to the first embodiment.
It is possible to suppress the reflection component of the light incident on. That is, the light collection rate can be improved as compared with the first embodiment.

Next explained is the fourth embodiment of the invention. In the fourth embodiment of the present invention, a lens film is etched a plurality of times by using a plurality of photosensitive films having different mask patterns. The solid-state image sensor according to the first embodiment has substantially the same configuration as that of the solid-state image sensor according to the first embodiment described above, and thus the illustration thereof is omitted.
The corresponding portions will be described using the same reference numerals.

A method of manufacturing a solid-state image sensor according to the fourth embodiment of the present invention will be described below. here,
The case where the lens film 12 is etched using the photosensitive film as a mask and then the lens film 12 is etched using an etching mask having a mask pattern different from that of the photosensitive film as an example will be described. Specifically, after the lens film 12 is etched by using the photosensitive film having the stripe-shaped opening parallel to the vertical transfer register 7 as a mask, the photosensitive film 12 having the lattice-shaped opening is used as the mask to form the lens film 12.
As an example, the case of etching again is shown.

First, the lens film 12 is formed on the light shielding film 11. Here, the lens film 12 is composed of an oxide film material, preferably an oxide film material such as SOG having a refractive index of 1.4 to 1.6.

Next, as shown in the top view of FIG. 14 and the sectional view of FIG. 15A, the photosensitive film 21 having the stripe-shaped openings 22 parallel to the vertical transfer register 7 is formed on the lens film 12.
Form on top. Here, the stripe-shaped openings 22 are respectively located on the photosensor rows. And in FIG.
As shown in the cross-sectional view of FIG.
The lens film 12 is etched by using the photosensitive film 21 having a mask. Here, the bottom position of the concave lens is, for example, the same as that of the above-described first embodiment. After that, as shown in the cross-sectional view of FIG. 15B, the photosensitive film 21 formed on the lens film 12 is removed. Here, FIG. 15A
15B is a sectional view taken along line BB in FIG.
FIG.

Next, as shown in the top view of FIG. 16 and the sectional view of FIG. 17, a photosensitive film 23 having openings 24 in a grid pattern is formed.
Are formed on the lens film 12. Here, each of the grid-shaped openings 24 is located on the photosensor 6. Then, as shown in the cross-sectional view of FIG. 17, the lens film 12 is etched using the photosensitive film 23 having the grid-shaped openings 24 as a mask. Here, the cross-sectional view of FIG. 17 is a cross-sectional view of the line segment CC in FIG. Then, the photosensitive film 23 formed on the lens film 12 is removed.

FIG. 18A is a sectional view taken along line CC in FIG. FIG. 18B is a sectional view taken along line DD in FIG. 16. 18A and 18B, the state where the photosensitive film 23 is removed is shown. As shown in FIGS. 18A and 18B, a concave lens having different heights in the vertical direction and the horizontal direction can be formed by the above-described etching.

The other points are the same as those in the above-described first embodiment, and the description thereof will be omitted.

Therefore, the fourth embodiment of the present invention has the following effects. Since the lens film 12 is etched a plurality of times by the photosensitive films having different mask patterns, it is possible to obtain a concave lens shape which cannot be obtained only by combining etching methods. That is, it is possible to obtain a concave lens shape that cannot be obtained in the first embodiment.

The embodiments of the present invention have been specifically described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made based on the technical idea of the present invention.

For example, the numerical values given in the above embodiments are merely examples, and different numerical values may be used if necessary.

Further, among the methods of manufacturing the solid-state image pickup device according to the first, second, third and fourth embodiments, at least two manufacturing methods may be combined.

Further, in the above-mentioned first embodiment,
When the isotropic etching is performed by dry etching, the gas conditions may be changed. For example, to alter the gas conditions containing a large amount of 0 _2. As a result, as shown in FIG. 19, the photosensitive film 17 formed on the lens film 12 can be retracted and the lens film 12 can be etched. Therefore, it is possible to form a concave lens having a shape that cannot be obtained in the first embodiment.

Further, in the above-mentioned first embodiment,
The etching may be anisotropic etching or isotropic etching. In this case, the type of etching is selected according to the shape of the concave lens 13 formed on the lens film 12.

Further, in the above-mentioned first embodiment,
The etching may be a combination of anisotropic etching and isotropic etching. In this case, the order of anisotropic etching and isotropic etching is determined according to the shape of the concave lens 13 formed on the lens film 12.

Further, in the first embodiment, the photosensitive film 1 is formed according to the shape of the concave lens 13 formed on the lens film 12.
The shape of the opening 18 included in 7, the etching time, and / or the material of the lens film 12 may be changed.

Further, in the above-mentioned first embodiment,
The etching may be a combination of wet etching and dry etching.

[0063]

As described above, according to the present invention, in the solid-state imaging device having the intralayer lens, the intralayer lens can be formed without being limited by the shape of the transfer electrode and the size of the unit cell. Therefore, a concave lens having a desired shape can be formed. Therefore, the light collection rate can be improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of a configuration of a solid-state image sensor according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an example of the configuration of the solid-state imaging device according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view showing an example of the method of manufacturing the solid-state imaging device according to the first embodiment of the present invention.

FIG. 4 is a top view showing an example of the shape of the photosensitive film according to the first embodiment of the present invention.

FIG. 5 is a cross-sectional view showing an example of the shape of a concave lens formed by anisotropic etching.

FIG. 6 is a sectional view showing an example of the shape of a concave lens formed by isotropic etching.

FIG. 7 is a cross-sectional view showing an example of the shape of a concave lens formed by etching in which anisotropic etching and isotropic etching are combined.

FIG. 8 is a cross-sectional view showing an example of the shape of a concave lens formed by etching in which anisotropic etching and isotropic etching are combined.

FIG. 9 is a sectional view showing an example of the configuration of a solid-state imaging device according to a second embodiment of the present invention.

FIG. 10 is a sectional view showing a first example of a lens film according to the second embodiment of the present invention.

FIG. 11 is a sectional view showing a second example of the lens film according to the second embodiment of the present invention.

FIG. 12 is a sectional view showing an example of the configuration of a solid-state imaging device according to a third embodiment of the present invention.

FIG. 13 is a sectional view showing an example of the configuration of a solid-state imaging device according to a third embodiment of the present invention.

FIG. 14 is a top view showing an example of an etching mask according to a fourth embodiment of the present invention.

FIG. 15 is a cross-sectional view illustrating the method for manufacturing the solid-state imaging device according to the fourth embodiment of the invention.

FIG. 16 is a top view showing an example of an etching mask according to a fourth embodiment of the present invention.

FIG. 17 is a cross-sectional view illustrating the method for manufacturing the solid-state imaging device according to the fourth embodiment of the present invention.

FIG. 18 is a transverse sectional view showing an example of the shape of a lens film according to the fourth embodiment of the present invention.

FIG. 19 is a cross-sectional view for explaining the modified example of the method for manufacturing the solid-state imaging device according to the first embodiment.

FIG. 20 is a cross-sectional view showing a configuration of a conventional solid-state image sensor.

[Explanation of symbols]

1 ... Solid-state image sensor, 2 ... Imaging area, 3 ... Horizontal transfer register, 4 ... Output part, 5 ... Peripheral area,
6 ... Photo sensor, 11 ... Shading curtain, 12 ...
Lens film, 13 ... concave lens, 14 ... flattening film,
15 ... Filter, 16 ... On-chip lens, 1
7, 21, 23 ... Photosensitive film, 18, 22, 24 ...
Aperture, 19, 20 ... High refractive index film

Claims (14)

[Claims] 1. A solid-state imaging device having an in-layer lens, wherein the in-layer lens is formed by applying an etching mask on a lens film and etching the lens film using the etching mask as a mask. A solid-state image sensor characterized by the above. 2. The solid-state image pickup device according to claim 1, wherein the etching is anisotropic etching or isotropic etching. 3. The solid-state image pickup device according to claim 1, wherein the etching is isotropic etching for retreating the etching mask and etching the lens film. 4. The solid-state imaging device according to claim 1, wherein the etching is a combination of anisotropic etching and isotropic etching. 5. The solid-state imaging device according to claim 1, wherein the lens film is composed of a plurality of films having different etching rates. 6. The solid-state imaging device according to claim 1, wherein a film made of a material having a refractive index higher than that of the material of the in-layer lens is formed on the in-layer lens formed by the etching. element. 7. A method of manufacturing a solid-state imaging device having an in-layer lens, the method comprising: forming an etching mask on a lens film; etching the lens film using the etching mask as a mask; And a step of removing the etching mask formed on the solid-state imaging device. 8. The method for manufacturing a solid-state image sensor according to claim 7, wherein the etching is anisotropic etching or isotropic etching. 9. The method for manufacturing a solid-state imaging device according to claim 7, wherein the etching is an isotropic etching in which the etching mask is set back and the lens film is etched. 10. The method for manufacturing a solid-state imaging device according to claim 7, wherein the etching is a combination of anisotropic etching and isotropic etching. 11. The method for manufacturing a solid-state image pickup device according to claim 7, wherein the lens film is composed of a plurality of films having different etching rates. 12. The method according to claim 7, further comprising the step of forming a film made of a material having a refractive index higher than that of the material of the intralayer lens on the intralayer lens formed by the etching. Of manufacturing the solid-state image sensor of. 13. A step of forming an etching mask having a mask pattern different from the etching mask on the lens film after the step of removing the etching mask, and an etching mask having a mask pattern different from the etching mask. 8. The method for manufacturing a solid-state imaging device according to claim 7, further comprising: a step of etching the lens film using the mask as a mask, and a step of removing an etching mask having a mask pattern different from the etching mask. 14. The solid-state imaging device according to claim 13, wherein the etching mask has stripe-shaped openings, and the etching mask having a mask pattern different from the etching mask has grid-shaped openings. Production method.