JP2009224361A - Solid state imaging apparatus and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid state imaging apparatus less liable to cause smear by oblique incident light, and to provide a method of manufacturing the same. <P>SOLUTION: A solid state imaging apparatus includes: a semiconductor substrate 101 in which a light-receiving section 102 performing photoelectric conversion is formed; a shading film 110 having an opening 109 in a region corresponding to the light-receiving section 102; a transparent insulating film 112 formed on the shading film 110 to fill the opening 109; and a color filter layer 113 formed on the transparent insulating film 112, wherein a concave lens 111 having a refractive index larger than that of the transparent insulating film 112 is formed in the opening 109. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device and a manufacturing method thereof, and more particularly to a technique for reducing smear.

  FIG. 11 is a cross-sectional view of a main part of a conventional solid-state imaging device. As shown in FIG. 11, a light receiving unit 602, a reading unit 603, a vertical transfer unit 604, and a channel stop unit 605 are formed on a silicon substrate 601 of a conventional solid-state imaging device by ion implantation of required impurities. . On the surface of the silicon substrate 601, a vertical transfer electrode 607 is formed in a region corresponding to the vertical transfer portion 604 via a silicon oxide film 606, and an opening 609 is provided in a region corresponding to the light receiving portion 602 thereon. A light shielding film 610 is formed, and an antireflection film 611 is formed inside the opening 609. A transparent insulating film 612 is formed on the light shielding film 610 and the antireflection film 611 so as to fill the opening 609, and a color filter layer 613 and a micro-on-chip lens 614 are formed thereon. In such a conventional solid-state imaging device, incident light is condensed on the light receiving unit 602 by the micro-on-chip lens 614 to improve sensitivity.

  In recent years, in the field of CCD (Charge Coupled Device) type solid-state imaging devices, with the widespread use of digital still cameras, digital video cameras, camera-equipped mobile phones, etc., miniaturization of devices and increase in pixels have been increasingly demanded. However, when the solid-state imaging device is downsized and the number of pixels is increased, the distance between the micro-on-chip lens 614 and the light receiving unit 602 is reduced, so that the focal position of incident light moves to the deep side of the silicon substrate 601. Further, since the opening 609 of the light shielding film 610 is reduced, the amount of light entering the light receiving portion 602 is reduced. As a result, the photoelectric conversion efficiency in the light receiving unit 602 decreases, the sensitivity of the solid-state imaging device decreases, and it becomes difficult to capture a clear image under a predetermined illuminance.

Therefore, in the solid-state imaging devices disclosed in Patent Documents 1 to 3, a convex inner lens (not shown) made of a high refractive index material is formed between the transparent insulating film 612 and the color filter layer 613, and the inner lens The incident light is further refracted to increase the amount of light entering the light receiving unit 602, thereby improving sensitivity.
Japanese Patent Laid-Open No. 11-40787 Japanese Patent Laid-Open No. 11-87672 JP 2002-353428 A

  However, when the light is condensed by the micro-on-chip lens 614 or the in-layer lens, oblique incident light as indicated by arrows in FIG. 11 increases. Such obliquely incident light is likely to leak into the vertical transfer unit 604 due to multiple reflection between the silicon substrate 601 and the antireflection film 611, the light shielding film 610, or the vertical transfer electrode 607, and thereby the vertical transfer unit 604. In this case, electric charge is generated by photoelectric conversion, and the generated electric charge behaves as a pseudo signal to generate noise called smear. Further, even when obliquely incident light is not subjected to photoelectric conversion by the light receiving unit 602 and is subjected to photoelectric conversion immediately below the vertical transfer unit 604, part of the charge generated immediately below enters the vertical transfer unit 604 and smear occurs. .

  Therefore, in the conventional solid-state imaging device, the opening 609 of the light shielding film 610 is reduced to increase the distance between the opening 609 and the vertical transfer unit 604, thereby reducing smear. However, if the opening 609 is reduced, the amount of light incident on the light receiving portion 602 is reduced, so that the sensitivity is lowered. That is, there is a trade-off between smear reduction and sensitivity improvement, and it is very difficult to satisfy both characteristics while reducing the size of the solid-state imaging device and increasing the number of pixels.

  In view of the above problems, an object of the present invention is to provide a solid-state imaging device in which smear due to obliquely incident light is unlikely to occur and a method for manufacturing the same.

In order to achieve the above object, a solid-state imaging device according to the present invention fills the opening with a semiconductor substrate on which a light receiving portion that performs photoelectric conversion is formed, a light shielding film having an opening in the region corresponding to the light receiving portion, and the opening. A solid-state imaging device comprising: a transparent insulating film formed on the light shielding film; and a color filter layer formed on the transparent insulating film,
A concave lens having a refractive index larger than that of the transparent insulating film is formed inside the opening.

  The method for manufacturing a solid-state imaging device according to the present invention includes a step of forming a light receiving portion that performs photoelectric conversion on a semiconductor substrate, a step of forming a light shielding film having an opening in the region corresponding to the light receiving portion, and an inside of the opening. A step of filling the transparent insulating member with a transparent insulating member, isotropic etching using a resist having a resist hole in a part of the region corresponding to the opening as a mask to make the upper surface of the transparent insulating member a concave curved surface, and removing the resist The method includes a step of depositing and planarizing a transparent insulating film, and a step of forming a color filter layer on the transparent insulating film.

  In the solid-state imaging device according to the present invention, since the concave lens having a refractive index larger than that of the transparent insulating film is formed inside the opening, the oblique incident light is changed to the normal incident light, or the incident angle close to the normal incident light is set. It can be made to enter into the light-receiving part 102 as the oblique incident light. Therefore, smear due to obliquely incident light hardly occurs.

  The method for manufacturing a solid-state imaging device according to the present invention includes a step of filling the inside of the opening of the light shielding film with a transparent insulating member, and isotropic etching using a resist having a resist hole in a part of the opening equivalent region as a mask. And a step of forming a concave curved surface on the upper surface of the transparent insulating member, a concave lens can be formed inside the opening. Therefore, it is possible to manufacture a solid-state imaging device in which smear due to obliquely incident light hardly occurs.

A solid-state imaging device and a manufacturing method thereof according to an embodiment of the present invention will be described with reference to the drawings.
[First Embodiment]
<Solid-state imaging device>
The solid-state imaging device according to the first embodiment includes a light receiving unit composed of a plurality of photodiodes formed in a matrix on a semiconductor substrate, and a vertical transfer unit that transfers signal charges read from each light receiving unit in the column direction. A CCD solid-state imaging device including a horizontal transfer unit that transfers signal charges transferred from a vertical transfer unit in a row direction.

  FIG. 1 is a cross-sectional view of a main part of the solid-state imaging device according to the first embodiment. As shown in FIG. 1, in the solid-state imaging device according to the first embodiment, a light receiving unit 102 that is a photodiode is formed on a silicon substrate 101 as a semiconductor substrate. On one side of the light receiving unit 102, a vertical transfer unit 104a that transfers signal charges read via the reading unit 103 is formed. On the other side of the light receiving unit 102, another adjacent light receiving unit (not shown) is formed. ) Is transferred, and a channel stop unit 105 is formed between the light receiving unit 102 and the vertical transfer unit 104b.

  On the surface of the silicon substrate 101, an insulating film 106 made of a silicon oxide film or the like, a vertical transfer electrode 107, an insulating film 108 made of a silicon oxide film or the like, and a light shielding film 110 having an opening 109 in a region corresponding to the light receiving portion 102. Are sequentially formed.

  The vertical transfer electrode 107 is formed in a region corresponding to the vertical transfer portions 104 a and 104 b, and an insulating film 108 is formed on the upper surface and side surfaces of the vertical transfer electrode 107. Since the light shielding film 110 covers the upper surface and side surfaces of the vertical transfer electrode 107, incident light does not directly enter the region other than the light receiving region of the light receiving unit 102. On the other hand, incident light directly enters the light receiving region of the light receiving unit 102 exposed through the opening 109.

  A concave lens 111 is formed inside the opening 109 of the light shielding film 110. On the light shielding film 110 and the concave lens 111, a flattened transparent insulating film 112 made of, for example, BPSG is formed so as to fill the opening 109. A color filter layer 113 is formed on the transparent insulating film 112, and a micro-on-chip lens 114 that collects incident light on the light receiving unit 102 is formed thereon.

  The concave lens 111 has a concave curved upper surface serving as an interface with the transparent insulating film 112 and a flat lower surface serving as an interface with the insulating film 106, and an outer peripheral surface thereof is in contact with an inner peripheral surface of the opening 109. The concave lens 111 is formed of, for example, a silicon nitride film, and its refractive index is smaller than that of the silicon substrate 101 but larger than that of the transparent insulating film 112. The lens curvature of the concave lens 111 is the same for all pixels.

  As indicated by an arrow in FIG. 1, the concave lens 111 has a characteristic of allowing oblique incident light generated by the micro-on-chip lens 114 and the like to enter the light receiving unit 102 as vertical incident light. Accordingly, obliquely incident light may be multiple-reflected between the silicon substrate 101 and the light shielding film 110 or between the silicon substrate 101 and the vertical transfer electrode 107 and leak into the vertical transfer portions 104a and 104b and directly below the vertical transfer portions 104a and 104b. Less smear due to obliquely incident light.

  Note that smear can be reduced most efficiently when the oblique incident light is made normal incident light and enters the light receiving unit 102. However, it is not always necessary to make the vertical incident light, and the incident angle of the oblique incident light is the incident angle of the vertical incident light. What is necessary is just to have the characteristic which approaches an angle (90 degrees). This is because the smear is reduced by the amount closer to the normal incident light.

  The outer peripheral surface of the concave lens 111 is preferably in contact with the inner peripheral surface of the opening 109. This is because all of the obliquely incident light entering the opening 109 can be converted into vertically incident light. However, the outer peripheral surface of the concave lens is not necessarily in contact with the inner peripheral surface of the opening, and the outer peripheral surface of the concave lens may be separated from the inner peripheral surface of the opening.

  The concave lens 111 preferably has a smaller refractive index than the silicon substrate 101. This is because the incident light is less likely to be reflected by the silicon substrate 101, and more incident light can enter the light receiving portion, so that the amount of incoming light increases.

  The entire concave lens 111 is preferably completely within the opening 109. If the obliquely incident light before entering the inside of the opening 109 is converted into the normal incident light by the concave lens 111, the vertical incident light may not enter the inside of the opening 109, and the amount of incoming light may be reduced. Because there is. However, the entire concave lens 111 does not necessarily need to be completely accommodated in the opening 109, and a part thereof may protrude from the opening 109. For example, the outer peripheral edge (thick part) of the concave lens 111 may protrude from the opening 109.

<Manufacturing method>
A method for manufacturing the solid-state imaging device according to the first embodiment will be described below. First, as shown in FIG. 1, a p-type impurity is implanted into a predetermined position of the silicon substrate 101, and a reading portion 103 and a channel stop portion 105 are formed at predetermined intervals. Next, an n-type impurity is implanted to form the light receiving unit 102 between the readout unit 103 and the channel stop unit 105, and the vertical transfer units 104a and 104b are formed outside the readout unit 103 and the channel stop unit 105, respectively. To do.

  Next, after an insulating film 106 such as a silicon oxide film and a polysilicon film (not shown) are sequentially formed on the surface of the silicon substrate 101 by a thermal oxidation method or a CVD method, the insulating film 106 and the polysilicon film are formed by known lithography. Patterning is performed by a technique and an etching technique. Then, after forming the vertical transfer electrode 107 in the region corresponding to the vertical transfer portions 104a and 104b, a silicon oxide film 108 is formed on the surface of the vertical transfer electrode 107 by a thermal oxidation method or the like.

  Next, after depositing a metal film such as aluminum and tungsten by sputtering, CVD, or the like, patterning is performed by a known lithography technique and etching technique to cover the vertical transfer electrode 107 and to form an opening 109 in a region corresponding to the light receiving portion 102. A light-shielding film 110 having is formed.

  Next, the concave lens 111 is formed. FIG. 2 is a diagram for explaining an example of a method for forming a concave lens according to the first embodiment. First, a silicon nitride film, for example, is deposited on the light shielding film 110 so as to fill the opening 109 by a known CVD method or sputtering method, and further the silicon nitride film is deposited by a known CMP method or resist etchback method. The surface is flattened to the same height as 110, and the inside of the opening 109 is filled with the transparent insulating member 111a (FIG. 2A).

  At this time, in the CMP and resist etch back processing, if the metal used for the light shielding film 110 is detected, the processing time can be controlled, and the silicon nitride film is flattened to the same height as the light shielding film 110. It is easy to convert. Of course, it is possible to form a similar structure by CMP and resist etchback with a fixed processing time.

  Next, the transparent insulating member 111a is isotropically etched by known dry etching or wet etching using the resist 116 having the resist hole 115 in a part of the region corresponding to the opening 109 as a mask, and the upper surface of the transparent insulating member 111a is recessed. A curved surface is formed (FIG. 2B).

  At this time, if the size of the resist hole 115 of the resist 116 (for example, the opening area of the resist hole 115) is controlled without changing the isotropic etching conditions, it is easy to form the concave curved surface with the desired curvature. . Of course, it is possible to form a concave curved surface having an optimal curvature even if the etching conditions are changed. In the etching process, if the metal used for the light shielding film 110 is detected, the processing time can be controlled more easily, and the thickness (height) of the concave lens 111 can be easily controlled. Of course, it is possible to form a similar structure by etching with a fixed processing time.

  Finally, if the resist 116 is removed, the concave lens 111 is completed (FIG. 2C). After that, as shown in FIG. 1, a transparent insulating film 112 is formed on the light shielding film 110 and the concave lens 111 so as to fill the step, and a color filter layer 113 and a micro-on-chip lens 114 are sequentially formed.

According to the above manufacturing method, it is easy to form the concave lens 111 having the optimum curvature and thickness inside the opening 109 of the light shielding film 110.
[Modification 1]
<Solid-state imaging device>
In the solid-state imaging device according to the first embodiment, the lens curvature of the concave lens 111 is the same in all pixels. However, in the solid-state imaging device according to Modification 1, the lens curvature of the concave lens is different for each color of the color filter layer. Different. Hereinafter, the solid-state imaging device according to Modification 1 will be described by taking as an example the case where primary color filters (red, green, blue) are used.

  FIG. 3 is a cross-sectional view of a main part of the solid-state imaging device according to the first modification. As shown in FIG. 3, the solid-state imaging device according to Modification 1 includes a red color filter layer 213a, a green color filter layer 213b, and a blue color filter layer 213c, and corresponding to these color filter layers 213a to 213c, a concave lens The lens curvatures 211a to 211c are optimized for each color.

  The lens curvature (curvature of the upper surface) is the largest for the concave lens 211a for red, the second largest for the concave lens 211b for green, and the smallest for the concave lens 211c for blue. It should be noted that the thicknesses (heights) of the central portions of the concave lenses 211a to 211c are all the same.

  As described above, with respect to the obliquely incident light split by the color filter layers 213a to 213c, the red concave lens 211a having a large lens curvature is used for the long wavelength red light, and the lens curvature is small for the short wavelength blue light. By using the blue concave lens 211c, the oblique incident light of each color is made to be the optimum vertical incident light and enters the silicon substrate 101, and smear is reduced.

  This configuration can also be applied to complementary color filters (yellow, magenta, cyan, green), etc. If the lens curvature of the concave lens is changed by the length of the wavelength of the split incident light (the longer the wavelength, the more the lens curvature becomes). Smear can be effectively reduced by increasing it).

  As described above, in the solid-state imaging device according to the first modification, the lens curvature of the concave lens is different for each color of the color filter layer. Therefore, the lens curvature can be optimized according to the wavelength of incident light. By optimizing as described above, several kinds of obliquely incident light separated into specific wavelengths by the color filter layers 213a to 213c can be made to enter the light receiving section as optimum perpendicular incident light respectively.

<Manufacturing method>
A method for manufacturing the solid-state imaging device according to Modification 1 will be described below. Since the method is substantially the same as that of the first embodiment except for the method of forming a concave lens, the method of forming a concave lens will be mainly described.

  First, a silicon nitride film, for example, is deposited on the light shielding film so as to fill the opening by a known CVD method or sputtering method, and further, the silicon nitride film is deposited on the light shielding film by a known CMP method or resist etch back method. And flattening the inside of the opening with a transparent insulating member.

  FIG. 4 is a diagram for explaining an example of a method for forming a concave lens according to the first modification. Next, as shown in FIG. 4, the transparent insulating member is isotropically etched by known dry etching or wet etching using the resist 216 having resist holes 215a to 215c in a part of the region corresponding to the opening as a mask. The concave lenses 211a to 211c are formed by making the upper surface of the member a concave curved surface.

  The resist holes 215a to 215c of the resist 216 have different sizes for each color of the color filter layer, the red resist hole 215c is the smallest, the green resist hole 215b is the next smallest, and the blue resist hole 215a is the largest. According to this formation method, the concave lenses 211a to 211c having the lens curvature optimized for each color of the color filter layers 213a to 213c can be easily formed at a time.

[Modification 2]
<Solid-state imaging device>
In the solid-state imaging device according to the first embodiment, the lens thickness of the concave lens 111 is the same for all pixels. However, in the solid-state imaging device according to Modification Example 2, the lens thickness of the concave lens is different for each color of the color filter layer. Different. Hereinafter, the solid-state imaging device according to the modification 2 will be described by taking as an example a case where primary color filters (red, green, blue) are used.

  In general, when light enters a high refractive index material from a low refractive index material, reflection occurs at the interface, and the reflection is between those of a low refractive index material and a high refractive index material. It can be suppressed by inserting a material having a refractive index between them, and the optimum thickness of the material to be inserted is known to vary depending on the wavelength of light entering. That is, as shown in FIG. 1, when the incident light enters the silicon substrate 101 having a high refractive index from the transparent insulating film 112 having a low refractive index as in the solid-state imaging device according to the first embodiment, If the refractive index is the refractive index between the transparent insulating film 112 and the silicon substrate 101, the concave lens 111 exhibits an antireflection effect, the reflection by the silicon substrate 101 is suppressed, and the incident light effectively enters the light receiving unit 102. Enter and improve sensitivity.

  FIG. 5 is a cross-sectional view of a main part of the solid-state imaging device according to the second modification. As shown in FIG. 5, the solid-state imaging device according to the second modification includes a red color filter layer 313a, a green color filter layer 313b, and a blue color filter layer 313c, and a concave lens corresponding to these color filter layers 313a to 313c. The lens thicknesses 311a to 311c are optimized for each color.

  Regarding the lens thickness (lens height), the concave lens 311a for red is the thickest (high), the concave lens 311b for green is the next thickest, and the concave lens 311c for blue is the thinnest (low). More specifically, the red color is the thickest, the green color is the next thickest, and the blue color is the thinnest at both the lens center and the lens outer peripheral edge. The concave lens 311a to 311c have the same lens curvature (curvature of the upper surface).

  As described above, with respect to the oblique incident light split by the color filter layers 313a to 313c, the red concave lens 311a having a large lens thickness is used for the long wavelength red light, and the lens thickness is thin for the short wavelength blue light. By using the blue concave lens 311c, the oblique incident light of each color is made the optimum vertical incident light and enters the silicon substrate 101 to reduce smear.

  In the second modification, the thickness of the central portion of the lens is 155 to 170 nm for the red color filter layer 313a, 130 to 145 nm for the green color filter layer 313b, and 105 to 120 nm for the blue color filter layer 313c. Optimum sensitivity was obtained.

  This configuration can also be applied to complementary color filters (yellow, magenta, cyan, green), etc. If the lens thickness of the concave lens is changed depending on the wavelength of the split incident light (the longer the wavelength, the thicker the lens thickness) The smear can be effectively reduced.

  As described above, in the solid-state imaging device according to the modified example 2, since the lens thickness of the concave lens is different for each color of the color filter layer, the lens thickness can be optimized according to the wavelength of incident light. By optimizing as described above, several kinds of obliquely incident light separated into specific wavelengths by the color filter layers 313a to 313c can be made to enter the light receiving section as optimum vertical incident light respectively.

<Manufacturing method>
A method for manufacturing the solid-state imaging device according to Modification 2 will be described below. Since the method is substantially the same as that of the first embodiment except for the method of forming a concave lens, the method of forming a concave lens will be mainly described.

  First, a silicon nitride film, for example, is deposited on the light shielding film so as to fill the opening by a known CVD method or sputtering method, and further, the silicon nitride film is deposited on the light shielding film by a known CMP method or resist etch back method. And flattening the inside of the opening with a transparent insulating member.

  FIG. 6 is a diagram for explaining an example of a method of forming a concave lens according to the second modification. Next, as shown in FIG. 6, for each color, a transparent insulating member is used as a known dry material with resists 316a to 316c having resist holes 315a to 315c in a part of the region corresponding to the opening of the target color as a mask. Concave lenses 311a to 311c are formed by isotropic etching by etching or wet etching, and making the upper surface of the transparent insulating member a concave curved surface. The resists 316a to 316c are formed and removed for each color. At this time, if the etching time is controlled, the concave lenses 311a to 311c having a target lens thickness can be easily formed.

[Modification 3]
12A and 12B are diagrams showing a conventional solid-state imaging device, in which FIG. 12A is a schematic plan view showing an imaging region, FIG. 12B is a cross-sectional view of the main part of the central portion of the imaging region, and FIG. FIG.

  In the conventional solid-state imaging device, since the incident light is a vertical component light in the pixel in the center of the imaging region as indicated by symbol b in FIG. 12A, as shown in FIG. The lens 714a is disposed immediately above the light receiving portion 702a. On the other hand, since the incident light is an oblique component light in the pixels in the periphery of the imaging region as indicated by reference character c in FIG. 12A, the micro-on-chip lens 714b is a light receiving portion as shown in FIG. It is arranged to be shifted with respect to 702b.

  As described above, by shifting the micro-on-chip lens 714b in the pixels in the periphery of the imaging region, incident light is more focused on the light receiving unit 702b, thereby improving the sensitivity. However, since the oblique incident light is increased as compared with the central portion of the imaging region, smear having a low level is generated. The solid-state imaging device according to the modified example 3 has a configuration that suppresses such poor smear.

<Solid-state imaging device>
7A and 7B are diagrams illustrating a solid-state imaging device according to Modification Example 3, in which FIG. 7A is a schematic plan view illustrating an imaging region, FIG. It is principal part sectional drawing of an area | region periphery part.

  In the solid-state imaging device according to Modification 3, in the pixel in the center of the imaging region as indicated by reference numeral b in FIG. 7A, as shown in FIG. 7B, the micro-on-chip lens 414a includes the light receiving unit 402a. The lens center portion of the concave lens 411 a coincides with the center portion of the opening 409 a of the light shielding film 410. On the other hand, in the pixel in the periphery of the imaging region as indicated by reference character c in FIG. 7A, as shown in FIG. 7C, the micro-on-chip lens 414b moves toward the center of the imaging region with respect to the light receiving unit 402b. The concave lens 411b is formed so as to be shifted from the center of the opening 409b of the light shielding film 410 to the outside of the imaging region.

  In this way, in the pixels in the periphery of the imaging region, the micro-on-chip lens 414b that is shifted by shifting the lens central portion of the concave lens 411b to the outside of the imaging region with respect to the central portion of the opening 409b of the light shielding film 410. The obliquely incident light collected through the light can enter the light receiving unit 402b as normal incident light. As a result, smear can be reduced even in the periphery of the imaging region. In addition, it is easy to optimize the lens shape in the periphery of the imaging region.

<Manufacturing method>
A method for manufacturing the solid-state imaging device according to Modification 3 will be described below. Since the method is substantially the same as that of the first embodiment except for the method of forming a concave lens, the method of forming a concave lens will be mainly described.

  First, a silicon nitride film, for example, is deposited on the light shielding film so as to fill the opening by a known CVD method or sputtering method, and further, the silicon nitride film is deposited on the light shielding film by a known CMP method or resist etch back method. And flattening the inside of the opening with a transparent insulating member.

  8A and 8B are diagrams for explaining an example of a method for forming a concave lens according to the modification 3. FIG. 8A is a diagram for explaining a method for forming a concave lens of a pixel in the center of the imaging region, and FIG. These are the figures for demonstrating the formation method of the concave lens of the pixel of an imaging region center part. As shown in FIG. 8A, the position of the resist hole 415a coincides with the center of the opening 409a of the light shielding film 410 in the center of the imaging region, and in the periphery of the imaging region as shown in FIG. 8B. The resist film 415b is isotropically etched by known dry etching or wet etching using the resist 416 whose resist hole 415b is shifted to the outside of the imaging region with respect to the center of the opening 409b of the light shielding film 410 as a mask. Form a curved surface.

  If this formation method is used, the objective concave lenses 411a and 411b can be formed by optimizing the positions of the resist holes 415a and 415b in all the pixels in the imaging region, and smear can be effectively reduced. it can.

[Second Embodiment]
The solid-state imaging device according to the second embodiment is basically the same as the solid-state imaging device 2 of the first embodiment, except that the connection mode between the terminal pad and the conductive pad on the translucent protective plate is different. Has a configuration. Therefore, common components are denoted by the same reference numerals as those in the first embodiment, and the description thereof will be omitted or simplified, and the above connection mode will be mainly described.

<Solid-state imaging device>
FIG. 9 is a cross-sectional view of a main part of the solid-state imaging device according to the second embodiment. As shown in FIG. 9, the solid-state imaging device according to the second embodiment includes a silicon substrate 501, a light receiving unit 502, a reading unit 503, vertical transfer units 504a and 504b, a channel stop unit 505, an insulating film 506, and a vertical transfer electrode. The configurations of 507, insulating film 508, opening 509, and light shielding film 510 are substantially the same as those of the solid-state imaging device according to the first embodiment. Therefore, the description about these is abbreviate | omitted.

  A concave lens 511 is formed inside the opening 509 of the light shielding film 510, and a flattened transparent insulating film 512 made of, for example, BPSG is formed on the light shielding film 510 and the concave lens 511. Further, on the transparent insulating film 512, for example, a hydrogen supply film 517 containing hydrogen formed from a silicon nitride film or a silicon oxynitride film and a color filter layer 513 are sequentially formed, and the color filter layer 513 is formed. A micro-on-chip lens 514 for condensing incident light onto the light receiving unit 502 is formed on the substrate.

  The concave lens 511 is formed of, for example, a silicon nitride film, and has a light guide hole 518 penetrating toward the light receiving portion 502 at the center of the lens, and the outer peripheral surface thereof is in contact with the inner peripheral surface of the opening 509 of the light shielding film 510. The refractive index is smaller than that of the silicon substrate 501 but larger than that of the transparent insulating film 512.

  In the solid-state imaging device according to the second embodiment, a concave lens 511 having a refractive index smaller than that of the silicon substrate 501 and larger than that of the transparent insulating film 512 is formed in the opening 509 of the light shielding film 510 on the light receiving portion 502. Therefore, the oblique incident light generated by the condensing by the micro-on-chip lens 514 becomes vertical incident light by the concave lens 511 and enters the light receiving unit 502. Therefore, it is possible to effectively reduce smear caused by obliquely incident light without reducing sensitivity.

  The obliquely incident light rarely passes through the center of the lens, and even if it passes through the center of the lens, there is a distance to the vertical transfer units 504a and 504b. Therefore, even if the light guide hole 518 is formed in the central portion of the concave lens 511, the incident light rarely enters the vertical transfer units 504a and 504b due to multiple reflection, and the incident light enters the light receiving unit 502.

  In a conventional solid-state imaging device, charges are thermally excited at the interface state due to dangling bonds between silicon on the silicon substrate surface and silicon at the silicon oxide film interface, and the charges act as noise called dark current, resulting in degradation of imaging characteristics. There is a problem of doing. Therefore, hydrogen annealing treatment or heat treatment after forming a silicon nitride film containing hydrogen is performed to diffuse hydrogen into the silicon substrate, and dangling bonds are terminated with hydrogen to reduce dark current.

  In the solid-state imaging device according to the second embodiment, the hydrogen supply film 517 is deposited and then hydrogen annealing is performed. The hydrogen released from the hydrogen supply film 517 passes through the light guide hole 518 of the concave lens 511 and the silicon substrate 501. To spread. As a result, the dark current is effectively reduced.

  The concave lens 511 made of a silicon nitride film itself also contains hydrogen, which contributes to the termination of dangling bonds by supplying hydrogen, and the dark current is also reduced by the concave lens 511. This effect also exists in the concave lens 111 of the solid-state imaging device according to the first embodiment.

  The solid-state imaging device according to the second embodiment supplies hydrogen from the hydrogen supply film 517 to the silicon substrate 501 through the light guide hole 518 of the concave lens 511 in addition to the effects exhibited by the solid-state imaging device according to the first embodiment. can do. Therefore, dangling bonds can be hydrogen-terminated and dark current can be effectively reduced.

<Manufacturing method>
A method for manufacturing the solid-state imaging device according to the second embodiment will be described below. Since the steps until the light shielding film 510 is formed are substantially the same as those of the solid-state imaging device according to the first embodiment, the subsequent steps will be described.

  FIG. 10 is a diagram for explaining an example of a concave lens forming method according to the second embodiment. First, the inside of the opening 509 of the light shielding film 510 is filled with a transparent insulating member, and the upper surface of the transparent insulating member is formed into a concave curved surface. Thereafter, as shown in FIG. 10, the transparent insulating member having a concave curved upper surface is anisotropically etched by known dry etching using a resist 516 having a resist hole 515 in a region corresponding to the central portion of the lens of the transparent insulating member as a mask. Then, the light guide hole 518 is formed in the transparent insulating member. Finally, the resist 516 is removed, and the concave lens 511 is completed.

  Thereafter, as shown in FIG. 9, a transparent insulating film 512 is formed on the light shielding film 510 and the concave lens 511 so as to fill the step, and a hydrogen supply film 517 is further formed. Thereafter, annealing is performed in an atmosphere containing hydrogen, hydrogen is released, and dangling bonds on the surface of the silicon substrate 501 are terminated. In the second embodiment, dark current was most reduced when annealing was performed at a temperature of 400 to 500 ° C. for 30 to 60 minutes. Thereafter, the color filter layer 513 and the micro-on-chip lens 514 are sequentially formed.

[Musubi]
The solid-state imaging device and the manufacturing method thereof according to the present invention have been specifically described above based on the embodiments. However, the solid-state imaging device and the manufacturing method thereof according to the present invention are not limited to the above-described embodiments.

  For example, the solid-state imaging device according to the present invention has a configuration in which a part of the configuration of the solid-state imaging device according to the first and second embodiments and the first to third modifications of the first embodiment is combined. Also good. Each of them can be used in combination, and by combining them, there may be a case where synergistic reduction of smear and reduction of dark current can be obtained.

  The solid-state imaging device and the manufacturing method thereof according to the present invention can realize a solid-state imaging device capable of effectively reducing smear by allowing oblique incident light to enter the light receiving unit as vertical incident light by a concave lens, and in particular, a solid-state imaging device including a concave lens. It is useful as an imaging device and a manufacturing method thereof.

Sectional drawing of the principal part of the solid-state imaging device which concerns on 1st Embodiment The figure for demonstrating an example of the formation method of the concave lens which concerns on 1st Embodiment. Sectional drawing of the principal part of the solid-state imaging device concerning the modification 1 The figure for demonstrating an example of the formation method of the concave lens which concerns on the modification 1. Sectional drawing of the principal part of the solid-state imaging device concerning the modification 2 The figure for demonstrating an example of the formation method of the concave lens which concerns on the modification 2. It is a figure which shows the solid-state imaging device which concerns on the modification 3, Comprising: (a) is a schematic plan view which shows an imaging area, (b) is principal part sectional drawing of an imaging area center part, (c) is an imaging area periphery part. Cross section of the main part It is a figure for demonstrating an example of the formation method of the concave lens which concerns on the modification 3, Comprising: (a) is a figure for demonstrating the formation method of the concave lens of the pixel of an imaging region center part, (b) is an imaging region center. For explaining the method of forming the concave lens of the pixels of the part Sectional drawing of the principal part of the solid-state imaging device concerning 2nd Embodiment The figure for demonstrating an example of the formation method of the concave lens which concerns on 2nd Embodiment. Sectional view of the main part of a conventional solid-state imaging device It is a figure which shows the conventional solid-state imaging device, (a) is a schematic plan view which shows an imaging area, (b) is principal part sectional drawing of an imaging area center part, (c) is principal part sectional drawing of an imaging area periphery part Figure

Explanation of symbols

101, 501 Semiconductor substrates 102, 402a, 402b, 502 Light receiving portions 104a, 104b, 504a, 504b Vertical transfer portions 109, 409a, 409b, 509 Openings 110, 410, 510 Light shielding films 111, 211a to 211c, 311a to 311c, 411a, 411b, 511 Concave lens 111a Transparent insulating member 112, 512 Transparent insulating film 113, 213a-213c, 313a-313c, 513 Color filter layer 115, 215a-215c, 315a-315c, 415a, 415b, 515 Resist hole 116, 216 , 316a to 316c, 416, 516 Resist 518 Light guide hole

Claims (12)

A semiconductor substrate on which a light receiving portion for performing photoelectric conversion is formed; a light shielding film having an opening in the region corresponding to the light receiving portion; a transparent insulating film formed on the light shielding film so as to fill the opening; and the transparent A solid-state imaging device comprising a color filter layer formed on an insulating film,
A solid-state imaging device, wherein a concave lens having a refractive index larger than that of the transparent insulating film is formed inside the opening.   The solid-state imaging device according to claim 1, wherein the concave lens has a characteristic of making oblique incident light enter the light receiving unit as vertical incident light.   The solid-state imaging device according to claim 1, wherein an outer peripheral surface of the concave lens is in contact with an inner peripheral surface of the opening.   The solid-state imaging device according to claim 1, wherein the concave lens has a lens curvature different for each color of the color filter layer.   5. The solid-state imaging device according to claim 1, wherein the concave lens has a lens thickness different for each color of the color filter layer.   The solid-state imaging device according to claim 1, wherein the concave lens has a refractive index smaller than that of the semiconductor substrate.   The solid-state imaging device according to claim 1, wherein the concave lens is formed of a silicon nitride film.   8. The solid-state imaging device according to claim 1, wherein the concave lens has a light guide hole that penetrates toward the light receiving portion at a center portion of the lens.   A plurality of the light receiving portions are formed in a matrix on the semiconductor substrate, and a vertical transfer portion that transfers the signal charges read from the light receiving portions in the column direction, and a signal charge transferred from the vertical transfer portions. The solid-state imaging device according to claim 1, further comprising a horizontal transfer unit configured to transfer in a direction, and functioning as a CCD type solid-state imaging device.   Forming a light receiving portion for performing photoelectric conversion on a semiconductor substrate, forming a light shielding film having an opening in the region corresponding to the light receiving portion, filling the inside of the opening with a transparent insulating member, and the opening A step of isotropically etching using a resist having a resist hole in a part of a corresponding region as a mask to make the upper surface of the transparent insulating member a concave curved surface; a step of removing the resist and depositing and planarizing a transparent insulating film; And a step of forming a color filter layer on the transparent insulating film.   The method of manufacturing a solid-state imaging device according to claim 10, wherein the resist hole has a different size for each color of the color filter layer.   After the step of making the upper surface of the transparent insulating member a concave curved surface, before the step of depositing and planarizing the transparent insulating film, anisotropic etching is performed using a resist having a resist hole in a part of the region corresponding to the opening as a mask. The method for manufacturing a solid-state imaging device according to claim 10, further comprising a step of providing a light guide hole in the transparent insulating member.

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