阅读说明：本技术 摄像元件和摄像元件的制造方法 (Image pickup element and method for manufacturing image pickup element ) 是由 柴山利一 守屋雄介 光永将幸 于 2019-01-21 设计创作，主要内容包括：本发明减少在摄像元件中入射光的反射,其中,透明树脂被布置在微透镜的表面上。根据本发明的摄像元件设置有像素、微透镜、透明树脂层和密封玻璃。像素被形成在半导体基板上,并且产生与照射在像素上的光对应的图像信号。微透镜与像素相邻布置,并且在使像素的表面平坦化的同时将入射光聚焦在像素上。透明树脂层与微透镜相邻布置,并且被构造为具有与微透镜的折射率相差预定值的折射率。密封玻璃与透明树脂相邻布置,并且密封半导体基板。(The present invention reduces reflection of incident light in an image pickup element in which a transparent resin is arranged on the surface of a microlens. An image pickup element according to the present invention is provided with pixels, microlenses, a transparent resin layer, and a sealing glass. The pixels are formed on a semiconductor substrate, and generate image signals corresponding to light irradiated on the pixels. The microlens is disposed adjacent to the pixel, and focuses incident light on the pixel while planarizing a surface of the pixel. The transparent resin layer is disposed adjacent to the microlenses and is configured to have a refractive index different from a refractive index of the microlenses by a predetermined value. The sealing glass is disposed adjacent to the transparent resin, and seals the semiconductor substrate.)

1. An image pickup element, comprising:

a pixel formed on the semiconductor substrate and configured to generate an image signal from the irradiation light;

a microlens arranged adjacent to the pixel and configured to collect incident light, irradiate the pixel with the incident light, and planarize a surface of the pixel;

a transparent resin layer disposed adjacent to the microlenses and having a refractive index different from that of the microlenses by a predetermined difference; and

a sealing glass disposed adjacent to the transparent resin and sealing the semiconductor substrate.

2. The image pickup element according to claim 1, wherein the transparent resin layer has the refractive index such that the predetermined difference is 0.4 to 0.6.

3. The image pickup element according to claim 1, wherein the transparent resin layer includes a first transparent resin layer which is disposed adjacent to the microlens and has a refractive index different from the refractive index of the microlens by the predetermined difference, and a second transparent resin layer which has a refractive index different from that of the first transparent resin layer.

4. The image pickup element according to claim 3, wherein the transparent resin layer includes an antireflection layer between the first transparent resin layer and the second transparent resin layer.

5. The image pickup element according to claim 1, wherein the microlens is formed using an organic material.

6. The image pickup element according to claim 1, wherein the microlens includes a lens portion formed using an inorganic material, and a planarized portion having substantially the same refractive index as the lens portion and disposed adjacent to the pixel.

7. The image pickup element according to claim 1, wherein the microlens includes an antireflection film.

8. The image pickup element according to claim 7, wherein the microlens includes a region as an uneven surface of the microlens, the region serving as the antireflection film.

9. The image pickup element according to claim 1, further comprising:

an image pickup lens disposed adjacent to a surface of the sealing glass, the surface being different from a surface of the sealing glass on which the transparent resin layer is disposed.

10. A method of manufacturing an image pickup element, the method comprising:

a pixel forming step of forming pixels on a semiconductor substrate, the pixels being configured to generate image signals from irradiation light;

a microlens arranging step of arranging microlenses adjacent to the formed pixel, the microlenses collecting incident light to irradiate the pixel with the incident light, and planarizing a surface of the pixel;

a transparent resin layer arranging step of arranging a transparent resin layer adjacent to the arranged microlenses, a refractive index of the transparent resin layer differing from a refractive index of the microlenses by a predetermined difference; and

a sealing step of disposing a sealing glass adjacent to the disposed transparent resin layer, the sealing glass sealing the semiconductor substrate.

Technical Field

The present invention relates to an imaging element and a method of manufacturing the imaging element. In particular, the present invention relates to an image pickup element including a microlens and a method of manufacturing the image pickup element.

Background

Conventionally, the following image pickup elements have been used: which has a semiconductor chip for performing image pickup and is housed in a hollow package having a glass window. In order to improve reliability, the hollow package is formed using ceramic or the like. Pixels for converting the irradiation light into an electric signal are arranged in the image pickup element in a two-dimensional lattice manner. Microlenses are arranged in each of the plurality of pixels, and the microlenses collect incident light. In the hollow package described above, the air inside the package and the microlens are in contact with each other. Since the refractive index of air is relatively small, the refractive index difference between air and the microlens can be increased, and incident light can be refracted to a large extent on the surface of the microlens. Therefore, the efficiency of the microlens in collecting incident light can be improved.

In contrast, an image pickup element having a simplified configuration has been proposed in which a sealing glass is adhered to a light receiving surface of a semiconductor chip via a transparent resin. In the case of this image pickup element, the microlens is in contact with the transparent resin. Since the transparent resin has a higher refractive index than air, by using silicon nitride (SiN) having a larger refractive index as a microlens material, a refractive index difference on the surface of the microlens can be secured, and a decrease in light collection efficiency can be reduced. For example, the following solid-state imaging elements have been proposed: which has a light-transmitting insulating layer, a first planarizing layer, a color filter, a second planarizing layer, a stress relaxing layer, a microlens containing SiN, and a transparent resin layer laminated in this order on a semiconductor substrate including a photoelectric conversion unit (for example, see patent document 1). In the solid-state imaging element, the second planarizing layer is formed using an organic material, and thus the stress relaxing layer is disposed between the second planarizing layer and the microlens formed using an inorganic material. The stress relaxation layer has an interlayer stress between the second planarization film and the microlens, and relaxes a stress difference between the second planarization film and the microlens.

Reference list

Patent document

Patent document 1: japanese patent application laid-open No. 2014-168098

Disclosure of Invention

Problems to be solved by the invention

In the above-described conventional technique, since a plurality of layers having different refractive indices are arranged between the microlens and the color filter, there is a problem that incident light is reflected at an interface between the layers. Since the reflected incident light is reflected again at the interface between the seal glass and the air (outside air) and enters the pixel, there is a problem that the image quality deteriorates.

The present invention has been made in view of the above problems, and an object of the present invention is to reduce reflection of incident light in an image pickup element having a transparent resin disposed on a surface of a microlens.

Technical scheme for solving problems

The present invention is directed to solving the above-described problems, and a first aspect of the present invention is an image pickup element including: a pixel formed on the semiconductor substrate and configured to generate an image signal from the irradiation light; a microlens arranged adjacent to the pixel and configured to collect incident light, irradiate the pixel with the incident light, and planarize a surface of the pixel; a transparent resin layer disposed adjacent to the microlenses and having a refractive index different from that of the microlenses by a predetermined difference; and a sealing glass which is disposed adjacent to the transparent resin and seals the semiconductor substrate.

Further, in the first aspect, the transparent resin layer may have the refractive index such that the predetermined difference is 0.4 to 0.6.

Further, in the first aspect, the transparent resin layer may include a first transparent resin layer disposed adjacent to the microlens and having a refractive index different from the refractive index of the microlens by the predetermined difference, and a second transparent resin layer having a refractive index different from the first transparent resin layer.

Further, in the first aspect, the transparent resin layer may include an antireflection layer between the first transparent resin layer and the second transparent resin layer.

Further, in the first aspect, the microlens may be formed using an organic material.

Further, in the first aspect, the microlens may include a lens section formed using an inorganic material, and a planarized section having substantially the same refractive index as the lens section and disposed adjacent to the pixel.

Further, in the first aspect, the microlens may include an antireflection film.

Further, in the first aspect, the microlens includes a region serving as a concave-convex surface of the microlens, the region serving as the antireflection film.

Further, in the first aspect, an image pickup lens disposed adjacent to a surface of the sealing glass, which is different from the surface of the sealing glass on which the transparent resin layer is disposed, may be further included.

Further, a second aspect of the present technology is a method of manufacturing an image pickup element, the method including: a pixel forming step of forming pixels on a semiconductor substrate, the pixels being configured to generate image signals from irradiation light; a microlens arranging step of arranging microlenses adjacent to the formed pixel, the microlenses collecting incident light to irradiate the pixel with the incident light, and planarizing a surface of the pixel; a transparent resin layer arranging step of arranging a transparent resin layer adjacent to the arranged microlenses, a refractive index of the transparent resin layer differing from a refractive index of the microlenses by a predetermined difference; and a sealing step of disposing a sealing glass adjacent to the disposed transparent resin layer, the sealing glass sealing the semiconductor substrate.

This aspect brings about the following effects: the surface of the pixel is planarized by the microlens while using the microlens having a refractive index different from that of the transparent resin layer by a predetermined difference. The film for planarizing the surface of the pixel may be omitted, and in an image pickup element having a transparent resin layer and a sealing glass arranged adjacent to a microlens arranged in the pixel, it is assumed that reflection of incident light at the pixel surface is reduced.

Effects of the invention

According to the present invention, an excellent effect of reducing reflection of incident light is exhibited in an image pickup element having a transparent resin arranged on a surface of a microlens.

Drawings

Fig. 1 is a diagram illustrating a configuration example of an image pickup element according to an embodiment of the present invention.

Fig. 2 is a diagram illustrating a configuration example of a pixel according to an embodiment of the present invention.

Fig. 3 is a cross-sectional view illustrating a configuration example of an image pickup element according to an embodiment of the present invention.

Fig. 4 is a cross-sectional view illustrating a configuration example of a pixel according to the first embodiment of the present invention.

Fig. 5 is a diagram illustrating an example of a method of manufacturing an image pickup element according to the first embodiment of the present invention.

Fig. 6 is a diagram illustrating an example of a method of manufacturing an image pickup element according to the first embodiment of the present invention.

Fig. 7 is a diagram illustrating an example of a method of manufacturing an image pickup element according to the first embodiment of the present invention.

Fig. 8 is a cross-sectional view illustrating a configuration example of a pixel according to a second embodiment of the present invention.

Fig. 9 is a cross-sectional view illustrating a configuration example of a pixel according to a third embodiment of the present invention.

Fig. 10 is a cross-sectional view illustrating a configuration example of a pixel according to a fourth embodiment of the present invention.

Fig. 11 is a diagram illustrating a configuration example of an antireflection film according to a fourth embodiment of the present invention.

Fig. 12 is a cross-sectional view illustrating a configuration example of a pixel according to a fifth embodiment of the present invention.

Fig. 13 is a block diagram illustrating a schematic configuration example of a camera as an example of an image pickup apparatus to which the present technology is applied.

Detailed Description

Next, embodiments (hereinafter, referred to as embodiments) for implementing the present invention will be described with reference to the drawings. In the following drawings, the same or similar parts are denoted by the same or similar reference numerals. It is to be noted that the drawings are schematic, and the size ratio of the respective portions and the like do not always correspond to an actual size ratio. Further, it is needless to say that the dimensional relationship and the ratio are different between the drawings. Further, the embodiments will be described in the following order.

1. First embodiment

2. Second embodiment

3. Third embodiment

4. Fourth embodiment

5. Fifth embodiment

6. Application example of Camera

<1. first embodiment >

[ Structure of image pickup element ]

Fig. 1 is a diagram illustrating a configuration example of an image pickup element according to an embodiment of the present invention. The image pickup element 1 in fig. 1 includes a pixel array unit 10, a vertical driving unit 201, a column signal processing unit 202, and a control unit 203.

The pixel array unit 10 has pixels 100 arranged in a two-dimensional lattice. Here, the pixel 100 generates an image signal corresponding to the irradiation light. The pixel 100 includes a photoelectric conversion unit that generates charges according to irradiation light. In addition, the pixel 100 includes a pixel circuit. The pixel circuit generates an image signal based on the electric charges generated by the photoelectric conversion unit. The generation of the image signal is controlled by a control signal generated by the vertical driving unit 201 described below. In the pixel array unit 10, the signal lines 109 and 108 are arranged in an XY matrix. The signal line 109 is a signal line for transmitting a control signal of a pixel circuit in the pixel 100, is arranged for each row of the pixel array unit 10, and is wired in common to the pixels 100 arranged in each row. The signal line 108 is a signal line for transmitting an image signal generated by a pixel circuit of the pixel 100, is arranged for each column of the pixel array unit 10, and is commonly wired to the pixels 100 arranged in each column. The photoelectric conversion unit and the pixel circuit are formed on a semiconductor substrate.

The vertical driving unit 201 generates a control signal of the pixel circuit of the pixel 100. The vertical driving unit 201 transmits the generated control signal to the pixel 100 via the signal line 109 in fig. 1. The column signal processing unit 202 processes the image signal generated by the pixel 100. The column signal processing unit 202 processes an image signal transmitted from the pixel 100 via the signal line 108 in fig. 1. The processing in the column signal processing unit 202 corresponds to, for example, analog-to-digital conversion for converting an analog image signal generated in the pixel 100 into a digital image signal. The image signal processed by the column signal processing unit 202 is output as an image signal of the image pickup element 1. The control unit 203 controls the entire image pickup element 1. The control unit 203 controls the image pickup element 1 by generating and outputting a control signal for controlling the vertical driving unit 201 and the column signal processing unit 202. The control signal generated by the control unit 203 is transmitted to each of the vertical driving unit 201 and the column signal processing unit 202 via signal lines 209 and 208.

The vertical driving unit 201, the column signal processing unit 202, and the control unit 203 described above are formed on a semiconductor chip different from the pixel array unit 10. Specifically, the vertical driving unit 201, the column signal processing unit 202, and the control unit 203 are formed on the signal processing chip 20. As described below, the signal processing chip 20 is bonded and laminated on the semiconductor chip constituting the pixel array unit 10 to form one semiconductor package.

[ Circuit configuration of pixels ]

Fig. 2 is a diagram illustrating a configuration example of a pixel according to an embodiment of the present invention. Fig. 2 is a circuit diagram illustrating a configuration example of the pixel 100. The pixel 100 in fig. 2 includes a photoelectric conversion unit 101, a charge holding unit 102, and MOS transistors 103 to 106.

The anode of the photoelectric conversion unit 101 is grounded, and the cathode of the photoelectric conversion unit 101 is connected to the source of the MOS transistor 103. The drain of the MOS transistor 103 is connected to the source of the MOS transistor 104, the gate of the MOS transistor 105, and one end of the charge holding unit 102. The other end of the charge holding unit 102 is grounded. The drains of the MOS transistors 104 and 105 are commonly connected to the power supply line Vdd, and the source of the MOS transistor 105 is connected to the drain of the MOS transistor 106. A source of the MOS transistor 106 is connected to the signal line 108. The gates of the MOS transistors 103, 104, and 106 are connected to a transmission signal line TR, a reset signal line RST, and a selection signal line SEL, respectively. Note that the transfer signal line TR, the reset signal line RST, and the selection signal line SEL constitute the signal line 109.

As described above, the photoelectric conversion unit 101 generates charges according to the irradiation light. A photodiode may be used for the photoelectric conversion unit 101. Further, the charge holding unit 102 and the MOS transistors 103 to 106 constitute a pixel circuit.

The MOS transistor 103 is a transistor that transfers the charge generated by photoelectric conversion by the photoelectric conversion unit 101 to the charge holding unit 102. The charge transfer in the MOS transistor 103 is controlled by a signal transferred through the transfer signal line TR. The charge holding unit 102 is a capacitor that holds the charge transferred by the MOS transistor 103. The MOS transistor 105 is a transistor that generates a signal based on the electric charge held in the electric charge holding unit 102. The MOS transistor 106 is a transistor that outputs a signal generated by the MOS transistor 105 to the signal line 108 as an image signal. The MOS transistor 106 is controlled by a signal transmitted by a selection signal line SEL.

The MOS transistor 104 is a transistor that resets the charge holding unit 102 by discharging the charge held in the charge holding unit 102 to the power supply line Vdd. The reset by the MOS transistor 104 is controlled by a signal transmitted through the reset signal line RST and is performed before the charge transmission by the MOS transistor 103. Note that at the time of this reset, the photoelectric conversion unit 101 can be further reset by making the MOS transistor 103 conductive. In this way, the pixel circuit converts the electric charges generated by the photoelectric conversion unit 101 into an image signal.

[ Cross-sectional Structure of image pickup element ]

Fig. 3 is a cross-sectional view illustrating a configuration example of an image pickup element according to an embodiment of the present invention. Fig. 3 is a cross-sectional view illustrating the configuration of the image pickup element 1. The image pickup element 1 in fig. 3 includes a pixel array unit 10, a signal processing chip 20, and an image pickup lens 181.

The pixel array unit 10 in fig. 3 includes a semiconductor substrate 12, a wiring region 13, a transparent resin layer 161, and a sealing glass 171.

The semiconductor substrate 12 is a semiconductor substrate in which semiconductor region portions among elements of the pixels 100 arranged in the pixel array unit 10 are formed. The semiconductor substrate 12 may be formed using silicon.

The wiring region 13 is a region where wirings for connecting elements of the pixel 100 and wirings constituting the signal line 109 and the like are formed. The wiring region 13 has inter-chip connection pads 134 arranged therein. The inter-chip connection pads 134 are the following electrodes: which is connected to an inter-chip connection pad 234 disposed in the signal processing chip 20 described below, and exchanges signals and the like. The inter-chip connection pad 134 may be formed using a metal, for example, copper (Cu).

The rear surface of the semiconductor substrate 12, which is a surface different from the front surface where the wiring region 13 is arranged, is formed with the microlenses 151. The microlens 151 is a lens that collects incident light and irradiates the incident light onto the pixels 100 arranged in the pixel array unit 10. An image pickup element of a type that picks up an image of incident light irradiated on the rear surface of the semiconductor substrate 12 is referred to as a back-illuminated image pickup element.

The sealing glass 171 is glass that seals the imaging element 1 and protects the imaging element 1. As the sealing glass 171, for example, glass having a refractive index of 1.5 can be used.

The transparent resin layer 161 is a transparent resin disposed between the semiconductor substrate 12 and the sealing glass 171. The transparent resin layer 161 is a resin that is arranged adjacent to the microlenses 151 on the rear surface of the semiconductor substrate 12 and adheres the sealing glass 171 to the semiconductor substrate 12. Further, the refractive index of the transparent resin layer 161 is different from that of the microlens 151 by a predetermined difference. Further, by setting the refractive index of the transparent resin layer 161 to 1.5, which is the same as that of the sealing glass 171, reflection of incident light at the interface between the sealing glass 171 and the transparent resin layer 161 can be reduced. Details of the configurations of transparent resin layer 161 and microlenses 151 will be described below.

The signal processing chip 20 includes a semiconductor substrate 22, a wiring region 23, a through electrode 243, a back-surface-side pad 242, a resin layer 241, and a solder ball 244.

The semiconductor substrate 12 is a semiconductor substrate formed using silicon or the like, and semiconductor region portions among elements constituting the vertical driving unit 201, the column signal processing unit 202, and the control unit 203 included in the signal processing chip 20 are formed in the semiconductor substrate 22.

The wiring region 23 is a region where wirings and the like for connecting elements included in the signal processing chip 20 are formed. An inter-chip connection pad 234 connected to the inter-chip connection pad 134 of the pixel array unit 10 is arranged in the wiring region 23. Further, the front-surface-side pad 235 is arranged in the wiring region 23. Front-surface-side pad 235 is an electrode connected to back-surface-side pad 242 via a through-electrode 243 described below.

The back-surface-side pads 242 are arranged on the back surface of the semiconductor substrate 22. The back-surface-side pads 242 are electrodes for connection with an external circuit such as an image processing apparatus connected to the image pickup element 1. Through-electrodes 243 are arranged between front-surface-side pads 235 and back-surface-side pads 242, and electrically connect front-surface-side pads 235 and back-surface-side pads 242. The back-surface-side pad 242 and the through-electrode 243 may be formed using a metal (e.g., Cu).

The solder balls 244 are hemispherical solders arranged adjacent to the back-surface-side pads 242. The solder balls 244 are solder for mounting the image pickup element 1 on a substrate of an external circuit. The resin layer 241 is a resin for protecting the signal processing chip 20 and the back-surface-side pads 242. For the resin layer 241, for example, a solder resist may be used.

The wiring region 13 of the pixel array unit 10 and the wiring region 23 of the signal processing chip 20 are bonded so that the pixel array unit 10 and the signal processing chip 20 are stacked. At this time, the inter-chip connection pads 134 and 234 are adjacently bonded. Specifically, the pixel array unit 10 and the signal processing chip 20 are brought into contact with each other by aligning the inter-chip connection pads 134 and 234 in a manner adjacent to each other, and the pixel array unit 10 and the signal processing chip 20 are heated and pressure-bonded. As a result, the wiring regions 13 and 23 are connected, and the inter-chip connection pads 134 and 234 are mechanically and electrically connected. As a result, signal transmission between the pixel array unit 10 and the signal processing chip 20 becomes possible. Such connections between semiconductor chips are referred to as Cu-Cu connections. The signal lines 108 and 109 shown in fig. 1 include this Cu-Cu connection.

The imaging lens 181 is called a wafer level lens, and is an imaging lens integrally formed with the imaging element 1.

Note that the configuration of the image pickup element 1 is not limited to this example. For example, instead of the solder balls 244, a configuration in which pads for solder connection are arranged in an island shape with respect to the resin layer 241 may be adopted. Further, the image pickup element 1 without the image pickup lens 181 may be employed.

[ Structure of pixel ]

Fig. 4 is a cross-sectional view illustrating a configuration example of a pixel according to the first embodiment of the present invention. Fig. 4 is a cross-sectional view illustrating a region of the pixel array unit 10 where the pixels 100 are formed.

The pixel 100 in fig. 4 includes a semiconductor substrate 12, a wiring region 13, an insulating film 123, a light-shielding film 142, a color filter 141, and a microlens 151.

In the semiconductor substrate 12, for example, a p-type well region 121 is formed, and a semiconductor region constituting an element of the pixel 100 is formed in the well region 121. For convenience, it is assumed that the semiconductor substrate 12 in fig. 4 is formed using the well region 121. In fig. 4, the photoelectric conversion unit 101 shown in fig. 2 is illustrated as an example of an element constituting the pixel 100. The semiconductor region 122 in fig. 4 is an n-type semiconductor region. The photoelectric conversion unit 101 is formed using a semiconductor region 122 and a well region surrounding the semiconductor region 122. The photodiode is formed by a pn junction at the interface between the n-type semiconductor region 122 and the p-type well region.

The wiring region 13 has disposed therein an insulating layer 131, a wiring layer 132, and a via plug 133. The wiring layer 132 is a wiring for transmitting signals. The elements constituting the pixel 100 are wired through the wiring layer 132. The wiring layer 132 may be formed using a metal such as Cu.

The insulating layer insulates the wiring layer 132. For example, the insulating layer 131 may be formed using a material such as silicon oxide (SiO)₂) Etc. of insulating material. The wiring layer 132 and the insulating layer 131 may be formed in multiple layers. Fig. 4 illustrates an example of the wiring layer 132 and the insulating layer 131 formed as three layers. The via plugs 133 connect the wiring layers 132 formed in different layers. The via plug 133 may be formed using, for example, Cu or tungsten (W).

The wiring layer 132 is connected to an inter-chip connection pad 134 arranged on the surface of the wiring region 13 via a via plug 133. As described above, the wiring layer 132, the via plug 133, and the inter-chip connection pad 134 constitute the signal line 109 and the like in the pixel array unit 10.

The insulating film 123 is a film for insulating the semiconductor substrate 12. The insulating film 123 may be made of, for example, SiO₂And (4) forming.

The color filter 141 is a filter that transmits light having a predetermined wavelength among light entering the pixel 100. As the color filter 141, a color filter that transmits any one of red light, green light, and blue light may be arranged. The color filter 141 may be formed using an organic material, such as a resin in which a pigment or a dye is dispersed. At this time, the color filter 141 has different thicknesses and different refractive indexes according to the wavelength of the transmitted light. The refractive index of the color filter 141 is, for example, 1.6 to 1.8.

The light shielding film 142 is disposed between the pixels 100 and shields incident light. The light shielding film 142 shields light obliquely incident from the adjacent pixel 100. With the light blocking film 142, incidence of light transmitted through the color filters 141 corresponding to different colors of the adjacent pixels 100 can be prevented, and occurrence of color mixing can be prevented.

The microlens 151 is a hemispherical lens that collects incident light on the photoelectric conversion unit 101 of the pixel 100. The microlens 151 is arranged for each pixel 100, and is arranged adjacent to the pixel 100. In fig. 4, the microlens 151 is disposed adjacent to the color filter 141 in the pixel 100. In addition, the microlens 151 planarizes the surface of the pixel 100. In fig. 4, the microlens 151 planarizes the surface of the color filter 141. As described above, the color filters 141 are formed to have different thicknesses according to the corresponding colors. The microlenses 151 in fig. 4 are formed in a hemispherical shape while planarizing the surface of the color filter 141. As a result, the height of the microlens 151 can be made uniform between the adjacent pixels 100. In addition, the microlens 151 in fig. 4 may be formed using an organic material, and may be a lens having a refractive index of 2.0. Specifically, titanium oxide (TiO) dispersed therein as a filler may be used₂) The microlenses 151 are formed of the acrylic resin.

The transparent resin layer 161 is disposed adjacent to the microlenses 151 and has a refractive index different from that of the microlenses 151. Thereby, incident light may be refracted at an interface between the transparent resin layer 161 and the microlens 151. The transparent resin layer 161 may be formed using, for example, an acrylic resin or an epoxy resin. For example, the refractive index can be set to 1.5 using these resins.

The larger the refractive index difference between the transparent resin layer 161 and the microlenses 151 is, the more the incident light transmitted through the microlenses 151 can be refracted, and the focal length can be further shortened. For example, 0.4 to 0.6 may be employed as the refractive index difference, and the pixel 100 may be formed according to the focal length based on the refractive index difference. In the above example of the microlens 151 and the transparent resin layer 161, the refractive index difference is 0.5. By employing the simplified packaging as described above, it is possible to collect incident light in the image pickup element 1 having a configuration in which an air layer is not arranged on the surface of the microlens 151. A transparent resin layer 161 having a large refractive index may be disposed instead of air having a refractive index of 1.0.

Further, the microlenses 151 formed using an organic material are formed while planarizing the surface of the color filter 141. Therefore, the planarization film between the color filter 141 and the microlens 151 may be omitted. Further, since the color filter 141 and the microlens 151 are formed using resin, the thermal expansion coefficients of the color filter 141 and the microlens 151 are relatively close to each other. Therefore, the occurrence of stress due to the difference in the thermal expansion coefficients is reduced, and the arrangement of the film for relaxing the stress can be omitted.

In the case where a planarizing film or the like is disposed between the color filter 141 and the microlens 151, the following phenomenon occurs: incident light reflected by a planarization film or the like is reflected again at the surface of the sealing glass 171 in contact with air and enters the pixel 100. This may cause, for example, a so-called annular spot in which concentric light is reflected around the image pickup light source, resulting in deterioration of image quality. Since the image pickup element 1 in fig. 4 does not need a planarization film or the like, the film configuration of the pixel 100 can be simplified, and reflection of incident light can be reduced. The image quality can be prevented from being deteriorated.

[ method for manufacturing image pickup element ]

Fig. 5 to 7 are diagrams illustrating an example of a method of manufacturing an image pickup element according to a first embodiment of the present invention. Fig. 5 to 7 are diagrams illustrating an example of manufacturing steps of the image pickup element 1. First, the well region 121, the semiconductor region 122, and the like are formed on the semiconductor wafer 301 constituting the semiconductor substrate 12. Next, the wiring region 13 is formed on the surface of the semiconductor substrate 12 (a in fig. 5).

Next, the semiconductor wafer 301 constituting the semiconductor substrate 12 is inverted and bonded to the semiconductor wafer 302 constituting the semiconductor substrate 22 formed with the wiring region 23. At this time, a Cu-Cu connection is formed between the inter-chip connection pads 134 and 234. Next, the surface of the semiconductor wafer 301 constituting the semiconductor substrate 12 is polished to reduce the thickness (b in fig. 5).

Next, the insulating film 123, the light-shielding film 142, and the color filter 141 are sequentially stacked on the surface of the semiconductor substrate 12 (c in fig. 5). The pixel 100 may be formed on the semiconductor substrate 12 through the steps shown in a to c in fig. 5.

Next, a resin layer 401 serving as a material of the microlens 151 is coated on the surface of the color filter 141, and a resist 402 is disposed on the surface of the resin layer 401. The resist 402 is formed in a hemispherical shape similar to the microlens 151. For example, a resist material is coated, exposed, and developed to form an island-shaped resist. Thereafter, the resist is heated to a temperature equal to or higher than the softening temperature of the resist using a reflow furnace or the like, and is formed into a hemispherical shape (d in fig. 6).

Next, the resin layer 401 is etched using the resist 402 as a mask. Dry etching may be used as the etching. Thereby, the shape of the resist 402 is transferred to the resin layer 401, and the microlens 151 can be formed. This method of manufacturing the microlens 151 is called an etch-back method (e in fig. 6). Through this process, the microlens 151 may be disposed adjacent to the color filter 141 of the pixel 100.

Next, a transparent resin layer 161 is applied onto the surface of the microlens 151 (f in fig. 7). Thereby, the transparent resin layer 161 may be disposed adjacent to the microlenses 151. Next, sealing glass 171 is disposed on the surface of coated transparent resin layer 161, and transparent resin layer 161 is cured (g in fig. 7). Thereby, the sealing glass 171 may be disposed adjacent to the transparent resin layer 161, and the semiconductor substrate 12 may be sealed with the sealing glass 171.

Next, the through-electrodes 243 and the back-surface-side pads 242 are formed in the semiconductor substrate 22, and the resin layer 241 is applied. The coated resin layer 241 is etched to form an opening adjacent to the back-surface-side pad 242, and a solder ball 244 is formed in the opening. Next, the imaging lens 181 is placed on the surface of the sealing glass 171 and cut into individual pieces. The image pickup element 1 can be manufactured by the above-described steps.

Note that the method of manufacturing the image pickup element 1 is not limited to this example. For example, in forming the microlenses 151, a material resin of the microlenses 151 may be applied onto the surface of the color filter 141 by spin coating or the like to planarize the surface of the color filter 141. Thereafter, a material resin of the microlens 151 may be thickly coated to form the resin layer 401.

As described above, with the image pickup element 1 according to the first embodiment of the present invention, the microlens 151 that is formed of an organic material and has a refractive index different from that of the transparent resin layer 161 by a predetermined difference is used. As a result, reflection of incident light in the image pickup element having the transparent resin arranged on the surface of the microlens can be reduced.

<2 > second embodiment

The image pickup element 1 of the first embodiment described above uses the microlens 151 formed of an organic material. In contrast, the image pickup element 1 according to the second embodiment of the present invention is different from the above-described first embodiment in that a microlens formed of an inorganic material is used.

[ Structure of pixel ]

Fig. 8 is a cross-sectional view illustrating a configuration example of a pixel according to a second embodiment of the present invention. The image pickup element 1 in fig. 8 is different from the image pickup element 1 described with reference to fig. 4 in that a microlens 156 is included instead of the microlens 151.

The microlens 156 includes a lens portion 152 and a planarization portion 153. The lens portion 152 is a lens formed using an inorganic material. As a material constituting the lens portion 152, for example, an oxide having a refractive index of 2.0 or more can be used. By using the lens section 152, the difference in refractive index from the transparent resin layer 161 can be set to 0.5 or more.

The planarization part 153 is disposed adjacent to the surface of the pixel 100 to planarize the surface of the pixel 100. In fig. 8, the planarization portion 153 planarizes the surface of the color filter 141. A transparent resin may be used for the planarization portion 153. Further, by setting the refractive index of the flattening portion 153 to a value substantially the same as the refractive index of the lens portion 152, reflection of incident light at the interface between the lens portion 152 and the flattening portion 153 can be reduced.

Further, in the case where the film stress of the planarization portion 153 is set to a value between the respective film stresses of the lens portion 152 and the color filter 141, the film stresses of the lens portion 152 and the color filter 141 can be relaxed.

Descriptions of configurations of the image pickup element 1 other than the above-described configuration are omitted because these configurations are similar to those of the image pickup element 1 described in the first embodiment of the present invention.

As described above, the image pickup element 1 according to the second embodiment of the present invention has the flattening portion 153 arranged between the lens portion 152 and the color filter 141, thereby reducing reflection of incident light in the case of using the lens portion 152 formed of an inorganic material.

<3. third embodiment >

The image pickup element 1 of the above embodiment uses the single transparent resin layer 161. In contrast, the image pickup element 1 according to the third embodiment of the present invention is different from the above-described first embodiment in that a transparent resin layer including a plurality of layers is used.

[ Structure of pixel ]

Fig. 9 is a cross-sectional view illustrating a configuration example of a pixel according to a third embodiment of the present invention. The image pickup element 1 in fig. 9 is different from the image pickup element 1 described with reference to fig. 4 in that a microlens 154 is included instead of the microlens 151, and a transparent resin layer 162 and an antireflection layer 163 are further included.

The microlens 154 is a lens having a refractive index having a value smaller than that of the microlens 151, and for example, the microlens 154 has a refractive index having a value of 1.9. For example, the microlenses 154 may be formed using an organic material such as a resin or the like. Since a resin having a high refractive index is not used, the microlenses can be formed relatively easily, similar to the microlenses 151.

The transparent resin layer 162 is a transparent resin layer that is disposed adjacent to the microlenses 154 and has a refractive index different from that of the microlenses 154 by a predetermined difference. Further, the transparent resin layer 161 is a transparent resin layer having a refractive index different from that of the transparent resin layer 162. The refractive index of the transparent resin layer 161 may be set to, for example, 1.5, which is the same as the refractive index of the sealing glass 171.

When the microlens 154 having a refractive index of 1.9 is used and a value of 0.5 is used as the refractive index difference with the transparent resin layer, it is necessary to use the transparent resin layer having a refractive index of 1.4 or less. However, in the case where the transparent resin layer having a refractive index of 1.4 or less is disposed, the refractive index is different from that of the sealing glass 171. Therefore, reflection of incident light occurs at the interface between the transparent resin layer and the sealing glass 171. Therefore, the transparent resin layer 161 having the same refractive index as the sealing glass 171 is used as a transparent resin layer adjacent to the sealing glass 171, and the transparent resin layer 162 having a refractive index of 1.4 or less is further disposed. Thereby, the above-described predetermined difference, which is the refractive index difference between the transparent resin layer and the microlenses 154, can be ensured while preventing reflection of incident light between the transparent resin layer and the sealing glass 171. Note that the transparent resin layer 162 is an example of the first transparent resin layer described in claims. The transparent resin layer 161 is an example of the second transparent resin layer described in claims.

The anti-reflection layer 163 is disposed between the transparent resin layers 161 and 162, and reduces reflection of incident light at an interface between the anti-reflection layer 163 and each of the transparent resin layers 161 and 162. The anti-reflection layer 163 is formed to have a thickness of 1/4 of the wavelength of the incident light so that the phase of the reflected light from the interface between the anti-reflection layer 163 and the transparent resin layer 162 is reversed with respect to the reflected light from the interface between the anti-reflection layer 163 and the transparent resin layer 161. Thereby, the reflected light from the interface between each of the transparent resin layers 161 and 162 and the antireflection layer 163 is cancelled out, and the reflection is reduced. For example, SiO can be used₂SiN and SiON form such an anti-reflection layer 163. By further including the anti-reflection layer 163, reflection of incident light at the interface between the anti-reflection layer 163 and each of the transparent resin layers 161 and 162 can be reduced. Note that the anti-reflection layer 163 may be omitted.

Descriptions of configurations of the image pickup element 1 other than the above-described configuration are omitted because these configurations are similar to those of the image pickup element 1 described in the first embodiment of the present invention.

As described above, the image pickup element 1 according to the third embodiment of the present invention has the transparent resin layers 161 and 162 having different refractive indices. Thereby, it is possible to arrange a transparent resin layer having a refractive index different by a predetermined difference from the microlens 154 while preventing reflection between the transparent resin layer and the sealing glass 171, and it is possible to reduce reflection of incident light even in the case of using the microlens 154 having a relatively small refractive index.

<4. fourth embodiment >

The image pickup element 1 of the third embodiment described above uses the antireflection layer 163. In contrast, the image pickup element 1 according to the fourth embodiment of the present invention is different from the above-described third embodiment in that a microlens including an antireflection film is used.

[ Structure of pixel ]

Fig. 10 is a cross-sectional view illustrating a configuration example of a pixel according to a fourth embodiment of the present invention. The image pickup device 1 in fig. 10 is different from the image pickup device 1 described with reference to fig. 9 in that an antireflection film 155 is further included on the surface of the microlens 154.

The antireflection film 155 is a film formed on the surface of the microlens 154, and reduces reflection of incident light at the interface between the microlens 154 and the transparent resin layer 162. By disposing the antireflection film 155, reflection of incident light in the image pickup element 1 can be further reduced.

[ Structure of antireflection film ]

Fig. 11 is a diagram illustrating a configuration example of an antireflection film according to a fourth embodiment of the present invention. The antireflection film 155 in fig. 11 has irregularities formed on the surface of the microlens 154. Such irregularities scatter reflected light and inhibit light from being incident on the pixel 100 again. Such an antireflection film 155 can be formed by, for example, selectively etching a metal contained in the microlens 154. Note that the size of the uneven portion of the antireflection film 155 is favorably 150nm or less. This is because the influence of diffraction on the adjacent pixels 100 can be reduced. Note that the configuration of the antireflection film 155 is not limited to this example. For example, an antireflection film 155 having a similar configuration to the antireflection layer 163 may be used.

Descriptions of configurations of the image pickup element 1 other than the above-described configuration are omitted because these configurations are similar to those of the image pickup element 1 described in the third embodiment of the present invention.

As described above, the image pickup element 1 according to the fourth embodiment of the present invention uses the microlens 154 including the antireflection film 155, thereby further suppressing reflection of incident light.

<5. fifth embodiment >

The imaging element 1 of the second embodiment uses the lens section 152 formed of an inorganic material having a refractive index of 2.0 or more. In contrast, the image pickup element 1 according to the fifth embodiment of the present invention is different from the above-described second embodiment in that a lens section formed of an inorganic material having a relatively small refractive index is used.

[ Structure of pixel ]

Fig. 12 is a cross-sectional view illustrating a configuration example of a pixel according to a fifth embodiment of the present invention. The image pickup element 1 in fig. 12 is different from the image pickup element 1 described with reference to fig. 8 in that a microlens 159 is used instead of the microlens 156, and a transparent resin layer 162 and an antireflection layer 163 described with reference to fig. 9 are further included.

The microlens 159 in fig. 12 includes a lens portion 157 and a flattening portion 158. The lens portion 157 is formed using an inorganic material, and the refractive index is set to, for example, 1.9. Further, the flattening portion 158 in fig. 12 has substantially the same refractive index as the lens portion 157. Descriptions of other configurations of the lens portion 157 and the flattening portion 158 are omitted because they are similar to those of the lens portion 152 and the flattening portion 153 described with reference to fig. 8.

In the image pickup element 1 of fig. 12, even in the case of using the lens section 157 formed of an inorganic material having a refractive index of 1.9, the surface of the color filter 141 can be planarized by the planarization section 158, and the refractive index difference between the lens section 157 and the transparent resin layer 162 can be set to 0.5. That is, effects similar to the case of using the microlens 151 formed of an organic material having a refractive index of 2.0 described with reference to fig. 4 can be obtained. Further, by disposing the anti-reflection layer 163, reflection of incident light at the interface between the anti-reflection layer 163 and each of the transparent resin layers 161 and 162 can be reduced.

Descriptions of configurations of the image pickup element 1 other than the above-described configuration are omitted because these configurations are similar to those of the image pickup element 1 described in the third embodiment of the present invention.

As described above, in the image pickup element 1 according to the fifth embodiment of the present invention, the transparent resin layer 162 and the antireflection layer 163 are arranged. Thus, in the case of using the lens section 157 formed of an inorganic material, reflection at the interface between the anti-reflection layer 163 and each of the transparent resin layers 161 and 162 can be reduced while ensuring that the refractive index difference between the transparent resin layer 162 and the lens section 157 is 0.5.

<6. application of Camera >

The present techniques may be applied to a variety of products. For example, the present technology can be implemented as an image pickup element mounted on an image pickup apparatus such as a camera.

Fig. 13 is a block diagram illustrating a schematic configuration example of a camera as an example of an image pickup apparatus to which the present technology is applied. The camera 1000 in fig. 13 includes a lens 1001, an image pickup element 1002, an image pickup control unit 1003, a lens driving unit 1004, an image processing unit 1005, an operation input unit 1006, a frame memory 1007, a display unit 1008, and a recording unit 1009.

The lens 1001 is an imaging lens of the camera 1000. The lens 1001 collects light from an object, and causes the collected light to enter an image pickup element 1002 described below to form an image of the object.

The image pickup element 1002 is a semiconductor element, and picks up light from an object collected by the lens 1001. The image pickup element 1002 generates an analog image signal from the irradiation light, converts the analog image signal into a digital image signal, and outputs the digital image signal.

An image pickup control unit 1003 controls image pickup by the image pickup element 1002. The image pickup control unit 1003 controls the image pickup element 1002 by generating a control signal and outputting the control signal to the image pickup element 1002. Further, the image pickup control unit 1003 can perform auto focusing in the camera 1000 based on an image signal output from the image pickup element 1002. Here, the auto focus is a system that detects a focus position of the lens 1001 and automatically adjusts the focus position. As the auto-focusing, the following method may be used: the image plane phase difference is detected by using phase difference pixels arranged in the image pickup element 1002, and the focus position is detected, thereby detecting the image plane phase difference (image plane phase difference autofocus). Further, a method of detecting a position where the contrast of an image is highest as a focus position (contrast autofocus) may also be applied. The image capture control unit 1003 adjusts the position of the lens 1001 via the lens driving unit 1004 based on the detected focus position, and performs auto-focusing. Note that the image pickup control unit 1003 may be formed using, for example, a Digital Signal Processor (DSP) equipped with firmware.

A lens driving unit 1004 drives the lens 1001 based on the control of the imaging control unit 1003. The lens driving unit 1004 may change the position of the lens 1001 by using an internal motor, thereby driving the lens 1001.

An image processing unit 1005 processes an image signal generated by the image pickup element 1002. This processing corresponds to, for example, demosaicing for generating an image signal of a missing color in image signals corresponding to red, green, and blue of each pixel, noise reduction for removing noise of the image signal, encoding of the image signal, and the like. The image processing unit 1005 may be formed using, for example, a microcomputer equipped with firmware.

The operation input unit 1006 receives an operation input from a user of the camera 1000. As the operation input unit 1006, for example, a button or a touch panel can be used. The operation input received by the operation input unit 1006 is transmitted to the image capturing control unit 1003 and the image processing unit 1005. Thereafter, processing corresponding to the operation input, for example, processing such as image capturing of the object is started.

The frame memory 1007 is a memory for storing frames, which are image signals of one picture. The frame memory 1007 is controlled by the image processing unit 1005, and holds frames during image processing.

The display unit 1008 displays the image processed by the image processing unit 1005. For the display unit 1008, for example, a liquid crystal panel can be used.

The recording unit 1009 records the image processed by the image processing unit 1005. For the recording unit 1009, for example, a memory card or a hard disk can be used.

A camera to which the present invention is applicable has been described. The present technology can be applied to the image pickup element 1002 in the above-described configuration. Specifically, the image pickup element 1 described with reference to fig. 1 can be applied to the image pickup element 1002. By applying the image pickup element 1 to the image pickup element 1002, reflection of incident light can be reduced in an image pickup element employing a package having a simple configuration. Degradation of the image quality of the image generated by the camera 1000 can be prevented.

It is to be noted that although a camera is described here as an example, the technique according to the present invention can be applied to, for example, a monitoring apparatus or the like.

Finally, the description of the above embodiments is an example of the present invention, and the present invention is not limited to the above embodiments. Therefore, it is needless to say that various modifications other than the above-described embodiments may be made in accordance with design or the like as long as the modifications do not depart from the technical idea according to the present invention.

Note that the present invention may also have the following configuration.

(1) An image pickup element, comprising:

a pixel formed on the semiconductor substrate and configured to generate an image signal from the irradiation light;

a microlens arranged adjacent to the pixel and configured to collect incident light, irradiate the pixel with the incident light, and planarize a surface of the pixel;

a transparent resin layer disposed adjacent to the microlenses and having a refractive index different from that of the microlenses by a predetermined difference; and

a sealing glass disposed adjacent to the transparent resin and sealing the semiconductor substrate.

(2) The image pickup element according to (1), wherein the transparent resin layer has the refractive index such that the predetermined difference is 0.4 to 0.6.

(3) The image pickup element according to (1) or (2), wherein the transparent resin layer includes a first transparent resin layer which is arranged adjacent to the microlens and has a refractive index different from the refractive index of the microlens by the predetermined difference, and a second transparent resin layer which has a refractive index different from that of the first transparent resin layer.

(4) The image pickup element according to (3), wherein the transparent resin layer includes an antireflection layer between the first transparent resin layer and the second transparent resin layer.

(5) The image pickup element according to any one of (1) to (4), wherein the microlens is formed using an organic material.

(6) The image pickup element according to any one of (1) to (4), wherein the microlens includes a lens portion formed using an inorganic material, and a planarized portion having substantially the same refractive index as the lens portion and disposed adjacent to the pixel.

(7) The image pickup element according to any one of (1) to (6), wherein the microlens includes an antireflection film.

(8) The imaging element according to (7), wherein the microlens includes a region as an uneven surface of the microlens, the region serving as the antireflection film.

(9) The image pickup element according to any one of (1) to (8), further comprising:

an image pickup lens disposed adjacent to a surface of the sealing glass, the surface being different from a surface of the sealing glass on which the transparent resin layer is disposed.

(10) A method of manufacturing an image pickup element, the method comprising:

a pixel forming step of forming pixels on a semiconductor substrate, the pixels being configured to generate image signals from irradiation light;

a microlens arranging step of arranging microlenses adjacent to the formed pixel, the microlenses collecting incident light to irradiate the pixel with the incident light, and planarizing a surface of the pixel;

a transparent resin layer arranging step of arranging a transparent resin layer adjacent to the arranged microlenses, a refractive index of the transparent resin layer differing from a refractive index of the microlenses by a predetermined difference; and

a sealing step of disposing a sealing glass adjacent to the disposed transparent resin layer, the sealing glass sealing the semiconductor substrate.

List of reference numerals

1 image pickup element

10 pixel array unit

12. 22 semiconductor substrate

13. 23 wiring region

20 signal processing chip

100 pixels

123 insulating film

141 color filter

142 light shielding film

151. 154, 156, 159 micro-lenses

152. 157 lens unit

153. 158 flattening part

155 anti-reflection film

161. 162 transparent resin layer

163 anti-reflection layer

171 sealing glass

181 image pickup lens

1002 image pickup element