JP2017028065A - Solid state image pickup device - Google Patents

Abstract

An object of the present invention is to reduce lens shading while increasing pixel sensitivity. Kind Code: A1 In dichroic filters P1-1 to P1-3, an inclination angle θC about a rotation axis in a column direction CD is larger at one end T1 and the other end T2 of an imaging surface than at a center CP of the imaging surface. , dichroic filters P2-1 to P2-3, the tilt angle .theta.R about the rotation axis in the row direction RD is larger at the other end T4 than at the one end T3 of the imaging surface. [Selection drawing] Fig. 5

Description

  Embodiments described herein relate generally to a solid-state imaging device.

  In recent years, a camera module mounted on a mobile phone or the like is required to be thin and have high resolution. In response to the reduction in the thickness and the resolution of the camera module, the image sensor has been miniaturized. In the image sensor, as the pixel area becomes smaller, the amount of light incident on the pixel decreases, so that the signal amount decreases and the signal-to-noise ratio (SNR) deteriorates. For this reason, the image sensor is desired to achieve high sensitivity by improving light utilization efficiency.

JP 2014-23118 A

  In one embodiment of the present invention, while increasing the sensitivity of a pixel, incident light collected on a pixel area by an optical lens is changed into green light, red light, and blue light because the incident angles to the pixels are different. Color separation characteristics for color separation change. An object of the present invention is to provide a solid-state imaging device that improves the color separation characteristics by reducing the change in the color separation characteristics.

  According to one embodiment of the present invention, the first photoelectric conversion layer provided on the imaging surface with respect to the first wavelength band, and the second photoelectric conversion layer provided on the imaging surface with respect to the second wavelength band. And a color separation element that separates incident light into transmitted light including the first wavelength band and reflected light including the second wavelength band. In the first direction and the second direction orthogonal to each other on the imaging surface, the reflection angle of the reflected light reflected by the color separation element is reduced with respect to the change in the incident angle of the incident light. As described above, the inclination angle of the reflection surface of the color separation element is set.

FIG. 1 is a block diagram illustrating a schematic configuration of the solid-state imaging device according to the first embodiment. FIG. 2 is a circuit diagram illustrating a configuration example of four pixels in the Bayer array of the solid-state imaging device of FIG. FIG. 3 is a plan view illustrating an arrangement example of the pixel cells on the imaging surface of the solid-state imaging device according to the first embodiment. 4A is a cross-sectional view showing a change in the light incident angle on the imaging surface in the row direction RD, and FIG. 4B is a cross-sectional view showing a change in the light incident angle on the imaging surface in the column direction CD. is there. FIG. 5 is a diagram illustrating a method of setting the inclination angle of the dichroic filter of the solid-state imaging device according to the first embodiment. FIG. 6 is a cross-sectional view showing a configuration example of the pixel array section taken along the line A1-A1 ′ of FIG. FIG. 7 is a cross-sectional view showing a configuration example of the pixel array section cut along the line A2-A2 ′ of FIG. FIG. 8 is a diagram illustrating a relationship between the wavelength and the transmittance when the inclination angle of the dichroic filter of the solid-state imaging device according to the first embodiment is changed. FIG. 9A and FIG. 9B are cross-sectional views illustrating a method for manufacturing a color separation element applied to the solid-state imaging device according to the second embodiment. FIG. 10A to FIG. 10C are cross-sectional views illustrating a method for manufacturing a color separation element applied to the solid-state imaging device according to the second embodiment. FIG. 11A and FIG. 11B are cross-sectional views illustrating a method for manufacturing a color separation element applied to the solid-state imaging device according to the second embodiment. FIG. 12A and FIG. 12B are cross-sectional views illustrating a method for manufacturing a color separation element applied to the solid-state imaging device according to the second embodiment. FIGS. 13A and 13B are cross-sectional views illustrating a method for manufacturing a color separation element applied to the solid-state imaging device according to the second embodiment. FIG. 14A and FIG. 14B are cross-sectional views illustrating a method for manufacturing a color separation element applied to the solid-state imaging device according to the second embodiment. FIGS. 15A to 15D are plan views illustrating arrangement examples of pixel cells on the imaging surface of the solid-state imaging device according to the third embodiment. FIG. 16 is a cross-sectional view illustrating a configuration example of the pixel array section cut along the line A3-A3 ′ of FIG. FIG. 17 is a block diagram illustrating a schematic configuration of a signal processing circuit applied to the solid-state imaging device according to the fourth embodiment. FIG. 18 is a block diagram illustrating a schematic configuration of a digital camera to which the solid-state imaging device according to the fifth embodiment is applied. FIG. 19 is a cross-sectional view illustrating a schematic configuration of a camera module to which the solid-state imaging device according to the sixth embodiment is applied.

  Hereinafter, a solid-state imaging device according to an embodiment will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to these embodiments.

(First embodiment)
FIG. 1 is a block diagram illustrating a schematic configuration of the solid-state imaging device according to the first embodiment.
In FIG. 1, in the pixel array section 1, pixels PIX that accumulate photoelectrically converted charges are arranged in a matrix in the row direction RD and the column direction CD. Further, in the pixel array unit 1, a horizontal control line Hlin for performing read control of the pixel PIX is provided in the row direction RD, and a vertical signal line Vlin for transmitting a signal read from the pixel PIX is provided in the column direction CD. Is provided.

  Further, in the solid-state imaging device, the source follower operation is performed between the pixel PIX and the vertical scanning circuit 2 that scans the pixel PIX to be read in the vertical direction, so that the pixel PIX and the vertical signal line Vlin are column by column. A load circuit 3 for reading a signal, a signal component of each pixel PIX for each column by a CDS, a column ADC circuit 4 for AD conversion and output, and a horizontal scanning circuit 5 for scanning a pixel PIX to be read in the horizontal direction A reference voltage generation circuit 6 that outputs a reference voltage VREF to the column ADC circuit 4 and a timing control circuit 7 that controls the timing of reading and storage of each pixel PIX are provided. Note that a ramp wave can be used as the reference voltage VREF. The horizontal scanning circuit 5 can use a horizontal register that transfers the AD conversion value generated by the column ADC circuit 4 in the horizontal direction.

  In the pixel array unit 1, a Bayer array HP in which a set of four pixels PIX is used can be used to colorize a captured image. In the Bayer array HP, two green pixels Gr and Gb are arranged in one diagonal direction, and one red pixel R and one blue pixel B are arranged in the other diagonal direction.

  Then, the pixel PIX is selected in the row direction RD by scanning the pixel PIX in the vertical direction by the vertical scanning circuit 2. Then, the load follower 3 performs a source follower operation with the pixel PIX, whereby a signal read from the pixel PIX is transmitted via the vertical signal line Vlin and sent to the column ADC circuit 4. In the reference voltage generation circuit 6, a ramp wave is set as the reference voltage VREF and sent to the column ADC circuit 4. Then, the column ADC circuit 4 performs a clock counting operation until the signal level read from the pixel PIX and the reset level match the ramp wave level, and the difference between the signal level and the reset level at that time is taken. Thus, the signal component of each pixel PIX is detected by the CDS and output as the output signal S1.

FIG. 2 is a circuit diagram illustrating a configuration example of four pixels in the Bayer array of the solid-state imaging device of FIG.
In FIG. 2, in the Bayer array HP, photodiodes PB, PR, PGr, PGb, row selection transistors TD1, TD2, amplification transistors TA1, TA2, reset transistors TS1, TS2, and read transistors TB, TR, TGr, TGb are provided. ing. The photodiodes PB, PR, PGr, and PGb can be used for the blue pixel B, the red pixel R, and the green pixels Gr and Gb, respectively. Here, the row selection transistor TD1, the amplification transistor TA1, and the reset transistor TS1 are shared by the photodiodes PB and PGr, and the row selection transistor TD2, the amplification transistor TA2 and the reset transistor TS2 are shared by the photodiodes PR and PGb. . The read transistors TB, TR, TGr, and TGb are provided for each of the photodiodes PB, PR, PGr, and PGb. In addition, a floating diffusion FD1 is formed as a detection node at a connection point between the amplification transistor TA1, the reset transistor TS1, and the read transistors TB and TGr. A floating diffusion FD2 is formed as a detection node at a connection point between the amplification transistor TA2, the reset transistor TS2, and the read transistors TR and TGb.

  The source of the read transistor TGr is connected to the photodiode PGr, the source of the read transistor TB is connected to the photodiode PB, the source of the read transistor TR is connected to the photodiode PR, and the source of the read transistor TGb is Are connected to the photodiode PGb. The source of the reset transistor TS1 is connected to the drains of the read transistors TGr and TB, the source of the reset transistor TS2 is connected to the drains of the read transistors TGb and TR, and the reset transistors TS1 and TS2 and the row selection transistors TD1 and TD2 Is connected to the power supply potential VDD. The source of the amplification transistor TA1 is connected to the vertical signal line Vlin1, the gate of the amplification transistor TA1 is connected to the drains of the read transistors TGr and TB, and the drain of the amplification transistor TA1 is connected to the source of the row selection transistor TD1. Has been. The source of the amplification transistor TA2 is connected to the vertical signal line Vlin2, the gate of the amplification transistor TA2 is connected to the drains of the read transistors TGb and TR, and the drain of the amplification transistor TA2 is connected to the source of the row selection transistor TD2. Yes.

  In the example of FIG. 2, the case where the pixels are provided with the row selection transistors TD1 and TD2 has been described, but the pixel without the row selection transistors TD1 and TD2 may be used. In the example of FIG. 2, the 2-pixel 1-cell configuration has been described, but a 4-pixel 1-cell configuration may be used, or an 8-pixel 1-cell configuration may be used, and the configuration is not particularly limited.

FIG. 3 is a plan view illustrating an arrangement example of the pixel cells on the imaging surface of the solid-state imaging device according to the first embodiment.
In FIG. 3, the green pixels Gr and the blue pixels B are alternately arranged so as to be adjacent to each other in the column direction CD. The green pixels Gb and the red pixels R are alternately arranged so as to be adjacent to each other in the column direction CD. A micro lens Z1 is disposed on the blue pixel B, the red pixel R, and the green pixels Gr and Gb. Here, each microlens Z1 can be arranged over an area of two pixels. At this time, the center of each microlens Z1 can be arranged on the green pixels Gr and Gb.
On the green pixel Gr and the blue pixel B, the color separation element P1 is arranged. The color separation element P1 is provided with a dichroic filter DF1. The dichroic filter DF1 is disposed on the green pixel Gr. The dichroic filter DF1 can transmit green light and reflect blue light and red light. The color separation element P1 can cause the reflected light LRA reflected by the dichroic filter DF1 to enter the blue pixel B. Here, the inclination angle of the reflection surface of the dichroic filter DF1 can be set so that both the vertically polarized light and the horizontally polarized light are included in the reflected light LRA. At this time, it is preferable to set the incident angle of the incident light with respect to the reflecting surface of the dichroic filter DF1 within a range of 20 to 30 degrees.
On the green pixel Gb and the red pixel R, the color separation element P2 is arranged. The color separation element P2 is provided with a dichroic filter DF2. The dichroic filter DF2 is disposed on the green pixel Gb. The dichroic filter DF2 can transmit green light and reflect blue light and red light. The color separation element P2 can cause the reflected light LRB reflected by the dichroic filter DF2 to enter the red pixel R. Here, the inclination angle of the reflection surface of the dichroic filter DF2 can be set so that both the vertically polarized light and the horizontally polarized light are included in the reflected light LRB. At this time, the incident angle of the incident light with respect to the reflecting surface of the dichroic filter DF2 is preferably set within a range of 20 to 30 degrees.

4A is a cross-sectional view showing a change in the light incident angle on the imaging surface in the row direction RD, and FIG. 4B is a cross-sectional view showing a change in the light incident angle on the imaging surface in the column direction CD. is there.
4A and 4B, a prism layer PL is provided on the imaging layer SL. In the imaging layer SL, the blue pixel B, the red pixel R, and the green pixels Gr and Gb in FIG. 3 can be provided. The prism layer PL can be provided with the color separation elements P1 and P2 of FIG. Then, the light from the subject OJ is collected by the lens LJ, so that the incident light LI is generated and is incident on the imaging surface of the pixel array unit 1.
Here, as shown in FIG. 4A, in the row direction RD, the center of the imaging surface is CP, one end of the imaging surface is T1, and the other end of the imaging surface is T2. The micro lens Z1-1 is disposed at the center CP of the imaging surface, the micro lens Z1-3 is disposed at one end T1 of the imaging surface, and the micro lens Z1-2 is disposed at the other end T2 of the imaging surface. It shall be. In each of the microlenses Z1-1, Z1-2, and Z1-3, the incident angles of the incident light LI with respect to the perpendicular PJ of the imaging surface are α1, α2, and α3. At this time, the incident angles α2 and α3 are larger than the incident angle α1.
Also, as shown in FIG. 4B, in the column direction CD, the center of the imaging surface is CP, one end of the imaging surface is T3, and the other end of the imaging surface is T4. A micro lens Z2-1 is disposed at the center CP of the imaging surface, a micro lens Z2-3 is disposed at one end T3 of the imaging surface, and a micro lens Z2-2 is disposed at the other end T4 of the imaging surface. It shall be. In each of the microlenses Z2-1, Z2-2, and Z2-3, the incident angles of the incident light LI with respect to the perpendicular PJ of the imaging surface are β1, β2, and β3. At this time, the incident angles β2 and β3 are larger than the incident angle β1.

FIG. 5 is a diagram illustrating a method of setting the inclination angle of the dichroic filter of the solid-state imaging device according to the first embodiment. Note that FIG. 5 shows an example in which the pixels PIX are arranged in a matrix form by 14 × 10 pixels in the row direction RD and the column direction CD.
In FIG. 5, dichroic filters P1-1 to P1-3 are arranged below the microlenses Z1-1, Z1-2, and Z1-3 in FIG. Dichroic filters P2-1 to P2-3 are arranged below the microlenses Z2-1, Z2-2, and Z2-3 in FIG. The dichroic filters P1-1 to P1-3 and P2-1 to P2-3 separate the incident light LI into transmitted light including green light and reflected light including blue light and red light, and transmit the transmitted light to a green pixel. Gr can be made incident. Here, in the dichroic filters P1-1 to P1-3, the inclination angle θC around the rotation axis in the column direction CD is larger at the one end T1 and the other end T2 of the imaging surface than the center CP of the imaging surface. At this time, the magnitude of the inclination angle θC can be changed according to the parabolic curve PAR from the center CP of the imaging surface toward one end T1 and the other end T2 of the imaging surface. In the dichroic filters P2-1 to P2-3, the inclination angle θR around the rotation axis in the row direction RD is larger at the other end T4 than at one end T3 of the imaging surface. At this time, the magnitude of the inclination angle θR can be changed according to the ramp wave RAP from one end T3 to the other end T4 of the imaging surface.
Thereby, the inclination angle θC of the reflection surface of each of the dichroic filters P1-1 to P1-3 and P2-1 to P2-3 so that the changes in the incident angles α1 to α3 and β1 to β3 of the incident light LI are alleviated. , ΘR can be set. For this reason, the fluctuation | variation of the incident light quantity to the pixel PIX resulting from the change of incident angle (alpha) 1- (alpha) 3 of (beta) 1- (beta) 3 of incident light LI can be reduced, and the color separation characteristic of a dichroic filter can be improved.

FIG. 6 is a cross-sectional view showing a configuration example of the pixel array section taken along the line A1-A1 ′ of FIG. FIG. 6 shows the case where the incident angle of the incident light LI changes in the column direction CD of FIG.
In FIG. 6, photodiodes PB and PGr are alternately formed along the A1-A1 ′ line in the semiconductor layer SB. Note that the material of the semiconductor layer SB can be selected from, for example, Si, Ge, SiGe, SiC, SiSn, PbS, GaAs, InP, InGaAsP, GaP, GaN, and ZnSe. Further, the semiconductor layer SB can be set to p-type. The photodiodes PB and PGr can be set to n-type. A blue filter FB is provided on the photodiode PB, and a green filter FGr is provided on the photodiode PGr.

On the green filter FGr, dichroic filters P2-2, P2-1, and P2-3 are provided from one end T4 to the other end T3 of the imaging surface. As the dichroic filters P2-2, P2-1, and P2-3, multilayer interference filters can be used. The multilayer interference filter can be constructed by sandwiching a spacer layer with a λ / 4 multilayer film, and can transmit light in a wavelength region corresponding to the optical film thickness of the spacer layer. Note that λ is called a set wavelength and is the center wavelength of the reflection wavelength region of the λ / 4 multilayer film. For example, when the set wavelength λ is 550 nm, the optical film thickness of the dielectric layers constituting the λ / 4 multilayer film is 137.5 nm. Here, the optical film thickness is an index obtained by multiplying the physical film thickness of the dielectric layer by the refractive index. For example, the dichroic filters P2-2, P2-1, and P2-3 include two types of dielectric layers, a high refractive index layer made of titanium oxide (TiO ₂ ) and a low refractive index layer made of silicon oxide (SiO ₂ ). A laminated film in which are alternately laminated can be used. Since the refractive indexes of titanium oxide and silicon oxide are 2.51 and 1.45, respectively, in order to set the optical film thickness to 137.5 nm, the physical film thicknesses of the titanium oxide layer and the silicon oxide layer are 54.7 nm, respectively. It may be 94.8 nm.

Further, silicon oxide can be used for the spacer layer. The physical film thickness of the spacer layer is 0 nm in the dichroic filters P2-2, P2-1, and P2-3 that transmit green light. Note that the two titanium oxide layers sandwiching the spacer layer having a physical thickness of 0 nm in the dichroic filters P2-2, P2-1, and P2-3 that transmit green light have a physical thickness of 109.4 nm as a whole.
The total number of layers of the dichroic filters P2-2, P2-1, and P2-3, that is, the total number of layers including the λ / 4 multilayer film and the spacer layer is determined by the dichroic filter P2-2 that transmits green light. , P2-1 and P2-3 can be realized with 6 to 20 layers.
Dichroic filters P2-2, P2-1, and P2-3 separate incident light LI into transmitted light LT2, LT1, and LT3 including green light and reflected light LR2, LR1, and LR3 including blue light and red light, respectively. can do. Here, the inclination angles of the reflecting surfaces of the dichroic filters P2-2, P2-1, and P2-3 are set to θR2, θR1, and θR3, respectively. The inclination angles θR2, θR1, and θR3 can be set so that changes in the incident angles β1 to β3 of the incident light LI are alleviated. That is, the dichroic filters P2-2, P2-1, and P2-3 can change the reflection angles of the reflected lights LR2, LR1, and LR3 so that the changes in the incident angles β1 to β3 of the incident light LI are reduced. it can. For example, the tilt angles θR2, θR1, and θR3 can be set so that each of the reflected lights LR2, LR1, and LR3 can enter the photodiode PB perpendicularly even when the incident angles β1 to β3 of the incident light LI change. it can. At this time, the relationship θR2>θR1> θR3 can be satisfied.

  Further, in the photodiode PGr adjacent to each other, when the incident angle of the incident light LI changes from β2 to β2-Δβ2, the inclination angle of the inclined surface of the dichroic filter P2-2 can be changed from θR2 to θR2-ΔθR2. . Further, in the adjacent photodiodes PGr, when the incident angle of the incident light LI changes from β1 to β1-Δβ1, the inclination angle of the inclined surface of the dichroic filter P2-1 can be changed from θR1 to θR1-ΔθR1. . Further, in the photodiodes PGr adjacent to each other, when the incident angle of the incident light LI changes from β3 to β3 + Δβ3, the inclination angle of the inclined surface of the dichroic filter P2-3 can be changed from θR3 to θR3 + ΔθR3. As shown in FIG. 5, when the inclination angles θR2, θR1, and θR3 are changed according to the ramp wave RAP, Δβ1 = Δβ2 = Δβ3 can be established.

Reflective blocks BK2, BK1, and BK3 are provided on the blue filter FB so as to cover the dichroic filters P2-2, P2-1, and P2-3, respectively. The reflection blocks BK2, BK1, and BK3 can cause the reflected lights LR2, LR1, and LR3 to enter the photodiode PB, respectively. A material transparent to the incident light LI can be used for the reflection blocks BK2, BK1, and BK3. For example, the material of the reflection blocks BK2, BK1, and BK3 may be made of SiO ₂ or SiN. Reflective materials RF2, RF1, and RF3 are provided on the reflective blocks BK2, BK1, and BK3, respectively. The reflection blocks BK2, BK1, and BK3 can support the reflection materials RF2, RF1, and RF3 on the blue filter FB. At this time, the reflectors RF2, RF1, and RF3 can be arranged so as to avoid the incident path of the incident light LI to the dichroic filters P2-2, P2-1, and P2-3. As the material of the reflection materials RF2, RF1, and RF3, for example, a metal such as Al or Ag can be used. The inclination angles of the reflection surfaces of the reflection blocks BK2, BK1, and BK3 can be set to θF2, θF1, and θF3, respectively. At this time, the relationship θF2 = θF1 = θF3 can be satisfied. The inclination angles θF2, θF1, and θF3 may be different from each other.

A planarizing film 11 is provided on the reflective blocks BK2, BK1, and BK3 and on the reflective materials RF2, RF1, and RF3. A spacer film 12 is provided on the planarizing film 11. The planarizing film 11 and the spacer film 12 can be made of a material that is transparent to the incident light LI. For example, the material for the planarizing film 11 and the spacer film 12 may be SiO ₂ , SiN, or a transparent resin such as acrylic or polycarbonate. On the spacer film 12, microlenses Z2-2, Z2-1, and Z2-3 are provided corresponding to the dichroic filters P2-2, P2-1, and P2-3, respectively.
The incident light LI is collected by the microlenses Z2-2, Z2-1, and Z2-3, and enters the dichroic filters P2-2, P2-1, and P2-3, respectively. Then, the incident light LI is separated into transmitted light LT2, LT1, LT3 and reflected light LR2, LR1, LR3 by the dichroic filters P2-2, P2-1, P2-3, respectively. The transmitted lights LT2, LT1, and LT3 enter the green filter FGr, and green light is selected from the transmitted lights LT2, LT1, and LT3, and then enters the photodiode PGr. On the other hand, the reflected lights LR2, LR1, and LR3 are reflected in the reflection blocks BK2, BK1, and BK3, and enter the blue filter PB. And after selecting blue light from reflected light LR2, LR1, LR3, it injects into photodiode PB. Here, by providing a green filter FGr under the dichroic filters P2-2, P2-1, and P2-3 and providing a blue filter PB under the reflection blocks BK2, BK1, and BK3, the dichroic filters P2-2 and P2-1 are provided. , P2-3 color supplement can be supplemented. For this reason, even when the color separation of the dichroic filters P2-2, P2-1, and P2-3 is not sufficient, the color reproducibility can be improved.
The formation positions of the microlenses (Z2-2, Z2-1, Z2-3) are shifted to the incident angle side of the incident light LI, thereby forming the dichroic filters (P2-2, P2-1, P2-3). ) Can be improved.

FIG. 7 is a cross-sectional view showing a configuration example of the pixel array section cut along the line A2-A2 ′ of FIG. FIG. 7 shows the case where the incident angle of the incident light LI changes in the column direction CD of FIG.
In FIG. 7, photodiodes PR and PGb are alternately formed in the semiconductor layer SB along the line A2-A2 ′. The photodiodes PR and PGb can be set to n-type. A red filter FR is provided on the photodiode PR, and a green filter FGb is provided on the photodiode PGb. Also along the line A2-A2 ′, the incident angle of the incident light LI changes in the column direction CD as in the case along the line A1-A1 ′. For this reason, the same structure as FIG. 6 can be provided on the red filter FR and the green filter FGb.

The incident light LI is collected by the microlenses Z2-2, Z2-1, and Z2-3, and enters the dichroic filters P2-2, P2-1, and P2-3, respectively. Then, the incident light LI is separated into transmitted light LT2, LT1, LT3 and reflected light LR2, LR1, LR3 by the dichroic filters P2-2, P2-1, P2-3, respectively. Then, the transmitted lights LT2, LT1, and LT3 enter the green filter FGb, and green light is selected from the transmitted lights LT2, LT1, and LT3, and then enters the photodiode PGb. On the other hand, the reflected lights LR2, LR1, and LR3 are reflected in the reflection blocks BK2, BK1, and BK3 and enter the red filter PR. And after selecting red light from reflected light LR2, LR1, LR3, it injects into photodiode PR. Here, by providing the green filter FGb under the dichroic filters P2-2, P2-1, and P2-3 and providing the red filter PR under the reflection blocks BK2, BK1, and BK3, the dichroic filters P2-2 and P2-1 are provided. , P2-3 color supplement can be supplemented. For this reason, even when the color separation of the dichroic filters P2-2, P2-1, and P2-3 is not sufficient, the color reproducibility can be improved.
In the above-described embodiment, the configuration in which the reflected light LRA of the color separation element P1 and the reflected light LRB of the color separation element P2 are reflected in the column direction CD is shown, but the reflected light LRA and the color separation element of the color separation element P1 are shown. The configuration may be such that the reflected light LRB of P2 is reflected in the row direction RD. In this case, the magnitude of the inclination angle θC can be changed according to the ramp wave RAP, and the magnitude of the inclination angle θR can be changed according to the parabolic curve PAR.

FIG. 8 is a diagram illustrating a relationship between the wavelength and the transmittance when the inclination angle of the dichroic filter of the solid-state imaging device according to the first embodiment is changed. In FIG. 8, the inclination angles are 15 °, 20 °, 25 °, 30 °, and 35 °.
In FIG. 8, when the inclination angle of the dichroic filter is different, the transmittance of the dichroic filter changes. In particular, the change in transmittance is large with green light (wavelength = around 500 to 560 nm).

(Second Embodiment)
9 (a), FIG. 9 (b), FIG. 10 (a) to FIG. 10 (c), FIG. 11 (a) to FIG. 14 (a) and FIG. 11 (b) to FIG. It is sectional drawing which shows the manufacturing method of the color separation element applied to the solid-state imaging device which concerns on 2 embodiment. In this embodiment, the manufacturing method having the configuration shown in FIG. 6 is shown.
In FIG. 9A, photodiodes PB and PGr are alternately formed in the semiconductor layer SB. Then, the blue filter FB is formed on the photodiode PB, and the green filter FGr is formed on the photodiode PGr. Next, the interlayer insulating film 21 is formed on the blue filter FB and the green filter FGr by a method such as CVD. For example, SiO ₂ can be used as the material of the interlayer insulating film 21.

Next, as shown in FIG. 9B, a resist film 22 is formed on the interlayer insulating film 21 by a method such as spin coating.
Next, as shown in FIGS. 10A to 10C, the resist film 22 is exposed through an exposure mask MK, whereby the latent images 22-2, 22-1, and 22- 3 is formed. At this time, the latent images 22-2, 22-1, and 22-3 correspond to the inclination angles of the inclined surfaces of the dichroic filters P2-2, P2-1, and P2-3, respectively, in the film thickness direction of the resist film 22. Can have an exposure distribution. In order to give the resist film 22 an exposure distribution in the film thickness direction, light-shielding layers PT2, PT1, and PT3 having different roughnesses are provided on the exposure mask MK corresponding to the positions of the latent images 22-2, 22-1, and 22-3. be able to.

Next, as shown in FIG. 11A, the resist films 22 on which the latent images 22-2, 22-1, and 22-3 are developed are developed, so that the inclined surfaces 23-2, 23-1, and 23 are formed. A resist film 23 having −3 is formed on the interlayer insulating film 21.
Next, as shown in FIG. 11B, the interlayer insulating film 21 is anisotropically etched through the resist film 23, so that the inclined surfaces 21-2, 21-1, and 21-3 are changed to the interlayer insulating film 21. To form. In order to form the inclined surfaces 21-2, 21-1, and 21-3 on the interlayer insulating film 21, nanoimprint may be used. At this time, the template used for nanoimprinting can have recesses corresponding to the inclined surfaces 21-2, 21-1, and 21-3.

Next, as shown in FIG. 12A, the multilayer interference structure 26 is formed on the interlayer insulating film 21 by a method such as sputtering. Multilayer interference structure 26, for example, may be a stack structure of a low refractive index layer 25 composed of titanium oxide high refractive index layer 24 and a silicon oxide consisting of _{(TiO 2) (SiO 2)} . And the resist pattern 27 arrange | positioned on inclined surface 21-2, 21-1, 21-3 is formed on the multilayer film interference structure 26 by using a photolithographic technique.
Next, as shown in FIG. 12B, the multilayer interference structure 26 is anisotropically etched using the resist pattern 27 as a mask, so that the dichroic filters P2-2, P2-1 and P2-3 are photodiodes PGr. Form on top.

Next, as shown in FIG. 13A, an insulating film 28 that covers the dichroic filters P2-2, P2-1, and P2-3 is formed by a method such as CVD. For the insulating film 28, a material having a refractive index different from that of the multilayer interference structure 26 can be used. For example, the material of the insulating film 28 can be SiN.
Next, as shown in FIG. 13B, the insulating film 28 is anisotropically etched so that the insulating film 28 remains on the side walls of the dichroic filters P2-2, P2-1, and P2-3. The insulating film 28 on the inclined surfaces of the dichroic filters P2-2, P2-1, and P2-3 and on the blue filter FB is removed.
Next, an insulating film is formed on the dichroic filters P2-2, P2-1, P2-3 and the blue filter FB by a method such as CVD. Then, the insulating film is patterned by using a photolithography technique and an etching technique, and reflection blocks BK2, BK1, and BK3 are formed on the dichroic filters P2-2, P2-1, and P2-3 and on the blue filter FB. At this time, the reflecting blocks BK2, BK1, and BK3 can be provided with reflecting surfaces having inclination angles θF2, θF1, and θF3, respectively. This reflective surface can be formed by a method similar to that shown in FIGS.

Next, as shown in FIG. 14A, a metal film 29 is formed on the reflection blocks BK2, BK1, and BK3 by a method such as sputtering. Then, the metal film 29 is planarized by a method such as CMP.
Next, as shown in FIG. 14B, the metal film 29 is patterned by using the photolithography technique and the etching technique, and the reflection materials RF2, RF1, and RF3 are formed on the reflection blocks BK2, BK1, and BK3, respectively. .

(Third embodiment)
FIGS. 15A to 15D are plan views illustrating arrangement examples of pixel cells on the imaging surface of the solid-state imaging device according to the third embodiment.
In FIG. 15D, the blue pixel B and the red pixel R are respectively arranged for two pixels in a direction inclined by 45 ° with respect to the column direction CD. Further, as shown in FIG. 15C, the color separation element P3 is disposed on the blue pixel B and the red pixel R. The color separation element P3 is provided with a dichroic filter DF3. The dichroic filter DF3 is disposed on the red pixel R. The dichroic filter DF3 can transmit red light and reflect blue light. The color separation element P3 can cause the reflected light LRC reflected by the dichroic filter DF3 to enter the blue pixel B. Further, as shown in FIG. 15B, the green pixel G is arranged on the color separation element P3 so as to occupy the area of two pixels. As a material of the green pixel G, an inorganic material or an organic material that is mainly sensitive to green can be used. As an organic photoelectric material that absorbs green light and is transparent to red light and blue light, a perylene compound, a quinacridone compound, rhodamine 6G, or the like can be used. In order to collect charges photoelectrically converted by the green pixel G, transparent electrodes can be provided above and below the green pixel G. Further, as shown in FIG. 15A, on the green pixel G, a micro lens Z1 is disposed. Here, the inclined surfaces of the dichroic filter DF3 can be provided with inclination angles θC and θR as in FIG.

FIG. 16 is a cross-sectional view illustrating a configuration example of the pixel array section cut along the line A3-A3 ′ of FIG. Note that FIG. 16 shows the case where the incident angle of the incident light LI changes in the column direction CD of FIG.
In FIG. 16, photodiodes PB and PR are alternately formed along the A3-A3 ′ line in the semiconductor layer SB ′. A blue filter FB is provided on the photodiode PB, and a red filter FR is provided on the photodiode PR.

  On the red filter FR, dichroic filters P3-2, P3-1, and P3-3 are provided from one end T4 to the other end T3 of the imaging surface. The dichroic filters P 3-2, P 3-1, and P 3-3 transmit incident light LI to transmitted light LT 2 ′, LT 1 ′, LT 3 ′ including red light and reflected light LR 2 ′, LR 1 ′, LR 3 ′ including blue light. Can be separated from each other. Here, the inclination angles of the reflecting surfaces of the dichroic filters P3-2, P3-1, and P3-3 are set to θR2, θR1, and θR3, respectively. The inclination angles θR2, θR1, and θR3 can be set so that changes in the incident angles β1 to β3 of the incident light LI are alleviated. That is, the dichroic filters P 3-2, P 3-1, and P 3-3 change the reflection angles of the reflected lights LR 2 ′, LR 1 ′, and LR 3 ′ so that changes in the incident angles β 1 to β 3 of the incident light LI are alleviated. Can be made. For example, the inclination angles θR2, θR1, and θR3 are set so that the reflected lights LR2 ′, LR1 ′, and LR3 ′ can be incident on the photodiode PB perpendicularly even when the incident angles β1 to β3 of the incident light LI change. can do. At this time, the relationship θR2> θR1> θR3 can be satisfied.

  Reflective blocks BK2, BK1, and BK3 are provided on the blue filter FB so as to cover the dichroic filters P3-2, P3-1, and P3-3, respectively. The reflection blocks BK2, BK1, and BK3 can cause the reflected lights LR2 ′, LR1 ′, and LR3 ′ to enter the photodiode PB, respectively. Reflective materials RF2, RF1, and RF3 are provided on the reflective blocks BK2, BK1, and BK3, respectively.

A transparent electrode 13 is provided on the reflection blocks BK2, BK1, and BK3 and on the reflection materials RF2, RF1, and RF3. The transparent electrode 13 is separated for each green pixel G. On the transparent electrode 13, a photoelectric film 14 having a sensitivity to green is provided. A transparent electrode 15 is provided on the photoelectric film 14. The transparent electrode 15 can be provided in common for the green pixel G. On the transparent electrode 15, microlenses Z2-2, Z2-1, and Z2-3 are provided corresponding to the dichroic filters P3-2, P3-1, and P3-3, respectively.
Then, the incident light LI is condensed by the microlenses Z2-2, Z2-1, and Z2-3, and enters the photoelectric film 14, respectively. Then, green light is absorbed by the photoelectric film 14, and electric charges are generated according to the intensity of the green light. On the other hand, the blue light and the red light that are not absorbed by the photoelectric film 14 are incident on the dichroic filters P3-2, P3-1, and P3-3. Then, the incident light LI is separated into transmitted light LT2 ′, LT1 ′, LT3 ′ and reflected light LR2 ′, LR1 ′, LR3 ′ by the dichroic filters P3-2, P3-1, P3-3. At this time, the transmitted light LT2 ′, LT1 ′, and LT3 ′ may include red light, and the reflected light LR2 ′, LR1 ′, and LR3 ′ may include blue light. Then, the transmitted light LT2 ′, LT1 ′, LT3 ′ is incident on the red filter FR, and after the red light is selected from the transmitted light LT2 ′, LT1 ′, LT3 ′, it is incident on the photodiode PR. On the other hand, the reflected lights LR2 ′, LR1 ′, and LR3 ′ are reflected in the reflection blocks BK2, BK1, and BK3, and enter the blue filter PB. And after selecting blue light from reflected light LR2 ', LR1', LR3 ', it injects into photodiode PB. Here, the photoelectric film 14 is subjected to photoelectric conversion of green light, and the dichroic filters P 3-2, P 3-3 are separated from the blue light and the red light by the dichroic filters P 3-2, P 3-1, P 3-3. -1, P3-3, it becomes unnecessary to separate green light. For this reason, dichroic filters P3-2, P3-1, and P3-3 are used to convert green light having a large variation in transmittance when the inclination angles of the inclined surfaces of the dichroic filters P3-2, P3-1, and P3-3 are changed. Therefore, it is possible to reduce the variation in transmittance in FIG.

(Fourth embodiment)
FIG. 17 is a block diagram illustrating a schematic configuration of a signal processing circuit applied to the solid-state imaging device according to the fourth embodiment.
17, the solid-state imaging device includes a sensor unit 32, an AD conversion unit 33, line memories 34, 39, and 46, a flaw correction unit 35, a noise cancellation unit 36, a lens shading correction unit 37, a digital amplifier 38, and a pixel interpolation unit. 40, a color matrix unit 41, a white balance / gain adjustment unit 42, a band pass filter 43, a gamma correction unit 44, a YUV conversion unit 45, a contour enhancement unit 47, a gain correction unit 48, and a matrix correction unit 49 are provided. A lens 31 is provided in front of the sensor unit 32. The sensor unit 32 and the AD conversion unit 33 can use the configuration shown in FIG.

  The sensor unit 32 photoelectrically converts the subject for each pixel to generate a pixel signal. The AD conversion unit 33 converts the pixel signal output from the sensor unit 32 into a digital value. The line memory 34 holds the pixel signal read from the pixel for each line. The flaw correction unit 35 corrects the pixel signal read from the pixel so that the flaw of the pixel is repaired. The noise cancellation unit 36 performs filtering of the pixel signal read from the pixel. The lens shading correction unit 37 compensates for attenuation of the amount of light at the peripheral portion of the lens 31 (peripheral amount of light attenuation due to the cosine fourth law of the optical lens). The digital amplifier 38 amplifies the pixel signal read from the pixel. The line memory 39 holds the pixel signal amplified by the digital amplifier 38 for each line. The pixel interpolation unit 40 interpolates the pixel signal based on the pixel signals of the peripheral pixels. The color matrix unit 41 adjusts the color of the pixel signal based on a matrix operation on the RGB signals. The white balance / gain adjustment unit 42 adjusts the white balance and gain of the pixel signal read from the pixel. The band pass filter 43 extracts a predetermined frequency band from the pixel signal amplified by the digital amplifier 38. The gamma correction unit 44 performs gamma correction of the pixel signal. The YUV converter 45 converts the RGB signal into a YUV signal. The contour emphasizing unit 47 performs contour emphasis on the pixel signal. The gain correction unit 48 corrects the gain of the digital amplifier 38 with respect to the blue signal, the red signal, and the green signal based on the inclination angles of the reflection surfaces of the dichroic filters P1-1 to P1-3 and P2-1 to P2-3. . Here, the gain correction unit 48 can correct the gain of the digital amplifier 38 in accordance with the parabolic curve PAR from the center CP of the imaging surface toward one end T1 and the other end T2 of the imaging surface in the row direction RD. In the column direction CD, the gain correction unit 48 can correct the gain of the digital amplifier 38 according to the ramp wave RAP from one end T3 to the other end T4 of the imaging surface. The matrix correction unit 49 is a color correction coefficient of the color matrix unit 41 for the blue signal, the red signal, and the green signal based on the inclination angles of the reflection surfaces of the dichroic filters P1-1 to P1-3 and P2-1 to P2-3. Correct. Here, in the row direction RD, the matrix correction unit 49 can correct the color correction coefficient of the color matrix unit 41 according to the parabolic curve PAR from the center CP of the imaging surface toward one end T1 and the other end T2 of the imaging surface. it can. Further, the matrix correction unit 49 can correct the color correction coefficient of the color matrix unit 41 in accordance with the ramp wave RAP from the one end T3 to the other end T4 of the imaging surface in the column direction CD.

Then, when the incident light LI is incident on the sensor unit 32 via the lens 31, imaging is performed. The pixel signal read from the pixel is converted into a digital value by the AD converter 33 and held in the line memory 34. Then, the flaw correction unit 35 and the noise cancellation unit 36 perform flaw correction and noise cancellation of the pixel signal read from the pixel based on the pixel signal held in the line memory 34. Then, after the pixel signal is amplified in the digital amplifier 38, it is held in the line memory 39. At this time, the gain correction unit 48 corrects the gain of the digital amplifier 38 based on the tilt angles of the reflecting surfaces of the dichroic filters P1-1 to P1-3 and P2-1 to P2-3. Then, the pixel interpolation unit 40 interpolates the pixel signals based on the pixel signals held in the line memory 39, and then the color matrix unit 41 performs color adjustment of the pixel signals. At this time, the matrix correction unit 49 corrects the color correction coefficient of the color matrix unit 41 based on the inclination angles of the reflection surfaces of the dichroic filters P1-1 to P1-3 and P2-1 to P2-3. Further, after the gamma correction of the pixel signal is performed in the gamma correction unit 44, the RGB signal is converted into a YUV signal in the YUV conversion unit 45 and held in the line memory 46. The UV signal is output via the line memory 46. For the Y signal, a predetermined frequency band is extracted from the pixel signal held in the line memory 39 by the band pass filter 43. Then, the contour emphasizing unit 47 performs contour emphasis based on the signal extracted by the bandpass filter 43 and outputs it as a Y signal. Further, the white balance / gain adjustment unit 42 adjusts the white balance and gain of the pixel signal color-adjusted by the color matrix unit 41, and instructs the digital amplifier 38 to reflect the adjustment result in the pixel signal. The
Here, by providing the gain correction unit 48 and the matrix correction unit 49, as shown in FIG. 8, according to the change in the inclination angle of the reflection surfaces of the dichroic filters P1-1 to P1-3 and P2-1 to P2-3. Even when the transmittance fluctuates, it is possible to suppress pixel signal variation based on the transmittance variation.

(Fifth embodiment)
FIG. 18 is a block diagram illustrating a schematic configuration of a digital camera to which the solid-state imaging device according to the fifth embodiment is applied.
In FIG. 18, the digital camera 51 includes a camera module 52 and a post-processing unit 53. The camera module 52 includes an imaging optical system 54 and a solid-state imaging device 55. The post-processing unit 53 includes an image signal processor (ISP) 56, a storage unit 57, and a display unit 58. Note that the line memories 34, 39 and 46, the flaw correction unit 35, the noise cancellation unit 36, the lens shading correction unit 37, the digital amplifier 38, the pixel interpolation unit 40, the color matrix unit 41, and the white balance / gain adjustment unit 42 in FIG. The band-pass filter 43, the gamma correction unit 44, the YUV conversion unit 45, the contour enhancement unit 47, the gain correction unit 48, and the matrix correction unit 49 can be provided in the image signal processor 56. Further, at least a part of the configuration of the ISP 56 may be integrated into one chip together with the solid-state imaging device 55. The solid-state imaging device 55 can use the configuration shown in FIG.

  The imaging optical system 54 takes in the incident light LI and forms a subject image. The solid-state imaging device 55 captures a subject image. The ISP 56 performs signal processing on an image signal obtained by imaging with the solid-state imaging device 55. The storage unit 57 stores an image that has undergone signal processing in the ISP 56. The storage unit 57 outputs an image signal to the display unit 58 in accordance with a user operation or the like. The display unit 58 displays an image according to an image signal input from the ISP 56 or the storage unit 57. The display unit 58 is, for example, a liquid crystal display. In addition to the digital camera 51, the camera module 52 may be applied to an electronic device such as a camera-equipped mobile terminal or a smartphone.

(Sixth embodiment)
FIG. 19 is a cross-sectional view illustrating a schematic configuration of a camera module to which the solid-state imaging device according to the sixth embodiment is applied.
Incident light LI condensed by the lens LJ travels to the image sensor 107 through the main mirror 101, the sub mirror 102, and the mechanical shutter 106. The camera module 100 captures a subject image with the image sensor 107. The imaging element 107 can use the configuration shown in FIG.
The light reflected by the sub mirror 102 travels to the autofocus (AF) sensor 103. The camera module 100 performs focus adjustment using the detection result of the AF sensor 103. The light reflected by the main mirror 101 travels to the finder 108 through the lens 104 and the prism 105.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  1 pixel array unit, 2 vertical scanning circuit, 3 load circuit, 4 column ADC circuit, 5 horizontal scanning circuit, 6 reference voltage generating circuit, 7 timing control circuit, Vlin vertical signal line, Hlin horizontal control line, PIX pixel, HP Bayer Array, Gr, Gb Green pixel, R Red pixel R, B Blue pixel

Claims (5)

A first photoelectric conversion layer provided on the imaging surface with respect to the first wavelength band;
A second photoelectric conversion layer provided on the imaging surface with respect to a second wavelength band;
A color separation element that separates incident light into transmitted light including the first wavelength band and reflected light including the second wavelength band;
In the first direction and the second direction orthogonal to each other on the imaging surface, the reflection angle of the reflected light reflected by the color separation element is reduced with respect to the change in the incident angle of the incident light. Thus, the solid-state imaging device in which the inclination angle of the reflective surface of the color separation element is set. The first photoelectric conversion layer and the second photoelectric conversion layer are arranged in a matrix in a first direction and a second direction orthogonal to each other on the imaging surface,
The first photoelectric conversion layer and the second photoelectric conversion layer are disposed adjacent to each other in the first direction,
The transmitted light transmitted through the color separation element is incident on the first photoelectric conversion layer, and the reflected light reflected by the color separation element is incident on the second photoelectric conversion layer,
In the first direction, the magnitude of the inclination angle around the rotation axis in the second direction increases from one end to the other end of the imaging surface in a ramp shape,
2. The solid-state imaging device according to claim 1, wherein in the second direction, the inclination angle around the rotation axis in the first direction increases in a parabolic manner from the center of the imaging surface toward both ends. A first photoelectric conversion layer provided on the imaging surface with respect to the first wavelength band;
A second photoelectric conversion layer provided adjacent to the first photoelectric conversion layer with respect to a second wavelength band;
A third photoelectric conversion layer provided on the imaging surface with respect to the first wavelength band;
A fourth photoelectric conversion layer provided adjacent to the third photoelectric conversion layer with respect to the second wavelength band;
The incident light is provided on the first photoelectric conversion layer and separated into transmitted light including the first wavelength band and reflected light including the second wavelength band, and the transmitted light is transmitted to the first photoelectric conversion layer. A first color separation element that causes the reflected light to enter the second photoelectric conversion layer; and
Provided on the third photoelectric conversion layer, separates incident light into transmitted light including the first wavelength band and reflected light including the second wavelength band, and transmits the transmitted light to the third photoelectric conversion layer. And a second color separation element that makes the reflected light incident on the fourth photoelectric conversion layer,
In the first direction and the second direction orthogonal to each other on the imaging surface, the reflection angle of the reflected light reflected by the color separation element is reduced with respect to the change in the incident angle of the incident light. Thus, the solid-state imaging device in which the inclination angle of the reflective surface of the color separation element is set. A first color filter provided on the first photoelectric conversion layer and having selectivity in the first wavelength band;
4. The solid-state imaging device according to claim 1, further comprising: a second color filter provided on the second photoelectric conversion layer and having selectivity in the second wavelength band. 5. A gain correction unit that corrects gains of the first color signal in the first wavelength band and the second color signal in the second wavelength band based on the inclination angle of the reflection surface of the color separation element;
At least one of matrix correction units that correct color correction coefficients of the first color signal in the first wavelength band and the second color signal in the second wavelength band based on the tilt angle of the reflection surface of the color separation element. 5. The solid-state imaging device according to claim 1, comprising:

Images