JP2005347475A - Solid state image sensor and solid state imaging system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state image sensor and solid-state imaging system which has a high-quality photoelectric conversion layer and has a high sensitivity and no afterimage. <P>SOLUTION: The solid-state image sensor is such that a photoelectric conversion 14 is formed on a signal transfer circuit board 12 (silicon substrate) which is such that a signal transfer circuit (not shown in Figure) is formed on an Si substrate. The photoelectric conversion 14 consists of a photoelectric conversion layer 20 comprising a single-layer type compound semiconductor layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a solid-state imaging device that can be used for a digital camera, a video camera, a facsimile, a scanner, a copying machine, and other optical sensors such as bio and chemical sensors. In particular, the present invention relates to a solid-state imaging device having a single-layer photoelectric conversion layer and a solid-state imaging system.

  Conventionally, in a solid-state imaging device having a structure in which a photoelectric conversion layer is provided in substantially the same plane as the charge transfer path, the light loss in the color filter and the aperture of the light receiving device are about the same as the wavelength of light as the pixels are highly integrated There is a disadvantage that the size is reduced and light is less likely to be guided to the photoelectric conversion layer. As described above, the conventional solid-state imaging device has a problem that the light use efficiency is low.

  In order to solve this problem, it has been proposed that the photoelectric conversion layer has a laminated structure (see JP-A-5-152554 and JP-A-9-64406). In this proposal, since the photoelectric conversion layer is composed of amorphous or polycrystalline, the afterimage and dark current are large, and the actual situation is that the photoelectric conversion layer has not been put into practical use.

  In addition, epitaxial growth on a silicon substrate has a high temperature and has practical problems, and crystals that can be grown on a silicon substrate at a low temperature have been studied, but a good quality film has not been obtained. .

JP-A-5-152554 JP-A-9-64406

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, an object of the present invention is to provide a solid-state imaging device and a solid-state imaging system that have a high-quality photoelectric conversion layer, have high sensitivity, and have no afterimage.

The above problem is solved by the following means. That is,
The individual imaging device of the present invention is
A photoelectric conversion unit that generates a signal by incident light from outside;
A semiconductor substrate provided with a signal transfer circuit for reading the signal generated from the photoelectric conversion unit, the photoelectric conversion unit being provided on the surface;
In a solid-state imaging device having
The photoelectric conversion layer that constitutes the photoelectric conversion part is configured by a single layer structure of a compound semiconductor layer.

  In the solid-state imaging device of the present invention, the photoelectric conversion layer constituting the photoelectric conversion unit is configured with a single layer structure of a compound semiconductor layer. Since this compound semiconductor layer has good crystallinity and lattice matching, the charge can move at high speed, there is little dark current, and it is difficult for defects to occur, so that the area can be increased. For this reason, the sensitivity is high and the afterimage is reduced. In addition, since the photoelectric conversion part is provided on the semiconductor substrate, the light receiving surface can be formed larger than the case where the photoelectric conversion part is provided on the same surface as the signal transfer circuit provided on the semiconductor substrate. Is also possible.

  In the solid-state imaging device of the present invention, it is preferable that the semiconductor substrate is a silicon substrate, and the light conversion layer is formed of a GaAs layer, an InGaP layer, or an InGaAsP layer lattice-matched to GaAs. In this configuration, since a high-quality photoelectric conversion layer having a light absorption wavelength (band gap) in the visible region is provided on the silicon substrate, the visible region can be received with high sensitivity and no afterimage. .

  In the solid-state imaging device of the present invention, it is preferable that the semiconductor substrate is made of a silicon substrate, and the light conversion layer is composed of an InGaN layer, a GaN layer, or an AlGaN layer. In this configuration, since a high-quality photoelectric conversion layer having a band gap in the visible to ultraviolet region is provided on the silicon substrate, it is possible to receive ultraviolet light with high sensitivity and no afterimage.

  In the solid-state imaging device of the present invention, it is preferable that the semiconductor substrate is made of a silicon substrate, and the light conversion layer includes an InP layer, an InGaAs layer, and an InAlAs layer that are lattice-matched to InP. In this configuration, since a high-quality photoelectric conversion layer having a band gap in the infrared region is provided on the silicon substrate, infrared light can be received with high sensitivity and no afterimage.

  In the solid-state imaging device of the present invention, it is preferable that the photoelectric conversion layer is embedded with a semiconductor having a wavelength shorter than the band gap or an equivalent band gap. With this configuration, the dark current is further reduced, the sensitivity is higher, and the afterimage is reduced more effectively.

  In the solid-state imaging device according to the aspect of the invention, it is preferable that a light-shielding film is provided on the photoelectric conversion unit except for a light-receiving surface. With this configuration, color mixing can be effectively prevented even when the solid-state imaging device (or photoelectric conversion unit) is arrayed.

  In the solid-state imaging device of the present invention, it is preferable that a microlens is provided on the light receiving surface of the photoelectric conversion unit. With this configuration, the light collection efficiency of light incident on the light receiving surface of the photoelectric conversion unit is improved.

  In the solid-state imaging device of the present invention, it is preferable that a color filter is provided on the light receiving surface of the photoelectric conversion unit. With this configuration, color separation can be performed.

The solid-state imaging system of the present invention includes the solid-state imaging device of the present invention, the photoelectric conversion unit is arrayed, and a color filter is provided on a light receiving surface of the photoelectric conversion unit,
The color filter has four colors, and the maximum values of the transmission are 420 to 480 nm (B), 480 to 520 nm (GB), 520 to 560 nm (G), and 580 to 620 nm (R),
Color reproduction is realized by taking an image with a photoelectric conversion unit that generates each color signal corresponding to the stimulus value of each primary color in the RGB color system, and performing an arithmetic process that adds a negative sensitivity component to these color signals. ,
An image is captured by a photoelectric conversion unit that generates a color signal corresponding to a spectral region (GB) of blue (B) and green (G) in the RGB color system, and the color signal generated by the photoelectric conversion unit is captured by the red color A new red (R ') color signal is formed by subtracting from the (R) color signal at a ratio based on a preset coefficient, and the new red (R') color signal is subjected to color mixing processing. It is characterized in that color reproduction is performed by applying it as a red color signal.

  In the solid-state imaging system of the present invention, color filters having a maximum value of transmission of 420 to 480 nm (B), 480 to 520 nm (GB), 520 to 560 nm (G), and 580 to 620 nm (R) are used. Perform red negative sensitivity correction to match the sensitivity. Using the color filter, the color signal output from the photoelectric conversion unit (light receiving element) corresponding to the three primary colors and the color signal obtained from the photoelectric conversion unit (light receiving element) corresponding to the negative sensitivity spectral region (GB) By performing the subtraction process, a color signal having a negative sensitivity characteristic is generated in a pseudo manner, so that the color reproduction region can be expanded as compared with the conventional color signal. When a luminance signal or a color difference signal is formed and an image is reproduced, a clear video can be expressed.

  According to the present invention, it is possible to provide a solid-state imaging device and a solid-state imaging system that have a high-quality photoelectric conversion layer, have high sensitivity, and have no afterimage.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that members having substantially the same function are denoted by the same reference numerals throughout the drawings.

(First embodiment)
FIG. 1 is a schematic configuration diagram illustrating a solid-state imaging device according to the first embodiment of the present invention. FIG. 2 is a process diagram showing a manufacturing process of the solid-state imaging device according to the first embodiment of the present invention.

  In the solid-state imaging device 10 according to this embodiment, a photoelectric conversion unit 14 is provided on a signal transfer circuit substrate 12 (semiconductor substrate) in which a signal transfer circuit (not shown) is formed on an Si substrate. Further, the photoelectric conversion unit 14 is sealed with an insulating sealing material 16 so as to cover the side surface thereof. Further, on the light receiving surface, a transparent insulating film 18 is provided on the uppermost layer of the photoelectric conversion unit 14 in order to protect the light receiving surface.

  The photoelectric conversion unit 14 includes a single-layer photoelectric conversion layer 20. The photoelectric conversion layer 20 is composed of, for example, a compound semiconductor layer made of GaAs. Specifically, the photoelectric conversion layer 20 includes an n-GaAs layer 20a, an i-GaAs layer 20b, and a p-GaAs layer 20c.

  The photoelectric conversion layer 20 is provided with an n-side electrode 22 and a p-side electrode 24 made of solder or the like. In order to make ohmic contact with the electrode, the n-side electrode 22 is provided on the photoelectric conversion layer 20 via the contact layer 26 made of n-GaAs, and the p-side electrode 24 is provided on the photoelectric conversion layer 20 via the contact layer 28 made of p-GaAs. Yes. The n-GaAs layer 20a also serves as the contact layer 26. Further, the p-GaAs layer 20 c also serves as the contact layer 28.

  The photoelectric conversion layer 20 is connected to the pixel electrode 30 formed on the signal transfer circuit substrate 12 via the n-side electrode 22 and joined to the common electrode 32 via the p-side electrode 24.

  In the photoelectric conversion layer 20, when light is incident on the light receiving surface, a signal (signal charge, signal current) is generated with respect to the incident light, and the signal is sent to the signal transfer circuit through the pixel electrode 30.

  The signal transfer circuit board 12 is composed of a silicon substrate, and a signal transfer circuit (not shown) is formed by a semiconductor process. Further, a pixel electrode 30 for sending a signal from the photoelectric conversion unit 14 to the signal transfer circuit is provided. A common electrode 32 is provided via an insulating layer 34.

  As the signal transfer circuit, a normal reading circuit can be used. The signal charge or signal current optically / electrically converted by the photoelectric conversion unit 14 (hereinafter referred to as the light receiving unit) is stored in the light receiving unit itself or an attached capacitor. The stored charge is read out together with the selection of the pixel position by using a so-called charge-coupled device (CCD) or a MOS type image pickup device (so-called CMOS sensor) using an XY address system. As a transfer readout method using a CCD, there is a method of having a charge transfer unit that transfers a charge signal of a pixel to an analog shift register by a transfer switch, and reading a signal according to an output terminal by the operation of the register. Examples include a line address type, a frame transfer type, an interline transfer type, and a frame interline transfer type method. In addition, the CCD has a two-phase structure, a three-phase structure, a four-phase structure, and a buried channel structure, but any structure can be applied.

  In addition, as an address selection method, there is a method in which each pixel is sequentially selected by a multiplexer switch and a digital shift register and read out as a signal voltage (or charge) on a common output line. An image sensor for XY address operation that is two-dimensionally arrayed is known as a CMOS sensor. This is because a switch connected to a pixel connected to the intersection of XY is connected to a vertical shift register, and when a switch is turned on by a voltage from the vertical scanning shift register, it is read from a pixel placed in the same row. The signal is read out to the output line in the column direction. This signal is read out from the output terminal in turn through a switch driven by a horizontal scanning shift register.

  For reading out the output signal, a floating diffusion detector or a floating gate detector can be used. Further, the S / N can be improved by providing a signal amplification circuit in the pixel portion or a correlated double sampling technique.

  For signal processing, gamma correction by an ADC circuit, digitization by an AD converter, luminance signal processing, and color signal signal processing can be performed. Examples of the color signal processing include white balance processing, color separation processing, and color matrix processing. When used for NTSC signals, RGB signals can be converted to YIQ signals.

  Hereinafter, a method for manufacturing the solid-state imaging device 10 according to the present embodiment will be described. The following compound semiconductor layers are stacked by, for example, metal organic vapor phase epitaxy or molecular beam epitaxy.

  First, as shown in FIG. 2A, a GaAs buffer layer 38 and an InGaP etching stop layer 40 are sequentially stacked on a GaAs substrate 36. Subsequently, an n-GaAs layer 20a (n-GaAs contact layer 26), an i-GaAs layer 20b, and a p-GaAs layer 20c (p-GaAs contact layer 28) are sequentially stacked. Then, Ti / Pt / Au is formed as the p-side electrode 24 on the p-GaAs contact layer 28 and patterned into a desired shape.

  In this manner, the photoelectric conversion unit 14 including the photoelectric conversion layer 20 including the n-GaAs layer 20a and the i-GaAs layer 20b is manufactured on the GaAs substrate 36.

  Next, as shown in FIG. 2B, a common electrode 32 having a predetermined pattern formed on a signal transfer circuit substrate 12 manufactured in a separate process using a GaAs substrate 36 provided with a photoelectric conversion unit 14. And the p-side electrode 24 are joined to dispose the photoelectric conversion unit 14. Thereafter, the GaAs substrate 36 and the GaAs buffer layer 38 are removed with an ammonia-based etchant. Then, the InGaP etching blocking layer 40 is removed with a hydrochloric acid-based etching solution to expose the n-GaAs layer 20a.

Next, as shown in FIG. 2C, AuGe / Ni / Au is formed as the n-side electrode 22 on the n-GaAs layer 20a. Then, three-dimensional structure formation of the photoelectric conversion layer 20 by dry etching, SiO ₂ lamination, via hole formation, via plug formation, etc. are performed as the sealing material 16, and the photoelectric conversion layer 20 in the photoelectric conversion unit 14 is connected via the n-side electrode 22. The pixel electrode 30 formed on the signal transfer circuit board 12 is connected. Thereafter, the transparent insulating film 18 is formed so as to protect the light receiving surface of the photoelectric conversion unit 14.

  In this way, the solid-state imaging device 10 according to this embodiment is manufactured.

  As described above, in the solid-state imaging device 10 according to the present embodiment described above, a compound semiconductor layer having good crystallinity and lattice matching is applied as the photoelectric conversion layer constituting the single-layer photoelectric conversion unit 14. The single-layer photoelectric conversion unit 14 moves charges at high speed, has little dark current, and is less likely to have defects, so that the area can be increased. For this reason, the solid-state image sensor 10 of this embodiment has high sensitivity and less afterimage. In addition, since the photoelectric conversion unit 14 can move charges at high speed, there is no problem of afterimage, and a high-quality image can be obtained even in high-speed driving such as digital video.

  In the solid-state imaging device 10 of the present embodiment, the photoelectric conversion layer 20 having a band gap in the infrared region has been configured as a GaAs layer. Instead, an InGaP layer lattice-matched to GaAs or the like is used. Alternatively, it may be composed of an InGaAsP layer. In particular, it is usually necessary to provide an infrared cut filter (not shown) in the solid-state imaging device 10, but if this photoelectric conversion layer 20 is formed of an InGaP layer, an infrared cut filter becomes unnecessary.

  In addition, the photoelectric conversion layer 20 may have a band gap in the visible to ultraviolet region, and can be composed of, for example, an InGaN layer, a GaN layer, or an AlGaN layer.

  In addition, the photoelectric conversion layer 20 may have a band gap in the infrared region, and may be formed of, for example, an InP layer, an InGaAs layer, or an InAlAs layer that lattice matches with InP.

  These compound semiconductor layers, for example, have higher crystallinity and perfect lattice matching than nitride-based compound semiconductors. It becomes the conversion unit 14.

  In the solid-state imaging device according to the present embodiment, since the photoelectric conversion unit 14 is provided on the signal transfer circuit board 12, the photoelectric conversion unit 14 is provided in the same plane as the signal transfer circuit provided on the signal transfer circuit board 12. Since the light receiving surface can be formed larger than in the case, the pixels can be miniaturized.

(Second Embodiment)
FIG. 3 is a schematic configuration diagram showing a solid-state imaging device according to the second embodiment of the present invention. FIG. 4 is a process diagram showing a manufacturing process of the solid-state imaging device according to the second embodiment of the present invention.

  In the solid-state imaging device according to this embodiment, the photoelectric conversion layer 20 (GaAs layer) constituting the photoelectric conversion unit 14 is embedded with an InGaP layer 42 having a wavelength shorter than or equal to the band gap of the GaAs layer. It is a form that is a structure. Here, the embedded structure means a structure in which the side surface of the photoelectric conversion layer 20 is covered with the semiconductor. Since the configuration other than this is the same as that of the first embodiment, the description thereof is omitted.

  Hereinafter, a method for manufacturing the solid-state imaging device 10 according to the present embodiment will be described. The following compound semiconductor layers are stacked by, for example, metal organic vapor phase epitaxy or molecular beam epitaxy.

  First, as shown in FIG. 4A, a GaAs buffer layer 38 and an InGaP etching blocking layer 40 are sequentially stacked on a GaAs substrate 36. Subsequently, an n-GaAs layer 20a, an i-GaAs layer 20b, and a p-GaAs contact layer 28 are sequentially stacked.

Next, as shown in FIG. 4B, a SiO ₂ layer (not shown) is formed on the p-GaAs contact layer 28, patterned into a desired shape, and this is used as a mask for normal lithography and dry etching. Thus, the periphery of the n-GaAs layer 20a, the i-GaAs layer 20b, and the p-GaAs contact layer 28 is removed. Then, the InGaP layer 42 is buried and grown by selective growth so as to cover the side surface of the layer. Thereafter, the SiO ₂ layer as a mask is removed, and Ti / Pt / Au is formed as the p-side electrode 24 on the p-GaAs contact layer 28 and patterned into a desired shape.

  In this manner, the photoelectric conversion unit 14 including the photoelectric conversion layer 20 including the n-GaAs layer 20a and the i-GaAs layer 20b embedded with the InGaP layer 42 on the GaAs substrate 36 is manufactured.

  Next, as shown in FIG. 4C, a common electrode 32 having a predetermined pattern formed on the signal transfer circuit substrate 12 manufactured in a separate process using the GaAs substrate 36 provided with the photoelectric conversion unit 14. And the p-side electrode 24 are joined to dispose the photoelectric conversion unit 14. Thereafter, the GaAs substrate 36 and the GaAs buffer layer 38 are removed with an ammonia-based etchant. Then, the InGaP etching blocking layer 40 is removed with a hydrochloric acid-based etching solution to expose the n-GaAs layer 20a.

Next, as shown in FIG. 4D, AuGe / Ni / Au is formed as the n-side electrode 22 on the n-GaAs layer 20a. Then, three-dimensional structure formation of the photoelectric conversion layer 20 by dry etching, SiO ₂ lamination, via hole formation, via plug formation, etc. are performed as the sealing material 16, and the photoelectric conversion layer 20 in the photoelectric conversion unit 14 is connected via the n-side electrode 22. The pixel electrode 30 formed on the signal transfer circuit board 12 is connected. Thereafter, the transparent insulating film 18 is formed so as to protect the light receiving surface of the photoelectric conversion unit 14.

  In this way, the solid-state imaging device 10 according to this embodiment is manufactured.

  As described above, in the solid-state imaging device according to the present embodiment described above, since the photoelectric conversion layer 20 is embedded with a semiconductor having a wavelength shorter than or equal to the band gap, the dark current can be further reduced and more effective. Really. Sensitivity is high and afterimage is reduced.

  In the present embodiment, the InGaP layer 42 is applied as a semiconductor having a wavelength shorter than or equal to the band gap of the photoelectric conversion layer 20 (GaAs layer). However, the present invention is not limited to this. It can be appropriately selected depending on the constituent material of the layer 20.

(Third embodiment)
FIG. 5 is a schematic configuration diagram showing a solid-state imaging device according to the third embodiment of the present invention.

  The solid-state imaging device 10 according to the present embodiment has a configuration in which a light shielding film 44 is provided on the photoelectric conversion unit 14 and is shielded from light except for the light receiving surface. The light shielding film 44 can be formed by, for example, applying a mask to the light receiving surface and depositing a metal material on the photoelectric conversion unit 14. Since the other configuration is the same as that of the first embodiment, the description thereof is omitted.

  In the solid-state imaging device 10 according to the present embodiment, when the solid-state imaging device 10 (or the photoelectric conversion unit 14) is arrayed by providing a light shielding film 44 on the photoelectric conversion unit 14 and shielding light other than the light receiving surface, It is possible to effectively prevent color mixing.

(Fourth embodiment)
FIG. 6 is a schematic configuration diagram showing a solid-state imaging device according to the fourth embodiment of the present invention.

  The solid-state imaging device 10 according to the present embodiment is a form in which a microlens 46 is provided on the light receiving surface of the photoelectric conversion unit 14. Since other than this is the same as in the first embodiment, the description is omitted.

  In the solid-state imaging device 10 according to the present embodiment, by providing the microlens 46 on the light receiving surface of the photoelectric conversion unit 14, the light collection efficiency of incident light is improved, and thus the sensitivity can be improved more effectively. .

(Fifth embodiment)
FIG. 7 is a schematic configuration diagram showing a solid-state imaging device according to the fifth embodiment of the present invention.

  The solid-state imaging device 10 according to the present embodiment has a configuration in which a color filter 48 is provided on the light receiving surface of the photoelectric conversion unit 14. Since other than this is the same as in the first embodiment, the description is omitted.

Here, FIG. 8 to FIG. 11 are plan views showing examples of the arrangement of the color filters 48 when the solid-state imaging device 10 (or the photoelectric conversion unit 14) is arrayed. FIG. 8 shows a case where a square color filter 48 with three colors is used. FIG. 9 shows a case where a hexagonal color filter 48 with three colors is used. FIG. 10 shows a case where a square color filter 48 with four colors is used. FIG. 11 shows a case where a hexagonal color filter 48 with four colors is used. In the figure, B is blue having a spectral sensitivity maximum in the range of 420 to 480 nm, and G ₂ is an emerald clean having a spectral maximum in the range of 480 to 520 nm. Blue (B) and green (G) corresponding to the spectral region (GB) of the intermediate color), G ₁ is the green whose transmission maximum is in the range of 520 to 560 nm, R is the transmission maximum A red color filter 48 having a maximum spectral sensitivity in the range of 580 to 620 nm is shown. A photoelectric conversion unit 14 (solid-state imaging device 10) having a shape similar to that of the color filter 48 is provided below these color filters 48.

  Thus, in the solid-state imaging device 10 according to the present embodiment, when arrayed, by providing the color filters 48 of a plurality of colors on the light receiving surface of the photoelectric conversion unit 14, for example, a three-color separation structure or four colors A separation structure is possible.

(Sixth embodiment)
The solid-state imaging system according to the present embodiment has a configuration in which the solid-state imaging device 10 according to the above-described embodiment is arrayed (the photoelectric conversion unit 14 is arrayed) and four color filters are provided. In the present embodiment, the photoelectric conversion unit 14 provided with the four color filters is referred to as a light receiving element (see FIGS. 10 and 11 for the arrangement of the color filters).

The solid-state imaging system according to the present embodiment is a system for imaging with a charge coupled solid-state imaging device (CCD), and is a light receiving unit (photoelectric conversion unit 14) in which a large number of light receiving elements are arranged in a matrix. For example, light receiving elements for a total of 800,000 pixels, which are 1000 rows in the vertical scanning direction and 800 columns in the horizontal scanning direction, are provided. These light receiving elements include, for example, a first row in which two types of fine filters G ₁ and G ₂ for alternately generating a green color signal are provided, and a fine line for generating red and blue color signals. Second rows in which the filters R and B are alternately provided are alternately formed and arranged in the vertical scanning direction. These arrangement directions indicate diagonal directions in the case of a rectangular color filter, and opposite directions in the case of a hexagonal color filter.

Here, as shown in the fifth embodiment, the green filter G ₁ has the maximum spectral sensitivity in the range of about 520 nm to 560 nm, while the emerald green filter G ₂ has the range of about 480 nm to 520 nm. The red filter R has a spectral sensitivity maximum in the range of about 580 nm to 620 nm, and the blue filter B has a spectral sensitivity maximum in the range of about 420 nm to 480 nm. In addition, the sensitivity region of the emerald green filter G ₂ is set to be approximately equal to the red negative sensitivity region (see FIG. 12), and the spectral characteristics of the filters G ₂ and G ₁ are combined to have a wavelength range of about 460 nm to 640 nm. Designed to have spectral characteristics.

The signals (signal charges and signal currents) generated from each of the light receiving elements are simultaneously subjected to vertical scanning reading with a pair of signal charges generated in the light receiving elements in the first and second rows that are adjacent to each other. The signal charges for green (G ₁ ) and emerald green (G ₂ ) in the first row are read out through the horizontal charge transfer path, and the signal charges for red (R) and blue (B) in the second row Are read out through the horizontal charge transfer path.

Each signal read out through the horizontal charge transfer path is switched in synchronism with the period of the dot order by multiplex sag, thereby separating each color signal. For the red second row (R) and blue (B), the color signal S _B of the red color signals S _R and blue separated, the first row of green (G ₁₎ and emerald green (G ₂ ), The green color signal S _G1 and the emerald green color signal S _G2 are separated.

Then, in the arithmetic circuit, a new sensitivity that compensates for the negative sensitivity component is obtained by performing the following formulas (1) to (3) based on the separated color signals S _R , S _B , S _G1 , S _G2. Red (R '), blue (B') and green (G ') color signals. That is, S _R (t), S _B (t), S _G1 (t), S _G2 (t) are output from the multiplexer in synchronization with a predetermined timing, and R ′ (t) is a new color signal. , B ′ (t), G ′ (t)
G ′ (t) = S _G1 (t) + k ₁ × S _G2 (t) − {k ₂ × S _B (t) + k ₃ × S _R (t)} (1)
R ′ (t) = S _R (t) − [k ₄ × S _G2 (t) −k ₇ × S _B (t)] (2)
B ′ (t) = S _B (t) − [k ₅ × S _G1 (t) + k ₆ × S _R (t)] (3)
It becomes.

In the equation, k _{1 to} k ₇ are coefficients set in advance by experiments or the like, and are adjusted so as to obtain color signals R ′ (t), B ′ (t), G ′ (t) that are close to actual values. It is decided.

Here, in FIG. 12, a color matching function representing an ideal spectral characteristic of the color filter, the horizontal axis is wavelength and the vertical axis represents the stimulus value (lumen), the ideal solid F _R is a red filter in FIG. spectroscopic properties, ideal spectral characteristics of the broken line F _G green filter, the dotted line F _B shows the ideal spectral characteristic of the blue filter. These negative stimulus values (negative sensitivity components) are indicated by hatched portions α, β, γ, and δ.

With respect to this ideal spectral characteristic, according to the above equation (1), the ideal spectral characteristic includes an negative sensitivity component α in the range of about 400 nm to 460 nm and a negative sensitivity component δ in the range of about 640 nm to 680 nm in FIG. close green signal (see dashed F _G in FIG. 12) can be artificially formed.

Further, according to the above equation (2), a red signal close to ideal including the negative sensitivity component β in the range of about 460 nm to 530 nm and the positive sensitivity component ε in the range of 420 to 400 nm in FIG. can form a reference to the solid line F _R).

Further, according to the equation (3) to form a negative sensitivity component γ laden near ideal blue signals in the range of about 530Nm～620nm (see dotted line F _B in FIG. 12) in FIG. 12.

  That is, the color signals R ′ (t), B ′ (t), G ′ (t) formed by the above formulas (1) to (3) approach the ideal spectral characteristics shown in FIG. The three primary colors (R), (G), and (B) are approached, and the color reproducible region is enlarged.

  Then, based on these new color signals R ′ (t), B ′ (t), G ′ (t), for example, luminance signals and color difference signals conforming to the standard television system are formed, and the image is reproduced on the monitor. As a result, a clear reproduced image can be obtained as compared with the conventional case.

  Thus, in the solid-state imaging system according to the present embodiment, a light receiving element (photoelectric conversion unit 14 provided with an emerald green color filter in the present embodiment) having a spectral sensitivity with respect to at least the wavelength of the red negative sensitivity region is provided, The color signal output from the light receiving element is subtracted from at least a predetermined ratio from the red color signal to form a new red (R ′) color signal, and the new red (R ′) color signal is converted into the new red (R ′) color signal. Since color reproduction is performed by applying it as a red color signal in color mixing processing, it is possible to reproduce intermediate colors that could not be reproduced in the past, resulting in a more natural and clear reproduction image. can get.

  Note that the detailed principle and operation of the solid-state imaging system according to this embodiment is described in Japanese Patent No. 2872759, and other embodiments can be implemented in accordance with the specification.

  It should be noted that any of the above embodiments can be implemented in combination. In addition, in any of the above-described embodiments, it is needless to say that the present invention is not interpreted in a limited manner and can be realized within the range satisfying the requirements of the present invention.

1 is a schematic configuration diagram illustrating a solid-state imaging element according to a first embodiment of the present invention. It is process drawing which shows the manufacture process of the solid-state image sensor which concerns on 1st Embodiment of this invention. It is a schematic block diagram which shows the solid-state image sensor which concerns on 2nd Embodiment of this invention. It is process drawing which shows the manufacture process of the solid-state image sensor which concerns on 2nd Embodiment of this invention. It is a schematic block diagram which shows the solid-state image sensor which concerns on 3rd Embodiment of this invention. It is a schematic block diagram which shows the solid-state image sensor which concerns on 4th Embodiment of this invention. It is a schematic block diagram which shows the solid-state image sensor which concerns on 5th Embodiment of this invention. It is a top view which shows the example of an arrangement | sequence of the color filter in the solid-state image sensor which concerns on 5th Embodiment of this invention. It is a top view which shows the example of an arrangement | sequence of the color filter in the solid-state image sensor which concerns on 5th Embodiment of this invention. It is a top view which shows the example of an arrangement | sequence of the color filter in the solid-state image sensor which concerns on 5th Embodiment of this invention. It is a top view which shows the example of an arrangement | sequence of the color filter in the solid-state image sensor which concerns on 5th Embodiment of this invention. It is a figure of a color matching function which shows the ideal spectral characteristic of a color filter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Solid-state image sensor 12 Signal transfer circuit board 14 Photoelectric conversion part 16 Sealing material 18 Transparent insulating film 20 Photoelectric conversion layer 22 n side electrode 24 p side electrode 26 Contact layer 28 Contact layer 30 Pixel electrode 32 Common electrode 34 Insulating layer

Claims (9)

A photoelectric conversion unit that generates a signal by incident light from outside;
A semiconductor substrate provided with a signal transfer circuit for reading the signal generated from the photoelectric conversion unit, the photoelectric conversion unit being provided on the surface;
In a solid-state imaging device having
The photoelectric conversion layer which comprises the said photoelectric conversion part is comprised by the single layer structure of the compound semiconductor layer, The solid-state image sensor characterized by the above-mentioned. The semiconductor substrate comprises a silicon substrate;
The solid-state imaging device according to claim 1, wherein the light conversion layer includes a GaAs layer, an InGaP layer, or an InGaAsP layer lattice-matched to GaAs. The semiconductor substrate comprises a silicon substrate;
The solid-state imaging device according to claim 1, wherein the light conversion layer includes an InP layer, an InGaAs layer, and an InAlAs layer that lattice-match with InP.   The solid-state imaging device according to claim 1, wherein the photoelectric conversion layer is embedded with a semiconductor having a shorter wavelength than the band gap or an equivalent band gap.   The solid-state imaging device according to claim 1, wherein a light-shielding film is provided on the photoelectric conversion unit except for a light-receiving surface.   The solid-state imaging device according to claim 1, wherein a microlens is provided on a light receiving surface of the photoelectric conversion unit.   The solid-state imaging device according to claim 1, wherein a color filter is provided on a light receiving surface of the photoelectric conversion unit. A solid-state imaging system comprising the solid-state imaging device according to any one of claims 1 to 6, wherein the photoelectric conversion unit is arrayed, and a color filter is provided on a light receiving surface of the photoelectric conversion unit,
The color filter consists of four colors, and the maximum values of the transmission are 420 to 480 nm (B), 480 to 520 nm (GB), 520 to 560 nm (G), and 580 to 620 nm (R),
Color reproduction is realized by taking an image with a photoelectric conversion unit that generates each color signal corresponding to the stimulus value of each primary color in the RGB color system, and performing an arithmetic process that adds a negative sensitivity component to these color signals. ,
An image is captured by a photoelectric conversion unit that generates a color signal corresponding to a spectral region (GB) of blue (B) and green (G) in the RGB color system, and the color signal generated by the photoelectric conversion unit is captured by the red color A new red (R ') color signal is formed by subtracting from the (R) color signal at a ratio based on a preset coefficient, and the new red (R') color signal is subjected to color mixing processing. A solid-state imaging system that reproduces color by applying it as a red color signal. The semiconductor substrate comprises a silicon substrate;
The solid-state imaging device according to claim 1, wherein the light conversion layer includes an InGaN layer, a GaN layer, or an AlGaN layer.

Images