JP5332572B2 - Solid-state imaging device and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state image sensing device high in light use efficiency and improved in sensitivity, and electronic equipment using the solid-state image sensing device. <P>SOLUTION: The solid-state image sensing device has a picture element 3 which is constituted by laminating semiconductor chips 10b, 10g, 10r having photosensitive sensors 4b, 4g, 4r for generating and storing signal charges by receiving light in substrates 12b, 12g, 12r. The plurality of semiconductor chips 10 constituting the picture element 3 generate and store the signal charges according to light Lb, Lg, Lr having different wavelengths. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a solid-state imaging device and an electronic apparatus including the solid-state imaging device.

Conventionally, CCD and CMOS type solid-state imaging devices are known as solid-state imaging devices.
Color spectroscopy in a CCD solid-state imaging device (CCD image sensor) or a CMOS solid-state imaging device (CMOS image sensor) is realized mainly by using a color filter. In an image sensor using a color filter, one type of color filter is mounted on one pixel, and three pixel circuits mainly having red, green, and blue color filters are arranged next to each other. In an image sensor using such a color filter, color generation is performed by using information on light incident on adjacent pixels on which color filters of different colors are mounted. Therefore, in an image sensor using a color filter, a false color is generated in which a color generated in an arbitrary pixel is different from a color of light actually incident on the pixel.

  In addition, in an image sensor using a color filter in this manner, light that can be received by one pixel is strictly one color corresponding to the color filter, and only one third of the light can be used. Therefore, the light utilization efficiency is poor and the sensitivity is low. Further, since two-thirds of the light is absorbed by the color filter, the product life may be affected depending on the light resistance of the color filter.

  Therefore, in order to efficiently use the amount of incident light, a method of performing spectroscopy by forming a plurality of photodiodes in the depth direction in the substrate in one pixel has been developed.

  In Patent Document 1, for example, as shown in FIG. 13, a three-layer structure of an n-type semiconductor layer 102 / p-type semiconductor layer 104 / n-type semiconductor layer 106 is formed in a p-type Si substrate 100, A color separation method is described in which blue, green, and red light are photoelectrically converted and extracted from the shallower side. In this method, on the surface of the Si substrate 100, blue, green, and red signals are output to the outside by the respective terminals connected to the respective layers. This utilizes the wavelength length and the light absorption property in the depth direction. As a result, color separation can be performed in one pixel. Further, since no color filter is used, colors having different wavelengths of red, green, and blue enter the unit pixel. For this reason, the loss of light quantity is also reduced.

  However, in the configuration shown in FIG. 13, since all color separation is performed in the bulk, there is a problem that the degree of freedom in structural design is low and color mixing is unavoidable. There are also disadvantages in that it is difficult to form a potential in the bulk and it is difficult to extract signal charges.

  On the other hand, Patent Document 2 describes a solid-state imaging device having a light receiving unit in which photoelectric conversion films are stacked in a plurality of stages. When a photoelectric conversion film is used, charges are accumulated in the film. Therefore, when the charges are read, the charges remain, and an afterimage is likely to occur in principle. In Patent Document 2, three layers of photoelectric conversion films are sequentially stacked on a semiconductor substrate, and signals for each of R (red), G (green), and B (blue) generated in each photoelectric conversion film are obtained. It is necessary to form vertical wirings connected to signal readout circuits formed on the semiconductor substrate. For this reason, there is a problem that the manufacturing is difficult and the manufacturing yield is low, so that the cost is high.

Patent Document 3 describes a solid-state imaging device having a light receiving unit in which photoelectric conversion films and color filters are alternately stacked. In this case as well, since charges are accumulated in the photoelectric conversion film as described above, charges are likely to remain and an afterimage is likely to occur when reading charges.
JP-T-2002-513145 JP 2004-335626 A JP-A-2005-347386

  In view of the above, the present invention provides a solid-state imaging device with high light utilization efficiency and improved sensitivity. In addition, the present invention provides an electronic device using the solid-state imaging device.

In order to solve the above-described problems and achieve the object of the present invention, a solid-state imaging device of the present invention has a semiconductor chip having a light-receiving sensor portion in a substrate that receives light and generates and accumulates signal charges at a predetermined interval. and has a pixel portion of the stacked configurations have. The plurality of semiconductor chips constituting the pixel portion generate and accumulate signal charges according to light of different wavelengths. Each semiconductor chip has an output unit that reads and outputs the signal charges accumulated in the light receiving sensor unit. Furthermore, the thickness of the substrate constituting each semiconductor chip is the thinnest among the semiconductor chips arranged on the light incident side among the plurality of stages of semiconductor chips constituting the pixel portion. It is formed thickest in the semiconductor chip arranged on the opposite side.

  In the solid-state imaging device according to the present invention, the pixel unit is configured by stacking a plurality of semiconductor chips capable of generating and storing signal charges according to different light, so that one pixel corresponds to a plurality of colors. Light is absorbed and photoelectrically converted. In each semiconductor chip, signal charges corresponding to light of different wavelengths are generated and stored. Thereby, color mixing is reduced.

The electronic apparatus according to the present invention includes an optical lens, a solid-state imaging device, and a signal processing circuit. This solid-state imaging device is the above-described solid-state imaging device of the present invention.

  In the electronic apparatus of the present invention, in the solid-state imaging device, the pixel portion is configured by stacking a plurality of semiconductor chips that can generate and accumulate signal charges according to different lights. Signal charges corresponding to a plurality of colors of light are generated, thereby obtaining an image.

  According to the present invention, it is possible to obtain a solid-state imaging device and an electronic apparatus in which sensitivity is improved and afterimage is reduced.

Hereinafter, an example of a solid-state imaging device, a manufacturing method thereof, and an electronic apparatus according to an embodiment of the present invention will be described with reference to FIGS. Embodiments of the present invention will be described in the following order. In addition, this invention is not limited to the following examples.
1. 1. Overall configuration example of solid-state imaging device (CCD type) First Embodiment: Basic Configuration Example 3. 2. Second embodiment: Example using color filter 3. Third embodiment: Example using color filter and support layer Fourth embodiment: Example using a support layer also serving as a color filter 6. Fifth Embodiment: Example in which the thickness of the substrate is different between the light receiving portion and the charge transfer portion in the semiconductor chip. Sixth Embodiment: Example of directly bonding adjacent semiconductor chips 8. 7. Seventh Embodiment: Example applied to a CMOS type solid-state imaging device Eighth embodiment: electronic device (camera)

<1. Example of overall configuration of solid-state imaging device (CCD type)>
First, FIG. 1 shows an overall configuration of a CCD type solid-state imaging device, which is a configuration common to the following first to sixth embodiments.

  As shown in FIG. 1, a CCD solid-state imaging device 1 includes a plurality of light receiving sensor units 4 formed in a horizontal direction and a vertical direction, a vertical transfer register 5 having a CCD structure, and a horizontal transfer register 6 having a CCD structure. And an output circuit 8.

The light receiving sensor unit 4 includes a photoelectric conversion element, that is, a photodiode, and generates and accumulates signal charges according to the amount of received light.
A plurality of vertical transfer registers 5 are formed for each column in common with the light receiving sensor units 4 arranged in the vertical direction, and the signal charges accumulated in the light receiving sensor units 4 are read out in the vertical direction. To be transferred.

  Each pixel 7 includes each light receiving sensor unit 4 and a part of the vertical transfer register 5 adjacent to the light receiving sensor unit 4. A region where the pixels 7 are formed in a matrix in the horizontal direction and the vertical direction is the pixel unit 3. The pixel unit 3 includes an effective pixel region for receiving light and outputting a signal, and an invalid pixel region for optical black (OPB: Optical Black) that serves as a reference for the black level. Although not shown, the invalid pixel region is formed around the effective pixel region.

  The horizontal transfer register 6 is formed, for example, at one end of the vertical transfer register 5 and transfers the signal charge vertically transferred by the vertical transfer register 5 for each horizontal line.

  The output circuit 8 outputs the signal charge horizontally transferred by the horizontal transfer register 6 as a pixel signal by charge-voltage conversion.

  In the first to sixth embodiments described below, a cross-sectional configuration of the pixel unit 3 of the solid-state imaging device will be described.

<2. First Embodiment: Basic Configuration Example>
[Cross section configuration]
2A is a schematic perspective view of one pixel of the solid-state imaging device according to the first embodiment of the present invention, and FIG. 2B is a schematic cross-sectional configuration diagram of one pixel.

As shown in FIG. 2A, the pixel unit 3 of the solid-state imaging device according to the present embodiment includes a plurality of semiconductor chips 10 stacked in a plurality of stages (three stages in the present embodiment), and the plurality of semiconductor chips 10. Connection pads 9 are connected to each other.
In this embodiment, each semiconductor chip 10 constituting the pixel unit 3 will be described as a first semiconductor chip 10b, a second semiconductor chip 10g, and a third semiconductor chip 10r in order from the light incident side. The first semiconductor chip 10b, the second semiconductor chip 10g, and the third semiconductor chip 10r will be described as the semiconductor chip 10 unless they are particularly distinguished.

  As shown in FIG. 2B, the first semiconductor chip 10b includes a light receiving sensor unit 4b formed in the substrate 12b, and a vertical transfer register 5b serving as an output unit that reads and outputs the signal charges accumulated in the light receiving sensor unit 4b. And is configured. The second semiconductor chip 10g includes a light receiving sensor unit 4g formed in the substrate 12g, and a vertical transfer register 5g serving as an output unit that reads out and outputs signal charges accumulated in the light receiving sensor unit 4g. Yes. The third semiconductor chip 10r includes a light receiving sensor unit 4r formed in the substrate 12r, and a vertical transfer register 5r serving as an output unit that reads and outputs the signal charges accumulated in the light receiving sensor unit 4r. Yes.

  The connection pad 9 is made of a conductive material. By the connection pads 9, the first semiconductor chip 10b, the second semiconductor chip 10g, and the third semiconductor chip 10r are stacked vertically and supported for connection. In the embodiment, the first semiconductor chip 10b, the second semiconductor chip 10g, and the third semiconductor chip 10r are stacked with a predetermined distance from the adjacent semiconductor chip 10, respectively.

  3A to 3C show detailed cross-sectional configurations of the first semiconductor chip 10b, the second semiconductor chip 10g, and the third semiconductor chip 10r of the present embodiment example.

First, the semiconductor chip 10b will be described with reference to FIG. 3A.
As shown in FIG. 3A, the substrate 12b is composed of a first conductivity type, for example, an n-type silicon substrate. A p-type semiconductor well region 13 made of a second conductivity type, for example, a p-type impurity region is formed on the back surface side of the substrate 12b.

The light receiving sensor unit 4 includes a hole accumulation region 15 made of a p-type high concentration impurity region (p +) formed on the surface of the substrate 12b, a charge accumulation region 14 made of an n-type impurity region (n), and a p-type. The photodiode is composed of a semiconductor well region 13. The hole accumulation region 15 is formed on the outermost surface of the substrate 12 on the light incident side. The charge storage region 14 is formed from just below the hole storage region 15 to a depth reaching the p-type semiconductor well region 13.
In the present embodiment, the photodiode serving as the light receiving sensor portion 4b is mainly constituted by a pn junction j formed at the interface between the charge storage region 14 and the p-type semiconductor well region 13. The light incident on the light receiving sensor unit 4b is photoelectrically converted by the photodiode, thereby generating a signal charge. Then, the generated signal charge is accumulated in the charge accumulation region 14 composed of an n-type impurity region.

The vertical transfer register 5 b serving as an output unit includes a reading unit 18, a vertical transfer channel 17, and a transfer electrode 16.
The reading unit 18 is made of a p-type impurity region, and is in contact with the charge accumulation region 14 constituting the light receiving sensor unit 4 on the surface side of the substrate 12 on one side of the light receiving sensor unit 4 (left side in FIG. 3A). It is formed as follows.
The vertical transfer channel 17 is made of an n-type impurity region, and is formed on the surface side of the substrate 12 adjacent to the readout unit 18.
The transfer electrode 16 is formed on the substrate 12 on which the readout unit 18 and the vertical transfer channel 17 are formed via the insulating film 11.

  Next, the semiconductor chip 10g will be described with reference to FIG. 3B. In FIG. 3B, parts corresponding to those in FIG.

  As shown in FIG. 3B, the substrate 12g is composed of a first conductivity type, for example, an n-type silicon substrate. A p-type semiconductor well region 13 made of a second conductivity type, for example, a p-type impurity region, is formed on the back side of the substrate 12g.

The light receiving sensor unit 4g includes a hole accumulation region 15 made of a p-type high concentration impurity region (p +) formed on the surface of the substrate 12g, a charge accumulation region 14 made of an n-type impurity region (n), and a p-type. The photodiode is composed of a semiconductor well region 13. The hole accumulation region 15 is formed on the outermost surface of the substrate 12 on the light incident side. The charge storage region 14 is formed from just below the hole storage region 15 to a depth reaching the p-type semiconductor well region 13.
In the present embodiment, the photodiode serving as the light receiving sensor portion 4g is mainly constituted by a pn junction j formed at the interface between the charge storage region 14 and the p-type semiconductor well region 13. The light incident on the light receiving sensor unit 4g is photoelectrically converted by the photodiode, thereby generating a signal charge. Then, the generated signal charge is accumulated in the charge accumulation region 14 composed of an n-type impurity region.

  The vertical transfer register 5g serving as an output unit has the same configuration as the vertical transfer register 5b.

  Next, the semiconductor chip 10r will be described with reference to FIG. 3C. In FIG. 3C, parts corresponding to those in FIG.

  As shown in FIG. 3C, the substrate 12r is composed of a first conductivity type, for example, an n-type silicon substrate. A p-type semiconductor well region 13 made of a second conductivity type, for example, a p-type impurity region is formed at a desired depth of the substrate 12r.

The light receiving sensor unit 4r includes a hole accumulation region 15 made of a p-type high concentration impurity region (p +) formed on the surface of the substrate 12r, a charge accumulation region 14 made of an n-type impurity region (n), and a p-type. The photodiode is composed of a semiconductor well region 13. The hole accumulation region 15 is formed on the outermost surface of the substrate 12 on the light incident side. The charge storage region 14 is formed from just below the hole storage region 15 to a depth reaching the p-type semiconductor well region 13.
In the present embodiment, the photodiode serving as the light receiving sensor portion 4r is mainly constituted by a pn junction j formed at the interface between the charge storage region 14 and the p-type semiconductor well region 13. The light incident on the light receiving sensor unit 4r is photoelectrically converted by the photodiode, thereby generating a signal charge. Then, the generated signal charge is accumulated in the charge accumulation region 14 composed of an n-type impurity region.

  The vertical transfer register 5r serving as an output unit has the same configuration as the vertical transfer register 5b.

  Incidentally, the wavelength dependence of the absorption length of light absorbed by silicon has the relationship shown in FIG. The horizontal axis in FIG. 4 is the wavelength (nm), and the vertical axis is the silicon thickness (μm) necessary for light absorption. As can be seen from FIG. 4, in order to absorb 70% or more of blue light having a wavelength of 450 nm, a silicon thickness of 0.6 μm or more is required. Further, in order to absorb 70% or more of green light having a wavelength of 550 nm, a silicon thickness of 1.7 μm or more is required. Further, in order to absorb 70% or more of red light having a wavelength of 650 nm, a silicon thickness of 3.7 μm or more is required.

In this embodiment, the light receiving sensor portion 4b of the first semiconductor chip 10b absorbs about 70% of the blue (B) light Lb, so that the thickness of the substrate 12b is about 0.6 μm. When the thickness of the substrate 12b is clearly thinner than 0.6 μm, blue light is not absorbed, and when the thickness is clearly thicker than 0.6 μm, green light and red light are not absorbed. Will also be absorbed. In addition, since the light incident on the light receiving sensor unit 4b is photoelectrically converted in the vicinity of the pn junction constituting the photodiode, the pn junction depth is preferably formed to a depth corresponding to the thickness of the substrate 12b.
In addition, in the light receiving sensor portion 4g of the second semiconductor chip 10g, the thickness of the substrate 12g is set to about 1.7 μm in order to absorb about 70% of the green (G) light Lg. If the thickness of the substrate 12g is clearly thinner than 1.7 μm, green light is not absorbed, and if it is clearly thicker than 1.7 μm, even red light is absorbed. It will be. In addition, since the light incident on the light receiving sensor unit 4g is photoelectrically converted in the vicinity of the pn junction constituting the photodiode, the pn junction depth is preferably formed to a depth corresponding to the thickness of the substrate 12g.
Further, in order to absorb about 70% of the red (R) light Lr in the light receiving sensor part 4r of the third semiconductor chip 10r, the thickness from the surface of the substrate 12r to the pn junction j is set to about 3.7 μm. When the thickness from the surface of the substrate 12r to the pn junction j is clearly thinner than 3.7 μm, red light is not absorbed. In the first semiconductor chip 10b and the second semiconductor chip 10g, it is necessary to transmit light having a wavelength that is not photoelectrically converted by the light receiving sensor portions 4b and 4r. Therefore, it is necessary to adjust the thickness of the substrates 12b and 12g themselves. However, in the third semiconductor chip 10r, since the light having the longest wavelength is photoelectrically converted in the light receiving sensor unit 4r and it is not necessary to transmit light, the thickness of the substrate 12r is the same as that of the light receiving sensor unit. The thickness can be the same as that of a conventional semiconductor chip. That is, the thickness of the substrate 12r can be formed to be thicker than 3.7 μm, and the signal charge overflowing from the charge storage region 14 is overflowed to the substrate 12r side beyond the p-type semiconductor well region 13. be able to.

  The first semiconductor chip 10b, the second semiconductor chip 10g, and the third semiconductor chip 10r having the above configuration are stacked at a predetermined interval and connected and supported by connection pads, whereby the pixel unit 3 is configured. ing.

  In FIG. 2, the semiconductor chip for one pixel has been described. By the way, in the pixel unit 3 of the actual solid-state imaging device, as shown in FIG. 5, each stacked semiconductor chip 10 includes a plurality of light receiving sensor units 4 formed in the vertical direction and the horizontal direction of the substrate 12 and receives light. A plurality of vertical transfer registers 5 (output units) formed for each column of the sensor units 4 are provided. In this case, the vertical transfer channel 17 constituting the vertical transfer register 5 shown in FIG. 3B is formed for each column of the light receiving sensor units 4 formed in the vertical direction. The semiconductor chip 10 on which the plurality of light receiving sensor portions 4 are formed is stacked with a predetermined distance from the adjacent semiconductor chip 10 and is connected and supported by the connection pad 9 at the end.

[Operation]
The operation of the solid-state imaging device having the above configuration will be described with reference to FIGS.

  First, as shown in FIG. 2B, light enters from the first semiconductor chip 10 b side of the pixel unit 3. In the first semiconductor chip 10b, the photodiode constituting the light receiving sensor unit 4b is formed at a depth of the substrate 12b where the blue light Lb is absorbed. For this reason, among the light incident from the first semiconductor chip 10b side, the blue light Lb is absorbed and photoelectrically converted by the light receiving sensor unit 4b formed in the first semiconductor chip 10b. For this reason, in the light receiving sensor unit 4b of the first semiconductor chip 10b, signal charges corresponding to the light Lb having a blue wavelength are generated and accumulated. And the light which was not absorbed in the light receiving sensor part 4b, ie, lights other than the blue light Lb, permeate | transmits the 1st semiconductor chip 10b, and injects into the light receiving sensor part 4g of the 2nd semiconductor chip 10g.

  In the second semiconductor chip 10g, the photodiode constituting the light receiving sensor unit 4g is formed at a depth of the substrate 12g where the green wavelength light Lg is absorbed. Further, since the light incident on the light receiving sensor portion 4g of the second semiconductor chip 10g is transmitted through the light receiving sensor portion 4b of the first semiconductor chip 10b, the blue wavelength light Lb is already separated. For this reason, in the light receiving sensor portion 4g of the second semiconductor chip 10g, signal charges corresponding to the green wavelength light Lg are generated and accumulated. And the light which was not absorbed in the light receiving sensor part 4g permeate | transmits the 2nd semiconductor chip 10g, and injects into the light receiving sensor part 4r of the 3rd semiconductor chip 10r.

  In the third semiconductor chip 10r, the photodiode constituting the light receiving sensor unit 4r is formed at a depth of the substrate 12r where the light Lr having a red wavelength is absorbed. Further, the light incident on the light receiving sensor unit 4r of the third semiconductor chip 10r is transmitted through the light receiving sensor unit 4b of the first semiconductor chip 10b and the light receiving sensor unit 4g of the second semiconductor chip 10g. Light Lb and green wavelength light Lg are already separated. For this reason, in the light receiving sensor unit 4g of the third semiconductor chip 10r, signal charges corresponding to the red wavelength light Lr are generated and accumulated.

  Here, the connection pad 9 is made of a conductive material, and a constant voltage is applied during operation. As a result, the first semiconductor chip 10b, the second semiconductor chip 10g, and the third semiconductor chip 10r are stably held at a constant voltage. In other words, each semiconductor chip 10 can be held at a constant voltage even when the signal charge overflowing in the light receiving sensor portion 4 of each semiconductor chip 10 overflows to the n-type semiconductor region side of the substrate 12.

In the first semiconductor chip 10b, the second semiconductor chip 10g, and the third semiconductor chip 10r, the signal charges corresponding to RGB accumulated in the light receiving sensor units 4b, 4g, and 4r are transmitted by the vertical transfer registers 5b, 5g, and 5r. , Transferred in the vertical direction.
At this time, in each vertical transfer register 5, by applying a predetermined voltage to the transfer electrode 16 shown in FIG. 3, the signal charge accumulated in the light receiving sensor unit 4 is read out to the vertical transfer channel 17 through the reading unit 18. It is. Then, signal charges are transferred in the vertical direction by applying, for example, a four-phase drive pulse to the transfer electrodes 16 formed in the row direction of the light receiving sensor unit 4.

  In the solid-state imaging device according to this embodiment, the signal charges transferred by the vertical transfer register 5 for each semiconductor chip 10 are transferred in the horizontal direction by the horizontal transfer register 6 as shown in FIG. Is output as a pixel signal.

  According to the solid-state imaging device of the present embodiment, the first semiconductor chip 10b, the second semiconductor chip 10g, and the third semiconductor chip 10r are stacked in the order in which light having a short wavelength is absorbed from the light incident side. Thus, signal charges corresponding to the three colors of RGB light can be obtained. That is, by vertically stacking three layers of semiconductor chips 10 corresponding to RGB, the light use efficiency per pixel is three times higher than that of a pixel that performs spectroscopy using a conventional color filter. For this reason, the sensitivity is improved.

  In addition, according to the solid-state imaging device of the present embodiment example, it is possible to obtain signal charges corresponding to all RGB light with one pixel, so that it is not necessary to complement other colors, and in principle Does not generate false colors.

  Further, in the conventional solid-state imaging device using the organic photoelectric conversion film, there is a problem that the organic photoelectric conversion film is deteriorated by light. However, according to the solid-state imaging device of this embodiment, each semiconductor chip 10 Since it is constituted by the substrate 12 made of silicon, the light resistance can be improved.

  In addition, in a conventional solid-state imaging device using a photoelectric conversion film, signal charges are accumulated in the photoelectric conversion film, so that signal charges remain in the film during reading, and an afterimage is generated in principle. According to the solid-state imaging device of the present embodiment example, the signal charges generated and accumulated in each semiconductor chip 10 can be transferred by the normal vertical transfer register 5 that transfers according to the fluctuation of the potential in the substrate 12. As a result, it is possible to suppress the generation of residual charges at the time of reading signal charges and to suppress the afterimage.

  In addition, in the configuration in which three layers of photodiodes are formed in one substrate and color separation is performed in one substrate as in the conventional solid-state imaging device shown in the figure, the saturation charge amount is limited. Also, there is a problem that it is difficult to take out signal charges. According to the solid-state imaging device of the present embodiment example, the photodiode formed in one substrate 12 constituting each semiconductor chip 10 photoelectrically converts only light of one color wavelength. In this case, the saturation charge amount can be improved.

  In the solid-state imaging device according to this embodiment, the signal charge accumulated in the light receiving sensor unit is read and transferred by a vertical transfer register that is an output unit formed in the same substrate as the substrate on which the light receiving sensor unit is formed. can do. For this reason, it is not necessary to separately provide complicated wiring for reading and transferring the signal charge, and the manufacturing yield can be improved.

By the way, in the solid-state imaging device according to the present embodiment, a plurality of semiconductor chips 10 formed independently of each other are vertically stacked, so that a desired semiconductor chip 10 can be interposed between adjacent semiconductor chips 10. It is also possible to further configure a layer having the above functions.
In the following second to fifth embodiments, an example will be described in which a layer having a desired function is formed between the stacked semiconductor chips 10 and 10.

<3. Second Embodiment: Example in which Color Filter is Formed>
FIG. 6 shows a schematic cross-sectional configuration of a solid-state imaging device according to the second embodiment of the present invention. FIG. 6 is a schematic cross-sectional configuration for one pixel of the solid-state imaging device of FIG. 6, parts corresponding to those in FIG. 2B are denoted by the same reference numerals, and redundant description is omitted.

  In the solid-state imaging device according to this embodiment, the yellow filter 19 is formed on the surface (back surface) opposite to the light incident side of the substrate 12b constituting the first semiconductor chip 10b. A red filter 20 is formed on the surface (back surface) opposite to the light incident side of the substrate 12g constituting the second semiconductor chip 10g. The yellow filter 19 and the red filter 20 are formed on the back side of the substrates 12b and 12g immediately below the light receiving sensor portions 4b and 4g. The yellow filter 19 is a color filter that transmits only light Lg and Lr having a yellow wavelength, that is, green (G) and red (R) wavelengths. The red filter 20 is a color filter that transmits only light Lr having a red (R) wavelength.

  Also in the solid-state imaging device of this embodiment example having such a configuration, signal charges are generated, accumulated, and transferred by the same operation as the solid-state imaging device of the first embodiment example.

  In the solid-state imaging device of the present embodiment, a yellow filter 19 is formed between the first semiconductor chip 10b and the second semiconductor chip 10g, and a red filter 20 is interposed between the second semiconductor chip 10g and the third semiconductor chip 10r. Is formed. For this reason, the blue (B) light Lb that could not be absorbed by the light receiving sensor unit 4b of the first semiconductor chip 10b is absorbed by the yellow filter 19, and only the green (G) and red (R) light Lg, Lr. Enters the light receiving sensor portion 4g of the second semiconductor chip 10g. The green (G) light Lg that could not be absorbed by the light receiving sensor unit 4g of the second semiconductor chip 10g is absorbed by the red filter 20, and only the red (R) light Lr is received by the third semiconductor chip 10r. The light enters the sensor unit 4r. Thereby, since color separation is made completely, the occurrence of color mixing can be effectively suppressed.

<4. Third Embodiment: Example in which Color Filter and Support Layer are Formed>
FIG. 7 shows a schematic cross-sectional configuration of a solid-state imaging device according to the third embodiment of the present invention. FIG. 7 is a schematic cross-sectional configuration for one pixel of the solid-state solid-state imaging device of FIG. In FIG. 7, parts corresponding to those in FIG. 2B and FIG.

  In the solid-state imaging device according to this embodiment, the support layer 21 is formed on the entire surface including the surface on which the yellow filter 19 is formed on the back surface of the substrate 12b constituting the first semiconductor chip 10b. Further, the support layer 22 is formed on the entire surface including the surface on which the red filter 20 is formed on the back surface of the substrate 12g constituting the second semiconductor chip 10g. The support layers 21 and 22 are formed to improve the substrate strength of the first semiconductor chip 10b and the second semiconductor chip 10g, do not absorb light, are conductive, and have a certain strength. Must be a layer. As the material of the support layers 21 and 22, for example, a transparent conductive material such as ITO can be used. The support layers 21 and 22 can be formed by adhering and holding on the respective substrate surfaces by a known method.

  As described above, the thickness of the substrate 12b that absorbs the blue (B) light Lb and the substrate 12g that absorbs the green (G) light Lg needs to be very thin, and there is a concern about difficulty in processing. The In this embodiment, the first semiconductor chip 10b and the second semiconductor chip are supported by supporting the substrate 12b constituting the first semiconductor chip 10b and the substrate 12g constituting the second semiconductor chip 10g with the support layers 21 and 22. The strength can be improved by 10 g.

  As described above, in this embodiment, the light receiving sensor portions 4b, 4g, and 4r corresponding to RGB are formed on the independent substrates 12b, 12g, and 12r, and the substrates 12b, 12g, and 12r are stacked. It has a structure. For this reason, when the substrate strength of the substrate constituting each semiconductor chip 10 is low, it is possible to form a support layer over the entire substrate surface of the semiconductor chip 10.

<5. Fourth Embodiment: Example in which Support Layer also Functions as Color Filter>
FIG. 8 shows a schematic cross-sectional configuration of a solid-state imaging device according to the fourth embodiment of the present invention. FIG. 8 is a schematic cross-sectional configuration for one pixel of the solid-state imaging device of FIG. 8, parts corresponding to those in FIG. 2B are denoted by the same reference numerals, and redundant description is omitted.

In the solid-state imaging device of this embodiment, a support layer 23 that also serves as a yellow filter is formed on the back surface of the substrate 12b that constitutes the first semiconductor chip 10b. Further, a support layer 24 also serving as a red filter is formed on the back surface of the substrate 12g constituting the second semiconductor chip 10g.
The support layer 23 also serving as the yellow filter can be formed, for example, by dyeing a transparent conductive material such as ITO with a yellow pigment. Similarly, the support layer 24 also serving as a red filter can be formed by dyeing a transparent conductive material such as ITO with a red pigment.

  In the solid-state imaging device of the present embodiment, the same effects as those of the third embodiment can be obtained, and the support layers 23 and 24 are also configured to serve as a color filter. Therefore, the solid-state imaging device is manufactured in comparison with the third embodiment. The number of processes at the time can be reduced.

<6. Fifth Embodiment: Example in which the thickness of the substrate is different between the light receiving unit and the charge transfer unit in the semiconductor chip>
FIG. 9 shows a schematic cross-sectional configuration of a solid-state imaging device according to the fifth embodiment of the present invention. FIG. 9 is a schematic cross-sectional configuration for one pixel of the solid-state imaging device of FIG. In FIG. 9, parts corresponding to those in FIG.

  In the solid-state imaging device according to the present embodiment, the substrate constituting each semiconductor chip 10 is formed such that the thickness of the substrate is different between the portion where the light receiving sensor unit 4 is formed and the other portions.

In the substrate 25b constituting the first semiconductor chip 10b, the thickness of the portion where the light receiving sensor portion 4b is formed is about 0.6 μm, and the thickness of the other portion is larger than 0.6 μm.
In the substrate 25g constituting the second semiconductor chip 10g, the thickness of the portion where the light receiving sensor portion 4g is formed is about 1.7 μm, and the thickness of the other portion is thicker than 1.7 μm.
In the substrate 25r constituting the third semiconductor chip 10r, the pn junction of the light receiving sensor portion 4r is formed to a depth of 3.7 μm from the surface of the substrate 25r. Further, in the substrate 25r, the thickness of the other portion is thicker than the portion where the light receiving sensor portion 4r is formed.
The thicknesses of the substrates 25b, 25g, and 25r where the light receiving sensor portions 4b, 4g, and 4r are formed are determined for the same reason as in the first embodiment.

  As described above, in the solid-state imaging device according to the present embodiment, only the thickness of the portion where the light receiving sensor portions 4b, 4g, and 4r are formed may be a thickness that can absorb light of a predetermined wavelength. For this reason, it is necessary to make the thicknesses of the substrates 25b, 25g, and 25r where the light receiving sensor portions 4b, 4g, and 4r are formed, and other portions where the vertical transfer registers 5b, 5g, and 5r are formed, for example, the same. Absent. In the present embodiment, the substrates 25b, 25g, and 25r other than the portions where the light receiving sensor portions 4b, 4g, and 4r are formed are formed thicker than the light receiving sensor portions 4b, 4g, and 4r. The substrate strength can be improved.

  Thus, even when it is necessary to thinly form the portions where the light receiving sensor portions 4b, 4g, 4r are formed, the substrates 25b, 25g, 25r other than the region where the light receiving sensor portions 4b, 4g, 4r are formed are thickened. By forming, the substrate strength can be improved.

<7. Sixth Embodiment: Example of Direct Bonding of Adjacent Semiconductor Chips>
FIG. 10 shows a schematic cross-sectional configuration of a solid-state imaging device according to the sixth embodiment of the present invention. FIG. 10 is a schematic cross-sectional configuration for one pixel of the solid-state imaging device of FIG. 10, parts corresponding to those in FIG. 8 are denoted by the same reference numerals, and redundant description is omitted.

  In the solid-state imaging device according to this embodiment, passivation films 27b, 27g, and 27r are formed on the upper surfaces of the substrates 12b, 12g, and 12r constituting the first to third semiconductor chips 10b, 10g, and 10r, respectively. The passivation films 27b, 27g, and 27r are formed to protect the entire surface of the substrate including the vertical transfer registers 5b, 5g, and 5r. For example, the passivation films 27b, 27g, and 27r are formed of a silicon nitride film, titanium oxide, silicon oxide, or the like. Yes. The upper surfaces of the passivation films 27b, 27g, and 27r are flattened, and the adjacent first to third semiconductor chips 10b, 10g, and 10r are directly bonded to each other. In this example, the lower surface of the support layer 23 formed on the first semiconductor chip 10b and the upper surface of the passivation film 27g formed on the second semiconductor chip 10g are bonded together. Further, the lower surface of the support layer 24 formed on the second semiconductor chip 10g and the upper surface of the passivation film 27r formed on the third semiconductor chip 10r are bonded together.

  As described above, in the solid-state imaging device according to the present embodiment, the passivation film formed on the upper surface of the substrate is flattened, and the first to third semiconductor chips 10b, 10g, and 10r adjacent to each other are directly bonded. The strength of the entire solid-state imaging device can be improved.

  The first to sixth embodiments described above have been described using a CCD solid-state imaging device. However, the present invention is not limited to a CCD solid-state imaging device, and is applied to a CMOS solid-state imaging device. can do. In that case, the pixel portion of the CMOS solid-state imaging device can also be configured to stack a plurality of semiconductor chips.

<8. Seventh Embodiment: Example Applied to CMOS Type Solid-State Imaging Device>
FIG. 11 shows a schematic cross-sectional configuration of a semiconductor chip constituting one pixel of a pixel portion of a CMOS type solid-state imaging device.

  As shown in FIG. 11, the semiconductor chip 30 of the present embodiment has a light receiving sensor portion 32 made of a photodiode and a plurality of MOS transistors on the surface side of a substrate 31 made of a p-type silicon substrate. The plurality of MOS transistors are a charge readout transistor Tr1, a reset transistor Tr2, and an amplifier transistor Tr3, respectively. In a semiconductor chip, a plurality of pixels are arranged in a two-dimensional matrix.

  The photodiode that constitutes the light receiving sensor unit 32 includes a hole accumulation region 34 composed of a p-type high-concentration impurity region formed in order from the surface of the substrate 31 in a required depth direction, and a charge accumulation composed of an n-type impurity region. An area 33 is included. In the present embodiment, the photodiode serving as the light receiving sensor unit 32 is mainly configured by a pn junction j formed at the interface between the charge storage region 33 and the p-type impurity region of the substrate 31. The light incident on the light receiving sensor unit 32 is photoelectrically converted by the photodiode, thereby generating a signal charge. Then, the generated signal charge is accumulated in the charge accumulation region 33 composed of an n-type impurity region.

  The charge readout transistor Tr1 includes a gate electrode 38 and source / drain regions 35. The gate electrode 38 is formed on the substrate 31 adjacent to the region where the photodiode is formed via an insulating film (not shown). The source / drain region 35 is formed of an n-type high concentration impurity region on the surface side of the substrate 31 adjacent to the gate electrode 38. This source / drain region 35 constitutes a floating diffusion region.

  The reset transistor Tr <b> 2 includes source / drain regions 35 and 36 and a gate electrode 39. The gate electrode 39 is formed on the substrate 31 in a region adjacent to the source / drain region 35 via an insulating film (not shown). The source / drain region 36 is formed of an n-type high concentration impurity region on the surface side of the substrate 31 adjacent to the gate electrode 39.

  The amplifier transistor Tr3 includes source / drain regions 36 and 37 and a gate electrode 40. The gate electrode 40 is formed on an insulating film (not shown) on the substrate 31 adjacent to the region where the source / drain region 36 is formed. The source / drain region 37 is formed of an n-type high concentration impurity region on the surface side of the substrate 31 adjacent to the gate electrode 40.

A column signal line Hs serving as an output unit is connected to the source / drain region. The source / drain region 36 is connected to the power supply wiring Vdd.
The gate electrode 40 constituting the amplifier transistor Tr3 and the source / drain region 35 serving as a floating diffusion region are connected by a wiring 41.

  In this embodiment, the solid-state imaging device of the present invention can be configured by stacking the semiconductor chips 30 shown in FIG. 11 in a plurality of stages. For example, the configuration of the light receiving sensor unit 32 of each semiconductor chip 30 is the same as in the first to sixth embodiments, and the signal charges corresponding to the RGB light in each semiconductor chip 30 are stacked by three layers. Can be generated and stored. That is, three semiconductor chips 30 with different thicknesses of the substrate 31 may be stacked in three layers as shown in FIG. 2B. At this time, the column signal line Hs connected to the source / drain region 37 constituting the amplifier transistor Tr3 of the semiconductor chip 30 is connected to the vertical transfer registers 5b, 5g, and 5r, which are formed in FIG. By replacing with, it can be seen as the solid-state imaging device of the present embodiment example.

  As described above, the present invention can be applied to any solid-state imaging device having a light receiving sensor portion made of a photodiode in a substrate.

<9. Eighth Embodiment>
[Configuration example of electronic equipment]
Hereinafter, embodiments in which the above-described solid-state imaging devices according to the first to seventh embodiments of the present invention are used in an electronic apparatus will be described. In the following description, an example in which the solid-state imaging device 1 shown in FIG. 1 is used as a camera will be described as an example.

  FIG. 12 shows a schematic cross-sectional configuration of a camera according to an embodiment of the present invention. The camera according to the present embodiment is an example of a video camera capable of capturing still images or moving images.

  The camera according to this embodiment includes a solid-state imaging device 1, an optical lens 210, a shutter device 211, a drive circuit 212, and a signal processing circuit 213.

The optical lens 210 forms image light (incident light) from the subject on the upper surface of the imaging surface of the solid-state imaging device 1. Thereby, signal charges are accumulated in the solid-state imaging device 1 for a certain period.
The shutter device 211 controls a light irradiation period and a light shielding period for the solid-state imaging device 1.
The drive circuit 212 supplies a drive signal that controls the transfer operation of the solid-state imaging device 1 and the shutter operation of the shutter device 211. Signal transfer of the solid-state imaging device 1 is performed by a drive signal (timing signal) supplied from the drive circuit 212. The signal processing circuit 213 performs various signal processing. The video signal subjected to the signal processing is stored in a storage medium such as a memory or output to a monitor.

  According to this embodiment, a camera with reduced afterimages and false colors and improved sensitivity can be obtained.

It is a schematic block diagram of the solid-state imaging device in the 1st-6th embodiment of this invention. 2A and 2B are a perspective view and a schematic cross-sectional configuration diagram for one pixel of the solid-state imaging device according to the first embodiment of the present invention. It is a section lineblock diagram of a semiconductor chip which constitutes a solid imaging device concerning a 1st embodiment. It is the figure which showed the wavelength dependence of the absorption length of the light absorbed by silicon | silicone. It is a perspective view of the pixel part of the solid-state imaging device concerning a 1st embodiment. It is a schematic sectional drawing of the solid-state imaging device concerning the 2nd Embodiment of this invention. It is a schematic sectional drawing of the solid-state imaging device concerning the 3rd Embodiment of this invention. It is a schematic sectional drawing of the solid-state imaging device concerning the 4th Embodiment of this invention. It is a schematic sectional drawing of the solid-state imaging device concerning the 5th Embodiment of this invention. It is a schematic sectional drawing of the solid-state imaging device concerning the 6th Embodiment of this invention. It is a schematic cross-section block diagram of the semiconductor chip which comprises the solid-state imaging device concerning the 7th Embodiment of this invention. It is a schematic block diagram of the electronic device which concerns on the 8th Embodiment of this invention. It is a general | schematic cross-section structure of the solid-state imaging device of a prior art example.

Explanation of symbols

1..Solid-state imaging device, 3..Pixel unit, 4,4b, 4g, 4r..Light receiving sensor unit, 5,5b, 5g, 5r..Vertical transfer register, 6..Horizontal transfer register, 7..Pixel 8... Output circuit 9... Connection pad 10... Semiconductor chip 10 b... First semiconductor chip 10 g... Second semiconductor chip 10 r. , 12b, 12g, 12r... Substrate, 13.. P-type semiconductor well region, 14... Charge storage region, 15 .. hole storage region, 16 .. transfer electrode, 17. Read-out unit, 19 ... yellow filter, 20 ... red filter, 21, 22, 23, 24 ... support layers 25b, 25g, 25r ... substrate, 27b, 27g, 27r ... passivation film, 30 ... semiconductor chip 3 ..Substrate 32..Light receiving sensor part 33..Charge storage region 34..Hole storage region 35, 36, 37..Source / drain region 38, 39, 40..Gate electrode 41. · Wiring, 100 ·· Si substrate, 102 ·· n-type semiconductor layer, 104 ·· p-type semiconductor layer, 106 ·· n-type semiconductor layer, 210 ·· Optical lens, 211 ·· Shutter device, 212 ·· Drive circuit 213... Signal processing circuit, Hs .. column signal line, Lb, Lg, Lr .. light, Tr1... Charge readout transistor, Tr2 .. reset transistor, Tr3 .. amplifier transistor, Vdd. ..PN junction

Claims (7)

A semiconductor chip that has a light receiving sensor part in a substrate that receives light to generate and store signal charges, and a plurality of semiconductor chips that generate and store signal charges according to light of different wavelengths have a predetermined interval. And having a pixel portion configured by being stacked in a plurality of stages ,
The semiconductor chip has an output unit that reads and outputs the signal charges accumulated in the light receiving sensor unit,
The thickness of the substrate constituting the semiconductor chip is the thinnest among the semiconductor chips arranged on the light incident side among the plurality of semiconductor chips constituting the pixel portion, and is opposite to the light incident side. A solid-state imaging device formed to be thickest in a semiconductor chip disposed on the side . Each of the semiconductor chips constituting the pixel unit includes, in order from the light incident side, a first semiconductor chip having a light receiving sensor unit that generates and accumulates signal charges according to light of blue wavelength, and light of green wavelength. generating a signal charge in response to the second semiconductor chip having a light receiving sensor section for storing, according to claim 1 generating a signal charge in response to light in the red wavelength, which is the third semiconductor chip having a light receiving sensor section for storing the solid-state imaging device according to. The solid-state imaging device according to claim 1, wherein the pixel unit includes a color filter layer that transmits only light of a predetermined wavelength between adjacent semiconductor chips. The solid-state imaging device according to claim 1, wherein the pixel unit includes a support layer that reinforces the semiconductor chip between adjacent semiconductor chips. 5. The solid-state imaging device according to claim 1, wherein the plurality of stages of semiconductor chips constituting the pixel unit are connected to each other by a connection pad made of a conductive member. The solid-state imaging device according to any one of claims 1 to 5 , wherein a thickness of a substrate constituting the semiconductor chip is different between a portion where the light receiving sensor portion is formed and a portion where the output portion is formed. An optical lens,
A solid-state imaging device ;
A signal processing circuit for processing an output signal of the solid-state imaging device ,
The solid-state imaging device
A semiconductor chip having a light receiving sensor part in a substrate for receiving and generating and storing signal charges by receiving light, and a plurality of semiconductor chips for generating and storing signal charges corresponding to light of different wavelengths have a predetermined interval. have a pixel portion which is formed by laminating a plurality of stages comprises,
The semiconductor chip has an output unit that reads and outputs the signal charges accumulated in the light receiving sensor unit,
The thickness of the substrate constituting the semiconductor chip is the thinnest among the semiconductor chips arranged on the light incident side among the plurality of semiconductor chips constituting the pixel portion, and is opposite to the light incident side. An electronic device formed to be the thickest in the semiconductor chip disposed on the side .

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