CN102623476B - Self-powered CMOS (Complementary Metal-Oxide-Semiconductor Transistor) image sensor - Google Patents

Self-powered CMOS (Complementary Metal-Oxide-Semiconductor Transistor) image sensor Download PDF

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CN102623476B
CN102623476B CN201210113012.6A CN201210113012A CN102623476B CN 102623476 B CN102623476 B CN 102623476B CN 201210113012 A CN201210113012 A CN 201210113012A CN 102623476 B CN102623476 B CN 102623476B
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photosensitive layer
lamination
sensitization
image sensor
light
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CN102623476A (en
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孙涛
汪辉
方娜
田犁
苗田乐
陈杰
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Chongqing Shenggang Photoelectric Technology Co.,Ltd.
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Shanghai Advanced Research Institute of CAS
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Abstract

The invention provides a self-powered CMOS (Complementary Metal-Oxide-Semiconductor Transistor) image sensor, which at least comprises a substrate layer, a photosensitive laminate laminated on the substrate layer and a pixel reading unit, wherein a line bus, an amplifier, a current source unit, an image processing unit and an energy storage unit for self power supply are located in the substrate layer; the photosensitive laminate comprises a plurality of photosensitive layers which cover the substrate layer in a lamination manner and are used for absorbing light of different wave bands, and each photosensitive layer at least comprises two switch elements and a photosensitive element connected between the two switch elements; and the pixel reading unit is located in the substrate layer or in at least one photosensitive layer of the photosensitive laminate. According to the invention, by the adoption of the photosensitive laminate of the lamination structure without optical filters, one pixel has the capacity of detecting the light of different wave bands and the image sensor has the function of self power supply, so that not only are the cost and complexity reduced and the conversion efficiency, the image quality and the integration degree of the image sensor greatly increased, but also the adaptability of the image sensor is enhanced while the light energy is utilized fully.

Description

Self energizing cmos image sensor
Technical field
The present invention relates to a kind of cmos image sensor, particularly relate to a kind of self energizing cmos image sensor, belong to technical field of semiconductors.
Background technology
As everyone knows, imageing sensor is a kind ofly optical imagery can be converted to the semiconductor device of the signal of telecommunication.Imageing sensor can be divided into charge coupled cell (CCD) and complementary metal oxide semiconductors (CMOS) (CMOS) imageing sensor substantially.
Cmos image sensor generally consists of photo-sensitive cell and cmos signal treatment circuit.Common cmos image sensor is active pixel type imageing sensor (APS) at present, the transistorized number comprising according to it is mainly divided into and comprises reset transistor (Reset Transistor, RST), transistor (Source Follower Transistor is followed in source, SF) and row selecting transistor (Row Select, RS) three pipe imageing sensors (3T type) and comprise that reset transistor (RST), source follow four of transistor (SF), row selecting transistor (RS) and transfering transistor (Transfer Transistor, TX) and manage imageing sensor (4T type) two large classes.
On the one hand, when existing cmos image sensor detects visible ray, conventionally first use the filter of three kinds of colors of red, green, blue to stop that other light pass through, then by imageing sensor (being generally photodiode or CCD), detect the light of respective color.At least there is following shortcoming in this imageing sensor with three kinds of color filters of red, green, blue that is widely used in detecting natural daylight: first, because a pixel is comprised of three or more imageing sensors, cause image area sensor larger, thereby inevitably can cause picture quality variation; Secondly, the performance of filter itself can change along with the variation of temperature and the passing of time, and then affects the quality of imaging; Finally, owing to will using filter, therefore cause the increase of cost.Although current prismatic decomposition 3CCD technology can address the above problem, the increase of the cost that it brings is also quite huge.
On the other hand, existing cmos image sensor all carries out respectively conventionally for the detection of ultraviolet light, visible ray, infrared light, does not have a kind of imageing sensor that can simultaneously detect several different-waveband light.
Finally, existing cmos image sensor, can't be for self providing power supply to reach self-energizing function when detecting light.
Summary of the invention
The shortcoming of prior art in view of the above, the object of the present invention is to provide a kind of self energizing cmos image sensor, for solving prior art, detect the image area sensor performance change large and filter itself that the imageing sensor of natural daylight uses filter to cause and cause picture quality variation, and the problem that increases imageing sensor cost, also for solving prior art, need to realize ultraviolet light with different imageing sensors, visible ray, the problem of infrared light detection, solved simultaneously and cannot realize the problem of self-energizing imageing sensor in prior art.
For achieving the above object and other relevant objects, the invention provides a kind of self energizing cmos image sensor, at least comprise:
Substrate layer, at least comprise the column bus that is positioned at wherein, amplifier, in order to provide the current source cell of constant current, the graphics processing unit of processing in order to image and for the energy-storage units of self-supply power source, wherein, described graphics processing unit at least comprises clock and control circuit, row, column, layer decoder circuit, sampling hold circuit, analog to digital converter, image processor; Described energy-storage units comprises charge storage circuit and power-switching circuit, so that the electric charge of storage is converted to suitable voltage by described power-switching circuit, for described cmos image sensor provides power supply; Described amplifier is all connected with column bus with current source cell;
Sensitization lamination, the described substrate layer of stacked covering surface, in order to absorb the light of different-waveband simultaneously, at least comprise stacked cover on described substrate layer for absorbing respectively a plurality of photosensitive layers of this different-waveband light, and respectively in this photosensitive layer, at least comprise two switch elements and be connected in a photo-sensitive cell between these two switch elements;
Pixel sensing element, be arranged in substrate layer or be arranged at least one photosensitive layer of described sensitization lamination, at least comprise connect the reset transistor of described photosensitive layer, transistor is followed in the source that connects described reset transistor and photosensitive layer, and connect described source and follow transistorized row selecting transistor.
Alternatively, described sensitization lamination at least comprise stacked cover on described substrate layer for absorb the first photosensitive layer of the first band of light and be layered on described the first photosensitive layer for absorbing the second photosensitive layer of the second band of light.
Alternatively, described sensitization lamination also comprise be layered on described the second photosensitive layer for absorbing the 3rd photosensitive layer of triband light.
Alternatively, in described the first photosensitive layer, by being adulterated, germanium forms in order to absorb the germanium material photo-sensitive cell of infrared light, in described the second photosensitive layer, by silicon is adulterated, form in order to absorb the silicon materials photo-sensitive cell of visible ray, in described the 3rd photosensitive layer, by carborundum is adulterated, form in order to absorb the carbofrax material photo-sensitive cell of ultraviolet light.
Alternatively, respectively the material of this photosensitive layer is the photon energy of energy gap and the required absorption semi-conducting material that matches, and is selected from respectively carborundum, silicon, germanium or germanium silicon, or is selected from respectively carborundum, silicon, germanium or germanium silicon through doping.
Alternatively, respectively this photosensitive layer in described sensitization lamination is semi-conducting material of the same race.
Alternatively, between described substrate layer and sensitization lamination, have in insulating barrier and/or described sensitization lamination and there is insulating barrier between each photosensitive layer.
Alternatively, the photosensitive layer in described sensitization lamination is the compound photosensitive layer being comprised of a plurality of sensitization sublayer.
Alternatively, respectively between this sensitization sublayer, there is insulating barrier.
Alternatively, respectively this photo-sensitive cell of described sensitization lamination is at least one in PN junction photodiode, pinprick formula photodiode or photoelectricity door.
Alternatively, described pixel sensing element is arranged in a photosensitive layer of described sensitization lamination, all photo-sensitive cells of described sensitization lamination share described pixel sensing element, and respectively between this photo-sensitive cell and described pixel sensing element, by the switch element that respectively this photo-sensitive cell is corresponding, connect, wherein, described sensitization lamination and pixel sensing element form a picture element module.
Alternatively, a plurality of described pixel sensing elements lay respectively in a plurality of photosensitive layers of described sensitization lamination, a plurality of pixel sensing elements described in all photo-sensitive cell correspondences of described sensitization lamination, and each photo-sensitive cell of described sensitization lamination is only connected with a described pixel sensing element by its each self-corresponding switch element, wherein, described sensitization lamination and a plurality of described pixel sensing element form a picture element module.
Alternatively, described pixel sensing element is arranged in substrate layer, and all photo-sensitive cells of described sensitization lamination share described pixel sensing element, and wherein, described sensitization lamination is a picture element module.
As mentioned above, for existing cmos image sensor, self energizing cmos image sensor of the present invention, has following beneficial effect:
1) the present invention is owing to having adopted the design of free of light filter, the problems such as picture quality variation of also having avoided filter to cause when reducing costs;
2) the present invention, owing to adopting the sensitization lamination of stacked structure, makes required circuit structure can be made in (substrate layer) on independent one deck, thereby greatly improves fill factor, curve factor, further improves the quality of image;
3) the present invention is owing to adopting the sensitization lamination of stacked structure, make a pixel there is the ability that detects different-waveband light, single exposure can obtain the information such as ultraviolet light, visible ray and infrared light simultaneously, on the one hand, can obtain much information by chip piece, not only reduce cost and complexity, and greatly improved efficiency and the picture quality of conversion; On the other hand, when reading information needed, the residual charge that can selectively different photosensitive layers be produced saves, and provide power supply by power-switching circuit for whole imageing sensor, to realize self-energizing function, make full use of the energy of light, and strengthened the adaptive capacity of imageing sensor;
4) self energizing cmos image sensor provided by the invention, can be positioned at red, blue, the preparation of green glow sensor devices on the different laminations of Semiconductor substrate the same area in order to realize the accurate imaging of visible ray, has further improved the integrated level of imageing sensor.
Accompanying drawing explanation
Fig. 1 is shown as the equivalent circuit structure schematic diagram of self energizing cmos image sensor of the present invention in embodiment mono-.
Three-dimensional structure schematic diagram when the sensitization lamination that Fig. 2 a to Fig. 2 e is shown as self energizing cmos image sensor of the present invention is different structure.
Fig. 3 is shown as in self energizing cmos image sensor of the present invention different-waveband light intensity and enters the schematic diagram that is related to of depth of material.
Fig. 4 a to Fig. 4 b is shown as different equivalent circuit structure schematic diagrames corresponding to picture element module that form in self energizing cmos image sensor of the present invention.
Fig. 5 is shown as the equivalent circuit structure figure schematic diagram of self energizing cmos image sensor of the present invention in embodiment bis-.
Element numbers explanation
1 substrate layer
11 column bus
12 amplifiers
13 current source cells
14 graphics processing units
15 energy-storage units
2 sensitization laminations
21 infrared light photosensitive layers
22 visible ray photosensitive layers
The sensitization sublayer of 22a, 22b, 22c visible ray photosensitive layer
23 ultraviolet light photosensitive layers
21 ' ruddiness photosensitive layer
22 ' green glow photosensitive layer
23 ' blue light photosensitive layer
212,222,232,212 ', 222 ', 232 ' PN junction photodiode, photo-sensitive cell
2111,2112,2211,2212,2311,2312 switch elements
2111 ', 2112 ', 2211 ', 2212 ', 2311 ', 2312 ' switch element
3,3 ' pixel sensing element
31,31 ' reset transistor
32, transistor is followed in 32 ' source
33,33 ' row selecting transistor
341,342,343 transfering transistors
351,352,353 floating diffusion regions
41,421,422,422a～c, 41 ", 421 ", 422 " insulating barriers
5,5 ' picture element module
6,6 ' picture element module array
Embodiment
Below, by specific instantiation explanation embodiments of the present invention, those skilled in the art can understand other advantages of the present invention and effect easily by the disclosed content of this specification.The present invention can also be implemented or be applied by other different embodiment, and the every details in this specification also can be based on different viewpoints and application, carries out various modifications or change not deviating under spirit of the present invention.
Refer to Fig. 1 to Fig. 5.It should be noted that, the diagram providing in following specific embodiment only illustrates basic conception of the present invention in a schematic way, satisfy and only show with assembly relevant in the present invention in graphic but not component count, shape and size drafting while implementing according to reality, during its actual enforcement, kenel, quantity and the ratio of each assembly can be a kind of random change, and its assembly layout kenel also may be more complicated.
The cmos image sensor of existing detection visible ray is the imageing sensor with three kinds of color filters of red, green, blue, use due to filter, cause the increase of cost, cause that image area sensor causes more greatly picture quality variation, and the performance change of filter itself also affects the quality of imaging; Existing cmos image sensor all carries out respectively conventionally for the detection of ultraviolet light, visible ray, infrared light, does not have a kind of imageing sensor that can simultaneously detect several different-waveband light; Existing cmos image sensor, can't be for self providing power supply to reach self-energizing function when detecting light.
Given this, the invention provides a kind of self energizing cmos image sensor, at least comprise substrate layer, stacked sensitization lamination and the pixel sensing element covering on substrate layer, wherein, column bus, amplifier, current source cell, graphics processing unit and be positioned at substrate layer for the energy-storage units of self-supply power source; Sensitization lamination comprise stacked cover on described substrate layer for absorbing a plurality of photosensitive layers of different-waveband light, and respectively in this photosensitive layer, at least comprise two switch elements and be connected in a photo-sensitive cell between these two; Pixel sensing element is arranged in substrate layer or is arranged at least one photosensitive layer of sensitization lamination.The present invention adopts the sensitization lamination of the stacked structure of free of light filter, can realize a pixel and there is ability and the self-energizing function of imageing sensor that detects different-waveband light, cost and complexity have not only been reduced, greatly improve conversion efficiency, picture quality and the integrated level of imageing sensor, and when making full use of the energy of light, strengthened the adaptive capacity of imageing sensor.
Embodiment mono-
As shown in Figures 1 to 4, the invention provides a kind of self energizing cmos image sensor, at least comprise:
Be arranged in column bus 11, amplifier 12, current source cell 13, graphics processing unit 14 and the energy-storage units 15 of substrate layer 1; In the stacked sensitization lamination 2 covering on described substrate layer 1 for absorbing a plurality of photosensitive layers of different-waveband light, in the present embodiment one, for for absorbing three photosensitive layers of three band of light, wherein, the first photosensitive layer is that infrared light photosensitive layer 21, the second photosensitive layers are that visible ray photosensitive layer 22, the 3rd photosensitive layer are ultraviolet light photosensitive layer 23; And at least comprise that reset transistor 31, source follow the pixel sensing element 3 of transistor 32 and row selecting transistor 33, in the present embodiment one, described self energizing cmos image sensor is 4T type, and described pixel sensing element 3 also comprises and lays respectively at respectively transfering transistor 341～343 and the floating diffusion region 351～353 of this photosensitive layer.
Described substrate layer 1 material is semi-conducting material or organic film material, wherein, described semi-conducting material is silicon, germanium or germanium silicon, described organic film material is ZnO-TFT, and the semiconductor structure of the semiconductor structure that the structure of described substrate layer 1 is homogenous material or tape insulation buried regions, in the present embodiment one, described substrate layer 1 is body silicon, but be not limited to this, in another embodiment, described substrate layer 1 is germanium on insulator (GOI).
As shown in Figure 1, described substrate layer 1 at least comprises and being positioned at wherein:
Described column bus 11 is connected with described amplifier 12, current source cell 13 and pixel sensing element 3.
Described amplifier 12 is in order to amplify the signal of telecommunication that comprises Pixel Information of reading through described pixel sensing element 3, wherein, an input is connected with described column bus, another input end grounding, and export the signal of telecommunication that comprises Pixel Information after amplifying to described graphics processing unit 14.
Described current source cell 13 comprises providing the circuit (not shown) of constant current, makes the source in described pixel sensing element 3 follow the grid source electric current (I of transistor 32 ds) keep constant, for guaranteeing that source voltage and grid voltage are poor constant, thereby reach the object of source voltage follow grid voltage, wherein, one end of described current source cell 13 is connected with amplifier 12 with described column bus 11, other end ground connection.
Described graphics processing unit 14 is connected with the output of described amplifier 12, at least comprise clock and control circuit, row, column, layer decoder circuit, sampling hold circuit, analog to digital converter, image processor (not shown), in order to carry out image processing by the signal of telecommunication that comprises Pixel Information amplifying through amplifier 12.
Described energy-storage units 15 comprises charge storage circuit and power-switching circuit (not shown), for the electric charge of storage is converted to suitable voltage and is preserved by described power-switching circuit, when needs self energizing, the voltage of preservation is connected to the required power supply V of pixel sensing element 3 dd, for described pixel sensing element 3 provides drain voltage V dd, for described cmos image sensor is realized self-supply power source function.
As shown in Figure 2 a, described sensitization lamination 2 is stacked to be covered on described substrate layer 1, at least comprise stacked cover on described substrate layer 1 for absorbing a plurality of photosensitive layers of different-waveband light, in the present embodiment one, stacked covering on described substrate layer is infrared light photosensitive layer 21 for absorbing the first photosensitive layer of the first band of light (infrared light), be layered on described the first photosensitive layer (infrared light photosensitive layer 21) is visible ray photosensitive layer 22 for absorbing the second photosensitive layer of the second band of light (visible ray), and to be layered on described the second photosensitive layer (visible ray photosensitive layer 22) be ultraviolet light photosensitive layer 23 for absorbing the 3rd photosensitive layer of triband light (ultraviolet light), respectively the material of this photosensitive layer is the photon energy of energy gap and the required absorption semi-conducting material that matches, be selected from respectively carborundum, silicon, germanium, or germanium silicon, or be selected from respectively through doping carborundum, silicon, germanium, or germanium silicon, wherein, in the present embodiment one, described infrared light photosensitive layer 21 is germanium (Ge) material, described visible ray photosensitive layer 22 is silicon (Si) material, described ultraviolet light photosensitive layer 23 is carborundum (SiC) material, but be not limited to this, in another embodiment, respectively the material of this photosensitive layer can be semi-conducting material of the same race.
Respectively in this photosensitive layer, at least comprise two switch elements and be connected in a photo-sensitive cell between these two, respectively this photo-sensitive cell is PN junction photodiode, pinprick formula photodiode (Pinned Diode), or at least one in photoelectricity door, wherein, described photo-sensitive cell carries out opto-electronic conversion when exposing for imageing sensor of the present invention, the light signal receiving is converted to the signal of telecommunication that comprises Pixel Information, in the present embodiment one, respectively the photo-sensitive cell in this photosensitive layer is PN junction photodiode, but be not limited to this, in another embodiment, also there is all same cases not of photo-sensitive cell type in this photosensitive layer respectively, be respectively PN junction photodiode, pinprick formula photodiode, and a kind of (not shown) of photoelectricity door, described switch element includes the PMOS transistor of the nmos pass transistor of a nmos pass transistor, a plurality of parallel connection or series connection, PMOS transistor or a plurality of parallel connection or series connection, and in the present embodiment one, described switch element is a nmos pass transistor.
It should be noted that, photosensitive layer number described in the present embodiment one in sensitization lamination 2 is three, and (the first photosensitive layer is infrared light photosensitive layer 21, the second photosensitive layer is visible ray photosensitive layer 22, the 3rd photosensitive layer is ultraviolet light photosensitive layer 23), but and be not only confined to this, in another embodiment, photosensitive layer number in described sensitization lamination 2 also can be for only for absorbing two photosensitive layers of two kinds of different-waveband light, it comprise stacked cover on described substrate layer for absorb the first photosensitive layer of the first band of light and be layered on described the first photosensitive layer for absorbing the second photosensitive layer of the second band of light, certainly, in other embodiments, the photosensitive layer number in described sensitization lamination 2 can be also four photosensitive layers or more photosensitive layer, and this is no longer going to repeat them.
What need to further illustrate is, photosensitive layer in described sensitization lamination 2 can be the compound photosensitive layer being comprised of a plurality of sensitization sublayer, in the present embodiment one, described the first photosensitive layer (infrared light photosensitive layer 21), the second photosensitive layer (visible ray photosensitive layer 22) or the 3rd photosensitive layer (ultraviolet light photosensitive layer 23) can be distinguished or be the compound photosensitive layer being comprised of a plurality of sensitization sublayer simultaneously, for example, shown in Fig. 2 b, be the situation of only having described visible ray photosensitive layer 22 to be the compound photosensitive layer that formed by a plurality of sensitization sublayer (22a～22c).
It is pointed out that for fear of crosstalking between this photosensitive layer respectively, affect picture quality, therefore between described substrate layer 1 and sensitization lamination 2, adopt in insulating barrier and/or described sensitization lamination 2 and adopt insulating barrier to isolate between each photosensitive layer; Need to further be pointed out that, described insulating barrier 4 is single layer structure or laminated construction, and described single layer structure wherein or the material of the every one deck in described laminated construction are any one in silica, silicon nitride and silicon oxynitride.As shown in Figure 2 c, in the present embodiment one, between described substrate layer 1 and sensitization lamination 2, adopting in monolayer insulating layer 41 and described sensitization lamination 2 adopts insulating barrier (to comprise at described infrared light photosensitive layer 21 and the monolayer insulating layer 421 between visible ray photosensitive layer 22 between each photosensitive layer, and described visible ray photosensitive layer 22 and the monolayer insulating layer 422 between ultraviolet light photosensitive layer 23, now respectively this photosensitive layer is and does not comprise sensitization sublayer situation, is single layer structure) isolate; In another embodiment, when in described sensitization lamination 2, photosensitive layer is the compound photosensitive layer being comprised of a plurality of sensitization sublayer, respectively between this sensitization sublayer, there is insulating barrier, for example, shown in Fig. 2 d, only have the situation that described visible ray photosensitive layer 22 is the compound photosensitive layer that is comprised of a plurality of sensitization sublayer (22a～22c), it respectively has monolayer insulating layer 422a～422c between this sensitization sublayer (22a～22c); Further, in other embodiments, as shown in Figure 2 e, described infrared light photosensitive layer 21, visible ray photosensitive layer 22 and ultraviolet light photosensitive layer 23 are single layer structure, but described insulating barrier 41 ", 421 " and 422 " be the insulating barrier of the laminated construction of silicon nitride and silicon oxynitride.
Particularly, in the present embodiment one, as shown in Figure 2 c, the first described photosensitive layer (infrared light photosensitive layer 21), the second photosensitive layer (visible ray photosensitive layer 22) and the 3rd photosensitive layer (ultraviolet light photosensitive layer 23) are single layer structure, and between each photosensitive layer, adopt insulating barrier (to comprise at described infrared light photosensitive layer 21 and the insulating barrier 421 between visible ray photosensitive layer 22, and described visible ray photosensitive layer 22 and the insulating barrier 422 between ultraviolet light photosensitive layer 23) isolate, simultaneously, between described substrate layer 1 and sensitization lamination 2, adopt insulating barrier 41 to isolate, and described insulating barrier 41, 421 and 422 are the silicon nitride dielectric layer of single layer structure, as shown in Figure 2 c, in the present embodiment one, respectively the photo-sensitive cell in this photosensitive layer is PN junction photodiode, as shown in Figure 1, in the present embodiment one, described switch element is a nmos pass transistor, and when its grid adds high voltage, described switch element closure is conducting state, and when its grounded-grid, described switch element is opened and is off-state.
Further, in the present embodiment one, as shown in Figure 1, described infrared light photosensitive layer 21 comprises switch element 2111 and 2112 and be connected in the photo-sensitive cell (PN junction photodiode) 212 between the two, wherein, in described infrared light photosensitive layer 21, by being adulterated, germanium forms germanium PN junction photodiode photo-sensitive cell 212, comprise HeNXing district, p type island region, described p type island region ground connection, one end of described switch element 2111 is connected with described pixel sensing element 3, one end of described switch element 2112 is connected with described energy-storage units 15, and in the present embodiment one, respectively this switch element 2111 and 2112 the other end are connected to floating diffusion region (the Floating Diffusion that is arranged in infrared light photosensitive layer 21, FD) 351 (in embodiment mono-, imageing sensor of the present invention is 4T type, photo-sensitive cell (PN junction photodiode) 212NXing district is by transfering transistor (Transfer Transistor, TX) 341 be connected to floating diffusion region 351), but be not limited to this, in another embodiment, when imageing sensor of the present invention is 3T type, respectively this switch element 2111 and 2112 the other end are connected to PN junction photodiode 212NXing district, in the present embodiment one, as shown in Figure 1, described visible ray photosensitive layer 22 comprises switch element 2211 and 2212 and be connected in the photo-sensitive cell (PN junction photodiode) 222 between the two, wherein, in described visible ray photosensitive layer 22, by being adulterated, silicon forms silicon PN junction photodiode photo-sensitive cell 222, comprise HeNXing district, p type island region, described p type island region ground connection, one end of described switch element 2211 is connected with described pixel sensing element 3, one end of described switch element 2212 is connected with described energy-storage units 15, and in the present embodiment one, respectively this switch element 2211 and 2212 the other end are connected to floating diffusion region (the Floating Diffusion that is arranged in visible ray photosensitive layer 22, FD) 352 (in embodiment mono-, imageing sensor of the present invention is 4T type, photo-sensitive cell (PN junction photodiode) 222NXing district is by transfering transistor (Transfer Transistor, TX) 342 be connected to floating diffusion region 352), but be not limited to this, in another embodiment, when imageing sensor of the present invention is 3T type, respectively this switch element 2211 and 2212 the other end are connected to PN junction photodiode 222NXing district, in the present embodiment one, as shown in Figure 1, described ultraviolet light photosensitive layer 23 comprises switch element 2311 and 2312 and be connected in the photo-sensitive cell (PN junction photodiode) 232 between the two, wherein, in described ultraviolet light photosensitive layer 23, by being adulterated, carborundum (SiC) forms carborundum PN junction photodiode photo-sensitive cell (PN junction photodiode) 232, comprise HeNXing district, p type island region, described p type island region ground connection, one end of described switch element 2311 is connected with described pixel sensing element 3, one end of described switch element 2312 is connected with described energy-storage units 15, and in the present embodiment one, respectively this switch element 2311 and 2312 the other end are connected to floating diffusion region (the Floating Diffusion that is arranged in ultraviolet light photosensitive layer 23, FD) 353 (in embodiment mono-, imageing sensor of the present invention is 4T type, photo-sensitive cell (PN junction photodiode) 232NXing district is by transfering transistor (Transfer Transistor, TX) 343 be connected to floating diffusion region 353), but be not limited to this, in another embodiment, when imageing sensor of the present invention is 3T type, respectively this switch element 2311 and 2312 the other end are connected to PN junction photodiode 232NXing district.
It needs to be noted, the light of different wave length has different response characteristics in same semi-conducting material, only has as semiconductor energy bandwidth E gbe less than the photon energy E of incident light ph(E ph=h υ=hc/ λ) time, semiconductor just can absorb photon and produce electron-hole pair, and different semi-conducting materials represent the available absorption coefficient a of the power of different wave length light absorption, P (x)=P 0* exp (ax), wherein, P 0for incident intensity, P (x) is light path x place luminous intensity in semiconductor, when x=1, and P (d)=P 0* e, definition d is photon penetration depth.Absorption coefficient a=a (λ) is the function of wavelength, it depends on wavelength strongly, absorption coefficient reduces and increases rapidly with wavelength, that is: semi-conducting material will absorb the light of different wave length, need different incident light paths, wavelength is shorter, and semi-conducting material is larger to the absorption coefficient of light, absorb incident light completely, to realize effective light path that opto-electronic conversion needs incident light to transmit in semiconductor shorter, otherwise longer.In other words, when the incident light of different wave length is absorbed in same semi-conducting material, respectively the incident light of this different wave length enters the degree of depth difference of semi-conducting material.
For the ease of absorb the light of different-waveband simultaneously, make imageing sensor of the present invention there is the ability that detects different-waveband light, the present invention adopts laminated construction in order to light absorbing described sensitization lamination 2, because respectively this photosensitive layer residing position in sensitization lamination 2 is different, therefore when respectively this photosensitive layer is semi-conducting material of the same race, also can absorb the light of different-waveband.
As shown in Figure 3, in the present embodiment one, ultraviolet light, visible ray and infrared light are three light that wave band is different, and its medium wavelength the shortest relative ultraviolet light is at the d nearer apart from incidence surface 1position is almost all absorbed, and visible ray is at the d relatively placed in the middle apart from incidence surface 2position (d 2with respect to d 1and d 3, be positioned at centre position) be almost all absorbed, and three wave band medium wavelength the longest relative infrared lights are mainly at the d far away apart from incidence surface 3position is almost all absorbed.In view of above-mentioned theory, in the present embodiment one, described ultraviolet light photosensitive layer 23 is layered on visible ray photosensitive layer 22, be positioned at sensitization lamination 2 part at the middle and upper levels, in order to ultraviolet light is almost all absorbed in the nearer position apart from the plane of incidence (surface of sensitization lamination 2), the bottom of ultraviolet light photosensitive layer 23 is apart from the distance r on the plane of incidence (surface of sensitization lamination 2) 3(or ultraviolet light photosensitive layer be compound photosensitive layer, the thickness summation of its each sublayer) is 0 and d 2between; Described visible ray photosensitive layer 22 is layered on described infrared light photosensitive layer 21, be arranged in the layer segment of sensitization lamination 2, in order to visible ray is almost all absorbed in the position relatively placed in the middle apart from the plane of incidence (surface of sensitization lamination 2), the bottom of visible ray photosensitive layer 22 is apart from the distance r on the plane of incidence (surface of sensitization lamination 2) 2(or visible ray photosensitive layer be compound photosensitive layer, the thickness summation of its each sublayer) is at r 3and d 3between; Described infrared light photosensitive layer 21 is stacked to be covered on substrate layer 1, be arranged in sensitization lamination 2 underclad portion, in order to infrared light is almost all absorbed in the position far away apart from the plane of incidence (surface of sensitization lamination 2), the bottom of infrared light photosensitive layer 21 is apart from the distance r on the plane of incidence (surface of sensitization lamination 2) 1(or infrared light photosensitive layer be compound photosensitive layer, the thickness summation of its each sublayer) is greater than r 2.
In like manner, in another embodiment, for visible ray, because blue light, green glow and red light wavelength are for increasing progressively situation, therefore blue light absorption is in the region on the most close plane of incidence (surface of sensitization lamination 2), the absorption of ruddiness concentrates on apart from the plane of incidence (surface of sensitization lamination 2) interior zone far away, and the absorption region of green glow is between between the two.
What need to further illustrate is, when the photon energy of common semi-conductive energy gap and a certain band of light matches, this band of light can well be absorbed, therefore, in described sensitization lamination 2, respectively the material of this photosensitive layer is the photon energy of energy gap and the required absorption semi-conducting material that matches, wherein, and in the present embodiment one, in order better to absorb ultraviolet light, ultraviolet light photosensitive layer 23 adopts the larger material silicon carbide of energy gap; In order better to absorb visible ray, visible ray photosensitive layer 22 adopts the material silicon of medium energy gap; In order better to absorb infrared light, infrared light photosensitive layer 21 adopts the material germanium of energy gap minimum.
Described pixel sensing element 3 (not shown) is arranged in substrate layer 1 or is arranged at least one photosensitive layer of described sensitization lamination 2, in order to the signal of telecommunication that comprises Pixel Information that described sensitization lamination 2 is obtained (respectively this photo-sensitive cell carry out opto-electronic conversion when the exposure light signal receiving is converted to the signal of telecommunication that comprises Pixel Information), affected through column bus 11 and amplifier 12 by current source cell 13 and read out to graphics processing unit 14, at least comprise reset transistor 31 (the Reset Transistor that connects described photosensitive layer, RST), transistor 32 (Source Follower Transistor is followed in the source that connects described reset transistor 31 and photosensitive layer, SF), and connect row selecting transistor 33 (the Row Select that transistor 32 is followed in described source, RS), wherein, described reset transistor 31, transistor 32 is followed in source, and row selecting transistor 33 includes a nmos pass transistor, the nmos pass transistor of a plurality of parallel connections or series connection, a PMOS transistor, or a kind of in the PMOS transistor of a plurality of parallel connections or series connection.
It is to be noted, described self energizing cmos image sensor is 3T type imageing sensor or 4T type imageing sensor, wherein, the pixel sensing element 3 (not shown) of described 4T type imageing sensor also comprises and is arranged in respectively the corresponding transfering transistor of photo-sensitive cell (the Transfer Transistor separately of this photosensitive layer, TX) 341～343 and floating diffusion region (Floating Diffusion, FD) 351～353, wherein, described transfering transistor comprises a nmos pass transistor, the nmos pass transistor of a plurality of parallel connections or series connection, a PMOS transistor, or a kind of in the PMOS transistor of a plurality of parallel connections or series connection.
In the present embodiment one, described self energizing cmos image sensor is 4T type imageing sensor, and described reset transistor 31, source followed transistor 32, row selecting transistor 33 and transfering transistor 34 and be a nmos pass transistor.But do not limit to therewith, in another embodiment, the transistor in described pixel sensing element 3 can be above-mentioned series/parallel situation or PMOS situation.
It is pointed out that described pixel sensing element 3 is arranged in substrate layer 1 or is arranged at least one photosensitive layer of described sensitization lamination 2, exists following several situations as shown in Fig. 1,4a and 4b:
As shown in Figure 1, described pixel sensing element 3 is arranged in a photosensitive layer of described sensitization lamination 2, all photo-sensitive cells of described sensitization lamination 2 share described pixel sensing element 3, and respectively between this photo-sensitive cell and described pixel sensing element 3, by the switch element that respectively this photo-sensitive cell is corresponding, connect, wherein, described sensitization lamination 2 forms a picture element module 5 with pixel sensing element 3;
As shown in Fig. 4 a, described pixel sensing element 3 is arranged in substrate layer 1, and all photo-sensitive cells of described sensitization lamination 2 share described pixel sensing element 3, and wherein, described sensitization lamination 2 is a picture element module 5;
As shown in Figure 4 b, a plurality of described pixel sensing elements 3 lay respectively in a plurality of photosensitive layers of described sensitization lamination 2, the signal of telecommunication that comprises Pixel Information of all photo-sensitive cells of described sensitization lamination 2 is read by described a plurality of pixel sensing elements 3, and each photo-sensitive cell of described sensitization lamination 2 is only connected with a described pixel sensing element 3 by its each self-corresponding switch element, wherein, described sensitization lamination 2 forms a picture element module 5 with a plurality of described pixel sensing elements 3.In other words, in a plurality of described pixel sensing element 3 in a plurality of photosensitive layers of the sensitization lamination 2 described in laying respectively at, in one embodiment, as shown in Figure 4 b, a described pixel sensing element 3 each corresponding photo-sensitive cells, described in each, photo-sensitive cell is connected by its each self-corresponding switch element described pixel sensing element 3 corresponding to it; In another embodiment, have the situation of pixel cell 3 corresponding a plurality of photo-sensitive cells, respectively this photo-sensitive cell that shares a described pixel sensing element 3 is connected by its each self-corresponding switch element shared pixel sensing element 3 corresponding with it.
Need to further be pointed out that, a plurality of described picture element modules 5 form picture element module array 6 (not shown), the signal of telecommunication that comprises Pixel Information of described picture element module array 6 transfers to graphics processing unit 14 via described pixel sensing element 3, column bus 11 and amplifier 12, so that the described signal of telecommunication that comprises Pixel Information is carried out to image processing.
Particularly, in the present embodiment one, as shown in Figure 1, described pixel sensing element 3 is arranged in a photosensitive layer of described sensitization lamination 2, wherein said photosensitive layer is visible ray photosensitive layer 22 (not illustrating the concrete structure of pixel sensing element 3 in semiconductor structure Fig. 2 c), all photo-sensitive cells of described sensitization lamination 2 (PN junction photodiode 212～232) share described pixel sensing element 3, described self energizing cmos image sensor is 4T type imageing sensor, this photo-sensitive cell (PN junction photodiode 212 respectively, 222 and 232) between each self-corresponding floating diffusion region 351～353 and described pixel sensing element 3 by the switch element 2111 that respectively this photo-sensitive cell is corresponding, 2211 and 2311 are connected, the floating diffusion region 351 of described PN junction photodiode 212 correspondences is connected with described pixel sensing element 3 by switch element 2111, the floating diffusion region 352 of described PN junction photodiode 222 correspondences is connected with described pixel sensing element 3 by switch element 2211, the floating diffusion region 353 of described PN junction photodiode 232 correspondences is connected with described pixel sensing element 3 by switch element 2311.Described sensitization lamination 2 forms a picture element module 5 with pixel sensing element 3, further, a plurality of described picture element modules 5 form picture element module array 6 (not shown), the signal of telecommunication that comprises Pixel Information of described picture element module array 6 transfers to graphics processing unit 14 via described pixel sensing element 3, described column bus 11 and amplifier 12, so that the described signal of telecommunication that comprises Pixel Information is carried out to image processing.
What need specified otherwise is, in the present embodiment one, described self energizing cmos image sensor is 4T type imageing sensor, and respectively the photo-sensitive cell of this photosensitive layer (PN junction photodiode 212,222 and 232) shares described pixel sensing element 3, as shown in Figure 1, respectively this transistorized connected mode in described pixel sensing element 3 is as follows:
Described reset transistor 31 resets to described photo-sensitive cell (PN junction photodiode 212,222 and 232) before exposure for imageing sensor of the present invention, wherein, between each self-corresponding floating diffusion region 351～353 of each photo-sensitive cell in described respectively this photosensitive layer (PN junction photodiode 212,222 and 232) and reset transistor 31, by this switch element 2111,2211 and 2311 respectively, be connected respectively, and reset function is controlled by reset signal Reset signal (the RST end points in Fig. 1).In Fig. 1, described reset transistor 31 is a nmos pass transistor, because described self energizing cmos image sensor is 4T type imageing sensor, the source electrode of described reset transistor 31 and respectively this switch element 2111, one end of 2211 and 2311 is connected, and this switch element 2111 respectively, 2211 and 2311 the other end with lay respectively at respectively this photosensitive layer in corresponding (the PN junction photodiode 212 of photo-sensitive cell separately, 222 and 232) floating empty diffusion region (FD) 351, 352 and 353 are connected, i.e. this switch element 2111 respectively, 2211 and 2311 respectively by the source electrode of described reset transistor 31 be arranged in respectively corresponding (the PN junction photodiode 212 of photo-sensitive cell separately of this photosensitive layer, 222 and 232) floating empty diffusion region (FD) 351, 352 and 353 are connected, the drain electrode of described reset transistor 31 meets power supply V dd, described power supply V ddit is a positive supply.
The constant current that transistor 32 provides by means of described current source cell 13 is followed in described source, makes its grid source electric current (I ds) keep constant, for guaranteeing that source voltage and grid voltage are poor constant, thereby reach the object of source voltage follow grid voltage, the signal of telecommunication that comprises Pixel Information producing through opto-electronic conversion for reading described photo-sensitive cell (PN junction photodiode 212,222 and 232).In Fig. 1, it is a nmos pass transistor that transistor 32 is followed in described source, because described self energizing cmos image sensor is 4T type imageing sensor, the grid of transistor 32 and each photo-sensitive cell (the PN junction photodiode 212 in described respectively this photosensitive layer are followed in described source, 222 and 232) each self-corresponding floating diffusion region 351, 352 and 353 pass through respectively respectively this switch element 2111, 2211 and 2311 are connected, now the grid of transistor 32 is followed in described source, the source electrode of reset transistor 31 all with this switch element 2111 respectively, one end of 2211 and 2311 is connected.The drain electrode that transistor 32 is followed in described source meets described power supply V dd, the source electrode that transistor 32 is followed in described source is the output that output packet contains the signal of telecommunication of Pixel Information.
Described row selecting transistor 33 is for following described source the signal of telecommunication that the comprises Pixel Information output of the source electrode output of transistor 32.In Fig. 1, described row selecting transistor M3 selects a NMOS pipe, the grid of described row selecting transistor 33 meets row selection signal RS, and the drain electrode of described row selecting transistor 33 connects the source electrode that transistor 32 is followed in described source, and the source electrode of described row selecting transistor 33 is output.
Described transfering transistor 341,342 and 343 for the signals of telecommunication that comprise Pixel Information that described PN junction photodiode 212,222 and 232 is produced by floating diffusion region 351,352 and 353 and switch element 2111,2211 and 2311 be input to the source electrode connection that grid and the reset transistor 31 of transistor 32 are followed in described source.In embodiment mono-, as shown in Figure 1, described transfering transistor 341,342 and 343 is selected a nmos pass transistor, described transfering transistor 341,342 and 343 grid switch through shifting signal TX, described transfering transistor 341,342 and 343 source electrode (not shown) meet described PN junction photodiode 212,222 Ji232NXing districts, and described transfering transistor 341,342 and 343 drain electrode connect by floating diffusion region 351,352 and 353 the source electrode connection that grid and the reset transistor 31 of transistor 32 are followed in source.
Before setting forth operation principle, it should be noted that, because this switch element is respectively nmos pass transistor, when the grid of switch element is high level, switch element is in conducting state (being that switch is closed), when the grounded-grid of switch element, switch element is in off-state (being switch opens).By switch element 2111,2211 and 2311, select the reading of the signal of telecommunication that comprises Pixel Information of different photosensitive layers, by switch element 2112,2212 and 2312, select the electric charge of different photosensitive layers process opto-electronic conversion to export to described energy-storage units 15, by described power-switching circuit, be converted to suitable voltage and preserve, when needs self energizing, the voltage of preservation is connected to the required power supply V of pixel sensing element 3 dd, for described pixel sensing element 3 provides drain voltage V dd, for described cmos image sensor is realized self-supply power source function.
The signal of telecommunication that comprises Pixel Information, storage visible ray photosensitive layer 22 and the infrared light photosensitive layer 21 that only reads ultraviolet light photosensitive layer 23 of take is example by the electric charge of its photo-sensitive cell opto-electronic conversion separately, describes the operation principle of described self energizing cmos image sensor:
Selection natural daylight is light source, before exposure, make it in off-state (being switch opens) grounded-grid of described switch element 2312, the floating empty diffusion region (FD) 353 that is arranged in the corresponding photo-sensitive cell of described ultraviolet photosensitive layer 23 (PN junction photodiode 232) disconnects with described energy-storage units 15, do not store the electric charge of the opto-electronic conversion of described ultraviolet light photosensitive layer 23, simultaneously, for providing high level, the grid of described switch element 2311 make it in conducting state (being that switch is closed), the floating empty diffusion region (FD) 353 that is arranged in the corresponding photo-sensitive cell of described ultraviolet photosensitive layer 23 (PN junction photodiode 232) is connected to the source electrode of described reset transistor 31, when the reset signal Reset of described reset transistor 31 is high level, described reset transistor 31 conductings, by the transfering transistor corresponding with it 343, (its grid switches through shifting signal TX to described PN junction photodiode 232, its source electrode meets described PN junction photodiode 232NXing district, not shown) and floating diffusion region 353 be connected to the drain power V of reset transistor 31 dd, at described power supply V ddeffect under, make described PN junction photodiode 232 partially anti-and can remove the electric charge of whole accumulations of described PN junction photodiode 232, realize and resetting.
The drain electrode that transistor 32 is followed in described source meets described power supply V dd, when described self energizing cmos image sensor is realized after reset, selecting natural daylight is that light source exposes, the photo-sensitive cell (PN junction photodiode 232) that is positioned at ultraviolet light photosensitive layer 23 carries out opto-electronic conversion, the light signal receiving is converted to the signal of telecommunication that comprises Pixel Information, because switch element 2312 is off-state (switch element grounded-grid) and switch element 2311 is conducting state (switch element grid connects high level), by the transfering transistor corresponding with PN junction photodiode 232 343, (its grid switches through shifting signal TX, its source electrode meets described PN junction photodiode 232NXing district, not shown) and floating diffusion region 353 be connected to the grid that transistor 32 is followed in described source, at described power supply V ddand under the effect of current source cell 13, the source electrode output packet of transistor 32 is followed containing the extremely drain electrode of described row selecting transistor 33 of the signal of telecommunication of Pixel Information in described source.
The grid of described row selecting transistor 33 meets row selection signal RS, and it drains as input connects the source electrode that transistor 32 is followed in described source, and wherein, source electrode is output.Described row selecting transistor 33 exports column bus 11 to for described source being followed to the signal of telecommunication that comprises Pixel Information of the source electrode output of transistor 32.
Simultaneously, selecting natural daylight is that light source is when expose, make it in off-state (being switch opens) grounded-grid of switch element 2211 and 2111, for providing high level, the grid of switch element 2212 and 2112 make it in conducting state (being that switch is closed), make the PN junction photodiode 222 and 212 of visible ray photosensitive layer 22 and infrared light photosensitive layer 21 correspondences obtain electric charge through opto-electronic conversion, by switch element 2212 and 2112, export to described energy-storage units 15.
Each photosensitive layer pixel sensing element 3 shared with it of described sensitization lamination 2 forms a picture element module 5, and a plurality of described picture element modules 5 form picture element module array 6 (not shown).The signal of telecommunication that comprises Pixel Information of each ultraviolet light photosensitive layer 23 of described picture element module array 6 transfers to graphics processing unit 14 via described pixel sensing element 3, described column bus 11 and amplifier 12, so that the described signal of telecommunication that comprises Pixel Information is carried out to image processing; The electric charge that each visible ray photosensitive layer 22 of described picture element module array 6 and infrared light photosensitive layer 21 obtain, by switch element 2212 and 2112, export to described energy-storage units 15, and be converted to suitable voltage and preserve by described power-switching circuit wherein, when needs self energizing, the voltage of preservation is connected to the required power supply V of pixel sensing element 3 dd, for described pixel sensing element 3 provides drain voltage V dd, for described cmos image sensor is realized self-supply power source function.
In like manner, in the present embodiment one, if only need read the signal of telecommunication that comprises Pixel Information of visible ray photosensitive layer 22 or infrared light photosensitive layer 21, and store infrared light photosensitive layer 21 and ultraviolet light photosensitive layer 23 simultaneously, or the electric charge of its corresponding photo-sensitive cell opto-electronic conversion in storage visible ray photosensitive layer 22 and ultraviolet light photosensitive layer 23, only need to adjust switch element 2211, 2112 and 2312 is conducting state (being that switch element grid adds high voltage) and Simultaneous Switching element 2212, 2111 and 2311 is off-state (being switch element grounded-grid), or adjustment switch element 2111, 2212 and 2312 is conducting state (being that switch element grid adds high voltage) and Simultaneous Switching element 2112, 2211 and 2311 is off-state (being switch element grounded-grid).
The invention provides a kind of self energizing cmos image sensor, adopted the design of free of light filter, the problems such as picture quality variation of also having avoided filter to cause when reducing costs, adopt the sensitization lamination of stacked structure, make required circuit structure can be made in (substrate layer) on independent one deck, thereby greatly improve fill factor, curve factor, further improve the quality of image, simultaneously, owing to adopting the sensitization lamination of stacked structure, make a pixel there is the ability that detects different-waveband light, single exposure can obtain ultraviolet light simultaneously, the information such as visible ray and infrared light, on the one hand, can obtain much information by chip piece, cost and complexity have not only been reduced, and efficiency and the picture quality of conversion have greatly been improved, on the other hand, when reading information needed, the residual charge that can selectively different photosensitive layers be produced saves, and provide power supply by power-switching circuit for whole imageing sensor, to realize self-energizing function, make full use of the energy of light, and strengthened the adaptive capacity of imageing sensor.
Embodiment bis-
Embodiment bis-and embodiment mono-adopt essentially identical technical scheme, the assembly that the self energizing cmos image sensor that to be embodiment bis-provide with embodiment mono-comprises, the relevant connection mode of inter-module and and operation principle basic identical, difference is that the self energizing cmos image sensor in embodiment bis-is 3T type, and pixel sensing element 3 ' is arranged in substrate layer, sensitization lamination 2 ' is for absorbing three photosensitive layers of three band of light, the first photosensitive layer is ruddiness photosensitive layer 21 ', the second photosensitive layer is green glow photosensitive layer 22 ', the 3rd photosensitive layer is blue light photosensitive layer 23 ', and respectively this photosensitive layer is silicon (Si) material.
It needs to be noted, the light of different wave length has different response characteristics in same semi-conducting material, semi-conducting material will absorb the light of different wave length, need different incident light paths, wavelength is shorter, absorb incident light completely, to realize effective light path that opto-electronic conversion needs incident light to transmit in semiconductor shorter, otherwise longer.For the ease of absorb the light of different-waveband simultaneously, make imageing sensor of the present invention there is the ability that detects different-waveband light, the present invention adopts laminated construction in order to light absorbing described sensitization lamination, because respectively this photosensitive layer residing position in sensitization lamination is different, therefore when respectively this photosensitive layer is semi-conducting material of the same race, also can absorb the light of different-waveband.For visible ray, because blue light, green glow and red light wavelength are for increasing progressively situation, therefore blue light absorption is in the region on the most close plane of incidence (surface of sensitization lamination), the absorption of ruddiness concentrates on apart from the plane of incidence (surface of sensitization lamination) interior zone far away, and the absorption region of green glow is between between the two.
Therefore,, in the present embodiment two, for absorbing, first photosensitive layer (ruddiness photosensitive layer 21 ') of the first band of light (ruddiness) is stacked covers described substrate layer 1, is positioned at the orlop of sensitization lamination 2 '; The second photosensitive layer (green glow photosensitive layer 22 ') that is used for absorbing the second band of light (green glow) is layered in described the first photosensitive layer (ruddiness photosensitive layer 21 '); The 3rd photosensitive layer (blue light photosensitive layer 23 ') that is used for absorbing triband light (blue light) is layered in described the second photosensitive layer (green glow photosensitive layer 22 '), is positioned at the superiors of sensitization lamination 2 '.
Equivalent circuit diagram Fig. 5 and the equivalent circuit diagram Fig. 1 in embodiment mono-in the present embodiment two are basic identical.Than the 4T type self energizing cmos image sensor in embodiment mono-, the pixel sensing element 3 ' of the 3T type self energizing cmos image sensor in embodiment bis-has lacked transfering transistor in embodiment mono-(TX) and floating diffusion region (FD); Pixel sensing element 3 in embodiment mono-is arranged in enforcement visible ray photosensitive layer 22, and the pixel sensing element 3 ' in embodiment bis-is arranged in substrate layer 1.Concrete difference is as follows:
Refer to Fig. 5, in the present embodiment two, self energizing cmos image sensor provided by the invention is 3T type, pixel sensing element 3 ' comprises that reset transistor 31 ', source follow transistor 32 ' and row selecting transistor 33 ', simultaneously in the present embodiment two, pixel sensing element is arranged in substrate layer 1, all photo-sensitive cells of described sensitization lamination 2 ' (PN junction photodiode 212 ', 222 ' and 232 ') share described pixel sensing element 3 ', wherein, described sensitization lamination 2 ' is a picture element module 5 '.
As shown in Figure 5, in the present embodiment two, respectively this switch element 2111 ' and 2112 ' that is positioned at described ruddiness photosensitive layer 21 ' is connected to PN junction photodiode 212 ' NXing district; Respectively this switch element 2211 ' and 2212 ' that is positioned at described green glow photosensitive layer 22 ' is connected to PN junction photodiode 222 ' NXing district; Respectively this switch element 2311 ' and 2312 ' that is positioned at described blue light photosensitive layer 23 ' is connected to PN junction photodiode 232 ' NXing district.
Further, as shown in Figure 5, in the present embodiment two, the source electrode of the reset transistor 31 ' of described pixel sensing element 3 ' and this switch element respectively 2111 ', one end of 2211 ' and 2311 ' are connected, and respectively this switch element 2111 ', 2211 ' and 2311 ' the other end and lay respectively at respectively in this photosensitive layer 21 ', 22 ', 23 ' photo-sensitive cell (PN junction photodiode 212 ', 222 ' and 232 ') NXing district separately and be connected; The grid that transistor 32 ' is followed in the source of described pixel sensing element 3 ' and each photo-sensitive cell (PN junction photodiode 212 ', 222 ' and 232 ') in described respectively this photosensitive layer separately NXing district are connected by this switch element 2111 ', 2211 ' and 2311 ' respectively respectively, and now the grid of transistor 32 ' is followed, the source electrode of reset transistor 31 ' is all connected with this switch element respectively 2111 ', one end of 2211 ' and 2311 ' in described source.
For further illustrating the operation principle of the present invention in embodiment bis-, refer to again Fig. 5, the signal of telecommunication that comprises Pixel Information, storage green glow photosensitive layer 22 ' and the ruddiness photosensitive layer 21 ' that only the read blue light photosensitive layer 23 ' electric charge by its photo-sensitive cell opto-electronic conversion separately of take is example, describes the operation principle of described self energizing cmos image sensor in the present embodiment two:
Selection natural daylight is light source, before exposure, when switch element 2312 ' is off-state (switch element grounded-grid) and switch element 2311 ' and is conducting state (switch element grid connects high level), for the reset signal Reset of described reset transistor 31 ' provides high level, described reset transistor 31 ' conducting, described PN junction photodiode 232 ' NXing district is connected to its drain power V by reset transistor 31 ' dd, at described power supply V ddeffect under, make described PN junction photodiode 232 ' partially anti-and remove the electric charge of whole accumulations of described PN junction photodiode 232 ', realize and resetting.
The drain electrode that transistor 32 ' is followed in described source meets described power supply V ddwhen described self energizing cmos image sensor is realized after reset, selecting natural daylight is that light source exposes, the photo-sensitive cell (PN junction photodiode 232 ') that is positioned at blue light photosensitive layer 23 ' carries out opto-electronic conversion, the light signal receiving is converted to the signal of telecommunication that comprises Pixel Information, because switch element 2312 ' is off-state (switch element grounded-grid) and switch element 2311 ' is conducting state (switch element grid connects high level), PN junction photodiode 232 ' NXing district is connected to the grid that transistor 32 ' is followed in described source, at described power supply V ddand under the effect of current source cell 13, the source electrode output packet of transistor 32 ' is followed containing the extremely drain electrode of described row selecting transistor 33 ' of the signal of telecommunication of Pixel Information in described source.
The grid of described row selecting transistor 33 ' meets row selection signal RS, and it drains as input connects the source electrode that transistor 32 ' is followed in described source, and wherein, source electrode is output.Described row selecting transistor 33 ' exports column bus 11 to for described source being followed to the signal of telecommunication that comprises Pixel Information of the source electrode output of transistor 32 '.
Simultaneously, selecting natural daylight is that light source is when expose, make it in off-state (being switch opens) grounded-grid of switch element 2211 ' and 2111 ', for providing high level, the grid of switch element 2212 ' and 2112 ' make it in conducting state (being that switch is closed), make the PN junction photodiode 222 ' and 212 ' that green glow photosensitive layer 22 ' and ruddiness photosensitive layer 21 ' are corresponding obtain electric charge through opto-electronic conversion, by switch element 2212 ' and 2112 ', export to described energy-storage units 15.
Each photosensitive layer of described sensitization lamination 2 ' and its pixel sensing element that is positioned at substrate layer 1 sharing 3 ' form a picture element module 5 ', and a plurality of described picture element modules 5 ' form picture element module array 6 ' (not shown).The signal of telecommunication that comprises Pixel Information of each blue light photosensitive layer 23 ' of described picture element module array 6 ' transfers to graphics processing unit 14 via described pixel sensing element 3 ', described column bus 11 and amplifier 12, so that the described signal of telecommunication that comprises Pixel Information is carried out to image processing; The electric charge that each green glow photosensitive layer 22 ' of described picture element module array 6 ' and ruddiness photosensitive layer 21 ' obtain, by switch element 2212 ' and 2112 ', export to described energy-storage units 15, and be converted to suitable voltage and preserve by described power-switching circuit wherein, when needs self energizing, the voltage of preservation is connected to the required power supply V of pixel sensing element 3 ' dd, for described pixel sensing element 3 ' provides drain voltage V dd, for described cmos image sensor is realized self-supply power source function.
In like manner, in the present embodiment two, if only need read the signal of telecommunication that comprises Pixel Information of green glow photosensitive layer 22 ' or ruddiness photosensitive layer 21 ', and store ruddiness photosensitive layer 21 ' and blue light photosensitive layer 23 ' simultaneously, or the electric charge of its corresponding photo-sensitive cell opto-electronic conversion in storage green glow photosensitive layer 22 ' and blue light photosensitive layer 23 ', only need to adjust switch element 2211 ', 2112 ' and 2312 ' is conducting state (being that switch element grid adds high voltage) and Simultaneous Switching element 2212 ', 2111 ' and 2311 ' is off-state (being switch element grounded-grid), or adjustment switch element 2111 ', 2212 ' and 2312 ' is conducting state (being that switch element grid adds high voltage) and Simultaneous Switching element 2112 ', 2211 ' and 2311 ' is off-state (being switch element grounded-grid).
In sum, the invention provides a kind of self energizing cmos image sensor, adopted the design of free of light filter, the problems such as picture quality variation of also having avoided filter to cause when reducing costs, adopt the sensitization lamination of stacked structure, make required circuit structure can be made in (substrate layer) on independent one deck, thereby greatly improve fill factor, curve factor, further improve the quality of image, simultaneously, owing to adopting the sensitization lamination of stacked structure, make a pixel there is the ability that detects different-waveband light, single exposure can obtain blue light simultaneously, the information such as green glow and ruddiness, on the one hand, can obtain much information by chip piece, cost and complexity have not only been reduced, and efficiency and the picture quality of conversion have greatly been improved, on the other hand, when reading information needed, the residual charge that can selectively different photosensitive layers be produced saves, and provide power supply by power-switching circuit for whole imageing sensor, to realize self-energizing function, make full use of the energy of light, and strengthened the adaptive capacity of imageing sensor.Self energizing cmos image sensor provided by the invention, can be positioned at red, blue, the preparation of green glow sensor devices on the different laminations of Semiconductor substrate the same area in order to realize the accurate imaging of visible ray, has further improved the integrated level of imageing sensor.So the present invention has effectively overcome various shortcoming of the prior art and tool high industrial utilization.
Above-described embodiment is illustrative principle of the present invention and effect thereof only, but not for limiting the present invention.Any person skilled in the art scholar all can, under spirit of the present invention and category, modify or change above-described embodiment.Therefore, such as in affiliated technical field, have and conventionally know that the knowledgeable, not departing from all equivalence modifications that complete under disclosed spirit and technological thought or changing, must be contained by claim of the present invention.

Claims (12)

1. a self energizing cmos image sensor, is characterized in that, at least comprises:
Substrate layer, at least comprise the column bus that is positioned at wherein, amplifier, in order to provide the current source cell of constant current, the graphics processing unit of processing in order to image and for the energy-storage units of self-supply power source, wherein, described graphics processing unit at least comprises clock and control circuit, row, column, layer decoder circuit, sampling hold circuit, analog to digital converter, image processor; Described energy-storage units comprises charge storage circuit and power-switching circuit, so that the electric charge of storage is converted to suitable voltage by described power-switching circuit, for described cmos image sensor provides power supply; Described amplifier is all connected with column bus with current source cell;
Sensitization lamination, the described substrate layer of stacked covering surface, in order to absorb the light of different-waveband simultaneously, at least comprise stacked cover on described substrate layer for absorbing respectively a plurality of photosensitive layers of this different-waveband light, and respectively in this photosensitive layer, at least comprise two switch elements and be connected in a photo-sensitive cell between these two switch elements;
Pixel sensing element, be arranged in substrate layer or be arranged at least one photosensitive layer of described sensitization lamination, at least comprise connect the reset transistor of described photosensitive layer, transistor is followed in the source that connects described reset transistor and photosensitive layer, and connect described source and follow transistorized row selecting transistor; Wherein, in the time of in a plurality of photosensitive layers of the sensitization lamination described in a plurality of described pixel sensing elements lay respectively at, a plurality of pixel sensing elements described in all photo-sensitive cell correspondences of described sensitization lamination, and each photo-sensitive cell of described sensitization lamination is only connected with a described pixel sensing element by its each self-corresponding switch element, wherein, described sensitization lamination and a plurality of described pixel sensing element form a picture element module.
2. self energizing cmos image sensor according to claim 1, is characterized in that: described sensitization lamination at least comprise stacked cover on described substrate layer for absorb the first photosensitive layer of the first band of light and be layered on described the first photosensitive layer for absorbing the second photosensitive layer of the second band of light.
3. self energizing cmos image sensor according to claim 2, is characterized in that: described sensitization lamination also comprise be layered on described the second photosensitive layer for absorbing the 3rd photosensitive layer of triband light.
4. self energizing cmos image sensor according to claim 3, it is characterized in that: in described the first photosensitive layer, by germanium is adulterated, form in order to absorb the germanium material photo-sensitive cell of infrared light, in described the second photosensitive layer, by silicon is adulterated, form in order to absorb the silicon materials photo-sensitive cell of visible ray, in described the 3rd photosensitive layer, by carborundum is adulterated, form in order to absorb the carbofrax material photo-sensitive cell of ultraviolet light.
5. self energizing cmos image sensor according to claim 1, it is characterized in that: respectively the material of this photosensitive layer is the photon energy of energy gap and the required absorption semi-conducting material that matches, be selected from respectively carborundum, silicon, germanium or germanium silicon, or be selected from respectively carborundum, silicon, germanium or germanium silicon through doping.
6. self energizing cmos image sensor according to claim 1, is characterized in that: respectively this photosensitive layer in described sensitization lamination is semi-conducting material of the same race.
7. self energizing cmos image sensor according to claim 1, is characterized in that: between described substrate layer and sensitization lamination, have in insulating barrier and/or described sensitization lamination and have insulating barrier between each photosensitive layer.
8. self energizing cmos image sensor according to claim 1, is characterized in that: the compound photosensitive layer of the photosensitive layer in described sensitization lamination for being comprised of a plurality of sensitization sublayer.
9. self energizing cmos image sensor according to claim 8, is characterized in that: respectively between this sensitization sublayer, have insulating barrier.
10. self energizing cmos image sensor according to claim 1, is characterized in that: respectively this photo-sensitive cell of described sensitization lamination is at least one in PN junction photodiode, pinprick formula photodiode or photoelectricity door.
11. self energizing cmos image sensors according to claim 1, it is characterized in that: described pixel sensing element is arranged in a photosensitive layer of described sensitization lamination, all photo-sensitive cells of described sensitization lamination share described pixel sensing element, and respectively between this photo-sensitive cell and described pixel sensing element, by the switch element that respectively this photo-sensitive cell is corresponding, connect, wherein, described sensitization lamination and pixel sensing element form a picture element module.
12. self energizing cmos image sensors according to claim 1, it is characterized in that: described pixel sensing element is arranged in substrate layer, all photo-sensitive cells of described sensitization lamination share described pixel sensing element, and wherein, described sensitization lamination is a picture element module.
CN201210113012.6A 2012-04-17 2012-04-17 Self-powered CMOS (Complementary Metal-Oxide-Semiconductor Transistor) image sensor Active CN102623476B (en)

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