CN203812881U - Image sensor pixel structure capable of preventing image diffusion - Google Patents
Image sensor pixel structure capable of preventing image diffusion Download PDFInfo
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- CN203812881U CN203812881U CN201420120647.3U CN201420120647U CN203812881U CN 203812881 U CN203812881 U CN 203812881U CN 201420120647 U CN201420120647 U CN 201420120647U CN 203812881 U CN203812881 U CN 203812881U
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- photodiode
- trench isolation
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- transistor drain
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- 229910044991 metal oxide Inorganic materials 0.000 description 1
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- 239000011241 protective layer Substances 0.000 description 1
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Abstract
The utility model discloses an image sensor pixel structure capable of preventing image diffusion. A shallow slot isolation region at one side of a photodiode of the image sensor pixel structure, one of two shallow slot isolation regions at the other side, and a transistor drain terminal portion active region are all provided with deep P-type well regions, wherein the deep P-type well region of the transistor drain terminal active region covers the shallow slot isolation region far away from the photodiode and is not contacted with the shallow slot isolation region close to the photodiode so that an overflowing charge conducting channel is formed between the photodiode and the transistor drain terminal active region. By adopting the image sensor pixel structure, diffusion phenomenon of acquired images can be prevented, and color distortion of surrounding pixel of high light images can be eliminated.
Description
Technical field
The utility model relates to technical field of manufacturing semiconductors, relates in particular to a kind of image sensor pixel structure of the figure of preventing image confusion.
Background technology
Imageing sensor has been widely used in digital camera, cell phone, medicine equipment, automobile and other application scenarios.Particularly manufacture CMOS(CMOS (Complementary Metal Oxide Semiconductor)) fast development of image sensor technologies, make people have higher requirement to the output image quality of imageing sensor.
Image sensor chip of the prior art, the bright spot or the bright line region that are collected in image can be greater than actual image size.For example, while containing the luminous strong sun, auto bulb, incandescent lamp or reflective strong light image in the photograph of taking pictures, these image can be greater than actual size, and the light regions such as the sun and light become than large many of actual size, and this phenomenon is called as figure image confusion in image field.
Imageing sensor of the prior art, taking cmos image sensor four transistor pixel structures as example, as shown in Figure 1.In Fig. 1,101～105 is photodiode adjacent to one another, and TX1 and TX2 are charge pass transistor, and RX1 and RX2 are reset transistor, and SF1 and SF2 are that transistor is followed in source, and SX1 and SX2 are row selecting transistor; CT11, CT12 and CT21, CT22 are transistor active area contact hole, and wherein CT11 and CT21 and positive source interconnect.As shown in Figure 2, in the device in P type silicon substrate, 201～203 is adjacent photodiode to the sectional drawing of the tangent position of dotted line shown in Fig. 1, and 204 are transistor drain terminal active area and are connected with power supply, and 205 is the P(positive) type well region, 206 is P+ layer.
The defect that technique scheme exists is:
When photodiode 201 is subject to strong illumination, photodiode 201 trap internal cause electric charges too completely spill in P type silicon substrate, what overflow cross multi-charge and can walk around P type well region 205 and float in photodiode 202 and 203 traps that close on, and photodiode 202 and 203 has been subject to 201 electric charge and crosstalks; When photodiode 202 or 203 because the electric charge of photodiode 201 is crosstalked after saturated, the photodiode on the photodiode in photodiode 202 left sides or photodiode 203 right sides also can be subject to the electric charge of photodiode 202 or 203 and crosstalk, and then disperse is come.The picture element signal that makes to be crosstalked can not be reflected true illumination by this, causes that saturated pixel quantity increases than actual, and can cause color of image distortion, and image diffusing phenomenon occurs.Therefore, there is the imageing sensor of image diffusing phenomenon, can not correctly collect the object information that high light object closes on, thereby reduced the quality of image.
Utility model content
The purpose of this utility model is to provide a kind of image sensor pixel structure of the figure of preventing image confusion, prevents that the image gathering from producing diffusing phenomenon, eliminates the problem of the surrounding pixel cross-color of high light image simultaneously.
The purpose of this utility model is achieved through the following technical solutions:
A kind of image sensor pixel structure that prevents figure image confusion, at least comprise the photodiode that is placed in semiconductor substrate, be arranged at a shallow trench isolation region of this photodiode one side, be arranged at two shallow trench isolation regions of this photodiode opposite side and be arranged between described two shallow trench isolation regions and the transistor drain terminal active area being connected with power supply, wherein, one shallow trench isolation region of described photodiode one side, on shallow trench isolation region in two shallow trench isolation regions of opposite side and transistor drain terminal part active area, be equipped with dark P type well region, wherein, dark P type well region on described transistor drain terminal part active area, it covers apart from described photodiode shallow trench isolation region far away, and with apart from the nearer shallow trench isolation region of described photodiode do not contact, make to form and overflow electric charge flow-guiding channel between described photodiode and transistor drain terminal active area.
Further, the degree of depth of described dark P type well region is not less than 2.5 μ m.
The technical scheme being provided by above-mentioned the utility model can be found out, by adopting dark P trap Implantation, makes to form the excessive passage of electric charge between photodiode and transistor drain terminal active area.Therefore, excessive electric charge when imageing sensor photodiode is saturated, can be guided to transistor drain terminal active area by the excessive passage of this electric charge, and then be absorbed by power supply, and can not be crosstalked in the photodiode of adjacent pixels; Thereby can prevent the generation of image diffusing phenomenon, eliminate the problem of the surrounding pixel cross-color of high light image simultaneously.
Brief description of the drawings
In order to be illustrated more clearly in the technical scheme of the utility model embodiment, below the accompanying drawing of required use during embodiment is described is briefly described, apparently, accompanying drawing in the following describes is only embodiment more of the present utility model, for those of ordinary skill in the art, do not paying under the prerequisite of creative work, can also obtain other accompanying drawings according to these accompanying drawings.
Four transistor pixel structure floor map of the existing cmos image sensor that Fig. 1 provides for the utility model background technology;
The photodiode of the existing cmos image sensor that Fig. 2 provides for the utility model background technology and tangent plane schematic diagram around thereof;
Photodiode and tangent plane schematic diagram around thereof in the image sensor pixel structure of a kind of figure of preventing image confusion that Fig. 3 provides for the utility model embodiment mono-;
In the image sensor pixel structure manufacture method of a kind of figure of preventing image confusion that Fig. 4 provides for the utility model embodiment mono-, generate the schematic diagram of protect oxide layer layer step;
The schematic diagram of spin coating photoresist development step for the first time in the image sensor pixel structure manufacture method of a kind of figure of preventing image confusion that Fig. 5 provides for the utility model embodiment mono-;
The schematic diagram of dark P type trap Implantation step in the image sensor pixel structure manufacture method of a kind of figure of preventing image confusion that Fig. 6 provides for the utility model embodiment mono-;
In the image sensor pixel structure manufacture method of a kind of figure of preventing image confusion that Fig. 7 provides for the utility model embodiment mono-, remove the schematic diagram of photoresist step.
Embodiment
Below in conjunction with the accompanying drawing in the utility model embodiment, the technical scheme in the utility model embodiment is clearly and completely described, obviously, described embodiment is only the utility model part embodiment, instead of whole embodiment.Based on embodiment of the present utility model, those of ordinary skill in the art, not making the every other embodiment obtaining under creative work prerequisite, belong to protection range of the present utility model.
Embodiment mono-
The utility model embodiment provides a kind of image sensor pixel structure of the figure of preventing image confusion, at least comprise the photodiode that is placed in semiconductor substrate, be arranged at a shallow trench isolation region of this photodiode one side, be arranged at two shallow trench isolation regions of this photodiode opposite side and be arranged between described two shallow trench isolation regions and the transistor drain terminal active area being connected with power supply, wherein, one shallow trench isolation region of described photodiode one side, on a shallow trench isolation region in two shallow trench isolation regions of opposite side and described transistor drain terminal part active area (all not covering), be equipped with dark P type well region, wherein, dark P type well region on described transistor drain terminal active area, it covers apart from described photodiode shallow trench isolation region far away, and with apart from the nearer shallow trench isolation region of described photodiode do not contact, make to form and overflow electric charge flow-guiding channel between described photodiode and transistor drain terminal active area.
Further, the degree of depth of described dark P type well region is not less than 2.5 μ m.
In embodiment of the present utility model, image sensor pixel structure is applicable to four transistors, five transistors, six transistors and seven transistor pixels, photodiode in dot structure is applicable to Pin type N-type photodiode, Pin type P type photodiode, part Pin type photodiode, polysilicon gate type photodiode, and comprise front according to two types of formula cmos image sensor and back-illuminated cmos image sensors; Also be applicable to CCD(charge coupled device simultaneously) imageing sensor.
For convenience of explanation, the present embodiment image taking sensor four transistor pixel structures, photodiode adopts Pin type N-type photodiode, and it is that example is introduced that the transistor in pixel adopts N-type transistor.
Photodiode and tangent plane schematic diagram around thereof in the image sensor pixel structure of a kind of figure of the preventing image confusion providing for the utility model embodiment as shown in Figure 3; Its tangent plane is the tangent plane of dotted line tangent position shown in Fig. 1.
In Fig. 3, semiconductor substrate is P type silicon substrate, and 301,302 and 303 is the photodiode region of closing on mutually, 304 is transistor drain terminal active area, and is connected with power supply Vdd, and 305 is dark P type well region, 306 is P+ layer, and STI is the shallow trench isolation region in CMOS traditional handicraft.
Wherein, the degree of depth of dark P type well region 305 is at least 2.5 μ m; And in transistor drain terminal active area part, dark 305 of P type well regions have occupied a part, and (occupying region can determine according to actual conditions, but not all cover) 304th district, transistor drain terminal active area, be that dark P type well region 305th district at least will cover the district away from described photodiode STI, dark P type well region 305 can not contact with close described photodiode STI district at most.In Fig. 3, can find out, due to dark not covering transistor drain terminal active area 304 left side one sides of P type well region 305, and the P type ion concentration that does not cover P type trap part is lower than P type well region P type ion concentration, so the potential barrier in dark P type well region 305 left sides is lower than dark P type well region 305; Owing to 304 being transistor drain terminal active area, this active area is N+ injection region, and Vdd is connected with power supply, so the potential barrier in the region between transistor drain terminal active area 304 bottom left sections and photodiode 301 all can be lower than the dark P type well region 305 of photodiode 301 both sides.Therefore, charge shift excessive when photodiode 301 is saturated is near the close STI of described photodiode, under the effect of transistor drain terminal active area 304 electrical source voltages, be easy to be drawn by transistor drain terminal active area 304, and then absorbed by power supply, so excessive electric charge is difficult to walk around dark P type well region 305 barrier regions and floats to photodiode 302 or photodiode 303.
In the utility model embodiment Fig. 3, transistor drain terminal active area 304 lower-left sides, dark P type well region 305 left sides, and near the low barrier region forming between the STI of described photodiode, be the electric charge flow-guiding channel that overflows described in the utility model, the existence of this passage, has prevented photodiode 302 or photodiode 303 that photodiode 301 closes on because saturated excessive electric charge is crosstalked into.
Further, for the ease of understanding the utility model, elaborate for its manufacture method below.Specifically refer to Fig. 4～Fig. 7, it mainly comprises the steps:
1) as shown in Figure 4, after the STI technique in traditional cmos process, the layer of oxide layer of growing on semiconductor-based surface 401 is as technique protective layer, and its thickness is 10nm～12nm, and the present embodiment adopts P type silicon substrate.
2) as shown in Figure 5, spin coating photoresist, and develop, at predetermined P type trap injection region opening; The thickness of photoresist, is not less than 2.7 μ m.Describedly comprise at predetermined P type trap injection region opening: an opening is the shallow trench isolation region to photodiode one side just, another opening covers shallow trench isolation region and the part active area away from described photodiode, and does not contact with the shallow trench isolation region near described photodiode.
3) as shown in Figure 6, semiconductor P type Implantation (for example, boron ion), adopts twice injection; Ion implantation energy is 500keV～600keV for the first time, and implantation dosage is 2.8e12 ion/square centimeter～3.2e12 ion/square centimeter; Ion implantation energy is greater than 900keV for the second time, and implantation dosage is at least 3e12 ion/square centimeter; The dark P type well depth degree forming is not less than 2.5 μ m.
4) as shown in Figure 7, after dark P type trap Implantation, remove photoresist, obtain the image sensor pixel structure that prevents figure image confusion.
In addition, the dark P type trap of the present embodiment also can use other ion implantation energy and dosage, as long as can form excessive electric charge flow-guiding channel; And dark P type trap is positioned at transistor drain terminal active area left part, excessive electric charge flow-guiding channel is formed at subregion, right side, active area, and this flow-guiding channel works to right side photodiode.
The utility model embodiment, by adopting dark P trap Implantation, makes to form the excessive passage of electric charge between photodiode and transistor drain terminal active area.Therefore, excessive electric charge when imageing sensor photodiode is saturated, can be guided to transistor drain terminal active area by the excessive passage of this electric charge, and then be absorbed by power supply, and can not be crosstalked in the photodiode of adjacent pixels; Thereby can prevent the generation of image diffusing phenomenon, eliminate the problem of the surrounding pixel cross-color of high light image simultaneously.
The above; it is only preferably embodiment of the utility model; but protection range of the present utility model is not limited to this; any be familiar with those skilled in the art the utility model disclose technical scope in; the variation that can expect easily or replacement, within all should being encompassed in protection range of the present utility model.Therefore, protection range of the present utility model should be as the criterion with the protection range of claims.
Claims (2)
1. one kind prevents the image sensor pixel structure of figure image confusion, at least comprise the photodiode that is placed in semiconductor substrate, be arranged at a shallow trench isolation region of this photodiode one side, be arranged at two shallow trench isolation regions of this photodiode opposite side and be arranged between described two shallow trench isolation regions and the transistor drain terminal active area being connected with power supply, it is characterized in that, one shallow trench isolation region of described photodiode one side, on shallow trench isolation region in two shallow trench isolation regions of opposite side and transistor drain terminal part active area, be equipped with dark P type well region, wherein, dark P type well region on described transistor drain terminal part active area, it covers apart from described photodiode shallow trench isolation region far away, and with apart from the nearer shallow trench isolation region of described photodiode do not contact, make to form and overflow electric charge flow-guiding channel between described photodiode and transistor drain terminal active area.
2. image sensor pixel structure according to claim 1, is characterized in that, the degree of depth of described dark P type well region is not less than 2.5 μ m.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201420120647.3U CN203812881U (en) | 2014-03-17 | 2014-03-17 | Image sensor pixel structure capable of preventing image diffusion |
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| CN201420120647.3U CN203812881U (en) | 2014-03-17 | 2014-03-17 | Image sensor pixel structure capable of preventing image diffusion |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103824869A (en) * | 2014-03-17 | 2014-05-28 | 北京思比科微电子技术股份有限公司 | Image sensor pixel structure for preventing image diffusion and manufacturing method thereof |
| CN107302008A (en) * | 2017-06-06 | 2017-10-27 | 上海集成电路研发中心有限公司 | Strengthen the back-illuminated type pixel cell structure and forming method of near-infrared photosensitive property |
-
2014
- 2014-03-17 CN CN201420120647.3U patent/CN203812881U/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103824869A (en) * | 2014-03-17 | 2014-05-28 | 北京思比科微电子技术股份有限公司 | Image sensor pixel structure for preventing image diffusion and manufacturing method thereof |
| CN107302008A (en) * | 2017-06-06 | 2017-10-27 | 上海集成电路研发中心有限公司 | Strengthen the back-illuminated type pixel cell structure and forming method of near-infrared photosensitive property |
| CN107302008B (en) * | 2017-06-06 | 2020-01-10 | 上海集成电路研发中心有限公司 | Back-illuminated pixel unit structure for enhancing near-infrared photosensitive property and forming method |
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