CN207781597U

CN207781597U - A kind of cmos image sensor for improving white pixel

Info

Publication number: CN207781597U
Application number: CN201721592960.7U
Authority: CN
Inventors: 王骞; 秋沉沉; 曹亚民
Original assignee: Shanghai Huali Microelectronics Corp
Current assignee: Shanghai Huali Microelectronics Corp
Priority date: 2017-11-24
Filing date: 2017-11-24
Publication date: 2018-08-28
Anticipated expiration: 2027-11-24

Abstract

The utility model provides a kind of cmos image sensor for improving white pixel, and the control using 4T structures and transmission circuit, the cmos image sensor include photodiode, and the photoelectric diode upper surface is provided with polysilicon layer.The utility model is directed to the insufficient problem of the isolation brought using p-type doping isolation photodiode and oxide interface in existing cmos image sensor.In the utility model on the basis of existing cmos image sensor CIS, additional polysilicon design is added, and back bias voltage is applied to the polysilicon region within the CIS working times, using the method electrically isolated, influence of the oxide interface state to photodiode is reduced, to reduce the noises such as white pixel, to make original fixed oxide layer isolation effect, become adjustable isolation effect, meets different isolation requirements.

Description

A kind of cmos image sensor for improving white pixel

Technical field

The utility model is related to a kind of semiconductor equipment more particularly to a kind of cmos image sensings for improving white pixel Device.

Background technology

As depicted in figs. 1 and 2, existing metal oxide semiconductor device (CMOS, Complementary Metal- Oxide Semiconductor) in imaging sensor, photodiode is mainly adulterated using relatively thin p-type with oxide interface It is isolated, the noises such as white pixel caused by reduce interfacial state.The defect of this method is that wider separation layer can cause full Trap capacitance reduces, and transition occurs for electronics in relatively narrow separation layer or compound probability is still larger, can not effectively reduce noise, together When fixed due to spacer width, isolation requirement under different use conditions can not be coped with.

Utility model content

Technical problem to be solved in the utility model be in view of the drawbacks of the prior art, provide one kind can effectively improve it is white The cmos image sensor of pixel.

The utility model uses following technical scheme to solve above-mentioned technical problem：

A kind of cmos image sensor for improving white pixel, the control using 4T structures and transmission circuit, it is described Cmos image sensor includes photodiode, and the photoelectric diode upper surface is provided with polysilicon layer.

In order to advanced optimize above-mentioned technical proposal, the technical measures that the utility model is taken are：

Preferably, the gate oxide of the photodiode surface covering general thickness.

It is furthermore preferred that covering trapezoidal or triangle polysilicon layer above the gate oxide.

Preferably, the polysilicon layer is adulterated using p-type.

Preferably, the polysilicon layer interconnection or mutually isolated of the photodiode upper surface.

Preferably, the polysilicon layer is by the way that shared or individually contact hole carries out electrical interconnection with external circuitry.

Preferably, the cmos image sensor further includes reset transistor.

Preferably, the cmos image sensor further includes source follower.

Preferably, the cmos image sensor further includes row selector.

The utility model is had the following technical effect that compared with prior art using above technical scheme：

The utility model is directed in existing cmos image sensor using p-type doping isolation photodiode and oxidation stratum boundary What face was brought is isolated insufficient problem.In existing CMOS contact-type image sensors (CIS, Contact Image in the present invention Sensor on the basis of), additional polysilicon design is added, and negative bias is applied to the polysilicon region within the CIS working times Pressure is reduced influence of the oxide interface state to photodiode, is made an uproar to reduce white pixel etc. using the method electrically isolated Sound becomes adjustable isolation effect, meets different isolation requirements to make original fixed oxide layer isolation effect.

Description of the drawings

Fig. 1 is the sectional view of existing cmos image sensor；

Fig. 2 is the vertical view of existing cmos image sensor；

Fig. 3 is a kind of sectional view of the cmos image sensor of preferred embodiment of the utility model；

Fig. 4 is a kind of vertical view of the cmos image sensor of preferred embodiment of the utility model；

Reference numeral therein is：

1 photoelectric diode；2 polysilicon layers；3 gate oxides；4 separation layers；5 transfer tubes.

Specific implementation mode

The technical solution of the utility model is described in further detail below in conjunction with the accompanying drawings.

Fig. 1 is the sectional view of existing cmos image sensor；Fig. 2 is the vertical view of existing cmos image sensor；Fig. 3 is A kind of sectional view of the cmos image sensor of the preferred embodiment of the utility model；Fig. 4 is that one kind of the utility model is preferred The vertical view of the cmos image sensor of embodiment.

It should be noted that in the absence of conflict, the feature in the embodiments of the present invention and embodiment can To be combined with each other.

As shown in Figures 3 and 4, the cmos image sensor for improving white pixel of the present embodiment, using the control of 4T structures System and transmission circuit, the cmos image sensor include photodiode 1, and the photoelectric diode upper surface is provided with polycrystalline Silicon layer 2.

Further, in a kind of preferred embodiment, 1 upper surface of the photoelectric diode is provided with separation layer 4；

Further, in a kind of preferred embodiment, 1 upper surface of the photoelectric diode is provided with transfer tube 5；

Further, in a kind of preferred embodiment, 1 surface of the photodiode covers the gate oxidation of general thickness Layer 3.

Further, in a kind of preferred embodiment, 1 upper surface of the photoelectric diode is disposed with from top to bottom Separation layer 4, gate oxide 3 and polysilicon layer 2.

Further, in a kind of preferred embodiment, 3 top of the gate oxide covers trapezoidal or triangle polycrystalline Silicon layer 2.

Further, in a kind of preferred embodiment, the polysilicon layer 2 is adulterated using p-type.

Further, in a kind of preferred embodiment, 2 phase of polysilicon layer of 1 upper surface of the photodiode interconnects It connects or mutually isolated.

Further, in a kind of preferred embodiment, the polysilicon layer 2 is by shared or individual contact hole and outside Boundary's circuit carries out electrical interconnection.

Further, in a kind of preferred embodiment, the cmos image sensor further includes reset transistor.

Further, in a kind of preferred embodiment, the cmos image sensor further includes source follower.

Further, in a kind of preferred embodiment, the cmos image sensor further includes row selector.

The specific works method of the cmos image sensor for improving white pixel of the utility model is：

On the basis of existing cmos image sensor, additional polysilicon layer is set in the upper surface of photodiode 1 2, polysilicon layer 2 is set in 1 upper surface of photodiode of 4T types, each rectangle or square upper surface are provided with by center Polysilicon layer 2, the polysilicon layer is arranged in the transfer tube 5 of the triangle of point, the upper surface outside the transfer tube 5 of the triangle 2 without departing from the rectangle or square upper surface surrounding, and is disposed adjacent in 1 upper table of photodiode with the transfer tube 5 Face；The photodiode 1 is disposed with separation layer 4, gate oxide 3 from top to bottom in the region for being provided with polysilicon layer 2 With polysilicon layer 2.The polysilicon layer 2 applies back bias voltage within the CIS working times to the region of the polysilicon layer 2, using electricity The method of sexual isolation reduces influence of 3 interfacial state of gate oxide to photodiode.

In conclusion photodiode is isolated using p-type doping in existing cmos image sensor in the utility model Insufficient problem is isolated with what oxide interface was brought.In the present invention existing CMOS contact-type image sensors (CIS, Contact Image Sensor) on the basis of, additional polysilicon design is added, and to the polycrystalline within the CIS working times Silicon area applies back bias voltage, using the method electrically isolated, influence of the oxide interface state to photodiode is reduced, to drop The noises such as low white pixel become adjustable isolation effect to make original fixed oxide layer isolation effect, meet different Isolation requirement.

Specific embodiment of the utility model is described in detail above, but it is only used as example, the utility model It is not restricted to particular embodiments described above.To those skilled in the art, any that the practicality is equal Modifications and substitutions are also all among the scope of the utility model.Therefore, the institute under the spirit and scope for not departing from the utility model The impartial conversion of work and modification should all be covered in the scope of the utility model.

Claims

1. a kind of cmos image sensor for improving white pixel, it is characterised in that：Control using 4T structures and transmission electricity Road, the cmos image sensor include photodiode (1), and the photoelectric diode upper surface is provided with polysilicon layer (2)； The gate oxide (3) of photodiode (1) the surface covering general thickness；Above the gate oxide (3) covering it is trapezoidal or The polysilicon layer (2) of triangle；The polysilicon layer (2) is adulterated using p-type.

2. the cmos image sensor according to claim 1 for improving white pixel, it is characterised in that：The photoelectricity two Polysilicon layer (2) interconnection or mutually isolated of pole pipe (1) upper surface.

3. the cmos image sensor according to claim 1 for improving white pixel, it is characterised in that：The polysilicon Layer (2) is by the way that shared or individually contact hole carries out electrical interconnection with external circuitry.

4. the cmos image sensor according to claim 1 for improving white pixel, it is characterised in that：The CMOS figures As sensor further includes reset transistor.

5. the cmos image sensor according to claim 1 for improving white pixel, it is characterised in that：The CMOS figures As sensor further includes source follower.

6. the cmos image sensor according to claim 1 for improving white pixel, it is characterised in that：The CMOS figures As sensor further includes row selector.