CN202816945U

CN202816945U - CMOS image sensor structure

Info

Publication number: CN202816945U
Application number: CN 201220064147
Authority: CN
Inventors: 陈多金; 赵文霖; 旷章曲
Original assignee: Beijing Superpix Micro Technology Co Ltd
Current assignee: Beijing Superpix Micro Technology Co Ltd
Priority date: 2012-02-23
Filing date: 2012-02-23
Publication date: 2013-03-20
Anticipated expiration: 2022-02-23

Abstract

The utility model provides a CMOS image sensor structure, comprising a high reflectivity film, two layers of metal connecting lines and a color filer array. The high reflectivity film used for shielding incident lights is arranged on the periphery and the top of the two layers of metal connecting lines; the color filer array is arranged in a photosensitive channel of the CMOS image sensor structure. The CMOS image sensor structure can effectively guide incident lights to the surface of a photodiode so as to improve sensitivity and quantum efficiency of the photodiode; the photosensitive channel and flat layers can effectively inhibit incident light refraction in a medium outside the channel so as to shield light crosstalk; the CMOS image sensor structure replaces traditional structure medium materials with CFA materials, which can avoid reflection of the incident lights caused by a medium refractive index.

Description

A kind of cmos image sensor structure

Technical field

The utility model relates to a kind of cmos image sensor dot structure, belongs to the image sensor technologies field.

Background technology

The extensive use of modern imageing sensor is ordered about cmos image sensor to more and more less size development.Along with dwindling of Pixel Dimensions, the parameters such as closely-related light sensitive diode electric capacity, sensitivity, quantum efficiency are faced with stern challenge with it.Therefore, so that method or equipment that light can more effectively be absorbed by light sensitive diode become one of key factor of small-sized pixel image quality.

Traditional cmos image sensor (take the dot structure of three-layer metal as example) as shown in Figure 1, form photodiode 102 at P type backing material 100 by traditional integrated circuit fabrication process such as photoetching, Implantation, corrosion and diffusion, isolate with shallow trench isolation (STI) 101 structures between the photodiode 102.Metal wire by sputtering technology formation control signal on photodiode 102.Form dielectric layer as metal and metal by chemical vapor deposition (CVD) technique, the separator of metal and silicon.Photodiode 102 surfaces dielectric layer from bottom to top is an ILD-Si ₃

N

₄103a, the 2nd ILD-SiO ₂103b, an IMD105, the 2nd IMD107, the 3rd IMD109a and passivation layer-Si ₃

N

₄109b, wherein passivation layer-Si ₃

N

₄109b has two effects: the one, and the protection surface, the 2nd, as the colorful optical filter array 111a that mentions hereinafter and the flatness layer of 111b.Distributing between dielectric layer and controlling metal wire the one metal106, the 2nd metal108, the 3rd metal110 of photodiode 102 normal operation, wherein a metal106 is connected by the device of formation on contact hole 104 and the P type epitaxial loayer 100.The important part of imageing sensor another one is colorful optical filter array (color filterarray) 111a and 111b, its effect is that incident light is resolved into three kinds of basic monochromatic light of red, green, blue, is lenticule (micro lens) 112 on colorfilter array.

The incident light of traditional imageing sensor is at the larger optically denser medium Si of refractive index ₃N ₄The optically thinner medium SiO that 109b and refractive index are less ₂During the interface of 109a, total reflection will occur incident light, and (refractive index of Color filter material is about 1.5, dielectric material SiO ₂Refractive index is about 1.45, Si ₃N ₄Refractive index is about 2.0), thus the utilance of incident light affected.Secondly, the conventional image sensor dielectric thickness total from lenticule (micro lens) 112 bottoms to the upper surface of photodiode 102 is about more than 2 microns, so long path channels is unfavorable for that incident light effectively arrives the pixel surface, and traditional image sensor architecture can't avoid incident light to arrive metal surface or side, causes through adjacent photodiode 102 surfaces of the final arrival of metallic reflection such as the incident light 103 among Fig. 1 and crosstalks.In addition, dielectric layer (ILD-SiO ₂103b, an IMD105, the 2nd IMD107 and the 3rd IMD109a) although all be SiO ₂Material, but in the integrated circuit technology processing procedure of reality, the deposit of dielectric layer usually adopts different chemical vapor depositions (CVD) equipment and method to finish, such as plasma chemical vapor deposition (PECVD), low-temperature gaseous phase chemical deposition (LPCVD) etc., therefore dielectric layer is actual is a kind of special composite bed, there is small difference in refractive index in the layer, and reflection in various degree can occur when incident light process composite bed.

Summary of the invention

The utility model provides a kind of Novel CMOS picture sensor structure, and this structure can effectively guide to incident light the surface of photodiode, thereby has improved sensitivity and the quantum efficiency of photodiode; This structure sensitization passage and flatness layer have effectively suppressed to reflect in the medium of incident light outside passage, thereby have shielded crosstalking of light; The reflection that this structural images transducer has avoided incident light to cause because of medium refraction index difference the dielectric material of CFA material substitution traditional structure.

The purpose of this utility model is achieved through the following technical solutions:

A kind of cmos image sensor structure, comprise high reflectivity film, double layer of metal line and colorful optical filter array, the high reflectivity film that is used for shielding incident light be arranged on the double layer of metal line around and the top, described colorful optical filter array is arranged in the sensitization passage of described cmos image sensor structure.

Can be found out that by the technical scheme that above-mentioned the utility model provides the utility model can effectively guide to incident light the surface of photodiode, thereby improve sensitivity and the quantum efficiency of photodiode; This structure sensitization passage and flatness layer have effectively suppressed to reflect in the medium of incident light outside passage, thereby have shielded crosstalking of light; The reflection that this structural images transducer has avoided incident light to cause because of medium refraction index difference the dielectric material of CFA material substitution traditional structure.This structural images transducer adopts metal connecting line and the dielectric layer of attenuate, has effectively shortened the distance on incident light arrival pixel surface.

Description of drawings

In order to be illustrated more clearly in the technical scheme of the utility model embodiment, the accompanying drawing of required use was done to introduce simply during the below will describe embodiment, apparently, accompanying drawing in the following describes only is embodiment more of the present utility model, for those of ordinary skill in the art, under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.

Fig. 1 is cmos image sensor photosensitive structure schematic diagram of the prior art;

The structural representation of the sensitization passage of the cmos image sensor that Fig. 2 provides for the utility model embodiment;

Optical path of incident light schematic diagram in the sensitization passage of the cmos image sensor that Fig. 3 provides for the utility model embodiment.

Embodiment

Below in conjunction with the accompanying drawing among the utility model embodiment, the technical scheme among the utility model embodiment is clearly and completely described, obviously, described embodiment only is the utility model part embodiment, rather than whole embodiment.Based on embodiment of the present utility model, those of ordinary skills belong to protection range of the present utility model not making the every other embodiment that obtains under the creative work prerequisite.

This embodiment provides a kind of sensitization passage of cmos image sensor, as shown in Figure 2, comprise high reflectivity film 207, double layer of metal line 204 and colorful optical filter array 208, the high reflectivity film 207 that is used for shielding incident light be arranged on double layer of metal line 204 around and the top, colorful optical filter array 208 is arranged in the sensitization passage of cmos image sensor structure.Wherein, the dielectric layer attenuate 1 μ m-2 μ m of the inner correspondence position of metal connecting line and cmos image sensor.

Concrete, the novel cmos image sensor structure that this embodiment proposes is to adopt double layer of metal line 204 on the basis of traditional cmos image sensor, and metal connecting line 204 and dielectric layer all carry out attenuate arrives photodiode 102 surfaces to shorten incident light distance.Around the metal connecting line 204 and deposited on top one deck high reflectivity film 207 with shielding incident light because of crosstalking that metal layer reflection causes.Photodiode 102 surface depositions have one deck high refractive index film 201 as anti-reflection layer, and high refractive index film wherein adopts Si ₃N ₄, the colorful optical filter array 208 that distributing above the anti-reflection layer places photodiode 102 surfaces with colorful optical filter array 208, has avoided incident light to reflect in different medium on the one hand, has also simplified technique simultaneously.

Further specify the structure of the cmos image sensor that this embodiment provides in conjunction with Fig. 3 incident light schematic diagram, the first incident light 301 and the second incident light 302 are incident lights of two bundle diverse locations, the first incident light 301 incides the surface of high reflectivity film 207 through colorful optical filter array 208 with certain angle of inclination, thereby high reflectivity film 207 has high reflection reflects the first incident light 301, and the light after the reflection arrives colorful optical filter array 208 and antireflective film Si ₃

N

₄201 interfaces, boundary material Si ₃N ₄Refractive index (being about 2.0) be higher than the refractive index (being about 1.5) of colorful optical filter array 208, so light arrives the surface of photodiode 102 after refraction occurs at this interface.Above the high reflectivity film 207 of metal level top, the film 207 of high reflectance reflects the second incident light 302 to the second incident light 302 with certain angular illumination, arrives metal surface and side thereby suppressed incident light.

P type backing material 100, shallow trench isolation 101, contact hole 202 and lenticule 209 in the cmos image sensor that this embodiment provides are identical with existing cmos image sensor among Fig. 1, state so no longer apply at this.

The technical scheme that adopts embodiment to provide, the utility model can effectively guide to incident light the surface of photodiode, thereby has improved sensitivity and the quantum efficiency of photodiode; This structure sensitization passage and flatness layer have effectively suppressed to reflect in the medium of incident light outside passage, thereby have shielded crosstalking of light; The reflection that this structural images transducer has avoided incident light to cause because of medium refraction index difference the dielectric material of CFA material substitution traditional structure.This structural images transducer adopts metal connecting line and the dielectric layer of attenuate, has effectively shortened the distance on incident light arrival pixel surface.

The above; it only is the better embodiment of the utility model; but protection range of the present utility model is not limited to this; anyly be familiar with those skilled in the art in the technical scope that the utility model discloses; the variation that can expect easily or replacement all should be encompassed within the protection range of the present utility model.

Claims

1. cmos image sensor structure, comprise high reflectivity film, double layer of metal line and colorful optical filter array, it is characterized in that, the high reflectivity film that is used for shielding incident light be arranged on the double layer of metal line around and the top, described colorful optical filter array is arranged in the sensitization passage of described cmos image sensor structure.

2. cmos image sensor structure according to claim 1 is characterized in that, the photodiode surface of described cmos image sensor is deposited with one deck high refractive index film.

3. cmos image sensor structure according to claim 2 is characterized in that, described high refractive index film adopts Si ₃N ₄

4. cmos image sensor structure according to claim 1 is characterized in that, the dielectric layer attenuate 1 μ m-2 μ m of the inner correspondence position of described metal connecting line and cmos image sensor.