CN1731584A - Light-sensing area and peripheral circuit area insulated active image-finding element - Google Patents
Light-sensing area and peripheral circuit area insulated active image-finding element Download PDFInfo
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- CN1731584A CN1731584A CNA2004100551087A CN200410055108A CN1731584A CN 1731584 A CN1731584 A CN 1731584A CN A2004100551087 A CNA2004100551087 A CN A2004100551087A CN 200410055108 A CN200410055108 A CN 200410055108A CN 1731584 A CN1731584 A CN 1731584A
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- 230000002093 peripheral effect Effects 0.000 title claims abstract description 31
- 230000003287 optical effect Effects 0.000 claims description 51
- 238000009792 diffusion process Methods 0.000 claims description 26
- 239000000758 substrate Substances 0.000 claims description 17
- 238000002955 isolation Methods 0.000 claims description 11
- 239000004020 conductor Substances 0.000 claims description 7
- 230000004888 barrier function Effects 0.000 claims description 3
- 238000003860 storage Methods 0.000 claims description 3
- 238000010586 diagram Methods 0.000 description 10
- 239000004065 semiconductor Substances 0.000 description 5
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- 239000000463 material Substances 0.000 description 3
- 230000000295 complement effect Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 206010070834 Sensitisation Diseases 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
Disclosed is a driving viewfinder component for CMOS image sensor, which comprises a base, a photo sensing area, a peripheral circuit and insolated area. The photo sensing area and the peripheral circuit are formed on the base, the isolated area is formed between the photo sensing area and the peripheral circuit, and isolates them. The photo sensing area can generate light current according to received light beam. The peripheral circuit comprises a first transistor with source connected with a character line for selecting whether output the stored data in the photo sensing area; a second transistor with gate connected with the photo sensing area, source connected with drain of the first transistor, and drain connected with a voltage source; a third transistor with source connected with the photo sensing area and drain connected with the voltage power for resetting the photo sensing area.
Description
Technical field
The invention provides the active image-finding element of the CMOS image sensor that a kind of optical sensing area and peripheral circuit region isolate mutually, refer to a kind of active image-finding element of omitting electric current and improving fill factor, curve factor that reduces especially.
Background technology
CMOS (Complementary Metal Oxide Semiconductor) (complementary metal-oxide semiconductor, CMOS) image sensor (image sensing region) is general solid-state image sensing element, and existing carrier coupling device (charge-coupled device, trend CCD) of day by day replacing of CMOS image sensor.Because the CMOS image sensor is to make with traditional manufacture of semiconductor, therefore has the advantage that cost of manufacture is lower and component size is less, in addition, the CMOS image sensor also has high-quantum efficiency (quantum efficiency) and low noise advantages such as (read-out noise), therefore has been widely used on personal computer camera (PC camera) and the digital camera electronic products such as (digital camera).
Please refer to Fig. 1 and Fig. 2, Fig. 1 is the schematic diagram of the active image-finding element 10 of previous CMOS image sensor, and Fig. 2 is the initiatively circuit diagram of image-finding element 10 of Fig. 1.Initiatively image-finding element 10 includes a light sensitive diode D1, be used for the intensity of sensor light photograph, and three metal-oxide semiconductor (metal-oxide semiconductor, MOS) transistor M1-M3 is used as column select switch (row selector) M1, Current draw element (current source follower) M2 and replacement element (reset MOS) M3 respectively.Light sensitive diode D1 can produce photoelectric current according to light that its optical sensing area received, and column select switch M1 is used for selecting whether to export the photoelectric current that light sensitive diode D1 is produced.Current draw element M2 comes the output of modulation Current draw element M2 according to the electric charge (charge) of light sensitive diode D1.The light sensitive diode D1 and replacement element M3 is used for resetting, meaning is promptly when replacement element M3 conducting, make the voltage of light sensitive diode D1 be maintained at a fixed voltage value, its value is not subjected to optical sensing area to receive light and changes, and when replacement element M3 closed, the voltage of light sensitive diode D1 just received light along with optical sensing area and changes.
Initiatively the processing procedure of image-finding element 10 is conformance with standard CMOS processing procedures, its advantage is that cost is low and component size is less, but the diffusion region (diffusion) that its shortcoming is to reset between element M3 and the light sensitive diode D1 can produce the problem of omitting electric current, and the problem of fill factor, curve factor (fill factor) reduction.Generally speaking, the high more representative resolution of fill factor, curve factor is high more, and the equation of fill factor, curve factor is as follows:
Wherein ff represents fill factor, curve factor;
A represents the area of whole active image-finding element;
Av represents the area of optical sensing area.
And omit high slope place that electric current results from exhaustion region and the isolated area part of joining.Below will be in the prior art, the problem of omitting the problem of electric current and influence the fill factor, curve factor reduction explains.
Please refer to Fig. 3, Fig. 3 prolongs the profile (cross sectional diagram) of tangent line 3-3 ' direction for Fig. 1 active image-finding element 10, existing light sensitive diode D1 processing procedure comprises a P type substrate 12, the shallow doped region 16 of a N type, a N moldeed depth doped region 18, an and shallow trench isolation region (shallow trenchisolation, STI) 20, between the shallow doped region 16 of P type substrate 12 and N type an exhaustion region 14 is arranged.When exhaustion region 14 contacts with the smooth place of shallow trench isolation region 20, can't produce the omission electric current, therefore as shown in Figure 3, active image-finding element 10 prolongs tangent line 3-3 ' part and can't produce the omission electric current.
Please refer to Fig. 4, Fig. 4 prolongs the profile of tangent line 4-4 ' direction for Fig. 1 active image-finding element 10.Exhaustion region 14 1 ends contact with N moldeed depth doped region 18, and the other end contacts with the smooth place of shallow trench isolation region 20, because exhaustion region 14 does not contact with the high slope place of shallow trench isolation region 20 herein, therefore also can not produce the omission electric current herein.
Please refer to Fig. 5 and Fig. 6, Fig. 5 prolongs the profile of tangent line 5-5 ' direction for Fig. 1 active image-finding element 10, and Fig. 6 is the initiatively stereogram of image-finding element 10 of Fig. 5.As shown in Figure 6, because exhaustion region 14 1 ends can be crossed over the high slope place (select be denoted as 15 parts as institute's circle among Fig. 5) of shallow trench isolation region 20, so can form a PN and connect face (PN junction), PN connects face then can produce significant omission electric current.
Connect face for further specifying this PN, please consult Fig. 3 and Fig. 4 once more, when the tangent line 5-5 ' of present dynasty looks the top, promptly can see profile as Fig. 3, yet when look in the tangent line 5-5 ' of present dynasty below, promptly can see profile, therefore at the high slope place 15 of the shallow trench isolation region 20 on Fig. 5 left side as Fig. 4, promptly can produce this PN and connect face, and cause significant omission electric current.
Because image processing is to produce corresponding image gray scale according to the photoelectric current that light sensitive diode D1 produces, the image gray scale that therefore significant omission electric current can make image processing produce has tangible error.
Please refer to Fig. 7 and Fig. 8, Fig. 7 is for overcoming the schematic diagram of the active image-finding element 30 of omitting current problems, and Fig. 8 prolongs the profile of tangent line 8-8 ' direction for Fig. 7 active image-finding element 30.The two ends of exhaustion region 14 all contact with N moldeed depth doped region 18 among Fig. 8, and it can be avoided exhaustion region 14 to cross over the high slope place of shallow trench isolation region 20 and form PN and connect face, therefore can avoid producing significant omission electric current, but reduce fill factor, curve factor.Please refer to Fig. 7, because the two ends of exhaustion region 14 all contact with N moldeed depth doped region 18, therefore among Fig. 7 optical sensing area area (dotted portion) less than the optical sensing area area (dotted portion) of Fig. 1, meaning is the fill factor, curve factor of the fill factor, curve factor of Fig. 7 less than Fig. 1, and promptly initiatively the fill factor, curve factor of image-finding element 30 has reduced.Though initiatively image-finding element 30 can solve the problem of omitting electric current, has relatively reduced fill factor, curve factor.
As mentioned above, though the fill factor, curve factor of Fig. 1 active image-finding element 10 is bigger, because the diffusion region between replacement element M3 and the light sensitive diode D1 can produce the omission electric current, as Fig. 5.Though and Fig. 7 active image-finding element 30 can solve the problem of omitting electric current, has relatively reduced fill factor, curve factor.Therefore need a kind of method of omitting current problems and improving fill factor, curve factor that solves.
Summary of the invention
The invention provides the active image-finding element of the CMOS image sensor that a kind of optical sensing area and peripheral circuit region isolate mutually, to solve the above problems.
Active image-finding element of the present invention comprises a substrate, an optical sensing area, a peripheral circuit region and an isolated area (isolation region).This optical sensing area and this peripheral circuit region are formed in this substrate, and this isolated area is formed between this optical sensing area and this peripheral circuit region, and isolate this optical sensing area and this peripheral circuit region.This optical sensing area is used for producing photoelectric current according to the light that receives.This peripheral circuit region comprises a first transistor, its source electrode is connected in a character line, this the first transistor is used for selecting whether to export the data of this optical sensing area storage, a transistor seconds, and its grid is connected in this optical sensing area, source electrode is connected in the drain electrode of this first transistor, drain electrode is connected in a voltage source, and one the 3rd transistor, and its source electrode is connected in this optical sensing area, drain electrode is connected in this voltage source, the 3rd transistor this optical sensing area that is used for resetting.
Description of drawings
Fig. 1 is the schematic diagram of the active image-finding element of existing CMOS image sensor.
Fig. 2 is the initiatively circuit diagram of image-finding element of Fig. 1.
Fig. 3 prolongs the profile of tangent line 3-3 ' direction for Fig. 1 active image-finding element.
Fig. 4 prolongs the profile of tangent line 4-4 ' direction for Fig. 1 active image-finding element.
Fig. 5 prolongs the profile of tangent line 5-5 ' direction for Fig. 1 active image-finding element.
Fig. 6 prolongs the stereogram of tangent line 5-5 ' directional profile for Fig. 1 active image-finding element.
Fig. 7 is for overcoming the initiatively schematic diagram of the active image-finding element of the omission current problems of image-finding element of Fig. 1.
Fig. 8 prolongs the profile of tangent line 8-8 ' direction for Fig. 7 active image-finding element.
Fig. 9 is the schematic diagram of the present invention's active image-finding element.
Symbol description
10,30,40 initiatively image-finding element 12 substrates
14 exhaustion regions, 15 high slope places
16,18 doped regions, 20 shallow trench isolation region
42 plain conductors, 44 peripheral circuit regions
46 optical sensing areas, 48 isolated areas
D1 light sensitive diode M1, M2, M3 transistor
Embodiment
In order to solve problems of the prior art, the present invention is with the active image-finding element redesign of CMOS image sensor.Please refer to Fig. 9, Fig. 9 is the schematic diagram of the active image-finding element 40 of CMOS image sensor of the present invention, and its corresponding circuit diagram still is Fig. 2.Initiatively image-finding element 40 comprises a substrate 12, one optical sensing areas 46, a peripheral circuit region 44 and an isolated area 48.Optical sensing area 46, peripheral circuit region 44 and isolated area 48 are formed in the substrate 12, and isolated area 48 is formed between optical sensing area 46 and the peripheral circuit region 44, and isolate optical sensing area 46 and peripheral circuit region 44.
Because the present invention keeps apart optical sensing area 46 and peripheral circuit region 44, the grid of light sensitive diode D1 and transistor seconds M2 and utilize plain conductor 42 to link with the binding of the source electrode of the 3rd transistor M3, meaning is the grid of transistor seconds M2 is connected in second diffusion region, 18, the three transistor M3 of optical sensing area 46 via plain conductor 42 source electrode also is connected in optical sensing area 46 via plain conductor 42 second diffusion region 18.Compared to prior art, prior art utilization diffusion links (diffusionconnection) to have linked the 3rd transistor M3 and light sensitive diode D1, thereby can produce and Lou move electric current, and the present invention utilizes plain conductor 42 to link second diffusion region 18 of source electrode and the optical sensing area 46 of the 3rd transistor M3, and this can be avoided forming PN as Fig. 5 and connect face and produce the problem of Lou moving electric current.
Refer again to Fig. 1, Fig. 7 and Fig. 9, the new layout of active image-finding element 40 according to the present invention, the area of the optical sensing area of light sensitive diode D1 (dotted portion among Fig. 9) is big than the light sensing area (dotted portion) among Fig. 1 and Fig. 7, therefore can improve fill factor, curve factor, and then improves resolution.
In addition, the present invention initiatively substrate 12 of image-finding element 40 is the substrate of P type, and first diffusion region 16 of optical sensing area 46 and second diffusion region 18 are the N type.And three transistor M1-M3 in the peripheral circuit region 44 are NMOS, please in the lump with reference to figure 2 and Fig. 9, because the layout of Fig. 9, therefore the drain electrode of the first transistor M1 and the source electrode of transistor seconds M2 are same doped region, and the drain electrode of the drain electrode of transistor seconds M2 and the 3rd transistor M3 is same doped region.The isolated area 48 that is formed between optical sensing area 46 and the peripheral circuit region 44 is a shallow isolating trough insulating barrier (shallow trench isolation layer) or is a field oxide (field oxide layer), in order to isolate optical sensing area 46 and peripheral circuit region 44.What note is, except this isolated area 48 is arranged between optical sensing area 46 and the peripheral circuit region 44, isolated area is also arranged to isolate different elements around optical sensing area 46 and the peripheral circuit region 44, and its material also be the shallow isolating trough insulating barrier or is field oxide.In addition, though embodiments of the invention with the material of NMOS as M1-M3, yet the present invention is not restricted to this, can also PMOS carries out equalization as the material of M1-M3 and changes with revising and implement it.
Compared to prior art, the present invention keeps apart optical sensing area 46 and peripheral circuit region 44, Also be about to transistor M3 and light sensitive diode D1 and separate, it can solve because of transistor M3 and sensitization two The problem of the omission electric current that the diffusion region produces between the utmost point pipe D1, meaning no longer exists exhaustion region and isolated area High slope place contact to form the PN junction and produce and omit electric current (such as Fig. 5 and shown in Figure 6). This Outward, because the diffusion region is intactly at the range of exhaustion region, (shown in the optical sensing area 46 of Fig. 9), Fill factor, curve factor can improve significantly, thereby resolution is improved.
Claims (6)
1. optical sensing area and the peripheral circuit region active image-finding element of isolating mutually is characterized in that, comprises:
One substrate;
One optical sensing area is formed in this substrate, is used for producing photoelectric current according to the light that receives;
One peripheral circuit region is formed in this substrate, and this peripheral circuit region comprises:
One the first transistor, its source electrode is connected in a character line, and this first transistor is used for selecting whether to export the data of this optical sensing area storage;
One transistor seconds, its grid is connected in this optical sensing area, and source electrode is connected in the drain electrode of this first transistor, and drain electrode is connected in a voltage source; And
One the 3rd transistor, its source electrode is connected in this optical sensing area, and drain electrode is connected in this voltage source, the 3rd transistor this optical sensing area that is used for resetting; And
One isolated area (isolation region) is formed between this optical sensing area and this peripheral circuit region, and isolates this optical sensing area and this peripheral circuit region.
2. active image-finding element as claimed in claim 1 is characterized in that, this optical sensing area includes:
One first diffusion region is formed in this substrate;
One second diffusion region is formed on this first diffusion region, and the doping content of this second diffusion region is greater than the doping content of this first diffusion region; And
One exhaustion region is formed between this first diffusion region and this substrate, is used for receiving light to produce photoelectric current.
3. active image-finding element as claimed in claim 2, it is characterized in that, the grid of this transistor seconds is connected in second diffusion region of this optical sensor via a plain conductor, and the 3rd transistorized source electrode also is connected in second diffusion region of this optical sensing area via a plain conductor.
4. active image-finding element as claimed in claim 2 is characterized in that, this substrate is the P type, and this first and second diffusion region is the N type, and this three transistor is NMOS.
5. active image-finding element as claimed in claim 1 is characterized in that, the drain electrode of this first transistor and the source electrode of this transistor seconds are same doped region, and the drain electrode of this transistor seconds and the 3rd transistor drain are same doped region.
6. active image-finding element as claimed in claim 1 is characterized in that, this isolated area is that a shallow isolating trough insulating barrier and a field oxide are wherein arbitrary.
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| Application Number | Priority Date | Filing Date | Title |
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| CNB2004100551087A CN100369259C (en) | 2004-08-04 | 2004-08-04 | Light-sensing area and peripheral circuit area insulated active image-finding element |
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| CNB2004100551087A CN100369259C (en) | 2004-08-04 | 2004-08-04 | Light-sensing area and peripheral circuit area insulated active image-finding element |
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| CN100369259C CN100369259C (en) | 2008-02-13 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101714568B (en) * | 2006-07-10 | 2012-01-04 | 佳能株式会社 | Method for producing photoelectric conversion device |
| CN106940199A (en) * | 2017-03-03 | 2017-07-11 | 重庆湃芯微电子有限公司 | Optical frequency sensor with drain current suppressing |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US6160282A (en) * | 1998-04-21 | 2000-12-12 | Foveon, Inc. | CMOS image sensor employing silicide exclusion mask to reduce leakage and improve performance |
| US6534335B1 (en) * | 1999-07-22 | 2003-03-18 | Micron Technology, Inc. | Optimized low leakage diodes, including photodiodes |
| US20030085415A1 (en) * | 2001-11-02 | 2003-05-08 | Chong-Yao Chen | CMOS image sensor device |
| US20030106986A1 (en) * | 2001-12-07 | 2003-06-12 | Hsiu-Yu Cheng | Low dark current CMOS image sensor cell and array layout |
| US6888214B2 (en) * | 2002-11-12 | 2005-05-03 | Micron Technology, Inc. | Isolation techniques for reducing dark current in CMOS image sensors |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101714568B (en) * | 2006-07-10 | 2012-01-04 | 佳能株式会社 | Method for producing photoelectric conversion device |
| CN106940199A (en) * | 2017-03-03 | 2017-07-11 | 重庆湃芯微电子有限公司 | Optical frequency sensor with drain current suppressing |
| CN106940199B (en) * | 2017-03-03 | 2020-04-24 | 重庆湃芯创智微电子有限公司 | Optical frequency sensor with leakage current suppression |
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