CN1437263A - CMOS image sensor structure with low dark current and its configuration - Google Patents
CMOS image sensor structure with low dark current and its configuration Download PDFInfo
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- CN1437263A CN1437263A CN 02103421 CN02103421A CN1437263A CN 1437263 A CN1437263 A CN 1437263A CN 02103421 CN02103421 CN 02103421 CN 02103421 A CN02103421 A CN 02103421A CN 1437263 A CN1437263 A CN 1437263A
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- image sensor
- irradiation
- cmos image
- poly
- dark current
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Abstract
The present invention is CMOS image sensor structure with low dark current and its configuration. It has POLY with rest transistor grid to separate the illumination area of the photodiode and field effect oxide layer corner and to lower the leakage current produced by the interface between the illumination area and the field effect oxide layer corner. In addition, the two sides of the POLY is extended to the pixels of adjacent POLY for sharing to expand the illumination area and raise the filling factor.
Description
Technical field
The invention relates to a kind of CMOS image sensor structure and layout method thereof, and particularly relevant for a kind of CMOS image sensor structure and layout method thereof that reduces dark current.
Background technology
All the time, image is people's information representation mode of being easy to accept most always, also because so, people are devoted to observe image, preserve the research of image, consequently very abundant and polynary about the device and the equipment of image, just as the hand held colour camera, theftproof monitoring black-and-white photography machine, digital camera, facsimile machine and medical use transducer etc., these image processing equipment all can't do without wanting the application image sensing component, and because the high stability of CMOS image sensor, high sensitivity, low-work voltage, low consumption electric power, high impedance reaches plurality of advantages such as not being subjected to strong magnetic influence, is that it is widely used in wherein therefore.Yet, if with itself and Charged Coupled Device (Charge Coupled Device, be called for short CCD) compare, though then it has cheap and is easy to and combines with other control circuit, analog-to-digital circuit and digital signal processing circuit on the same chip, reach the purpose of so-called System On a Chip (SOC), but, also can't have the very long time for exposure because of its higher dark current can't be applied to the environment of low-light (level).
Summary of the invention
The objective of the invention is to propose a kind of CMOS image sensor structure that reduces dark current, reducing its dark current, and cooperate this image sensor architecture, propose a kind of layout method that it fills up coefficient that improves.
The invention provides a kind of CMOS image sensor structure that reduces dark current, it comprises irradiation diode, reset transistor, source flower transistor and output selection transistor.The irradiation diode is in order to receiving the irradiation of light source, and according to the current potential of the intensity reaction irradiation diode of light source.Show around the formed illumination area of irradiation diode that by the conclusion of many paper studies the interface of imitating oxide layer corner (Field Oxide Corner) with the field is to produce the topmost zone of leakage current, so the grid Poly of use reset transistor surrounds the illumination area of irradiation diode, itself and an effect oxide layer corner are separated, to reduce its dark current.Reset transistor is used for resetting irradiation diode current potential to the accurate position of resetting.Source flower transistor is used to provide the output current of irradiation diode current potential, to read irradiation diode current potential.Transistor is selected in output, is used for selecting whether to read the current potential of irradiation diode in this sensor pixel, accepts the intensity of light source irradiation to determine this sensor pixel.
The present invention provides a kind of CMOS image sensor layout method that reduces dark current in addition, and this imageing sensor comprises irradiation diode, reset transistor, source flower transistor and output selection transistor.The irradiation diode is in order to receiving the irradiation of light source, and according to the current potential of the intensity reaction irradiation diode of light source.Reset transistor is used for resetting irradiation diode current potential to the accurate position of resetting.Source flower transistor is used to provide the output current of irradiation diode current potential, to read irradiation diode current potential.Transistor is selected in output, is used for selecting whether to read the current potential of irradiation diode in this sensor pixel, accepts the intensity of light source irradiation to determine this sensor pixel.The Poly that wherein uses the reset transistor grid with the illumination area of irradiation diode with imitate an oxide layer corner and separate, and the both sides of this Poly are extended to be connected with the Poly of neighbor share, with the area of expansion illumination area, and improve it and fill up coefficient (Fill Factor).
As shown in the above description, interface with field effect oxide layer corner around the formed illumination area of irradiation diode is that the topmost zone of generation leakage current is the conclusion of many paper studies, therefore, the illumination area of irradiation diode is separated with an effect oxide layer corner, is for reducing the effective ways of CMOS image sensor dark current.
Description of drawings
Figure 1A and Figure 1B show a kind of structural representation and its profile of traditional CMOS image sensor;
Fig. 2 A and Fig. 2 B show structural representation and its profile of a kind of CMOS image sensor of preferred embodiment according to the present invention;
Fig. 3 shows the structure chart of a kind of CMOS image sensor 3 * 3 array layouts of preferred embodiment according to the present invention.
100: imageing sensor
105: illumination area
110: reset transistor
115: source flower transistor
120: transistor is selected in output
125: an effect oxide layer
130: the irradiation diode
135: reset transistor
140: source flower transistor
145: transistor is selected in output
200: imageing sensor
205: illumination area
210: reset transistor
215: source flower transistor
220: transistor is selected in output
225: an effect oxide layer
230: the irradiation diode
235: reset transistor
240: source flower transistor
245: transistor is selected in output
Embodiment
Please in the lump with reference to Figure 1A and Figure 1B, Figure 1A shows a kind of structural representation of traditional CMOS image sensor, Figure 1B then shows a kind of profile of traditional CMOS image sensor structure, by showing among the figure that this imageing sensor 100 comprises irradiation diode 130 and illumination area 105, reset transistor 110,135, source flower transistor 115,140 and output selection transistor 120,145.Please refer to Figure 1B, the mode of its operation is at first with reset transistor 135 conductings, extremely reset accurate with the current potential of replacement irradiation diode 130, this moment, irradiation diode 130 was because of receiving the irradiation of light source, and make that current potential begins to descend, when the time for exposure arrives, to export and select transistor 145 conductings, the current potential of irradiation diode 130 will export to via the driving of source flower transistor 140 and read circuit at this moment, via the current potential slippage of judging irradiation diode 130, can tell the intensity of penetrating light source.Yet, the current potential slippage of this irradiation diode 130 is influenced by the dark current of irradiation diode 130 also can, show around the irradiation diode 130 formed illumination areas that by the conclusion of many paper studies the interface of imitating oxide layer 125 corners with the field is to produce the topmost zone of leakage current, even, also easily produce noise because of the influence that is subjected to this dark current so traditional CMOS image sensor is not having under the situation of light source.
Shown in Fig. 2 A and Fig. 2 B, be structural representation and its profile according to a kind of CMOS image sensor of a preferred embodiment of the present invention, please in the lump with reference to figure 2A and Fig. 2 B, by showing among the figure that this imageing sensor 200 comprises irradiation diode 230 and illumination area 205 thereof equally, reset transistor 210,235, source flower transistor 215,240 and output select transistor 220,245, but the existing change of its structural arrangements, wherein the illumination area 205 of irradiation diode 230 is reset transistor 210,235 grid Poly surrounds with square, therefore isolate fully imitating oxide layer 225 corners with the field around the illumination area 205 of irradiation diode 230, this isolation is the effect that causes reducing dark current, thereby the quality of raising sensing image, and allow to prolong the time of exposure.
The structure of a kind of CMOS image sensor of a preferred embodiment of the present invention is made with 0.35 μ m technology, its pixel size is 7.5 μ m * 7.5 μ m, by showing among Fig. 2 A and Fig. 2 B, it surrounds the reset transistor 210 of irradiation diode 230 illumination areas 205,235 grid Poly both sides have extended to the border, both sides and have shared, because of reset transistor 210,235 grids are connected to reset control signal and use with the replacement of oxide-semiconductor control transistors, and when resetting, its action permutation of resetting is reset together, so all reset transistors 210 of same row, 235 grid Poly can connect shared, to enlarge its illumination area 205, and cause improving the effect that it fills up coefficient, please refer to Fig. 3, it is the structure chart of a kind of CMOS image sensor 3 * 3 array layouts of preferred embodiment of the present invention, figure calculates it and fills up coefficient and be approximately 41% thus, and the coefficient that fills up of conventional in layout only is about 35%, and the old friend, also can improve it and fill up coefficient except that reducing the dark current with this layout type.
Claims (7)
1, a kind of CMOS image sensor structure that reduces dark current is characterized in that, this structure comprises:
One irradiation diode, it receives the irradiation of a light source, and reacts an irradiation diode current potential according to the intensity of this light source, wherein uses a Poly that one illumination area of this irradiation diode and the field effect oxide layer corner of this imageing sensor are separated;
One reset transistor, its this irradiation diode current potential of resetting is to the accurate position of resetting;
One source pole is with lotus root device transistor, and it provides the output current of this irradiation diode current potential, to read this irradiation diode current potential; And
Transistor is selected in one output, and it selects whether to read this irradiation diode current potential.
2, the CMOS image sensor structure that reduces dark current as claimed in claim 1 is characterized in that, this Poly is the grid of this reset transistor.
3, the CMOS image sensor structure that reduces dark current as claimed in claim 2 is characterized in that, this Poly is with square this illumination area that surrounds.
4, the CMOS image sensor structure that reduces dark current as claimed in claim 3 is characterized in that, the both sides of this Poly extend to be connected with this Poly of neighbor shares.
5, the CMOS image sensor structure that reduces dark current as claimed in claim 4 is characterized in that, this image sensor pixel uses 0.35 μ m technology, and its size is 7.5 μ m * 7.5 μ m.
6, a kind of CMOS image sensor layout method that reduces dark current, this imageing sensor comprises at least: an irradiation diode, this irradiation diode receives the irradiation of a light source, and reacts an irradiation diode current potential according to the intensity of this light source; And a reset transistor, this reset transistor is reset this irradiation diode current potential to the accurate position of resetting, and it is characterized in that, and a Poly who uses this reset transistor grid separates the illumination area of this irradiation diode field effect oxide layer corner with this imageing sensor.
7, the CMOS image sensor layout method that reduces dark current as claimed in claim 6 is characterized in that, the both sides of this Poly extend to be connected with this Poly of neighbor shares.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02103421 CN1437263A (en) | 2002-02-05 | 2002-02-05 | CMOS image sensor structure with low dark current and its configuration |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02103421 CN1437263A (en) | 2002-02-05 | 2002-02-05 | CMOS image sensor structure with low dark current and its configuration |
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| Publication Number | Publication Date |
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| CN1437263A true CN1437263A (en) | 2003-08-20 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN 02103421 Withdrawn CN1437263A (en) | 2002-02-05 | 2002-02-05 | CMOS image sensor structure with low dark current and its configuration |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100423281C (en) * | 2004-12-30 | 2008-10-01 | 东部亚南半导体株式会社 | CMOS image sensor and method for manufacturing the same |
| US7700950B2 (en) | 2005-06-15 | 2010-04-20 | Jaroslav Hynecek | Image sensor with compact pixel layout |
| CN101171828B (en) * | 2005-05-04 | 2011-09-21 | 美光科技公司 | Method and apparatus for dark current and blooming suppression in 4T CMOS imager pixel |
-
2002
- 2002-02-05 CN CN 02103421 patent/CN1437263A/en not_active Withdrawn
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100423281C (en) * | 2004-12-30 | 2008-10-01 | 东部亚南半导体株式会社 | CMOS image sensor and method for manufacturing the same |
| CN101171828B (en) * | 2005-05-04 | 2011-09-21 | 美光科技公司 | Method and apparatus for dark current and blooming suppression in 4T CMOS imager pixel |
| US7700950B2 (en) | 2005-06-15 | 2010-04-20 | Jaroslav Hynecek | Image sensor with compact pixel layout |
| US8044446B2 (en) | 2005-06-15 | 2011-10-25 | Intellectual Ventures Ii Llc | Image sensor with compact pixel layout |
| US8217437B2 (en) | 2005-06-15 | 2012-07-10 | Intellectual Ventures Ii Llc | Image sensor with compact pixel layout |
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| C04 | Withdrawal of patent application after publication (patent law 2001) | ||
| WW01 | Invention patent application withdrawn after publication |