CN112117292A - Method for reducing dark current on surface of image sensor and image sensor - Google Patents
Method for reducing dark current on surface of image sensor and image sensor Download PDFInfo
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- CN112117292A CN112117292A CN202011207998.4A CN202011207998A CN112117292A CN 112117292 A CN112117292 A CN 112117292A CN 202011207998 A CN202011207998 A CN 202011207998A CN 112117292 A CN112117292 A CN 112117292A
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- 238000000034 method Methods 0.000 title claims abstract description 23
- 239000000463 material Substances 0.000 claims abstract description 39
- 229910044991 metal oxide Inorganic materials 0.000 claims abstract description 34
- 150000004706 metal oxides Chemical class 0.000 claims abstract description 34
- 238000000137 annealing Methods 0.000 claims abstract description 11
- 229910052681 coesite Inorganic materials 0.000 claims description 4
- 229910052906 cristobalite Inorganic materials 0.000 claims description 4
- 239000001257 hydrogen Substances 0.000 claims description 4
- 229910052739 hydrogen Inorganic materials 0.000 claims description 4
- 239000000377 silicon dioxide Substances 0.000 claims description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 4
- 229910052682 stishovite Inorganic materials 0.000 claims description 4
- 229910052905 tridymite Inorganic materials 0.000 claims description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 2
- XOLBLPGZBRYERU-UHFFFAOYSA-N SnO2 Inorganic materials O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 claims description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 2
- 229910052593 corundum Inorganic materials 0.000 claims description 2
- 230000000694 effects Effects 0.000 claims description 2
- CJNBYAVZURUTKZ-UHFFFAOYSA-N hafnium(IV) oxide Inorganic materials O=[Hf]=O CJNBYAVZURUTKZ-UHFFFAOYSA-N 0.000 claims description 2
- 229910001845 yogo sapphire Inorganic materials 0.000 claims description 2
- 239000003989 dielectric material Substances 0.000 claims 1
- 238000003384 imaging method Methods 0.000 abstract description 8
- 238000010586 diagram Methods 0.000 description 7
- 238000009792 diffusion process Methods 0.000 description 5
- 125000004430 oxygen atom Chemical group O* 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000005034 decoration Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 229910000530 Gallium indium arsenide Inorganic materials 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- WPYVAWXEWQSOGY-UHFFFAOYSA-N indium antimonide Chemical compound [Sb]#[In] WPYVAWXEWQSOGY-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000002161 passivation Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14683—Processes or apparatus peculiar to the manufacture or treatment of these devices or parts thereof
- H01L27/14694—The active layers comprising only AIIIBV compounds, e.g. GaAs, InP
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14601—Structural or functional details thereof
- H01L27/1462—Coatings
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14643—Photodiode arrays; MOS imagers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14683—Processes or apparatus peculiar to the manufacture or treatment of these devices or parts thereof
- H01L27/14698—Post-treatment for the devices, e.g. annealing, impurity-gettering, shor-circuit elimination, recrystallisation
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- Transforming Light Signals Into Electric Signals (AREA)
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Abstract
The invention provides a method for reducing dark current on the surface of an image sensor and the image sensor. The method comprises the following steps: growing an interface repairing layer on the surface of the image sensor, wherein the interface repairing layer is made of an oxide material; growing a charge trapping layer on the surface of the interface repairing layer, wherein the charge trapping layer is made of a high dielectric constant material and is used for trapping charges on the surface of the sensor; growing a metal oxide layer on the surface of the charge trapping layer, wherein the material characteristic of the metal oxide layer is that the Gibbs free energy is higher than that of the element oxide on the surface of the sensor; and (6) annealing. The technical scheme can reduce the surface dark current of the image sensor, reduce the noise of the image sensor and obviously improve the imaging quality.
Description
Technical Field
The present invention relates to the field of semiconductors, and in particular, to a method for reducing dark current on a surface of an image sensor and an image sensor.
Background
For group III-V (InGaAs, InP, InSb, etc.) image sensors, the imaging quality of the image sensor is an important issue. The surface of the III-V family material exposed after the back surface process is thinned has defects, dangling bonds and damages, which can generate surface dark current and influence the imaging quality of the image sensor. The surface dark current causes the noise of the image sensor to increase sharply, the imaging quality is greatly reduced, and even effective imaging is difficult. Therefore, reducing surface dark current becomes a key to group III-V image sensor applications.
Disclosure of Invention
The invention aims to solve the technical problem that the repair capability is limited in the traditional III-V material surface passivation method, and provides a method for reducing the dark current on the surface of an image sensor and the image sensor.
In order to solve the above problem, the present invention provides a method for reducing dark current on the surface of an image sensor, comprising the following steps: growing an interface repairing layer on the surface of the image sensor, wherein the interface repairing layer is made of an oxide material; growing a charge trapping layer on the surface of the interface repairing layer, wherein the charge trapping layer is made of a high dielectric constant material and is used for trapping charges on the surface of the sensor; growing a metal oxide layer on the surface of the charge trapping layer, wherein the material characteristic of the metal oxide layer is that the Gibbs free energy is higher than that of the element oxide on the surface of the sensor; and (6) annealing.
The invention also provides an image sensor, wherein the surface of the image sensor has a laminated structure, and the laminated structure sequentially comprises: the image sensor comprises an interface repairing layer, a charge trapping layer and a metal oxide layer, wherein the Gibbs free energy of the material of the metal oxide layer is higher than that of the surface element oxide of the image sensor.
The technical scheme can reduce the surface dark current of the image sensor, reduce the noise of the image sensor and obviously improve the imaging quality.
Drawings
FIG. 1 is a schematic diagram illustrating the steps of one embodiment of the present invention.
FIGS. 2A-2D are schematic views of the process of steps S10-S13 shown in FIG. 1.
FIG. 3 is a diagram illustrating a dark current source on an image sensor according to an embodiment of the present invention.
FIG. 4 is a schematic diagram illustrating the diffusion of oxygen atoms from a metal oxide within a device according to an embodiment of the present invention.
Fig. 5 is a schematic structural diagram of an image sensor according to an embodiment of the invention.
Detailed Description
The following describes a method for reducing dark current on a surface of an image sensor and an embodiment of the image sensor in detail with reference to the accompanying drawings.
FIG. 1 is a schematic diagram illustrating the steps of an embodiment of the present invention, including: step S10, providing an image sensor; step S11, growing an interface repairing layer on the surface of the image sensor, wherein the interface repairing layer is made of oxide materials; step S12, growing a charge trapping layer on the surface of the interface repairing layer, wherein the charge trapping layer is made of a high dielectric constant material and is used for trapping charges on the surface of the sensor; step S13, growing a metal oxide layer on the surface of the charge trapping layer, wherein the material characteristic of the metal oxide layer is that Gibbs free energy is higher than that of the element oxide on the surface of the sensor; step S14, annealing: step S15, removing the metal oxide layer.
Referring to step S10, shown in fig. 2A, an image sensor 20 is provided. The structure of the surface of the image sensor 20 includes a Si substrate 200 and a photodiode 201. In one embodiment, the image sensor 20 is a III-V image sensor, and the photodiode 201 is a III-V photodiode.
FIG. 3 is a diagram illustrating a dark current source on an image sensor according to an embodiment of the present invention. The light incident surface of the image sensor 20 is thinned, and defects, dangling bonds and damages shown in a dotted line frame are generated, and the damages can generate surface dark current and reduce the imaging quality of the image sensor. The following steps described in this embodiment are intended to repair this damage.
Referring to step S11, as shown in fig. 2B, an interface repair layer 202 is grown on the surface of the image sensor 20, and the interface repair layer is made of an oxide material. In this embodiment, the interface repair layer 202 is made of SiO2The material has a thickness of 1nm-5 nm. The growth temperature used is below 300 ℃.
Referring to step S12, as shown in fig. 2C, a charge trapping layer 203 is grown on the surface of the interfacial repair layer 202, and the charge trapping layer 203 is made of a high dielectric constant material. In one embodiment, the charge trapping layer 203 has a thickness of 5nm to 50 nm. The adopted high dielectric constant material is HfO2Or Al2O3The material is used for trapping interface charges and reducing dark current on the surface of the device.
Referring to step S13, as shown in fig. 2D, a metal oxide layer 204 is grown on the surface of the charge trapping layer 203, and the grown metal oxide layer 204 has a material property that the gibbs free energy is higher than that of the elemental oxide on the surface of the sensor. In one embodiment, the image sensor 20 is a group III-V image sensor, i.e., the material of the surface elements of the image sensor is a group III-V semiconductor material, then in this embodiment, it should be assumed that the material property of the grown metal oxide layer 204 is a higher gibbs free energy than the gibbs free energy of the oxide formed by the group III-V material on the surface of the image sensor 20. The metal oxide layer 204 is made of a material selected from PdO, NiO, CoO, and SnO2One or more combinations of; the grown metal oxide layer 204 is 5nm to 50nm thick.
And step S14, annealing. The annealing is performed in a mixed atmosphere of nitrogen and hydrogen, or in a hydrogen atmosphere. In the case of using the above-described material as the metal oxide layer 204, oxygen diffusion occurs by utilizing the gibbs free energy difference during annealing to improve the interface.
FIG. 4 is a schematic diagram illustrating the diffusion of oxygen atoms of the metal oxide in the device during the annealing process of step S14. The process is shown in which the material comprising the metal oxide layer 204 utilizes the gibbs free energy difference to produce oxygen diffusion during annealing to further repair the interface, thereby reducing the surface dark current.
From the above-described annealing principle, it can be seen that a thickness of the grown metal oxide layer of 5nm to 50nm is a preferred thickness range. If the thickness is too thin, oxygen atoms cannot be sufficiently diffused, and an ideal effect is difficult to achieve; if the thickness is too thick, the oxygen diffusion is saturated, and the excess thickness makes the excess oxygen atoms cross the high-k material to form a rough interface with the III-V group, which is mixed with InO, GaO and AsO, and is not favorable for improving the interface.
And removing the metal oxide layer to reduce the influence of the metal oxide on incident light. Referring to step S15, the metal oxide layer 204 is removed. This step is an optional step, and the amount of light entering the image sensor 20 can be increased. Especially for the metal oxide layer 204 made of opaque material, this step needs to be performed to ensure that the image sensor 20 can image.
Next, a specific embodiment of an image sensor obtained after the above steps are performed is given with reference to the accompanying drawings, wherein the structure of the image sensor is as shown in fig. 5, and the image sensor includes an image sensor 50, and a surface laminated structure, the laminated structure sequentially includes an interface repair layer 51, a charge trapping layer 52, and a metal oxide layer 53, and the gibbs free energy of the material of the metal oxide layer 53 is higher than the gibbs free energy of the surface element oxide of the image sensor 50. According to the principle disclosed in the implementation steps of the specific implementation mode of the method, the structure can effectively reduce the surface dark current of the image sensor, reduce the noise of the image sensor and obviously improve the imaging quality.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (13)
1. A method for reducing dark current on a surface of an image sensor, comprising the steps of:
growing an interface repairing layer on the surface of the image sensor, wherein the interface repairing layer is made of an oxide material; growing a charge trapping layer on the surface of the interface repairing layer, wherein the charge trapping layer is made of a high dielectric constant material and is used for trapping charges on the surface of the sensor;
growing a metal oxide layer on the surface of the charge trapping layer, wherein the material characteristic of the metal oxide layer is that the Gibbs free energy is higher than that of the element oxide on the surface of the sensor;
and (6) annealing.
2. The method of claim 1, wherein the image sensor is a group III-V image sensor.
3. The method of claim 1, wherein the interfacial repair layer is SiO2The thickness of the material is 1nm-5 nm.
4. The method of claim 1, wherein the charge trapping layer is formed of a high dielectric constant material, i.e., a material having a dielectric constant higher than that of SiO2The thickness of the material is 5nm-50 nm.
5. The method of claim 1, wherein the high-k dielectric material is HfO2Or Al2O3A material.
6. The method of claim 1, wherein the metal oxide layer is formed of a material selected from the group consisting of PdO, NiO, CoO, and SnO2One or more of the above.
7. The method of claim 6, wherein the metal oxide layer has a thickness of 5nm to 50 nm.
8. The method of claim 1, further comprising the step of removing the metal oxide layer to reduce the effect of the metal oxide on the incident light.
9. The method of claim 1, wherein the annealing is performed in a mixed nitrogen-hydrogen atmosphere or a hydrogen atmosphere.
10. An image sensor, characterized in that the image sensor surface has a laminated structure, which in turn is: the image sensor comprises an interface repairing layer, a charge trapping layer and a metal oxide layer, wherein the material characteristic of the metal oxide layer is that Gibbs free energy is higher than that of element oxide on the surface of the image sensor.
11. The image sensor of claim 10, wherein the interfacial repair layer is SiO2The thickness of the interface repairing layer is 1nm-5 nm.
12. The image sensor as in claim 10, wherein the charge trapping layer is made of a high dielectric constant material, and the thickness of the charge trapping layer is 5nm to 50 nm.
13. The image sensor as in claim 10, wherein the metal oxide layer has a thickness of 5nm to 50 nm.
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| CN202011207998.4A CN112117292A (en) | 2020-11-03 | 2020-11-03 | Method for reducing dark current on surface of image sensor and image sensor |
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| CN202011207998.4A CN112117292A (en) | 2020-11-03 | 2020-11-03 | Method for reducing dark current on surface of image sensor and image sensor |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101515567A (en) * | 2008-02-19 | 2009-08-26 | 索尼株式会社 | Method for manufacturing solid-state imaging device |
| CN107768393A (en) * | 2017-10-20 | 2018-03-06 | 德淮半导体有限公司 | Semiconductor devices and preparation method thereof |
| US20200292391A1 (en) * | 2019-03-14 | 2020-09-17 | Fujitsu Limited | Infrared detector, imaging device including the same, and manufacturing method for infrared detector |
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- 2020-11-03 CN CN202011207998.4A patent/CN112117292A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101515567A (en) * | 2008-02-19 | 2009-08-26 | 索尼株式会社 | Method for manufacturing solid-state imaging device |
| CN107768393A (en) * | 2017-10-20 | 2018-03-06 | 德淮半导体有限公司 | Semiconductor devices and preparation method thereof |
| US20200292391A1 (en) * | 2019-03-14 | 2020-09-17 | Fujitsu Limited | Infrared detector, imaging device including the same, and manufacturing method for infrared detector |
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