CN111987117A - Output node structure of CCD image sensor and manufacturing process thereof - Google Patents
Output node structure of CCD image sensor and manufacturing process thereof Download PDFInfo
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- CN111987117A CN111987117A CN202010900406.0A CN202010900406A CN111987117A CN 111987117 A CN111987117 A CN 111987117A CN 202010900406 A CN202010900406 A CN 202010900406A CN 111987117 A CN111987117 A CN 111987117A
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- output node
- injection region
- contact hole
- substrate
- image sensor
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- 238000004519 manufacturing process Methods 0.000 title claims description 10
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims abstract description 67
- 238000002347 injection Methods 0.000 claims abstract description 50
- 239000007924 injection Substances 0.000 claims abstract description 50
- 229920005591 polysilicon Polymers 0.000 claims abstract description 44
- 239000000758 substrate Substances 0.000 claims abstract description 38
- 230000003647 oxidation Effects 0.000 claims abstract description 4
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 4
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 6
- 229910052698 phosphorus Inorganic materials 0.000 claims description 6
- 239000011574 phosphorus Substances 0.000 claims description 6
- 238000005530 etching Methods 0.000 claims description 5
- 238000000034 method Methods 0.000 claims description 5
- 238000002513 implantation Methods 0.000 claims description 4
- 238000000151 deposition Methods 0.000 claims description 3
- 239000012535 impurity Substances 0.000 claims description 3
- 230000001590 oxidative effect Effects 0.000 claims description 2
- 239000003990 capacitor Substances 0.000 abstract description 13
- 229910052751 metal Inorganic materials 0.000 abstract description 7
- 239000002184 metal Substances 0.000 abstract description 7
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical group [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 abstract description 2
- 239000000203 mixture Substances 0.000 abstract description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 6
- 229910052782 aluminium Inorganic materials 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 238000010586 diagram Methods 0.000 description 2
- 229910052814 silicon oxide Inorganic materials 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
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- H01L27/14812—
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- Solid State Image Pick-Up Elements (AREA)
Abstract
The invention discloses an output node structure of a CCD (charge coupled device) image sensor, which comprises a substrate, wherein a grid dielectric layer is arranged on the substrate, an output node injection region is arranged at the upper part of the substrate, a contact hole is formed in the grid dielectric layer, a polycrystalline silicon electrode is also arranged on the grid dielectric layer, the lower end of the polycrystalline silicon electrode extends into the contact hole and is electrically connected with the output node injection region, and an oxidation layer covers the upper end of the polycrystalline silicon electrode. In the invention, the output node injection region is directly connected with the polysilicon electrode, so that a metal aluminum structure is eliminated, and the composition of an output node capacitor is reduced; the size of the contact hole can be reduced, so that the areas of the output node injection region, the polycrystalline silicon electrode and the substrate can be correspondingly reduced, the capacitance of the output node injection region to the substrate and the capacitance of the polycrystalline silicon electrode to the substrate are reduced, the capacitance of the output node is further reduced, and the charge conversion factor of the CCD image sensor is improved.
Description
Technical Field
The invention relates to the field of CCD image sensors, in particular to an output node structure of a CCD image sensor and a manufacturing process thereof.
Background
The charge conversion factor of a CCD image sensor represents the device's ability to convert signal charge to an output voltage, i.e., how much output voltage can be generated per electron, in units of μ V/e-. The higher the charge conversion factor is, the larger the output voltage obtained by the same number of electrons is, the more the processing of a back-end circuit is facilitated, and meanwhile, the detection capability of the device can be improved. The magnitude of the charge conversion factor is mainly determined by the capacitance value of the CCD output node, and the larger the capacitance is, the smaller the charge conversion factor is. Therefore, to increase the charge conversion factor of the CCD, it is necessary to reduce the output node capacitance. The capacitance of the output node is mainly determined by the area of the output node, i.e., the area of the output node needs to be reduced. As shown in fig. 1, in the conventional CCD output node structure, contact holes 6 are respectively etched above an output node injection region 3 and a polysilicon electrode 4, and then metal aluminum 7 is respectively connected to the output node injection region 3 and the polysilicon electrode 4 through the two contact holes 6, so that the capacitance of the output node is composed of three parts, namely, a capacitor C1 of the output node injection region 3 to a substrate 1, a capacitor C2 of the polysilicon electrode 4 to the substrate 1, and a capacitor C3 of the metal aluminum 7 to the substrate 1, and is affected by the structural areas of the four parts, namely, the substrate 1, the output node injection region 3, the polysilicon electrode 4, and the metal aluminum 7.
Disclosure of Invention
The invention aims to provide an output node structure of a CCD image sensor with a high charge conversion factor and a manufacturing process thereof.
The technical scheme of the invention is as follows:
an output node structure of a CCD image sensor comprises a substrate, wherein a gate dielectric layer is arranged on the substrate, an output node injection region is arranged at the upper part of the substrate, a contact hole is formed in the gate dielectric layer, and the contact hole is positioned above the output node injection region; and a polycrystalline silicon electrode is arranged on the grid dielectric layer at a position corresponding to the upper part of the output node injection region, the lower end of the polycrystalline silicon electrode extends into the contact hole and is electrically connected with the output node injection region, and an oxidation layer covers the upper end of the polycrystalline silicon electrode.
Furthermore, the polysilicon electrode is doped with n-type phosphorus with the doping concentration of 1022/cm3Magnitude.
Further, the size of the contact hole is 1 μm × 1 μm.
Further, the thickness of the polycrystalline silicon electrode is 700nm-800 nm.
Furthermore, the contact hole and the polysilicon electrode are both arranged right above the output node injection region.
A manufacturing process of an output node of a CCD image sensor comprises the following steps:
growing a gate dielectric layer on the substrate;
injecting n-type impurities into the upper part of the substrate to form an output node injection region;
etching part of the gate dielectric layer above the output node injection region, exposing the output node injection region and forming a contact hole;
depositing a layer of polycrystalline silicon on the gate dielectric layer, wherein the polycrystalline silicon extends into the contact hole and is electrically connected with the output node injection region;
etching the polysilicon to form a polysilicon electrode;
and oxidizing the polysilicon electrode to form an oxide layer above the polysilicon electrode.
Furthermore, the polysilicon electrode is doped with n-type phosphorus with the doping concentration of 1022/cm3Magnitude.
Further, the size of the contact hole is 1 μm × 1 μm.
Further, the thickness of the polycrystalline silicon electrode is 700nm-800 nm.
Furthermore, the contact hole and the polysilicon electrode are both arranged right above the output node injection region.
Has the advantages that: according to the invention, by improving the doping concentration of the polysilicon electrode and directly connecting the output node injection region with the polysilicon electrode, a metal aluminum structure is cancelled, and the composition of the output node capacitor is reduced, so that the output node capacitor is reduced; in addition, the output node injection region is in direct contact with the polycrystalline silicon electrode, and the size of the contact hole can be reduced, so that the areas of the output node injection region, the polycrystalline silicon electrode and the substrate can be correspondingly reduced, the capacitance of the output node injection region to the substrate and the capacitance of the polycrystalline silicon electrode to the substrate are further reduced, the capacitance of the output node is further reduced, and the charge conversion factor of the CCD image sensor is improved.
Drawings
Fig. 1 is a schematic diagram of an output node structure of a CCD image sensor in the prior art;
FIG. 2 is a schematic diagram of an output node structure of a CCD image sensor according to the present invention;
fig. 3 is a flow chart of a process for manufacturing an output node of the CCD image sensor according to the present invention.
In the figure: 1. the structure comprises a substrate, 2 a gate dielectric layer, 3 an output node injection region, 4 a polycrystalline silicon electrode, 5 an oxidation layer, 6 a contact hole and 7 metal aluminum.
Detailed Description
In order to make the technical solutions in the embodiments of the present invention better understood and make the above objects, features and advantages of the embodiments of the present invention more comprehensible, the technical solutions in the embodiments of the present invention are described in further detail below with reference to the accompanying drawings.
In the description of the present invention, unless otherwise specified and limited, it is to be noted that the term "connected" is to be interpreted broadly, and may be, for example, a mechanical connection or an electrical connection, or a communication between two elements, or may be a direct connection or an indirect connection through an intermediate medium, and a specific meaning of the term may be understood by those skilled in the art according to specific situations.
As shown in fig. 2, a preferred embodiment of the output node structure of the CCD image sensor of the present invention includes a substrate 1, where the substrate 1 is a silicon substrate, a gate dielectric layer 2 is disposed on the substrate 1, an output node injection region 3 is further formed on the upper portion of the substrate 1 by an injection manner, a contact hole 6 is disposed on the gate dielectric layer 2, and the contact hole 6 is located right above the output node injection region 3; the size of the contact hole 6 can reach 1 μm × 1 μm at the minimum.
A polysilicon electrode 4 is arranged on the gate dielectric layer 2 at a position corresponding to the position right above the output node injection region 3, and the thickness of the polysilicon electrode is 700nm-800nm, preferably 750 nm; the polysilicon electrode 4 is doped with n-type phosphorus with a doping concentration of 1022/cm3Of the order of 3X 1022/cm3～5×1022/cm3. The lower end of the polysilicon electrode 4 extends into the contact hole 6 and is electrically connected with the output node injection region 3, and the output node injection region 3 and the surface of the polysilicon electrode 4The area of the contact hole is larger than the area of the hole opening of the contact hole 6, the upper end of the polysilicon electrode 4 is covered with an oxide layer 5, and the oxide layer 5 is silicon oxide.
In this embodiment, the doping concentration of the polysilicon electrode 4 is set to 1021/cm3Increased by an order of magnitude of 1022/cm3The output node injection region 3 is directly connected with the polysilicon electrode 4, the metal aluminum 7 is omitted, and the capacitor of the output node structure only consists of a capacitor C1 and a capacitor C2, wherein the capacitor C1 is the capacitor of the output node injection region 3 to the substrate 1, and the capacitor C2 is the capacitor of the polysilicon electrode 4 to the substrate 1; the capacitance C3 of the aluminum metal 7 to the substrate 1 is removed relative to the prior art, so that the capacitance of the output node is reduced. In addition, the modified structure can reduce the size of the contact hole 6 to 1 μm × 1 μm because the output node injection region 3 is in direct contact with the polysilicon electrode 4 (in the output node of the prior art, the size of the contact hole 6 is generally not less than 2 μm × 2 μm), so that the areas of the output node injection region 3, the polysilicon electrode 4 and the substrate 1 can be correspondingly reduced. Under the same condition, the areas of the output node injection region 3 and the polysilicon electrode 4 in the output node of the prior art are both 3 Mum multiplied by 3 Mum; in this embodiment, the area of the output node implantation region 3 and the area of the polysilicon electrode 4 only need to be 2 μm × 2 μm, and the area of the substrate 1 can be correspondingly reduced, so as to reduce the capacitance C1 of the output node implantation region 3 to the substrate 1 and the capacitance C2 of the polysilicon electrode 4 to the substrate 1, further reduce the capacitance of the output node, and improve the charge conversion factor of the CCD image sensor.
As shown in fig. 3, a preferred embodiment of the manufacturing process of the output node of the CCD image sensor of the present invention comprises the following steps:
a gate dielectric layer 2 is grown over the entire substrate 1, the gate dielectric layer 2 typically being comprised of silicon dioxide and silicon nitride.
An n-type impurity is implanted into the upper portion of the substrate 1 to form an output node implantation region 3.
And etching part of the gate dielectric layer 2 right above the output node injection region 3, exposing the output node injection region 3, wherein the etched area is smaller than that of the output node injection region 3, forming a contact hole 6, and the minimum size of the contact hole 6 can reach 1 micrometer multiplied by 1 micrometer.
Depositing a layer of polycrystalline silicon on the gate dielectric layer 2, wherein the polycrystalline silicon extends into the contact hole 6 and is electrically connected with the output node injection region 3; the polysilicon is doped with n-type phosphorus with a doping concentration of 1022/cm3Of the order of 3X 1022/cm3～5×1022/cm3(ii) a The thickness of the polysilicon at the contact hole 6 is 700nm to 800nm, preferably 750 nm.
The polysilicon not located in the region directly above the output node injection region 3 is etched away to form a polysilicon electrode 4 having an area substantially equal to that of the output node injection region 3.
The polysilicon electrode 4 is oxidized to form an oxide layer 5 composed of silicon oxide above it, thereby fabricating an output node forming a CCD image sensor.
The undescribed parts of the present invention are consistent with the prior art, and are not described herein.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent structures made by using the contents of the present specification and the drawings can be directly or indirectly applied to other related technical fields, and are within the scope of the present invention.
Claims (10)
1. An output node structure of a CCD image sensor is characterized by comprising a substrate, wherein a gate dielectric layer is arranged on the substrate, an output node injection region is arranged at the upper part of the substrate, a contact hole is formed in the gate dielectric layer, and the contact hole is positioned above the output node injection region; and a polycrystalline silicon electrode is arranged on the grid dielectric layer at a position corresponding to the upper part of the output node injection region, the lower end of the polycrystalline silicon electrode extends into the contact hole and is electrically connected with the output node injection region, and an oxidation layer covers the upper end of the polycrystalline silicon electrode.
2. The CCD image sensor output node structure and its manufacturing process of claim 1, wherein said polysilicon electrode is doped with n-type phosphorus with a doping concentration of 1022/cm3Magnitude.
3. The output node structure of the CCD image sensor as claimed in claim 1, wherein the size of the contact hole is 1 μm x 1 μm.
4. The output node structure of the CCD image sensor as claimed in claim 1, wherein the thickness of the polysilicon electrode is 700nm to 800 nm.
5. The output node structure of the CCD image sensor as claimed in any one of claims 1 to 4, wherein the contact hole and the polysilicon electrode are disposed right above the output node implantation region.
6. The manufacturing process of the output node of the CCD image sensor is characterized by comprising the following steps of:
growing a gate dielectric layer on the substrate;
injecting n-type impurities into the upper part of the substrate to form an output node injection region;
etching part of the gate dielectric layer above the output node injection region, exposing the output node injection region and forming a contact hole;
depositing a layer of polycrystalline silicon on the gate dielectric layer, wherein the polycrystalline silicon extends into the contact hole and is electrically connected with the output node injection region;
etching the polysilicon to form a polysilicon electrode;
and oxidizing the polysilicon electrode to form an oxide layer above the polysilicon electrode.
7. The process of claim 6, wherein the polysilicon electrode is doped with n-type phosphorus with a doping concentration of 1022/cm3Magnitude.
8. The process of claim 6, wherein the contact hole has a size of 1 μm x 1 μm.
9. The process for fabricating an output node of a CCD image sensor according to claim 6, wherein the thickness of the polysilicon electrode is 700nm to 800 nm.
10. The process for manufacturing an output node of a CCD image sensor as claimed in any one of claims 6 to 9, wherein the contact hole and the polysilicon electrode are both disposed right above the injection region of the output node.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010900406.0A CN111987117A (en) | 2020-09-01 | 2020-09-01 | Output node structure of CCD image sensor and manufacturing process thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010900406.0A CN111987117A (en) | 2020-09-01 | 2020-09-01 | Output node structure of CCD image sensor and manufacturing process thereof |
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| CN111987117A true CN111987117A (en) | 2020-11-24 |
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| CN202010900406.0A Pending CN111987117A (en) | 2020-09-01 | 2020-09-01 | Output node structure of CCD image sensor and manufacturing process thereof |
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Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03116840A (en) * | 1989-09-29 | 1991-05-17 | Sony Corp | Charge transfer device |
| JPH04280680A (en) * | 1991-03-08 | 1992-10-06 | Sony Corp | S0lid-state image pickup device |
| US5432363A (en) * | 1992-01-30 | 1995-07-11 | Matsushita Electric Industrial Co., Ltd. | Solid-state image pickup device and manufacturing method of the same |
| US5591997A (en) * | 1995-01-17 | 1997-01-07 | Eastman Kodak Company | Low capacitance floating diffusion structure for a solid state image sensor |
| US5904494A (en) * | 1996-04-09 | 1999-05-18 | Nec Corporation | Fabrication process for solid-state image pick-up device with CCD register |
| JP2002270810A (en) * | 2001-03-08 | 2002-09-20 | Sharp Corp | Solid-state image sensor |
| US20040031976A1 (en) * | 2002-08-19 | 2004-02-19 | Fuji Photo Film Co.,Ltd. | Semiconductor device and its manufacture |
| US20080283726A1 (en) * | 2006-09-20 | 2008-11-20 | Shinji Uya | Backside illuminated imaging device, semiconductor substrate, imaging apparatus and method for manufacturing backside illuminated imaging device |
| JP2009070947A (en) * | 2007-09-12 | 2009-04-02 | Fujifilm Corp | Solid-state imaging device and manufacturing method thereof |
| US20150054113A1 (en) * | 2012-06-27 | 2015-02-26 | Panasonic Intellectual Property Management Co., Ltd. | Solid-state image sensing device and production method for same |
-
2020
- 2020-09-01 CN CN202010900406.0A patent/CN111987117A/en active Pending
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03116840A (en) * | 1989-09-29 | 1991-05-17 | Sony Corp | Charge transfer device |
| JPH04280680A (en) * | 1991-03-08 | 1992-10-06 | Sony Corp | S0lid-state image pickup device |
| US5432363A (en) * | 1992-01-30 | 1995-07-11 | Matsushita Electric Industrial Co., Ltd. | Solid-state image pickup device and manufacturing method of the same |
| US5591997A (en) * | 1995-01-17 | 1997-01-07 | Eastman Kodak Company | Low capacitance floating diffusion structure for a solid state image sensor |
| US5904494A (en) * | 1996-04-09 | 1999-05-18 | Nec Corporation | Fabrication process for solid-state image pick-up device with CCD register |
| JP2002270810A (en) * | 2001-03-08 | 2002-09-20 | Sharp Corp | Solid-state image sensor |
| US20040031976A1 (en) * | 2002-08-19 | 2004-02-19 | Fuji Photo Film Co.,Ltd. | Semiconductor device and its manufacture |
| US20080283726A1 (en) * | 2006-09-20 | 2008-11-20 | Shinji Uya | Backside illuminated imaging device, semiconductor substrate, imaging apparatus and method for manufacturing backside illuminated imaging device |
| JP2009070947A (en) * | 2007-09-12 | 2009-04-02 | Fujifilm Corp | Solid-state imaging device and manufacturing method thereof |
| US20150054113A1 (en) * | 2012-06-27 | 2015-02-26 | Panasonic Intellectual Property Management Co., Ltd. | Solid-state image sensing device and production method for same |
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Application publication date: 20201124 |