CN118231248A - Low-clamping-voltage unidirectional TVS device structure and preparation method thereof - Google Patents
Low-clamping-voltage unidirectional TVS device structure and preparation method thereof Download PDFInfo
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- CN118231248A CN118231248A CN202410221654.0A CN202410221654A CN118231248A CN 118231248 A CN118231248 A CN 118231248A CN 202410221654 A CN202410221654 A CN 202410221654A CN 118231248 A CN118231248 A CN 118231248A
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- 238000002360 preparation method Methods 0.000 title claims description 8
- 239000000758 substrate Substances 0.000 claims abstract description 25
- 238000000034 method Methods 0.000 claims abstract description 14
- 238000000151 deposition Methods 0.000 claims abstract description 11
- 229910052751 metal Inorganic materials 0.000 claims abstract description 11
- 239000002184 metal Substances 0.000 claims abstract description 11
- 238000004519 manufacturing process Methods 0.000 claims abstract description 6
- 238000002513 implantation Methods 0.000 claims description 6
- 239000002210 silicon-based material Substances 0.000 claims description 6
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical group [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 5
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical group [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 5
- 229910052785 arsenic Inorganic materials 0.000 claims description 5
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 claims description 5
- 229910052796 boron Inorganic materials 0.000 claims description 5
- 238000009792 diffusion process Methods 0.000 claims description 5
- 229910052698 phosphorus Inorganic materials 0.000 claims description 5
- 239000011574 phosphorus Substances 0.000 claims description 5
- 229910052709 silver Inorganic materials 0.000 claims description 3
- 229910052737 gold Inorganic materials 0.000 claims description 2
- 239000007943 implant Substances 0.000 claims 2
- 238000005468 ion implantation Methods 0.000 abstract description 10
- 239000000463 material Substances 0.000 abstract description 5
- 230000008569 process Effects 0.000 abstract description 5
- 238000002347 injection Methods 0.000 abstract description 4
- 239000007924 injection Substances 0.000 abstract description 4
- 239000005388 borosilicate glass Substances 0.000 description 16
- 150000002500 ions Chemical class 0.000 description 5
- 238000000137 annealing Methods 0.000 description 4
- 238000013461 design Methods 0.000 description 3
- 239000004020 conductor Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 238000004518 low pressure chemical vapour deposition Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000000206 photolithography Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
- 238000001039 wet etching Methods 0.000 description 1
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Abstract
The invention discloses a low-clamping-voltage unidirectional TVS device structure, and belongs to the field of ESD protection devices. Providing a substrate, and sequentially forming an epitaxial layer and a field oxide layer on the front surface of the substrate; defining a P region physical region on the front surface of the field oxide layer through a photomask, and injecting doping elements; after the injection is finished, depositing a BSG layer and a USG layer on the surface, and diffusing in a P region physical area under a high-temperature condition to form a P region; forming ohmic contact areas on the BSG layer and the USG layer by opening holes; and depositing metal on the front surface of the substrate to form a front electrode, thinning the back surface of the substrate, and then depositing multiple layers of metal to form a back electrode. The invention increases the BSG layer as a part of doped ion source, forms a P+ region in the shallow layer, and reduces the dynamic internal resistance and clamping voltage of the device; meanwhile, the dosage required by ion implantation can be reduced, the material and time cost of the ion implantation process can be saved, and the manufacturing cost can be reduced.
Description
Technical Field
The invention relates to the technical field of ESD protection devices, in particular to a low clamping voltage unidirectional TVS device structure and a preparation method thereof.
Background
The TVS device is a novel electronic component, is developed on the basis of a voltage-stabilizing diode, has short response time, can respond to voltage change more quickly, and can better protect circuit safety in the face of transient high-voltage impact. With the rapid development of modern ultra-large scale integrated circuits, ultra-deep submicron processes have become the mainstream of integrated circuit processing processes. In order to reduce the power consumption of the integrated circuit, the characteristic size of the main control IC chip is further reduced, the working withstand voltage of the current circuit is also reduced, and the working current is smaller and smaller. Along with the reduction of the working withstand voltage of the integrated circuit, the overvoltage protection work of the high-precision IC also puts forward higher standard requirements on the corresponding ESD protection device, and can prevent static electricity, realize low leakage current and very low clamping voltage.
Currently, few means are available for realizing the low-clamp-voltage ESD protection device, and the design of the low-clamp-voltage ESD protection device is mainly realized by adopting an SCR structure in the market. The structure is characterized by strong hysteresis, the voltage is pulled back to a lower level after the device is conducted, and the effect of reducing the clamping voltage is realized through obvious negative resistance effect.
Disclosure of Invention
The invention aims to provide a low clamping voltage unidirectional TVS device structure and a preparation method thereof, which are used for solving the problems in the background technology.
In order to solve the technical problems, the invention provides a preparation method of a low clamping voltage unidirectional TVS device structure, which comprises the following steps:
providing a substrate, and sequentially forming an epitaxial layer and a field oxide layer on the front surface of the substrate;
Defining a P region physical region on the front surface of the field oxide layer through a photomask, and injecting doping elements;
after the implantation is completed, a BSG layer and a USG layer are deposited on the surface,
Forming a P region by diffusion under the high temperature condition in the P region physical region;
forming ohmic contact areas on the BSG layer and the USG layer by opening holes;
And depositing metal on the front surface of the substrate to form a front electrode, thinning the back surface of the substrate, and then depositing multiple layers of metal to form a back electrode.
In one embodiment, the substrate is made of N-type silicon material with resistivity of 0.002-0.004ohm.cm, and the doping element is phosphorus or arsenic.
In one embodiment, the material of the epitaxial layer is an N-type silicon material, the resistivity is 0.015-0.1 Ω & cm, the doping element is phosphorus or arsenic, and the thickness of the epitaxial layer is 6-15 um.
In one embodiment, the thickness of the field oxide layer is 150 to 860nm.
In one embodiment, the doping element is boron, the implantation dose is 1E15-2E16, and the implantation energy is 50KeV-80KeV.
In one embodiment, the thickness of the BSG layer is 100nm to 200nm and the thickness of the USG layer is 150nm to 500nm.
In one embodiment, the front electrode is AlSiCu or Al, and the thickness of the front electrode is 2-5um.
In one embodiment, the back surface of the substrate is 150 μm after being thinned, and the back electrode is made of Au or Ag, and the thickness of the back electrode is 1-5 μm.
The invention also provides a low clamping voltage unidirectional TVS device structure prepared by the method.
According to the low-clamping-voltage unidirectional TVS device structure and the preparation method thereof, the BSG layer is added as a part of doped ion source, a P+ region is formed in the shallow layer, and the dynamic internal resistance and clamping voltage of the device are reduced; meanwhile, the dosage required by ion implantation can be reduced, the material and time cost of the ion implantation process can be saved, and the manufacturing cost can be reduced.
Drawings
Fig. 1 is a cross-sectional view of a low clamp voltage unidirectional TVS device structure in accordance with the present invention;
FIG. 2 is a schematic diagram of fabricating a field oxide layer on the upper surface of an N-type epitaxial layer on the front side of an N-type substrate;
FIG. 3 is a schematic illustration of a photolithographic etch defining a P region and implanting P+ ions and depositing a BSG+USG layer;
FIG. 4 is a schematic illustration of a high temperature anneal to form a P region;
FIG. 5 is a schematic illustration of lithographically etching openings to form ohmic contact regions;
FIG. 6 is a schematic illustration of forming a front electrode;
fig. 7 is a schematic diagram of thinning the back side of an N-type substrate and depositing a back side metal.
Detailed Description
The invention provides a low clamping voltage unidirectional TVS device structure and a preparation method thereof, which are described in further detail below with reference to the accompanying drawings and the specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are in a very simplified form and are all to a non-precise scale, merely for convenience and clarity in aiding in the description of embodiments of the invention.
The invention provides a low clamping voltage unidirectional TVS device structure, the cross section of which is shown in figure 1, comprising an N-type substrate, an N-type epitaxial layer, a field oxide layer, a P-type ion implantation region, a BSG (borosilicate glass) +USG structure layer, an ohmic contact region, a front electrode and a back electrode.
Providing a substrate, wherein an N-type silicon material is used as an N-type substrate, the resistivity of the N-type substrate is 0.002-0.004ohm.cm, and the doping element is phosphorus or arsenic;
Forming an N-epi of an N-type epitaxial layer on the front side of the N-type substrate in an epitaxial growth mode, wherein the N-type epitaxial layer is made of an N-type silicon material, the resistivity of the N-type epitaxial layer is 0.015-0.1 omega cm, the doping element is phosphorus or arsenic, and the epitaxial thickness is 6-15 um;
growing a field oxide layer FOX with a certain thickness on the N-type epitaxial layer, wherein the thickness of the field oxide layer is 150-860 nm, as shown in figure 2;
Defining a P region physical region on the front surface of the field oxide layer through a photomask, and injecting doping elements; wherein the injection element is boron, the injection dosage is 1E15-2E16, and the injection energy is 50KeV-80KeV;
After the implantation is completed, a BSG+USG layer is deposited on the surface by LPCVD, wherein the thickness of the BSG is 100nm-200nm and the thickness of the USG is 150nm-500nm, as shown in figure 3;
The physical region of the P region is implanted with BF 2 ions and boron element in BSG, and diffusion is carried out under the high-temperature condition to form the P region (P+/P-). Furnace tube high temperature diffusion can be selected, and the diffusion temperature is 900-1200 ℃, as shown in figure 4;
forming ohmic contact regions on the BSG and USG layers by photolithography and wet etching, as shown in fig. 5;
Depositing a front electrode, wherein metal is selected as a conductive material, alSiCu or Al is used, and the thickness of the front electrode is 2-5um;
and thinning the back surface of the N-type substrate to 150 mu m, and then depositing a plurality of layers of metal on the back surface of the N-type substrate to form a back electrode, wherein the metal is selected as a conductive material, au or Ag is used, and the metal thickness is 1-5 mu m.
The TVS device is characterized in that a P region structure (P+/P-) is formed on the front surface of a heavily doped N-type epitaxial layer through the auxiliary BF 2/B11 ion implantation of a BSG structure layer under the high-temperature annealing condition, so that a PN junction of the TVS device is formed. Compared with the traditional unidirectional TVS device structure, the BSG layer is added as a part of doped ion source, a P+ region is formed in a shallow layer, and the dynamic internal resistance and clamping voltage of the device are reduced; meanwhile, the dosage required by ion implantation can be reduced, the material and time cost of the ion implantation process can be saved, and the manufacturing cost can be reduced.
The invention focuses on the special design of forming a P region (P+/P-) structure under the high-temperature annealing condition by selecting the material specification of the N-type epitaxial layer and assisting BF 2/B11 ion implantation through a BSG structural layer. The P+ formed by the BSG structural layer in the shallow layer of the P region can adjust the junction depth of the P+ by adjusting the proportion of boron/silicon in the BSG structural layer and the annealing temperature, so that the dynamic internal resistance and the clamping voltage of the device are reduced; on the other hand, the P-formed in the P region can be subjected to ion implantation, and the junction depth of the P-can be adjusted by controlling the energy of the implanted ions, the implantation dosage and the annealing temperature, so that the device parameter breakdown voltage can be controlled. The low clamping voltage unidirectional TVS device can be adjusted and debugged in electrical performance parameters through reasonable design collocation of the low clamping voltage unidirectional TVS device and the low clamping voltage unidirectional TVS device.
The above description is only illustrative of the preferred embodiments of the present invention and is not intended to limit the scope of the present invention, and any alterations and modifications made by those skilled in the art based on the above disclosure shall fall within the scope of the appended claims.
Claims (9)
1. The preparation method of the low clamping voltage unidirectional TVS device structure is characterized by comprising the following steps:
providing a substrate, and sequentially forming an epitaxial layer and a field oxide layer on the front surface of the substrate;
Defining a P region physical region on the front surface of the field oxide layer through a photomask, and injecting doping elements;
after the implantation is completed, a BSG layer and a USG layer are deposited on the surface,
Forming a P region by diffusion under the high temperature condition in the P region physical region;
forming ohmic contact areas on the BSG layer and the USG layer by opening holes;
And depositing metal on the front surface of the substrate to form a front electrode, thinning the back surface of the substrate, and then depositing multiple layers of metal to form a back electrode.
2. The method for fabricating a low clamping voltage unidirectional TVS device structure of claim 1, wherein the substrate is an N-type silicon material having a resistivity of 0.002-0.004ohm.
3. The method for manufacturing a low clamping voltage unidirectional TVS device structure according to claim 1, wherein the epitaxial layer is made of an N-type silicon material, the resistivity is 0.015-0.1 Ω & cm, the doping element is phosphorus or arsenic, and the thickness of the epitaxial layer is 6-15 um.
4. The method for fabricating a low clamping voltage unidirectional TVS device structure of claim 1, wherein said field oxide layer has a thickness of 150-860 nm.
5. The method for fabricating a low clamp voltage unidirectional TVS device structure of claim 1, wherein said doping element is boron with an implant dose of 1E15-2E16 and an implant energy of 50KeV-80KeV.
6. The method for fabricating a low clamping voltage unidirectional TVS device structure of claim 1, wherein said BSG layer has a thickness of 100nm to 200nm and said USG layer has a thickness of 150nm to 500nm.
7. The method for manufacturing a low clamping voltage unidirectional TVS device structure according to claim 1, wherein said front electrode is AlSiCu or Al, and the thickness of said front electrode is 2-5um.
8. The method for manufacturing a low clamping voltage unidirectional TVS device structure according to claim 1, wherein a back surface of said substrate is thinned to 150 μm, said back electrode is made of Au or Ag, and a thickness is 1-5 μm.
9. A low clamp voltage unidirectional TVS device structure prepared based on the method of any one of claims 1-8.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410221654.0A CN118231248A (en) | 2024-02-28 | 2024-02-28 | Low-clamping-voltage unidirectional TVS device structure and preparation method thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202410221654.0A CN118231248A (en) | 2024-02-28 | 2024-02-28 | Low-clamping-voltage unidirectional TVS device structure and preparation method thereof |
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| CN118231248A true CN118231248A (en) | 2024-06-21 |
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| CN (1) | CN118231248A (en) |
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