CN-122028482-A - Laterally diffused metal oxide semiconductor and method of manufacturing the same

Abstract

The invention discloses a lateral diffusion metal oxide semiconductor and a manufacturing method thereof, wherein the lateral diffusion metal oxide semiconductor comprises a plurality of fin parts which are arranged at intervals, each fin part is provided with a concave area, shallow trench isolation structures positioned on the concave areas form a thick oxide layer, a grid electrode passes through the fin parts, the thick oxide layer is close to one side of the grid electrode and partially overlaps with the grid electrode, a source electrode and a drain electrode are respectively positioned at each fin part at two sides of the grid electrode, and the thick oxide layer extends from the grid electrode to the drain electrode.

Inventors

• LIU GUANLIANG
• CHEN JIANHONG

Assignees

• 联华电子股份有限公司

Dates

Publication Date

20260512

Application Date

20241122

Priority Date

20241111

Claims (19)

1. 1. A laterally diffused metal oxide semiconductor comprising: the substrate is provided with a plurality of fin parts which are arranged at intervals in a first direction and extend towards a second direction, wherein each fin part is provided with a concave area; Shallow trench isolation structures surrounding the fin portions, wherein the shallow trench isolation structures located on the recessed regions form a thick oxide layer; A gate extending beyond the fins in the first direction, the gate having a first side and a second side on both sides of the second direction, wherein the thick oxide layer is adjacent to the second side, the gate partially overlapping the thick oxide layer on each fin in a direction perpendicular to the substrate, and And a source and a drain respectively located in each of the fins on the first side and the second side, wherein the thick oxide extends from the second side of the gate to the drain.
2. 2. The ldmos of claim 1 further comprising a P-well in each of said fins adjacent to said first side.
3. 3. The ldmos of claim 1 further comprising an N-type drift region in each of said fins adjacent to said second side.
4. 4. The ldmos of claim 3 wherein the boundary of said N-type drift region is located below said thick oxide layer.
5. 5. The ldmos of claim 1 further comprising a base in each of said fins outside of said source.
6. 6. The ldmos of claim 5 further comprising a source epitaxial layer and a base epitaxial layer on each of the fins on the first side, the source epitaxial layer being located between the gate and the base epitaxial layer, the source being located in the source epitaxial layer, the base being located in the base epitaxial layer.
7. 7. The ldmos of claim 1 further comprising a drain epitaxial layer in each of the fins on the second side, the thick oxide layer being between the gate and the drain epitaxial layer, the drain being in the drain epitaxial layer.
8. 8. The ldmos of claim 1, further comprising a gate oxide layer between the gate and the fins, the gate oxide layer being directly connected to the thick oxide layer.
9. 9. The ldmos of claim 8 wherein the top surface of the gate oxide layer is higher than the top surface of the thick oxide layer.
10. 10. The ldmos of claim 8 wherein the top surface of the gate oxide layer is lower than the top surface of the thick oxide layer.
11. 11. The ldmos of claim 8 wherein a top surface of the gate oxide layer is flush with a top surface of the thick oxide layer.
12. 12. The ldmos of claim 8 further comprising an N-type drift region in each of said fins adjacent to said second side, wherein a boundary of said N-type drift region is located below said gate oxide layer.
13. 13. The ldmos of claim 1 wherein the gate is made of polysilicon or metal.
14. 14. A method of fabricating a laterally diffused metal oxide semiconductor comprising: providing a substrate, wherein a plurality of fin parts are arranged at intervals in a first direction and extend towards a second direction; Performing a first photoetching process to reduce the heights of the fin parts in the concave area; forming a dielectric layer on the fin parts, wherein the dielectric layer on the fin parts in the concave region forms a thick oxide layer; Performing a second photoetching process to reduce the height of the dielectric layer which is not positioned in the concave region, so that the dielectric layer is changed into a shallow trench isolation structure, and the fin parts which are not positioned in the concave region protrude from the shallow trench isolation structure; forming a gate extending across the fins in the first direction, wherein the gate has a first side and a second side on both sides of the second direction, wherein the thick oxide layer is adjacent to the second side, the gate partially overlaps the thick oxide layer on each fin in a direction perpendicular to the substrate, and A source and a drain are formed in each of the fins on the first side and the second side, respectively.
15. 15. The method of claim 14, further comprising forming P-type wells and N-type drift regions in the fins, wherein the P-type wells are adjacent to the first side and the N-type drift regions are adjacent to the second side.
16. 16. The method of claim 14, further comprising forming a base in each of said fins outside said source.
17. 17. The method of claim 16, further comprising forming a source epitaxial layer and a base epitaxial layer on each of the fins on the first side, the source epitaxial layer being located between the gate and the base epitaxial layer, the source being formed in the source epitaxial layer, the base being formed in the base epitaxial layer.
18. 18. The method of claim 14, further comprising forming a drain epitaxial layer in each of the fins on the second side, the thick oxide layer being located between the gate and the drain epitaxial layer, the drain being formed in the drain epitaxial layer.
19. 19. The method of claim 14, further comprising forming a gate oxide layer on the fin surfaces prior to forming the gate, the gate oxide layer being directly connected to the thick oxide layer.

Description

Laterally diffused metal oxide semiconductor and method of manufacturing the same Technical Field The present invention relates to a laterally diffused metal oxide semiconductor (LATERALLY DIFFUSED METAL OXIDE SEMICONDUCTOR, LDMOS), and more particularly, to a laterally diffused metal oxide semiconductor having different fin heights (fin) and a method of fabricating the same. Background Laterally Diffused Metal Oxide Semiconductor (LDMOS) is a power field effect transistor that is commonly used in high voltage, high power rf applications, such as power amplifiers in mobile communication system base stations, to maintain stable operation and reliability at very high breakdown voltages. The LDMOS is characterized in that a layer of thick oxide layer, such as a field oxide layer (field oxide) or a Shallow Trench Isolation (STI) structure, is arranged below a grid part close to a drain end, so that the situation that breakdown is easy to occur due to electric field concentration on the surface of a drift region at the tail end of a channel is avoided. Furthermore, by controlling the doping concentration of the two sides of the transverse PN junction and the longitudinal PN junction in the LDMOS and the thickness of the drift region (drift), the drift region can be completely depleted before the transverse junction reaches the critical breakdown voltage, thereby achieving the effect of reducing the surface electric field (RESURF) and greatly improving the breakdown voltage of the drain terminal. However, if the LDMOS is to be fabricated in the form of a fin field effect transistor (FinFET), it is difficult to form the thick oxide structure, because the thick oxide is typically formed by reacting the silicon substrate surface with oxygen by thermal oxidation, and the fin structure has more boundaries and corners than planar, and the stress distribution is complex, and these factors make it difficult to form a thick oxide layer with uniform thickness on the fin structure. Accordingly, those skilled in the art need to improve the structure and fabrication process of the conventional LDMOS to solve the above-mentioned problems. Disclosure of Invention In view of the foregoing problems encountered in the prior art, the present invention proposes a novel Laterally Diffused Metal Oxide Semiconductor (LDMOS) structure, which is characterized in that the purpose of forming the thick oxide layer by a deposition process is achieved by reducing the fin height of the thick oxide layer region. The thick oxide layer formed by the method has uniform thickness, meets the requirement of a high-voltage or high-power field effect transistor, can be finely adjusted by changing the height of the fin part and the deposited thickness in the manufacturing process, and is more convenient for manufacturing LDMOS elements with different on-resistance (RDS (on)) and Breakdown Voltage (BVD) so as to be suitable for the application of the LDMOS elements in different aspects. The invention provides a laterally diffused metal oxide semiconductor, which comprises a substrate, a shallow trench isolation structure, a grid, a thick oxide layer, a grid and a source electrode, wherein the substrate is provided with a plurality of fins which are arranged at intervals in a first direction and extend towards a second direction, the shallow trench isolation structure surrounds the fins, the shallow trench isolation structure is positioned on the recessed areas and forms a thick oxide layer, the grid extends to the first direction and passes through the fins, the grid is respectively provided with a first side and a second side at two sides of the second direction, the thick oxide layer is close to the second side, the grid is partially overlapped with the thick oxide layer on each fin in a direction perpendicular to the substrate, and the source electrode and the drain electrode are respectively positioned in each fin on the first side and the second side, and the thick oxide layer extends from the second side of the grid to the drain electrode. Another aspect of the present invention is to provide a method for fabricating a laterally diffused metal oxide semiconductor, comprising providing a substrate having a plurality of fins thereon arranged at intervals in a first direction and extending in a second direction, performing a first photolithography process to reduce the height of the fins in a recess region, forming a dielectric layer on the fins, wherein the dielectric layer on the fins in the recess region forms a thick oxide layer, performing a second photolithography process to reduce the height of the dielectric layer not in the recess region, so that the dielectric layer becomes a shallow trench isolation structure, the fins not in the recess region protrude from the shallow trench isolation structure, forming a gate extending beyond the fins in the first direction, wherein the gate has a first side and a second side on both sides of the second d