CN-119650510-B - Trench isolation structure, preparation method thereof and semiconductor device

CN119650510BCN 119650510 BCN119650510 BCN 119650510BCN-119650510-B

Abstract

The invention discloses a trench isolation structure, a preparation method thereof and a semiconductor device. And filling at least the inside of the trench with a sacrificial layer, wherein the filled sacrificial layer exposes a trench sidewall at a partial height in a depth direction from a port of the trench to the inside of the trench. At least a first oxide film layer is formed above the side wall of the groove and the sacrificial layer in the groove, a first part of the first oxide film layer is formed on the side wall of the groove, a gap is formed in the first part, and a second part is formed at the bottom of the gap and on the sacrificial layer. A window is formed over the second portion, the window exposing a portion of the sacrificial layer. The sacrificial layer within the trench is removed based on the window. And filling the second oxide film layer in the gap in the first part until the second oxide film layer completely fills the gap. Therefore, the invention can simplify the preparation process of the trench isolation structure, reduce the preparation difficulty and cost and improve the performance of the semiconductor device.

Inventors

LAN ZONGJIN
WU JIANBO

Assignees

杭州富芯半导体有限公司

Dates

Publication Date: 20260512
Application Date: 20241209

Claims (15)

1. A method for fabricating a trench isolation structure, comprising: providing a semiconductor substrate, wherein the semiconductor substrate comprises a groove; Filling a sacrificial layer in at least the trench, wherein the sacrificial layer is completely filled in the trench, the sacrificial layer is etched back into the trench, and the depth of the trench occupied by the etching back depth is controlled to be 1% -4% so as to expose part of the trench side wall at the port of the trench; Forming a first oxide film layer at least above the trench sidewall and the sacrificial layer in the trench, wherein the first oxide film layer comprises a first part and a second part, the first part is formed on the trench sidewall, and a gap penetrating through the first part in the depth direction of the trench is formed in the first part; forming a window on the second portion, the window exposing a portion of the sacrificial layer; Removing the sacrificial layer in the groove based on the window; and filling a second oxide film layer in the gap in the first part until the second oxide film layer completely fills the gap, and forming a seal at the port of the groove.
2. The method of claim 1, further comprising, prior to filling at least an interior of the trench with a sacrificial layer: And forming an oxide layer on the inner wall of the groove and the surface of the semiconductor substrate.
3. The method of claim 1, wherein the sacrificial layer is a photoresist layer or a bottom anti-reflective coating.
4. The method of claim 1, wherein forming a first oxide film layer over at least exposed trench sidewalls of the trench and the sacrificial layer within the trench comprises: and depositing the first oxide film layer by adopting a low-temperature oxide film process.
5. The method of claim 1 or 4, wherein forming a first oxide film layer over at least the trench sidewall and the sacrificial layer in the trench comprises: The thickness of the first portion formed is greater than the thickness of the second portion formed.
6. The method of fabricating a trench isolation structure according to claim 1, wherein the step of forming a window in the second portion comprises: and etching the first oxide film layer in the groove in an anisotropic etching mode to enable the transverse etching rate to be smaller than the longitudinal etching rate so as to remove at least part of the second part and form the window.
7. The method of claim 6, wherein the step of etching the first oxide film layer in the trench by anisotropic etching comprises: And anisotropically etching the first oxide film layer positioned in the groove in a self-alignment mode.
8. The method of claim 1, wherein the step of removing the sacrificial layer in the trench based on the window comprises: and removing the sacrificial layer by adopting wet etching and/or ashing process.
9. The method of claim 1, wherein the step of filling the gaps in the first portion with the second oxide film layer until the second oxide film layer completely fills the gaps comprises: And filling the second oxide film layer in the gap in the first part by adopting a chemical vapor deposition process.
10. The method of manufacturing a trench isolation structure according to claim 1 or 9, wherein the step of filling the gap in the first portion with the second oxide film layer until the second oxide film layer completely fills the gap comprises: controlling the deposition rate of the second oxide film layer to be between 2000A/min and 4000A/min.
11. The method of claim 1, wherein the step of filling the gaps in the first portion with the second oxide film layer until the second oxide film layer completely fills the gaps further comprises: and flattening the interface where the second oxide film layer is located.
12. The method of claim 1, wherein the semiconductor substrate comprises a wafer and an epitaxial layer formed on the wafer, the epitaxial layer comprising the trench.
13. A trench isolation structure, characterized in that the trench isolation structure is formed by the method for manufacturing a trench isolation structure according to any one of claims 1 to 12, the trench isolation structure comprising: a semiconductor substrate; a trench extending from a surface of the semiconductor substrate toward an inner direction of the semiconductor substrate, wherein a first oxide film layer is formed on a trench sidewall at a port of the trench; The sealing device comprises a groove, a sealing opening, a first oxide film layer, a second oxide film layer and a first electrode, wherein the sealing opening is positioned at a port of the groove and seals the port of the groove; And a void structure located within the trench below the seal.
14. The trench isolation structure of claim 13 wherein the height of the seal occupies 1% -4% of the depth of the trench.
15. A semiconductor device comprising the trench isolation structure of any of claims 13-14.

Description

Trench isolation structure, preparation method thereof and semiconductor device Technical Field The invention relates to the technical field of semiconductor device manufacturing, in particular to a trench isolation structure, a manufacturing method thereof and a semiconductor device. Background With the development of semiconductor technology, the feature size of devices in integrated circuits is smaller and the speed of devices and systems is increased, and particularly, after the semiconductor process enters a deep submicron stage, the isolation process is becoming more and more important. Currently, DTI (DEEP TRENCH Isolation) technology is widely applied to microelectronic devices, integrated circuits, sensors, optoelectronic devices and the like, so as to improve chip performance, reduce chip power consumption, and improve chip integration level and reliability. Typically, DTI structures include trenches or gaps formed in isolation regions in a semiconductor substrate that require a complete filling of an oxide layer to prevent electrical coupling adjacent device structures. However, since the deep trench has a high aspect ratio, it has a high process difficulty in completely filling the oxide layer in the deep trench, and it is difficult to complete the filling of the deep trench without generating random voids or gaps. And the deep trench after the oxide layer is completely filled can also increase the internal stress of the device, and the performance of the device is affected. Disclosure of Invention In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a trench isolation structure, a method for manufacturing the same, and a semiconductor device, so as to simplify a manufacturing process of the trench isolation structure, reduce manufacturing difficulty and cost, and improve performance of the semiconductor device. To achieve the above and other related objects, the present invention provides a method for manufacturing a trench isolation structure, including: Providing a semiconductor substrate, wherein the semiconductor substrate comprises a groove; filling at least the inside of the trench with a sacrificial layer, wherein the filled sacrificial layer exposes a trench sidewall at a partial height in a depth direction from a port of the trench to the inside of the trench; Forming a first oxide film layer at least above the side wall of the groove and the sacrificial layer in the groove, wherein the first oxide film layer comprises a first part and a second part, the first part is formed on the side wall of the groove, and a gap penetrating through the first part in the depth direction of the groove is formed in the first part; Forming a window on the second portion, the window exposing a portion of the sacrificial layer; removing the sacrificial layer in the groove based on the window; and filling a second oxide film layer in the gap in the first part until the second oxide film layer completely fills the gap, and forming a seal at the port of the groove. According to an aspect of the present invention, there is also provided a trench isolation structure formed by the method of manufacturing a trench isolation structure as described above. According to an aspect of the present invention, there is also provided a semiconductor device including the trench isolation structure described above. Compared with the prior art, the trench isolation structure, the preparation method thereof and the semiconductor device at least have the following steps The beneficial effects are that: The preparation method of the trench isolation structure comprises the steps of providing a semiconductor substrate, wherein the semiconductor substrate comprises a trench. And filling at least the inside of the trench with a sacrificial layer, wherein the filled sacrificial layer exposes a trench sidewall at a partial height in a depth direction from a port of the trench to the inside of the trench. At least a first oxide film layer is formed above the side wall of the groove and the sacrificial layer in the groove, the first oxide film layer comprises a first part and a second part, the first part is formed on the side wall of the groove, a gap penetrating through the first part in the depth direction of the groove is formed in the first part, and the second part is formed at the bottom of the gap and on the sacrificial layer. A window is formed over the second portion, the window exposing a portion of the sacrificial layer. The sacrificial layer within the trench is removed based on the window. And filling a second oxide film layer in the gap in the first part until the second oxide film layer completely fills the gap, and forming a seal at the port of the groove. Therefore, the seal is formed only at the port of the groove, and a part of void structure is reserved below the seal, so that the groove isolation structure formed in the invention can reduce capacitance, impr