Semiconductor Device Air Gap Trench Isolation
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Solution Overview
Problem
The existing method for manufacturing semiconductor devices with deep trench isolation (DTI) structures requires multiple processing steps, leading to increased time and cost, and is prone to pattern defects due to air gaps in the trench being exposed during wet processing, causing contaminants to enter and remain in the air gaps.
Innovation Solution
A semiconductor device manufacturing method where a trench is formed after completing the semiconductor elements, allowing for the formation of an air gap within the trench, which reduces the need for high burying properties and simplifies the process, while also enhancing isolation capacity by using a stack structure of a support substrate, buried insulating film, and semiconductor layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a trench with high aspect ratio is embedded with insulating films using conventional DTI method, then the isolation capacity is enhanced, but the processing time and cost increase due to multiple deposition and anisotropic etching steps
Solution Approach 1:
The trench is formed to reach the buried insulating film before completing the semiconductor elements. This preliminary trench formation allows subsequent insulating films to be deposited directly into the trench without requiring complex anisotropic etching steps, thereby reducing processing time while maintaining isolation capacity
Solution Approach 2:
The formation of the trench and the embedding of insulating films are combined into a simplified sequential process. The trench is formed first, then insulating films are deposited to embed the trench, eliminating the need for separate anisotropic etching steps that were previously required to widen the opening
2Reliability
If a trench with air gap is formed using conventional method, then the breakdown voltage is enhanced, but contaminants enter the air gap during wet processing causing pattern defects
Solution Approach 1:
The trench is formed and insulating films are deposited to embed the trench before completing the semiconductor elements. This preliminary embedding creates a protective structure that prevents resist and other contaminants from entering the air gap during subsequent wet processing steps
Solution Approach 2:
The insulating films are deposited in advance to surround and protect the air gap within the trench. This beforehand cushioning prevents contaminants from reaching the air gap during later processing steps, thereby maintaining the integrity of the structure and preventing pattern defects
3Manufacturing precision
If multiple insulating films are deposited and anisotropic etching is performed to embed the trench, then the embedding property is improved, but the device complexity and cost increase
Solution Approach 1:
The trench formation and insulating film embedding are combined into a simplified process where the trench is formed first and then insulating films are deposited to embed it. This merging eliminates the need for complex anisotropic etching steps, reducing process complexity while maintaining embedding quality
Solution Approach 2:
The trench is formed preliminarily before depositing insulating films. This preliminary action allows the insulating films to be deposited directly into the trench structure without requiring complex etching processes to create the embedding, thereby simplifying the overall manufacturing process
Data Source
AI summary
To provide a semiconductor device that can be manufactured using a simple process without ensuring a high embedding property; and a manufacturing method of the device. In the manufacturing method of the semiconductor device according to the invention, a semiconductor substrate having a configuration obtained by stacking a support substrate, a buried insulating film, and a semiconductor layer in order of mention is prepared first. Then, an element having a conductive portion is completed over the main surface of the semiconductor layer. A trench encompassing the element in a planar view and reaching the buried insulating film from the main surface of the semiconductor layer is formed. A first insulating film (interlayer insulating film) is formed over the element and in the trench to cover the element and form an air gap in the trench, respectively. Then, a contact hole reaching the conductive portion of the element is formed in the first insulating film.