Deep Trench Isolation Layout With Cut Corners for CMP Defect Control
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Solution Overview
Problem
Conventional semiconductor devices face challenges in achieving sufficient depth for deep trench isolation (DTI) structures to isolate adjacent devices effectively, leading to increased leakage current and chip size due to limitations in etching depth and insulating material deposition, which can result in defects during the CMP process.
Innovation Solution
The semiconductor device incorporates a wide pre-DTI structure and a narrow DTI structure with cut corners or truncations in the plan view, allowing for deeper isolation and reducing defects by maintaining the width of these structures in critical regions, thereby improving isolation characteristics and preventing air gap exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single etching step is used to form the DTI structure, then the manufacturing process is simpler, but the trench depth is insufficient to achieve adequate electrical isolation
Solution Approach 1:
The etching process is divided into two separate steps: first forming a pre-DTI structure with sufficient depth, then forming the final DTI structure with precise dimensions. This segmentation allows each step to optimize for its specific purpose, achieving both adequate depth and manufacturing precision.
Solution Approach 2:
The pre-DTI structure is formed in advance as a preliminary step before forming the final DTI structure. This preliminary action ensures that the trench reaches the necessary depth to achieve adequate electrical isolation before the final structuring step.
2Reliability
If the DTI structure extends deeply into the substrate to improve isolation, then leakage current is reduced, but the chip size increases due to larger device spacing
Solution Approach 1:
By segmenting the isolation structure into pre-DTI and DTI components with different functions, the design achieves deep isolation without requiring increased device spacing. The pre-DTI provides the depth for isolation while the DTI provides the precise dimensional control, allowing compact device layout.
3Ease of manufacture
If the DTI structure has sharp corners in plan view, then the fabrication process is simpler, but defects occur during CMP process and air gaps are exposed
Solution Approach 1:
The DTI structure incorporates truncated corners instead of sharp 90-degree angles. This asymmetric modification to the corner geometry prevents the width increase that occurs during CMP processing, eliminating air gap exposure while maintaining overall fabrication simplicity.
4Ease of manufacture
If the trench width is increased to facilitate insulating material deposition, then deposition is improved, but the isolation effectiveness is reduced
Solution Approach 1:
The isolation structure is segmented into two stages: the pre-DTI stage where wider trenches facilitate insulating material deposition, and the DTI stage where narrower trenches provide precise isolation. This segmentation allows each stage to optimize for its specific requirement.
Solution Approach 2:
The solution transitions from a single-dimension trench width optimization to a two-dimensional approach by creating a stepped structure. The pre-DTI has larger dimensions facilitating deposition, while the DTI extends deeper with smaller dimensions providing precise isolation, effectively using both horizontal and vertical dimensions.
Data Source
AI summary
Disclosed are a semiconductor device and a method of manufacturing the same. More particularly, a semiconductor device and a method of manufacturing the same are disclosed, including a device isolation structure with a pre-DTI structure and/or a DTI structure having at least one corner region with a cut shape/corner or truncation in a plan view, thereby reducing or preventing the occurrence of defects during formation of the device isolation structure and in a subsequent CMP process.