Semiconductor Isolation Region With Segmented Trench Etching
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Solution Overview
Problem
Conventional semiconductor manufacturing processes face challenges in achieving deep trench isolation (DTI) regions that are sufficiently deep to meet 100V breakdown voltage requirements, leading to increased leakage current and chip size due to limitations in single etching processes.
Innovation Solution
The solution involves separately forming a pre-DTI region with a larger width and a DTI region with a narrower width, both extending into the substrate, without using a separate etch stop layer, and covering the isolation region with an interlayer dielectric to prevent metal residue and simplify the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single etching process is used to form the DTI region, then the manufacturing process is simple, but the trench cannot be formed sufficiently deep to achieve 100V breakdown voltage requirements
Solution Approach 1:
The etching process is divided into two separate stages: a first etching process that forms a pre-DTI region with a first trench to a first depth, and a second etching process that forms a DTI region with a second trench to a second depth greater than the first depth. This segmentation allows each etching process to be optimized independently, achieving the required deep trench depth while maintaining process simplicity.
Solution Approach 2:
The first etching process is performed as a preliminary action to form the pre-DTI region before the second etching process forms the final DTI region. This preliminary action prepares the substrate by creating an initial trench structure that facilitates the subsequent deeper etching process, enabling achievement of the target depth for 100V breakdown voltage requirements.
2Reliability
If the trench depth is insufficient to achieve 100V breakdown voltage, then the manufacturing process remains simple, but leakage current increases and breakdown voltage characteristics deteriorate
Solution Approach 1:
The isolation structure is segmented into two regions: a pre-DTI region formed by the first etching process to a first depth, and a DTI region formed by the second etching process to a greater second depth. This segmentation ensures sufficient trench depth for 100V breakdown voltage requirements while maintaining manufacturing efficiency through optimized process steps.
Solution Approach 2:
The etching parameters are changed between the two processes: the first etching process uses parameters optimized for forming the pre-DTI region to a first depth, while the second etching process uses different parameters to extend the trench to the greater second depth required for adequate electrical isolation and breakdown voltage characteristics.
3Reliability
If the separation distance between transistor devices is increased to reduce noise transmission, then noise isolation improves, but the overall chip size increases
Solution Approach 1:
The isolation structure is segmented into a pre-DTI region and a DTI region with different depths, allowing effective noise isolation between adjacent transistor devices while maintaining compact chip size. The deeper DTI region provides superior electrical isolation compared to conventional single-depth trenches, enabling closer device spacing without compromising noise isolation performance.
4Manufacturing precision
If a separate etch stop layer is used to form the isolation region, then the isolation structure is well-defined, but the manufacturing process becomes more complex
Solution Approach 1:
The separate etch stop layer is extracted from the process by using the gate layer itself as the etch stop layer. The gate layer is deposited on the substrate, and the isolation region is formed by etching through the gate layer and into the substrate, eliminating the need for a separate etch stop layer while maintaining well-defined isolation region boundaries.
Solution Approach 2:
The gate layer serves multiple functions: it acts as both the functional gate structure and the etch stop layer for forming the isolation region. This multi-functionality simplifies the manufacturing process by eliminating the separate etch stop layer while ensuring precise isolation region definition through the gate layer's inherent properties.
5Productivity
If metals such as tungsten remain on the isolation region during contact formation, then the manufacturing process is simpler, but device reliability deteriorates due to metal contamination
Solution Approach 1:
An interlayer dielectric is deposited on the substrate to cover the isolation region as a preliminary action before contact formation. This preliminary protective layer prevents metals such as tungsten from contaminating the isolation region during subsequent contact formation processes, ensuring device reliability while maintaining manufacturing simplicity.
Solution Approach 2:
The interlayer dielectric serves as an intermediary protective layer between the isolation region and the contact formation process. This intermediary layer prevents direct contact between metals and the isolation region during manufacturing, eliminating metal contamination risks while allowing the manufacturing process to proceed efficiently.
Data Source
AI summary
Provided is a semiconductor device and a method of manufacturing the same and, more particularly, to a semiconductor device and a method of manufacturing the same seeking to simplify the manufacturing process and consequently improve efficiency and reliability by forming an isolation region (191) including a pre-DTI region (1911) and a DTI region (1913) in and/or on a substrate before depositing an interlayer dielectric, thereby avoiding a need for a separate etch stop layer.