STI Formation in Hybrid SOI-Bulk Semiconductor Devices
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Solution Overview
Problem
The existing process for manufacturing semiconductor integrated circuit devices with a hybrid SOI structure faces challenges due to significant height differences between the STI insulative film and the semiconductor substrate in the bulk device region, which affects device isolation and fine device manufacturing.
Innovation Solution
The method involves removing the BOX and SOI layers in the bulk device region before forming the STI region, allowing the STI region to extend through the BOX layer in the SOI device region, thereby reducing step height and improving device isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the BOX layer and SOI layer are removed in the bulk device region before forming the STI region, then the step height difference between the STI insulative film and the semiconductor substrate is reduced, but the process complexity increases
Solution Approach 1:
The BOX layer and SOI layer are removed in advance before forming the STI region. This preliminary removal action allows the STI trench to be formed directly to the substrate surface in the bulk device region, eliminating the need for deep trenches through the BOX layer and thereby reducing the step height difference between the STI insulative film and the substrate.
Solution Approach 2:
The device region is divided into two types: bulk device regions where the BOX and SOI layers are removed, and SOI device regions where the BOX and SOI layers are retained. This segmentation allows different STI formation approaches in different regions, optimizing the step height in bulk regions while maintaining SOI structure in SOI regions.
2Reliability
If the STI region is formed to extend through the BOX layer in the SOI device region, then device isolation is improved, but the step height difference increases
Solution Approach 1:
Different STI formation strategies are applied to different device regions. In bulk device regions, the BOX and SOI layers are removed before STI formation to minimize step height. In SOI device regions, the BOX and SOI layers are retained and the STI region extends through the BOX layer to achieve deep isolation. This local differentiation resolves the contradiction by optimizing for device isolation in SOI regions while controlling step height in bulk regions.
Data Source
AI summary
A method for manufacturing a semiconductor integrated circuit device includes the step of forming an SOI device region and a bulk device region on an SOI type semiconductor wafer. The method includes: removing a BOX layer and an SOI layer in a bulk device region; and thereafter forming an STI region in both the SOI device region and the bulk device region. In the method, the STI region in the SOI device region is formed to extend through the BOX layer.