Backside Isolation Structure for 3DSFET Device Isolation
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Solution Overview
Problem
The formation of shallow trench isolation (STI) structures in semiconductor devices, especially in three-dimensionally-stacked field-effect transistors (3DSFETs), is complex and costly due to the long oxidation time at high temperatures, increasing manufacturing costs and complexity.
Innovation Solution
A semiconductor device with a backside isolation structure and placeholder isolation structure is introduced, eliminating the need for STI structures by using a backside contact structure and placeholder isolation structures made of silicon oxide and silicon nitride, respectively, to isolate devices, thereby reducing manufacturing time and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shallow trench isolation (STI) structures are formed in the substrate, then device isolation is achieved, but manufacturing time and cost increase due to long oxidation time at high temperature
Solution Approach 1:
The patent moves the isolation structure from the front side (traditional STI) to the back side of the semiconductor device. By forming the isolation structure on the opposite surface, the device achieves effective isolation without requiring lengthy high-temperature oxidation processes on the front side, thus reducing manufacturing time while maintaining isolation effectiveness.
Solution Approach 2:
Instead of forming isolation structures on the front side of the device as traditionally done, the patent inverts the approach by forming the isolation structure on the back side. This inversion eliminates the need for long oxidation times associated with front-side STI formation while achieving the same isolation objective.
2Reliability
If shallow trench isolation (STI) structures are formed in the substrate, then device isolation is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
By relocating the isolation structure to the back side of the device, the patent simplifies the front-side manufacturing process. The back-side isolation structure eliminates the need for complex deep and narrow trench formation and long oxidation processes on the front side, thereby reducing overall manufacturing complexity while maintaining effective device isolation.
3Ease of manufacture
If backside contact structure and placeholder isolation structure are used, then manufacturing process is simplified, but new structures and materials are required
Solution Approach 1:
The patent segments the isolation function into two parts: a backside contact structure that provides mechanical support and electrical connection, and a placeholder isolation structure that provides electrical isolation. This segmentation allows each component to be optimized independently and simplifies the overall manufacturing process by eliminating the need for traditional front-side STI formation.
Data Source
AI summary
Provided is a semiconductor device including: a 1st source/drain region and a 1st backside contact structure, vertically below the 1st source/drain region, connected to the 1st source/drain region; a 2nd source/drain region and a 1st placeholder isolation structure vertically below the 2nd source/drain region; and a backside isolation structure, on a back side of the semiconductor device, surrounding the 1st backside contact structure and the 1st placeholder isolation structure.