Extended Backside Contact Structure for 3DSFET Alignment
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Solution Overview
Problem
In high-density semiconductor devices like 3DSFETs, precise alignment and connection of backside contact plugs with interconnect structures are challenging, leading to increased device size and contact resistance due to the need for additional metal lines to compensate for misalignment.
Innovation Solution
The implementation of an extended backside contact plug structure that is not vertically overlapped by the source/drain region, connected to a backside isolation structure and backside metal lines, allowing direct alignment and connection without additional metal lines, thereby reducing device size and contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional metal lines are formed to compensate for misalignment between backside contact plug and interconnect structure, then connection reliability is improved, but device size increases and manufacturing complexity increases
Solution Approach 1:
The contact plug is extended in the horizontal plane (another dimension) rather than solely relying on vertical alignment. This dimensional change allows the contact plug to reach and connect with the interconnect structure even when precise vertical alignment is difficult to achieve, thereby improving connection reliability without requiring additional metal lines and reducing manufacturing complexity
2Reliability
If additional metal lines are formed to compensate for misalignment, then connection reliability is improved, but device size increases
Solution Approach 1:
The contact plug is extended horizontally in another dimension to achieve connection with the interconnect structure. This approach eliminates the need for additional metal lines that would increase device size, while still ensuring reliable connection through the extended contact plug structure
3Length of stationary object
If extended backside contact plug structure is implemented, then device size is reduced and manufacturing flexibility is improved, but alignment precision requirements increase
Solution Approach 1:
The contact plug is extended horizontally in another dimension, which actually reduces the need for precise vertical alignment. The horizontal extension provides a larger target area for connection, thereby reducing alignment precision requirements rather than increasing them
Solution Approach 2:
The contact plug is pre-positioned and extended to reach the interconnect structure before final connection steps. This preliminary positioning action ensures that the contact plug is already in the correct horizontal location, reducing the precision requirements for subsequent alignment operations
Data Source
AI summary
Provided is a semiconductor device which includes: a backside contact plug, formed at a back side of the semiconductor device, below a source/drain region connected to the backside contact plug, wherein the backside contact plug includes a 1st portion which is not vertically overlapped by the circuit element.