Self-Aligned Buried Power Rail With Multi-Height Trenches
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Solution Overview
Problem
Existing buried power rail formation in semiconductor devices is limited by contact overlay issues with other conductive elements, leading to reduced conductivity.
Innovation Solution
A self-aligned buried power rail with adjustable height is formed between semiconductor device regions, featuring a first portion in a gate cut trench and a second portion in a source/drain cut trench, enhancing conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional buried power rail formation is used, then the structure is simple to manufacture, but the conductivity is reduced due to contact overlay issues
Solution Approach 1:
The buried power rail is segmented into multiple portions with different heights: a first portion in the gate cut trench and a second portion in the source/drain cut trench. This segmentation allows each portion to be optimized independently for its specific function, improving overall conductivity while managing manufacturing complexity through systematic division of the structure.
Solution Approach 2:
Different portions of the buried power rail are given different local qualities through varying heights. The first portion has a first height suitable for gate cut trench contact, while the second portion has a second height optimized for source/drain cut trench contact. This local differentiation resolves contact overlay issues and improves conductivity without requiring complete restructuring.
2Reliability
If a uniform height buried power rail is used, then the manufacturing process is simpler, but contact overlay issues reduce conductivity
Solution Approach 1:
The buried power rail transitions from a static uniform height structure to a dynamic multi-height structure. The first portion and second portion have different heights that can be independently optimized, allowing the structure to adapt to different contact requirements in gate cut trenches versus source/drain cut trenches, thereby improving contact alignment precision and conductivity.
Solution Approach 2:
The solution moves from a one-dimensional uniform height approach to a multi-dimensional height variation approach. By introducing vertical dimension variation with different heights for different portions, the patent resolves contact overlay issues that cannot be solved with uniform height, improving manufacturing precision for contact alignment.
Data Source
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AI summary
A self-aligned buried power rail having an adjustable height is formed between a first semiconductor device region and a second semiconductor device region. The self-aligned buried power rail having the adjustable height has improved conductivity. Notably, the self-aligned buried power rail has a first portion having a first height that is present in a gate cut trench and a second portion having a second height, which is greater than the first height, that is present in a source/drain cut trench.