Gate-Cut Isolation Structure Mitigates Stress in Semiconductor Devices
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Solution Overview
Problem
Current gate-cut processes in semiconductor fabrication lead to defects and stress effects, causing shifts in the threshold voltage of transistors due to difficulties in removing dummy polysilicon and work function metals, resulting in asymmetric gate structures and significant current or voltage shifts.
Innovation Solution
A gate-cut isolation structure is formed concurrently with a single diffusion break (SDB) using the same insulation material, which electrically separates gate regions and mitigates stress effects by filling trenches with the same insulation material, reducing defects and process complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gate-cut process is performed to separate gate regions, then electrical separation between gate regions is achieved, but stress effects and threshold voltage shifts occur due to asymmetric gate structures
Solution Approach 1:
The gate-cut isolation structure is merged with the single diffusion break (SDB) structure, forming a unified isolation system. Both structures use the same insulation material and are formed concurrently in the same fabrication process, eliminating the need for separate processing steps and reducing overall process complexity
Solution Approach 2:
The gate-cut isolation structure uses the same insulation material as the SDB, ensuring material homogeneity throughout the isolation system. This uniform material composition eliminates interface mismatches and reduces stress effects that arise from material discontinuities
2Reliability
If dummy polysilicon and work function metals are removed during gate-cut, then gate region separation is achieved, but defects and process complexity increase
Solution Approach 1:
The gate-cut isolation structure is formed concurrently with the SDB during the same fabrication process step, before subsequent processing steps. This preliminary formation eliminates the need for later removal of dummy polysilicon and work function metals, preventing defects and simplifying the overall process
Solution Approach 2:
The need to remove dummy polysilicon and work function metals is extracted from the process by forming the gate-cut isolation structure in a way that avoids creating these problematic elements in the first place, eliminating a complex removal step
Data Source
AI summary
Certain aspects of the present disclosure generally relate to a semiconductor device with a gate-cut isolation structure. An example method of fabricating semiconductor device generally includes forming a dielectric region between a first semiconductor region and a second semiconductor region. The method also includes forming a first gate region disposed above and spanning a width of the dielectric region between the first and second semiconductor regions, wherein the first gate region is also disposed above at least a portion of the first semiconductor region and above at least a portion of the second semiconductor region. The method further includes concurrently forming an SDB and a gate-cut isolation structure, wherein the SDB intersects the first and second semiconductor regions and wherein the gate-cut isolation structure electrically separates the first gate region into a first portion associated with the first semiconductor region and a second portion associated with the second semiconductor region.