FinFET Diffusion Break Formation via Single Mask
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Solution Overview
Problem
Current techniques for forming mixed single and double diffusion break structures in fin field-effect transistors face challenges such as stress relaxation, increased cost due to multiple masks required, and difficulty in combining fin cuts, which affect device performance and complexity.
Innovation Solution
The method involves forming single and double diffusion breaks using a single lithography mask and a late cut process, allowing for retention of intrinsic stress in fins and reducing process complexity and cost by using one fin cut mask, and filling trenches with dielectric material to minimize parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple masks are used to form mixed single and double diffusion break structures, then diffusion break structures can be formed, but process complexity and cost increase
Solution Approach 1:
The patent combines the formation of both single diffusion breaks and double diffusion breaks into a single lithography mask pattern. The mask includes first regions for single diffusion breaks and second regions for double diffusion breaks, allowing both types of diffusion breaks to be formed simultaneously in one photolithography step, thereby eliminating the need for multiple separate masks and reducing process complexity
2Manufacturing precision
If multiple masks are used to form mixed single and double diffusion break structures, then diffusion break structures can be formed, but manufacturing cost increases
Solution Approach 1:
The patent combines the formation of both single diffusion breaks and double diffusion breaks into a single lithography mask pattern. The mask includes first regions for single diffusion breaks and second regions for double diffusion breaks, allowing both types of diffusion breaks to be formed simultaneously in one photolithography step, thereby eliminating the need for multiple separate masks and reducing process complexity
3Manufacturing precision
If fin cuts are combined using multiple masks, then diffusion break structures can be formed, but stress relaxation occurs affecting device performance
Solution Approach 1:
The patent performs the fin cuts at a late stage in the fabrication process, after the diffusion break structures have been formed. This late cut approach ensures that the intrinsic stress in the fins is maintained throughout the diffusion break formation process, preventing stress relaxation that would occur with earlier cutting methods, thereby preserving device performance
4Device complexity
If single lithography mask is used, then process complexity is reduced, but forming both single and double diffusion breaks becomes difficult
Solution Approach 1:
The patent applies local quality by designing the single lithography mask with different pattern regions: first regions that define single diffusion breaks and second regions that define double diffusion breaks. Each region of the mask is configured with specific geometric characteristics to produce the desired diffusion break type, allowing both single and double diffusion breaks to be formed with a single mask while maintaining manufacturing precision
Data Source
AI summary
A method of forming a semiconductor structure includes forming a plurality of fins over a substrate, at least a portion of one or more of the fins providing one or more channels for one or more fin field-effect transistors. The method also includes forming a plurality of active gate structures over the fins, forming at least one single diffusion break trench between a first one of the active gate structures and a second one of the active gate structures, and forming at least one double diffusion break trench between a third one of the active gate structures and a fourth one of the active gate structures. The double diffusion break trench has a stepped height profile in the substrate, the stepped height profile comprising a first depth with a first width and a second depth less than the first depth with a second width greater than the first width.