Self-Aligned Diffusion Break for Replacement Metal Gate
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Solution Overview
Problem
Current semiconductor manufacturing approaches for integrated circuits face challenges such as poor source/drain growth, contact punch-through, and device variability at the 20 nm technology node and beyond, particularly due to issues with diffusion break formation under dummy gates.
Innovation Solution
The formation of a diffusion break is shifted after source/drain formation, with a dummy gate body removal selective to a capping layer, allowing for self-aligned oxide fill material extension into the substrate, enabling facet-free and high-quality source/drain formation through RMG poly open chemical mechanical planarization and poly open planarization processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a diffusion break is formed beneath the dummy gate prior to source/drain formation, then the diffusion break provides isolation, but poor source/drain growth occurs at active region and Fin edge
Solution Approach 1:
The patent performs source/drain formation before creating the diffusion break. The sequence is: form source/drain regions with epitaxial growth, then subsequently form the diffusion break by removing dummy gate material and filling with dielectric. This preliminary action of source/drain formation eliminates the harmful effect of premature diffusion breaks on growth quality.
Solution Approach 2:
The patent inverts the conventional sequence by forming source/drain regions first and then creating the diffusion break afterward. Instead of the traditional approach of forming diffusion break before source/drain, the method reverses the order to avoid the contradiction between isolation needs and growth quality.
2Manufacturing precision
If existing solutions are used to form diffusion breaks, then device variability is reduced, but standard cell width increases by at least 1 contacted poly pitch
Solution Approach 1:
The patent applies diffusion breaks locally only where needed for isolation, rather than uniformly across the entire device structure. The diffusion break is formed selectively beneath the dummy gate region while maintaining compact cell dimensions, achieving local isolation quality without increasing overall standard cell width.
3Reliability
If existing solutions are used to form diffusion breaks, then isolation is provided, but adequate coverage for Rx and Fin tuck is not ensured
Solution Approach 1:
The patent performs Rx and Fin formation with proper coverage before creating the diffusion break. The preliminary formation of these structures ensures adequate coverage is established, and the subsequent diffusion break formation does not compromise this coverage while providing necessary isolation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach eliminates device variability and ensures adequate coverage for source/drain regions and Fin structures, improving device yield and performance by maintaining the capping layer during dummy gate etching and using oxide fill material to align the diffusion break with the gate, thus enhancing semiconductor device reliability.
Implementation Method 1
removing the dummy gate body selective to a sidewall section of the capping layer
Implementation Method 2
filling the opening with an oxide fill material
Implementation Method 3
RMG poly open chemical mechanical planarization (POC) and poly open planarization (POP)
Data Source
AI summary
Embodiments of the invention provide approaches for replacement metal gate (RMG) diffusion break formation. Specifically, a diffusion break is created after source/drain (S/D) formation, thereby allowing facet free and high quality S/D formation. A dummy gate body is removed selective to a sidewall section of a capping layer and a GOx layer formed over a substrate, and the opening is then extended through the GOx layer and into the substrate by etching the dummy gate body selective to the sidewall section of the capping layer. Retaining the capping layer during the dummy gate body etch enables the diffusion break to be self-aligned to the gate and eliminates device variability due to S/D volume variations. Processing then continues with RMG poly open chemical mechanical planarization (POC) and poly open planarization (POP).