Semiconductor Fin Isolation Doping for Selective Recess Etching
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Solution Overview
Problem
As semiconductor devices undergo miniaturization, the reduction in minimum feature size leads to challenges such as bending of semiconductor fins during processing, which can result in reduced processing windows and decreased manufacturing yield.
Innovation Solution
Forming isolation regions with varying impurity concentrations between semiconductor and dielectric fins, allowing for selective etching to recess these regions differently, thereby avoiding fin bending and enhancing processing windows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If minimum feature size is reduced to improve integration density, then more components can be integrated into a given area, but semiconductor fins bend during processing reducing manufacturing yield
Solution Approach 1:
The patent applies local quality by forming isolation regions with different impurity concentrations at different locations. Specifically, isolation regions between semiconductor fins have a first impurity concentration, while isolation regions between dielectric fins and semiconductor fins have a second impurity concentration. This local differentiation allows selective etching that prevents fin bending while maintaining high integration density.
Solution Approach 2:
The patent changes the impurity concentration parameter in isolation regions to control etching behavior. By adjusting the impurity concentration (e.g., nitrogen content) in different isolation regions, the etch rate is modified locally, enabling selective recess formation that prevents semiconductor fin bending during processing.
2Ease of manufacture
If uniform isolation regions are formed between all fins, then processing is simpler, but semiconductor fins bend during subsequent processing operations
Solution Approach 1:
Instead of uniform isolation regions, the patent implements local quality by creating isolation regions with different impurity concentrations in different locations. The isolation regions between dielectric fins and semiconductor fins have a higher impurity concentration (second concentration) compared to isolation regions between semiconductor fins (first concentration), enabling differential etching that stabilizes fin structure.
Solution Approach 2:
The patent applies preliminary action by pre-forming isolation regions with differentiated impurity concentrations before subsequent processing steps. This preliminary differentiation of impurity concentrations prepares the structure for selective etching, preventing fin bending before it occurs during later processing operations.
3Manufacturing precision
If selective etching is performed on isolation regions, then fin bending is prevented and processing window is expanded, but additional process steps are required
Solution Approach 1:
The patent utilizes parameter changes by modifying the impurity concentration (e.g., nitrogen content) in isolation regions during deposition. This parameter differentiation enables selective etching in subsequent processing steps, achieving precise fin positioning while the added complexity is managed through controlled material deposition parameters.
Solution Approach 2:
The impurity (e.g., nitrogen) acts as an intermediary that mediates the etching process. By introducing this intermediary element at controlled concentrations in different isolation regions, the patent enables selective removal of material to prevent fin bending, with the intermediary facilitating the differential etching behavior needed for precise fin positioning.
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 improves the manufacturing yield by preventing semiconductor fin bending and expanding the processing window for subsequent operations like replacement gate and source/drain growth processes.
Implementation Method 1
The isolation regions are recessed with an etch that is selective to the impurity. This leads to greater etch selectivity of the isolation regions among the semiconductor fins as compared to the isolation regions between the dielectric fins and the semiconductor fins
Data Source
AI summary
A device includes a first semiconductor fin extending from a substrate, a second semiconductor fin extending from the substrate, a dielectric fin over the substrate, a first isolation region between the first semiconductor fin and the dielectric fin, and a second isolation region between the first semiconductor fin and the second semiconductor fin. The first semiconductor fin is disposed between the second semiconductor fin and the dielectric fin. The first isolation region has a first concentration of an impurity. The second isolation region has a second concentration of the impurity. The second concentration is less than the first concentration. A top surface of the second isolation region is disposed closer to the substrate than a top surface of the first isolation region.