FinFET Epitaxial Channel Defect Segregation
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Solution Overview
Problem
FinFET fabrication faces significant performance degradation due to defects at the interface between epitaxial semiconductor material and the fin, caused by different lattice constants, which are difficult to eliminate in current methods.
Innovation Solution
A method is developed to fabricate a FinFET by forming source and drain recesses, filling them with dielectric material, removing the dummy gate, and growing epitaxial semiconductor channel material in a way that traps most defects at the bottom portion of the fin opening, leaving the top portion almost defect-free.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If epitaxial semiconductor material is grown atop the channel region, then the channel material can be formed, but defects at the interface with the fin due to different lattice constants cause significant performance degradation
Solution Approach 1:
The channel region is divided into two distinct segments: a bottom portion containing the defects from epitaxial growth and a top portion that is almost defect-free. This segmentation allows the defective region to be isolated from the active channel region, resolving the contradiction between forming epitaxial material and maintaining device performance.
Solution Approach 2:
The defective bottom portion of the channel region is selectively removed through recessing operations, extracting the harmful defects from the structure. This leaves behind an almost defect-free top portion that serves as the active channel, thereby improving device performance while maintaining the benefits of epitaxial growth.
2Quantity of substance
If epitaxial semiconductor channel material is grown in the fin opening, then channel material is formed, but most defects are generated during the growing process
Solution Approach 1:
The defect generation during epitaxial growth is converted from a harmful factor into a beneficial one by allowing defects to concentrate in the bottom portion of the fin opening. This natural defect segregation transforms the harmful growth process into a useful method for creating a defect gradient, with the almost defect-free top portion serving as the high-quality active channel.
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 effectively minimizes defects in the epitaxial semiconductor channel material, enhancing the performance of the FinFET by ensuring the top active channel regions are almost defect-free, thereby improving the overall device performance.
Implementation Method 1
growing epitaxial semiconductor channel material in the fin opening, such that at least a majority of defects associated with the growing are trapped at a bottom portion of the fin opening
Data Source
AI summary
A FinFET includes a fin and a conductive gate surrounding a top channel region of the fin, the channel region of the fin being filled with an epitaxial semiconductor channel material extending below a bottom surface of the conductive gate. The top channel region of the fin includes epitaxial semiconductor channel material that is at least majority defect free, the at least a majority of defects associated with forming the epitaxial semiconductor material in the channel region being trapped below a top portion of the channel region. The FinFET may be achieved by a method, the method including providing a starting semiconductor structure, the starting semiconductor structure including a bulk semiconductor substrate, semiconductor fin(s) on the bulk semiconductor substrate and surrounded by a dielectric layer, and a dummy gate over a channel region of the semiconductor fin(s). The method further includes forming source and drain recesses adjacent the channel region, removing the dummy gate, recessing the semiconductor fin(s), the recessing leaving a fin opening above the recessed semiconductor fin(s), and growing epitaxial semiconductor channel material in the fin opening, such that at least a majority of defects associated with the growing are trapped at a bottom portion of the at least one fin opening.