FinFET Fin Width Variation for Contact Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current semiconductor device fabrication techniques face challenges in achieving optimal fin structure dimensions and contact resistance for fin field-effect transistors (FinFETs), which affect uniformity, contact landing, and overall device performance.
Innovation Solution
The method involves forming a patterned mask stack over a substrate to create fins with varying dimensions and shapes, using multiple etch processes to control fin widths and angles, and forming source/drain regions to enhance epitaxy and contact quality, thereby enlarging the fin loop bending window and improving contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional planar transistor fabrication is used, then manufacturing simplicity is maintained, but device performance and scalability are limited
Solution Approach 1:
The patent transitions from planar (2D) transistor structures to three-dimensional FinFET structures with vertical fins extending from the substrate. This dimensional change increases the effective channel area and improves device performance while enabling better scalability to smaller nodes.
Solution Approach 2:
The transistor channel is segmented into multiple vertical fins rather than a single planar channel. This segmentation increases the total channel width and improves current drive capability while maintaining control over the channel region.
2Manufacturing precision
If uniform fin widths are used, then manufacturing simplicity is maintained, but contact resistance and uniformity are compromised
Solution Approach 1:
The patent implements non-uniform fin widths where different regions of the fin structure have different widths optimized for their specific functions. The fins have wider regions for better contact landing and narrower regions for optimized channel control, achieving both improved uniformity and reduced contact resistance.
Solution Approach 2:
The fin width parameter is varied along the length of the fin structure rather than maintaining a constant width. This parameter change enables optimization of different fin regions for different functions, improving overall device performance and contact characteristics.
3Reliability
If simple contact formation is used, then manufacturing ease is maintained, but contact resistance and landing quality are insufficient
Solution Approach 1:
The patent performs preliminary formation of source and drain regions with optimized doping profiles and depths before final contact formation. This preliminary action ensures proper epitaxial growth and creates optimal conditions for low-resistance contacts, improving contact quality while managing process complexity.
Solution Approach 2:
The patent introduces intermediate layers and regions between the metal contact and the fin structure, including optimized source/drain regions and potential barrier layers. These intermediary structures mediate the electrical connection, reducing contact resistance and improving landing quality.
4Length of stationary object
If aggressive etching is used to create deep fins, then fin height is increased for better performance, but fin loop bending and structural integrity are compromised
Solution Approach 1:
The patent employs multiple sequential etching steps with different parameters rather than a single aggressive etch. Each etching step progressively deepens the fins while allowing for intermediate processes that maintain structural integrity and prevent loop bending, achieving both height and precision.
Data Source
AI summary
A FinFET device and a method of forming the same are provided. A method includes forming a patterned mask stack over a substrate, features of the patterned mask stack protecting the substrate having a uniform width. Unprotected portions of the substrate exposed by the patterned mask stack are removed to form a plurality of recesses in the substrate, unremoved portions of the substrate interposed between adjacent recesses forming a plurality of fins. Portions of the plurality of fins are removed, a width of a first fin of the plurality of fins being less than a width of a second fin of the plurality of fins.