Sinker Width Reduction via Trench Isolation
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Solution Overview
Problem
Conventional sinker formation results in large widths due to diffusion, limiting the number of laterally-adjacent devices that can be formed in a semiconductor body, as the implanted dopant width expands significantly after drive-in, consuming valuable silicon real estate.
Innovation Solution
The semiconductor structure incorporates trench isolation structures with non-conductive materials and a doped region of higher dopant concentration, where the doped region lies between the trench isolation structures, limiting lateral diffusion and reducing sinker width by forming sinkers after the trench isolation structures are established, which confines the sinker width and reduces sheet resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dopant implantation and drive-in is used to form sinkers, then low resistance current path is achieved, but sinker width expands significantly consuming silicon real estate
Solution Approach 1:
Trench isolation structures are formed before dopant implantation to pre-establish boundaries that will confine the sinker width. The trenches are etched and filled with non-conductive material prior to the drive-in process, creating physical walls that prevent lateral diffusion of dopants during subsequent thermal processing.
Solution Approach 2:
Non-conductive trench isolation structures serve as intermediary elements between adjacent doped regions. These isolation trenches act as barriers that mediate the interaction between neighboring sinkers, preventing their lateral expansion into each other's territory while still allowing the dopant to diffuse vertically to create the desired low-resistance current path.
2Reliability
If dopant drive-in is performed to achieve desired dopant concentration, then electrical conductivity is improved, but lateral diffusion increases sinker width
Solution Approach 1:
The trench isolation structures are formed in advance before the dopant drive-in process. This preliminary action creates confining walls that will restrict the lateral movement of dopants during the subsequent thermal drive-in, allowing high dopant concentrations to be achieved without proportional increases in sinker width.
Solution Approach 2:
The trench isolation structures create localized regions with different properties - the trenches themselves are non-conductive and act as barriers, while the regions between trenches allow for high dopant concentration. This local differentiation enables controlled dopant distribution where concentration is high where needed but lateral spread is prevented by the isolated trench regions.
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 reduces sinker width by approximately half, making it independent of the required vertical depth and allowing for more devices to be formed, while also reducing sheet resistance by limiting lateral diffusion within the trench isolation structures.
Implementation Method 1
limiting lateral diffusion and reducing sinker width by forming sinkers after the trench isolation structures are established
Data Source
AI summary
Forming a semiconductor structure by forming a plurality of trenches in a semiconductor material, forming a plurality of non-conductive structures in the plurality of trenches, and forming a doped region of the first conductivity type. The plurality of trenches are spaced apart from each other, have substantially equal depths, and include a first trench and a second trench. The plurality of non-conductive structures include a first non-conductive structure in the first trench and a second non-conductive structure in the second trench. The doped region is formed between the first non-conductive structure and the second non-conductive structure. No region of a second conductivity type lies horizontally in between the first non-conductive structure and the second non-conductive structure.