SRAM FinFET Isolation Structure for Source/Drain Contact Control
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Solution Overview
Problem
Existing semiconductor SRAMs face challenges in achieving a balance between writability and read stability due to conflicting performance requirements for pass-gate transistors, leading to issues with contact between adjacent source/drain doped regions and high contact resistance.
Innovation Solution
A method is developed to fabricate semiconductor structures with specific fin structures and isolation layers, where doping ions are implanted into the isolation structure to control the topography of source/drain regions, reducing their width and preventing contact between adjacent regions, while maintaining sufficient contact area for low resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the width of source/drain doped regions is reduced to prevent contact between adjacent regions, then reliability is improved, but manufacturing precision is worsened due to difficulty in controlling region boundaries
Solution Approach 1:
The patent introduces an isolation structure as an intermediary element positioned between adjacent source/drain doped regions. This isolation structure acts as a physical barrier and reference boundary that prevents direct contact between adjacent doped regions while providing a well-defined geometric reference for manufacturing processes, thereby solving both the reliability issue of region contact and the manufacturing precision challenge of boundary control.
2Productivity
If pass-gate transistor performance is optimized for writability, then productivity is improved, but read stability is worsened due to conflicting performance requirements
Solution Approach 1:
The patent segments the pass-gate transistor functionality by introducing separate control mechanisms for write and read operations. The isolation structure enables independent optimization of write and read paths, allowing the pass-gate transistor to be optimized for writability through controlled doping and geometry while maintaining read stability through the physical separation and isolation provided by the isolation structure.
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 performance of SRAMs by reducing contact between adjacent source/drain doped regions, enhancing writability and read stability, and minimizing contact resistance.
Implementation Method 1
implanting doping ions into the top of the initial isolation structure formed in the first region adjacent to the two first fin structures
Data Source
AI summary
A semiconductor structure includes: a base substrate; two first fin structures formed on the base substrate; an isolation structure formed on the base substrate, wherein a top surface of the isolation structure is lower than top surfaces of the two first fin structures, the isolation structure covers a portion of sidewall surfaces of the two first fin structures, the isolation structure includes a first region, located between the two first fin structures, and two second regions, and the top surface of the isolation structure formed in the first region adjacent to the two first fin structures is higher than the top surface of the isolation structure formed in the two second regions; and a plurality of source/drain openings formed in the first fin structures and having a bottom surface lower than the top surface of the isolation structure formed in the two second regions.