Source/Drain Germanium Gradient Contacts for Lower FET Resistance
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Solution Overview
Problem
The performance of field-effect transistors (FETs) is affected by unnecessary electrical resistance in the flowpath due to variations in the source/drain structures of p-channel and n-channel FETs, leading to performance differentials between the two types.
Innovation Solution
A semiconductor structure with source/drain components having varying germanium contents, where a first component with a lower germanium content is in direct contact with the wafer and a second component with a higher germanium content is in contact with the first contact, extending along two opposing sides, and recesses are formed to enhance contact area and reduce resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a uniform source/drain structure is used for both p-channel and n-channel FETs, then manufacturing is simplified, but performance differentials arise due to different reactions to manufacturing processes
Solution Approach 1:
The source/drain structure is divided into two distinct components: a first source/drain component for p-channel FETs and a second source/drain component for n-channel FETs. Each component is optimized with specific material compositions and structural characteristics tailored to the respective transistor type, allowing each to respond optimally to manufacturing processes while maintaining overall manufacturing feasibility through a systematic approach.
2Reliability
If the contact area between source/drain and contact structure is increased, then electrical contact resistance is reduced, but device complexity increases
Solution Approach 1:
The contact structure is designed to extend along two opposing sides of the source/drain component, transitioning from a single-point or single-area contact to a multi-dimensional contact arrangement. This lateral extension along opposing sides significantly increases the total contact area and reduces electrical contact resistance while maintaining a relatively simple overall structural concept that can be integrated into existing device architectures.
Data Source
AI summary
A semiconductor structure includes a wafer, a first source/drain (S/D) extending from the wafer, and a first contact connected to the first S/D. The first S/D includes a first component in direct contact with the wafer and the first contact, the first component having a first germanium content, and a second component in direct contact with the first contact, the second component having a second germanium content. The second germanium content is higher than the first germanium content.