Source Drain Contacts for Semiconductor Devices
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Solution Overview
Problem
The semiconductor industry faces challenges in shrinking the size and increasing the speed of finFETs, particularly due to issues with contact resistance and capacitance in the source/drain regions, which affect the performance of semiconductor devices.
Innovation Solution
The formation of contacts that penetrate deeply into the epitaxial source/drain regions, increasing the surface area of contact and using a material composition with low resistivity to reduce the source/drain contact resistance, while maintaining a specific thickness and composition in different regions to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional contact formation methods are used, then the manufacturing process is simple, but the contact resistance is high
Solution Approach 1:
The contact structure transitions from a planar surface contact to a three-dimensional configuration where contacts extend vertically into the source/drain regions. This dimensional change increases the contact surface area from a two-dimensional interface to a multi-faceted three-dimensional interface, thereby reducing contact resistance without significantly complicating the manufacturing process
Solution Approach 2:
The contact structure is formed by nesting multiple material layers within each other, with contacts extending through different regions and depths. This nested configuration allows for optimized electrical connection while maintaining a compact structure that does not substantially increase manufacturing complexity
2Reliability
If contact surface area is increased, then contact resistance is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The contact structure is formed by preliminary patterning and etching steps that define the contact footprint and depth before final material deposition. This preliminary action establishes precise geometric boundaries that guide subsequent manufacturing steps, ensuring consistent contact dimensions and reduced variability
Solution Approach 2:
Different regions of the contact structure have optimized local properties, with contact portions in the source region having different dimensions or material compositions than those in the drain region. This local quality optimization allows each contact portion to be tailored for its specific electrical and mechanical requirements, improving overall contact performance while managing manufacturing precision
Data Source
AI summary
A semiconductor device includes a first source/drain region and a second source/drain region disposed on opposite sides of a plurality of conductive layers. A dielectric layer overlies the first source/drain region, the second source/drain region, and the plurality of conductive layers. An electrical contact extends through the dielectric layer and the first source/drain region, where a first surface of the electrical contact is a surface of the electrical contact that is closest to the substrate, a first surface of the plurality of conductive layers is a surface of the plurality of conductive layers that is closest to the substrate, and the first surface of the electrical contact is closer to the substrate than the first surface of the plurality of conductive layers.