GeSn Source/Drain Surface Composition for Lower Contact Resistance
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Solution Overview
Problem
As semiconductor devices shrink to nanometer technology process nodes, contact resistance increases due to reduced electrical contact area, impacting device performance.
Innovation Solution
The method involves forming a semiconductor device with a gate electrode structure and source/drain regions made of alloy semiconductor materials, where radiation annealing is used to create a surface region with a higher concentration of a second alloy element than the internal region, thereby reducing contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If semiconductor devices are shrunk to nanometer technology process nodes to increase device density, then device density is improved, but contact resistance increases due to reduced electrical contact area
Solution Approach 1:
The patent applies local quality by creating a surface region with higher concentration of second alloy element (e.g., Sn) specifically at the contact interface, while the bulk material maintains its original composition. This localized compositional modification reduces contact resistance at the critical contact area without changing the overall device dimensions, thereby resolving the contradiction between high device density and low contact resistance.
Solution Approach 2:
The patent changes the compositional parameter of the alloy semiconductor material by creating a gradient structure where the surface region has a higher concentration of the second alloy element compared to the bulk. This parameter change (compositional gradient) is achieved through selective irradiation or deposition processes, enabling reduced contact resistance while maintaining the nanometer-scale device dimensions for high density.
2Reliability
If radiation annealing is used to create a surface region with higher concentration of second alloy element, then contact resistance is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by forming the alloy semiconductor material layer with the desired compositional gradient before subsequent processing steps. The surface region is pre-modified with higher concentration of the second alloy element through radiation annealing or selective deposition, so that when contacts are formed later, the low contact resistance is already established, simplifying the overall manufacturing flow.
Solution Approach 2:
The patent replaces traditional mechanical or thermal annealing processes with radiation-induced annealing to create the compositional gradient. This substitution allows for more precise control of the surface region composition and enables the formation of the alloy structure with higher second element concentration at the surface without requiring complex multi-step thermal processing, thereby reducing manufacturing complexity.
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 contact resistance and improves electron flow in semiconductor devices by creating a Sn-rich surface region in GeSn source/drain regions, which enhances dopant activation and strain in the channel region.
Implementation Method 1
The unmasked portion of the alloy semiconductor material layer not covered by the mask is irradiated with radiation from a radiation source to transform the alloy semiconductor material layer so that a surface region of the unmasked portion of the alloy semiconductor material layer has a higher concentration of the second element than an internal region of the unmasked portion of the alloy semiconductor material layer
Data Source
AI summary
A semiconductor device includes a first layer that includes a first semiconductor material disposed on a semiconductor substrate, and a second layer of a second semiconductor material disposed on the first layer. The semiconductor substrate includes Si. The first semiconductor material and the second semiconductor material are different. The second semiconductor material is formed of an alloy including a first element and Sn. A surface region of an end portion of the second layer at both ends of the second layer has a higher concentration of Sn than an internal region of the end portion of the second layer. The surface region surrounds the internal region.