SiGe Transistor Channel and Source-Drain Regions for Low-Temperature Activation
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Solution Overview
Problem
Current transistor technologies face challenges in efficiently forming transistors with optimized source/drain regions and channels for improved current flow and reduced activation temperatures, particularly in integrating germanium into the channel and source/drain regions for enhanced performance.
Innovation Solution
The formation of transistors with a pair of source/drain regions having a channel in between, where the channel comprises Si1-yGey and the source/drain regions comprise Si1-xGex, with conductivity-increasing dopants activated at temperatures not exceeding 600°C, and a transistor gate construction operatively proximate the channel, allowing for reduced activation temperatures and improved current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional transistor fabrication methods are used, then manufacturing process is simpler, but activation temperature is too high and current flow is insufficient
Solution Approach 1:
The patent changes the material composition parameter by incorporating germanium (Ge) into the channel and source/drain regions, forming SiGe alloys. This material parameter change enables activation at lower temperatures (≤600°C) while improving carrier mobility and current flow characteristics, resolving the contradiction between activation temperature and manufacturing simplicity
Solution Approach 2:
The patent uses composite SiGe materials combining silicon and germanium in specific ratios (e.g., Si0.8Ge0.2, Si0.6Ge0.4) to achieve both low-temperature activation and high current flow. The composite material structure provides optimized electrical properties that neither pure silicon nor pure germanium could achieve alone, while maintaining compatibility with existing fabrication processes
2Reliability
If germanium is integrated into channel and source/drain regions, then current flow capability is enhanced, but manufacturing process complexity increases
Solution Approach 1:
The patent applies local quality by selectively forming SiGe channel regions and SiGe source/drain regions with specific germanium concentrations in different locations. The channel region has optimized Ge content for high mobility, while source/drain regions have different Ge content for optimal doping and contact properties. This localized material optimization enhances current flow without requiring complete restructuring of the entire device
Solution Approach 2:
The transistor structure is segmented into distinct SiGe channel region, SiGe source region, and SiGe drain region, each with potentially different compositions and properties. This segmentation allows independent optimization of each region's characteristics to maximize current flow while managing fabrication complexity through modular processing steps
3Reliability
If dopants are activated at high temperatures, then dopant activation is more complete, but thermal damage to other structures occurs
Solution Approach 1:
The SiGe material composition is specifically engineered to enable dopant activation at reduced temperatures (≤600°C). The germanium content in the SiGe alloy modifies the thermal properties and dopant diffusion characteristics, allowing complete dopant activation at lower temperatures than conventional silicon-based transistors, thereby avoiding thermal damage to surrounding structures
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 enables transistors with enhanced current flow capabilities and reduced activation temperatures, improving the overall performance and efficiency of the transistor structure.
Implementation Method 1
An insulator-material region is in each of the source/drain regions. The insulator-material regions individually are elongated orthogonal to the current-flow direction and are no thicker than 10 Angstroms in the current-flow direction. The insulator-material regions individually are directly against one of the pair of source/drain regions and function as a restrictor of diffusion of conductivity-modifying dopant
Data Source
AI summary
A transistor comprises a pair of source/drain regions having a channel there-between. A transistor gate construction is operatively proximate the channel. The channel comprises Si1-yGey, where “y” is from 0 to 0.6. At least a portion of each of the source/drain regions comprises Si1-xGex, where “x” is from 0.5 to 1. Other embodiments, including methods, are disclosed.