Embedded Sigma Shaped Semiconductor Alloy Transistor
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Solution Overview
Problem
Current techniques for fabricating transistors with strained channel regions face challenges in maintaining mechanical stability and achieving optimal strain levels due to limitations in epitaxial growth processes, leading to variations in transistor characteristics and potential mechanical instability.
Innovation Solution
The method involves forming cavities below the gate electrode structure in a sequential manner, using epitaxial growth to introduce semiconductor materials that provide mechanical stability and allow for adjustable under-etching, enabling the formation of strain-inducing alloys with reduced offset and improved transistor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If epitaxial growth is used to form semiconductor alloys in cavities, then charge carrier mobility is enhanced through strain, but mechanical stability and process control are compromised due to limitations in the growth process
Solution Approach 1:
The cavity formation process is segmented into multiple steps: first forming a preliminary cavity, then performing selective etching to achieve the final cavity shape. This segmentation allows better control over the cavity dimensions and strain distribution, improving both manufacturing precision and the resulting charge carrier mobility
Solution Approach 2:
The patent applies different etching conditions to different regions of the cavity formation process. By using selective etching with different etchants for different crystallographic orientations, local quality is optimized to achieve precise cavity shapes that maintain mechanical stability while inducing the desired strain for enhanced mobility
2Reliability
If cavities are formed to extend below the gate electrode structure, then strain levels are increased for mobility enhancement, but mechanical stability is reduced
Solution Approach 1:
A preliminary cavity is formed first, extending below the gate electrode structure, and then selective etching is performed to achieve the final cavity configuration. This preliminary action allows the structure to be prepared in advance while maintaining mechanical stability during the process, and the final etching step optimizes the strain distribution without compromising overall structural integrity
3Speed
If channel length is reduced to increase operating speed, then performance improvement is achieved, but charge carrier mobility degrades
Solution Approach 1:
The patent changes the physical and chemical parameters of the semiconductor material by introducing strained silicon through selectively formed cavities. This parameter change (strain) directly affects the charge carrier mobility, allowing mobility enhancement even as channel length is reduced, thereby maintaining operating speed while improving carrier transport
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 allows for precise adjustment of transistor characteristics, such as strain conditions and doping profiles, enhancing charge carrier mobility and maintaining mechanical integrity, thereby improving transistor performance and reducing process-related fluctuations.
Implementation Method 1
The introduction of stress or strain engineering into integrated circuit fabrication is an extremely promising approach, since strained silicon may be considered as a new type of semiconductor material, which may enable the fabrication of fast powerful semiconductor devices
Implementation Method 2
using epitaxial growth to introduce semiconductor materials that provide mechanical stability and allow for adjustable under-etching
Data Source
AI summary
In sophisticated transistors, a specifically designed semiconductor material, such as a strain-inducing semiconductor material, may be sequentially provided in the drain region and the source region, thereby enabling a significant degree of lateral extension of the grown semiconductor materials without jeopardizing mechanical integrity of the transistor during the processing thereof. For example, semiconductor devices having different drain and source sides may be provided on the basis of sequentially provided embedded semiconductor materials.