Protective Silicon Shield for Strained SiGe Fin
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Solution Overview
Problem
The challenge is to maintain compressive strain in silicon germanium fins during semiconductor device fabrication, as strain relaxation occurs at the ends of the fins when they are cut to meet device dimensions, leading to device degradation and variation.
Innovation Solution
A protective silicon shield is formed around the circumference of the strained silicon germanium fin, with dimensions matching the desired final fin dimensions, allowing epitaxial growth within a trench to maintain strain and protect the fin from downstream fabrication processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If silicon germanium fins are cut to meet device dimensions, then the desired fin dimensions are achieved, but compressive strain is relaxed at the ends of the fins
Solution Approach 1:
The patent forms a protective silicon shield around the silicon germanium fin before any cutting or etching operations occur. This preliminary protective structure prevents strain relaxation by maintaining mechanical continuity at the fin ends during subsequent fabrication steps, allowing the fin to be cut to precise dimensions without compromising the compressive strain in the active channel region.
Solution Approach 2:
The protective silicon shield acts as a cushioning structure that absorbs the mechanical stress and strain relaxation that would otherwise occur at the fin ends during cutting operations. By providing this protective layer beforehand, the patent prevents the harmful strain relaxation effect while still allowing precise dimensioning of the fin.
2Reliability
If silicon germanium fins are used to introduce compressive strain, then device performance is improved, but the fins become vulnerable to strain relaxation during fabrication
Solution Approach 1:
The protective silicon shield serves as an intermediary structure between the silicon germanium fin and the external environment during fabrication processes. This intermediate layer protects the strained fin from mechanical disturbances that would cause strain relaxation, allowing the fin to maintain its compressive strain and enhanced device performance throughout the fabrication process.
3Productivity
If downstream fabrication processes are applied to silicon germanium fins, then device manufacturing is completed, but etching and other processes cause fin degradation
Solution Approach 1:
The protective silicon shield is formed before downstream fabrication processes such as etching and deposition. This preliminary protective structure prevents direct exposure of the silicon germanium fin to harsh chemicals and physical processes, thereby preventing fin degradation and dimension control issues while still allowing the manufacturing process to be completed.
4Ease of manufacture
If the fin structure is exposed during fabrication, then processing access is achieved, but strain relaxation and degradation occur
Solution Approach 1:
The protective silicon shield provides localized protection only where needed - at the ends of the silicon germanium fin where strain relaxation would occur. The shield allows processing access to the top surface of the fin for gate formation and other operations, while simultaneously protecting the critical end regions from strain relaxation and degradation.
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 method ensures that the compressive strain is maintained throughout the silicon germanium fin, preventing relaxation and protecting it from etching, thus maintaining the desired dimensions and performance in FinFET devices.
Implementation Method 1
maintain compressive strain in silicon germanium fins during semiconductor device fabrication
Implementation Method 2
forming an enclosure structure including a second type of semiconductor material, wherein the first feature includes first feature sidewall surfaces extending around a circumference of the first feature. The enclosure structure is adjacent at least a portion of the first feature sidewall surfaces and extends around the circumference of the first feature
Data Source
AI summary
Embodiments are directed to a method of forming features of a semiconductor device. The method includes forming a first feature including a first type of semiconductor material, which can be tensile or can have compressive strain. The method further includes forming an enclosure structure including a second type of semiconductor material, wherein the first feature includes first feature sidewall surfaces extending around a circumference of the first feature. The enclosure structure is adjacent at least a portion of the first feature sidewall surfaces and extends around the circumference of the first feature.