Strained Fin Structure Formation via Epitaxial Growth
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Solution Overview
Problem
Strained fin structures in MOSFET devices are vulnerable to damage during thermal annealing processes used in forming source and drain regions, which can negate the benefits of strain-induced carrier mobility enhancement.
Innovation Solution
A method for forming gate devices over strained fin structures involves creating fin structures with strained upper portions using epitaxial growth after forming isolation and dummy gates, followed by selective etching and replacement with strained semiconductor material, ensuring strain introduction occurs after dummy gate removal and before thermal annealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal annealing is performed to form source and drain regions, then the source and drain regions are properly formed, but the strained fin structure is damaged and carrier mobility enhancement is lost
Solution Approach 1:
The strained fin structure is formed prior to the thermal annealing process that creates source and drain regions. By establishing the strained structure before exposure to high temperatures, the patent ensures that strain is introduced when the structure is most vulnerable, yet the subsequent process conditions are controlled to preserve rather than destroy the strain, thereby resolving the contradiction between maintaining strain and undergoing necessary thermal processing
2Productivity
If strain is introduced into the fin structure to enhance carrier mobility, then device efficiency increases, but the strained structure becomes vulnerable to damage during subsequent processing
Solution Approach 1:
The patent employs precise control of process parameters including temperature, pressure, and chemical composition during the formation and subsequent processing of the strained fin structure. By optimizing these parameters, the patent maintains the strained configuration stable throughout manufacturing steps, thereby preserving carrier mobility enhancement while ensuring structural reliability through careful parameter management
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 preserves the strained fin structures, maintaining enhanced carrier mobility and device efficiency while protecting them from adverse thermal annealing effects.
Implementation Method 1
introducing a strain into a crystalline structure of the exposed fin structure. In one embodiment, the strained fin structure is formed by an epitaxial growth process
Implementation Method 2
Thermal annealing is part of forming source and drain regions. It is desirable form strained structures that will not be adversely affected by various processes such as thermal annealing
Data Source
AI summary
A method for forming a semiconductor device includes forming a fin structure on a substrate, forming a shallow trench isolation region adjacent the fin structure so that an upper portion of the fin structure is exposed, forming a dummy gate over the exposed fin structure, forming an interlayer dielectric layer around the dummy gate, removing the dummy gate to expose the fin structure, and after removing the dummy gate, introducing a strain into a crystalline structure of the exposed fin structure.