Fin Field-Effect Transistor Strain Preservation via Oxide Conversion
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Solution Overview
Problem
Strain relaxation at the edges of silicon germanium or silicon fins in semiconductor devices reduces the performance benefits of strain engineering, leading to device degradation and variation.
Innovation Solution
A method involving patterning a strained semiconductor layer into fins, forming dummy gates and spacer layers, growing source/drain regions, and converting parts of the fins into oxide to maintain strain without edge relaxation, using a process that includes epitaxial growth, hardmask patterning, and low-temperature annealing to form silicon germanium oxide regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If silicon germanium or silicon fins are physically cut into desired lengths to meet design requirements, then the fins can be formed with precise dimensions, but strain relaxes at fin ends near where cuts are made, reducing the benefits provided by strain and causing device degradation and variation
Solution Approach 1:
The patent extracts the problematic fin ends that cause strain relaxation and transforms them into oxide material. By converting the fin ends into oxide, the strained channel region is preserved while still achieving the desired fin length, thus resolving the contradiction between precise dimensioning and strain preservation
Solution Approach 2:
The patent changes the material parameter of the fin ends from semiconductor material (silicon or silicon germanium) to oxide material through thermal oxidation. This parameter change eliminates strain relaxation at the fin ends while maintaining the electrical functionality of the strained channel region
2Reliability
If strain engineering is applied to increase device performance, then device performance is improved, but strain relaxation at edges reduces the benefits and causes device degradation
Solution Approach 1:
The patent converts the harmful effect of strain relaxation at fin ends into a beneficial isolation region. The oxide material formed at the fin ends provides both strain preservation for the channel and electrical isolation, thus converting a problem into a solution that enhances device performance
Solution Approach 2:
The patent applies different material properties to different regions: the channel region maintains strained semiconductor material for high performance, while the fin end regions are converted to oxide for strain preservation and isolation. This local differentiation resolves the contradiction between performance and strain stability
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 preserves strain in semiconductor devices, preventing edge relaxation and enhancing performance by maintaining compressive or tensile strain in fin field-effect transistors, thereby reducing device degradation and variation.
Implementation Method 1
patterning a strained semiconductor layer on a substrate into at least one strained fin
Implementation Method 2
growing a plurality of source/drain regions on exposed portions of the at least one strained fin
Implementation Method 3
low-temperature annealing to form silicon germanium oxide regions
Implementation Method 4
converting the part of the at least one strained fin between the plurality of dummy gates into at least one oxide
Data Source
AI summary
A method for manufacturing a semiconductor device includes patterning a strained semiconductor layer on a substrate into at least one strained fin, forming a plurality of dummy gates spaced apart from each other on the at least one strained fin, forming a spacer layer on the plurality of dummy gates, and on part of the at least one strained fin between the plurality of dummy gates, growing a plurality of source/drain regions on exposed portions of the at least one strained fin, removing the spacer layer from the part of the at least one strained fin between the plurality of dummy gates, and converting the part of the at least one strained fin between the plurality of dummy gates into at least one oxide.