Ge Concentration Control in Fin-Type Semiconductor Devices
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Solution Overview
Problem
Ge condensation in fabricating SiGe layers on insulators can lead to defects or dislocations when forming fin-type active patterns with high Ge concentrations, as it causes stress due to lattice constant differences.
Innovation Solution
A method involving the sequential formation of semiconductor layers with varying Ge concentrations, followed by thermal processing and oxidation, to create a fin-type active pattern with controlled Ge concentration and reduced stress, preventing defects and dislocations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Ge condensation is used to form SiGe layers with high Ge concentration, then the Ge concentration in the fin type active pattern can be increased, but defects and dislocations occur due to stress from lattice constant differences
Solution Approach 1:
The patent segments the Ge concentration distribution into multiple layers: a first semiconductor layer with low Ge concentration (20-40%) that serves as a stress-buffer foundation, and second semiconductor layers with high Ge concentration (60-80%) that provide the desired Ge content. This segmentation allows high Ge concentration regions to exist without causing defects, as the low Ge concentration layer absorbs the stress from lattice constant differences.
Solution Approach 2:
The patent applies local quality by creating different Ge concentration zones at different positions within the fin structure. The first semiconductor layer has low Ge concentration throughout, while the second semiconductor layers have high Ge concentration specifically where needed for device performance. This local differentiation allows high Ge concentration to be achieved in critical regions without subjecting the entire structure to high stress.
2Manufacturing precision
If multiple semiconductor layers with different Ge concentrations are formed sequentially, then the fin type active pattern can achieve controlled Ge concentration, but the manufacturing process becomes more complex
Solution Approach 1:
The patent utilizes parameter changes by varying the Ge concentration parameter across different semiconductor layers. The first semiconductor layer is formed with Ge concentration of 20-40%, while subsequent second semiconductor layers are formed with Ge concentration of 60-80%. This systematic parameter variation enables precise control over the final Ge concentration distribution in the fin type active pattern, achieving optimal device performance through controlled compositional gradients.
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 the formation of semiconductor devices with reduced defect and dislocation occurrence, enabling the fabrication of high Ge concentration SiGe layers without stress-related issues, thereby improving the reliability of semiconductor devices.
Implementation Method 1
Ge of the patterned semiconductor layers is diffused so that the preliminary fin type active patterns includes Ge at a first concentration
Implementation Method 2
Surfaces of the preliminary fin type active patterns are oxidized to form a plurality of fin type active patterns. The fin type active patterns include Ge at a second concentration that is greater than the first concentration
Data Source
AI summary
A method of fabricating a semiconductor device is provided. A first semiconductor layer including Ge at a first concentration is formed on an insulation layer. Second and third semiconductor layers are formed sequentially on the first semiconductor layer. The second and third semiconductor layers include Ge at second and third concentrations higher than the first concentration. A fin type structure is formed by patterning the insulation layer and the first to third semiconductor layers. The fin type structure is vertically protruded. A fin type active pattern is formed on the fin type structure by performing a first thermal process on the fin type structure. The fin type active pattern includes Ge at a fourth concentration higher than the first concentration and lower than the second concentration.