Epitaxial Source/Drain Shape Control for Lower Contact Resistance
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Solution Overview
Problem
Current technologies for forming epitaxial source/drain features in semiconductor devices face challenges with critical dimension uniformity and device performance due to varying growth rates on different surface orientations and gate spacings, leading to shape discrepancies in short and long channel regions, which affect contact resistance and transistor performance.
Innovation Solution
The formation of epitaxial source/drain features is controlled to have higher growth rates on (100) surface orientations compared to (110) and (111) orientations, resulting in bar-like shapes in short channel regions and diamond-like shapes in long channel regions, increasing the raise height and surface area for improved contact resistance and device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional epitaxial growth is used with uniform growth rates, then manufacturing process is simple, but critical dimension uniformity suffers due to varying surface orientations and gate spacings
Solution Approach 1:
The patent implements different growth rates for different crystallographic orientations by controlling epitaxial conditions. Specifically, the growth rate on (100) surfaces is made higher than on (110) and (111) surfaces, creating locally optimized shapes for different regions of the source/drain features depending on their surface orientation and gate spacing characteristics.
2Reliability
If higher growth rates are used to increase raise height, then contact resistance improves, but critical dimension uniformity deteriorates
Solution Approach 1:
The patent changes the growth rate parameters selectively based on crystallographic orientation. By adjusting epitaxial growth conditions to favor (100) surface growth over (110) and (111) surfaces, the method achieves higher raise heights and improved contact resistance while maintaining critical dimension uniformity through orientation-dependent growth control.
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 enhances the raise height of epitaxial source/drain features in long channel regions, reducing contact resistance and improving transistor performance without compromising critical dimension uniformity in short channel regions.
Implementation Method 1
The formation of epitaxial source/drain features is controlled to have higher growth rates on (100) surface orientations compared to (110) and (111) orientations
Data Source
AI summary
Semiconductor device includes a substrate having multiple fins formed from a substrate, a first source/drain feature comprising a first epitaxial layer in contact with a first fin, a second epitaxial layer formed on the first epitaxial layer, and a third epitaxial layer formed on the second epitaxial layer, the third epitaxial layer comprising a center portion and an edge portion that is at a different height than the center portion; a fourth epitaxial layer formed on the third epitaxial layer, a second source/drain feature adjacent the first source/drain feature, comprising a first epitaxial layer in contact with a second fin, a second epitaxial layer formed on the first epitaxial layer of the second source/drain feature, a third epitaxial layer formed on the second epitaxial layer of the second source/drain feature, the third epitaxial layer comprising a center portion and an edge portion that is at a different height than the center portion of the third epitaxial layer of the second source/drain feature; and a fourth epitaxial layer formed on the third epitaxial layer of the second source/drain feature.