Uniform Epitaxial Source/Drain Height via Sacrificial Spacers
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Solution Overview
Problem
Existing semiconductor devices face variability issues due to non-uniform heights of epitaxially grown source/drain regions, which affect device performance and reliability.
Innovation Solution
A method is developed to form semiconductor devices with uniformly heighted epitaxial source/drain regions by growing pillar portions on sacrificial spacers and selectively removing them, ensuring consistent heights across the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If epitaxial growth is used to form source/drain regions, then device current density and electrostatics are improved, but height non-uniformity increases device variability
Solution Approach 1:
Sacrificial spacers are introduced as intermediary structures during epitaxial growth. These spacers act as temporary mediators that define the growth boundaries and ensure uniform source/drain region heights. After the epitaxial growth completes with uniform dimensions, the sacrificial spacers are selectively removed, leaving behind precisely uniform source/drain regions without affecting the height consistency.
2Manufacturing precision
If selective removal of sacrificial spacers is performed, then source/drain height uniformity is achieved, but process complexity increases
Solution Approach 1:
The sacrificial spacers are formed in advance before the epitaxial growth of source/drain regions. This preliminary action establishes precise geometric boundaries that control the eventual source/drain region dimensions. By preparing the spacer structures beforehand, the subsequent epitaxial growth process automatically produces uniform heights, and the final spacer removal is a straightforward selective etching step rather than a complex process.
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 ensures that the epitaxial source/drain regions have the same or substantially the same height, reducing device variability and improving manufacturing consistency and performance.
Implementation Method 1
a plurality of source/drain regions are grown from the plurality of second semiconductor layers. The plurality of source/drain regions are adjacent the plurality of patterned stacks and include a plurality of pillar portions formed on lateral sides of the plurality of sacrificial spacers
Data Source
AI summary
A method for manufacturing a semiconductor device includes forming a plurality of semiconductor layers on a semiconductor substrate, and forming a plurality of gate structures spaced apart from each other on the semiconductor layers. The semiconductor layers are patterned into a plurality of patterned stacks spaced apart from each other, wherein the plurality of patterned stacks are under the plurality of gate structures. The method also includes forming a plurality of sacrificial spacers on lateral sides of the plurality of gate structures, and growing a plurality of source/drain regions. The source/drain regions are adjacent the patterned stacks and include a plurality of pillar portions formed on lateral sides of the sacrificial spacers. The sacrificial spacers and the plurality of pillar portions are removed.