Epitaxy Mask Layer for Strained Silicon Transistor Integrity
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Solution Overview
Problem
Conventional strained silicon transistor processes often damage the top gate structure or epitaxial layer during spacer removal, leading to deteriorated electrical performance.
Innovation Solution
A method where epitaxy and source/drain implantation processes are performed without removing disposable spacers, allowing independent control of source/drain position and width using a single epitaxy mask layer, thereby preventing damage to the strained silicon transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If disposable spacers are removed after epitaxial layer formation, then the spacers can be reused for defining epitaxy recess positions, but the top of gate structure or epitaxial layer is damaged, deteriorating electrical performance
Solution Approach 1:
The patent extracts the masking function from the disposable spacer and transfers it to a dedicated epitaxy mask layer. This mask layer is specifically designed to protect the gate structure and epitaxial layer during etching, while allowing spacer removal without damage. The masking function is separated from the spacer structure itself, enabling spacer reuse without compromising device integrity.
Solution Approach 2:
The epitaxy mask layer serves as an intermediary protective element between the etching process and the gate structure/epitaxial layer. This intermediate layer absorbs the mechanical stress of spacer removal and protects the underlying sensitive structures, allowing the spacer to be removed safely while maintaining electrical performance.
2Device complexity
If disposable spacers are used to define epitaxy recess positions, then the process is simple and straightforward, but the spacers must be removed which causes damage to the gate structure or epitaxial layer
Solution Approach 1:
The patent segments the masking function from the spacer structure by introducing a separate epitaxy mask layer. This segmentation allows the spacer to serve only its positioning function while the dedicated mask layer provides protection during critical operations. The separation of functions enables independent optimization of each component's performance.
Solution Approach 2:
The epitaxy mask layer is formed in advance before spacer removal, providing pre-established protection for the gate structure and epitaxial layer. This preliminary protective measure ensures that when spacers are removed, the sensitive structures are already shielded, preventing damage before it can occur.
3Ease of manufacture
If conventional spacer removal process is used, then the process flow is established and proven, but damage to the top of gate structure or epitaxial layer occurs, reducing device performance
Solution Approach 1:
The epitaxy mask layer provides beforehand cushioning protection for the gate structure and epitaxial layer during spacer removal. This protective layer absorbs mechanical stresses and prevents direct contact between removal tools and sensitive structures, cushioning against potential damage before it can affect device performance.
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 manufacturing process by maintaining the integrity of the gate structure and epitaxial layers, improving the electrical performance of semiconductor devices by avoiding spacer removal-related damage.
Implementation Method 1
forming first type epitaxial layers in the substrate at both sides of each gate structure in the first type semiconductor region
Implementation Method 2
a biaxial tensile strain is induced in the epitaxial silicon layer due to the silicon germanium, which has a larger lattice constant than silicon
Data Source
AI summary
A method of manufacturing a semiconductor device including the steps of providing a substrate having first type semiconductor regions and second type semiconductor regions, forming a conformal first epitaxy mask layer on the substrate, forming first type epitaxial layer in the substrate of the first type semiconductor regions, forming a conformal second epitaxy mask layer on the substrate, forming second type epitaxial layer in the substrate of the second type semiconductor regions, and removing the second epitaxy mask layer.