Laterally Recessed Source/Drain Epitaxial Region for Isolation
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Solution Overview
Problem
As integrated circuits scale down, it becomes challenging to form large source/drain epitaxial regions without merging them with adjacent regions, which affects device performance due to limited space and precise sizing requirements.
Innovation Solution
A method involving the formation of a laterally recessed source/drain epitaxial region by removing a lateral end portion of a spacer to expose and recess the epitaxial region, allowing for the growth of larger source/drain epitaxial regions on adjacent devices without merging, using a liner and spacer configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the source/drain epitaxial region is made larger to improve device performance, then device performance is improved, but the source/drain epitaxial regions merge with adjacent regions due to limited space
Solution Approach 1:
A spacer is formed around the source/drain epitaxial region before the epitaxial growth is complete. This spacer acts as a pre-established barrier that defines the maximum lateral extent of the epitaxial region, preventing merging with adjacent regions while allowing the region to grow to its full beneficial size within the constrained space.
Solution Approach 2:
The spacer serves as an intermediary structure between the source/drain epitaxial region and adjacent regions. It provides a physical barrier that mediates the spatial relationship, enabling larger epitaxial regions to be formed without direct contact and merging with neighboring structures.
2Reliability
If the source/drain epitaxial region is made larger to improve device performance, then device performance is improved, but the lateral space required increases causing merging with adjacent regions
Solution Approach 1:
The spacer is formed in advance around the source/drain epitaxial region, establishing a predetermined lateral boundary before the epitaxial growth completes. This allows the epitaxial region to achieve its optimal size for performance while the spacer ensures it does not encroach into adjacent regions' space.
Solution Approach 2:
The spacer provides localized lateral confinement specifically at the boundaries of the source/drain epitaxial region, while allowing the region to expand freely in the vertical direction and within the confined lateral space. This localized control enables optimized epitaxial region dimensions without requiring additional overall lateral space.
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 enables the growth of larger source/drain epitaxial regions, improving device performance by maintaining structural and electrical isolation, and increasing the width of these regions beyond conventional limits, such as up to 70 nm in 14 nm devices.
Implementation Method 1
forming a spacer surrounding the first source/drain epitaxial region
Implementation Method 2
forming a liner over the spacer and in contact with the laterally recessed first source/drain epitaxial region
Implementation Method 3
removing a lateral end portion of the spacer from over the first source/drain epitaxial region to expose a lateral end portion of the first source/drain epitaxial region
Data Source
AI summary
The disclosure is directed to an integrated circuit structure. The integrated circuit structure may include: a first device region laterally adjacent to a second device region over a substrate, the first device region including a first fin and the second device region including a second fin; a first source/drain epitaxial region substantially surrounding at least a portion of the first fin; a spacer substantially surrounding the first source/drain epitaxial region, the spacer including an opening in a lateral end portion of the spacer such that the lateral end portion of the spacer overhangs a lateral end portion of the first source/drain epitaxial region; and a liner conformally coating the lateral end portion of the first source/drain epitaxial region beneath the overhanging lateral end portion of the spacer, wherein the liner includes an electrical insulator.