LDMOS FinFET Subfin Dimension Segmentation for HCI Reliability
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Solution Overview
Problem
LDMOS FinFET devices face challenges with hot carrier injection (HCI) due to charge carriers becoming trapped in subfin portions, leading to increased current and altered operational characteristics, which current approaches fail to fully address effectively.
Innovation Solution
An integrated circuit structure featuring a semiconductor fin with subfin portions of different lateral dimensions, where the second subfin portion within the drain extension region has a smaller lateral dimension, reducing subfin current and improving HCI reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If subfin portions are used in LDMOS FinFET devices, then device performance is improved, but hot carrier injection reliability deteriorates due to charge carriers becoming trapped in subfin portions
Solution Approach 1:
The fin structure is segmented into multiple subfin portions with different lateral dimensions. The first subfin portion has a first lateral dimension while the second subfin portion has a second lateral dimension that is smaller than the first. This segmentation allows different regions of the fin to have optimized characteristics for their specific functions, reducing hot carrier injection in the drain extension region while maintaining performance in other regions.
Solution Approach 2:
Different portions of the fin structure are given different lateral dimensions tailored to their specific functional requirements. The second subfin portion, located in the drain extension region, has a smaller lateral dimension specifically to reduce hot carrier injection in that critical area, while other portions maintain larger dimensions for optimal current flow and device performance.
2Reliability
If implants or local trench isolations are used to reduce subfin current, then hot carrier injection reliability improves, but device complexity and manufacturing difficulty increase
Solution Approach 1:
Instead of adding complex structural elements like implants or local trench isolations, the invention changes the geometric parameter of the fin structure itself. By varying the lateral dimension of different subfin portions, the patent achieves hot carrier injection reduction through a simple dimensional parameter change that is easier to manufacture and integrates more smoothly with standard fabrication processes.
3Object-generated harmful factors
If the second subfin portion has a smaller lateral dimension, then subfin current and impact ionization rate are reduced, but manufacturing precision requirements increase
Solution Approach 1:
The fin is divided into discrete subfin portions that can be formed using standard segmentation techniques in semiconductor fabrication. Each subfin portion can be defined by separate photolithography and etching steps, allowing precise control of lateral dimensions through conventional manufacturing processes while achieving the desired reduction in impact ionization rate.
Data Source
AI summary
An integrated circuit (IC) structure includes a semiconductor fin having a first longitudinal extent and a second longitudinal extent. The semiconductor fin has an upper fin portion having a uniform lateral dimension in the first longitudinal extent and the second longitudinal extent, a first subfin portion under the upper fin portion in the first longitudinal extent having a first lateral dimension, and a second subfin portion under the upper fin portion in the second longitudinal extent having a second lateral dimension different than the first lateral dimension. The second subfin may be used in a drain extension region of a laterally-diffused metal-oxide semiconductor (LDMOS) device. The second subfin reduces subfin current and improves HCI reliability, regardless of the type of LDMOS device.