LDMOS Shield Wiring for Leakage Current Reduction
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Solution Overview
Problem
High voltage applications in LDMOS transistors lead to increased leakage current due to wiring placement above the transistor, which affects the reliability and efficiency of integrated circuits used in applications like vehicle control systems.
Innovation Solution
Incorporating a first shield wiring that encloses a portion of the source region not covered by the gate electrode, connected to a semiconductor region with a higher impurity concentration, to shield the electric field and prevent current paths from forming between the source and drain regions, thereby reducing leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high voltage is applied between source and drain in LDMOS transistor, then the transistor can operate in high voltage applications, but leakage current increases due to electric field effects
Solution Approach 1:
A shield wiring is introduced as an intermediary element between the source region and the wiring above the transistor. This shield wiring, connected to a semiconductor region with higher impurity concentration, acts as a mediator to block the electric field lines from directly connecting the source and drain regions, thereby reducing leakage current while maintaining high voltage operation capability
Solution Approach 2:
The transistor structure is segmented by introducing a shield wiring that divides the electric field path. The shield wiring encloses a portion of the source region not covered by the gate electrode, creating separate field regions and preventing direct electric field coupling between source and drain, thus reducing leakage current
2Ease of manufacture
If wiring is placed above the transistor for high voltage applications, then the circuit can be completed, but leakage current paths form between source and drain regions
Solution Approach 1:
The shield wiring serves as an intermediary barrier between the source region and the overlying wiring structure. By connecting the shield wiring to a higher impurity concentration region, it effectively blocks current paths that would otherwise form through the electric field, maintaining both circuit functionality and reliability
Solution Approach 2:
The shield wiring is positioned and configured in advance to prevent the formation of leakage current paths. By enclosing the uncovered portion of the source region before the harmful electric field effects can occur, it proactively counteracts the potential leakage current issue
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
The implementation effectively suppresses leakage current, maintaining the integrity of the gate insulating film and reducing current flow to less than 1 μA in the non-conductive state, enhancing the reliability and efficiency of high voltage applications.
Implementation Method 1
a first shield wiring that encloses a portion of the source region in a plan view in conjunction with the gate electrode, the portion being not covered by the gate electrode, and is connected to the first semiconductor region
Data Source
AI summary
A semiconductor device including a gate insulating film; a gate electrode; a source region of a first conductivity; a drain region of the first conductivity type; a drift region of the first conductivity type formed between the channel region and the drain region; a first semiconductor region of a second conductivity type that encloses the source region, the drift region and the drain region, and includes the channel region; and a first shield wiring that encloses a portion of the source region in a plan view in conjunction with the gate electrode, the portion being not covered by the gate electrode, and is connected to the first semiconductor region, or that covers the portion and is connected to the first semiconductor region and the source region.