Variable Thickness Gate Dielectric for Power Transistors
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Solution Overview
Problem
Power transistors in automotive and industrial electronics require low on-state resistance (Ron) and high voltage blocking capability, while minimizing capacitances to reduce switching losses, which existing technologies struggle to achieve effectively.
Innovation Solution
The design of an integrated circuit with a transistor in a semiconductor substrate featuring a source region, drain region, channel region, drift zone, and gate electrode, where the gate electrode is adjacent to the channel region and gate dielectric has varying thicknesses, and a field plate is used to improve breakdown voltage characteristics and reduce on-resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional gate dielectric structure is used, then the manufacturing process is simple, but the on-resistance cannot be sufficiently reduced and voltage blocking capability is compromised
Solution Approach 1:
The gate dielectric structure employs different thickness regions: a first thickness in the channel region for optimal transistor switching, and a second greater thickness in the drift region for enhanced voltage blocking and reduced on-resistance. This local differentiation allows each region to be optimized for its specific function without compromising the other.
Solution Approach 2:
The gate dielectric is segmented into distinct thickness zones along the drift region, with the thickness increasing from the channel toward the drain. This segmentation enables independent optimization of electrical characteristics in different spatial zones, achieving both low on-resistance and high voltage blocking capability.
2Loss of energy
If capacitances are minimized to reduce switching losses, then switching speed improves, but voltage blocking capability may be compromised
Solution Approach 1:
The increased gate dielectric thickness is specifically positioned in the drift region where voltage blocking is critical, while maintaining thinner thickness near the channel to minimize capacitance. This local quality differentiation allows energy loss reduction in switching regions while preserving voltage blocking in the drift region.
Data Source
AI summary
A semiconductor device includes a transistor in a semiconductor substrate having a main surface. The transistor includes a source region, a drain region, a channel region, a drift zone, a gate electrode, and a gate dielectric adjacent to the gate electrode. The gate electrode is disposed adjacent to at least two sides of the channel region. The channel region and the drift zone are disposed along a first direction parallel to the main surface between the source region and the drain region. The gate dielectric has a thickness that varies at different positions of the gate electrode.