LDMOS Gate Oxide Thickness Variation for Rdson Reduction
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Solution Overview
Problem
Conventional LDMOS devices with thick oxide between the gate and drain exhibit higher resistance in lower voltage applications due to increased conduction path resistance, which hampers their performance.
Innovation Solution
The implementation of a gate structure with an oxidation extending from the gate to the drain region, comprising alternating thinner and thicker oxide portions, optimizes the oxide thickness for both low and high voltage applications, allowing for improved on-state performance without degrading off-state performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thick oxide is used between gate and drain to prevent gate to drain breakdown, then reliability is improved for higher voltage devices, but conduction path resistance increases for lower voltage devices
Solution Approach 1:
The patent applies local quality by implementing varying oxide thickness at different locations between the gate and drain. Specifically, the oxide layer is thinner near the gate region and thicker near the drain region, allowing the structure to simultaneously achieve low conduction resistance near the gate and high breakdown voltage capability near the drain. This spatial variation in oxide thickness resolves the contradiction between reliability and conduction performance.
2Reliability
If thick oxide is used to ensure high blocking voltage, then device reliability is improved, but on-state resistance increases
Solution Approach 1:
The patent implements local quality by creating a non-uniform oxide thickness profile where the oxide is thinner in regions requiring low resistance (near the gate) and thicker in regions requiring high breakdown voltage (near the drain). This localized differentiation allows the device to achieve both low on-state resistance and high blocking voltage capability simultaneously.
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 results in higher current and lower on-state resistance (Rdson) for LDMOS devices, enabling better performance in lower voltage applications while maintaining off-state performance, and allows for a smaller pitch design.
Implementation Method 1
an oxidation extending from the gate structure to the drain region in the drift region, the oxidation comprising alternating thinner and thicker portions
Data Source
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to a laterally diffused MOSFET (LDMOS) and methods of manufacture. The structure includes: a gate structure having a drain region and a source region; and an oxidation extending from the gate structure to the drain region of the gate structure, the oxidation comprising a thinner oxide portion and a thicker oxide portion.