Multi-Layer Doping Wafer Structure for Power Device Resistance Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional semiconductor wafer structures for power devices, such as VDMOS transistors, face challenges in minimizing conduction resistance while maintaining high breakdown voltage, particularly due to high JFET resistance which is difficult to optimize.
Innovation Solution
A wafer structure is designed with multiple doping layers of varying concentrations, where a high doping concentration first layer is followed by a lower concentration second layer and then a higher concentration third layer, reducing JFET resistance and conduction resistance without compromising breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional single-layer doping structure is used, then the breakdown voltage can be maintained, but the conduction resistance and JFET resistance remain high
Solution Approach 1:
The doping structure is segmented into three distinct layers with different doping concentrations. The first layer has high doping concentration, the second layer has lower doping concentration, and the third layer has intermediate doping concentration. This segmentation allows each layer to contribute differently to the overall device performance, with the lower-doped second layer maintaining breakdown voltage and the higher-doped first and third layers reducing conduction resistance.
Solution Approach 2:
Different regions of the wafer structure are given different doping qualities tailored to their specific functions. The first doping layer near the substrate provides high carrier concentration for low conduction resistance, the second doping layer provides low doping for high breakdown voltage, and the third doping layer provides intermediate doping to balance both requirements. This local quality differentiation resolves the contradiction between conduction resistance and breakdown voltage.
2Object-affected harmful factors
If the doping concentration is increased to reduce conduction resistance, then the conduction resistance decreases, but the breakdown voltage is compromised
Solution Approach 1:
The doping structure is divided into three segments with progressively different concentrations. The first layer has high doping concentration to reduce conduction resistance, while the second layer has low doping concentration to maintain breakdown voltage. The third layer provides an intermediate concentration to balance both requirements, allowing the device to achieve low conduction resistance without sacrificing breakdown voltage.
Solution Approach 2:
The doping concentration parameter is changed across different layers rather than being uniform. By varying the doping concentration from high in the first layer to low in the second layer and intermediate in the third layer, the patent optimizes both conduction resistance and breakdown voltage simultaneously, resolving the contradiction between these two parameters.
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 structure effectively reduces conduction resistance and saturation voltage drop in power devices like VDMOS transistors, improving their performance in switching voltage regulators.
Implementation Method 1
A wafer structure configured for a power device can include: (i) a first doping layer having a high doping concentration; (ii) a second doping layer on the first doping layer, where a doping concentration of the second doping layer is less than the high doping concentration; and (iii) a third doping layer on the second doping layer, where a doping concentration of the third doping layer is greater than the doping concentration of the second doping layer
Data Source
AI summary
In one embodiment, a wafer structure configured for a power device can include: (i) a first doping layer having a high doping concentration; (ii) a second doping layer on the first doping layer, where a doping concentration of the second doping layer is less than the high doping concentration; and (iii) a third doping layer on the second doping layer, where a doping concentration of the third doping layer is greater than the doping concentration of the second doping layer. For example, the power device can be part of a switching voltage regulator.