MOSFET Source Region Segmentation for Short-Circuit Tolerance
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Solution Overview
Problem
Existing semiconductor devices with parallel-connected high-resistance and low-resistance emitter layers do not generate sufficient voltage drop across the channel region, leading to inadequate short-circuit tolerance and higher contact resistance.
Innovation Solution
A semiconductor device structure with a source region comprising a source contact region, a source extension region, and a source resistance control region, where the source resistance control region is connected in series between the channel region and the source electrode, allowing for adjustable voltage drop and maintaining low contact resistance between the source electrode and the source region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the emitter layer includes parallel-connected high-resistance region and low-resistance region, then the contact resistance between emitter electrode and emitter layer is reduced, but the voltage drop across channel region and emitter electrode is insufficient
Solution Approach 1:
The emitter layer is segmented into three distinct regions: source contact region, source extension region, and source resistance control region. This segmentation allows each region to have optimized impurity concentrations for its specific function, enabling the source resistance control region to provide sufficient voltage drop while source contact region maintains low contact resistance.
Solution Approach 2:
Different regions of the emitter layer are assigned different impurity concentrations tailored to their local functions. The source contact region has high impurity concentration for low contact resistance, the source resistance control region has low impurity concentration for high voltage drop, and the source extension region has intermediate concentration. This local quality differentiation resolves the contradiction between contact resistance and voltage drop.
2Power
If the emitter layer includes parallel-connected high-resistance region and low-resistance region, then low ON voltage is achieved, but saturation current reduction effect is insufficient
Solution Approach 1:
The emitter layer is divided into functional segments where source contact region and source extension region provide low resistance paths for ON current (maintaining low ON voltage), while source resistance control region provides high resistance to limit saturation current during short-circuit events. This segmentation enables simultaneous optimization of both ON voltage and short-circuit tolerance.
Solution Approach 2:
Different impurity concentration levels are applied locally to different emitter regions. High impurity concentration in source contact region ensures low contact resistance for power efficiency, while low impurity concentration in source resistance control region creates sufficient voltage drop to reduce saturation current, thereby improving short-circuit tolerance without sacrificing ON voltage performance.
3Ease of manufacture
If the source region has uniform impurity concentration, then manufacturing process is simplified, but voltage drop control and contact resistance optimization cannot be achieved simultaneously
Solution Approach 1:
The source region is segmented into three zones with different impurity concentrations. This can be achieved through selective ion implantation or epitaxial growth processes. The segmentation enables independent optimization of voltage drop and contact resistance without requiring complete redesign of the manufacturing process, as each region can be formed using standard semiconductor fabrication techniques.
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 semiconductor device enhances short-circuit tolerance by reducing saturation current and maintaining low contact resistance, effectively preventing element breakdown during short-circuit events.
Implementation Method 1
the resistance value of the entire emitter layer is substantially determined by the resistance value of the low-resistance region. This does not generate large voltage drop across the channel region and the emitter electrode
Implementation Method 2
a gate electrode arranged over the drift layer while a gate insulating film is arranged between the drift layer and the gate electrode
Data Source
AI summary
A source region of a MOSFET includes: a source contact region connected to a source pad; a source extension region adjacent to a channel region in a well region; and a source resistance control region arranged between the source extension region and the source contact region. The source resistance control region is different in an impurity concentration from the source extension region and the source contact region. These three regions are connected in series between the source pad and the channel region in the well region.