Semiconductor Trench Barrier Layer Punch Through Control
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Solution Overview
Problem
Semiconductor devices face challenges in preventing punch through and leakage current due to depletion layers reaching trench surfaces, especially in trench and source trench configurations, where the depletion layer spreading from pn junctions can contact electrodes, leading to electrical conductivity issues.
Innovation Solution
The semiconductor device incorporates a barrier-forming layer with a potential barrier higher than the potential barrier between the second conductivity type layer and the second electrode, disposed between the trench or source trench side surfaces and electrodes, and optionally on the trench or source trench edge portions, to restrain punch through by creating a potential barrier that prevents the depletion layer from reaching the electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the trench structure is used to improve device integration, then device complexity is reduced, but leakage current increases due to depletion layer reaching the trench side surface
Solution Approach 1:
A barrier-forming layer is introduced as an intermediary between the semiconductor layer and the electrode in the trench structure. This barrier-forming layer prevents the depletion layer from reaching the electrode, thereby blocking the harmful leakage current path while maintaining the integrated trench structure
Solution Approach 2:
The barrier-forming layer is selectively formed only at the trench side surface where the depletion layer spreads, rather than throughout the entire device. This localized approach prevents leakage current at the critical interface without unnecessarily complicating the overall device structure
2Reliability
If the depletion layer is allowed to spread naturally to improve carrier collection, then electrical conductivity is improved, but punch through occurs when the depletion layer reaches the trench side surface and contacts the electrode
Solution Approach 1:
The barrier-forming layer serves as a mediator that allows the depletion layer to spread for carrier collection while preventing it from reaching the electrode. The layer creates a potential barrier that stops the depletion layer's expansion at the critical interface, avoiding punch through
Solution Approach 2:
The barrier-forming layer is positioned in advance at the trench side surface to prevent the harmful effect of punch through before it can occur. By creating the potential barrier beforehand, the design preemptively blocks the depletion layer from contacting the electrode
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 configuration effectively restrains punch through and leakage current by creating a potential barrier that prevents the depletion layer from reaching the electrodes, even when the depletion layer spreads towards the trench or source trench surfaces, thereby enhancing electrical conductivity and device reliability.
Implementation Method 1
a barrier-forming layer that is disposed between the side surface of the trench and the second electrode and that forms a potential barrier between the barrier-forming layer and the second conductivity type layer higher than a potential barrier between the second conductivity type layer and the second electrode
Data Source
AI summary
The semiconductor device includes: a semiconductor layer in which a trench is formed having a side surface and a bottom surface; a second conductivity-type layer formed on the semiconductor layer on the side surface and the bottom surface of the trench; a first conductivity-type layer formed on the semiconductor layer so as to contact the second conductivity-type layer; a first electrode electrically connected to the first conductivity-type layer; a second electrode embedded in the trench and electrically connected to the second conductivity-type layer; and a barrier-forming layer which is arranged between the second electrode and the side surface of the trench and which, between said barrier-forming layer and the second conductivity-type layer, forms a potential barrier higher than the potential barrier between the second conductivity-type layer and the second electrode.