Trench Schottky Diode Guard Ring Stress Relief
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Solution Overview
Problem
Trench Schottky diodes face issues with high reverse leakage current, low reverse voltage tolerance, and stress-induced damage during manufacturing, leading to potential malfunction due to cracks caused by unrelieved trench-etching stress.
Innovation Solution
A method involving the formation of trenches in a semiconductor substrate, followed by the creation of a gate oxide layer and polysilicon structure within these trenches, with a guard ring and electrode configuration to block leakage current and enhance adhesion, using a borophosphosilicate glass layer and specific metal layers to improve reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If trenches are formed in the semiconductor substrate to reduce reverse leakage current, then reverse leakage current is reduced, but stress-induced cracks and device damage occur during reliability testing
Solution Approach 1:
The device structure is divided into a device area and a guard area, with the guard ring forming a separate protective structure that isolates stress-prone regions from the active Schottky junction, preventing stress-induced cracks while maintaining the trench's leakage-reduction function
Solution Approach 2:
The guard ring is formed before the final Schottky junction metallization, preemptively providing stress relief and structural support to the trench regions before they are subjected to subsequent processing stresses and reliability testing
2Reliability
If a guard ring is formed to cover portions of the semiconductor substrate, gate oxide layer and polysilicon structure, then device reliability is improved by preventing stress-induced cracks, but device area is reduced
Solution Approach 1:
The guard ring is strategically positioned only in regions where stress relief is needed (around the trench periphery), while leaving the central active device area untouched, thus providing localized protection without unnecessarily reducing the overall device functional area
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 approach results in a trench Schottky diode with lower reverse leakage current, lower forward voltage drop, higher reverse voltage tolerance, and reduced reverse recovery time, enhancing the device's reliability and performance compared to conventional Schottky diodes.
Implementation Method 1
the gate oxide layer and the polysilicon structure are formed in the trenches. Both the gate oxide layer and the polysilicon structure protrude above a surface of the semiconductor substrate
Implementation Method 2
a Schottky barrier contact is formed on the interface between the semiconductor mesas and the anode metal layer
Implementation Method 3
using a borophosphosilicate glass layer and specific metal layers to improve reliability
Implementation Method 4
an electrode is formed over the guard area and the device area
Data Source
AI summary
A trench Schottky diode and its manufacturing method are provided. The trench Schottky diode includes a semiconductor substrate having therein a plurality of trenches, a gate oxide layer, a polysilicon structure, a guard ring and an electrode. At first, the trenches are formed in the semiconductor substrate by an etching step. Then, the gate oxide layer and the polysilicon structure are formed in the trenches and protrude above a surface of the semiconductor substrate. The guard ring is formed to cover a portion of the resultant structure. At last, the electrode is formed above the guard ring and the other portion not covered by the guard ring. The protruding gate oxide layer and the protruding polysilicon structure can avoid cracks occurring in the trench structure.