Trench Semiconductor Source Layout for Lower Turn-On Loss
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Solution Overview
Problem
Semiconductor trench devices face challenges in improving switching characteristics due to parasitic capacitances, leading to undesired turn-on losses during switching between on- and off-states.
Innovation Solution
The semiconductor device incorporates a plurality of trenches with a gate electrode, a source electrode subdivided into parts with varying conductance per unit length, and an auxiliary electrode, along with resistive coupling between the source electrode and the source contact area, to reduce parasitic capacitances and turn-on losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If parasitic capacitances are present in semiconductor trench devices, then the device structure is simple and easy to manufacture, but turn-on losses increase and switching characteristics deteriorate
Solution Approach 1:
The source electrode is divided into multiple segments (first source electrode portion, second source electrode portion, third source electrode portion) with different conductances. This segmentation allows each portion to have optimized electrical characteristics, reducing overall parasitic capacitance while maintaining current conduction capability. The segmented structure directly addresses the contradiction by reducing turn-on losses through strategic placement and varying conductances of different source electrode segments.
Solution Approach 2:
Different portions of the source electrode are assigned different conductance values (first portion has higher conductance, second portion has lower conductance). This local quality variation optimizes the electrical performance at different locations within the device, allowing reduction of parasitic capacitance effects in critical areas while maintaining overall device functionality and reducing turn-on losses.
2Loss of energy
If source electrode is subdivided into parts with varying conductance, then parasitic capacitances are reduced, but manufacturing complexity increases
Solution Approach 1:
The conductance of different source electrode portions is varied by changing geometric parameters (width, length, thickness) or material properties of each segment. This parameter variation achieves reduced parasitic capacitance while using standard semiconductor fabrication techniques, balancing performance improvement with manufacturing feasibility.
3Reliability
If auxiliary electrode is added to provide resistive coupling, then switching characteristics are improved, but device complexity and manufacturing steps increase
Solution Approach 1:
An auxiliary electrode is introduced as an intermediary element that provides resistive coupling between the source contact area and the source electrode. This intermediate structure enables controlled electrical connection that reduces parasitic capacitance effects and improves switching characteristics, while the resistive coupling mechanism directly addresses the reliability improvement goal.
Solution Approach 2:
The auxiliary electrode is positioned in a separate trench from the main gate and source electrodes, effectively extracting the coupling function into a dedicated structure. This separation allows independent optimization of the auxiliary electrode's resistive coupling properties without interfering with the primary electrode functions, improving switching characteristics while managing device complexity.
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 suppresses turn-on voltage tails, reducing turn-on losses and enhancing switching characteristics by introducing a resistive coupling that mitigates the shielding effect of the trenches.
Implementation Method 1
The source wiring line and the auxiliary electrode are electrically connected in series between the source contact area and the source electrode
Implementation Method 2
parasitic capacitances have an impact on the overall switching behavior of the device
Implementation Method 3
A conductance per unit length of the first part along a longitudinal direction of the source electrode is smaller than a conductance per unit length of the second part
Data Source
AI summary
A semiconductor device is proposed. The semiconductor device includes a plurality of trenches extending into in a semiconductor body from a first main surface. A first group of the plurality of trenches includes a gate electrode. A second group of the plurality of trenches includes a source electrode. A third group of the plurality of trenches includes an auxiliary electrode. The source electrode is electrically coupled to a source contact area via a source wiring line and the auxiliary electrode. The source wiring line and the auxiliary electrode are electrically connected in series between the source contact area and the source electrode.