Dummy Trench Gate Withstand Voltage Testing in IGBTs
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Solution Overview
Problem
Conventional methods for testing the withstand voltage of a dummy trench gate in insulated gate bipolar transistors (IGBTs) are inaccurate due to the gate electrode being connected to the emitter electrode during manufacturing, preventing post-formulation voltage testing and differing electrical field distributions during upper layer formation.
Innovation Solution
A semiconductor device and manufacturing method that include a dummy trench gate with separate wiring and a pad for applying a predetermined voltage, allowing for accurate withstand voltage testing by connecting the dummy pad and first electrode electrically through a conductive member before the upper layer is completed, enabling voltage application between the dummy pad and first electrode from outside the semiconductor substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the gate electrode is connected to the emitter electrode during manufacturing, then the manufacturing process is simplified, but the withstand voltage testing of the dummy trench gate cannot be performed accurately after upper layer formation
Solution Approach 1:
The gate electrode system is segmented into two independent parts: a first gate electrode connected to the emitter electrode for normal operation, and a second gate electrode connected to the collector electrode for withstand voltage testing. This segmentation allows independent control of testing and operation functions, enabling accurate measurement without compromising manufacturing simplicity.
Solution Approach 2:
A third electrode is introduced as an intermediary element that can be selectively connected to either the emitter electrode or the collector electrode. This intermediary enables flexible configuration where the same physical structure serves dual purposes: normal operation mode and withstand voltage testing mode, resolving the contradiction between manufacturing simplicity and measurement accuracy.
2Ease of manufacture
If the dummy trench gate is fixed to have the same potential as the emitter potential, then the manufacturing process is simplified, but the electrical field distribution during upper layer formation does not match the actual operating conditions
Solution Approach 1:
The electrical connection configuration is made dynamic rather than fixed. The third electrode can be selectively connected to different potentials (emitter or collector) depending on the operational phase. During upper layer formation, the third electrode is connected to the collector electrode to create accurate electrical field distribution, while during normal operation it connects to the emitter electrode for simplified manufacturing.
3Device complexity
If the gate electrode and emitter electrode are connected during manufacturing, then the device structure is simplified, but post-formulation voltage testing cannot be operated
Solution Approach 1:
The third electrode is pre-configured during manufacturing to be connectable to both the emitter electrode and collector electrode, but the actual connection to the collector electrode is established preliminarily only when needed for withstand voltage testing. This preliminary action capability is built into the structure without permanently increasing complexity, allowing testing to be operated when required.
Data Source
AI summary
A semiconductor device provides an element arrangement region on a semiconductor substrate including: a first semiconductor region on the semiconductor substrate; a second semiconductor region on the first semiconductor region; multiple trench gates penetrating the first semiconductor region and reaching the second semiconductor region; a third semiconductor region contacting the trench gate; a fourth semiconductor region on a rear surface; a first electrode connected to the first and second semiconductor regions; and a second electrode connected to the fourth semiconductor region. Each trench gate includes a main trench gate for generating a channel and a dummy trench gate for improving a withstand voltage of a component. The device further includes: a dummy gate wiring for applying a predetermined voltage to the dummy trench gate; and a dummy pad connected to the dummy gate wiring. The dummy pad and the first electrode are connected by a conductive member.