MOSFET Blocking Structure to Prevent Joining Material Short-Circuits
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Solution Overview
Problem
In metal oxide semiconductor field effect transistors (MOSFETs), the potential difference between the source electrode and the drift electrode can cause the joining material to flow towards the source electrode or source wiring layer, potentially leading to short-circuiting due to contact between these components.
Innovation Solution
A blocking portion is provided on the semiconductor layer, electrically insulated from the source wiring layer and drain electrode, to prevent the joining material from contacting the source wiring layer, thereby blocking the potential short-circuiting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drift electrode is joined to the die pad via conductive joining material, then electrical connection is achieved, but the joining material may flow toward the source electrode causing short-circuiting
Solution Approach 1:
An insulating film is introduced as an intermediary layer between the source wiring layer and the potential path of joining material flow. This insulating film acts as a mediator that allows the joining material to be present in the region without causing direct contact between conductive elements, thus preventing short-circuiting while maintaining the electrical connection function.
Solution Approach 2:
The insulating film is applied in advance to the source wiring layer before the joining process. This preliminary protective action creates a barrier that prevents the joining material from causing harmful effects, addressing the potential short-circuit problem before it can occur during operation.
2Ease of manufacture
If the joining material is allowed to flow freely, then joining process is simplified, but contact with source electrode may occur causing short-circuiting
Solution Approach 1:
The insulating film serves as a mediator that enables the joining material to flow freely during the joining process without compromising electrical insulation. This allows the joining process to remain simple while the insulating film prevents the harmful effect of direct contact between joining material and source electrode.
Solution Approach 2:
The structure is segmented into distinct functional layers: the source wiring layer, the insulating film layer, and the joining material region. This segmentation allows each layer to perform its specific function independently, with the insulating film layer specifically dedicated to preventing short-circuits while allowing manufacturing simplicity.
Data Source
AI summary
A semiconductor device according to an embodiment includes: a semiconductor layer including a first principal surface, and a second principal surface on the opposite side from the first principal surface; a first conductive portion provided on the first principal surface of the semiconductor layer; a second conductive portion that is provided on the second principal surface of the semiconductor layer, and is joined to a metal piece via a joining material having conductivity, the joining material not being in contact with the first conductive portion; and a blocking portion that is provided on the first principal surface on the outer side of the first conductive portion, and is electrically insulated from the first conductive portion and the second conductive portion.