Power FET Island Fuse Layout for Fast Defect Isolation
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Solution Overview
Problem
Existing methods for manufacturing power transistors with large dimensions, such as connecting multiple elementary transistors in parallel, face issues like short-circuits during production, which require time-consuming island testing and insulation, and leakage currents persist even after fuse breakage due to low breakdown voltage between electrodes.
Innovation Solution
A field effect transistor design featuring a substrate with a semiconductor structure, island-based electrodes, connection tracks, and fuse areas that can be broken to isolate defective islands, with a passivation layer covering the broken fuses to prevent leakage, allowing for simultaneous insulation of defective islands during manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If fuse areas are broken to electrically insulate defective islands, then manufacturing time is reduced, but leakage currents may still circulate in defective drain fingers
Solution Approach 1:
A polymer material layer is introduced as an intermediary substance between the broken fuse areas and the external environment. This layer fills the spaces created by broken fuses and provides additional electrical insulation, preventing leakage currents while allowing the fast fuse-breaking method to be used.
Solution Approach 2:
The polymer material is deposited in advance to cover and insulate the fuse areas before any breakage occurs. This preparatory insulation layer ensures that when fuses are broken to isolate defective islands, the broken areas are already protected against leakage currents.
2Power
If multiple elementary transistors are connected in parallel to create large-dimension power transistors, then current handling capability is improved, but the complexity of detecting and isolating defective islands increases
Solution Approach 1:
The fuse areas are designed to automatically indicate their functional state through their electrical properties. When a fuse area is broken, it creates a detectable change in the electrical characteristics of the corresponding island, allowing defective islands to be automatically identified without complex external testing equipment.
Solution Approach 2:
The fuse areas are extracted as separate, distinct elements between the connection tracks and the electrode portions. This separation allows each island to be independently controlled and isolated through its dedicated fuse area, simplifying the detection and isolation process for defective islands.
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 approach significantly reduces manufacturing time by enabling the electrical isolation of defective islands in a single step and minimizes leakage currents by ensuring the fuse areas can withstand maximum operating currents and breakage, enhancing the transistor's operational efficiency.
Implementation Method 1
a passivation layer arranged on the islands, the connection tracks and the fuse areas, the passivation layer occupying each space created by the breakage of said at least one second fuse area
Implementation Method 2
at least one second fuse area broken so as to electrically insulate an associated portion of the first electrode belonging to a defective island
Data Source
AI summary
A field effect transistor includes a substrate; a semiconductor structure formed on a main face of the substrate, the semiconductor structure including a channel area; a first electrode and a second electrode between which extends the channel area, the first electrode including a plurality of portions spaced apart from each other, each portion of the first electrode contributing to forming an elementary transistor referred to as island; connection tracks for electrically connecting the portions of the first electrode to one another; and in which each portion of the first electrode is connected to a connection track through a fuse area, each fuse area associated with the portion of the first electrode of an island being capable of being broken in such a way as to electrically insulate said island if it is defective.