Silicon Carbide PN Junction Protection Against Blue Light Resin Degradation
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Solution Overview
Problem
Conventional silicon carbide semiconductor devices experience degradation of sealing resin due to blue light generated by pn junctions, leading to adhesion issues and reliability concerns, as the protective films used are translucent and allow light to reach the resin.
Innovation Solution
An opaque protective film, such as an organic black polyimide film or inorganic polysilicon film, is applied in the outer peripheral and edge termination regions to block the blue light generated by pn junctions, preventing it from reaching the sealing resin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an opaque protective film is added to block blue light, then reliability is improved, but device complexity increases
Solution Approach 1:
The protective film structure is segmented into multiple layers with different functions: an interlayer insulating film layer and an opaque protective film layer. This segmentation allows each layer to perform its specific function independently while collectively solving the problem of light-induced degradation.
Solution Approach 2:
The opaque protective film acts as an intermediary element between the pn junction and the sealing resin, blocking the harmful blue light from reaching the resin and causing degradation, thereby protecting the sealing resin without affecting the electrical functionality of the device.
2Reliability
If the protective film covers the entire front surface, then reliability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The opaque protective film is selectively applied only to the outer peripheral portion of the active region where the pn junction is located, rather than covering the entire front surface. This local application approach blocks light where it is most harmful while reducing manufacturing complexity and material usage.
3Ease of manufacture
If a transparent protective film is used, then ease of manufacture is improved, but object-generated harmful factors increase
Solution Approach 1:
The protective film is designed with opaque characteristics, specifically black in color, to absorb and block blue light wavelengths. This color property prevents the transmission of harmful blue light from the pn junction to the sealing resin, solving the light-induced degradation problem.
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 opaque protective film effectively suppresses resin degradation, enhances adhesion between the resin and the film, and improves the reliability of the semiconductor device by blocking blue light, thus maintaining film quality and reducing leakage current and on-voltage variations.
Implementation Method 1
a first protective film selectively provided on the first main surface... The first protective film blocks light generated by the second forward current that passes through the second pn junction
Data Source
AI summary
A silicon carbide semiconductor device has a first semiconductor region of a first conductivity type, provided in a semiconductor substrate, spanning an active region and a termination region. A second semiconductor region of a second conductivity type is provided between a first main surface and the first semiconductor region, in the active region. A device structure having a first pn junction is provided between the first and second semiconductor regions. An outer peripheral portion of the active region is provided between the first main surface and the first semiconductor region in the active region, and constitutes a second-conductivity-type outer peripheral region that surrounds a periphery of the device structure and forms a second pn junction with the first semiconductor region. A first protective film is provided on the first main surface. The first protective film blocks light generated by a forward current passing through the first and second pn junctions.