Floating Well Region Prevents Oxide Precipitation in Semiconductor Devices
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Solution Overview
Problem
In semiconductor devices, particularly under high humidity conditions, moisture can cause the semiconductor layer to react and precipitate oxides, leading to peeling of resin layers and potential defects due to the formation of leak paths through cavities created by this peeling.
Innovation Solution
The semiconductor device incorporates a floating well region with a floating potential, spaced apart from the termination well region, which extends beyond the outer peripheral end of the field insulating film to prevent the depletion layer from reaching the front surface, thereby reducing oxide precipitation and peeling of resin layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a termination well region is formed in the semiconductor layer to secure withstand voltage, then the electric field is reduced when reverse voltage is applied, but oxide precipitation occurs on the outer peripheral side of the field insulating film causing peeling of the resin layer
Solution Approach 1:
The invention divides the well region into two distinct segments: a termination well region (first conductivity type) formed to extend beyond the field insulating film for voltage withstanding, and a floating well region (second conductivity type) formed in the outer peripheral region to prevent oxide precipitation. This segmentation allows each region to perform its specific function independently, resolving the contradiction between voltage withstanding capability and oxide prevention.
Solution Approach 2:
The invention applies different conductivity types to different spatial regions: the termination well region uses the first conductivity type (same as semiconductor layer) for voltage blocking, while the floating well region uses the second conductivity type (opposite to semiconductor layer) for oxide prevention. This local differentiation of electrical properties enables simultaneous achievement of both withstand voltage and oxide precipitation prevention.
2Reliability
If the termination well region extends beyond the field insulating film, then voltage withstanding capability is improved, but the depletion layer reaches the front surface causing oxide precipitation and resin layer peeling
Solution Approach 1:
The well region is segmented into a termination well region that extends beyond the field insulating film for voltage withstanding, and a floating well region that prevents depletion layer extension to the front surface. This segmentation allows the depletion layer to be controlled within the floating well region rather than reaching the front surface, maintaining manufacturing precision while achieving voltage withstanding capability.
Solution Approach 2:
The floating well region acts as an intermediary structure between the termination well region and the front surface. It mediates the depletion layer behavior by providing a region where the depletion layer can terminate, preventing direct contact with the front surface and thus preventing oxide precipitation while maintaining the voltage withstanding function of the termination well region.
3Object-affected harmful factors
If a protective film is formed to protect the front surface, then the semiconductor device is protected, but moisture in the protective film causes oxide precipitation under high humidity conditions
Solution Approach 1:
The floating well region is formed in advance before the protective film is applied, creating a depletion layer barrier that prevents oxide precipitation. This preliminary action ensures that even if moisture is present in the protective film under high humidity conditions, the oxide precipitation is prevented by the pre-established floating well region, maintaining oxidation resistance while preserving the protective function.
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 prevents oxide precipitation on the semiconductor layer's outer peripheral side, ensuring a reliable semiconductor device by preventing peeling of the resin layer and reducing element defects.
Implementation Method 1
a floating well region spaced apart from the termination well region in a surface layer of the semiconductor layer, the floating well region formed to be in contact with an outer peripheral end of the field insulating film to extend to an outer side with respect to an outer peripheral end of the field insulating film, the floating well region having a floating potential
Data Source
AI summary
An object of the present invention is to provide a highly reliable semiconductor device by preventing precipitation of an oxide to prevent peeling of a resin layer. The semiconductor device includes: a resin layer provided so that at least a part of the resin layer extends on a front surface of a semiconductor layer on an outer peripheral side with respect to an outer peripheral end of a field insulating film; and a floating well region spaced apart from a termination well region in a surface layer of the semiconductor layer, the floating well region formed to be in contact with an outer peripheral end of the field insulating film to extend to the outer peripheral side with respect to the outer peripheral end of the field insulating film.