SiC Semiconductor Device with Segmented Field Limiting Rings
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Solution Overview
Problem
The existing field limiting ring (FLR) structure in semiconductor devices faces challenges with resist collapse during manufacturing, limiting the ability to form close intervals between rings and thereby restricting the increase in withstand voltage due to the narrow line width of the resist masks.
Innovation Solution
The semiconductor device incorporates ring-shaped regions with separation regions of the first conductivity type, where the resists are formed with bridges of varying widths to prevent resist collapse, allowing for closer intervals and effective field relief, using a silicon carbide semiconductor substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the intervals between the rings are made close to increase withstand voltage, then the withstand voltage of the semiconductor device is improved, but the resist line width becomes too narrow causing resist collapse during manufacturing
Solution Approach 1:
The patent divides the continuous ring-shaped resist into multiple separate resist portions by introducing gaps. This segmentation prevents resist collapse while maintaining the ability to form close intervals between the implanted ion regions, thereby achieving both manufacturing feasibility and high withstand voltage performance.
Solution Approach 2:
The patent applies different properties to different parts of the ring structure: the resist is formed with gaps (lower density/discontinuity) in regions where collapse prevention is needed, while the ion implantation creates continuous high-concentration regions where electrical performance is critical. This local differentiation resolves the contradiction between structural integrity and electrical function.
2Reliability
If the resist line width is reduced to achieve close ring intervals, then the withstand voltage is improved, but the resist structure becomes unstable and collapses
Solution Approach 1:
By segmenting the ring resist into discrete portions with gaps between them, the patent eliminates the continuous narrow-line structure that is prone to collapse. Each separate resist portion has sufficient structural stability while the overall pattern maintains the desired close spacing for high withstand voltage.
Solution Approach 2:
The gap regions act as intermediaries between the separate resist portions. These gaps provide mechanical support and stress relief that prevent resist collapse, while allowing the ion implantation process to create the desired continuous electrical structure for high voltage performance.
3Ease of manufacture
If the resist is formed as a continuous ring to ensure structural integrity, then the manufacturability is improved, but the intervals between rings cannot be made close enough to achieve high withstand voltage
Solution Approach 1:
The patent uses segmentation to reconcile manufacturability with performance: the resist is intentionally formed as discontinuous segments rather than a continuous ring. This segmentation makes the resist easier to manufacture without collapse while the ion implantation process ensures the electrical functionality requires continuous high-concentration regions for high withstand voltage.
Solution Approach 2:
The patent performs preliminary resist formation with gaps before ion implantation. This preliminary action establishes a manufacturable resist structure that prevents collapse, and the subsequent ion implantation creates the desired continuous electrical structure, thereby achieving both ease of manufacture and high reliability.
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 suppresses resist collapse and effectively relieves electric field concentration, enabling the formation of semiconductor devices with higher withstand voltage and improved manufacturing yields.
Implementation Method 1
implanting ions into the semiconductor substrate using the resists as a mask
Data Source
AI summary
A semiconductor device including a terminal region that can suppress a resist collapse in manufacturing and effectively relieve a concentration of electric fields and a method for manufacturing the semiconductor device. The semiconductor device includes a semiconductor element formed in a semiconductor substrate made of a silicon carbide semiconductor of a first conductivity type and a plurality of ring-shaped regions of a second conductivity type formed in the semiconductor substrate while surrounding the semiconductor element in plan view. At least one of the plurality of ring-shaped regions includes one or more separation regions of the first conductivity type that cause areas of the first conductivity type on an inner side and an outer side of one of the ring-shaped regions to communicate with each other in plan view.