Semiconductor Component With Schottky Device And Epitaxial Layer
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Solution Overview
Problem
High voltage power switching devices face a trade-off between breakdown voltage and on-state resistance, leading to increased switching losses due to reverse recovery time and charge storage in P-N diodes, which delays switching speed and causes voltage level losses.
Innovation Solution
A semiconductor component with a Schottky device or trench field effect transistor structure is formed using epitaxial layers over a semiconductor substrate, where the top epitaxial layer has higher resistivity than the substrate, allowing for lower on-state resistance and enhanced breakdown voltage, and edge termination structures are formed to manage charge storage and leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If breakdown voltage is increased to meet high voltage requirements, then breakdown voltage specification is satisfied, but on-state resistance increases leading to higher switching losses
Solution Approach 1:
The device is segmented into two separate devices within a single semiconductor component: a first power switching device (MOSFET) for high voltage switching and a second power switching device (Schottky diode) for rectification. This segmentation allows each device to be optimized for its specific function, with the MOSFET having lower breakdown voltage but lower on-resistance, and the Schottky diode handling the rectification function that would otherwise require a high-voltage P-N diode in a conventional single-device design.
Solution Approach 2:
The patent uses a composite structure combining different semiconductor device types (MOSFET and Schottky diode) with different conductivity types (N-type and P-type epitaxial layers) to achieve overall system performance that neither device could achieve alone. The N-type epitaxial layer provides low on-resistance for the MOSFET, while the P-type epitaxial layer provides the Schottky diode structure with low reverse recovery characteristics.
2Ease of operation
If P-N diode structure is used for rectification, then rectification function is provided, but reverse recovery time increases delaying switching speed
Solution Approach 1:
The rectification function is extracted from the high-voltage power switching device and implemented as a separate Schottky diode. This removes the problematic P-N junction reverse recovery effect from the high-voltage switching path, as the Schottky diode uses a metal-semiconductor junction that does not exhibit significant reverse recovery behavior.
Solution Approach 2:
The patent changes the fundamental parameter of the rectification junction from a P-N junction to a Schottky junction (metal-semiconductor junction). This parameter change eliminates the charge storage and reverse recovery effects inherent in P-N diodes, enabling faster switching speeds without sacrificing rectification functionality.
3Ease of operation
If P-N diode charge storage is present, then rectification is achieved, but reverse recovery current causes voltage level losses
Solution Approach 1:
The patent converts the harmful reverse recovery current effect into a beneficial low-loss operation by using a Schottky diode instead of a P-N diode. The Schottky diode's metal-semiconductor junction inherently prevents charge storage, transforming what would be a harmful reverse recovery phenomenon into a beneficial low reverse recovery current characteristic that reduces voltage level losses.
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 solution reduces switching losses and improves switching speed by lowering reverse recovery time and charge storage, while maintaining cost efficiency in manufacturing.
Implementation Method 1
A semiconductor component with a Schottky device or trench field effect transistor structure is formed using epitaxial layers over a semiconductor substrate
Implementation Method 2
A semiconductor component with a Schottky device or trench field effect transistor structure is formed using epitaxial layers over a semiconductor substrate
Data Source
AI summary
A semiconductor component that includes a Schottky device, an edge termination structure, a non-Schottky semiconductor device, combinations thereof and a method of manufacturing the semiconductor component. A semiconductor material includes a first epitaxial layer disposed on a semiconductor substrate and a second epitaxial layer disposed on the first epitaxial layer. The second epitaxial layer has a higher resistivity than the semiconductor substrate. A Schottky device and a non-Schottky semiconductor device are manufactured from the second epitaxial layer. In accordance with another embodiment, a semiconductor material includes an epitaxial layer disposed over a semiconductor substrate. The epitaxial layer has a higher resistivity than the semiconductor substrate. A doped region is formed in the epitaxial layer. A Schottky device and a non-Schottky semiconductor device are manufactured from the epitaxial layer.