Trenched Power Semiconductor Schottky Diode Switching Loss
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Solution Overview
Problem
Trenched power semiconductor devices face switching loss due to the slow conduction of body diodes caused by minority carriers, leading to unwanted time delays in high-frequency applications.
Innovation Solution
A fabrication method is developed to create a trenched power semiconductor structure with a parallel-connected Schottky diode, using conventional semiconductor fabrication technologies to form a narrow trench and a metal layer that electrically connects the source, body, and drain regions, forming a Schottky barrier diode at the interface between the metal layer and the drain region, thereby reducing switching loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a body diode is used in the power semiconductor structure, then the device can provide rectification function, but the switching speed is slow due to minority carriers causing time delay and switching loss
Solution Approach 1:
The patent combines a body diode and a Schottky diode into a single integrated structure. The Schottky diode is formed by creating a contact window through the body to expose the drain region, then filling it with a metal layer to form a Schottky barrier. This merged structure allows the device to maintain rectification functionality while achieving fast switching speed through the Schottky diode's majority carrier conduction mechanism.
2Speed
If a Schottky diode is added to improve switching speed, then switching loss is reduced, but the device structure becomes more complex
Solution Approach 1:
The patent segments the diode structure into two functional parts: the body diode region and the Schottky diode region. The Schottky diode is formed by creating a contact window through the body and filling it with metal to form a Schottky barrier at the metal-semiconductor interface. This segmentation allows the fast switching Schottky diode to be integrated without completely redesigning the existing body diode structure.
Solution Approach 2:
The patent uses a contact window as an intermediary structure to integrate the Schottky diode. The contact window is formed through the body to expose the drain region, and the metal layer filling this window creates the Schottky barrier. This intermediary approach allows the Schottky diode to be added without disrupting the existing body diode structure, thereby reducing the increase in device complexity.
3Ease of manufacture
If conventional fabrication technologies are used to manufacture the trenched power transistor, then manufacturing process is simple, but it is difficult to simultaneously form a parallel-connected Schottky diode
Solution Approach 1:
The patent performs preliminary actions during the standard fabrication process to enable Schottky diode formation. Specifically, the body is etched to form a contact window that exposes the drain region before the metal layer is deposited. This preliminary preparation of the contact window allows the Schottky barrier to be formed naturally when the metal layer is applied, without requiring additional specialized fabrication steps.
Solution Approach 2:
The patent uses the existing fabrication structures and processes to serve the dual purpose of creating both the body diode and the Schottky diode. The contact window formation and metal layer deposition steps, which are part of the conventional fabrication process, automatically create the Schottky barrier structure. This self-service approach allows the Schottky diode to be formed using standard fabrication technologies without requiring additional complex equipment or processes.
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 method effectively reduces switching loss and prevents time delays by utilizing the Schottky diode's faster conduction characteristics, improving the performance of trenched power semiconductor devices in high-frequency applications.
Implementation Method 1
a schottky diode is formed at the interface between the metal layer and the drain region
Data Source
AI summary
A fabrication method of a trenched power semiconductor structure with a schottky diode is provided. Firstly, a drain region is formed in a substrate. Next, at least two gate structures are formed above the drain region, and then, a body and at least a source region are formed between the two adjacent gate structures. Thereafter, a first dielectric structure is formed on the gate structure to shield the gate structure. Then, a contact window is formed in the body and has side surface thereof adjacent to the source region to expose the source region. Afterward, a second dielectric structure is formed in the contact window. Next, by using the second dielectric structure as an etching mask, the body is etched to form a narrow trench extending to the drain region below the body. Finally, a metal layer is filled into the contact window and the narrow trench.