Schottky Diode Termination Structure for Reverse Breakdown Voltage
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Solution Overview
Problem
Schottky diodes have a low reverse breakdown voltage and high reverse current leakage, leading to thermal instability and high manufacturing costs due to complex manufacturing processes.
Innovation Solution
A diode device with a substrate, epitaxial layer, trench gate electrode structure, and termination structure is developed, featuring a doped region with a conductive type reverse to the epitaxial layer beneath the termination trench, which changes the electric field distribution and increases the reverse breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a Schottky diode is designed to have low forward voltage drop and fast switching, then rectification efficiency and switching speed are improved, but reverse breakdown voltage becomes low and reverse current leakage increases
Solution Approach 1:
The patent divides the semiconductor structure into distinct regions: a first semiconductor region with the Schottky barrier for rectification, and a second semiconductor region with opposite doping type that forms a PN junction for voltage blocking. This segmentation allows each region to specialize in its function without interfering with the other, resolving the contradiction between low forward voltage and high reverse breakdown voltage.
Solution Approach 2:
The patent creates a composite structure combining Schottky barrier characteristics (low forward voltage drop) with PN junction characteristics (high reverse breakdown voltage). The combination of metal-semiconductor Schottky contact and semiconductor-semiconductor PN junction forms a hybrid device that exhibits both low power consumption and high reliability under reverse bias conditions.
2Ease of operation
If Schottky metals with lower barrier are used to decrease turn on voltage, then forward conduction is improved, but reverse current leakage increases due to low reverse breakdown voltage
Solution Approach 1:
The patent introduces a second semiconductor region with opposite doping type as an intermediary between the Schottky barrier and the substrate. This intermediary region forms a PN junction that acts as a mediator to block reverse current, allowing the use of low-barrier Schottky metals for improved turn-on characteristics without suffering from reverse leakage issues.
Solution Approach 2:
The patent changes the electrical parameters of the structure by introducing a region with opposite doping type, which fundamentally alters the reverse bias behavior. The PN junction formed by the doped region creates a high potential barrier that prevents reverse current flow, while maintaining the low forward voltage characteristics of the Schottky barrier.
3Reliability
If the reverse breakdown voltage is increased to reduce reverse current leakage, then thermal stability is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent performs preliminary doping during the epitaxial growth process to create the second semiconductor region with opposite doping type. By incorporating the voltage-blocking functionality into the epitaxial layer formation itself, the need for additional complex post-processing steps is eliminated, maintaining manufacturing simplicity while achieving high reverse breakdown voltage.
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 effectively increases the reverse breakdown voltage of Schottky diodes by 10% and reduces reverse current leakage, enhancing the reliability and reducing manufacturing costs.
Implementation Method 1
by forming a doped region having conductive type reverse to that of the epitaxial layer in the epitaxial layer beneath the termination trench, the diode device and manufacturing method thereof provided by the instant disclosure changes the electric field distribution, increasing the reverse breakdown voltage of the Schottky diode
Implementation Method 2
Schottky diodes utilize the Schottky barrier generated during the bonding of metals and semiconductors, thereby providing the function of rectification
Implementation Method 3
performing a thermal oxidation process for forming an oxidation layer on the inner wall of the termination trench
Data Source
AI summary
A diode device and manufacturing method thereof are provided. The diode device includes a substrate, an epitaxial layer, a trench gate structure, a Schottky diode structure and a termination structure. An active region and a termination region are defined in the epitaxial layer. The Schottky diode structure and the trench gate structure are located in the active region and the termination structure is located in the termination region. The termination structure includes a termination trench formed in the epitaxial layer, a termination insulating layer, a first spacer, a second spacer and a first doped region. The termination insulating layer is conformingly formed on inner walls of the termination trench. The first and second spacers are disposed on two sidewalls of the termination trench. The first doped region formed beneath the termination trench has a conductive type reverse to that of the epitaxial layer.