SiGe Diode Integration for Fast Reverse Recovery in MOS Transistors
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Solution Overview
Problem
Pseudo Schottky Diodes experience increased reverse recovery time due to minority carrier contribution at high current densities, which slows down switching times and increases operating power.
Innovation Solution
Integrating a SiGe diode on the MOS transistor device die between the source and drain connections, utilizing a p-type SiGe epitaxial layer and an n-type Si epitaxial layer to reduce forward bias voltage drop and enhance majority carrier conduction, thereby reducing reverse recovery time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a Pseudo Schottky Diode structure is used to achieve fast reverse recovery times, then reverse recovery time is improved, but at high current densities minority carriers contribute to total current and reverse recovery time increases
Solution Approach 1:
The patent changes the material composition parameter by incorporating germanium (Ge) into the silicon (Si) lattice to form SiGe layers. This material parameter change modifies the band structure and carrier transport properties, enabling the diode to maintain fast reverse recovery characteristics even at high current densities where conventional Pseudo Schottky diodes fail due to minority carrier injection
Solution Approach 2:
The patent employs composite SiGe material structure with specific germanium concentration gradients. The composite nature of SiGe (silicon-germanium alloy) allows combining the benefits of silicon's mature processing with germanium's superior carrier mobility and reduced minority carrier injection, thereby resolving the contradiction between fast reverse recovery and high current density performance
2Power
If forward current is dominated by minority carriers in the body pn-junction, then total current is achieved, but reverse recovery time increases and switching times increase
Solution Approach 1:
The patent modifies the material parameter by using SiGe epitaxial layers with controlled germanium content to change the dominant conduction mechanism. The material composition is engineered so that majority carrier conduction predominates even at high forward currents, preventing minority carrier storage and maintaining fast switching times while achieving required current levels
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 SiGe diode achieves faster reverse recovery times and lower operating power by dominating forward current with majority carriers, minimizing minority carrier injection and maintaining low forward voltage drop at high current densities.
Implementation Method 1
utilizing a p-type SiGe epitaxial layer and an n-type Si epitaxial layer to reduce forward bias voltage drop and enhance majority carrier conduction
Implementation Method 2
minimizing minority carrier injection and maintaining low forward voltage drop at high current densities
Data Source
AI summary
This disclosure relates to a semiconductor device and corresponding method of manufacturing the semiconductor device. The semiconductor device includes a MOS transistor device die and a SiGe diode. The SiGe diode is integrally arranged on the MOS transistor device die, so that the SiGe diode is electrically connected between a source connection and drain connection of the MOS transistor device die.