Trench Gate Semiconductor Device Electric Field Relaxation Layer
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Solution Overview
Problem
Conventional semiconductor devices with trench gate structures face challenges in enhancing dynamic breakdown voltage due to electric field concentration at the interface between the base and accumulation regions, leading to unsaturated collector current and reduced FBSOA withstand capability.
Innovation Solution
Incorporating an electric-field relaxation layer with a lower doping concentration than the accumulation region, positioned between the base and accumulation regions, to deconcentrate the electric field and improve breakdown voltage, while maintaining a thickness equal to or smaller than the accumulation region to prevent excessive field concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an accumulation region with high doping concentration is provided to reduce ON resistance, then the ON resistance decreases, but electric field concentration occurs at the interface with the base region, reducing dynamic breakdown voltage
Solution Approach 1:
An electric-field relaxation layer with intermediate doping concentration is introduced between the high-doping accumulation region and the base region. This intermediary layer acts as a buffer that prevents direct contact between the high-doping accumulation region and the base region, thereby eliminating the electric field concentration at their interface while maintaining the low ON resistance property of the accumulation region.
Solution Approach 2:
The doping concentration parameter is gradually changed from the high doping concentration of the accumulation region to the lower doping concentration of the base region through the electric-field relaxation layer. This gradual parameter transition prevents abrupt changes in electric field distribution, thereby maintaining both low ON resistance and high dynamic breakdown voltage.
2Quantity of substance
If the thickness of the accumulation region is increased to improve carrier accumulation, then the carrier accumulation effect improves, but electric field concentration at the interface increases, reducing breakdown voltage
Solution Approach 1:
The electric-field relaxation layer serves as an intermediary between the accumulation region and the base region, allowing the accumulation region to maintain its optimal thickness for carrier accumulation without causing excessive electric field concentration at the interface with the base region.
3Productivity
If a trench gate structure is used to improve device performance, then switching characteristics improve, but electric field concentration occurs at the base-accumulation region interface, reducing FBSOA withstand capability
Solution Approach 1:
The electric-field relaxation layer acts as a mediator in the trench gate structure, positioned between the base region and accumulation region to prevent electric field concentration at their interface, thereby maintaining both good switching characteristics and high FBSOA withstand capability.
4Power
If avalanche current is allowed to occur at high collector-emitter voltages, then the device can operate at higher voltages, but unsaturated collector current occurs and FBSOA withstand capability is reduced
Solution Approach 1:
The electric-field relaxation layer provides preliminary protection by preventing electric field concentration before avalanche current can occur. By eliminating the condition that leads to avalanche breakdown (electric field concentration at the interface), the device can maintain saturated collector current and high FBSOA withstand capability even at high collector-emitter voltages.
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 electric-field relaxation layer effectively inhibits avalanche current generation at high collector-emitter voltages, ensuring saturated collector current and improved dynamic breakdown voltage, thus enhancing the FBSOA withstand capability and reducing ON resistance.
Implementation Method 1
an electric-field relaxation layer provided between the accumulation region and the base region... to deconcentrate the electric field and improve breakdown voltage
Data Source
AI summary
A semiconductor device having a trench gate structure is provided. A semiconductor device is provided, including: a first-conductivity-type drift region provided in a semiconductor substrate; a first-conductivity-type accumulation region provided above the drift region and having a higher doping concentration than the drift region; a second-conductivity-type base region provided above the accumulation region; and an electric-field relaxation layer provided between the accumulation region and the base region and having a lower doping concentration than the accumulation region. The electric-field relaxation layer may include a first-conductivity-type region including a region having a same doping concentration as the drift region.