Transistor Field Electrode Rectifier Voltage Spike Control
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Solution Overview
Problem
Transistor devices with field electrodes experience voltage spikes due to charging of the capacitor formed by the field electrode, field electrode dielectric, and drift region, which can exceed the voltage blocking capability, necessitating a solution to reduce or eliminate these spikes.
Innovation Solution
Incorporating a rectifier element and a resistive element between the source electrode and the field electrode, with the rectifier element connected between the source electrode and the field electrode structure, allowing the resistive element to govern charging and the rectifier element to govern discharging, thereby controlling the charging current and reducing voltage spikes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a field electrode is implemented to increase doping concentration without decreasing voltage blocking capability, then on-resistance decreases, but voltage spikes occur due to capacitor charging
Solution Approach 1:
A rectifier element is introduced as an intermediary component between the field electrode and source electrode. This rectifier element selectively blocks the charging current of the capacitor formed by the field electrode structure, thereby preventing voltage spikes while allowing the field electrode to maintain its voltage blocking capability enhancement function
Solution Approach 2:
The charging current path of the capacitor is extracted and blocked by the rectifier element, separating the charging function from the discharging function. The rectifier element allows the capacitor to discharge through the drift region during normal operation while preventing recharging that would cause voltage spikes
2Reliability
If doping concentration in drift region is increased to decrease on-resistance, then on-resistance decreases, but voltage blocking capability decreases
Solution Approach 1:
The field electrode structure provides self-service by generating an electric field that compensates for the reduced dopant charge in the drift region. This allows the drift region to be more highly doped (reducing on-resistance) while the field electrode compensates to maintain the required voltage blocking capability
Solution Approach 2:
The invention changes the electrical parameters of the drift region by introducing a compensating electric field from the field electrode. This allows optimization of the doping concentration parameter to reduce on-resistance while the field electrode parameter compensates to maintain voltage blocking capability
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 implementation of a rectifier and resistive element effectively limits the maximum charging current and attenuates oscillations, reducing voltage spikes and maintaining the voltage blocking capability while decreasing on-resistance.
Implementation Method 1
a rectifier element coupled between the source electrode and the field electrode... governing charging and discharging of the capacitor
Implementation Method 2
the resistive element to govern charging and discharging, thereby controlling the charging current
Implementation Method 3
at least one field electrode dielectrically insulated from the drift region by a field electrode dielectric
Implementation Method 4
a gate electrode dielectrically insulated from the body region by a gate dielectric
Data Source
Figure 1~4
Figure 5~6
Figure 7~12
AI summary
Disclosed is a transistor device. The transistor device includes: in a semiconductor body (100), a drift region (11), a body region (12) adjoining the drift region (11), and a source region (13) separated from the drift region (11) by the body region (12); a gate electrode (21) dielectrically insulated from the body region (12) by a gate dielectric (22); a source electrode (41) electrically connected to the source region (13); at least one field electrode (31) dielectrically insulated from the drift region (11) by a field electrode dielectric (32); and a rectifier element (5) coupled between the source electrode (41) and the field electrode (31). The field electrode (31) and the field electrode dielectric (32) are arranged in a first trench that extends from a first surface (101) of the semiconductor body (100) into the semiconductor body (100), and the rectifier element (5) is integrated in the first trench in a rectifier region (110) that is adjacent at least one of the source region (13) and the body region (12).