Vertical Bidirectional Switch Gate Via Design
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Solution Overview
Problem
Existing bidirectional switches with gate electrodes referenced to the rear surface face challenges in surface area utilization and latch-up issues due to abrupt voltage variations between main electrodes, particularly when operating in Q1 and Q4 modes.
Innovation Solution
A vertical bidirectional switch design with a gate electrode on the front surface of a via crossing the chip, featuring a semiconductor substrate of one conductivity type surrounded by a wall of another conductivity type, including specific regions and layers to control current flow and minimize latch-up, allowing operation in all four quadrants without relying on transistors or lateral thyristors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transistor or lateral thyristor is used for turning on the bidirectional switch in Q1 and Q4 modes, then the switching function is achieved, but the surface area is increased and latch-up problems occur due to abrupt voltage variations
Solution Approach 1:
The patent removes the transistor or lateral thyristor components from the control structure, extracting the problematic elements that caused latch-up issues and excessive surface area usage. The bidirectional switch is turned on directly through the gate electrode without requiring these intermediate switching components, thereby eliminating the latch-up sensitivity while maintaining Q1 and Q4 mode operation.
2Area of moving object
If a transistor or lateral thyristor is used for turning on the bidirectional switch, then the switching function is achieved, but the surface area assigned to the gate is increased
Solution Approach 1:
The patent extracts and removes the transistor or lateral thyristor components that occupied additional surface area. By eliminating these intermediate switching elements, the gate surface area is reduced while the direct gate control mechanism maintains full switching functionality in Q1 and Q4 modes, improving both area utilization and operational simplicity.
3Device complexity
If the gate electrode is referenced to the front surface, then the control is simplified, but isolation systems are required to deliver voltage between control signal and variable potential
Solution Approach 1:
The patent inverts the conventional gate reference approach by referencing the gate electrode to the rear surface instead of the front surface. This inversion eliminates the need for isolation systems between the control signal and variable potential, as the rear surface reference provides a stable potential without requiring additional isolation components, thereby simplifying both control structure and manufacturing.
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 provides a simple, low-bulk control structure that is less sensitive to latch-ups and enables reliable operation across all quadrants without the issues associated with transistor or lateral thyristor turn-on, ensuring stable performance under varying voltage conditions.
Implementation Method 1
a via of the second conductivity type running from the front surface to the rear surface of the substrate, arranged between the first region and the wall, this via being in contact with the gate electrode
Implementation Method 2
an insulating layer being arranged on the rear surface, around the via region
Implementation Method 3
a semiconductor substrate of a first conductivity type surrounded with a wall of the second conductivity type, on the front surface side, a well of the second conductivity type in substantially half of which is formed a first region of the first conductivity type
Data Source
AI summary
A vertical bidirectional switch of the type having its control referenced to the rear surface, including on its rear surface a first main electrode and on its front surface a second main electrode and a gate electrode, this switch being controllable by a positive voltage between its gate and its first electrode, wherein the gate electrode is arranged on the front surface of a via crossing the chip in which the switch is formed.