Multi-Stage Protection Element for Steep Voltage Surges
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Solution Overview
Problem
Conventional semiconductor devices with protection elements can malfunction and allow a large current flow when a voltage at a terminal connected to the protection element increases steeply, leading to potential damage.
Innovation Solution
A semiconductor device configuration that includes a semiconductor base body, a well region of a second conductivity-type, and a protection element with transistors at multiple stages, where the carrier reception region of the frontmost stage is connected to a first pad, and the carrier supply and gate electrode of the rearmost stage are connected to a second pad via a wire, preventing excessive current flow by controlling voltage distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protection element is connected to a terminal to protect against surge voltage, then the internal circuit is protected, but the protection element itself may malfunction and allow large current flow when voltage steeply increases
Solution Approach 1:
The protection element is divided into multiple stages with different transistors (first transistor, second transistor, third transistor) that activate at different voltage levels. This segmentation allows the protection mechanism to respond differently to various voltage surge intensities, preventing malfunction while maintaining protection capability.
Solution Approach 2:
The patent changes the operational parameters of the protection element by introducing multiple transistors with different threshold voltages and connection configurations. The first transistor connects gate to source, the second transistor has gate connected to drain, and the third transistor has gate shorted to source, creating a progressive response to voltage changes that prevents excessive current while maintaining protection.
2Speed
If the gate electrode and carrier supply region are directly connected, then the transistor responds quickly to voltage changes, but the protection element malfunctions during steep voltage increases
Solution Approach 1:
The protection element is divided into multiple stages with different transistors that activate at different voltage levels. This segmentation allows the system to maintain fast response for normal voltage changes while preventing malfunction during steep voltage increases through the progressive activation of different transistor stages.
Solution Approach 2:
The patent introduces intermediate connection structures between the gate electrode and carrier supply region. Instead of direct connection, the gate is connected through controlled pathways that include multiple transistor stages, acting as intermediaries that filter out harmful steep voltage changes while allowing normal signal transmission.
3Device complexity
If a single-stage protection element is used, then the device complexity is low, but the protection element cannot handle steep voltage increases without malfunctioning
Solution Approach 1:
The protection element is divided into multiple stages with different transistors that activate at different voltage levels. This segmentation enables the system to handle steep voltage increases by distributing the protection function across multiple components, with each transistor managing a specific voltage range, thereby improving reliability without excessive complexity.
Solution Approach 2:
The patent employs a nested structure where multiple transistors are arranged in series stages within the protection element. The first transistor stage handles lower voltage surges, the second stage handles medium voltage surges, and the third stage handles high voltage surges, creating a nested protection hierarchy that improves reliability while maintaining manageable device complexity.
Data Source
AI summary
A semiconductor device includes: a semiconductor base body of a first conductivity-type; a first well region of a second conductivity-type provided at an upper part of the semiconductor base body; a protection element provided in the first well region and including transistors arranged at several stages each including a carrier supply region and a gate electrode mutually short-circuited; a VCC pad provided on a top surface side of the semiconductor base body; and an AGND pad provided on the top surface side of the semiconductor base body, wherein a carrier reception region of the transistor at a frontmost stage included in the protection element is connected to the VCC pad, and the carrier supply region and the gate electrode of the transistor at a rearmost stage included in the protection element are connected to the AGND pad via a first wire.