FET ESD Protection via Extraction Electrode and Doped Regions
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Solution Overview
Problem
Existing semiconductor devices face challenges in effectively protecting against electrostatic discharge (ESD) without increasing production costs, as additional components like diodes are required for ESD protection, leading to potential breakdown and heat generation.
Innovation Solution
A field-effect transistor design that includes a gate electrode on a first-conductivity-type region of a semiconductor substrate with an insulating film, source and drain regions of a second conductivity type, a high-concentration first conductivity type region below the drain, and a high-concentration second region reaching the surface, along with an extraction electrode to divert surge current and prevent bipolar operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a diode and MOS transistor are added as ESD protection elements, then ESD resistance is improved, but production cost increases
Solution Approach 1:
The patent merges the ESD protection function with the existing field-effect transistor structure by adding a first region below the drain region and a second region reaching the surface, both of first conductivity type. This integration allows the transistor itself to provide ESD protection through controlled breakdown mechanisms without requiring separate diode or transistor components, thereby reducing device complexity and production cost while maintaining ESD resistance.
2Reliability
If additional ESD protection elements are provided, then ESD resistance is improved, but the number of components increases
Solution Approach 1:
The field-effect transistor is designed to perform multiple functions: normal switching operation and ESD protection. The first region (higher concentration than the first-conductivity-type region) and second region (reaching the surface) enable the transistor to handle ESD events through controlled breakdown, allowing a single component to serve dual purposes and reducing the total number of components needed in the circuit.
3Reliability
If breakdown occurs during ESD events, then surge current is handled, but heat generation breaks the transistor
Solution Approach 1:
The patent implements preliminary protective structures (first region and second region) that are prepared in advance within the transistor. During ESD events, these pre-positioned regions control the breakdown process and provide designated paths for surge current, preventing uncontrolled breakdown that would generate excessive heat. The extraction electrode connected to the second region further facilitates controlled current diversion, managing heat generation before it can damage the transistor.
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
This design enhances ESD resistance in field-effect transistors and semiconductor devices by preventing breakdown and heat generation, reducing the need for additional protection elements and lowering production costs.
Implementation Method 1
a first region of the first conductivity type provided below the drain region and having a higher concentration than the first-conductivity-type region; a second region of the first conductivity type provided to reach a surface in the semiconductor substrate on the other side and having a higher concentration than the first-conductivity-type region; and an extraction electrode connected to the second region
Data Source
AI summary
A field-effect transistor including a gate electrode provided on a first-conductivity-type region of a semiconductor substrate with an insulating film provided between the gate electrode and the first-conductivity-type region, a source region of a second conductivity type provided in the semiconductor substrate on one of sides across the gate electrode, a drain region of the second conductivity type provided in the semiconductor substrate on the other of the sides, the other side facing the one side across the gate electrode, a first region of the first conductivity type provided below the drain region and having a higher concentration than the first-conductivity-type region, a second region of the first conductivity type provided to reach a surface in the semiconductor substrate on the other side and having a higher concentration than the first-conductivity-type region, and an extraction electrode connected to the second region.