MOSFET ESD Protection with Integrated Voltage-Stabilizing Capacitor
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Solution Overview
Problem
Conventional semiconductor chips require additional space and cost for ESD protection and voltage stabilization, as separate components are needed for these functions, which increases the chip size and expense.
Innovation Solution
A metal-oxide-semiconductor field-effect transistor (MOSFET) is designed with a built-in voltage-stabilizing capacitor formed by a conductor layer, an N-type well, and N-type doping regions, allowing the MOSFET to provide both electrostatic-discharge protection and voltage stabilization without the need for extra chip space or components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate ESD protection devices and voltage-stabilizing capacitors are used, then ESD protection and voltage stabilization functions are achieved, but chip area increases and manufacturing cost increases
Solution Approach 1:
The patent combines the ESD protection device and voltage-stabilizing capacitor into a single integrated structure. The capacitor is formed using the same doped regions (first and second doped regions) and conductive layer that constitute the ESD protection MOSFET, eliminating the need for separate components. This merging allows both ESD protection and voltage stabilization functions to be achieved within the same device footprint, directly resolving the technical contradiction between achieving reliable protection/stabilization and minimizing chip area.
Solution Approach 2:
The MOSFET structure is designed to serve multiple functions: it provides ESD protection through its standard operation while simultaneously functioning as a voltage-stabilizing capacitor when its gate is connected to the power supply voltage. The same physical structure (doped regions, conductive layer, and oxide layer) enables both protection and stabilization, making the device universal and eliminating the need for dedicated separate components for each function.
2Reliability
If separate ESD protection devices and voltage-stabilizing capacitors are used, then ESD protection and voltage stabilization functions are achieved, but manufacturing cost increases
Solution Approach 1:
The patent merges the ESD protection device and voltage-stabilizing capacitor into a single integrated structure formed during the same manufacturing process. The capacitor is created using the same doped regions, conductive layer, and oxide layer that form the ESD protection MOSFET, eliminating the need for additional fabrication steps, materials, or processing. This merging directly reduces manufacturing cost while maintaining both protection and stabilization functions.
Solution Approach 2:
The MOSFET structure is designed to serve multiple functions: it provides ESD protection through its standard operation while simultaneously functioning as a voltage-stabilizing capacitor when its gate is connected to the power supply voltage. The same physical structure (doped regions, conductive layer, and oxide layer) enables both protection and stabilization, making the device universal and eliminating the need for dedicated separate components for each function.
3Reliability
If dummy MOSFET is used for ESD protection, then ESD protection is achieved, but the device does not function during normal operation representing wasted chip resources
Solution Approach 1:
The patent makes the ESD protection device dynamic by enabling it to switch between two operational modes: ESD protection mode during abnormal conditions and voltage-stabilizing capacitor mode during normal operation. The device's function changes based on operating conditions, with the gate connection to power supply voltage enabling capacitor operation during normal conditions. This dynamic behavior eliminates resource waste by ensuring the structure serves a useful function in both protection and normal operation scenarios.
Solution Approach 2:
The MOSFET structure is designed to serve multiple functions: it provides ESD protection through its standard operation while simultaneously functioning as a voltage-stabilizing capacitor when its gate is connected to the power supply voltage. The same physical structure (doped regions, conductive layer, and oxide layer) enables both protection and stabilization, making the device universal and eliminating the need for dedicated separate components for each function.
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 effectively utilizes the MOSFET for both ESD protection and voltage stabilization, reducing chip size and manufacturing costs while enhancing chip performance by integrating these functions into a single structure.
Implementation Method 1
a voltage-stabilizing capacitor formed by a conductor layer, an N-type well, a first N-type doping region, and a second N-type doping region
Implementation Method 2
ESD protection devices used in a chip are generally realized by connecting the pad in a chip to a dummy metal-oxide-semiconductor field-effect transistor (MOSFET) for preventing damage caused by large currents generated by static charges
Data Source
AI summary
The present invention relates to a metal-oxide-semiconductor field-effect transistor (MOSFET) with electrostatic-discharge (ESD) protection and a voltage-stabilizing capacitor, and a method for manufacturing the same and is applied to a chip, including a P-type substrate, a conductor layer, a first N-type doping region, a second N-type doping region, and an N-type well. The conductor layer is coupled to the ground; the first N-type doping region is coupled to the power supply; the second N-type doping region is coupled to a VDD pad (power-supply pad). Thereby, when the chip is not installed or not operating, the MOSFET can be used for ESD protection. When the chip is operating, the conductor layer, the first N-type doping region, the second N-type doing region, and the N-type well form a gate capacitor as a voltage-stabilizing capacitor between the power supply and the ground. Hence, the objective of fully utilization is achieved. In addition, the chip size is saved and thus the cost thereof is reduced.