Trench ESD Protection Structure for Semiconductor Devices
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Solution Overview
Problem
Existing semiconductor devices face challenges in achieving enhanced electrostatic discharge (ESD) protection while minimizing the area consumption and thermal impedance of ESD structures, particularly in automotive and industrial applications where solid-state switches like MOSFETs and IGBTs are used.
Innovation Solution
A semiconductor device structure is developed with an electrostatic discharge protection structure accommodated in a trench structure, featuring a polycrystalline silicon layer with alternating regions of opposite conductivity types forming a back-to-back diode chain, which is electrically connected to source and gate contact structures, reducing surface topology and thermal impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ESD protection structures are provided to protect transistors from electrostatic discharge, then ESD robustness is improved, but area consumption increases
Solution Approach 1:
The ESD protection structure is transitioned from a planar configuration to a three-dimensional trench-based configuration. The trench extends vertically into the semiconductor body, allowing the ESD protection elements to be arranged in the depth dimension rather than only in the planar surface area, thereby reducing the lateral footprint while maintaining protection capability
Solution Approach 2:
The ESD protection structure is nested within the trench structure that is formed in the semiconductor body. The protection elements are contained within the trench, which is embedded in the semiconductor substrate, effectively nesting the ESD protection function within the existing device architecture without requiring additional external space
2Reliability
If ESD protection structures are provided to protect transistors from electrostatic discharge, then ESD robustness is improved, but thermal impedance increases
Solution Approach 1:
A conductive material is introduced as an intermediary substance filling the trench structure. This conductive material serves as a thermal pathway that conducts heat away from the ESD protection elements, thereby reducing thermal impedance while maintaining the ESD protection function
Solution Approach 2:
The thermal conductivity parameter of the trench filling material is optimized to enhance heat dissipation. By selecting and configuring materials with appropriate thermal conductivity properties, the thermal impedance of the ESD structure is reduced, allowing for better thermal management during ESD events
3Area of stationary object
If the area of ESD protection structure is reduced, then area efficiency is improved, but thermoelectric safe operating area decreases
Solution Approach 1:
The ESD protection structure utilizes the vertical dimension by implementing a trench configuration that extends into the semiconductor body. This dimensional transition allows the structure to achieve compact lateral footprint while maintaining sufficient volume for adequate thermal management and ESD protection performance
4Reliability
If conventional ESD structures are used, then ESD protection is provided, but topology complexity increases
Solution Approach 1:
The ESD protection structure is merged with the trench structure formed in the semiconductor body. The trench serves dual purposes: providing mechanical support and housing the ESD protection elements, thereby combining structural and protective functions into a single integrated feature that reduces overall topology complexity
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 solution provides robust ESD protection with optimized area efficiency and reduced thermal impedance, enhancing the safe operating area and ESD robustness without increasing the chip area or adding additional process steps, thus improving the reliability of semiconductor devices in harsh environments.
Implementation Method 1
a damage of a gate dielectric between gate and source of the transistors may be caused by an electrostatic discharge event between a gate contact area and a source contact area of the semiconductor device
Implementation Method 2
A semiconductor device structure is developed with an electrostatic discharge protection structure accommodated in a trench structure, featuring a polycrystalline silicon layer with alternating regions of opposite conductivity types forming a back-to-back diode chain
Implementation Method 3
reducing surface topology and thermal impedance
Data Source
AI summary
A semiconductor device includes a semiconductor body having a first surface and a second surface opposite to the first surface. A transistor structure is formed is the semiconductor body. A trench structure extends from the first surface into the semiconductor body. An electrostatic discharge protection structure is accommodated in the trench structure. The electrostatic discharge protection structure includes a first terminal region and a second terminal region. A source contact structure at the first surface is electrically connected to source regions of the transistor structure and to the first terminal region. A gate contact structure at the first surface is electrically connected to a gate electrode of the transistor structure and to the second terminal region.