MuGFET Cooling Elements for ESD Thermal Management
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Solution Overview
Problem
Multigate (MuGFET) or FinFET devices face challenges in dissipating heat effectively during electrostatic discharge events due to their low thermal mass and the blocking effect of the buried oxide layer, which can lead to extreme heating and potential damage.
Innovation Solution
The introduction of cooling elements such as dummy contacts, bar contacts, and gate extensions placed in close proximity to the fins or above active gate regions, which provide additional thermal mass and enhance heat transfer through the use of materials with higher specific heat capacity, such as tungsten, to absorb and dissipate heat generated during transient current flows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If MuGFET devices are designed for high-speed logic core applications with low supply voltages, then device performance and speed are improved, but the devices become more susceptible to damage from electrostatic discharge events due to low thermal mass
Solution Approach 1:
The device structure is segmented into multiple fins (e.g., four fins) that are spaced apart from each other. This segmentation allows for better heat dissipation pathways and reduces the thermal mass concentration in any single region, thereby improving ESD resistance while maintaining high-speed performance through the multi-finger parallel configuration.
Solution Approach 2:
A dummy contact structure is introduced as an intermediary element between the signal contacts and the substrate. This dummy contact serves as a thermal intermediary that absorbs and dissipates heat generated during ESD events, protecting the active device regions while not interfering with the normal high-speed operation of the MuGFET.
2Reliability
If the buried oxide layer is used to isolate the device, then device isolation and electrical performance are improved, but heat dissipation is blocked leading to extreme heating during transient current flows
Solution Approach 1:
The dummy contact structure is extracted from the active device region and placed in the open space between fins. This separate structure can thermally couple to the fins through the oxide layer without compromising the electrical isolation provided by the buried oxide, thereby enabling heat dissipation while maintaining device isolation.
Solution Approach 2:
The dummy contact structure serves multiple functions: it acts as an electrical contact for biasing purposes and simultaneously serves as a thermal sink for heat dissipation during ESD events. This multi-functionality allows the same structure to address both isolation and heat dissipation requirements.
3Temperature
If cooling elements are added to increase thermal mass, then heat dissipation capability is improved, but device complexity and manufacturing steps increase
Solution Approach 1:
The dummy contact structure is merged with the existing contact formation process. The same tungsten deposition and etch steps used to create signal contacts are also used to create the dummy contacts, eliminating the need for separate manufacturing steps and reducing overall device complexity despite the added functional element.
Solution Approach 2:
The dummy contact structure serves itself by utilizing the same material properties (tungsten's high thermal conductivity and high melting point) that make it suitable for electrical contacts. The structure automatically provides thermal management benefits without requiring additional materials or complex fabrication processes.
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
These cooling elements effectively increase the thermal capacity of the semiconductor device, preventing damage from excessive heating during electrostatic discharge events by providing an efficient heat dissipation path, thereby ensuring reliable operation of MuGFET devices.
Implementation Method 1
provide additional thermal mass and enhance heat transfer through the use of materials with higher specific heat capacity, such as tungsten, to absorb and dissipate heat generated during transient current flows
Data Source
AI summary
Some embodiments discussed herein include a semiconductor having a source region, a drain region and an array of fins operatively coupled to a gate region controlling current flow through the fins between the source region and the drain region. The semiconductor also has at least one cooling element formed at least in part of a material having a heat capacity equal to or larger than the heat capacity of the material of the source region, drain region and array of fins, the cooling elements being in close vicinity to fins of the array of fins electrically isolated from the fins of the array, the source region and the drain region. Other embodiments are also disclosed.