Transistor Wing Structure Reduces Electron Trapping
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Solution Overview
Problem
Medium and high voltage transistor devices face challenges with electrical performance and integration due to electron trapping caused by impact ionization, leading to degradation of breakdown voltage and threshold voltage, especially in transistors with channel widths between 0.42 microns to 2 microns, which increases manufacturing costs with multiple photomasks and lithography operations.
Innovation Solution
The introduction of wing regions in the transistor active region, formed with the same materials and doping as the channel region, using a single photomask to minimize lithography operations, which shifts the corner electric field away from the channel, reducing electron trapping and maintaining the channel region under the gate electrode to prevent short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lightly doped well implants are employed to optimize breakdown voltage, then electrical performance is improved, but manufacturing cost increases due to multiple photomasks and lithography operations
Solution Approach 1:
The patent extracts the light doping step from the manufacturing process by using a heavily doped well instead of lightly doped wells, eliminating the need for multiple photomasks and lithography operations while maintaining breakdown voltage performance
Solution Approach 2:
The patent changes the doping concentration parameter from light doping to heavy doping in the well region, which fundamentally alters the electrical characteristics and eliminates the need for additional lithography steps to create graded doping profiles
2Reliability
If multiple light well doping concentrations are used to increase breakdown voltage, then electrical performance is improved, but device complexity increases due to several photomasks
Solution Approach 1:
The patent removes the complex multi-step doping process by using a single heavily doped well, extracting the unnecessary intermediate light doping steps and their associated photomasks from the manufacturing process
Solution Approach 2:
The patent combines multiple doping functions into a single heavily doped well structure, merging the roles of multiple lightly doped wells into one structure that achieves the same electrical performance with simpler fabrication
3Object-affected harmful factors
If wing regions are introduced to shift corner electric field, then electron trapping is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality by creating wing regions with the same doping as the channel region in specific locations adjacent to the channel, locally modifying the electric field distribution without requiring global process changes or high-precision alignment
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 reduces electron trapping, minimizing resistance and maintaining transistor performance without increasing manufacturing costs by using fewer photomasks and reducing the deleterious effects of impact ionization, thus maintaining the breakdown voltage and threshold voltage.
Implementation Method 1
shifts the corner electric field away from the channel
Implementation Method 2
reducing electron trapping and maintaining the channel region under the gate electrode to prevent short circuits
Data Source
AI summary
A semiconductor device includes an active region having a channel region and at least a wing region adjoining the channel region under the gate dielectric layer. The at least one wing region may be two symmetrical wing regions across the channel region.