Multigate LDMOS Breakdown Voltage via Fin Segmentation
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Solution Overview
Problem
Integrated circuits face transistor breakdown due to operating voltages exceeding the breakdown voltage, leading to increased current and reduced transistor lifetime, particularly in auxiliary devices like printers and scanners.
Innovation Solution
The implementation of a multigate laterally diffused metal oxide semiconductor (LDMOS) structure with strategically placed semiconductor fins and gaps, along with epitaxial growth and different doping densities, enhances the breakdown voltage by creating a gap between the gate and drain structures, and using spacers and fin structures to manage carrier concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If operating voltages are increased above transistor breakdown voltage, then power and performance are improved, but transistor reliability deteriorates due to breakdown effects
Solution Approach 1:
The drain region is segmented into multiple zones with different doping concentrations (first doping concentration in the drift region, second doping concentration in the lightly doped drain region). This segmentation allows the device to handle higher voltages by distributing the electric field stress across multiple regions, preventing breakdown while maintaining high power capability.
Solution Approach 2:
Different regions of the transistor are assigned different doping concentrations to optimize local properties. The drift region has a first doping concentration optimized for high voltage blocking, while the lightly doped drain region has a second doping concentration optimized for carrier transport. This local quality differentiation allows the transistor to operate at higher voltages without breakdown.
2Reliability
If higher doping concentrations are used to reduce resistance, then conductivity is improved, but breakdown voltage decreases
Solution Approach 1:
The patent employs multiple doping concentration parameters (first doping concentration in the drift region, second doping concentration in the LDD region) with specific relationships between them. By carefully controlling these parameters and their ratios, the device achieves optimal balance between conductivity and breakdown voltage, preventing premature breakdown while maintaining low resistance.
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 configuration effectively increases the breakdown voltage and extends the lifespan of transistors by controlling current flow and reducing the risk of punch-through and gate oxide breakdown.
Implementation Method 1
A semiconductor layer is implanted in a substrate
Implementation Method 2
epitaxial growth and different doping densities
Data Source
AI summary
A semiconductor device includes a first well and a second well implanted in a semiconductor substrate. The semiconductor device further includes a gate structure above the first and second wells between a raised source structure and a raised drain structure. The raised source structure above is in contact with the first well and connected with the gate structure through a first semiconductor fin structure. The raised drain structure above and in contact with the second well and connected with a second semiconductor fin structure. The second semiconductor fin structure includes at least a gap and a lightly doped portion.