High Voltage Resistor With Biased Well Breakdown
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Solution Overview
Problem
Conventional high voltage resistors in semiconductor integrated circuits suffer from device breakdown issues due to high voltage potential differences, which limits their effectiveness in handling voltages beyond a certain threshold.
Innovation Solution
A method for fabricating high voltage semiconductor devices involves forming a high voltage N-well with a specific doping polarity, coupled to a polysilicon resistor, where the N-well is electrically biased to a midpoint voltage between the resistor's terminals, allowing it to tolerate higher voltage differences without breakdown, using existing fabrication processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional high voltage resistor structures are used, then manufacturing simplicity is maintained, but device breakdown occurs at lower voltage thresholds
Solution Approach 1:
The device is segmented into distinct functional regions: a first doped well region, a second doped well region, and a drift region positioned between them. This segmentation allows each region to be optimized independently for its specific function, enabling the structure to withstand higher voltages by distributing the electric field stress across multiple zones rather than a single uniform structure.
Solution Approach 2:
Different regions of the device are assigned different doping concentrations and types to optimize local electrical properties. The first doped well has a first doping concentration, the second doped well has a second doping concentration, and the drift region has a third doping concentration. This local differentiation allows each region to perform its specific function optimally, improving overall breakdown voltage performance.
2Reliability
If isolation structure thickness is increased to prevent breakdown, then voltage tolerance improves, but manufacturing complexity and process changes increase
Solution Approach 1:
The device employs dynamically optimized doping profiles where the doping concentrations in different regions are specifically tailored to create an electric field distribution that naturally withstands high voltages. This dynamic optimization of electrical properties through doping, rather than static increases in physical dimensions, allows high voltage tolerance to be achieved without modifying the fundamental isolation structure thickness or manufacturing process flow.
3Productivity
If device geometry is scaled down to increase functional density, then circuit integration improves, but voltage handling capability deteriorates
Solution Approach 1:
The invention changes key electrical parameters, specifically the doping concentrations in different regions, to optimize the electric field distribution. By carefully controlling the doping parameters (first doping concentration, second doping concentration, third doping concentration) in each region, the device achieves high breakdown voltage capability in a compact geometry, allowing both high functional density and high voltage handling to coexist.
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 approach enhances the breakdown performance of high voltage resistors, enabling them to handle voltages up to 730 volts without device failure, while maintaining existing process flow and avoiding the need for increased isolation structure thickness.
Implementation Method 1
a doped well in a substrate, the doped well having a doping polarity opposite the substrate doping polarity
Implementation Method 2
the N-well is electrically biased to a midpoint voltage between the resistor's terminals
Data Source
AI summary
Provided is a high voltage semiconductor device. The semiconductor device includes a doped well located in a substrate that is oppositely doped. The semiconductor device includes a dielectric structure located on the doped well. A portion of the doped well adjacent the dielectric structure has a higher doping concentration than a remaining portion of the doped well. The semiconductor device includes an elongate polysilicon structure located on the dielectric structure. The elongate polysilicon structure has a length L. The portion of the doped well adjacent the dielectric structure is electrically coupled to a segment of the elongate polysilicon structure that is located away from a midpoint of the elongate polysilicon structure by a predetermined distance that is measured along the elongate polysilicon structure. The predetermined distance is in a range from about 0*L to about 0.1*L.