Ultra-high Voltage Polysilicon Resistor Integration
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Solution Overview
Problem
Existing ultra-high voltage circuits for AC/DC power conversion require effective self-biasing and start-up mechanisms from high-voltage DC supplies, often relying on discrete resistors or transistors, which are costly and inefficient in terms of layout area and mask usage in the fabrication process.
Innovation Solution
Integration of polysilicon resistors within a CMOS process over a high-voltage N-well in a lightly doped P-type substrate, separated by a dielectric layer, with one end attached to a high-voltage input pad and the other to low-voltage circuitry, allowing for series connection and spiral configurations to manage voltage drops effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If discrete high-value resistors are placed on the PCB for UHV start-up, then reliable self-biasing is achieved, but layout area and manufacturing cost increase
Solution Approach 1:
The patent combines the discrete resistor function directly into the IC chip by integrating a high-value resistor (100 kΩ to 10 MΩ) within the CMOS process, merging two separate components (resistor and IC) into a single integrated structure, thereby eliminating the need for external PCB resistors and reducing layout area
Solution Approach 2:
The integrated resistor structure serves multiple functions: it provides the high-value resistance for start-up current limitation, enables self-biasing operation, and integrates within the standard CMOS fabrication process, making the IC chip universally applicable for UHV power conversion applications without requiring additional discrete components
2Ease of operation
If discrete high-value resistors are used for UHV circuits, then start-up function is achieved, but manufacturing cost increases
Solution Approach 1:
The patent merges the start-up resistor function into the IC chip fabrication process itself, using the same CMOS manufacturing steps to create both the active circuitry and the high-value resistor, thereby eliminating the need for separate discrete components and reducing overall manufacturing cost
Solution Approach 2:
The patent achieves high resistance values (100 kΩ to 10 MΩ) by carefully controlling the resistor geometry and doping parameters during CMOS fabrication, specifically by creating long and narrow resistor paths with appropriate doping concentrations, thereby achieving the required electrical characteristics through parameter optimization rather than using expensive discrete components
3Ease of operation
If normally-ON ultra-high voltage transistors are used for start-up, then start-up function is achieved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the start-up function from the complex normally-ON transistor approach and implements it through a simple integrated high-value resistor, removing the need for additional transistors and associated control circuitry, thereby simplifying the overall device structure while maintaining the required start-up functionality
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 reduces wafer costs by minimizing resistor size and mask requirements, enabling reliable ultra-high voltage ratings over 400 V and substituting for normally-ON transistors in cost-sensitive applications, while maintaining reliable dielectric layers and temperature coefficients.
Implementation Method 1
separated vertically by a dielectric material
Data Source
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to an ultra-high voltage resistor and methods of manufacture. The structure includes at least one resistor coupled to a well of a doped substrate, the at least one resistor being separated vertically from the well by an isolation region with one end of the resistor being attached to an input pad and another end coupled to circuitry.