High-Voltage Power Supply With Transfer Capacitor for Fast Settling
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Solution Overview
Problem
Existing HVDC power supplies struggle to provide rapidly changing voltages and reduce settling times, leading to increased latency and inspection time in electron beam inspection (EBI), scanning electron microscope (SEM), and lithography applications due to capacitive coupling between cables and ground, which causes voltage disturbances and slow stabilization of secondary outputs.
Innovation Solution
A high voltage power supply system incorporating a primary DC source, secondary regulated sources, and a fast power control with a transfer capacitor coupled to ground, utilizing a first and second variable power source to make rapid adjustments and equalize charge across cable capacitances, thereby reducing settling time and enabling faster voltage changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional HVDC power supply architecture is used with primary accelerator and floating secondary outputs, then the system provides stable high voltage power, but the settling time for voltage changes is long due to capacitive coupling and limited bandwidth
Solution Approach 1:
The power supply is divided into multiple independent modules: primary accelerator module, fast power control module, transfer capacitor module, and secondary regulated sources. Each module operates semi-independently, allowing the fast power control module to make rapid adjustments without affecting the stability of the primary accelerator, thus reducing settling time while maintaining reliable power supply.
Solution Approach 2:
A transfer capacitor is introduced as an intermediary element between the primary accelerator and secondary regulated sources. This capacitor acts as a buffer that can rapidly charge and discharge to provide fast voltage changes to the secondary outputs without requiring the primary accelerator to change its output, thereby reducing settling time while maintaining system stability.
2Speed
If rapid voltage changes are implemented in traditional HVDC power supplies, then scanning speed improves, but capacitive coupling causes increased latency and settling time
Solution Approach 1:
The fast power control module pre-charges or pre-discharges the transfer capacitor in anticipation of required voltage changes. By preparing the capacitor state in advance, the system can execute rapid voltage changes at the secondary outputs without experiencing latency from capacitive coupling, thus improving scanning speed without increasing settling time.
Solution Approach 2:
The system changes the operating parameters of the transfer capacitor dynamically - adjusting its charge state, voltage level, and discharge rate based on the required scanning speed and voltage change demands. This parameter optimization allows rapid voltage changes for high scanning speed while managing capacitive coupling effects to minimize latency and settling time.
3Reliability
If filtering is applied to the primary accelerator output to reduce ripple, then power quality improves, but bandwidth is limited preventing fast voltage changes
Solution Approach 1:
The transfer capacitor serves as an intermediary that decouples the filtering requirement from the voltage change speed requirement. The primary accelerator output can be heavily filtered for high power quality, while the transfer capacitor provides the necessary bandwidth and speed for rapid voltage changes at the secondary outputs, resolving the contradiction between power quality and voltage change rate.
Solution Approach 2:
The system segments the power supply function into two distinct paths: one path through the filtered primary accelerator for stable baseline power (high power quality), and another path through the fast power control and transfer capacitor for rapid voltage adjustments (high voltage change rate). This segmentation allows both requirements to be satisfied simultaneously.
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
The system achieves faster scanning speeds and reduced latency by minimizing voltage disturbances and stabilizing secondary outputs more quickly, enhancing the precision and efficiency of EBI, SEM, and lithography tools.
Implementation Method 1
A high voltage power supply and control system for electron beam tools is disclosed including a primary DC source, one or more secondary regulated sources, and a fast power control interposed therebetween including a transfer capacitor coupled to ground
Data Source
AI summary
The disclosure describes a high voltage power supply and control system for electron beam tools. The system includes a primary DC source, one or more secondary regulated sources, and a fast power control interposed therebetween. The fast power control includes a transfer capacitor coupled to ground, a first fast power control, and a second fast power control. The first fast power control makes rapid and small adjustments to the total output provided to the secondaries and hence controls small adjustments to the tool, while the second fast power control makes proportional voltage or current changes of an opposing polarity to charge or discharge the transfer capacitor and thereby maintain charge balance relative to cable capacitances of cables connecting the high voltage power source to the tool. The system can be used with electron beam tools such as scanning electron microscopes, electron beam inspection tools, or electron lithography tools.