Pressure Control System with Chamber Volume Estimation
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Solution Overview
Problem
Pressure control systems in semiconductor processing face sub-optimal performance due to inaccurate chamber volume input and limited bandwidth of the valve motion controller, leading to longer settling times and oscillatory responses.
Innovation Solution
A pressure control system that includes a pressure sensor, a valve, and a controller capable of estimating the chamber volume and modifying the pump speed curve to maintain a minimum slope, ensuring accurate pressure control by adjusting the valve position based on pressure measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the existing algorithm is used to gather the actual pump speed curve, then the pump speed curve can be obtained, but the slopes near zero require a high bandwidth of the valve motion controller which is limited, resulting in an inadequate and oscillatory response
Solution Approach 1:
The patent modifies the pump speed curve by adjusting its parameters (specifically the slopes) to ensure they meet minimum values. This transforms the original curve with near-zero slopes into a modified curve with adequate slopes, enabling the valve motion controller to operate within its bandwidth limits while maintaining stable pressure control without oscillations
2Ease of operation
If the user enters the chamber volume by hand, then the input is obtained, but the user may not know the accurate value, resulting in compromised pressure control performance with longer settling time and larger overshoot or undershoot
Solution Approach 1:
The system performs self-characterization by automatically estimating the chamber volume through pressure transient analysis during a learn mode operation. Instead of relying on manual user input, the system uses its own pressure measurements and the identified pump speed curve to compute the chamber volume, ensuring accuracy without requiring user expertise
Solution Approach 2:
The patent replaces the manual measurement and input method with an automated computational method. The chamber volume is determined through algorithmic processing of pressure transient data and pump speed curve identification, substituting the mechanical/manual volume measurement approach with a software-based estimation technique
3Reliability
If model-based control algorithms are used to control the valves based on pressure setpoint trajectory, then pressure control performance can be optimized, but various system parameters such as chamber volume and pump speed curve must be known accurately
Solution Approach 1:
The system implements a learn mode that uses feedback from pressure sensor measurements during a characterization phase. The pressure transients are measured and fed back to the controller, which then identifies the pump speed curve and estimates the chamber volume, automatically populating the required system parameters for model-based control
Solution Approach 2:
The patent performs preliminary system characterization during a learn mode before normal operation. The pump speed curve and chamber volume are identified in advance through pressure transient analysis, so that when model-based control is activated, all necessary system parameters are already known and stored, enabling immediate optimized control without requiring complex manual measurement procedures
Data Source
AI summary
A pressure control system for controlling pressure of a fluid in a chamber includes a pressure sensor configured to measure the pressure of the fluid in the chamber, and a valve configured to control the pressure of the fluid in the chamber by regulating flow of the fluid from the chamber. The pressure control system further includes a controller. The controller is configured to estimate the volume of the chamber, and to generate a pump speed curve of the valve. The controller is further configured to monitor and modify the pump speed curve so as to maintain a slope of the pump speed curve to at least a minimum value, and to use the modified pump speed curve to adjust the position of the valve in response to pressure measurements by the pressure sensor, so as to maintain the pressure in the chamber at a desired pressure setpoint.