Dual Controller Ozone System for Multi-Chamber Tools
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Solution Overview
Problem
Conventional ozone delivery systems for multi-chamber semiconductor processing tools face challenges in maintaining a consistent ozone concentration during chamber activation or deactivation, leading to compromised semiconductor product quality due to slow reaction times and increased equipment costs.
Innovation Solution
A system comprising an ozone generator, flow sensor, and dual controllers that quickly adjust ozone production based on detected events, using a predictive control algorithm and look-up table to maintain desired concentrations across multiple chambers, reducing settling time and capital equipment costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single ozone generator is used to service multiple chambers, then equipment cost is reduced, but concentration control accuracy deteriorates due to slow response time
Solution Approach 1:
The system pre-calculates and stores the relationship between flow rates and required power settings in a look-up table before operation. When a chamber event occurs, the controller immediately retrieves the pre-determined power setting from the look-up table corresponding to the new total flow rate, eliminating the need for slow real-time iterative calculations and achieving rapid concentration control with a single ozone generator.
2Device complexity
If conventional PID control is used, then system simplicity is maintained, but response time increases to 30 seconds or greater
Solution Approach 1:
The look-up table contains pre-computed power settings for various flow rate conditions. When a chamber is activated or deactivated, the controller calculates the new total flow rate, queries the look-up table for the corresponding optimal power setting, and immediately adjusts the ozone generator power accordingly. This pre-computation approach reduces the response time from 30 seconds or greater to a matter of seconds, while keeping the control system relatively simple.
3Stability of the object's composition
If ozone generator power is adjusted rapidly during chamber events, then concentration stability is improved, but ozone production variability increases
Solution Approach 1:
The system incorporates concentration sensors in each chamber that continuously monitor the actual ozone concentration and provide feedback to the controller. The controller compares the measured concentration with the desired setpoint and dynamically adjusts the ozone generator power to maintain concentration stability. This closed-loop feedback control ensures that despite rapid power adjustments during chamber events, the ozone concentration remains stable and within specifications, while minimizing unnecessary ozone production variability.
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 ensures rapid and accurate ozone concentration control, minimizing semiconductor product defects and reducing ozone consumption, while eliminating the need for dedicated ozone generators per chamber, thereby enhancing productivity and quality.
Implementation Method 1
Some ozone generators require the use of inert dopant gases, such as for example, nitrogen or carbon dioxide, to increase the ozone concentration to acceptable levels
Implementation Method 2
The flow sensor of the system is used to measure a total flow rate through the plurality of processing chambers
Implementation Method 3
The concentration sensor is used to measure a concentration level of ozone in the gas output of the ozone generator
Implementation Method 4
Ozone is particularly useful for removing hydrocarbons from the surface of semiconductor wafers or from processing chambers
Data Source
AI summary
An improved system and method for controlling ozone concentration in connection with a multi-chamber tool. The system and method involve a first and a second concentration controller in combination with an ozone generator. The first concentration controller detects an EVENT (i.e., one of the chambers in the multi-chamber tool coming on-line or off-line) and in response provides a power instruction to the ozone generator in accordance with a predictive control algorithm. The first concentration controller has a fast (i.e, about 1 second) response time. The second concentration controller is masked from the ozone generator during the EVENT, but otherwise controls the generator after an interval of time has lapsed after the EVENT. The second concentration controller has a slower response time than the first concentration controller, however the second concentration controller provides the system with long-term stability and can be used to provide updated data to the predictive control algorithm.