Process Chamber Pressure Control via Predicted Outflow Rate Calculation
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Solution Overview
Problem
Existing methods for controlling pressure in semiconductor process chambers require ongoing monitoring and modification of pump speed curves, are labor-intensive, and fail to account for the pressure of gas within the vacuum pump, making them impractical for rapid adaptation to various combinations of process chambers, vacuum pumps, and valves.
Innovation Solution
A method and device that calculate the necessary input flow rate into the process chamber to maintain a preset target pressure by computing the predicted outflow rate and considering the characteristic pumping rate of the vacuum pump and conductance of the valve, allowing for accurate and rapid pressure control across different combinations of equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ongoing monitoring and modification of pump speed curves is performed to maintain pressure at preset values, then pressure control accuracy is improved, but system complexity and labor requirements increase significantly
Solution Approach 1:
The patent pre-calculates and stores pump speed curves for various process chamber volumes before actual operation. This preliminary action eliminates the need for real-time monitoring and modification during production, reducing system complexity while maintaining pressure control accuracy through lookup tables of pre-computed parameters.
Solution Approach 2:
The patent creates simplified representations (copy) of the complex pump speed characteristics by generating lookup tables based on process chamber volume. These copied data structures replace the need for complex real-time calculations and monitoring systems, maintaining accuracy while reducing operational complexity.
2Reliability
If pump speed curves are learned and stored for each combination of process chamber and vacuum pump, then pressure control reliability is improved, but setup time and labor requirements increase
Solution Approach 1:
The patent focuses the learning process on a single critical parameter - process chamber volume - rather than requiring separate curves for every combination of chamber and pump. This localized approach to parameter identification maintains reliability by capturing the essential characteristic while dramatically reducing setup time and complexity.
Solution Approach 2:
The patent creates a universal solution where a single learned parameter (process chamber volume) can be applied across multiple combinations of process chambers and vacuum pumps. This universal approach eliminates the need for separate learning processes for each device combination, reducing setup time while maintaining reliable pressure control.
3Adaptability or versatility
If the system is reset each time combinations of process chamber and vacuum pump change, then adaptability to different configurations is improved, but productivity and operational efficiency decrease
Solution Approach 1:
The patent pre-calculates pump speed curves for a range of process chamber volumes during the learning phase. This preliminary preparation allows the system to quickly adapt to different configurations by selecting from pre-computed curves rather than resetting and re-learning each time, maintaining adaptability while improving operational efficiency.
Solution Approach 2:
The patent implements a dynamic selection mechanism that automatically chooses the appropriate pre-calculated pump speed curve based on the detected process chamber volume. This dynamic adaptation eliminates manual resetting while maintaining configuration versatility, allowing the system to efficiently handle different chamber-pump combinations without productivity loss.
Data Source
AI summary
A predicted outflow rate (Qo) at which gas is discharged from a process chamber 2 via a vacuum pump 3 is computed, and an input flow rate (Qi) is calculated in order to reach a preset target pressure (Psp). The input flow rate (Qi) is calculated, on the basis of the expression Qi=Qo+(ΔP/Δt)V, from a known volume (V) of the process chamber 2 and a pressure change rate (ΔP/Δt) obtained from the current pressure (P1) within the process chamber 2 to reach the target pressure (Psp). A current predicted outflow rate (Qo) is estimated on the basis of the expression Qo(n)=P2*f1(P2), from the current pressure (P2) within the vacuum pump 3 and a known characteristic pumping rate (Sp=f1(P2)) of the vacuum pump 3 under preset pressure.