Process Chamber Pressure Control via Predicted Outflow Rate
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Solution Overview
Problem
Existing pressure control methods for process chambers in semiconductor devices require ongoing monitoring and modification of pump speed curves, are labor-intensive, and fail to accurately account for changes in pressure within the vacuum pump, leading to inefficient regulation of gas pressure.
Innovation Solution
A method and device that calculate the predicted outflow rate of gas from the process chamber based on the current pressure within the suction pump and known characteristic suction rate, using a correction value to account for changes in conductance and pressure, allowing for precise control of the inflow rate to maintain a target pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ongoing monitoring and modification of pump speed curves is performed to maintain pressure control, then pressure regulation accuracy is improved, but system complexity and operational time increase
Solution Approach 1:
The patent pre-calculates and stores pump speed curves for various pressure setpoints before operation. During actual pressure control, the system simply selects and applies the appropriate pre-calculated curve based on the target pressure, eliminating the need for real-time monitoring and modification of pump speed curves while maintaining accurate pressure regulation.
2Measurement precision
If pump speed curves are learned and stored for each combination of process chamber and vacuum pump, then pressure control accuracy is improved, but setup time and labor requirements increase
Solution Approach 1:
The patent creates a universal pump speed curve database that can be applied across different combinations of process chambers and vacuum pumps. By establishing general correlation formulas between pressure setpoints and pump speed curves that are independent of specific hardware combinations, the system eliminates the need to perform time-consuming learning procedures for each new chamber-pump configuration.
3Measurement precision
If pressure of gas within the vacuum pump is taken into account for accurate outflow rate calculation, then pressure control precision is improved, but measurement complexity increases
Solution Approach 1:
The patent introduces an intermediary approach by using the relationship between process chamber pressure and vacuum pump pressure through the pump's characteristic suction rate curve. Instead of directly measuring vacuum pump pressure, the system calculates the outflow rate based on the measurable process chamber pressure and the known pump characteristics, thereby achieving accurate pressure control without direct measurement of difficult-to-access parameters.
Data Source
AI summary
A gas pressure within a treatment chamber 2 can be more accurately regulated to a predicted target pressure whereby there can be provided a pressure control apparatus which can easily and speedily regulate the gas pressure for various combination of the treatment chamber 2, a sanction chamber 3 and a valve 4. A required inflow rate (Qi) at which it is necessary for gas to flow into the treatment chamber 2 in order to reach a preset target pressure (Psp) within the treatment chamber is calculated on the basis of the expression of Qi=Qo+(P/□t)V and the thus calculated required inflow rate (Qi) is flown into the treatment chamber 2 to control the pressure within the treatment chamber 2 to the required pressure (Psp). In calculation of a current predicted outflow rate (Qo(n)) at which gas is discharged from the treatment chamber on the basis of the expression Qo(n)=P2*f1(P2), using a current pressure (P2) within the suction pump and a known characteristic suction rate (Sp=f1(P2)) of the suction pump under prescribed pressure, the current pressure (P2) within the suction pump is calculated according to the expression P2=P1−(Qo(n−1)/f2(θ, P)) from an accurate conductance (Cv(θ, P)=f2(θ, P)) calculated by adding the error between the current pressure (P1) actually measured within the treatment chamber and a known specified pressure (P) within the treatment chamber at the characteristic conductance (Cv=f2(θ)) of the valve at the opening/closing angle (θ) associated with the current position of the switching plate of the valve to the known characteristic conductance (Cv=f2(θ)) of the valve at the opening/closing angle (θ) associated with the current position of the switching plate of the valve, and the current predicted outflow rate Qo(n) at which gas is discharged from the treatment chamber is calculated.