Liquid flow rate estimation and verification by direct liquid measurement
First Claim
1. A method for calibrating a liquid flow controller, comprising the steps of:
- measuring an expected elapsed time for draining a mass of liquid through an inlet line connected to an inlet of a pre-calibrated liquid flow controller at an expected flow rate;
measuring an actual elapsed time for draining said mass of liquid through said inlet line connected to an inlet of a liquid flow controller set at said expected flow rate;
computing calibration information using said expected elapsed time and said actual elapsed time; and
calibrating said liquid flow controller using said calibration information to achieve said expected flow rate of said liquid.
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Abstract
An apparatus for controlling the flow of a liquid precursor into a deposition chamber comprises a liquid injection system having a liquid injection outlet connected to a chamber inlet line upstream of the deposition chamber. The liquid injection system includes a liquid precursor supply, a purge gas supply, a carrier gas supply, a liquid flow meter, and a controller managing flows of the liquid precursor and carrier gas to the chamber. A purge line is connected between the purge gas supply and the liquid flow meter and is used to trap a known mass of liquid precursor. To calibrate the flow of the liquid precursor, the purge gas is used to push the trapped liquid precursor through the liquid flow meter at a steady rate. The elapsed time for evacuating the trapped liquid precursor from the purge line is measured. Calibration information is computed using the mass of the trapped liquid precursor and the measured elapsed time based on the direct liquid measurement approach. The calibration information is used to calibrate the controller to correct deviations in the liquid flow rate and achieve a target liquid precursor flow rate for improving wafer uniformity.
418 Citations
24 Claims
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1. A method for calibrating a liquid flow controller, comprising the steps of:
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measuring an expected elapsed time for draining a mass of liquid through an inlet line connected to an inlet of a pre-calibrated liquid flow controller at an expected flow rate; measuring an actual elapsed time for draining said mass of liquid through said inlet line connected to an inlet of a liquid flow controller set at said expected flow rate; computing calibration information using said expected elapsed time and said actual elapsed time; and calibrating said liquid flow controller using said calibration information to achieve said expected flow rate of said liquid. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for calibrating a liquid flow meter in a precursor liquid injection system, said method comprising the steps of:
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trapping a liquid precursor with a mass in a tube having an outlet connected to an inlet of a liquid flow meter; supplying a purge gas to an inlet of said tube, said purge gas and said liquid precursor forming a liquid-gas boundary therebetween; setting said liquid flow meter at an expected liquid precursor mass flow rate to release said trapped liquid precursor from said tube to flow through said inlet of said liquid flow meter with said liquid-gas boundary moving across said tube; measuring an elapsed time for said liquid-gas boundary to reach said inlet of said liquid flow meter; computing calibration information using said elapsed time; and calibrating said liquid flow meter using said calibration information. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A method for controlling the flow of a liquid precursor into a deposition process chamber, said method comprising the steps of:
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accumulating a liquid precursor in a line connected upstream to a liquid precursor controller; directing a purge gas at a start time t0 to drive said liquid precursor from said line through said liquid precursor controller at a liquid precursor flow rate, said liquid precursor drained from said line at an end time t1 ; generating control data from said start time and said end time; and controlling said liquid precursor flow rate to achieve an intended liquid precursor flow rate in response to said control data. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification