Method for in-situ liquid flow rate estimation and verification

Claim 1

An apparatus for controlling a vapor deposition process in a deposition chamber to which a vacuum pump is connected, said apparatus comprising: a pressure sensor connected to said chamber, said pressure sensor generating a signal that is indicative of a pressure inside of said chamber; a vaporization device connected to said chamber; a carrier gas flow controller connected between a source of carrier gas and said vaporization device, said carrier gas flow controller controlling a flow of carrier gas into said vaporization device for delivery into said chamber; a liquid mass flow controller connected between a source of liquid precursor and said vaporization device, said liquid mass flow controller controlling a liquid mass flow rate of the liquid precursor into said vaporization device for delivery into said chamber; a programmed control unit receiving the signal from said pressure sensor and controlling the operation of the liquid mass flow controller and the carrier gas flow controller, said programmed control unit programmed to perform the steps of: measuring a steady-state base pressure of the chamber; after measuring said base pressure, causing said carrier gas flow controller to flow carrier gas into said chamber at a preselected rate; with carrier gas flowing into the chamber at the preselected rate, measuring a first steady-state pressure of the chamber; after measuring said first steady-state pressure, sending a first control signal to the liquid mass flow controller, said first control signal controlling a flow of liquid precursor into the vaporization device; with liquid precursor flowing into the vaporization device under control of the first control signal, measuring a second steady-state pressure in said chamber; and computing a calibration constant, C, from the base pressure and the first and second steady-state pressures; and modifying said control signal by said calibration constant.

Claim 2

An apparatus for controlling a vapor deposition process in a deposition chamber to which a vacuum pump is connected, said apparatus comprising: a pressure sensor connected to said chamber, said pressure sensor generating a signal that is indicative of a pressure inside of said chamber; a vaporization device connected to said chamber; a carrier gas flow controller connected between a source of carrier gas and said vaporization device, said carrier gas flow controller controlling a flow of carrier gas into said vaporization device for delivery into said chamber; a liquid mass flow controller connected between a source of liquid precursor and said vaporization device, said liquid mass flow controller controlling a liquid mass flow rate of the liquid precursor into said vaporization device for delivery into said chamber; a programmed control unit receiving the signal from said pressure sensor and controlling the operation of the liquid mass flow controller and the carrier gas flow controller, said programmed control unit programmed to perform the steps of: measuring a steady-state base pressure of the chamber; after measuring said base pressure, causing said carrier gas flow controller to flow carrier gas into said chamber at a preselected rate; with carrier gas flowing into the chamber at the preselected rate, measuring a first steady-state pressure of the chamber; after measuring said first steady-state pressure, sending a first control signal to the liquid mass flow controller, said first control signal controlling a flow of liquid precursor into the vaporization device; with liquid precursor flowing into the vaporization device under control of the first control signal, measuring a second steady-state pressure in said chamber; and computing a calibration constant, C, from the base pressure and the first and second steady-state pressures; and modifying said control signal by said calibration constant.