System and method for detecting remaining amount of precursor in vessel during CVD process

A system for detecting the remaining amount of a precursor in a vessel during a CVD process, the system comprising:

• a bombe for containing carrier gas;
• a first pipe whose one end is connected to the bombe such that the carrier gas can flow through the first pipe;
• a vessel for containing a liquid precursor, to which the other end of the first pipe is so connected as to be submerged in the precursor such that the precursor can be bubbled and vaporized by the carrier gas;
• a second pipe whose one end is connected to the vessel in such a way as to be placed above the liquid surface of the precursor such that the precursor and the carrier gas can be transported through the second pipe;
• a reactor to which the other end of the second pipe is connected and in which a chemical vapor deposition process is performed on a wafer disposed therein with the precursor;
• a liquid level detector disposed on the bottom of the vessel such that it transmits an ultrasonic wave and receives the ultrasonic wave reflected from the level surface of the precursor;
• an A/D converter connected to the liquid level detector for converting the analog ultrasonic signals to digital signals;
• and
• a discrimination unit connected to the A/D converter for discriminating whether or not the liquid level of the precursor is relatively low, based on the transmitted/received data.