Positive displacement type liquid-delivery apparatus

A deposition apparatus comprising:

• a positive displacement liquid-delivery apparatus comprising:
• a positive displacement pump including a housing having a liquid-delivery chamber and a working space divided from said liquid-delivery chamber by a flexible diaphragm, and including a diaphragm driving unit linked to said diaphragm to discharge fluid from said liquid-delivery chamber by changing a volume of said liquid-delivery chamber;
• and
• a differential pressure control unit for controlling a differential pressure between said liquid-delivery chamber and said working space so as to maintain the differential pressure between said liquid-delivery chamber and said working space at a constant value during a pumping operation of said positive displacement pump;
• a vaporizer for vaporizing the fluid discharged from said positive displacement liquid-delivery apparatus;
• and
• a deposition chamber in which thin films are deposited using the feed gas supplied from said vaporizer;
• wherein said diaphragm driving unit of said positive displacement liquid-delivery apparatus is operable to change the volume of said liquid-delivery chamber while said differential pressure control unit maintains the differential pressure between said liquid-delivery chamber and said working space at the constant value.