Gas supply apparatus

A gas supply apparatus comprising:

• a mount for mounting a substrate to be processed;
• a gas ejector above said mount, said gas ejector including a processing chamber that extends at least partially along said mount;
• and
• an exhaust port between said processing chamber and said mount, wherein
• said gas ejector includes:
• a primary accommodating chamber which temporarily accommodates gas supplied from a gas supply port;
• and
• a nozzle portion between said primary accommodating chamber and said processing chamber, wherein the nozzle portion supplies gas through said processing chamber to said substrate to be processed;
• said nozzle portion has:
• a first restricting cylinder in an uppermost portion of said nozzle portion, the first restricting cylinder having a first opening having a circular cross-sectional shape with a first diameter in plan view, and which supplies the gas in said primary accommodating chamber downward;
• a second restricting cylinder being continuously formed with said first restricting cylinder, the second restricting cylinder having a second opening having a circular cross-sectional shape with a second diameter in plan view, and which supplies the gas supplied from said first restricting cylinder to said processing chamber;
• and
• a third restricting cylinder in a lowermost portion of said nozzle portion and being continuously formed with said second restricting cylinder, the third restricting cylinder having a third opening having a circular cross-sectional shape with a third diameter in plan view, and which supplies the gas supplied from said second restricting cylinder to said processing chamber,
• said gas ejector has only one said nozzle portion,
• said first diameter is set such that pressure difference between said primary accommodating chamber and said processing chamber is not less than 30 times,
• said second diameter is longer than said first diameter,
• said third diameter is longer than said second diameter,
• said first diameter of said first restricting cylinder is not greater than 2 mm in diameter and a formation length of said first restricting cylinder is not greater than 2 mm,
• said first diameter is constant along a height direction in said first restricting cylinder, said second diameter is constant along the height direction in said second restricting cylinder, said third diameter is constant along the height direction in said third restricting cylinder, and
• said nozzle portion has only one of said first restricting cylinder, one of said second restricting cylinder and one of said third restricting cylinder.