Filter apparatus for semiconductor device fabrication process

A liquid supplying system comprising:

• a semiconductor wafer processing apparatus;
• a liquid tank configured to store a liquid for manufacturing a semiconductor device;
• a liquid supply system for supplying the liquid from the liquid tank to the semiconductor wafer processing apparatus;
• and
• a point-of-use (POU) filter device disposed on the liquid supply system,
• wherein the POU filter device includes:
• one or more filter membranes;
• and
• a filter housing enclosing the one or more filter membranes,
• each of the filter membranes includes a base membrane made of anodic aluminum oxide, and a plurality of through holes,
• the base membrane is coated with a coating material,
• an average diameter of the plurality of through holes is in a range from 10 nm to 500 nm, and
• a variation of diameters of the plurality of through holes is in a range from 5% to 25% of the average diameter.

A method of cleaning a filter device, comprising:

• determining whether the filter device is to be cleaned or not;
• and
• after determining that the filter device is to be cleaned, flowing a cleaning solution through the filter device in a reverse direction,
• wherein the filter device includes:
• a filter membrane;
• and
• a filter housing enclosing the filter membrane,
• the filter membrane includes a base membrane made of anodic aluminum oxide, and a plurality of through holes,
• the base membrane is coated with a coating material,
• an average diameter of the plurality of through holes is in a range from 10 nm to 500 nm, and
• a variation of diameters of the plurality of through holes is in a range from 5% to 25% of the average diameter.