Ventilation system and method of using

A ventilation system for preventing contamination in a load lock chamber having a movable wafer holding device, the ventilation system comprising:

• a ventilation hood body, the body having an open bottom portion, the bottom portion having a bottom peripheral edge, wherein the bottom peripheral edge has an O-ring adapted to sealingly engage the wafer holding device,
• a top portion, the top portion forming an airtight horizontally disposed top chamber, and
• a middle portion vertically juxtaposed between the top portion and the bottom portion, the middle portion further having an airtight outer side chamber, wherein the top portion, the middle portion, and the open bottom are in fluid communication with each other and cooperate to define a hood interior, the interior forming a sealed inner chamber when the open bottom portion sealingly engages a wafer holding device;
• a gas supply conduit attached to outer side chamber for supplying a purge gas from a gas supply source through the enclosed outer side chamber and into the interior of the hood body;
• an exhaust system connected to the top chamber of the hood body for removing the purge gas from the sealed chamber;
• and
• means for evenly distributing a purge gas through the hood body, wherein the means for evenly distributing a purge gas through the hood body evenly distributes flow of the purge gas through the hood interior, the distributing means having a plurality of distribution holes disposed in an airtight manner within the top chamber and within the middle portion side chamber.

A method for using a ventilation system to eliminate load lock contamination particles within a load-lock chamber comprising the steps of:

• providing a load-lock chamber in communication with a processing chamber, the load lock chamber having a movable wafer holding member capable of moving between a first retracted position for loading and unloading wafers to a second extended position for ventilating outgassing from wafers;
• providing a ventilation hood having a hood body equipped with
• an open bottom portion having a peripheral edge adapted to sealingly engage the wafer holding member, wherein the open bottom portion is positioned above the wafer holding member,
• a top portion forming an upper chamber, the upper chamber having
• an exterior upper wall, the exterior upper wall has an outlet in communication with an exhaust tube for communicating a purge gas from the hood to the atmosphere or to a facility exhaust vacuum, and
• an inner lower wall spaced downwardly apart from the exterior upper wall, the inner lower wall having a plurality of distribution holes disposed therewithin,
• a middle portion having an outer side chamber, the outer side chamber having
• an exterior side wall,
• an inner side wall spaced inwardly apart from the exterior side wall, the inner side wall having a plurality of distribution holes disposed therewithin, and
• an inlet in fluid communication with a gas supply conduit for communicating a purge gas from a gas supply source to an interior of the hood;
• loading a wafer cassette holding a plurality of wafers onto the wafer holding member;
• performing a processing operation on the plurality of wafers disposed within the load lock chamber;
• moving the wafer holding device to the second extended position to sealingly engage a lower peripheral edge of the hood body open bottom;
• flowing a purge gas from the gas supply through the inlet of the outer side chamber, then through the inner side wall distribution holes to the plurality of wafers disposed within the hood interior;
• and
• purging an effluent formed from the purge gas and outgassing of chemicals disposed on the plurality of wafers by exhausting the effluent through the outlet of the top chamber to the exhaust tube in communication with the exhaust system.