Flammable gas diluter and method therefore

Patent metadata

Field	Value
Publication number	US-12397269-B2
Application number	US-202118001354-A
Country	US
Kind code	B2
Filing date	Jun 7, 2021
Priority date	Jun 12, 2020
Publication date	Aug 26, 2025
Grant date	Aug 26, 2025

Abstract

A flammable gas diluter includes a dilution vessel having an outer envelope defining a longitudinal flow passage from an inlet to an outlet; at least one air inlet assembly for directing a flow of air into the inlet of the dilution vessel; a flammable gas inlet arrangement located towards an inlet end of the dilution vessel; two gas flow generators configured to pump a flow of air into the air inlet assembly, the two gas flow generators being located upstream of the flammable gas inlet arrangement; and two dampers, each of the dampers being mounted between a corresponding gas flow generator and the dilution vessel. Control circuitry is configured to open a damper during an operational mode of the corresponding gas flow generator and to close the damper when the corresponding gas flow generator is stopped in standby mode.

First claim

The invention claimed is:

1. A flammable gas diluter for diluting a flow of flammable gas to a concentration below the flammability limit of said flammable gas, said diluter comprising:
a dilution vessel comprising an outer envelope defining a longitudinal flow passage from an inlet to an outlet;
at least one air inlet assembly for directing a flow of air into said inlet of said dilution vessel;
a flammable gas inlet arrangement located towards an inlet end of said dilution vessel;
two gas flow generators configured to pump a flow of air into said air inlet assembly, said two gas flow generators being located upstream of said flammable gas inlet arrangement;

wherein
said two gas flow generators are configured to operate as operational and backup gas flow generators, and
two dampers, one damper associated with each of said gas flow generators, each of said dampers being mounted between said corresponding gas flow generator and said dilution vessel, said dampers being configured to obscure a passage between said corresponding gas flow generator and said dilution vessel when closed and to open said passage between said gas flow generator and said dilution vessel when open; and
control circuitry configured to control the opening and closing of said dampers, said control circuitry being configured to open said damper during an operational mode of said corresponding gas flow generator and to close said damper when said corresponding gas flow generator is stopped in standby mode.

2. The flammable gas diluter according to claim 1 , said control circuitry being configured in response to a signal indicating that a currently operational gas flow generator is to be stopped and a gas flow generator currently in standby mode is to be started to:
control said gas flow generator in standby mode to start and after a predetermined delay to:
control said damper associated with said started gas flow generator to open.

3. The flammable gas diluter according to claim 2 , wherein said predetermined delay comprises a time for said gas flow generator in standby mode to attain a rotational speed of at least 70% of a normal operational speed.

4. The flammable gas diluter according to claim 2 , said control circuitry being configured to control said damper associated with said gas flow generator to be stopped to close after said predetermined delay and to control said gas flow generator to stop.

5. The flammable gas diluter according to any one preceding claim 1 , said control circuitry being configured in response to a signal indicating said diluter is to startup to:
control said damper associated with said backup gas flow generator to be open and said damper associated with said operational gas flow generator to be closed and to control said backup gas flow generator to start; and
after a set test time to control said operational gas flow generator to start; and
after a predetermined delay to control said damper associated with said operational gas flow generator to open and said damper associated with said backup gas flow generator to close; and
to control said backup gas flow generator to stop operating.

6. A vacuum pumping system for evacuating at least one vacuum chamber in a semiconductor processing tool, said vacuum pumping system comprising:
a plurality of vacuum pumps for evacuating said at least one vacuum chamber; and
an abatement system for receiving an exhaust from at least one of said at least one vacuum chamber, wherein said abatement system comprises a flammable gas diluter according to claim 1 .

7. The vacuum pumping system according to claim 6 , wherein said semiconductor processing tool comprises an extreme ultraviolet lithography tool and said flammable gas comprises hydrogen.

8. The vacuum pumping system according to claim 6 - or 7 , further comprising a housing for housing said plurality of pumps; and
an air flow duct for receiving air from said housing;
said air flow duct being in fluid communication with said at least one air inlet assembly for supplying said air to said flammable gas diluter, such that air flows through said housing, along said air duct and into said diluter in response to operation of at least one of said gas flow generators.

9. A method of controlling the operation of two gas flow generators for supplying a gas flow to a flammable gas diluter according to claim 1 , said method comprising
controlling a first one of said two gas flow generators currently in standby mode to start, while keeping said damper between said first gas flow generator and said dilution vessel in a closed position;
after a predetermined delay:
controlling said damper associated with said first gas flow generator to open.

10. The method according to claim 9 , said method further comprising: controlling said damper associated with said second gas flow generator to be stopped to close after said predetermined delay; and
controlling said second gas flow generator to stop.

11. The method according to any claim 9 - or 10 , said method comprising in response to a signal indicating said diluter is to startup:
controlling said damper associated with said backup gas flow generator to be open and said damper associated with said operational gas flow generator to be closed;
controlling said backup gas flow generator to start; and
after a set test time controlling said operational gas flow generator to start; and
after a predetermined delay controlling said damper associated with said operational gas flow generator to open;
controlling said damper associated with said backup gas flow generator to close; and
controlling said backup gas flow generator to stop operating.

Assignees

• Edwards Ltd

Inventors

• Greenwood Joanne Rachel

Classifications

• B01F35/2209

  Controlling the mixing process as a whole, i.e. involving a complete monitoring and controlling of the mixing process during the whole mixing cycle · CPC title

• G03F7/70808

  Construction details, e.g. housing, load-lock, seals or windows for passing light in or out of apparatus · CPC title

• B01F25/30

  Injector mixers (mixing by creating vortex flow B01F25/10) · CPC title

• G03F7/70841

  Constructional issues related to vacuum environment, e.g. load-lock chamber · CPC title

• G03F7/00

  Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor (using photoresist structures for special production processes, see the relevant places, e.g. B44C, H10P76/00, H05K) · CPC title