| CPC H01L 22/12 (2013.01) [G01N 21/55 (2013.01); H01L 21/32137 (2013.01); H01L 21/67253 (2013.01); H01L 21/68707 (2013.01); H05K 3/068 (2013.01)] | 20 Claims |

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1. A method, comprising:
transferring a wafer from a factory interface through a load lock chamber to a buffer chamber;
transferring the wafer from the buffer chamber to a process chamber;
etching the wafer in the process chamber, to remove a material of the wafer;
after the wafer is etched, performing reflectance measurements to the wafer in the factory interface, the load lock chamber, the buffer chamber, or combination thereof, to identify if the material of the wafer is removed entirely according to a reflectance of the wafer;
protecting a vacuum pump in the load lock chamber by performing a ventilation process on the load lock chamber;
receiving the wafer by the load lock chamber from the factory interface when the load lock chamber has a first temperature;
receiving the wafer by the load lock chamber from the buffer chamber when the load lock chamber has a second temperature higher than the first temperature;
performing a first etching process to a first nitride film on the wafer;
when a second nitride film below the first nitride film is exposed, ceasing the first etching process;
performing a second etching process to the second nitride film on the wafer; and
when a buried copper layer below the second nitride film is exposed, ceasing the second etching process.
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