1. A method of identifying an airborne molecular contamination (AMC) leaking source in a fab, the method comprising: distributing a sensor in the fab; executing a forward computational fluid dynamics (CFD) simulation of an air flow in the fab; setting an inversed modeling of the forward CFD simulation of the air flow in the fab; building up a database of a spatial response probability distribution matrix of the sensor; and identifying an AMC leaking source using AMC measurement data and the database of the spatial response probability distribution matrix of the sensor.