A method of processing a substrate includes: sputtering target material for a first amount of time using a first plasma formed from an inert gas and a first amount of power; determining a first counter, based on a product of a flow rate of the inert gas, the first amount of power, and the first amount of time; sputtering a metal compound material for a second amount of time using a second plasma formed from a process gas comprising a reactive gas and an inert gas and a second amount of power; determining a second counter based on a product of a flow rate of the process gas, the second amount of power, and the second amount of time; determining a third counter; and depositing a metal compound layer onto a predetermined number of substrates, wherein a deposition time for each substrate is adjusted based on the third counter.