There are provided methods of fabricating a metal silicate layer on a semiconductor substrate using an atomic layer deposition technique. The methods include performing a metal silicate layer formation cycle at least one time in order to form a metal silicate layer having a desired thickness. The metal silicate layer formation cycle includes an operation of repeatedly performing a metal oxide layer formation cycle K times and an operation of repeatedly performing a silicon oxide layer formation cycle Q times. K and Q are integers ranging from 1 to 10 respectively. The metal oxide layer formation cycle includes the steps of supplying a metal source gas to a reactor containing the substrate, exhausting the metal source gas remaining in a reactor to clean the inside of the reactor, and then supplying an oxide gas into the reactor. The silicon oxide layer formation cycle includes supplying a silicon source gas, exhausting the silicon source gas remaining in the reactor to clean the inside of the reactor, and then supplying an oxide gas into the reactor.