Method and device for decreasing generation of surface oxide of aluminum nitride

A method for decreasing generation of surface oxide of aluminum nitride of LED substrate, used in a physical vapor deposition (PVD) process, comprising:

• step A, transmitting a substrate to a deposition chamber with a first vacuum environment, and depositing the aluminum nitride on the substrate to form an aluminum nitride coated substrate, wherein the substrate is a sapphire substrate;
• step B, transmitting the aluminum nitride coated substrate to a first cooling chamber with a second vacuum environment, and performing a first stage cooling on the aluminum nitride coated substrate;
• and
• step C, transmitting the aluminum nitride coated substrate that has performed the first stage cooling to a second cooling chamber with a third vacuum environment, and performing a second stage cooling on the aluminum nitride coated substrate for decreasing generation of surface oxide of the aluminum nitride coated substrate;
• wherein a pressure of the second vacuum environment is less than a pressure of the third vacuum environment.