A method includes etching a dielectric layer of a substrate to form an opening in the dielectric layer, forming a metal layer extending into the opening, performing an anneal process, so that a bottom portion of the metal layer reacts with a semiconductor region underlying the metal layer to form a source/drain region, performing a plasma treatment process on the substrate using a process gas including hydrogen gas and a nitrogen-containing gas to form a silicon-and-nitrogen-containing layer, and depositing a metallic material on the silicon-and-nitrogen-containing layer.

Described herein is a technique capable of preventing a constituent contained in an aluminum alloy from being vaporized and scattered when the aluminum alloy is used in a process vessel which is heated to a high temperature. According to one aspect thereof, there is provided a technique including a process chamber; a substrate support configured to support a substrate in the process chamber; and a heater configured to heat the substrate supported by the substrate support, wherein the substrate support is made of an aluminum alloy containing magnesium, and a surface of the substrate support is coated by a coating film of aluminum oxide containing magnesium oxide and being substantially free of magnesium.