Implementations described herein generally relate to the formation of a silicon and aluminum containing layer. Methods described herein can include positioning a substrate in a process region of a process chamber; delivering a process gas to the process region, the process gas comprising an aluminum-containing gas and a silicon-containing gas; activating a reactant gas comprising a nitrogen-containing gas, a hydrogen containing gas, or combinations thereof; delivering the reactant gas to the process gas to create a deposition gas that deposits a silicon and aluminum containing layer on the substrate; and purging the process region. The above elements can be performed one or more times to deposit an etch stop stack.