Method for using ultra-thin etch stop layers in selective atomic layer etching

A substrate processing method, comprising:

• providing a substrate containing a first film on a substrate and a second film on the first film;
• initiating etching of the second film using a thermal atomic layer etching (ALE) process that selectively etches the second film relative to the first film;
• removing the second film using the ALE process, wherein the etching self-terminates at an interface of the second film and the first film;
• and
• following the removing, etching the first film using an additional ALE process, wherein the ALE process includes alternating gaseous exposures of a first reactant and a second reactant, and the additional ALE process includes alternating gaseous exposures of the first reactant and a third reactant that is different than the second reactant, and wherein the ALE process and the additional ALE process are performed without plasma excitation of the first reactant, the second reactant, and the third reactant.

A substrate processing method, comprising:

• depositing a ZrO2 film on a substrate;
• depositing a Al2O3 film on the ZrO2 film;
• initiating etching of the Al2O3 film using a thermal atomic layer etching (ALE) process that selectively etches the Al2O3 film relative to the ZrO2 film;
• and
• removing the Al2O3 film using the thermal ALE process, wherein the etching self-terminates at an interface of the Al2O3 film and the ZrO2 film.