Conformality of remote plasma-enhanced atomic layer deposition processes: An experimental study

In total, five metal oxide and one metal plasma-enhanced atomic layer deposition (PEALD) processes were studied with respect to the conformality of the coatings. The study reveals that also high aspect ratio structures (up to 60:1) can be coated conformally with remote PEALD. Oxides could relatively easily be deposited into demanding 3D structures with rather short cycle times but not the silver metal. The key factor in achieving excellent conformality seems to be that sufficient radical density is required to overcome the loss of radicals by recombination. In the case of metals where hydrogen plasma is applied the recombination of hydrogen radicals causes major difficulties in obtaining perfect conformality.