Fabrication of hafnium silicate films by plasma-enhanced chemical vapor deposition

According to the guideline of manufacturing processes on the future CMOS technology, the thickness of the gate silicon dioxide is expected to be scaled down to less-than-1 nm in the near future. In this region, silicon dioxide would not maintain the insulating property, since direct tunneling dominates the leakage current. In order to overcome this difficulty, several attempts to increase the physical thickness, while keeping the equivalent silicon dioxide thickness, have been carried out using materials with a higher permittivity. Future gate dielectric materials with a higher permittivity have been requested to possess excellent insulating property, excellent thermal stability at the interface layer with a silicon substrate or electrode, a large band gap with a favorable band structure, and adaptability for semiconductor process technology. We have tried to deposit hafnium silicate films by plasma-enhanced chemical vapor deposition (PECVD), and have successfully obtained good films. In this report, we briefly describe the developed deposition method and discuss electrical properties and chemical structure of the deposited films.