Atmospheric Plasma Processing of Undoped and p-Silicon (100) for Thin Oxide Films

The growth of very thin oxide layers on p-doped and undoped Si was explored using atmospheric plasma processing (APP) with ionized air at room temperature and at 150^oC. The number of passes were varied with plasma jet power, scan speed and gas flow rate held constant. Sample surfaces were characterized by measuring the water drop contact angle (CA) with a tensiometer and oxide thickness with an ellipsometer. X-ray photoelectron spectroscopy determined elemental makeup of the oxide layer. After APP with ionized air at room temperature the oxide thickness for undoped samples increased up to 325+/-17Å from the as received value of 18.4+/-0.8Å for 5 passes. Oxide thickness after APP for heated undoped samples increased with number of passes attaining a maximum of 80+/-4.4Å at 9 passes. Similar trends were noted for doped substrates although oxide layers were thinner. CAs for APP treated samples decreased immediately after treatment, but increased over time. The distribution in CA values for was higher at 150^oC for both substrates indicating greater non-uniformity of sample surfaces when temperature is increased. APP with nitrogen plasma had considerably less impact on oxide thickness and CA measurements compared to ionized air plasma.