HYDROGEN CLEANING OF SILICON-WAFERS - INVESTIGATION OF THE WAFER SURFACE AFTER PLASMA TREATMENT

A single-step cleaning procedure with a newly developed ultrahigh vacuum (UHV) compatible plasma source is described. Utilizing this source, an argon-hydrogen d.c. discharge between the heated filament (cathode) and the grounded chamber walls (anode) of an UHV system is established. The discharge is characterized by high currents (up to 100 A) and low voltages (20 V-35 V). Without additional wet chemical cleaning steps, the silicon wafer as obtained from the manufacturer is cleaned by exposure to the plasma. The influence of the plasma treatment on the hydrogen content and the perpendicular strain profile of the wafer are investigated by elastic recoil detection, Rutherford backscattering channelling and high resolution X-ray rocking curve diffraction measurements.