NOVELTY - The process of cleaning a surface of a silicon substrate covered with silicon oxide layer, comprises exposing the surface to a radiofrequency plasma generated from a fluoride gas in a reaction chamber to produce an etch of the silicon oxide layer and to absorb fluoride elements on the surface, and exposing the surface comprising the fluoride elements to a hydrogen radiofrequency plasma in the chamber for eliminating fluoride elements from the surface. The steps of exposing the surface to the radiofrequency plasma and the hydrogen are carried out for 380 seconds and 30 seconds respectively.    USE - The process is useful for cleaning a surface of a silicon substrate covered with silicon oxide layer, where the silicon substrate is useful for fabricating heterojunction solar cells.    ADVANTAGE - The process is capable of economically cleaning a surface of a silicon substrate covered with silicon oxide layer without using any liquid pollutants and surface defects, and avoids contamination of the substrate by foreign pollutants.    DETAILED DESCRIPTION - The process of cleaning a surface of a silicon substrate covered with silicon oxide layer, comprises exposing the surface to a radiofrequency plasma generated from a fluoride gas in a reaction chamber to produce an etch of the silicon oxide layer and to absorb fluoride elements on the surface, and exposing the surface comprising the fluoride elements to a hydrogen radiofrequency plasma in the chamber for eliminating fluoride elements from the surface. The steps of exposing the surface to the radiofrequency plasma and the hydrogen are carried out for 380 seconds and 30 seconds respectively. The power density generated with the plasma is 10-350 mW/cm2. The pressure of the fluoride gas and hydrogen in the reaction chamber is 10-200 mTorr and 500 mTorr respectively, and the temperature of the silicon substrate is 150 degrees C. The voltage of the radiofrequency plasma is 10 W. The silicon fluoride gas is silicon tetrafluoride, which has a pressure of 30 mTorr. The chamber is plasma enhanced chemical vapor deposition chamber.