A study on the removal of silicon native oxide for ULSI devices

In the UV-excited F-2-H-2 dry cleaning, the etching mechanism and selective etching of silicon native oxide were investigated using PSG, BSG, TEOS and thermal oxide film on silicon wafers. It was discovered that UV-excited F- 2+H-2 treatment leads to relatively lower surface roughness than UV/F-2 tre atment. Besides, the surface roughness after UV-excited F-2+H-2 treatment w as smiliar with after HF wet cleaning. And we found the critical point of s elective etching for silicon native oxide in contact holes from the etching effect of various oxide films above with PR line/spacing pattern. As a res ult, the removal of silicon native oxide in contact holes after UV-excited F-2+H-2 dry cleaning was defined by confirming reduction of Kelvin resistan ce. We confirmed lower Kelvin resistance after UV-excited F-2+H-2 treatment than rather after conventional HF wet cleaning.