Czochralski n-type Si(100) wafers were implanted at room temperature with 160keV He ions to a fluence of 5 x 1016/cm2 and with110keV H ions to a fluence of 1016/cm2, singly or in combination. Surface phenomena and defect microstructures were studied by using techniques including scanning electron microscopy, atomic force microscopy and cross-sectional transmission electron microscopy. Surface exfoliation and flaking phenomena were observed on Si only upon successive implantation of He and H ions following subsequent annealing at temperatures above 400C. The surface phenomena exhibited a strong dependence upon the thermal budget. At annealing temperatures ranging from 500 to 700C, craters with a size of about 10μm were produced throughout the Si surface. Upon increasing the temperature to 800C, most of the implanted layer was sheared, leaving structures like islands on the surface. Atomic force microscopic observations demonstrated that the implanted layer was transfered mainly at a depth of around 960nm; which was quite consistent with the range of the ions. XTEM observations revealed that additional low-fluence H ion implantation could significantly influence the thermal growth of He-cavities, which gave rise to a monolayer of cavities surrounded by a large amount of dislocations and strain.

Surface Exfoliation and Defect Structures in Si Induced by 160keV He and 110keV H Ion Implantation. Z.Wang, C.Liu, T.Liu, X.Zhang, W.Li, W.Li, B.Yuan, P.Wu, M.Li: Nuclear Instruments and Methods in Physics Research B, 2008, 266[2], 250-5