Comparison of thermally and mechanically induced Si layer transfer in hydrogen-implanted Si wafers

Hydrogen ion-implantation into Si and subsequent heat treatment has been shown to be an effective means of cleaving thin layer of Si from its parent wafer. This process has been called Smart Cut^TM or ion-cut. We investigated the cleavage process in H-implanted silicon samples, in which the ion-cut was provoked thermally and mechanically, respectively. A 〈1 0 0〉 oriented p-type silicon wafer was irradiated at room temperature with 100 keV H₂⁺-ions to a dose of 5 × 10¹⁶ H₂/cm² and subsequently joined to a handle wafer. Ion-cutting was achieved by two different methods: (1) thermally by annealing to 350 °C and (2) mechanically by insertion of a razor blade sidewise into the bonded wafers near the bond interface. The H-concentration and the crystal damage depth profiles before and after the ion-cut were investigated through the combined use of elastic recoil detection analysis and Rutherford backscattering spectroscopy (RBS). The location at which the ion-cut occurred was determined by RBS in channeling mode and cross-section transmission electron spectroscopy. The ion-cut depth was found to be independent on the cutting method. The gained knowledge was correlated to the depth distribution of the H-platelet density in the as-implanted sample, which contains two separate peaks in the implantation zone. The obtained results suggest that the ion-cut location coincides with the depth of the H-platelet density peak located at a larger depth.