The delamination of thin silicon layers by ion implantation and annealing has been studied in H+ implanted silicon layers. Hydrogen ions are implanted into a (100) p-silicon layer through a 100 nm thick oxide layer at 100 keV with different doses ranging from 1.0×1016 to 1.0×1017 ion/cm2. Delamination of thin silicon layers was clearly observed in cross-sectional scanning electron microscope photographs at doses above 5.0 × 1016 ion/cm2. The delamination occurs at 485°C with 10 min annealing for an implantation at 5.0 × 1016 ion/cm2. This temperature, however, can be reduced to 425 and 400°C by increasing annealing time to 60 and 120 min, respectively. Delamination is closely related to the formation of H-Si defect bonds and the release of a hydrogen atom from these bonds in the hydrogen ion implanted Si layer. Temperature variation of the intensity in the hydrogen desorption shows two intensity peaks at 450 and 650°C.