Ion-cutting of Si onto glass by pulsed and direct-current plasma immersion ion implantation

Ion-cutting using plasma immersion ion implantation (PIII) was investigated for the integration of single crystalline Si layers on glass. In PIII, the sample is immersed in a plasma consisting of the ions of interest. A dc (direct current) or ac (alternating current) voltage is then applied to the sample to extract ions from the plasma and implant into the sample. PIII is inherently more efficient for high dose implantation. It was found that p-Si wafers implanted nominally at room temperature with H doses on the order of a few times 1016 cm−2 could be readily bonded to glass substrates with proper surface treatment similar to that used in conventional implantation for ion-cutting. The wafer surface of the as-implanted Si was converted from p-type to n-type. Upon bonding at room temperature, annealing (300 °C), and exfoliation (450 °C), the transferred Si layer on glass and the as-exfoliated surface of the implanted Si wafer remained n-type. Transmission electron microscopic examination showed a highly defective region near the top of the Si layer transferred onto glass due to H implantation. However, the crystalline quality was nearly defect-free in the deeper region of the layer, in spite of the incorporation of other impurities in the region. Annealing at sequentially higher temperatures led to the recovery of p-type conductivity at ∼600–650 °C. The thickness of the transferred layers suggested that the implanted species were mostly H3+ ions from the PIII implanter used in this study. Secondary ion mass spectrometry results showed coimplanted atmospheric impurities such as oxygen, nitrogen, and carbon that affected the electrical properties of the transferred Si layers. dc PIII is demonstrated in this study to be more superior than conventional pulsed PIII for this process and improved vacuum conditions of the implantation chamber are needed to eliminate or reduce impurities.