Laser direct writing and doping of single-crystal silicon using liquid silanes

Abstract Laser direct writing is a highly promising method for material fabrication due to its simplicity, design flexibility, and ability to create complex structures that are difficult to achieve with conventional etching techniques. However, despite these advantages, it is currently not suitable for the growth of monocrystalline silicon, a key material in microelectronics with significant production value. This limitation arises from the use of low-order silane molecules or solid silicon particles in conventional laser direct writing processes. These feedstocks require high decomposition or melting energies and exhibit complex crystallization behavior during growth. As a result, the process typically yields only polycrystalline or amorphous silicon, thereby hindering its ability to meet the stringent performance requirements of highperformance electronic devices. In this study, laser direct writing of monocrystalline silicon was successfully achieved using an unconventional high-order liquid silane feedstock with high reactivity at low temperatures. A systematic comparison was conducted to evaluate the performance differences between low-order and high-order liquid silanes in the laser direct writing of monocrystalline silicon. The results indicate that the high-order liquid silane, cyclohexasilane (CHS), offers significant advantages in terms of silicon growth rate and the laser energy threshold required for growth. Furthermore, by dissolving white phosphorus in CHS, this study successfully achieved efficient in-situ doping of monocrystalline silicon. This approach not only avoids the use of highly toxic phosphorus sources (e.g., PH3) but also simplifies the doping process, offering a new strategy for low-damage, high-precision doping in semiconductor device fabrication. Overall, this study highlights the processing advantages of CHS in silicon-based micro- and nanofabrication and provides a valuable reference for new semiconductor manufacturing technologies.