Boron doping of silicon by excimer laser irradiation in a reactive atmosphere - The incorporation mechanism

UV excimer lasers have been used to dope semiconductors by a one-step process in which the laser serves both to melt a controlled thickness of a sample placed in dopant ambient and to photodissociate the dopant molecules themselves. Here we report the boron doping of silicon by means of an ArF (193 nm) excimer laser. Dopant atoms are obtained by photolysis of BCl₃ or pyrolysis of BF₃ molecules. The doping is performed both in gas ambient and using only an adsorbed layer. We have investigated the dependence of doping parameters such as laser pulse repetition and gas pressure on the subsequent boron impurity profiles and the dopant incorporation rate. These results indicate that the laser doping process is dopant-flux limited for BF₃ and externally rate limited for BCl₃.