Characterization of Ion Implanted Silicon Annealed with a Graphite Radiation Source
A Varian IA-200 isothermal annealer has been used to anneal ion implantation damage and electrically activate dopants in As and B implanted silicon with minimal redistribution of the impurity. The anneal occurs in vacuum using infrared radiation from a resistively heated sheet of graphite. Good quality anneals of /sup 11/B implanted samples have been obtained with minimal boron diffusion. Arsenic implanted wafers have also be annealed with excellent results except for a substantial loss of As which occurs unless the wafer has an SiO/sub 2/ cap. The anneal quality of (100) wafers was independent of dose, however, the anneal quality of the (111) wafers improved with increasing As dose.
Transient annealing of arsenic‐implanted silicon using a graphite strip heater
Transient annealing with a graphite strip heater has been used to accomplish solid‐phase epitaxial recrystallization of amorphous layers produced in Si by implantation of 120‐keV As+ ions. For doses of 5×1014 or 2×1015 cm−2, annealing at 900–1000 °C for 10 s results in electrical activation comparable to that obtained by a conventional furnace anneal at 1000 °C for 30 min, but with negligible dopant redistribution. For a dose of 1×1016 cm−2, activation is slightly less than that of furnace‐annealed samples, but sheet resistance as low as 22 Ω/⧠ has been obtained by annealing at 1200 °C for 10 s. Mesa diodes fabricated on strip‐heater‐annealed samples exhibit good junction characteristics.
Electron‐beam annealing of ion‐implantation damage in integrated‐circuit devices
The use of a large‐diameter pulsed electron beam to anneal ion‐implantation damage has been studied with application to integrated‐circuit structures. The annealing of arsenic‐implanted p‐n junction diodes shows that properly selected exposure to an electron beam can anneal implant damage and provide nearly ideal device characteristics. Tests on MOS capacitor structures show that the electron beam itself introduces states at the Si‐SiO2 interface but that these states can be easily annealed during the low‐temperature metal alloy cycle. The practical utilization of the concept requires an electron beam uniform over the entire wafer area.