Radiation emission from ion implanters when implanting hydrogen and deuterium

An increasing interest in proton and deuterium implants has been expressed among the semiconductor device fabricators. The possible production of neutrons and high energy gamma rays during such implants necessitated an extensive radiation study of implanters. A series of experiments to study neutron and gamma production with beams of H, D, B, P and As on common implanter materials such as C, Al, Si and the dopants themselves have been performed. Based on our experimental data, and the underlying physical reactions, we concluded that neutron generation is negligible in operation of B from BF₃ feed materials and from P or As from hydride feed materials. Operation of the implanter with feed materials composed of enhanced amounts of deuterium at any energy will result in significant neutron generation. Proton beams below certain energies can be used safely, with common implanter materials as targets, while maintaining acceptable radiation levels. At higher energies the risk of activation and gamma ray production increases, depending on the material used for the target and beam line components