3.5.1 Background

The original investigations of IBS referred to in Section 3.1, which culminated in the successful development of SIMOX and related technologies, were initiated during the 1950s and 1960s, long before the development of modern high current ion implanters. It is ironic that high current mass separators were also not available at that time as, during the 1940s in a different context, a technology (Calutrons) had been developed to generate and transport high current U ⁺ ion beams to produce ²³⁵U enriched uranium for the World War II Manhattan Project [96]. Consequently the original IBS experiments were carried out on home made implanters with low beam currents typically of order 10 A. The high doses, in the range 10 ¹⁷ O ⁺ cm ^?2 to 10 ¹⁸ O ⁺ cm ^?2, could only be achieved by reducing the implanted area to one or, at best, a few cm ² and accepting long implantation times of many hours or even days. Fortunately this could be justified in the academic research environment where many of the experiments were carried out.

Early experiments soon highlighted the importance of dynamic annealing during the O ⁺ implantation but, in the absence of heated chucks upon which to mount the wafers, the power (P = IV) carried by the ion beam was used to heat the target and achieve the desired annealing temperature [89]. This is possible because a silicon...