Control of carrier collection efficiency in n⁺p diode with retrograde well and epitaxial layers

The effect of buried implanted layers against carrier collection has been investigated by ion-beam-induced-current (IBIC) measurement. The IBIC measurement revealed that the retrograde well structure is more effective in suppressing soft errors than are conventional well structures in epitaxial substrates. The collection of charge carriers induced by 1.3 MeV proton microprobe irradiation could be reduced by a buried layer formed at a different boron dose. The carrier collection efficiency of the diode with a twin well (i.e., retrograde well) with a higher dose can be reduced to 50% that of a diode with a twin wells in an epitaxial layer.