ABSTRACTWe have investigated trap levels in silicon after Thermal Pulse Annealing (TPA). Three different annealing systems consisting of tungsten lamps or a graphite heater have been applied. Trap levels induced in different silicon materials (Cz, FZ, Epi) after TPA have been studied by DLTS and admittance spectroscopy. In boron-doped epitaxial silicon and As+- implanted pn-junctions (Cz grown Si), we have observed a prevalent trap level at concentrations of up to 1015cm−3 (depending on anneal conditions and silicon material). The ionization energy of this trap level is Ev+300meV.The concentration of the 300 meV-level was studied as a function of the annealing temperature and the quench rate. The thermal pre-processing history strongly affects the trap concentration induced by TPA. The 300 meV-level is almost completely removed by a subsequent furnace anneal at TA > 400°CFurther trap levels are created in boron- and aluminum- doped silicon by Ar+ or 30Si+ implantation and TPA. The defect natures are discussed.