A low defect rate is provided in rapid thermal processing of delicate components with reduction of defects caused by inhomogeneities of temperature during a rapid thermal processing. In a suitable system a defect-guarded RTP method is carried out in such a manner that the density of the heating energy is adjusted in consecutive intervals of time, which may be as short as desired, to such automatically controlled limiting values or to such fixed values that in the reaction chamber the difference between the primary and secondary energy densities is almost continuously held at the minimum which is achievable throughout the thermal processing whereas the ramps have predetermined slopes.