Problems with the concept of thermal budget: Experimental demonstrations

Up to now, kinetic effects in rapid thermal processing (RTP) have been assessed using the concept of thermal budget, with the idea that thermal budget minimization should minimize dopant diffusion and interface degradation. This work highlights shortcomings with that principle. Experiments comparing directly the rate of Si chemical vapor deposition with that of dopant diffusion show how thermal budget minimization can actually worsen diffusion problems rather than mitigate them. We present a straightforward framework for improving the results through comparison of activation energies of the desired and undesired phenomena. This framework explains the experimental results and provides strong kinetic arguments for continued development of rapid isothermal processing and small batch fast ramp methods.