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In this paper, we report the systematic investigation on the melt characteristics of silicon during laser thermal processing (LTP) of amorphous silicon (a-Si) gates on ultrathin gate oxides. LTP is used to reduce the gate depletion effect in advanced semiconductor devices. The influence of implantation-induced damage and chemical inhomogeneities on the melt behavior of ion-implanted a-Si is studied using in situ time-resolved reflectance (TRR) measurements and ex situ secondary ion mass spectrometry. The results from TRR measurements indicate the presence of a buried melt for a-Si implanted with B+ at a subamorphizing dose. In contrast, such a melt behavior is not observed during LTP of undoped a-Si and a-Si implanted with As+ at an amorphizing dose. We attribute the marked difference in the melt characteristics to the competitive effects between compositional inhomogeneities and the extent of amorphization in the a-Si layer. It should be noted that the as-deposited a-Si gate is not really “amorphous” in the sense of an ion beam-induced amorphous layer. This postulation is verified by the absence of a buried melt in a-Si films implanted with Si+ prior to B+ implantation, where the dose of the Si+ implant is sufficient to cause amorphization in silicon and the amorphization depth greatly exceeds the projected range of the boron implant. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In this letter, the authors study the importance of a low temperature anneal in the removal of crystalline defects resulting from pulsed laser annealing of preamorphized ultrashallow p+/n junction. Using an additional low thermal budget rapid thermal annealing at 600 °C for 60 s, suppression of junction leakage current of two orders in a single-pulse laser annealing and one order in a ten-pulse laser annealing is achieved through a reduction of the residual crystalline defects that could not be annihilated by laser annealing. p-channel metal-oxide-semiconductor field effect transistors with good electrical characteristics can be obtained using pulsed laser annealing followed by a low thermal budget rapid thermal annealing. [ABSTRACT FROM AUTHOR]