Rapid Thermal Crystallization Of LPCVD Amorphous Silicon Films

Abstract

The crystallization of LPCVD a-Si by Rapid Thermal Anneal was investigated. RTA polysilicon films can find application in the fabrication of TFTs for AMLCDs, due to the lower thermal budget associated with fast crystallization at high temperatures. It was found that the grain size of the crystallized films decreases with the temperature, in the range of 700°C to 1100°C, while for higher temperatures the opposite trend is observed. The latter observation was attributed to the high thermal vibration of subcritical clusters, that was assumed responsible for the decline in the nuclei population at high annealing temperatures, combined with the faster crystalline growth rate at high temperatures. RTA silicon films were found to have lower intra-grain defect density, that may result in the improvement of the electrical characteristics of the polysilicon films.

Polycrystalline Silicon Thin-Film Transistors on Flexible Steel Foil Substrates for Complementary-Metal-Oxide-Silicon Technology

“…Because the rate of nucleation has a higher activation energy than the rate of crystal growth [20,21,22], raising the crystallization temperature above 600°C increases the number of nuclei, reduces their size, and reduces the field effect mobility [25]. Somewhere above 850°C the nucleation rate is expected to drop while the growth rate keeps rising [20], so that at still higher temperature the grain size and hence the field effect mobility are expected to rise again [26]. Koster [20] suggested that the grain size starts increasing around 850°C, but Hatalis [26] used rapid thermal annealing to find that the smallest grains are obtained at ~1100°C.…”

“…Somewhere above 850°C the nucleation rate is expected to drop while the growth rate keeps rising [20], so that at still higher temperature the grain size and hence the field effect mobility are expected to rise again [26]. Koster [20] suggested that the grain size starts increasing around 850°C, but Hatalis [26] used rapid thermal annealing to find that the smallest grains are obtained at ~1100°C. We explored crystallization temperatures of up to 950°C.…”

Complementary metal-oxide-semiconductor thin-film transistor circuits from a high-temperature polycrystalline silicon process on steel foil substrates

“…However, above some temperature the rate of nucleation begins to drop because the size of the critical nucleus grows [17]. Somewhere above 850 C the nucleation rate is expected to drop while the growth rate keeps rising [17], so that at still higher temperature the grain size and hence the field effect mobility are expected to rise again [28]. Koster [17] suggested that the grain size starts increasing around 850 C, but Hatalis [28] used rapid thermal annealing to find that the minimum grain is obtained at 1100 C. We explored crystallization temperature up to 950 C.…”

Influence of Polysilicon Deposition Conditions on Advanced 3D NAND

“…What's more, the interfacial or inner defects can be also decreased using high pressure or D 2 /H 2 annealing. 8,13,[16][17][18][19][20][21][22] All aforementioned investigations were performed after the deposition of poly-Si and how the deposition conditions impact the properties of poly-Si in advanced 3D NAND memory is, however, rarely revealed. Actually, the deposition conditions indeed play an important role in modulating the properties of poly-Si and this is exactly the motivation of present work.…”

“…23 Amorphous silicon (α-Si) was formed when the deposition temperature is less than 580°C, and it will crystalize and many grains are generated after annealing at higher temperature. 16,20,21,[24][25][26] α-Si is grown following chemical reaction formula:…”