Recrystallization Of Silicon Films Research Articles

Zone-Melt-Recrystallization of Silicon-On-Insulator Films Using a Dual-Lamp Apparatus

AbstractWe have studied the recrystallization of silicon films using a focused dual-lamp apparatus. By careful measurement and control of the power density profile (and focal-plane location) of the line-image and of the uniformity of the substrate temperature we have achieved recrystallization of SOI films on 4“silicon wafers. By taking advantage of the measured difference in power-density-profiles of an arc lamp and a tungsten lamp in the dual-lamp apparatus we have achieved low temperature-gradient, reduced-stress recrystallization yielding SOI films in which the usual branched pattern of subgrain-boundaries are replaced by individual dislocations. In situ study of the melt- and growth-fronts, was done using a viewing system with a resolution of - 10 ¼m. We have also done studies of stress-relief schemes.

Large Grain Growth of Silicon Films on Low Temperature Glass Substrates

ABSTRACTArgon laser recrystallization of silicon films deposited on low temperature glass substrates offers the potential for development of large scale matrix addressable displays incorporating on-glass line drivers and logic circuitry. In order to achieve this promise, the challenge of containing molten silicon, at 1685 K, in close proximity to a glass substrate (Corning 7059) which has an annealing temperature of 914 K, must be met. We have successfully recrystallized areas of several squared millimeters of 500 nm thick silicon films without cracking on 7059 glass substrates. This was achieved by the incorporation of multiple film layers interposed between the silicon and the glass substrate, which serve to control the thermal gradients which occur during the recrystallization process. Grains in the recrystallized films are typically 10µm wide and several hundred µm long, achieved using a laser spot size of approximately 70 µµµµm diameter and a scan rate of 15 cm/s. Comparable results were obtained for a wide range of laser powers, from 7.5 to 9.2 W.

Recrystallization of silicon film on insulating layers using a laser beam split by a birefringent plate

20-μm-wide, 1-mm-long, single-crystal Si films on SiO2 have been produced using a cw Ar laser beam split by a birefringent quartz plate. The single-scan recrystallized region width has been widened by multiple beam splitting. The resultant single-crystal region obtained by multiple scan from the seed is a 90-μm-wide and 100-μm-long area with rare grain boundaries. This split beam method uses the stable and highly efficient TEM00 mode and needs no prepatterned antireflection layers.

Recrystallization of Silicon Film on Nitride/Oxide Double Insulating Structure by CW Laser Irradiation

Double layer structure of thin nitride on thick oxide is used as an insulating material in order to get a good quality of silicon layer on insulator by laser recrystallization. This structure makes deposited polycrystalline silicon (polysilicon) more resistant to stripping off at high power laser irradiation and results in large grains of silicon layer with random crystal orientations. Laser scanning steps of 20 to 30 µm/step are obtained as optimum values for the largest grain size and smooth surface by investigation of grain growth and surface features. A fully oxide isolated bipolar transistor is fabricated in recrystallized silicon film on the substrate with the double insulating structure, and it shows following characteristics; typical values of hFE, BVCBO, BVCEO, and BVEBO are 29, 73 V, 30 V and 5.2 V, respectively. This is the first demonstration of the bipolar transistor in silicon layer on insulator. Quite similar results in grain sizes after laser irradiation and electrical characteristics of transistors are obtained between two kinds ofpolysilicon by conventional LPCVD furnace and an epitaxial reactor at relatively high temperatures, while original grain sizes of the latter are apparently larger than that of the former.