Laser Recrystallization Of Silicon Research Articles

Characterization of the effects of different capping layer structures on the laser recrystallization of silicon by using electrical test structures and Raman spectroscopy

Polycrystalline silicon on insulator is laser-recrystallized using three different capping layer structures on separate wafers. The capping layer structures used include a 6-nm nitride layer, a combination of 64-nm nitride and 20-nm oxide layers, and 50-nm nitride antireflection periodic stripes oriented parallel to the direction of laser scanning. Electrical characteristics are measured by metal-oxide-semiconductor (MOS) silicon-on-insulator (SOI) test structures fabricated in the laser-recrystallized silicon films. Measurement of carrier mobilities, MOS interface properties, leakage currents, and ring oscillator delay times are compared for wafers having different capping layer structures. Stress in each case is characterized using a Raman spectrometer with microprobe.

Effects of various encapsulating films on laser recrystallization of silicon on SiO 2: J B Lasky,J Appl Phys, 53 (12), 1982, 9038–9042

Effects of various encapsulating films on laser recrystallization of silicon on SiO 2: J B Lasky,J Appl Phys, 53 (12), 1982, 9038–9042

Two-Beam Laser Recrystallization of Silicon on an Insulating Substrate

ABSTRACTLaser recrystallization of silicon on an insulating substrate has been carried out by irradiating polysilicon with both an Ar+ laser operating on all lines in the visible and a CO2 laser operating at 10.6 microns. These experiments were carried out over a variety of laser power densities and substrate temperatures. The use of the two lasers allowed for independent spatial control of temperature in both the polysilicon and the SiO2 layers and helped to reduce the strain at the polysilicon - SiO2 interface. We report the successful recrystallization of polysilicon films without substrate heating for two different silicon-on-insulator structures.

A Model for Cw Laser Recrystallization Including Reflectivity Effects

ABSTRACTA simple, practical model is developed for cw laser recrystallization of silicon and SOI structures, taking into account spatial variations in optical reflectivity. The power absorption is assumed to be uniform within each of three regions: the central molten spot, the annular two-phase region, and an outer annulus to account for absorption in the solid phase. Analytic expressions are obtained for the radial and depth dependence of the temperature, for the melt depth, the melt radius, the melt threshold, the crystallization threshold and the substrate melt threshold. SOI structures are considered and comparison with some experimental results shows excellent agreement.

Effects of various encapsulating films on laser recrystallization of silicon on SiO2

Single-crystal silicon-on-oxide was produced by laser recrystallization of a 0.6-μm polysilicon film deposited on 1 μm of thermal SiO2. Oriented growth commenced where the polysilicon film was in contact with the silicon substrate, and proceeded laterally over the fully recessed SiO2. Typical dimensions of the single-crystal silicon-on-oxide film are 25 μm by 7 mm. The laser annealing was done with several different encapsulating films above the polysilicon, including 11.0, 16.4, and 32.9 nm of Si3N4, 25 nm of SiO2, 25 nm SiO2 +32.9 nm Si3N4, and uncapped samples. In addition, samples were laser annealed with and without an 1100 °C N2 preanneal of the structure. The 1100 °C anneal reduced the nucleation of misoriented grains in all samples, and extended the range of useable powers for the Si3N4 capped samples. The 32.9-nm Si3N4 cap produced the smoothest film and the most efficient coupling of the laser light into the silicon. The maximum distance of single-crystal growth was the same for all nitrogen-annealed samples, and showed a weak dependence on the melt width induced by the beam used for recrystallization. TEM micrographs of the recrystallized silicon show that the defects lie predominantly in the 110 direction. Their density increases away from the seed region, and they coalesce to form the grain boundaries at the transition to polysilicon growth.