Ion beam synthesis of epitaxial silicides: fabrication, characterization and applications

Ion beam synthesis of a buried SiO2 layer is an attractive silicon‐on‐insulator technology for high‐speed complementary metal‐oxide‐semiconductor circuits and radiation hardened devices. We demonstrate here a new annealing procedure at 1405 °C that produces silicon films of excellent quality, essentially free of oxygen precipitates and with sharp interfaces between the Si and the SiO2. Buried oxide layers have been formed in Si (100) wafers by implanting 400 keV molecular oxygen at 500 °C to a dose of 1.8×1018 cm−2. Annealing was performed by radiative heating of the back side of each sample to the melt temperature of silicon, TM=1412 °C, so that the buried oxide structure was at 1405 °C. The temperature control relies entirely on the change in optical properties of silicon upon melting. This ensures, without any external feedback, that the surface exposed to the photon flux will remain at TM.

High quality Si‐on‐SiO2 films by large dose oxygen implantation and lamp annealing

The incorporation of impurities into solids by bombardment with energetic ions is a non-equilibrium process which can result in intriguing near-surface property changes. This review initially examines the basic ion-solid interaction processes and outlines how such processes can lead to the modification of the composition, structure and surface topography of materials. Ion implantation has been exploited in widely diverse fields both as a powerful research tool for investigating solid state material processes and properties, and as a means of controllably modifying the electrical, physical, chemical, mechanical and optical properties of solid surfaces. These aspects receive major attention in this review which attempts to provide a balanced overview of the impact of ion implantation on solid state science and technology. In particular, special emphasis is given to implantation processes and applications in semiconductors which have received an enormous amount of attention in recent years, stimulated no doubt by the strong technological driving forces within the microelectronics industry. Ion bombardment processes and interesting property changes in metals are also discussed, and a selection of important technological applications is given. Finally, an overview of more recent investigations and applications is presented, including ion implantation into insulators and polymers, insight into crystal growth processes, adhesion of thin films to substrates, and research into ion bombardment of ices which has astrophysical significance.

https://iopscience.iop.org/article/10.1088/0034-4885/49/5/001/pdf

Materials modification with ion beams

Buried implanted oxide layers have been formed by high dose implantation of oxygen ions (3×1018 ions cm−2) into 〈100〉 silicon wafers, at a constant temperature of 500 °C. The implanted layers were studied by cross‐sectional transmission electron microscopy and secondary ion mass spectroscopy. The defects at both the top Si/SiO2 and the SiO2/bulk Si interfaces are shown to be SiO2 precipitates. The precipitates are unstable and can be eliminated by heat treatment, and a homogeneous top silicon layer with a low density of dislocations can be obtained.

Microstructure of silicon implanted with high dose oxygen ions

The properties of buried layers produced by the implantation of high doses of energetic light ions O+ and N+ are reviewed. Similarities and differences in the as implanted and annealed structures are discussed as are the effects of variations in the anneal temperature, time and ramp-rate. To assess the factors governing the interfacial displacements of the growing buried layer with respect to the silicon, experiments utilising buried marker layers and involving sequential implants of O+ or N+ ions were undertaken. These confirmed the results of 18O+ and 15N+ tracer experiments by showing that during implantation the back interface of the buried layer remains effectively fixed while the front interface is displaced towards the silicon surface. During the subsequent anneal redistribution of the implanted species occurs but again this effect is most marked at the front interface.

Fabrication of buried layers of SiO2 and Si3N4 a using ion beam synthesis

Formation of buried insulating layers in silicon by the implantation of high doses of oxygen

Oxygen distributions in synthesized SiO2 layers formed by high dose O+ implantation into silicon

SOI structures have been formed in (100) silicon by implanting 400 keV molecular oxygen to a dose of l.8×l0 18 O atoms cm −2 . These samples were annealed at 1150°C for 2 hours with a SILOX cap. Oxygen depth profiles have been determined by SIMS and wafers implanted at about 500°C have been characterized by studying the regrowth kinetics, As drive in and oxidation rate in the top silicon overlay.

J. Butcher

Papers

Formation of buried insulating layers in silicon by the implantation of high doses of oxygen

Oxygen distributions in synthesized SiO2 layers formed by high dose O+ implantation into silicon

Characterisation of Device Grade Soi Structures formed by Implantation of High Doses of Oxygen