Source Wafer Research Articles

A 100 mA class ion implanter for large scale production of buried oxide SOI wafers

A new, fully automated, ion implanter suitable for large scale production of buried oxide wafers is presented. Novel solutions are employed to provide low cost, high quality, buried oxide with broad process range. Substrate temperatures are controlled between 400 and 750°C with a baseline 200 keV, 100 mA beam specification. By using a multiple beam filamentless source and robotic wafer handling, uniform low contamination specification wafers can be produced consistant with VLSI, class 1 to class 10 conditions. Typical throughput of 10 000 inch 2 per week (approximately 1000 wafers) can be obtained by careful beam utilization and the wafer cost less than 20% of those implanted on a 5 mA machine.

Near-equilibrium LPE growth of GaAs-Ga 1− xAl xAs double heterostructures

A system for the reproducible liquid phase epitaxial (LPE) growth of GaAs-Ga1−xAlxAs double heterostructures has been developed. The contamination of Al-bearing growth solutions with oxygen, and the consequent formation of Al2O3, has been eliminated by baking the Ga under H2 prior to the addition of Al. This procedure permits uniform wetting of the substrate by the melt and complete removal of the solution to terminate growth. By using a source wafer of GaAs to seed the solutions prior to arrival of the substrate, a condition of local thermal equilibrium is maintained at the growth interface at all times. Using these techniques we have reproducibly grown layers 0.15 μm thick. We have applied an isothermal diffusion model to simulate the growth of GaAs from a Ga-As solution. The results of this simulation verify the importance of maintaining local equilibrium near the growth interface. Using this simulation we have measured the diffusivity of As in Ga, D, and find D=8±1×10−5 cm2/sec at 800 °C.

Epr studies of the thermal decay of the OH radicals in electron irradiated lithium sulfate at 77°K

A system for the reproducible liquid phase epitaxial (LPE) growth of GaAs-Ga1−xAlxAs double heterostructures has been developed. The contamination of Al-bearing growth solutions with oxygen, and the consequent formation of Al2O3, has been eliminated by baking the Ga under H2 prior to the addition of Al. This procedure permits uniform wetting of the substrate by the melt and complete removal of the solution to terminate growth. By using a source wafer of GaAs to seed the solutions prior to arrival of the substrate, a condition of local thermal equilibrium is maintained at the growth interface at all times. Using these techniques we have reproducibly grown layers 0.15 μm thick. We have applied an isothermal diffusion model to simulate the growth of GaAs from a Ga-As solution. The results of this simulation verify the importance of maintaining local equilibrium near the growth interface. Using this simulation we have measured the diffusivity of As in Ga, D, and find D=8±1×10−5 cm2/sec at 800 °C.