Effect of lubricant environment on saw damage in silicon wafers

The chemomechanical effect of lubricant environments on the inner diameter (ID) sawing induced surface damage in Si wafers was tested for four different lubricants: water, dielectric oil, and two commercial cutting solutions. The effects of applying different potential on Si crystals during the sawing were also tested. It is indicated that the number and depth of surface damage are sensitive to the chemical nature of the saw lubricant. It is determined that the lubricants that are good catalysts for breaking Si bonds can dampen the out of plane blade vibration more effectively and produce less surface damage. Correlations between the applied potential and the depth of damage in the dielectric oil and one of the commercial cutting solutions and possible mechanisms involved are discussed

Semiconducting/Semi-Insulating Reversibility in Bulk GaAs

Bulk, liquid‐encapsulated Czochralski GaAs may be reversibly changed from semiconducting (ρ∼1 Ω cm) to semi‐insulating (ρ∼107 Ω cm) by slow or fast cooling, respectively, following a 5 h, 950 °C soak in an evacuated quartz ampoule. This effect has been studied by temperature‐dependent Hall‐effect, photoluminescence, infrared absorption, mass spectroscopy, and deep level transient spectroscopy measurements. Except for boron, the samples are very pure, with carbon and silicon concentrations less than 3×1014 cm−3. Donor and acceptor concentrations, on the other hand, are in the mid 1015 cm−3 range, which means that the compensation is primarily determined by native defects, not impurities. A tentative model includes a donor at EC−0.13 eV, attributed toVAs−AsGa, and an acceptor at EV+0.07 eV, attributed to VGa−GaAs