Journal of vacuum science & technology. B, Microelectronics and nanometer structures: processing, measurement, and phenomena: an official journal of the American Vacuum Society
A focused ion beam (FIB) has been used for Si submicron device fabrication. p‐n junctions and two... more A focused ion beam (FIB) has been used for Si submicron device fabrication. p‐n junctions and two terminal resistors were fabricated using a 60 keV Ga+ ion beam of diameter as small as 0.2 μm. Typical resistor dimensions were 50–160 μm in length and 0.2–0.5 μm in width. The Ga+ dose ranged from 5E13 to 5E14 Ga/cm2. I–V measurements showed the correct dependence of resistance on resistor length, width, and impurity concentration. We have studied the broadening of lines implanted in Si and SiO 2 using a fixed ion beam diameter as a function of dose level. Selective etch (H 3 PO 3 at 180 °C for Si and HF for SiO 2 ) and SEM analysis showed an increase of 50%–75% in linewidth as the dose was increased by an order of magnitude.
The biopolymer deoxyribonucleic acid (DNA) has been extracted from salmon (saDNA) and used succes... more The biopolymer deoxyribonucleic acid (DNA) has been extracted from salmon (saDNA) and used successfully as an electron blocking layer (EBL) in multiple structures of Organic Light Emitting Diodes (OLED). Water soluble saDNA was complexed with a cationic surfactant hexadecytrimethylammonium chloride (CTMA) which makes the resulting DNA-CTMA molecule water insoluble, and soluble in common organic media such as alcohols. Solutions of
ABSTRACTResults are presented on the fabrication of optical gratings on an Al0.3Ga0.7As/GaAs supe... more ABSTRACTResults are presented on the fabrication of optical gratings on an Al0.3Ga0.7As/GaAs superlattice (SL) with equal 3.5 nm barrier and well widths, by using locally FIB-enhanced mixing. As the first step, the mechanism of the mixing was studied. Si++ was accelerated to 50 kV and lOOkV and implanted at doses ranging from 1013 to 1015/cm2. A rapid thermal anneal of 10 s at 950°C was utilized. The average Al inter-diffusion coefficient and length were calculated as a function of FIB dose from SIMS depth profiling. The mixing was significantly enhanced by the FIB implantation. The ion dose as low as l×1014/cm2 followed by RTA yields a mixing parameter of ∼90% and results in a two-order of magnitude increase in the diffusion coefficient, to a value of 4.5×10−14cm2/sec, in contrast to 1.3×10−16cm2/sec from RTA-only. The maximum mixing occurred in the region where neither Si ions nor vacancies have their maximum concentration. Instead, it coincides with the location of the positive maximum of the second derivative of the vacancy concentration profile. This fact suggests that in the time frame of RTA and with low dose, the diffusion of nonequilibrium point defects plays a major role in the process of enhancing Al-Ga interdiffusion. DBR optical gratings, consisting of thousands of spacing lines with 350nm period, were fabricated with a lOOkV FIB dose of 2×1013 andl×1014/cm2. Photoluminescence (PL) spectra were taken from the grating region as well as the unimplanted superlattice region. The PL intensity from cavity region of the DBR was about 16 times higher than that from the original SL. This PL enhancement was verified to occur in the cavity region only by spatially scanning over the entire sample. A possible mechanism for this PL enhancement is optical feedback provided by the gratings.
ABSTRACTThe use of CHF3 plus oxygen plasma to achieve selective and anisotropic patterning of SiC... more ABSTRACTThe use of CHF3 plus oxygen plasma to achieve selective and anisotropic patterning of SiC thin films in the reactive ion etching (RIE) mode is reported. Experiments were performed using various levels of oxygen percentage (from zero to 90%), pressure (from 20 to 300 mTorr) and power (from 100W to 350W). Anisotropic etching of SiC with a vertical-to-lateral etch ratio in excess of 8:1 was measured for a CHF3 + 75%02 mixture at 20mT pressure and 200W RF power. Under these conditions, the SiC etch rate was measured to be 400 A/min and the selectivity over Si was approximately 2.2:1. The effect of the cathode DC potential and emission intensity of various species in the plasma on the SiC and Si etch rates is considered.
Journal of vacuum science & technology. B, Microelectronics and nanometer structures: processing, measurement, and phenomena: an official journal of the American Vacuum Society
A focused ion beam (FIB) has been used for Si submicron device fabrication. p‐n junctions and two... more A focused ion beam (FIB) has been used for Si submicron device fabrication. p‐n junctions and two terminal resistors were fabricated using a 60 keV Ga+ ion beam of diameter as small as 0.2 μm. Typical resistor dimensions were 50–160 μm in length and 0.2–0.5 μm in width. The Ga+ dose ranged from 5E13 to 5E14 Ga/cm2. I–V measurements showed the correct dependence of resistance on resistor length, width, and impurity concentration. We have studied the broadening of lines implanted in Si and SiO 2 using a fixed ion beam diameter as a function of dose level. Selective etch (H 3 PO 3 at 180 °C for Si and HF for SiO 2 ) and SEM analysis showed an increase of 50%–75% in linewidth as the dose was increased by an order of magnitude.
The biopolymer deoxyribonucleic acid (DNA) has been extracted from salmon (saDNA) and used succes... more The biopolymer deoxyribonucleic acid (DNA) has been extracted from salmon (saDNA) and used successfully as an electron blocking layer (EBL) in multiple structures of Organic Light Emitting Diodes (OLED). Water soluble saDNA was complexed with a cationic surfactant hexadecytrimethylammonium chloride (CTMA) which makes the resulting DNA-CTMA molecule water insoluble, and soluble in common organic media such as alcohols. Solutions of
ABSTRACTResults are presented on the fabrication of optical gratings on an Al0.3Ga0.7As/GaAs supe... more ABSTRACTResults are presented on the fabrication of optical gratings on an Al0.3Ga0.7As/GaAs superlattice (SL) with equal 3.5 nm barrier and well widths, by using locally FIB-enhanced mixing. As the first step, the mechanism of the mixing was studied. Si++ was accelerated to 50 kV and lOOkV and implanted at doses ranging from 1013 to 1015/cm2. A rapid thermal anneal of 10 s at 950°C was utilized. The average Al inter-diffusion coefficient and length were calculated as a function of FIB dose from SIMS depth profiling. The mixing was significantly enhanced by the FIB implantation. The ion dose as low as l×1014/cm2 followed by RTA yields a mixing parameter of ∼90% and results in a two-order of magnitude increase in the diffusion coefficient, to a value of 4.5×10−14cm2/sec, in contrast to 1.3×10−16cm2/sec from RTA-only. The maximum mixing occurred in the region where neither Si ions nor vacancies have their maximum concentration. Instead, it coincides with the location of the positive maximum of the second derivative of the vacancy concentration profile. This fact suggests that in the time frame of RTA and with low dose, the diffusion of nonequilibrium point defects plays a major role in the process of enhancing Al-Ga interdiffusion. DBR optical gratings, consisting of thousands of spacing lines with 350nm period, were fabricated with a lOOkV FIB dose of 2×1013 andl×1014/cm2. Photoluminescence (PL) spectra were taken from the grating region as well as the unimplanted superlattice region. The PL intensity from cavity region of the DBR was about 16 times higher than that from the original SL. This PL enhancement was verified to occur in the cavity region only by spatially scanning over the entire sample. A possible mechanism for this PL enhancement is optical feedback provided by the gratings.
ABSTRACTThe use of CHF3 plus oxygen plasma to achieve selective and anisotropic patterning of SiC... more ABSTRACTThe use of CHF3 plus oxygen plasma to achieve selective and anisotropic patterning of SiC thin films in the reactive ion etching (RIE) mode is reported. Experiments were performed using various levels of oxygen percentage (from zero to 90%), pressure (from 20 to 300 mTorr) and power (from 100W to 350W). Anisotropic etching of SiC with a vertical-to-lateral etch ratio in excess of 8:1 was measured for a CHF3 + 75%02 mixture at 20mT pressure and 200W RF power. Under these conditions, the SiC etch rate was measured to be 400 A/min and the selectivity over Si was approximately 2.2:1. The effect of the cathode DC potential and emission intensity of various species in the plasma on the SiC and Si etch rates is considered.
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Papers by Andrew Steckl