Interface characterization of Si{sub 3}N{sub 4}/Si/GaAs heterostructures after high temperature annealing
- Coordinated Science Laboratory and Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)
- NASA Lewis Research Center, Cleveland, Ohio 44135 (United States)
- Department of Physics and Astronomy and Center for Solid State Science, Arizona State University, Tempe, Arizona 85287-1504 (United States)
We present data on interface characteristics of Si{sub 3}N{sub 4}/Si/GaAs metal{endash}insulator{endash}semiconductor (MIS) structures and correlate electrical properties with spectroscopic ellipsometry, x-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) observations. The interface of Si{sub 3}N{sub 4}/Si/GaAs heterostructures was electrically characterized by a combination of capacitance{endash}voltage and conductance methods. The nature of an insulator/GaAs interface and the microstructure of Si{sub 3}N{sub 4}/Si/GaAs interfaces after high temperature annealing were investigated by variable angle spectroscopic ellipsometry and high resolution TEM, respectively. The evolution of chemical species in Si{sub 3}N{sub 4}/Si/GaAs heterostructures was examined using {ital in situ} angle-resolved XPS. The interface trap density (D{sub it}) of the Si{sub 3}N{sub 4}/Si MIS capacitor was in the 2{times}10{sup 10}thinspeV{sup {minus}1}thinspcm{sup {minus}2} range near the Si midgap after rapid thermal annealing at 550thinsp{degree}C in N{sub 2}. However, this density increased to high 10{sup 10}thinspeV{sup {minus}1}thinspcm{sup {minus}2} with annealing at 800thinsp{degree}C. The interface characteristics of Si{sub 3}N{sub 4}/Si/GaAs structures with D{sub it} in the 7{times}10{sup 10}thinspeV{sup {minus}1}thinspcm{sup {minus}2} range also degraded after annealing at 750thinsp{degree}C in N{sub 2} with D{sub it} increasing to 5{times}10{sup 11}thinspeV{sup {minus}1}thinspcm{sup {minus}2} near the GaAs midgap. The spectroscopic ellipsometry results together with high resolution TEM observations appear to suggest that the degradation is due in part to the interface changing from crystalline to amorphous through chemical reaction. XPS measurements revealed that the as-deposited Si interlayer is nitridated during the initial stages of silicon nitride deposition, thus the thinned Si cannot prevent the outdiffusion of Ga and As species. We circumvented thermally induced interface degradation of Si{sub 3}N{sub 4}/Si/GaAs structures by employing a novel {ital ex situ/in situ} growth approach. {copyright} {ital 1998 American Vacuum Society.}
- OSTI ID:
- 670203
- Journal Information:
- Journal of Vacuum Science and Technology. B, Microelectronics Processing and Phenomena, Journal Name: Journal of Vacuum Science and Technology. B, Microelectronics Processing and Phenomena Journal Issue: 6 Vol. 16; ISSN JVTBD9; ISSN 0734-211X
- Country of Publication:
- United States
- Language:
- English
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