Physical mechanisms of hydrogen induced silicon surface layer cleavage were investigated using a combination of microscopy and spectroscopy techniques. The evolution of the silicon cleavage phenomenon is recorded by a series of microscopic images. The underlying hydrogen profiles under (between 250 and 500 °C) annealing are characterized by secondary-ion-mass spectroscopy and hydrogen forward scattering experiments. An idea gas law model calculation suggests that internal pressure of molecular hydrogen filled microcavities is in the range of Giga-Pascal, high enough to break silicon crystal bond. A dose threshold, which prevents cleavage, is observed at 1.6×1017 cm−2 for 40 kV hydrogen implantation.
Fluorinated amorphous carbon films have been deposited in a plasma-enhanced chemical vapor deposition system, and the optical properties examined by Fourier transform infrared and ultraviolet-visible absorption spectroscopy. The infrared absorption spectra in the region from 1000 to 1800 cm−1 were resolved into ten peaks, which were assigned to various carbon–fluorine and carbon–carbon vibration modes. A relationship between the optical band gap and the aromatic carbon (sp2) concentration is demonstrated.
Plasma enhanced deposition of amorphous aluminum nitride (AlN) using trimethylaluminum, hydrogen, and nitrogen was performed in a capacitively coupled plasma system. Temperature was varied from 350 to 550 °C, and pressure dependence of the film structure was investigated. Films were characterized by Fourier transform infrared, Rutherford backscattering (RBS), ellipsometry, and x-ray diffraction (XRD). The films are amorphous in nature, as indicated by XRD. Variations in the refractive index were observed in ellipsometric measurements, which is explained by the incorporation of carbon in the films, and confirmed by RBS. Capacitance–voltage, conductance–voltage (G–V), and current–voltage measurements were performed to reveal bulk and interface electrical properties. The electrical properties showed marked dependence on processing conditions of the AlN films. Clear peaks as observed in the G–V characteristics indicated that the losses are predominantly due to interface states. The interface state density ranged between 1010 and 1011 eV−1 cm−2. Annealing in hydrogen resulted in lowering of interface state density values.
Fluorinated amorphous-carbon (a-CFx) films deposited by plasma-enhanced chemical-vapor deposition were investigated by Fourier transform infrared transmission spectroscopy and Rutherford backscattering. The proportionality constant between the fluorine concentration and the integrated absorption of C–F vibration modes is 3.52±0.3×1019 cm−2, and is constant within experimental uncertainty over a wide range of processing conditions. It is shown that the fluorine content can be accurately determined from the infrared absorption spectrum of a-CFx films.
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