Investigation of reactive ion etching of dielectrics and Si in CHF{sub 3}/O{sub 2} or CHF{sub 3}/Ar for photovoltaic applications
- Centre for Sustainable Energy Systems, Faculty of Engineering and Information Technology, Australian National University, Canberra, Australian Capital Territory 0200 (Australia)
Using a combination of etch rate, photoconductance, and deep level transient spectroscopy (DLTS) measurements, the authors have investigated the use of reactive ion etching (RIE) of dielectrics and Si in CHF{sub 3}/O{sub 2} and CHF{sub 3}/Ar plasmas for photovoltaic applications. The radio frequency power (rf-power) and gas flow rate dependencies have shown that the addition of either O{sub 2} or Ar to CHF{sub 3} can be used effectively to change the etch selectivity between SiO{sub 2} and Si{sub 3}N{sub 4}. The effective carrier lifetime of samples degraded upon exposure to a CHF{sub 3}-based plasma, reflecting the introduction of recombination centers in the near-surface region. The extent of minority carrier lifetime degradation was similar in both types of plasmas, suggesting that the same defects were responsible for the increased recombination. However, the rf-power dependence of lifetime degradation in n- and p-type Si was different. Moreover, the lifetime degradation did not exhibit a linear rf-power dependence, suggesting that primary defects were not the dominant recombination centers responsible for the decrease in lifetime. Indeed, DLTS measurements have shown that secondary defects were formed in samples exposed to the plasma after annealing at 400 deg. C, the temperature at which a SiN:H layer is deposited on samples to passivate their surfaces. The minority carrier lifetime degradation in RIE processed samples could be partially avoided using post-RIE chemical treatments.
- OSTI ID:
- 20853535
- Journal Information:
- Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films, Vol. 24, Issue 5; Other Information: DOI: 10.1116/1.2333571; (c) 2006 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1553-1813
- Country of Publication:
- United States
- Language:
- English
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