Method of avoiding haze formation on surfaces of silicon-containing PECVD-deposited thin films
A method of PECVD deposition of silicon-containing films has been discovered and further developed. The method is particularly useful when the films are deposited on substrates having surface areas which are larger than 25,000 cm 2 . The method prevents the deposition of partially reacted silicon-containing species which form a powdery material or haze (contaminant compound) on the substrate surface. The contaminant compounds are avoided by assuring that the power applied to form a plasma in the PECVD process is maintained, at least at a minimal level, until reactive silicon-containing precursor gases present above the surface of the substrate have been reacted or evacuated from the plasma processing area.
1. A method of avoiding the formation of a powdery material on a surface of a silicon-containing PECVD-deposited film during completion of the silicon-containing film deposition, said method comprising:
a) discontinuance of a flow of all silicon-containing gas in a plasma source gas, optionally with accompanying adjustment of a flow of a portion of said plasma source gas which is non-silicon-containing and non-reactive with said silicon-containing film, so that a composition of deposited silicon-containing film is not affected;
b) maintaining a plasma in said non-silicon-containing, non-reactive plasma source gas for a minimum time period of about 0.5 seconds after discontinuance of said flow of all silicon-containing gas in said plasma source gas; and
c) subsequently shutting down power to said plasma, whereby said plasma is shut down.
2. A method in accordance with claim 1 , wherein subsequent to step b) and prior to step c) a step b-2) is carried out in which a film-forming gas is added to said step b) non-silicon containing plasma source gas for a time period sufficient to form a film over a surface of said silicon-containing PECVD-deposited film.
3. A method in accordance with claim 2 , wherein said film formed over a surface of said silicon-containing PECVD film is a transparent conductor film.
4. A method of avoiding the formation of a powdery material on the surface of a si 1 icon-containing PECVD-deposited film when an arc is detected in a plasma during deposition of said film, said method comprising:
a) detecting arcing in said plasma;
b) ramping down of power to said plasma, while maintaining a plasma;
c) adjusting of said power to said plasma until said plasma is stabilized;
d) continuing deposition of said PECVD-deposited film. including flow of said silicon-containing gas to said plasma;
e) discontinuing flow of a silicon-containing gas to said plasma; and
f) subsequent to step e) discontinuing power to said plasma after passage of a minimal time period ranging from about 0.5 second to about 3 seconds.
5. A method in accordance with claim 1 , wherein said time period during which a plasma is maintained after discontinuance of said flow of all silicon-containing gas ranges from about 0.5 seconds to about 3 seconds.