Sealed-Interface Local Oxidation Technology

A new regime of local oxidation, dubbed SILO for Sealed-Interface Local Oxidation, is explored. In SILO processing, a film of silicon nitride is in intimate contact with the silicon surface. The ubiquitous native oxide is effectively eliminated by using nitrogen ion implantation into silicon or plas...

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Bibliographic Details
Published in:IEEE journal of solid-state circuits 1982-04, Vol.17 (2), p.184-191
Main Authors: John Chi-Hung Hui, Tzu-Yin Chiu, Wong, S.-W.S., Oldham, W.G.
Format: Article
Language:English
Subjects:
Integrated circuit technology
Ion implantation
Isolation technology
Lead compounds
Nitrogen
Oxidation
Plasma immersion ion implantation
Plasma materials processing
Semiconductor films
Silicon
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Summary:A new regime of local oxidation, dubbed SILO for Sealed-Interface Local Oxidation, is explored. In SILO processing, a film of silicon nitride is in intimate contact with the silicon surface. The ubiquitous native oxide is effectively eliminated by using nitrogen ion implantation into silicon or plasma-enhanced nitridation to form a "sealing film" of approximately 100-/spl Aring/ in thickness. The oxidation rate of both types of films is characterized and found to be nearly equivalent. A 100-/spl Aring/ film can mask the growth of 7000 /spl Aring/of oxide in wet oxygen at 950/spl deg/C. With a sealed interface it is found that the usual "bird's beak" formation is completely suppressed in local oxidation. An approximate theoretical analysis shows that even a very thin interfacial oxide, acting as a lateral diffusion path for the oxidant species, can lead to a significant bird's beak. With a sealed interface using a 90-/spl Aring/ film, the thick-oxide to bare-silicon transition region is chisel shaped, with approximately 45/spl deg/ slopes. The transition region is even more abrupt if a conventional LPCVD nitride film is deposited on the sealing film before patterning. However, for total nitride thicknesses greater than about 300 /spl Aring/, defects are generated along the pattern edges aligned in [110] directions. Crystal damage generated during oxidation is found to be due to the intrinsic stress in the LPCVD nitride film. Argon-ion implantation into LPCVD nitride is found to be effective in reducing the defect density. A defect-free abrupt profile is produced by combining SILO with a nitride-oxide sandwich.
ISSN:0018-9200
1558-173X
DOI:10.1109/JSSC.1982.1051714