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Optimization of LPCVD Thick Nitride Films Application to CMOS v LUNA E 16 Meg

IP.com Disclosure Number: IPCOM000112408D
Original Publication Date: 1994-May-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Raffin, P: AUTHOR

Abstract

Nitride haze is still an persistent problem in chip manufacturing (LPCVD processes) and so far only shortterm solutions have been found. Haze is known as surface bumps. Homogeneous nucleation provides germs and bumps are generated by a growth of germs. The incorporation and growth of germs into a film create a huge density of bumps on wafer surface. The most suggested mechanism occurs when the three following parameters are present : moisture, chlorides and saturation. As the concentration of the two first are given by process conditions, we focussed to work on gas saturation. Based on experiments, we found that we could avoid gas saturation by making the deposit in two steps. In between the two steps, byproducts are evacuated and the gas saturation involving cluster formation is never reached.

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Optimization of LPCVD Thick Nitride Films Application to CMOS v LUNA
E 16 Meg

      Nitride haze is still an persistent problem in chip
manufacturing (LPCVD processes) and so far only shortterm solutions
have been found.  Haze is known as surface bumps.  Homogeneous
nucleation provides germs and bumps are generated by a growth of
germs.  The incorporation and growth of germs into a film create a
huge density of bumps on wafer surface.  The most suggested mechanism
occurs when the three following parameters are present : moisture,
chlorides and saturation.  As the concentration of the two first are
given by process conditions, we focussed to work on gas saturation.
Based on experiments, we found that we could avoid gas saturation by
making the deposit in two steps.  In between the two steps,
byproducts are evacuated and the gas saturation involving cluster
formation is never reached.  By this way haze contamination is
eliminated and nitride deposition can be run back to back without
purging system in between runs.  The cycle time and tool throughput
are significantly improved.  The formation of residual particles and
tool set up time are strongly decreased.  This huge improvement of
foreign material level in thick nitride films pemitted us to
determine a upper particle density threshold limiting the deep trench
(DT) yield.  Moreover strong correlations were observed between final
wafer test and imbedded FM level.  Screen yield of EWR wafers (2-step
process) i...