DocumentCode :
2322414
Title :
Reliability failure induced by the Si epitaxy growth on PMOS high voltage oxide in 0.15μm embedded flash memory devices
Author :
Han, Sang Hyun ; Kim, Nam Sung ; Son, Dong Ju ; Mukhopadhyay, Madhusudan ; Wong, Wing Yew ; Zhang, Garlor ; Goh, Inn Swee
Author_Institution :
Syst. on Silicon Manuf. Co. Pte. Ltd., Singapore, Singapore
fYear :
2004
fDate :
15-17 Nov. 2004
Firstpage :
70
Lastpage :
74
Abstract :
It is discovered that Si Epitaxy causes charge to breakdown (Qbd) failure of mainly high voltage (HV) PMOS capacitors at shallow trench isolation (STI) intensive structure during the qualification of 0.15um embedded Flash memory process, and this Qbd failure rate is strongly related to the densification anneal process for STI gapfill oxide. It is confirmed that the higher thermal stress, the higher the Qbd failure rate. Even though the mechanism of Si epitaxy growth is not fully understood, the process induced stress at the corner of STI should be a major factor. The driving force of this stress induced Si epitaxy (SISE) is a localized thermodynamical instability. This SISE can be suppressed with lower thermal budget using rapid temperature anneal (RTA) for the densification of HDP oxides, instead of the furnace anneal in our 0.15um embedded Flash memory process. Furthermore, the missing Co silicide has been discovered precisely above the location of the SISE, and this missing silicide is strongly suspected to be correlated to SISE growth. We propose that the SISE induced high compressive stress causes the Co silicide to decompose into Co and Si to reduce the free energy of the poly gate/Co silicide region.
Keywords :
MOS capacitors; epitaxial growth; failure analysis; flash memories; rapid thermal annealing; 0.15 micron; Co silicide; PMOS capacitors; PMOS high voltage oxide; Qbd failure rate; Si epitaxy growth; densification anneal process; embedded flash memory devices; flash memory process; free energy; gapfill oxide; localized thermodynamical instability; process induced stress; rapid temperature anneal; reliability failure induced; shallow trench isolation; stress induced Si epitaxy; thermal stress; Breakdown voltage; Capacitors; Design for quality; Epitaxial growth; Flash memory; Qualifications; Rapid thermal annealing; Silicides; Thermal force; Thermal stresses;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Non-Volatile Memory Technology Symposium, 2004
Print_ISBN :
0-7803-8726-0
Type :
conf
DOI :
10.1109/NVMT.2004.1380807
Filename :
1380807
Link To Document :
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