DocumentCode :
2555769
Title :
Cobalt stripping process integration for cobalt salicide residue improvement
Author :
Ong, Michaelina ; Ung, Wisley ; Chin, Chai Chin ; Sewoon, Seok
Author_Institution :
X-FAB Sarawak Sdn. Bhd., Kuching
fYear :
2008
fDate :
25-27 Nov. 2008
Firstpage :
609
Lastpage :
613
Abstract :
In 0.11 um and larger technology node non-volatile memory process integration, undesired cobalt salicide residue formation is found to degrade ohmic contact resistant and cause severe yield loss. TiN/Ti/Co stack is applied in the process to get good CoSi2 formation. The abnormal salicide residue formation is detected after cobalt stripping process which is applying a two step selective wet etching. First, the wafer is etched in H2SO4/H2O2 (SPM), rinsed in de-ionized water and then etched in NH4OH/H2O2/H2O (APM). It was found that the higher concentration of H2O2 in the SPM when the SPM life time is getting older caused this abnormal salicide residue formation. This paper presents the detail studies of this residue formation mechanism and works that have been carried out to optimize the selective wet etching process including the SPM & APM process sequence and the etching time. By implementing the optimum selective wet etching condition, we are able to suppress the cobalt salicide residue formation.
Keywords :
cobalt compounds; etching; hydrogen compounds; integrated circuit yield; nitrogen compounds; ohmic contacts; random-access storage; surface contamination; titanium; titanium compounds; CoSi2; H2SO4-H2O2; NH4OH-H2O2-H2O; TiN-Ti-Co; cobalt stripping process integration; deionized water rinsing; nonvolatile memory process integration; ohmic contact resistant degredation; residue improvement; size 0.11 mum; wafer etching; wet etching process; yield loss; Chemicals; Cobalt; Degradation; Failure analysis; Nonvolatile memory; Ohmic contacts; Scanning probe microscopy; Tin; Water; Wet etching;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Semiconductor Electronics, 2008. ICSE 2008. IEEE International Conference on
Conference_Location :
Johor Bahru
Print_ISBN :
978-1-4244-3873-0
Electronic_ISBN :
978-1-4244-2561-7
Type :
conf
DOI :
10.1109/SMELEC.2008.4770399
Filename :
4770399
Link To Document :
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