Development of negative profile of dry film resist for metal lift off process

A dry film photoresist was selected as the sacrificial material for a metal lift off process. However, a weak and inconsistent adhesion of the evaporated under bump metallurgy (UBM) and solder on the passivation surface was observed during the dry film stripping process. This problem may be due to t...

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Bibliographic Details
Published in2009 11th Electronics Packaging Technology Conference pp. 884 - 888
Main Authors Chew, Michelle, Ho, Soon Wee, Su, Nandar, Liao, Ebin, Rao, Vempati Srinivas, Premachandran, C.S., Kumar, Rakesh, Damaruganath, Pinjala
Format Conference Proceeding
LanguageEnglish
Published IEEE 01.12.2009
Subjects
Adhesives
Costs
Inorganic materials
Materials science and technology
Microelectronics
Passivation
Resists
Standards development
Substrates
Testing
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Summary:A dry film photoresist was selected as the sacrificial material for a metal lift off process. However, a weak and inconsistent adhesion of the evaporated under bump metallurgy (UBM) and solder on the passivation surface was observed during the dry film stripping process. This problem may be due to the poor negative profile (88 to 89 degrees) of the patterned dry film side wall after dry film developing, resulting to inconsistent metal lift off. A few dry film predevelopment and post development parameters are identified and tested from the standard dry film development process, to obtain a negative profile of the dry film to be less than 84 degrees. After each test, cross section of the patterned dry film side wall is observed under a microscope to check if a negative profile is obtained. The 50 ¿m thick dry film at 35 mJ/cm 2 with other modifications of the process gives the best results.
ISBN:1424450993
9781424450992
DOI:10.1109/EPTC.2009.5416418