Suffered Silver peeling on ITO (indium tin Oxide), using HMDS for adhesion. Is contact angle check a good guage to check the adhesiveness? Silver is hydrophilic? and if my surface condition of ITO is hydrophilic too, will it stick due to no delta in Interfacial tension? OR the peeling is due to my HMDS remain or TMAH remain changing the surface condition after developing (open area, no resist? Or is it due to surface contanminant (example, organic compound or resist residue?) Scan show no residue at open area (on ITO surface).
Any solution on how to improve adhesion between ITO (oxide) and silver?
Btw, a O2 plamsa is impossible to use before Silver Evap, only annomia cleaning was used.
Hi Bobby,
HMDS is (typically) used to improve adhesion of a photoresist on silicon/silicon oxide wafers. It will not improve adhesion of metals - if anything it will make it worse (as you discovered). HMDS makes surfaces hydrophobic; polycrystalline silver is hydrophilic (see here: Article Hydrophilicity of metal surfaces. Silver, gold and copper electrodes
). In my opinion, silver films should stick very well to ITO; however, be sure you carefully remove any traces of TMAH and ammonia.Regards,
Leszek
Thank you Leszek, appreciate your opinion.
So i assumed that ITO & silver should be sticking well due to both are hydrophilic, same inter-facial tension.
It might be due to remain formed or contaminant after developing causing ITO surface not in optimum condition. Any idea, how to effectively remove TMAH? Will increase time/volume of DIW rinsing help? How do i check if there's any TMAH traces after developing ? Can i use contact angle as a guage?
I have an Ammonia clean before silver Evap, to help remove residue. i do not have O2 de-scum step before that. How will Ammonia traces affect the adhesion of silver?
Increasing the time of rinsing should help remove any traces of TMAH. I suspect that traces of ammonia severely affect the adhesion of silver. So again, careful rinsing with high purity deionised water should definitely help.
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