dry film

[seandepot123]

Dear all,
   I have difficulties encountered with photolithography process with dry film. I laminated dry film on 4 in. silicon wafer and the thickness of the dry film is 56um and my smallest dimension is 50um in diameter. I've followed data sheet process step by step and tried different exposure dosage (90 mj/cm2 to 109 mj/cm2, standard recommended 100 mj/cm2) and develop time and method (7 min to 13 min and spraying), but when I proceeded to electroplating process, it seemed like it has a thin layer of resist residues on the top of copper, which hindered copper electroplating. No matter how i increase or decrease the exposure dosage or develop time, it still have a thin/transparent layer on the top of copper in the hole. Before I proceeded to electroplating process, I have check under OM, which shows a clear hole or transparent layer (invisible film. After I electroplated it, it become visible, which some of successful developed hole gets plated (black color), while residues (yellow color) remained.

sorry i don't know how to post picture, but i have uploaded on a website for viewing pictures.

pic 0 (

) - after development, which is very clear

pic 1 (

) - this is the picture i took under OM after electroplating, the hole is 50um in diameter, it seemed like it has a thin layer of resist remain and the black dots in the hole which i assumed is the part which gets plated, and other yellow part is the residues.

pic 3 (

) - this is also after electroplating process, the ones get plated showed black color, the few ones in the in middle only plate on the edge with large yellow resist residues remain

pic 4 (

) - after electroplating process and 50 um in length as well, only half of the square gets plated.

Has anyone experience this kind of problems and might show me a way to solve it?

thanks a lot.