Surface Treatment Method of PMMA Mold
Original Publication Date: 2002-Apr-11
Included in the Prior Art Database: 2003-Jun-20
Disclosed is a surface treatment method of PMMA (*1) mold for Ni (nickel) plating. On MEMS (*2) fabrication, PMMA is used as mold material for the 1st electro plating. After the 1st Ni plating with PMMA mold, resist material is applied on PMMA mold. The resist is used as mold for the 2nd electro plating. The resist exhibits formation of mixture with PMMA mold on the wafer substrate. The mixture calls intermixing layer, which has arround 1.8 micron in thickness on PMMA. And also the intermixing layer is spun on the surface of the 1st Ni layer. After the photolithography processing, the intermixing layer on the 1st Ni layer is remained. Because the 1st Ni is used as sead layer for the 2nd Ni electro plating, the remaining layer on the 1st Ni interferes with growth of the 2nd Ni plating. The problem results from poor reliabilty of wiring connection between the 1st and 2nd Ni. The approach here describes the use of plasma processing to treat a PMMA mold surface on wafer substrate for the purpose of preventing the formation of the intermixing layer. This technique is basically a two-step process: Sequence GAS FLOW POWER PRESSURE TIME 1. O2 plasma treatment··O2 80sccm 200Watt 100mtorr 150sec. 2. Ar plasma treatment Ar 80sccm 500Watt 35mtorr 100sec.