Forming tapered pattern by Cu electrodeposition through mask on Ni seed layer for thin-film transistors

The fabrication of Cu gates for thin-film transistors (TFTs) by electrodeposition through mask on a Ni layer has been developed. After pretreatment in acid sulfate solution, a Cu deposit acquires the property of good adhesion on a Ni layer. Organic additives [e.g., poly(ethylene glycol) (PEG), bis(3-sodiumsulfopropyl) disulfide (SPS)] were used to create the desired tapered shape of the deposited Cu pattern on a Ni layer. Furthermore, a multilayer Cu gate for TFTs was fabricated after the selective etching of the nickel layer. The new method provides an alternative wet process for fabricating Cu gates for TFTs.