Method for manufacturing metal line

A method for manufacturing a metal line comprises providing a substrate. A metal layer and a photoresist layer are sequentially provided on the surface of the substrate. The photoresist layer is subjected to an exposure step to form an exposure portion and an unexposed portion in the photoresist layer. A developing step is carried out using a developer to remove the exposed portion or the unexposed portion and expose a portion of the metal layer. After the developing step, the developer remains on the exposed portion of the metal layer. A plasma treatment is performed to form a hydrophilic functional group on the developer-remaining portion and the exposed portion of the metal layer. The exposed portion of the metal layer is etched using an etchant to remove the exposed portion of the metal layer. The etchant is bonded to the hydrophilic functional group on the remainder of the developer during the etching step to remove the remaining portion of the developer. The residual part of the developer can be effectively removed by plasma treatment, which can improve the accuracy and quality of the metal line pattern transfer and improve the etching process yield. The plasma can roughen the surface of the metal layer and enhance the adhesion of the material layer to the metal layer.