Patent ID: 8599352
Filing Date: 2013-12-03
Classification: G02F,H01L

Abstract:
1. A liquid crystal display device, comprising: a pair of substrates; liquid crystal sandwiched between the pair of substrates; a plurality of scanning signal lines formed on one of the pair of substrates; a plurality of image signal lines which intersect the plurality of scanning signal lines in a matrix form; a thin film transistor formed corresponding to each intersection between the plurality of scanning signal lines and the plurality of image signal lines; a pixel electrode which is formed in a pixel region and connected to the thin film transistor; a gate insulating film which substantially covers the plurality of scanning signal lines; and a protective insulating film which covers the plurality of image signal lines and the thin film transistor; wherein at least one of the plurality of scanning signal lines and the plurality of image signal lines are each formed of a laminated film including a first layer serving as a lower layer and a second layer which is formed on the first layer and serves as an upper layer; wherein the first layer is formed of a copper film having a purity of at least 99.5%, and the second layer is formed of an alloy film containing copper as a main component and having a higher etching rate compared with an etching rate of the first layer, the alloy film containing at least one element selected from the group consisting of cerium, europium, hafnium, lutetium, manganese, magnesium, lead, terbium, thulium, and zinc; and wherein the first layer and the second layer are collectively subjected to wet etching with an etchant having a pH smaller than 7.0, so as to form the laminated film including the upper layer of the second layer and the lower layer of the first layer into a forward tapered shape.