A thin film transistor array substrate with few processing steps and simple structure is provided, wherein merely two patterned metal layers are required and a patterned planarization layer is adopted to separate the two patterned metal layers from each other and thereby reduce power loading. A plurality of path endpoints are positioned along a perimeter of the matrix. Next, a first Ti film is formed on the interlayer insulating film. No item is delivered to any party involved in the barter until at least one other item, and possibly all other items involved in the transaction hashave been picked-up.