Contact slots forming method applying photoresists include the following steps. A dielectric layer and a hard mask layer are formed on a substrate sequentially. A first patterned photoresist layer is formed over the hard mask layer, wherein the first patterned photoresist layer includes island patterns connecting to each other by connecting dummy parts. The hard mask layer is etched using the first patterned photoresist layer to form a patterned hard mask layer including island patterns connecting to each other by connecting dummy parts. A second patterned photoresist layer is formed over the patterned hard mask layer. The dielectric layer is etched using the second patterned photoresist layer and the patterned hard mask layer as a mask to form contact holes in the dielectric layer.