Method for forming patterned mask layer

A method for forming a patterned mask layer, comprising:

• forming a layer over a substrate;
• forming a first strip structure and a second strip structure over the layer;
• forming a spacer layer between the first strip structure and the second strip structure, wherein the spacer layer has a first strip part, a second strip part, and a connecting part, the first strip part and the second strip part are over a first sidewall of the first strip structure and a second sidewall of the second strip structure respectively, the connecting part is connected between the first strip part and the second strip part, the spacer layer has a first trench and a second trench spaced apart from the first trench, the connecting part separates the first trench from the second trench, the first trench and the second trench pass through the spacer layer, and a first top surface of the connecting part is lower than a second top surface of the first strip part;
• forming a third strip structure and a fourth strip structure in the first trench and the second trench respectively;
• and
• removing the spacer layer, wherein the first strip structure, the second strip structure, the third strip structure, and the fourth strip structure together form a patterned mask layer.

A method for forming a patterned mask layer, comprising:

• forming a layer over a substrate;
• forming a first strip structure and a second strip structure over the layer;
• forming a spacer layer and a block structure between the first strip structure and the second strip structure, wherein the spacer layer has a first strip part, a second strip part, and a connecting part, the first strip part and the second strip part are over a first sidewall of the first strip structure and a second sidewall of the second strip structure respectively, the connecting part is connected between the first strip part and the second strip part, and the block structure is over the connecting part;
• forming a third strip structure and a fourth strip structure between the first strip part and the second strip part, wherein the block structure is between the third strip structure and the fourth strip structure;
• removing the block structure;
• and
• removing the spacer layer, wherein the first strip structure, the second strip structure, the third strip structure, and the fourth strip structure together form a patterned mask layer.