a beol manufacturing process for forming a via process between two metal lines on a semiconductor wafer comprises depositing a portion of a first metal adhesion layer within a patterned via hole , followed by a cooling step . the cooling step is then followed by formation of the remainder of the first metal adhesion layer and formation of a second metal adhesion layer within the patterned via hole . this process of forming the remaining portion of the first metal adhesion layer can be referred to as a wafer load , unload , load process . by using a lul process , thermal history is minimized , which reduces al extrusion at the via interfaces .