Material for metal line in semiconductor device, metal line in semiconductor device, and method for forming metal line in semiconductor device

A metal line in a semiconductor device, comprising:

• an oxide layer and a lower metal layer buried in the oxide layer;
• a barrier layer on a portion of a surface of the oxide layer including the lower metal layer;
• an alloy having an alloy material on the barrier layer;
• a reflectance reducing layer on the alloy;
• and
• a passivation layer surrounding the barrier layer, the alloy, and the reflectance reducing layer,
• wherein the alloy material includes an alloy having aluminum as a main material, and copper and an element X, and
• the element X has 1) a coefficient of thermal expansion (CTE) of greater than about 0.55 ppm/K and less than about 5 ppm/K, 2) a melting point (MP) of greater than about 3000° C., and 3) electronegativity of greater than about 2.2.

A method of forming a metal line in a semiconductor device, comprising:

• forming an oxide layer and a lower metal layer buried in the oxide layer on a semiconductor substrate;
• forming a barrier layer on a surface of the oxide layer including the lower metal layer;
• forming an alloy on the barrier layer;
• forming a reflectance reducing layer on the alloy;
• performing a photo and etching process to perform metal line patterning on the alloy;
• passivating the metal line patterned alloy, the barrier layer, and the reflectance reducing layer with an insulator;
• and
• performing heat treatment,
• wherein the alloy includes aluminum as a main material, and copper and an element X, and
• the element X has 1) a coefficient of thermal expansion (CTE) of greater than about 0.55 ppm/K and less than about 5 ppm/K, 2) a melting point (MP) of greater than about 3000° C., and 3) electronegativity of greater than about 2.2.