The present invention relates to a method of forming an interconnection for a semiconductor device using copper. The method of the invention, including the steps of forming an insulating layer having a groove on a semiconductor substrate containing active elements; forming and depositing a copper thin film on the insulating layer including the groove; and reflowing the copper thin film, may reflow the copper thin film deposited on the semiconductor substrate having a high-step surface for less than 30 min. below 450.degree. C., which show improved annealing conditions as compared with the conventional art. In addition, by reducing consumption of thermal energy in accordance with a low-temperature process, copper is restrained from being rapidly diffused through a silicon substrate, electrodes, etc. when forming the interconnection for the semiconductor device, thus improving productivity of the semiconductor devices.