Abstract: An improved contact hole plug and method are disclosed, the plug connecting a first conductive layer to a second conductive layer which is insulated from the first conductive layer. The contact hole plug may be formed using the steps of: (1) forming a first conductive layer consisting of a multi-layer metal (2) forming an inter-layer insulating film, and a contact hole therein; and (3) carrying out a rapid heat treatment which causes an alloy reaction in the multi-layer metal, and the resulting alloy expands to form a plug in the contact hole. The rapid heat treatment may be accomplished with a heat treatment furnace or a rapid thermal annealing (RTA) process at a temperature of 300.degree.-600.degree. C. for about 30 seconds (RTA) or 30 minutes (heating furnace).