Pb-based solders are used as high temperature solders in power semiconductor devices. Although use of Pb is globally restricted, alternative materials are inadequate to replace Pb-based solder. This study aims to replace Pb-based solder with an intermetallic compound (IMC). Samples were produced to join a Si chip with evaporated Ag and Sn films onto a Ag-plated Cu substrate at 523 K for 10 s. As a result, the evaporated films were completely transformed into a Ag3Sn IMC. The IMC joint showed higher strength until 543 K and good heat-aging resistance at 423 K. Therefore, this joint would be promising in replacing Pb-based solders.