Image Number 2 for United States Patent #5234864.
A method for interconnecting layers in a semiconductor device is disclosed. The device includes a lower conductive layer formed by capping a second conductive layer on a first conductive layer, a contact window formed in an inter-insulating layer on the lower conductive layer, and an upper conductive layer connected to the lower conductive layer through the contact window. The contact window is formed by removing a portion of the inter-insulating layer where the contact will be formed using a first etching gas, and removing a portion of the second conductive layer where the contact will be formed using a second etching gas. The contact resistance becomes uniform by preventing the formation of a non-volatile mixture in the contact window, and the reliability of the device is improved by planarizing the surface of the lower conductive layer.