Manufacturing of nanometer structures in YBa2Cu3O7 thin films using a carbon based multilayer mask

Paper in proceeding, 1995

A process method that will produce ion milled bridges and trenches of ultra small dimensions in YBa2Cu3O7(YBCO) thin films is presented. The method is based on electron beam lithography, reactive ion etching (RIE), ion milling and a multilayer mask, which consists of an electron resist and an amorphous carbon layer with intermediate niobium. Carbon has two unique properties that are used in the process. First, carbon can easily be reactive ion etched in an oxygen atmosphere, since the oxides of carbon are gases. Furthermore, carbon has an extremely low ion milling etching rate. The electron resist pattern is transferred to the niobium and the carbon layers by a reactive ion etching process with CF4 and O2 In such a way a durable carbon mask for ion milling is formed. When the ion milling is completed, the result of the process is 50-60 nm wide bridges and 30-60 nm wide trenches in 100 nm thick YBCO films.