Copper substrate transfer technology for silicon RF circuits

We present exploratory experiments on the waferscale transfer of silicon RF circuits to copper substrates. This approach allows for a well defined microstrip transmission line interconnect and a perfect electrical and thermal grounding. Freestanding stress-free 6-inch transferred copper substrates are demonstrated and RF measurements on passive microstrip transmission lines are presented. Additionally, we present a new method enabling the dicing of these copper substrates. In conclusion copper substrate transfer technology is attractive for circuits operating at microwave frequencies as well as for demanding applications at lower frequencies such as RF power transistors for mobile communication.