A Study of Flip Chip Microwave Device with Protecting Capability Submount

In this modern age, most of the semiconductor devices have a tendency of high integrated, high performance and high operating frequency. The chip feature size is decreased day after day. Therefore, to sink the excess heat in the correspondent device becomes an important issue for reliability. On the other hand, electric static discharge (ESD) problem shall also be considered which is now less considered in the microwave device area. We are now designing a high frequency and high power device in this project, the problem of heat dissipation and ESD handling capability must be considered in this proposal. Thus we proposed a flip-chip (FC) HEMT / MOSFET configuration, which we will flip the corresponding HEMT / MOSFET onto a protective submount. Many bumps will connect the chip and the submount, and form a dissipation path to sink the excess heat. GaN related HEMT / MOSFETs are known to be used in the high frequency high and power environment, this FC structure can further increase their thermal stability. Both ultrasonic and thermal bonding processes will be studied. During ball grid bumping, ball size, pad metal and submount temperature are all the issues of reliability. The surface treatment and many other parameters for the connection will also be detailed. A single FC device with high output power, impedance match, input transformer design, and high ESD handling capability will be fabricated in this proposal. At the end of this project, we will accomplish a single chip FC device with combined four paralleled GaN HEMT / MOSFETs that has no phase difference, no resonance, and full impedance matched. The goal of the output power for this single FC-HEMT / MOSFET device shall be above 15W.

Project ID:PB9709-3585
External Project ID:NSC97-2221-E182-052