Micromachined thermosyphon for on-chip cooling of high-power InP HBT circuits

We present the development of a new on-chip heat transmission device called the "microthermosyphon". The microthermosyphon consists of a conical enclosure containing an electrically inert coolant fluid and is integrated on the surface of an InP HBT using 3D polymer micromachining. The microthermosyphon maintains the transistor temperature at the coolant boiling temperature (<100°C). The large surface-to-volume ratio of the working fluid at the micro-scale is expected to drive its internal coolant circulation without any external power supply and to achieve an efficient heat transmission from the transistor surface to a heat sink.