| abstract |
A compound semiconductor substrate such as a gallium arsenide substrate is eutectic and bonded to a metal substrate (400). The semiconductor substrate is thinned accordingly, and vias or trenches (601) are formed from the front side to the metal substrate (400) to facilitate aligned interconnections. The mechanical support provided by the metal substrate (400) allows the via or trench (601) to take any shape. The trench (601) can surround certain circuit elements to provide thermal isolation or thermal diffusion, or to allow electromagnetic shielding (in combination with a metal air bridge). The trench structure (601) also allows for a very short wave and low impedance ground connection compared to standard via holes. The metal substrate (600) can be used as a ground plane or as a heat sink. |