1. Field of the Invention
This invention relates generally to microelectronic devices, and more particularly to silicon carbide power devices and LEDs.
2. Description of the Background Art
Silicon carbide has relatively high thermal conductivity, and thus has been used as a substrate for high power devices and LEDs. However, because of the low mobility of silicon carbide and the incomplete ionization of impurities in silicon carbide, silicon carbide substrates used as back contacts in vertical devices have high resistance. For example, the substrate of a silicon carbide 300V Schottky diode contributes about two-thirds of the overall on-resistance of the device. A conventional approach to reduce parasitic loss due to substrate resistance involves the removal or thinning of substrate material. However, in the case of silicon carbide substrates, this approach can be considered disadvantageous, because it entails removal of silicon carbide which is an effective heat sink. Thus, a technology is sought to provide a substrate that is an effective heat sink, but that has a low resistance back contact that does not contribute significant loss during device operation.