A gold-free fully copper metalized AlGaN/GaN power HEMTs on Si substrate

The thermal stability and reliability of AlGaN/GaN high electron mobility transistors (HEMTs) on Si substrates with a 2-μm thick copper interconnection (Cu-INTC) were evaluated. The use of metallic copper as a conducting metal has the advantages of higher thermal conductivity, low cost and low sheet resistance. For comparison, traditional gold metal interconnection (Au-INTC) devices were fabricated under the same process conditions. Thermal infrared (IR) microscopy measurements show that the Cu-INTC devices could function at a lower channel temperature (T _CHANNEL) than traditional Au-INTC devices with the same drain current density, because of the low resistivity of the metal. The typical peak transconductance (g _m), output power (P _OUT), power gain (Gp) and power-added-efficiency (PAE) during operation at 100 °C were 87.53 mS/mm, 22.85 dBm, 11.1 dB and 25.9% for a Cu-INTC power device with gate width of 1 mm and these measured results were better than those of Au-INTC devices. They indicate that the copper metal provides great potential for high-power AlGaN/GaN HEMT applications.