Laser-Assisted Processing of VIAs for AlGaN/GaN HEMTs on SiC Substrates

Published in:
IEEE Electron Device Letters, vol. 27, no. 6, pp. 425-427, June 2006.
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Abstract:
Vertical interconnect accesses (VIAs) were fabricated between the source electrode on the front and the ground on the backside of high-power microwave AlGaN/GaN high-electron mobility transistors (HEMTs) on ~ 400-µm-thick silicon carbide substrates. Through-wafer microholes with an aspect ratio of up to ~ 8 were drilled using pulsed UV-laser machining and subsequently metallized using electroplating. The successful implementation of the laser-assisted VIA technology into device processing was proven by dc and RF characterization.When biased at 26 V, a saturated output power of 41.6Wwith an associated power-added efficiency of 55% at 2 GHz was achieved for a 20-mm AlGaN/GaN HEMT with through-wafer VIAs.

Index Terms:
GaN, high-electron mobility transistor (HEMT), laser machining, laser materials-processing applications, semiconductor device fabrication, silicon carbide (SiC) substrate, vertical interconnect accesses (VIAs).

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