Germanium on sapphire substrates for system on a chip

Germanium on sapphire (GeOS) is proposed for system on a chip applications. Sapphire substrates are demonstrated to exhibit lower rf losses and superior crosstalk suppression compared with oxidised silicon handle wafers. Inductors on sapphire also show higher quality factor and better frequency response than those manufactured on an SOI platform. GeOS substrates have been manufactured by wafer bonding. Bond strengths of greater than 2900 mJ m−2 have been obtained. Thin GeOS has been achieved by He/H2 ion cut processes. A self-aligned W gate process on Ge has been established with processing temperature limited to 400 °C. P channel MOSTs exhibit low threshold voltage and a carrier mobility of about 400 cm2 V−1 s−1.