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Process flow with Succinic Acid SpecMat Approval Request. July 10, 2009 Saeroonter Oh. Wafer substrate. Cap. 35nm. In 0.53 Ga 0.47 As. n + Si-doped 1e19 cm -3. 10nm. Al 0.48 In 0.52 As. Barrier. n-type Si-doping 5e12 cm -2. Al 0.48 In 0.52 As. 3nm. Channel. 13nm.
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Process flow with Succinic Acid SpecMat Approval Request July 10, 2009 Saeroonter Oh
Wafer substrate Cap 35nm In0.53Ga0.47As n+ Si-doped 1e19 cm-3 10nm Al0.48In0.52As Barrier n-type Si-doping 5e12 cm-2 Al0.48In0.52As 3nm Channel 13nm In0.53Ga0.47As Al0.48In0.52As Buffer 500nm InP Substrate (3in. or 4in.)
Process Flow • Mask#1: Gate pattern - karlsuss, headway • Wet etch w/ SA solution - wbgaas • Evaporate gate metal (Pt) - innotec • Anneal 250°C for 5 min - rtagaas • Lift-off in 1165 - wbsolvent • Mask#2: S/D pattern - karlsuss, headway • Wet etch w/ SA solution - wbgaas • Wet etch w/ HCl solution - wbgaas • Evaporate S/D metal (Au/Ge/Ni) - innotec • RTA (Standard: 450°C for 30sec) - rtagaas • Lift-off in 1165 - wbsolvent
Process Flow 1 2 3 PR PR Gate cap cap barr barr chan chan Mask #1, litho SA solution etch Gate metal evap lift-off RTA 4 5 6 PR PR Gate Gate Gate S/D Mask #2, litho SA solution etch + HCl solution etch S/D metal evap lift-off RTA
Etch Process: InGaAs on InAlAs • Succinic acid (SA) solution • 200g of crystal acid in 1L DI water • Addition of NH4OH for pH=5 • SA:H2O2 ratio changes etch rates • 5:1 used by D. Kim et al. • Etch rate: • 425 Å/min for InGaAs • 6 Å/min for InAlAs InGaAs 5:1 volume ratio InAlAs Ref: H. Fourre et al., J.Vac.Sci.Tech.B, 1996.