FULTEC / RPI GaN MESFET Process Flow Revision B Last Updated 1/20/06 CONFIDENTIAL-Do Not Copy
FULTEC / RPI GaN MESFET Process Flow Substrate (Sapphire) Seed Layer Undoped Buffer Layer (AlN or AlGaN) N-doped GaN CONFIDENTIAL-Do Not Copy
FULTEC / RPI GaN MESFET Process Flow MASK M1 Digitized Dark Substrate (Sapphire) Seed Layer Undoped Buffer Layer (AlN or AlGaN) N-doped GaN Photoresist Mask M1: Mesa Aligned to: None Photoresist Masked Dry Etching (ICP or ECR) of GaN (~0.8mm) CONFIDENTIAL-Do Not Copy
FULTEC / RPI GaN MESFET Process Flow Mask M2: Gate Recess Etch MASK M2 Digitized Clear Substrate (Sapphire) Seed Layer Undoped Buffer Layer (AlN or AlGaN) N-doped GaN Photoresist Mask M2: Gate Recess Etch Aligned to: M1 Photoresist Masked Dry Etching (ICP or ECR) of GaN (~0.3mm) CONFIDENTIAL-Do Not Copy
FULTEC / RPI GaN MESFET Process Flow MASK M3A* Digitized Clear Substrate (Sapphire) Seed Layer Undoped Buffer Layer (AlN or AlGaN) N-doped GaN SiO2 Implantation Mask Mask M3A*: N+ Source/Drain Implantation (*Optional) Aligned to: M2 Photoresist Masked Dry + Wet Etching of Deposited / Densified Masking Oxide (1.5mm) N+ Implantation of Si (Dose=31015cm-2, xJ=0.2mm) 1100°C, 5 minute Activation Anneal CONFIDENTIAL-Do Not Copy
FULTEC / RPI GaN MESFET Process Flow MASK M3 Digitized Clear Substrate (Sapphire) Seed Layer Undoped Buffer Layer (AlN or AlGaN) N-doped GaN Field Oxide Photoresist Mask M3: Multi-Step Field Plate Etch Aligned to: M2 & M1 Photoresist Masked Dry Etching of Deposited / Densified Field Oxide (1mm deposited thickness etched to 0.25mm in window areas) CONFIDENTIAL-Do Not Copy
FULTEC / RPI GaN MESFET Process Flow Mask M4: Source & Drain Contact MASK M4 Digitized Clear Substrate (Sapphire) Seed Layer Undoped Buffer Layer (AlN or AlGaN) N-doped GaN Field Oxide Photoresist Mask M4: Source & Drain Contact Aligned to: M2 & M1 Photoresist Masked Dry + Wet Etching of Deposited / Densified Field Oxide (0.25mm to surface) Liftoff of Deposited Ti/Al Ohmic Contact Metal (50/200nm) Contact Annealing 600°C, 2 minutes, N2 CONFIDENTIAL-Do Not Copy
FULTEC / RPI GaN MESFET Process Flow Mask M5: Schottky Gate Metal MASK M5 Digitized Clear Substrate (Sapphire) Seed Layer Undoped Buffer Layer (AlN or AlGaN) N-doped GaN Field Oxide Photoresist Mask M5: Schottky Gate Metal Aligned to: M2 & M1 Photoresist Masked Dry + Wet Etching of Deposited / Densified Field Oxide (0.25mm to surface) Liftoff of Deposited Ni Schottky Gate Metal (200nm) CONFIDENTIAL-Do Not Copy
FULTEC / RPI GaN MESFET Process Flow Mask M6: Overlayer Metal MASK M6 Digitized Dark Substrate (Sapphire) Seed Layer Undoped Buffer Layer (AlN or AlGaN) N-doped GaN Field Oxide Photoresist Mask M6: Overlayer Metal Aligned to: M2 & M5 Deposition of Ti/Mo Overlayer Metal (200nm/400nm) Photoresist Masked Dry Etching of Deposited Metal CONFIDENTIAL-Do Not Copy
FULTEC / RPI GaN MESFET Process Flow MASK M7 Digitized Clear Substrate (Sapphire) Seed Layer Undoped Buffer Layer (AlN or AlGaN) N-doped GaN Field Oxide Passivation Layer DRAIN GATE SOURCE Mask M7: Pad Aligned to: M6 & M1 Photoresist Masked Dry Etching of Deposited Passivation Film (1mm) End of Process CONFIDENTIAL-Do Not Copy