IGZO-TFT-2026-014
a-IGZO thin-film transistor on glass (bottom-gate, top-contact)
Identification
| Sample ID | IGZO-TFT-2026-014 |
| Title | a-IGZO thin-film transistor on glass (bottom-gate, top-contact) |
| Status | Completed |
| Operator | Dr. E. Yılmaz |
| Laboratory / Facility | MikroFab Cleanroom — Line A |
| Batch / Lot | LOT-2026-IGZO-03 |
| Parent Wafer ID | GLASS-Eagle-XG-W07 |
| Location (die x/y) | die (3,5) |
| Revision | B |
Substrate / Material
| Substrate Material | Corning Eagle XG glass |
| Supplier | Corning |
| Size | 2.5 × 2.5 cm |
| Thickness (µm) | 700.0 |
| Active Layer Material | a-IGZO (In:Ga:Zn:O 1:1:1) |
Environmental Conditions
| Ambient Temperature (°C) | 21.5 |
| Relative Humidity (%) | 42.0 |
| Cleanroom Class | ISO 6 (Class 1000) |
Notes
| Tags | TFT, IGZO, oxide-semiconductor, bottom-gate |
| Notes | Low-temperature (≤350 °C) process — reference lot for the flexible-substrate transfer target. |
Process Steps
Substrate cleaning (solvent + UV-Ozone) (Cleaning)
| Method | Solvent (acetone/IPA) |
| Chemicals / Sequence (e.g. Acetone→IPA→DI) | Acetone (US 5 min) → IPA (US 5 min) → DI rinse → N₂ |
| Duration (min) | 15 |
| Temperature (°C) | 25 |
| Equipment | Branson 2800 ultrasonic bath |
| Drying (N₂ blow / hotplate) | N₂ blow + 110 °C hotplate 5 min; then UV-Ozone 10 min |
UV-Ozone increased surface energy and improved wetting (contact angle <10°).
Gate metal — Mo sputtering (Thin-Film Deposition)
| Technique | Sputter |
| Material / Target / Precursor | Molybdenum (Mo) target |
| Purity | 99.95% |
| Equipment | AJA Orion 5 DC magnetron |
| Chamber Pressure | 3 mTorr Ar |
| Substrate Temperature (°C) | 25 |
| Gas Flows (e.g. Ar:O₂ 30:10 sccm) | Ar 30 sccm |
| RF Power (W) | 150 |
| Duration (min) | 8 |
| Rate (nm/min or Å/s) | 12 nm/min |
| Target Thickness (nm) | 100 |
| Measured Thickness (nm) | 98 |
Gate patterning (Mask 1) (Lithography)
| Mask | GATE — field 1 |
| Mask Version | v3 |
| Photoresist (type/tone) | AZ 5214E (image-reversal, positive/negative) |
| Resist Thickness (µm) | 1.4 |
| Exposure Tool | EVG 620 aligner |
| Wavelength (nm) | 365 |
| Dose (mJ/cm²) | 95 |
| Focus / Defocus | contact mode, 25 µm proximity |
| Development (solution/time) | AZ 726 MIF, 45 s |
| Hard Bake (°C/min) | 120 °C / 2 min |
Gate metal wet etch (Etching)
| Etch Type | Wet |
| Chemistry / Etchant | Mo etchant (H₃PO₄:HNO₃:CH₃COOH:H₂O) |
| Equipment | wet bench — fume hood 2 |
| Duration (min) | 1.5 |
| Rate (nm/min) | 70 nm/min |
| Selectivity | Mo:glass very high |
| Temperature (°C) | 25 |
| Profile (isotropic/anisotropic) | isotropic (slight undercut) |
| Target Depth (nm) | 100 |
| Measured Depth (nm) | 98 |
| Final Clean | DI rinse + N₂ |
Gate dielectric — SiO₂ (PECVD) (Thin-Film Deposition)
| Technique | PECVD |
| Material / Target / Precursor | SiO₂ (SiH₄ + N₂O) |
| Equipment | Oxford PlasmaPro 100 |
| Chamber Pressure | 1000 mTorr |
| Substrate Temperature (°C) | 300 |
| Gas Flows (e.g. Ar:O₂ 30:10 sccm) | SiH₄ 10 sccm : N₂O 710 sccm |
| RF Power (W) | 20 |
| Duration (min) | 12 |
| Rate (nm/min or Å/s) | 16 nm/min |
| Target Thickness (nm) | 200 |
| Measured Thickness (nm) | 205 |
k≈3.9 extracted from C-V; interface trap density is low (to be confirmed later by LCR).
Active layer — a-IGZO sputtering (Thin-Film Deposition)
| Technique | Sputter |
| Material / Target / Precursor | IGZO ceramic target (In₂O₃:Ga₂O₃:ZnO 1:1:1) |
| Purity | 99.99% |
| Equipment | AJA Orion 5 RF magnetron |
| Chamber Pressure | 5 mTorr |
| Substrate Temperature (°C) | 25 |
| Gas Flows (e.g. Ar:O₂ 30:10 sccm) | Ar 28 sccm : O₂ 2 sccm (6.7% O₂) |
| RF Power (W) | 80 |
| Duration (min) | 6 |
| Rate (nm/min or Å/s) | 5 nm/min |
| Target Thickness (nm) | 30 |
| Measured Thickness (nm) | 32 |
| Final step | O₂ partial pressure tunes the carrier density |
Active island patterning (Mask 2, wet) (Etching)
| Etch Type | Wet |
| Chemistry / Etchant | Dilute HCl (1:100) |
| Duration (min) | 0.5 |
| Rate (nm/min) | ~60 nm/min |
| Profile (isotropic/anisotropic) | isotropic |
| Final Clean | DI + N₂ |
Source/Drain metal — Ti/Au (e-beam) (Thin-Film Deposition)
| Technique | E-beam evaporation |
| Material / Target / Precursor | Ti (10 nm) / Au (90 nm) |
| Purity | Au 99.99% |
| Equipment | Temescal e-beam evaporator |
| Chamber Pressure | 2×10⁻⁶ Torr |
| Rate (nm/min or Å/s) | Ti 0.5 Å/s, Au 2 Å/s |
| Target Thickness (nm) | 100 |
| Measured Thickness (nm) | 101 |
| Final step | lift-off (Mask 3, AZ nLOF 2020) |
Channel: W/L = 100/20 µm. Clean lift-off; no edge bead.
Post-anneal temperature profile (Temperature Profile)
| Time (min) | Temperature (°C) |
| 0 | 25 |
| 30 | 300 |
| 90 | 300 |
| 150 | 25 |
300 °C / 1 h air anneal: reduces oxygen vacancies and improves Vth stability.
Transfer characterization (Id–Vg) (Measurement Binding)
| Instrument | Keithley 2636B dual-channel SMU |
| Calibration Status | Valid (last cal. 2026-03-12) |
| Uncertainty (±) | ±0.5% I, ±0.02% V |
| Caption | Transfer at Vds=10 V; Vg −10→+20 V. µ_sat, Vth, SS, Ion/Ioff extracted. |
µ_sat ≈ 11.4 cm²/Vs · Vth ≈ +0.8 V · SS ≈ 0.18 V/dec · Ion/Ioff ≈ 2×10⁸.
Lot closure approval (Approval / Signature)
| Performed by | Dr. E. Yılmaz |
| Reviewed by | M. Demir (process eng.) |
| Approved by | Prof. A. Kara (lab supervisor) |
| Date | 2026-05-08 |
| Role / Title | Process engineer / Lab supervisor |
| Statement | Flow met specification; sample added to the characterization pool. |