RRAM-HfO2-2026-018

TiN/HfOₓ/Ti/Pt memristor — resistive-switching endurance

Identity

Sample ID	RRAM-HfO2-2026-018
Title	TiN/HfOₓ/Ti/Pt memristor — resistive-switching endurance
Status	Completed
Operator	B. Çelik
Laboratory / Facility	Nano-Device Research Group

Substrate / Material

Substrate Material	TiN / SiO₂ / Si
Active Layer Material	Sub-stoichiometric HfOₓ (≈10 nm, ALD)

Notes

Tags	RRAM, memristor, endurance, SET/RESET, oxygen vacancy
Notes	DOE condition O₂=8% (from PROJ-RRAM-2026-DOE). 50×50 µm device.

Process Steps

HfOₓ active layer — ALD (Thin Film Deposition)

Technique	ALD
Material / Target / Precursor	HfO₂ (TDMAHf + H₂O), oxygen-poor setting
Purity	99.99% precursor
Equipment	Beneq TFS200
Chamber Pressure	~1 mbar
Substrate Temperature (°C)	200
Duration (min)	25
Rate (nm/min or Å/s)	~1.0 Å/cycle, 100 cycles
Target Thickness (nm)	10
Measured Thickness (nm)	9.6
Final Step	Top electrode Ti(10 nm)/Pt(50 nm) e-beam, shadow mask

Electroforming + DC switching (Measurement Context)

Instrument	Keysight B1500A + WGFMU
Calibration Status	Valid
Uncertainty (±)	±0.5% I
Caption	Forming +3.2 V (compliance current 1 mA); then DC SET/RESET cycling.

V_SET ≈ +0.9 V · V_RESET ≈ −1.1 V · R_LRS ≈ 2.5 kΩ · R_HRS ≈ 180 kΩ (×72 window).

Endurance cycling (Measurement Context)

Instrument	Keysight B1500A — pulsed SET/RESET + read
Calibration Status	Valid
Uncertainty (±)	±0.5% R
Caption	Each cycle: SET pulse + RESET pulse + non-destructive read (0.2 V). R=\|V/I\|; LRS/HRS vs number of cycles.

MikroFab Endurance module (Figure S11 type). >10⁴ cycles; window started to close.

Endurance metrics (vs target) (Result (Spec))

Parameter	Value	Uncertainty (±)	Unit	Specification	Pass
First-failure cycle	1.4e4		cycles	≥1e4	✓
Initial HRS/LRS window	72	8	×	≥10	✓
Window at 10⁴ cycles	14		×	≥10	✓
V_SET	0.9	0.1	V	≤1.5	✓
Forming voltage	3.2	0.2	V	≤4	✓

Failure analysis comment (Free Note)

Window closure is most likely due to redistribution of oxygen vacancies in the filament (HRS decreasing). Increasing the top-electrode Ti thickness (oxygen getter) could improve endurance — a recommendation for the next DOE round.