Pt Sputtering

This page presents the results of Pt deposition using DC sputtering in Sputter-System (Lesker), now commonly known as "Old Lesker". The deposition target is Pt. Source #2 (DC) was used.

The fabrication and characterization described below were conducted in 2021 by Evgeniy Shkondin, DTU Nanolab. The focus of the study was the deposition conditions.

The process recipe in a Sputter-System (Lesker) is following:

Deposition type: DC
Power: 250 W.
Pressure: 3 mTorr
Gas: Ar
Deposition time: 60s
Temperature: 20°C (no heating)
Measured DC bias: 418V

Measured thickness (by XRR) is: 24.5 nm

Deposition Rate: 0.4078 nm/s

The characterization reveals a complex structure of the deposited layers. The best way to describe the samples is to implement the following model (shown in a figure). The Pt film contains a bottom intermediate layer with constant and relatively high electron density. On top of it, there is a main layer of Pt, where the density is a linear function of the depth. The highest density is at the top and the lowest at the bottom. The topmost layer contains moisture, where Pt bounds carbon and water. Appling this complexity allows fitting XRR data.

X-ray reflectivity (XRR) profiles for Pt film has been obtained using Rigaku XRD SmartLab equipment with standard 2\theta / \omega scans. The voltage and current settings for the Cu X-ray tube were standard 40kV and 30mA. The incident optics contained a IPS (incident parallel slit) adaptor with 5 ° Soller slit. Other slits: IS=0.03mm RS1=0.03mm and RS2=0.075mm. Step size: 0.01 and measurement time - 5s for each point. Fitting procesure was performed using commercial GlobalFit software assuming the model based on Si substrate with native oxide followed by the deposited complex Pt film illustrated on a model figure. The results are summarized in a tables below.

Layer parameter list
Layer name	Thickness (nm)	Density (g/cm³)	Rougness (nm)	Depth distribution	Bottom density (g/cm³)	Delta	Beta
Moisture	3.72	2.69	1.06	No distribution		8.7428e-6	2.0302e-7
Pt	23.39	18.75	0.38	Linear	2.03	6.0385e-5	6.2659e-7
Pt intermediate layer	1.078	6.60	0.39	No distribution		2.1479e-5	4.9878e-7
SiO₂ native oxide	2.16	1.75	0.52	No distribution		5.7113e-6	1.3262e-7
Si wafer	$\infty$	2.328	0.04	No distribution		7.5795e-6	1.7601e-7

XRR analysis of Pt thin film.
Pt sample model.
X-ray reflectivity. Measurement and Fit.