Specific Process Knowledge/Thin film deposition/Gadolinium Cerium Oxide/Gadolinium Cerium Oxide in Cluster Lesker PC1
This page is written by Evgeniy Shkondin @DTU Nanolab if nothing else is stated.
All images and photos on this page belongs to DTU Nanolab.
The fabrication and characterization described below were conducted in 2023 by Patama Pholprasit and Evgeniy Shkondin, DTU Nanolab.
Sputtering of Gd0.2Ce0.8O2 in Cluster Lesker (PC1)
This page describes RF sputtering method of Gadolinium Cerium Oxide (Gd0.2Ce0.8O2) in Sputter-System Metal-Oxide(PC1) (Cluster Lesker).
Gadolinium-doped ceria (GDC) also known as gadolinia-doped ceria, gadolinium-doped cerium oxide (GCO) or cerium-gadolinium oxide (CGO), formula Gd0.2Ce0.8O2 is a ceramic electrolyte used in solid oxide fuel cells (SOFCs). It is an alternative to yttrium stabilized zirconium oxide. Material can be sputtered in our Cluster Lesker system. The results can vary depends on the applied method. Here we tested a 4 different cases: with and without additional oxygen, and with and without heating to 200°C. Since gadolinium-doped cerium oxide (GCO) is a ceramic material bonded to Cu backing plate a gentle ramp-up/down procedure needs to be implemented (max 0.3W/s). The applied power was 120W and pressure: 3 mTorr. Deposition time: 1800s
The 4 recipes are presented in 4 different cases:
- case1: No oxygen was added to the chamber at room temperature.
- case2: Small amount of oxygen added to the chamber at room temperature.
- case3: No oxygen was added to the chamber at 200 °C temperature.
- case4: Small amount of oxygen added to the chamber at 200 °C temperature.
More precise descriptions of recipes are presented in the following table below:
Recipe
| Parameters | Case 1 | Case 2 | Case 3 | Case 4 |
|---|---|---|---|---|
| mode | Upstream | Downstream | Upstream | Downstream |
| pressure (mTorr) | 3 | 3 | 3 | 3 |
| Power (W) | 120 | 120 | 120 | 120 |
| Ar flow (sccm) | - | 50 | - | 50 |
| O2 flow (sccm) | - | 2 | - | 2 |
| Temperature °C | 25 | 25 | 200 | 200 |
Uniformity across 150 mm wafer
Results have been obtained for <100> 150 mm Si wafers with native oxide, based on ellipsometry study.
| Case | Temperature (°C) | Added oxygen (sccm) | Average thickness (nm) | Minimum thickness (nm) | Maximum thickness (nm) | Standard deviation | Uniformity (%) | Deposition rate (nm/s) |
|---|---|---|---|---|---|---|---|---|
| case 1 | RT | - | 45.53 | 43.97 | 47.80 | 1.1418 | 4.2075 | 0.025 |
| case 2 | RT | 2 | 29.80 | 29.21 | 30.58 | 0.4722 | 2.3017 | 0.016 |
| case 3 | 200 | - | 30.59 | 29.69 | 31.67 | 0.6150 | 3.2266 | 0.017 |
| case 4 | 200 | 2 | 28.02 | 27.67 | 28.37 | 0.2436 | 1.2424 | 0.015 |
Thickness uniformity of GCO deposited on Si wafer using sputtering with no O2 reactive gas and at room temperature. 120W, 3 mTorr and 1800s. (Upstream).
Thickness uniformity of GCO deposited on Si wafer using reactive sputtering with 2 sccm O2 and 50 sccm Ar gas and at room temperature. 120W, 3 mTorr and 1800s. (Downstream)
Thickness uniformity of GCO deposited on Si wafer using sputtering with no O2 gas and at 200°C. 120W, 3 mTorr and 1800s. (Upstream)
Thickness uniformity of GCO deposited on Si wafer using reactive sputtering with 2 sccm O2 and 50 sccm Ar gas and at 200°C. 120W, 3 mTorr and 1800s. (Downstream)
Optical functions
Results have been obtained for <100> 150 mm Si wafers with native oxide, based on ellipsometry study. Sellmeier model has been implemented for refractive index fitting.
Refractive index of GCO deposited on silicon at room temperature (RT) and 200°C with and without 2 sccm O2 gas.
Absorption coefficient of GCO deposited on silicon at room temperature (RT) and 200°C with and without 2 sccm O2 gas.
