Simulation of Dual-Target Magnetron Sputtering Process and Experimental Research
I. Experimental Research on Dual-Target Magnetron Sputtering
1. Experimental Background
Wide-bandgap semiconductor materials (such as GaN, ZnO, In₂O₃, Ga₂O₃, etc.) have been widely used in UV light-emitting devices, UV detectors, high-frequency devices, high-power devices, and radiation-resistant devices due to their excellent physical and chemical properties. However, these materials typically exhibit n-type conductivity when unintentionally doped, making it difficult to produce p-type materials, which limits their application scope. NiO thin films, with a bandgap width of 3.6 eV, usually exhibit p-type conductivity, compensating for the scarcity of p-type wide-bandgap semiconductor materials. By doping with suitable elements, the bandgap can be shifted towards shorter wavelengths.
2. Experimental Method
The experiment used a custom-made magnetron sputtering device from the Shenyang Scientific Instrument Factory of the Chinese Academy of Sciences. The vacuum chamber contained two RF target positions and one DC target position. RF targets with a diameter of 10 cm, thickness of 3 mm, and purity of 99.99% were installed for NiO and MgO ceramic targets. The sputtering gas used was high-purity Ar gas at a flow rate of 50 ml/min, with the sputtering vacuum maintained at 2 Pa and the substrate temperature at 300°C. The sputtering powers for the NiO and MgO targets were 190 W and 580 W, respectively. To ensure sample uniformity, the substrate rotated at a speed of 5 r/min, and the sputtering time was 45 minutes.
3. Results Analysis and Discussion
XRD Analysis: The prepared Mg-doped NiO thin films exhibited a (200) preferred orientation, with a flat surface, dense grain distribution, and grain size of approximately 46.9 nm. The XRD peaks shifted to smaller angles by about 0.2°.
Optical Properties: The films had high transmittance in the visible light region, but the transmittance dropped sharply around 300 nm, with an increased optical bandgap to 3.95 eV.
4. Conclusion
Using RF magnetron sputtering with two ceramic targets of NiO and MgO, high-quality Mg-doped NiO thin films were successfully prepared at 300°C in a pure Ar sputtering atmosphere with sputtering powers of 190 W for the NiO target and 580 W for the MgO target. The structure, morphology, composition, and optical properties of the films were studied using modern testing methods such as XRD, SEM, EDS, and UV-Vis spectrophotometry, revealing good crystalline structure and optical performance.
II. Simulation of Dual-Target Magnetron Sputtering Process
1. Simulation Background
Simulation of the magnetron sputtering process can help optimize experimental parameters and improve film quality. Simulations typically involve modeling plasma dynamics, target sputtering, particle transport, and film deposition.
2. Simulation Methods
Plasma Dynamics Simulation: By calculating the trajectories of electrons and ions in the plasma, the ionization rate of the sputtering gas and plasma density can be predicted.
Target Sputtering Simulation: Based on the physical properties of the target material and sputtering conditions, the sputtering rate and angular distribution of target atoms can be calculated.
Particle Transport Simulation: The transport process of sputtered particles in the vacuum chamber is simulated, considering collisions and scattering with gas molecules.
Film Deposition Simulation: The growth rate, thickness distribution, and microstructure of the film are predicted.
3. Comparison of Simulation Results with Experiments
Through simulation, parameters such as sputtering gas flow, vacuum level, and target power can be optimized to improve film uniformity and quality. Experimental results show that parameters optimized through simulation can significantly enhance film performance.
In summary, the simulation and experimental research on the dual-target magnetron sputtering process provide important technical support for the preparation of high-quality thin films. By optimizing experimental parameters and simulation models, the performance and application prospects of thin films can be further improved.
