| dc.description.abstract | In this work, a unique multi-step deposition technique in a pulsed DC sputtering system was employed to obtain trends of residual stress and film characters in aluminum nitride (AlN) thin films. The experiments were carried out by the 60-minute and the 30-minute process in one-step deposition. A multi-step (two and four-step process) deposition was carried out with equally separate processing time of the overall processing time being the same and turn off the power for 10 minutes during each interruption. The comparison of film characteristics between one-step deposition and multi-step deposition was used to study the correlation among film crystal orientation (state), residual stress and film features. The thickness, microstructure, residual stress, and crystalline state of AlN thin films were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and atomic force microscope (AFM). The results show that the AlN films have different stress characteristics in different microstructures when processed at the same amount of time in different deposition intervals. The increase in the degree of ion bombardment and induced substrate temperature raised leads to the interpretation for different microstructural changes in films. In this study, AlN films with thickness of about 1300 nm for the one-step deposition have a root mean square (RMS) surface roughness of 2.67 nm, a grain size of 65.1 nm, and residual stress of 1575 MPa. But by utilizing four-step deposition, these values were reduced to 2.46 nm RMS surface roughness, 51.4 nm grain size, and 841 MPa residual stress. More corresponding values and trends about the effect of multi-step deposition are described more details in the research. In-situ optical emission spectroscopy (OES) data were collected during plasma deposition of selected dominant wavelengths such as N2 (315 & 336 nm), and Al (394 & 396 nm) for large-scale data analysis. Residual stress data were analyzed to see if there is a link among OES data, crystalline state, and thin-film quality. Based on the cross-validation test executed from OES data preprocessing, the methodology with the principal component analysis (PCA) and value of microstructure characteristics (VMC) algorithm demonstrated that this multi-step deposition technique can provide a good stress gradient control from microstructural analysis and can be effectively classified for film characteristics of AlN deposition. | en_US |