TY - BOOK

T1 - Micro-Mechanical Characterization of Silicon based Dielectric Films and Metal/Dielectric Interfaces

AU - Matoy, Kurt

N1 - no embargo

PY - 2009

Y1 - 2009

N2 - In this thesis novel techniques are developed to study the mechanical behavior of monolithic silicon oxide, oxynitride and nitride thin film materials as well as multi-layers and interfaces between amorphous oxide layers and metallic films. All techniques developed are based on the micro-cantilever deflection technique and provide information about the Youngs modulus, the fracture stress and the fracture toughness. For the evaluation of the fracture toughness an analytical solution, which is based on finite element calculations, is provided. For the monolithic materials increasing Youngs moduli of up to 168 GPa, fracture stresses of up to 8 GPa and fracture toughness values of up to 1.6 are observed with increasing nitrogen content. It is shown that the observed fracture stress values correspond to critical defect dimensions of about 10 nm in size. The results obtained are compared with nanoindentation measurements. Additionally, a study on the influence of the specimen size on the fracture stress is performed. Therefore, multi-layer and monolithic cantilevers with layer thicknesses ranging between 50 nm and 2380 nm are tested. A slight increase in fracture stress with decreasing specimen size is observed, which can be assigned to the Weibull size effect. Moreover, interfaces between buried metal layers and inter-level dielectric layers are mechanically characterized with a novel method. By using focused ion beam machining bi-material cantilevers are produced with interfaces perpendicular to the axis of maximum tensile stress. An analytical solution, which is confirmed by finite element J-integral calculation, is provided for evaluating the obtained data. The model interface silicon oxide/copper was tested and agreement with literature data is demonstrated. It is shown that the interface toughness between sputtered tungsten barrier layers and silicon oxide dielectrics can be significantly increased if titanium is added to the tungsten film. In microelectronic industry this has already been qualitatively known, however, a quantitative miniaturized fracture test has not been reported until now.

AB - In this thesis novel techniques are developed to study the mechanical behavior of monolithic silicon oxide, oxynitride and nitride thin film materials as well as multi-layers and interfaces between amorphous oxide layers and metallic films. All techniques developed are based on the micro-cantilever deflection technique and provide information about the Youngs modulus, the fracture stress and the fracture toughness. For the evaluation of the fracture toughness an analytical solution, which is based on finite element calculations, is provided. For the monolithic materials increasing Youngs moduli of up to 168 GPa, fracture stresses of up to 8 GPa and fracture toughness values of up to 1.6 are observed with increasing nitrogen content. It is shown that the observed fracture stress values correspond to critical defect dimensions of about 10 nm in size. The results obtained are compared with nanoindentation measurements. Additionally, a study on the influence of the specimen size on the fracture stress is performed. Therefore, multi-layer and monolithic cantilevers with layer thicknesses ranging between 50 nm and 2380 nm are tested. A slight increase in fracture stress with decreasing specimen size is observed, which can be assigned to the Weibull size effect. Moreover, interfaces between buried metal layers and inter-level dielectric layers are mechanically characterized with a novel method. By using focused ion beam machining bi-material cantilevers are produced with interfaces perpendicular to the axis of maximum tensile stress. An analytical solution, which is confirmed by finite element J-integral calculation, is provided for evaluating the obtained data. The model interface silicon oxide/copper was tested and agreement with literature data is demonstrated. It is shown that the interface toughness between sputtered tungsten barrier layers and silicon oxide dielectrics can be significantly increased if titanium is added to the tungsten film. In microelectronic industry this has already been qualitatively known, however, a quantitative miniaturized fracture test has not been reported until now.

KW - Passivierung

KW - Halbleiter

KW - Bruchmechanik

KW - Dielectric Films

KW - Semiconductor

KW - Fracture

M3 - Doctoral Thesis

ER -