Advanced Materials Research Vols. 146-147

Abstract: This paper analyzes theoretically the contact length derived from elastic-plastic mechanics and microcontact theory with the aim of improving the traditional method of predicting roughness factor though experiments. The accuracy of the analysis is verified through experiments. It transpires from the theoretical model that the contact length between a grinding wheel and a workpiece increases with decreasing curvature radius of peak, increasing hardness of the workpiece as well as increasing depth of cut. It is also revealed that the contact length is directly proportional to the square of 0.32 of the hardness, approximately, whilst the square root of surface roughness and the density of peak of the grinding wheel show less influence on the contact length. The analysis method has reduced the variation between predicted and experimental values than that of the old methods. These results will be beneficial in analysing and designing the product quality of grinding.

Abstract: Temperature Coefficient of Resistance (TCR) is the important parameter in Electromigration Test of the metal reliability. The physical dimensions of the metallization can be affected by temperature. The coefficient of thermal expansion for a sample of the metallization can be used to approximate its change in volume given and a change in temperature. An object of uniform cross section will have a resistance proportional to its length and inversely proportional to its cross-sectional area, and proportional to the resistivity of the material. TCR is a fractional change in resistance per unit change in temperature at a specified temperature. In order to get the most reliable metal lines, lower TCR value is needed. Normally lower TCR value can be obtained if the grain size of the metal line is smaller. In this study, two types of metal process flows which are known as hot and cold metal is evaluated using TCR measurement. The hot and cold metal process use the same source of AlSiCu but the preparation for deposition is a bit different in which the hot metal process used temperature setting of 300oC, while the cold metal process the temperature is set at 175oC. From the result it is found that the metallization sheet resistance is linearly increase with increasing temperature and the TCR value also decrease with smaller line widths. From the FIB micrograph picture it is found that lower process temperature will give smaller grain size and lower TCR value.