Study On The Vibration Of Wire Saw Slicing Process

Single crystal silicon is the foundation of semiconductor industry. Over 90% semiconductor device and circuit (especially the ultra large-scale integrated circuit) are made on the high quality polishing wafer and epitaxial wafer of single crystal silicon. With the increasing of the diameter of the wafer and the decreasing of the line width, the traditional inner saw can not fulfill the requirement of minor mechanical damage and complete crystal lattice. Because the wire saw technology has short history, it is lack of research about the mechanism of material removed and the optimization of parameter of process. This paper analyse the effect of the translating speed of wire, the feeding speed of workpiece, the initial tension of wire, the consistence of slurry, the granularity of SiC and diameter of silicon ingot of the wafer according to the acquisition of vibration of wire and the observation of surface roughness and quality of wafer. It is concluded that:1. According to the analysis of mathematic model of the vibration of wire, the divergence instability is generally not a concern because of the wire saw operating speed is very high but the density of wire is very small which result in a very high critical speed. The higher the translating speed of wire the bigger the vibration of wire and the power spectrum of vibration.2. The translating speed of wire is the important factor on the vibration of wire and the surface roughness, slicing accuracy of wafer. The smaller the translating speed of wire the bigger the vibration of wire and the surface roughness of wafer. The appropriate translating speed of wire is benefit to slow up the vibration of wire and reduce the surface roughness and TTV of wafer.3. The higher feeding speed of workpiece the bigger the vibration of wire, the surface roughness and TTV of wafer.4. The initial tension of wire is the important factor on the vibration of wire and the surface roughness, slicing accuracy of wafer. The bigger the tension of the wire the smaller the vibration of wire, the surface quality and TTV of wafer. 5. The bigger the consistence of slurry the more abrasive particle is got to the slicing area by the wire. The bigger the consistence of slurry the smaller vibration of wire, surface roughness and TTV of wafer.6. The smaller the granularity of SiC the more abrasive particle is got to the slicing area by the wire. |The smaller the granularity of |Si|C the smaller the surface roughness and TTV of wafer.7. The bigger the diameter of silicon ingot the more long the touch length of wire and the workpiece, and it make more abrasive particle is got to the slicing area. The bigger the diameter of silicon the bigger the apply force applied by the abrasive particle on the wire, the vibration of wire, the surface roughness and the TTV of wafer.