Glass Wafer Edge Metrology and Inspection

Abstract

With the development of semiconductor technology and the growth of demand for smart devices in general life, manufacturing efficiency has become an increasing challenge for the industry. Wafer manufacturing, as the first step in the semiconductor manufacturing process, is the key to quality control. In wafer manufacturing, multiple processes take place on the wafer near-edge zone making defects more likely to occur. If the defective wafer is not detected during this process, material and energy will be wasted farther downstream. Near-edge zone inspection is restricted by cleanliness requirements, which makes optical inspection the most common methodology. The most direct optical method, near-field bright-field microscope, has drawbacks that the working distance is critical, and it gets shorter as the magnification is increased. Also, the depth of focus is tight, so limited information can be gathered in one capture, which results in the loss of important data. Dark-field inspection can get better topography information due to scattering reacting more sensitively on the surface roughness. This thesis proposes a novel dark-field microscope system with waveguide and white incident light. Glass wafers with defects of foreign particles, thin films, and grinding marks are tested. The benefits of this dark-field microscope system will be shown by comparing its contrast to a bright-field microscope. For identifying the defects, a color threshold method, Hue, Saturation, and Value method (HSV), and the sparkle analysis method will be used to determine the defect features. Overall, this work shows the potential of the waveguide dark-field microscope to be a low-cost and effective solution for wafer near-edge zone inspection.