Development of separation inspection technique for microcracks and particles using non-contact stress induced light scattering method

摘要

Fine-polishing techniques, such as chemical mechanical polishing treatments, are important techniques inglass substrate manufacturing. However, these techniques may cause microcracks under the surface of glasssubstrates because they use mechanical friction. We propose a Non-contact thermal Stress-Induced Light-Scattering Method (N-SILSM) using a heating device for inspecting surfaces to detect polishing-inducedmicrocracks. The N-SILSM can detect microcracks in a product under a ne-polished surface. It is atechnique for exposing microcracks by exploiting the change in light-scattering from microcrack tips due totemperature variation-induced stress. Additionally, optical properties change due to temperature variations.However, at manufacturing sites, it is ideal that inspection systems be able to distinguish between microcracksand tiny particles. In this report, we carry out the selective detection of microcracks and tiny particles usinga N-SILSM with temperature variation. Experimental results showed that the amount of change in the light-scattering intensity alters the cubic function regardless of the size of the microcracks, and also conrmed thattiny particles show very little change in light-scattering intensity. In addition, the possibility of microcracksize estimation was suggested from the magnitude of the change in light-scattering intensity. From theabove results, it has been shown that microcracks and tiny particles can be identied and measured by aN-SILSM utilizing temperature change, and that microcrack size estimation can be based on the change inlight-scattering intensity. Thus, it has been suggested that N-SILSM is a useful inspection technique fordistinguishing between microcracks and tiny particles.