Abstract
In semiconductor manufacturing, fine-polishing process plays important role in achieving high-performance products. In recent years, driven by the escalating demand for process precision, the formation of latent flaws formation, which are defects that cannot be detected by general inspection, during fine-polishing process has emerged as a critical concern. Latent flaws cannot be observed with optical or electron microscopes and require destructive inspection such as etching for reliable detection. Previously, we have reported successful detection of latent flaws by applying stress [1] or heat [2,3] to the substrate.In this presentation, we present the development of a three-dimensional(3D) mapping approach for detecting latent flaws in glass substrates. Initially, defects were induced in a glass substrate through laser processing (532 nm). Subsequently, by observing the light scattering of the defects while adjusting the focus of the microscope, we analyzed not only the two-dimensional (2D) distribution of latent flaws but also their 3D distribution (Figure), with the addition of depth information. Understanding the depth of latent flaws is crucial, as it provides essential information for calculating the margin for shaving required for repolishing, which is necessary for removing the latent flaws and other defects. Furthermore, the 3D mapping information is anticipated to be valuable not only for optimizing polishing parameters but also for investigating any issues that may arise during the process.The data obtained from the described methods can be incorporated into a machine learning model to predict the depth of latent flaws from the image data. Our approach enables not only highly sensitive but also highly efficient inspection and is expected to make a significant contribution to the semiconductor manufacturing industry.[1] Yoshitaro Sakata et al. “Stress-induced light scattering method for the detection of latent flaws on fine polished glass substrates” REVIEW OF SCIENTIFIC INSTRUMENTS 85, 083303 (2014)[2] Yoshitaro Sakata et al. “Microscopic study of stress effects around micro-crack tips using a non-contact stress-induced light scattering method” AIP ADVANCES 6, 095315 (2016)[3] Yoshitaro Sakata et al. ” Development of a novel non-contact inspection technique to detect microcracks under the surface of a glass substrate by thermal stress-induced light scattering method” Optics & Laser Technology 90 80–83 (2017) Figure 1
Published Version
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