Photoacoustics (Aug 2024)

In-line imaging and recognition of flip chip fabrication defects by real-time photoacoustic remote sensing system

  • Jijing Chen,
  • Kaixuan Ding,
  • Yihan Pi,
  • Shoujun Zhang,
  • Jiao Li,
  • Zhen Tian

Journal volume & issue
Vol. 38
p. 100614

Abstract

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Microscopic defects in flip chips, originating from manufacturing, significantly affect performance and longevity. Post-fabrication sampling methods ensure product functionality but lack in-line defect monitoring to enhance chip yield and lifespan in real-time. This study introduces a photoacoustic remote sensing (PARS) system for in-line imaging and defect recognition during flip-chip fabrication. We first propose a real-time PARS imaging method based on continuous acquisition combined with parallel processing image reconstruction to achieve real-time imaging during the scanning of flip-chip samples, reducing reconstruction time from an average of approximately 1134 ms to 38 ms. Subsequently, we propose improved YOLOv7 with space-to-depth block (IYOLOv7-SPD), an enhanced deep learning defect recognition method, for accurate in-line recognition and localization of microscopic defects during the PARS real-time imaging process. The experimental results validate the viability of the proposed system for enhancing the lifespan and yield of flip-chip products in chip manufacturing facilities.

Keywords