• Title/Summary/Keyword: Wafer Pre-Aligner

Search Result 2, Processing Time 0.026 seconds

A Wafer Pre-Alignment System Using a High-Order Polynomial Transformation Based Camera Calibration (고차 다항식 변환 기반 카메라 캘리브레이션을 이용한 웨이퍼 Pre-Alignment 시스템)

  • Lee, Nam-Hee;Cho, Tai-Hoon
    • Journal of the Semiconductor & Display Technology
    • /
    • v.9 no.1
    • /
    • pp.11-16
    • /
    • 2010
  • Wafer Pre-Alignment is to find the center and the orientation of a wafer and to move the wafer to the desired position and orientation. In this paper, an area camera based pre-aligning method is presented that captures 8 wafer images regularly during 360 degrees rotation. From the images, wafer edge positions are extracted and used to estimate the wafer's center and orientation using least squares circle fitting. These data are utilized for the proper alignment of the wafer. For accurate alignments, camera calibration methods using high order polynomials are used for converting pixel coordinates into real-world coordinates. A complete pre-alignment system was constructed using mechanical and optical components and tested. Experimental results show that alignment of wafer center and orientation can be done with the standard deviation of 0.002 mm and 0.028 degree, respectively.

A Wafer Pre-Alignment System Using One Image of a Whole Wafer (하나의 웨이퍼 전체 영상을 이용한 웨이퍼 Pre-Alignment 시스템)

  • Koo, Ja-Myoung;Cho, Tai-Hoon
    • Journal of the Semiconductor & Display Technology
    • /
    • v.9 no.3
    • /
    • pp.47-51
    • /
    • 2010
  • This paper presents a wafer pre-alignment system which is improved using the image of the entire wafer area. In the previous method, image acquisition for wafer takes about 80% of total pre-alignment time. The proposed system uses only one image of entire wafer area via a high-resolution CMOS camera, and so image acquisition accounts for nearly 1% of total process time. The larger FOV(field of view) to use the image of the entire wafer area worsen camera lens distortion. A camera calibration using high order polynomials is used for accurate lens distortion correction. And template matching is used to find a correct notch's position. The performance of the proposed system was demonstrated by experiments of wafer center alignment and notch alignment.