晶圓記號辨識的研究

STUDY ON WAFER IDENTIFICATION RECOGNITION

陳周楠(Chou-Nan Chen)

指導教授 ： 許超雲

大同大學/電機資訊學院/通訊工程研究所/碩士(2006年)

摘要

對半導體製造業的封裝、測試製程而言，將晶圓資料庫內的晶圓測試圖和測試結果與各晶圓記號連結是一件很重要的事。晶圓上的記號如同車牌一樣，具有唯一的識別號碼，含有許多的資訊，例如，此片晶圓的測試圖(wafer map)、晶圓內的晶片（die）是哪種型號等。
本論文所提出之晶圓記號辨識系統，包含前置處理、晶圓影像處理、晶圓記號字串的定位、晶圓字元切割、晶圓字元辨識等五大部分。
晶圓記號的辨識與車牌辨識相似，但有部分不同，例如，為了和其他晶圓製造商所生產的晶圓區別，則要求其晶圓記號為180度的反相。
為了簡化程式作業，前置處理：包含用定位片控制晶圓記號傾斜角度在+/-1度內、晶圓記號若是180度反相，則先旋轉為正常模式，再取RGB影像，接著以影像處理的技術，將讀入之影像處理成480X640解析度之灰階影像，再利用Otsu法找出門檻值，將灰階晶圓字串影像轉成二值化影像，再以Sobel邊緣偵測法找出晶圓字串的邊緣；在字元切割部分，利用垂直投影法找出晶圓字串的高度，再利用水平投影法找出晶圓字串的寛度，再將晶圓字元切割出來，最後，切割完成的晶圓字元以樣板比對法（Template matching），將晶圓字串影像中的晶圓字元辨識出來。
本系統從生產線擷取53張有晶圓記號的影像（各取自6英吋、8英吋、12英吋晶圓），來進行晶圓記號辨識的研究，實驗結果晶圓記號辨識成功率為81.1%，每張影像辨識時間約需2.2秒，雖然晶圓記號辨識成功率不是非常高但其優點是節省人力，對生產力的提升有很大的幫助。

關鍵字

晶圓記號

並列摘要

It is important for Assembly/Test process of semiconductor manufacturing to link wafer Identification (wafer ID) generated by Laser scribed with wafer Database. The wafer ID like a card plate license has a unique number and has much process information such as wafer test result which has been uploaded to wafer Database for successive processes such as dicing saw, die mount, wire bond, or final test.
This thesis proposed a recognizing wafer ID with the Template matching method to recognize the wafer ID engraved by Laser.
The wafer ID recognition system consists of pre-processing, image processing, locating wafer ID, segmenting characters from wafer ID, extracting character from wafer ID, and wafer ID output. In pre-processing, adjust a wafer with location pin to get less than 1 degree slope, focus on wafer ID window to simply process ,and rotate the wafer 180 degrees when the wafer is made by vendors; in the image processing, we convert a RGB image into a gray image which has been normalized to 480 by 640 resolution and then use Otsu’s method to find an adaptive threshold value which could automatically convert a gray image into binarized image, instead of trial and error to get a threshold value, finally use the Sobel edge detector to identify the edge of wafer ID; in locating wafer ID, first we use vertical projection method to decide the height of wafer ID string, and then use horizontal projection method to identify the width of wafer ID string; in segmenting characters, we use Template matching method to recognize the character of wafer ID image; and then display matching result from the recognize the character.
This system is evaluated by 53 wafer ID images from manufacturing. The successful rate of recognizing wafer ID is 81.1% which is not high rate but improving productivity. The average recognition time of each image is 2.2 seconds.

並列關鍵字

Wafer ID

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