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Measurement Method for Optical Profilometry

Jochen Oberreiter

 

Through the ever progressing miniaturization trend of technical products as well as the steady increase in the production speed, it is essential for maintaining certain quality levels to develop more accurate and faster alternatives to the long prevailing visual assessment as well as adapting already established methods to the geometric characteristics of new components.

This study focuses on the measurement of (semi-)reflective surface structures of semiconductor components in the micrometer range under some very restrictive conditions on measurement methods and measurement speed. The presented method uses a standard pickup head of a CD or DVD-drive as a low-cost profilometry sensor. The advantage of using an ordinary CD pickup head for measurement purposes is that one gets a very precise optical system, buyable almost off the shelf at a reasonably low price. One disadvantage is that modifications to those systems are almost impossible due to the very compact package.

The results of various integrated circuit surfaces are presented and areas of application and limitations of the measuring method are discussed.

Keywords: measurement technology, pickup head, ball grid array, optoelectronics, profilometry, scanning, surface, topography, laser, sensor

October 1st, 2015

Figure 1: Measurement principle Figure 2: Measured surface detail of a ball grid array