The dimensional measurement of micro objects using the linear scanning confocal surface shape measurement system

摘要

There are a lot of surface shape measurement methods. Appropriate method is selected from them in consideration of measurement accuracy, range, speed, etc. We have recently developed a system using a method among them called "linear scanning confocal surface shape measurement system"for measuring micro objects. In this paper, we describe the method to measure the horizontal dimensions of micro objects concurrently with the measurement of the vertical dimension using this system. Generally, it is difficult to get the focused image for the horizontal dimensional measurement of micro objects because of insufficient depth of field of the optics. However, as the system has plural images at multiple Z positions for vertical dimension measurement, we thought that the focus problem could be solved by calculating the focused image from these images. As a concrete example of micro objects, microelectrodes of semiconductor products are realistic. Microelectrodes are called bumps and electrically connects the integrated circuit chip and the package substrate. For guaranteeing the reliability of electrical connection, dimensional measurements of the bumps are required. Currently, as the density of integrated circuits increases, the arrangement density of bumps also increases. Therefore precise dimensional measurement of bumps is becoming important more and more. By using the bumps as the object under test and measuring its diameter, position and height, we confirmed the performance of developed dimensional measurement method on the system. The results showed that the system could measure a lot of bumps within a second with an accuracy of 1 urn or less.