The Dawn of the CD SEM came in the mid-eighties with Hitachi’s (now Hitachi High-Technologies) add-on accessory, the Model EP-1035. At the time, the semiconductor industry was realizing it sort chips at test for performance and return greater value for the higher performing ones. This became a significant factor in the shift from catching die yield problems at test to catching them in the fab at critical process steps. The best semiconductor companies quickly turned to trying to figure out how to better control the process in order to move the sort distributions to the right, so each wafer would yield more revenue. This “accessory” was the first step on the way to Hitachi’s revolutionary S6000.
You can’t control what you can’t measure. As it turned out, controlling Critical Dimensions (CDs) yielded the most fruitful results, but dimensions were too small to measure optically, hence the need for a SEM that could measure them. So this accessory was a key milestone in the advancement of the industry. As it turned out, controlling Critical Dimensions (CDs) yielded the most fruitful results, but dimensions were too small to measure optically, hence the need for a SEM that could measure them. So this accessory was a key milestone in the advancement of the industry.
