Common IC large area delayering techniques, like broad ion milling, are prone to generate various types of irregularities. As a result, it is difficult to de-process an area of several mm² or even a full chip at a consistent, high quality especially when it comes to advanced nodes, like FinFET.
A simple tool for local mechanical adjustments has been successfully evaluated and has become an essential processing option to ensure excellent delayering performance. We re-purpose a vibrating pen-sized tool originally designed for dental lab applications. By using a fine tip of a material of choice in combination with diamond paste, the chip surface can be locally corrected and planarized.
We will discuss how to take advantage of the chip layers’ specific properties by employing this tool and present different use cases ranging from planarization of the chip surface during aluminium re-distribution layer removal to high quality delayering of 70nm thick BEOL metal layers in a 16nm node FinFET chip.