As the Si substrate gets thinner the die strength of the devices after singulation becomes more important.
It is generally known that a nanosecond UV laser grooving process does not provide a sufficient die strength (typical 250 – 300MPa). A general request from the industry is to achieve a die strength value above 700MPa.
A second quality criteria is the burr height on the edge of the device after separation. More advanced packing is moving to (micro) bump die interconnect rather than wire bond. A UV nanosecond laser grooving process is not able to generate burr below 2um. These are some of the key quality improvements which the industry is looking for apart from no chipping and delamination in the adjacent active structures to the groove and a smooth perfect U-shape profile.
All these requirements can be addressed when moving towards a shorter pulse duration regime. ASMPT has developed a laser grooving technology based on a Ultra Short Pulse (USP) femtosecond laser which uses its patented multi beam matrix grooving technology. In various applications such as Memory, logic and driver IC’s the process parameters have been optimized to achieve the above-mentioned quality criteria.