Innovative laser technology for semiconductor manufacturing – Stealth dicing

Abstract

When a permeable nanosecond pulse laser is focused into the interior of a silicon wafer and scanned in the horizontal direction, a belt-shaped high dislocation density layer with a partially polycrystalline region is formed at an arbitrary depth in the wafer. Applying tensile stress perpendicularly to this belt-shaped modified-layer separates the silicon wafer very easily into individual chips without creating any damage to the wafer surface compared with the conventional blade dicing method, because the internal cracks that spread from the modified layer up and down progress to the surfaces. This technology is called “stealth dicing” (SD), and attracts attention as an innovative dicing method in semiconductor industries. SD is an optimum solution for a dicing process of MEMS because it is a dry process. The formation mechanism of this modified layer has been investigated theoretically and it has been concluded that the high dislocation density layer and the internal cracks are generated due to propagation of a thermal shock wave caused by laser absorption. In this paper, the theoretical principle of the modified layer formation in SD and its superior features of SD are reviewed.When a permeable nanosecond pulse laser is focused into the interior of a silicon wafer and scanned in the horizontal direction, a belt-shaped high dislocation density layer with a partially polycrystalline region is formed at an arbitrary depth in the wafer. Applying tensile stress perpendicularly to this belt-shaped modified-layer separates the silicon wafer very easily into individual chips without creating any damage to the wafer surface compared with the conventional blade dicing method, because the internal cracks that spread from the modified layer up and down progress to the surfaces. This technology is called “stealth dicing” (SD), and attracts attention as an innovative dicing method in semiconductor industries. SD is an optimum solution for a dicing process of MEMS because it is a dry process. The formation mechanism of this modified layer has been investigated theoretically and it has been concluded that the high dislocation density layer and the internal cracks are generated due to propagatio...