Stealth Dicing (SD) technology is an innovative laser dicing method, developed by Hamamatsu Photonics K. K., for semiconductor silicon wafers. In the advanced dicing process, a pulsed laser beam in the near-infrared region focused in a transparent wafer generates local modification regions, which become origins of cracks for separation. Owing to the non-contact and internal process, SD process has many advantages such as a completely dry process, high throughput, high quality, less kerf losses, and low running costs. The phenomenon of advanced dicing technology has not been sufficiently elucidated, and therefore many SD parameters have not been optimized although there are affect to dicing results. In this study, the laser modification phenomenon of SD in a Si wafer was investigated to focus on the actual phenomena. Firstly, the cleaved cross-section observation and nondestructive observation before cleaving has been conducted. Secondly, the subsurface time-resolved measurement have been proposed to observe SD mechanisms. Finally, in-situ observation of SD laser processing inside a Si wafer has been conducted to discuss the laser energy absorption phenomena. In addition, a few distinctive phenomena, including fine void structure with dislocation mapping, dynamics of transient absorption phenomenon inside the Si wafer after laser irradiation, and nanosecond-scale spreading of the laser shutoff phenomenon at SD laser focusing point, are confirmed.
Stealth Dicing(SD) method is superior to blade dicing as well as other laser dicing methods such as laser ablation in terms of debris free and fully dry process. Therefore, SD is used to solve various problems in the dicing process, contributing to development of advanced devices and cost reduction. In this paper, we introduced a improved SD engine(SDE) that solves the problem that thick wafers, which have been pointed out as weak points of SD, require many laser scanning. The laser with the wavelength in the short wavelength infrared(SWIR) region was used and the spherical aberration that occurred when internal focusing of silicon was corrected by using LCoS-SLM. As a result, the crack propagation from the SD layer was significantly enhanced, achieving 3.5 times the throughput of the conventional SDE in a silicon wafer with 300 μm thickness.