For wafers where die are separated by the DBG (Dicing Before Grinding) process, stress relief by plasma etching is performed to enable a significant improvement in die strength.
Stress relief using plasma etching is effective for wafers where die are separated using DBG.
Fig. 1 shows a die strength comparison graph before and after plasma etching.
Fig. 1: Die Strength Comparison Graph
Plasma etching is a grinding process using gas as a medium. Because etching also occurs between the die separated by the DBG process, it is effective in removing cutting damage on the die sides. Etching also causes rounding of the die edge. The combination of these two effects results in a significantly higher die strength.
Photo 1 shows a sample where plasma etching was performed after separating die by the DBG process.
Photo 1: Edge Appearance after DBG + Plasma Etching