Study On Surface Damage Of TSV Wafer In Thinning

In the chip manufacturing process,the technology is close to the physical limit with the line width technology less than 32 nm,it is difficult to integrate the higher density circuit and more functions on a single chip.Based on TSV(Through Silicon Via)three-dimensional packaging technology is considered to be an effective way to continue Moore's law.In order to understand the formation mechanism of the surface damage of TSV wafers in thinning process,molecular dynamics was used to simulate the thinning process of substrate,substrate-insulating interface,insulating layer interface processing mechanism of the three part structure is studied.Firstly,the thinning model of substrate(monocrystalline silicon)was established and the material removal mechanism was analyzed.The plastic removal process of monocrystalline silicon was analyzed based on structure and stress,and the effects of different loading conditions on the subsurface damage were analyzed.The results show that the material is removed in plastic way on the lower loading conditions,and there is only amorphous silicon in the surface.With the increase of loading conditions(such as increasing the diamond grain radius,increasing thinning depth),there could be nano-twinned defects in subsurface.In general,the subsurface damage depth decreases with the increase of grinding speed.Secondly,the characteristics of the substrate-insulating interface in thinning were studied.It is found that the subsurface damage depth of interface is much larger than other regions,because the lattice deformation of the interface region is difficult to recover.The grinding force fluctuated remarkably on the interface.Finally,the thinning characteristics of silicon dioxide material were analyzed.Insulating layer is more difficult to remove compared with single crystal silicon,so the interface between substrate and insulating appears step.The grinding force fluctuated remarkably on the interface,because it needs larger force to remove silicon dioxide in the same grinding depth.