Laser, plasma etch, and backside grind process for wafer dicing

Abstract

Front side laser scribing and plasma etch are performed followed by back side grind to singulate integrated circuit chips (ICs). A mask is formed covering ICs formed on the wafer, as well as any bumps providing an interface to the ICs. The mask is patterned by laser scribing to provide a patterned mask with gaps. The patterning exposes regions of the semiconductor wafer, below thin film layers from which the ICs are formed. The semiconductor wafer is then etched through the gaps in the patterned mask to advance a front of an etched trench partially through the semiconductor wafer thickness. The front side mask is removed, a backside grind tape applied to the front side, and a back side grind performed to reach the etched trench, thereby singulating the ICs.

What is claimed is: 
     
         1 . A method of dicing a semiconductor wafer comprising a plurality of integrated circuits, the method comprising:
 forming a mask above the semiconductor wafer, the mask covering and protecting the integrated circuits;   patterning the mask with a laser scribing process to provide a patterned mask with gaps, exposing regions of the semiconductor wafer between the integrated circuits;   etching the semiconductor wafer through the gaps in the patterned mask to advance a trench partially through the semiconductor wafer; and   back side grinding the semiconductor wafer to reach the etched trench.   
     
     
         2 . The method of  claim 1 , further comprising removing the mask following the plasma etch and prior to the back side grinding. 
     
     
         3 . The method of  claim 1 , wherein the back side grinding further comprises applying a protection tape on a front side of the semiconductor wafer prior to the back side grinding. 
     
     
         4 . The method of  claim 3 , further comprising removing the protection tape from a backside of the semiconductor wafer after the plasma etch. 
     
     
         5 . The method of  claim 1 , wherein the semiconductor wafer has a diameter of at least 300 mm and has a thickness prior to the back side grinding of 300 μm to 800 μm. 
     
     
         6 . The method of  claim 1 , wherein patterning the mask further comprises direct writing a pattern with a femtosecond laser having a wavelength less than or equal to 540 nanometers and a laser pulse width less than or equal to 400 femtoseconds. 
     
     
         7 . The method of  claim 1 , wherein forming the mask further comprises depositing a water-soluble mask layer on the semiconductor wafer. 
     
     
         8 . The method of  claim 7 , wherein the water-soluble mask layer comprises PVA. 
     
     
         9 . The method of  claim 8 , wherein forming the mask further comprises depositing a multi-layered mask comprising the water-soluble mask layer as a base coat and a non-water-soluble mask layer as an overcoat on top of the base coat. 
     
     
         10 . The method of  claim 9 , wherein the non-water-soluble mask layer is a photo-resist or a polyimide (PI). 
     
     
         11 . A method of dicing a substrate comprising a plurality of integrated circuits (ICs), the method comprising:
 patterning, with a laser scribe process, a multi-layered mask disposed above a substrate to form a trench exposing regions of a substrate between the ICs;   plasma etching the substrate to advance the trench partially through substrate; and   back side grinding the substrate to reach the etched trench.   
     
     
         12 . The method of  claim 11 , further comprising removing the mask following the plasma etch and prior to the back side grinding. 
     
     
         13 . The method of  claim 11 , wherein the back side grinding further comprises applying a protection tape on a front side of the substrate prior to the back side grinding. 
     
     
         14 . The method of  claim 13 , further comprising removing the protection tape from a backside of the substrate after the plasma etch. 
     
     
         15 . The method of  claim 11 , wherein the substrate has a diameter of at least 300 mm and has a thickness prior to the back side grinding of 300 μm to 800 μm.