Scanning Chemical Mechanical Polishing

Abstract

A new system design for chemical mechanical polishing (CMP) is used in semiconductor microchip manufacturing. In this new design, a wafer is placed on a vacuumed stage facing up, and the wafer surface is polished by a small size polishing pad assembled to a head which sweeps back and forth across the wafer. This new design differs from a conventional CMP system which holds a wafer facing down in a head while applying the pressure to the backside of the wafer, and pushes it onto on a big platen covered with a polishing pad. This new design eliminates the complicated multiple-zone head and its expensive components, while it provides a much robust way of profile turning which is critical to the performance of microchips. This new design also minimizes the usage of consumables and therefore greatly reduces the cost of manufacturing.

What is claimed is: 
     
         1 . A method of realizing chemical mechanical polishing process:
 A) A wafer  14  is sucked to a self-rotating stage  42  front-side up while a self-rotating smaller sized head  16  covered with pad  12  touching down on the wafer  14 .   B) The head  16  sweeps back and forth across the surface of the wafer  14  with applied down-force to remove the surface film and to reach planarization with the assistance of slurry  18 .   C) Sweeping route is divided into multiple zones  50 , and profile tuning is achieved through zonal sweeping methodology which allows the settings of different sweeping speeds and down-forces for each individual zone  50 .   
     
     
         2 . Wafer polishing using the method of  claim 1 , wafer cleaning and wafer drying are fulfilled in one unit. 
     
     
         3 . When the total removal amount is huge, it is feasible to combine the method of  claim 1  with a conventional CMP system. The conventional CMP completes the bulk polishing while the method of  claim 1  completes the final polishing to fine tune the final profile.