Electronic devices seem to get smaller and thinner with each new generation, which means extremely thin wafers are more in demand than ever. Wafers thinned using conventional wafer grinding methods often have a mirror-like surface. However, hidden to the naked eye is some degree of subsurface damage that is a result of the wafer grind process. Often this subsurface damage is only a few microns, depending upon the diamond grit size of the finish wheel used. To create a stronger more flexible wafer and die, this surface damage should be removed.
Chemical Mechanical Planarization (CMP)
One common method to remove this damage is Chemical Mechanical Planarization (CMP), also often referred to as wafer polishing. Post backgrind wafer polishing removes between 5 and 10 microns of silicon from the back side of the wafer. The end result is a dramatic reduction in the micro-sized peaks and valley micro-damage caused by the backgrinding process.
Syagrus Systems specializes in this subsurface damage removal polishing and post backgrind relief as part of the company's ultra-thin wafer solution. The company offers wafer polishing not just for freestanding thinned wafers, but can also polish wafers while still bonded to a carrier wafer such as the 3M Wafer Support System glass carrier wafer stack (see 3M Wafer Support System Process).
Wafer Polishing Process, Polishing Pads and Diamond Liquid SlurryDuring the polishing process, polishing pads and diamond liquid slurry are used to polish the wafer. The wafer is held in place by a vacuum carrier such that the backside of the wafer is exposed. The carrier and wafer are slowly brought into contact with a rotating platen, which is covered by a polishing pad. With a controlled downward force, we are able to carefully remove the damaged layers of the wafer, creating a stronger end product for the customer.
When working with thin silicon, keeping it damage-free is a challenge. That's why we recommend wafer polishing to remove the micro-damage that can result from the backgrind process. Wafer polishing is both highly effective and safe.
Have questions about Wafer Polishing? Contact Syagrus today to learn more about our Wafer Services
Contact Syagrus Systems today for more information on our wafer polishing services.