Stress Relief (Dry Polishing)

Stress Relief (Dry Polishing)
http://www.disco.co.jp/eg/solution/library/strelief.html



In recent years, the demand for ultra-thin die for use in mobile phones, stacked packages, and a myriad of other applications has been increasing. But a decrease in die thickness has also resulted in decreased die strength and increased die warpage. Stress relief improves die strength for greater viability while reducing die warpage for greater usability in stacks and thin packages. The chart below outlines the four main types of stress relief, including dry polishing, a proprietary DISCO process.

Dry Polishing CMP (Chemical Mechanical Polishing) Wet Etching Dry Etching





Figure 1: Major stress relief processes



Application

Dry polishing effectively removes the damage layer that inevitably remains after fine grinding. The result is a mirror finish on the wafer backside, increased die strength, and reduced die warpage.



The following graph shows die strength (as measured with the ball press test) at increasing amounts of material removal. DISCO research has demonstrated that 2 micrometers of removal provides optimum stress relief results.





Figure 2: Variation in die strength with DP removal depth





Machines

DISCO's polishers handle a wide variety of applications and are in-line configurable with DISCO grinders for greater wafer handling safety. In addition, DGP8760 offers grinding and polishing in one complete unit.



DFP8140 DFP8160 DGP8760







Dry Polishing Wheel

DISCO's specially-developed wheel for stress relief has the following features:

• Contains a non-diamond grit.

• Provides a mirror finish without saw marks.

• Uses no chemicals, slurry or water for reduced environmental impact.

• Improves cost of ownership through reduced water costs, etc.

Dry Polishing wheel















Kiru, Kezuru, Migaku Topics









Blade Dicing



Laser Dicing



Grinding



Stress Relief



Stress Relief (Dry Polishing)



DBG & Dry Etcher Process Flow



DBG



Others



Applications Example









Dicing



Grinding



Polishing



DBG



Solutions Support









Applications Support



Dicing and Grinding Service