Wafer backgrinding is a semiconductor device fabrication step during which wafer thickness is reduced to allow for stacking and high density packaging of integrated circuits (IC).

ICs are being produced on semiconductor wafers

Wafer (electronics)

A wafer is a thin slice of semiconductor material, such as a silicon crystal, used in the fabrication of integrated circuits and other microdevices...

 that undergo a multitude of processing steps. The silicon

Silicon

Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...

 wafers predominantly being used today have diameters of 20 and 30 cm. They are roughly 750 μm

Micrometre

A micrometer , is by definition 1×10-6 of a meter .In plain English, it means one-millionth of a meter . Its unit symbol in the International System of Units is μm...

 thick to ensure a minimum of mechanical stability and to avoid warping during high-temperature processing steps.

Smartcards, USB memory sticks, smartphones, handheld music players, and other ultra compact electronic products would not be feasible in their present form without minimizing the size of their various components along all dimensions. The backside of the wafers are thus ground prior to wafer dicing

Wafer dicing

Wafer dicing is the process by which die are separated from a wafer of semiconductor following the processing of the wafer. The dicing process can be accomplished by scribing and breaking, by mechanical sawing or by laser cutting...

(where the individual microchips are being singulated). Wafers thinned down to 75 to 50 μm are common today.
The process is also known as 'Backlap'

or 'Wafer thinning'.