How can we thin a wafer down to “ultra-thin”?

How can we thin a wafer down to “ultra-thin”?
What exactly is an ultra-thin wafer?

Typical thickness ranges (8″/12″ wafers as examples)

• Standard wafer: 600–775 μm

• Thin wafer: 150–200 μm

• Ultra-thin wafer: below 100 μm

• Extremely thin wafer: 50 μm, 30 μm, or even 10–20 μm

Why are wafers becoming thinner?

• Reduce overall package thickness, shorten TSV length, and lower RC delay

• Reduce on-resistance and improve heat dissipation

• Meet end-product requirements for ultra-thin form factors

Key risks of ultra-thin wafers

1. Mechanical strength drops sharply

2. Severe warpage

3. Difficult handling and transportation

4. Front-side structures are highly vulnerable; wafers are prone to cracking/breakage

How can we thin a wafer to ultra-thin levels?

1. DBG (Dicing Before Grinding)
   Partially dice the wafer (without cutting all the way through) so each die is pre-defined while the wafer remains mechanically connected from the backside. Then grind the wafer from the backside to reduce thickness, gradually removing the remaining uncut silicon. Eventually, the last thin silicon layer is ground through, completing singulation.

2. Taiko process
   Thin only the central region of the wafer while keeping the edge area thick. The thicker rim provides mechanical support, helping reduce warpage and handling risk.

3. Temporary wafer bonding
   Temporary bonding attaches the wafer onto a temporary carrier, turning an extremely fragile, film-like wafer into a robust, processable unit. The carrier supports the wafer, protects front-side structures, and mitigates thermal stress—enabling thinning down to tens of microns while still allowing aggressive processes such as TSV formation, electroplating, and bonding. It is one of the most critical enabling technologies for modern 3D packaging.