Bonded SOI is the dominant manufacturing method for SOI wafers — created by bonding two oxidized silicon wafers together and then thinning one of them down to the desired device layer thickness.

How Is Bonded SOI Made?

• Smart Cut™ Process (Soitec):

1. Oxidize Wafer A (forms BOX layer). 2. Hydrogen implant into Wafer A (creates a "weak plane" at target depth). 3. Bond Wafer A (face-down) to Wafer B (handle wafer). 4. Anneal: Hydrogen bubbles cleave Wafer A at the implant depth. 5. Polish: CMP the transferred thin Si layer to final thickness.

• Result: Ultra-uniform device layer (< 0.5 nm thickness variation).

Why It Matters

• Quality: Best crystalline quality — the device layer is bulk-quality single-crystal silicon.
• Scalability: Works for 200mm and 300mm wafers.
• Market Leader: Soitec's Smart Cut technology supplies >90% of the world's SOI wafers.

Bonded SOI is silicon transplant surgery — transferring a perfectly thin layer of crystal from one wafer to another using hydrogen-induced cleaving.