bonded soi

**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.