temporary

**Temporary Bonding Process** is **joining wafers during processing using temporary adhesive, enabling backside access while protecting frontside** — enables thinning, via formation. **Adhesive** low-melting-point polymer (LMPT) thermally activated. Cost-effective, widely available. **Carrier** temporary substrate (glass, dummy silicon) provides mechanical support. **Bond Strength** ~0.1-1 MPa adequate for processing forces but weak for easy de-bonding. **De-Bonding** heating adhesive above Tg (~120-150°C) loses strength. Wafer separates. **Residue** adhesive remains post-debond. Chemical cleaning removes (compatible solvents). **Mechanical** wedge/peel alternative to heating. Higher risk of circuit damage. **Electrostatic** ESD bonding via Coulomb attraction. Low residue. **Fusion** Van der Waals bonding (cleaned flat surfaces). No adhesive. Strong; difficult de-bonding. **Smart Cut** hydrogen implantation enables layer transfer via cleavage plane. **Adhesive Selection** cost, de-bonding ease, thermal stability, solvent compatibility. **Wafer Cleanliness** particles between wafers cause voids. Pre-bond cleaning critical. **Bonding Fixtures** ensure parallel, aligned contact. Vacuum chucks typical. **Pressure Control** uniform pressure ~0.5-2 MPa over entire wafer. **Temporary Bonding enables advanced processing** otherwise impossible; backside access essential.