Wafer Bonding | GINECHIP™

6 TechnologiesBonding Methods

<< 10⁻⁸ atm·cc/sHermetic Seal

RT–1100°CTemperature Range

< 2μmAlignment Accuracy

Overview

Wafer bonding is a critical process for permanently joining two wafers to form hermetic seals, create 3D stacked structures, or integrate dissimilar materials. GINECHIP offers six distinct bonding technologies spanning the full range from room-temperature direct bonding to high-temperature metal diffusion bonding for vacuum-tight MEMS encapsulation.

Whether your application requires anodic bonding of silicon to glass for pressure sensors, fusion bonding for SOI substrate fabrication, eutectic bonding for hermetic MEMS packaging, adhesive bonding for low-temperature heterogeneous integration, or metal diffusion bonding for ultra-high-vacuum cavities — our ISO Class 5 cleanroom bonding platforms deliver reliable, reproducible results with full bond quality metrology.

Bonding Technologies

Anodic Bonding (Si-Glass)

High-voltage (400–1200V) field-assisted bonding of silicon to borosilicate glass (Pyrex, Borofloat 33). Hermetic, permanent bond without intermediate layer. 300–450°C process. Ideal for pressure sensors, accelerometers, microfluidic devices.

Materials: Si to borosilicate (Pyrex®)Temperature: 300–500°CVoltage: 400–1000V DCVacuum: < 10⁻⁴ mbarBond strength: 10–20 MPaWafer: 100mm–200mm

Fusion Bonding (Si-Si, SOI)

Direct silicon-to-silicon bonding via high-temperature annealing (800–1100°C) after surface activation (plasma or RCA-1 clean). Atomic-scale bond strength. Wafer pairs for SOI fabrication, 3D memory stacking, and CMOS image sensor backside illumination.

Materials: Si–Si, Si–SiO₂, SiO₂–SiO₂Pre-bond: RT, ambient or vacuumAnneal: 800–1100°CSurface: Ra < 0.5nm requiredBond strength: bulk Si fractureWafer: 100mm–200mm

Eutectic Bonding (Au-Si, Au-Sn, Cu-Sn)

Metal-alloy bonding forming liquid eutectic at precise temperature (Au-Si 363°C, Au-Sn 280°C, Cu-Sn 227–415°C). Hermetic seal with electrical interconnection. MEMS wafer-level packaging, hermetic cavity sealing, RF device capping.

Systems: Au–Si (363°C), Au–Sn (280°C)Al–Ge (420°C)Application: pressure + temperatureHermetic seal: < 10⁻⁸ atm·cc/s HeBond frame: lithographically definedWafer: 100mm–200mm

Adhesive Bonding (Polymer)

Low-temperature (< 200°C) polymer bonding using BCB, SU-8, polyimide, or UV-curable epoxies. Compatible with temperature-sensitive materials. Roughness-tolerant (up to 2μm). 3D heterogeneous integration, CMOS-MEMS integration, temporary carrier bonding.

Systems: Cu–Cu, Au–Au, Al–AlTemperature: 200–400°CPressure: 20–100 MPaAtmosphere: N₂ or forming gas (Au)Bond interface: < 50nm void-freeWafer: 100mm–300mm

Metal Diffusion Bonding (Cu-Cu, Al-Al)

Solid-state atomic diffusion at elevated temperature (300–400°C) under controlled pressure and reducing atmosphere. Ultra-clean, sub-nm roughness surfaces required. Ultra-high-vacuum MEMS cavities, 3D-IC wafer stacking with through-silicon via interconnection.

Adhesives: BCB, SU-8, PI, epoxyTemperature: RT–250°CPressure: 0.1–1 MPaTolerates roughness, topographyBond line: 1–50μmWafer: 100mm–300mm

Glass Frit Bonding

Screen-printed low-melting-point glass paste bonding at 400–450°C. Thick bond line (5–20μm). High roughness tolerance. Cost-effective hermetic packaging for MEMS inertial sensors and pressure sensors with electrical feedthrough compatibility.

Adhesives: thermoplastic, UV-curableCarrier: Si or glass waferTemperature: 150–250°C (thermal)Laser: 308nm or 355nm releaseThickness tolerance: ±2μm TTVWafer: 100mm–300mm

Typical Applications

MEMS Encapsulation & Vacuum Packaging

Hermetic wafer-level encapsulation of inertial sensors (gyroscopes, accelerometers), RF MEMS switches, and micromirrors. Anodic and eutectic bonding with controlled cavity pressure from mTorr to atmosphere.

SOI & Engineered Substrate Fabrication

Fusion bonding + grind-back and Smart Cut process for SOI substrate fabrication. Device layer thickness 50nm–100μm. BOX layer 0.1–2μm. 200mm and 300mm wafers.

3D IC & Heterogeneous Integration

Metal diffusion (Cu-Cu) and adhesive bonding for wafer-to-wafer or die-to-wafer 3D stacking. Through-silicon via (TSV) compatible. Memory-on-logic, CIS stacking, interposer bonding.

Pressure Sensors & Microfluidics

Anodic Si-glass bonding for absolute and differential pressure sensors. Fusion bonding for resonant pressure sensors. Glass frit bonding for media-compatible sensors. Cavity pressure control from vacuum to reference pressure fill.

Optical MEMS & Photonics

Low-temperature adhesive bonding for photonic integrated circuit integration. Eutectic bonding for laser diode and VCSEL packaging. Hermetic sealing with optical window for DMD and micromirror arrays.

RF & mmWave Device Packaging

Eutectic Au-Sn bonding for low-loss RF interconnects. Metal diffusion bonding for high-thermal-conductivity die attach. Wafer-level packaging with integrated antenna and waveguide structures.

Bond Quality & Metrology

Post-bond metrology includes scanning acoustic microscopy (SAM) for void detection, IR transmission imaging for bond interface inspection, tensile/shear testing for bond strength verification per MIL-STD-883, and cross-section SEM for bond interface microstructure analysis.

Need Wafer Bonding Services?

Specify your wafer materials, bonding type, and cavity/hermeticity requirements — our team will respond with a detailed quotation within 24 hours.

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