Wafer Bonding

晶沐光电 combines wafer grinding/polishing/thinning and laser processing to provide homogeneous/heterogeneous, permanent/temporary wafer bonding. High vacuum sealing, heat/pressure and surface activation create reliable interfaces for3D integration, advanced packaging, MEMS, power, RF and optoelectronic devices, including custom small batches for institutes. Referenced processes/equipment include single-wafer cleaning, class100 cleanroom bonding and KSB-H1000. Permanent bonding irreversibly joins wafers/chips into strong, hermetic, reliable structures. Direct bonding uses ultracleaning, plasma activation and CMP, room-temperature van der Waals prebonding and annealed Si-O-Si covalent bonds: no interlayer, high strength/hermeticity/insulation, void-free/low-stress interfaces for Si/Si, Si/SiO2 and Si/SOI. Anodic bonding uses heat/high electric field for silicon–glass chemical bonds, near-bulk strength, low leak rate and stable sealed cavities, such as Si/borosilicate. Eutectic bonding melts/diffuses Au-Sn, Cu-Sn, In or Au-Si interlayers, yielding low-temperature, conductive, thermally conductive, reliable bonds with broad process windows for Cu/Au/Sn-coated wafers. Thermocompression uses heat/precise pressure for solder-free metal-atom diffusion, high interconnect density/low interface resistance, and direct bonding of Si, metal-coated, compound-semiconductor, sapphire, glass, SiC or ceramic wafers. Hybrid bonding simultaneously joins copper/dielectric for integrated mechanical/electrical submicron-pitch connections, high bandwidth, low latency/loss and HBM/AI stacking in3D NAND, HBM, AI processors, high-end Chiplets and VLSI wafers. Examples are sapphire/Si, SiO2/sapphire and GaAs/Si. Temporary bonding glues a wafer/chip to a carrier for backside processing then gentle release. Thermal-slide bonding softens thermoplastics, PPC or polyimides with heat, hardens on cooling and reheats/slides for release; it resists heat/chemicals for Si thinning, TSV and advanced packaging, but needs heating and may leave adhesive. UV release cures for strength then shortwave UV degrades/debonds UV-release adhesive/double-sided tape: gentle room-temperature release for heat-sensitive MEMS, CIS, compound and ultrathin wafers, but needs a transparent carrier and has moderate heat resistance. Laser release uses transparent carriers and an absorbing layer to decompose/release adhesive without contact; laser-responsive coating plus bonding adhesive gives stress-free, residue-free, precise release for large ultrathin3D IC/HBM/Chiplet/advanced-packaging wafers, at high equipment/material cost. Low-melting In, SnBi or AuSn alloys bond molten and remelt for release; high heat tolerance/conductivity and acid/alkali resistance suit SiC/GaN power devices/high-temperature processes, but metal residue is difficult to clean and processing is complex. Bondable materials include Si, SiC, GaN, sapphire, GaAs, InP, quartz/borosilicate glass, alumina/aluminum-nitride ceramics, diamond, bonded composites, SOI, lithium tantalate/niobate and coated wafers.

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