Passivation Layer Opening Equipment Passivation layer opening equipment is a critical tool in semiconductor manufacturing, used to selectively remove passivation layers from wafer surfaces to expose underlying conductive regions for subsequent processes such as bonding, probing, or metallization. The passivation layer, typically made of silicon nitride (SiN), silicon dioxide (SiO₂), or polyimide, protects the wafer from contamination, moisture, and mechanical damage during fabrication. However, precise openings must be created to enable electrical connections or testing. Key Functions and Components 1. Laser Ablation System: - A high-precision laser (e.g., UV or green laser) is commonly used to remove the passivation layer with minimal thermal damage to the substrate. - The system includes beam shaping optics, galvanometer scanners, and real-time monitoring to ensure accuracy. 2. Plasma Etching Module: - For finer or larger-scale openings, plasma etching (dry or reactive ion etching) is employed to selectively remove the passivation material. - Gas chemistry (e.g., CF₄, O₂) is optimized for different passivation materials. 3. Photolithography-Assisted Opening: - In some cases, photolithography defines the opening pattern, followed by wet or dry etching to remove the exposed passivation layer. 4. Alignment and Inspection Systems: - High-resolution cameras and pattern recognition software align the equipment with wafer features. - Post-processing inspection ensures opening dimensions meet specifications (e.g., via optical or electron microscopy). Process Workflow 1. Wafer Loading: Automated handling systems position the wafer. 2. Alignment: The system aligns to fiducial marks or circuit patterns. 3. Opening Formation: Laser or plasma removes the passivation layer in predefined areas. 4. Cleaning: Residues are removed using chemical or plasma cleaning. 5. Inspection: Quality control checks for defects or misalignment. Applications - Wafer-Level Packaging (WLP): Creating bond pads for flip-chip or wire bonding. - Probe Testing: Exposing test pads for electrical validation. - Advanced Packaging (e.g., Fan-Out WLP, 3D ICs): Enabling vertical interconnects. Technical Challenges - Precision: Sub-micron accuracy is required for advanced nodes. - Material Selectivity: Avoiding damage to underlying metals or dielectrics. - Throughput: Balancing speed with accuracy for high-volume production. Conclusion Passivation layer opening equipment is indispensable in semiconductor manufacturing, combining laser, plasma, and photolithography technologies to enable reliable interconnects. Its performance directly impacts yield and device functionality, making it a cornerstone of modern IC fabrication.