This article outlines the typical wafer sorter workflow, key functions at each stage, and best practices to ensure safe and efficient use of the system.

1. System Initialization and Environment Check

Before beginning any wafer sorting operation, the system must be properly initialized:

● Power-On Sequence: The wafer sorter is powered on, and internal diagnostics are run to check system status.

● Environmental Monitoring: Temperature, humidity, and cleanroom compatibility are verified. Any particle monitoring sensors are activated.

● Cassette & FOUP Readiness: Load ports are cleared, and the system checks for correct cassette types (e.g., FOUP, open cassette) and mechanical integrity.

Once the system is ready, operators can proceed with cassette loading.

2. Cassette Loading and Verification

Operators manually or automatically place wafer cassettes onto the load ports. The sorter then performs the following:

● Cassette ID Recognition: Reads cassette barcode or RFID tag.

● Cassette Condition Check: Ensures the cassette is not damaged and is properly seated.

● Wafer Presence Detection: Using sensors or mapping tools, the sorter scans each slot to detect the presence and absence of wafers.

● Wafer Orientation Check: Determines notch or flat alignment for proper downstream handling.

This step ensures the system has a clear picture of the initial wafer layout before sorting begins.

3. Wafer ID Reading and Mapping

Each wafer in the cassette undergoes identification and mapping:

● OCR or Laser ID Reading: Wafer IDs etched or marked on the surface are captured and recorded.

● Wafer Mapping: The system creates a digital map showing wafer presence, slot numbers, and status (missing, broken, or misaligned wafers).

● Error Handling: Any unreadable IDs, misaligned wafers, or contaminated surfaces are flagged for operator review or automatic rejection.

These steps support traceability and ensure wafers are correctly handled and tracked.

4. Sorting and Transfer Operations

Based on preloaded recipes or instructions from the MES system, the sorter executes one or more of the following operations:

● Cassette-to-Cassette Transfer: Moves wafers from the source cassette to the destination in the same or a different order.

● Recipe-Based Sorting: Rearranges wafers based on criteria such as process lot, test results, or inspection status.

● Wafer Flipping: Some systems can flip wafers when required for specific process steps.

● Aligning for Next Process: Aligns wafers to a specific notch orientation or tool requirement.

The system's robotic arm or linear actuator handles wafers gently, maintaining a particle-free and damage-free environment.

5. Completion and Data Logging

After sorting is complete, the system performs final steps:

● Final Mapping: Verifies the final position and condition of each wafer in the destination cassette.

● Data Upload: Transfers wafer IDs, slot positions, and process records to the fab’s MES or data management system.

● Cassette Release: The sorted cassettes are released to the operator or automatically transferred to the next station.

Logs of the entire process, including any alarms or handling errors, are stored for quality control and traceability.

6. Routine Maintenance and Cleanliness Protocol

To ensure continuous performance, operators and engineers must follow best practices:

● Scheduled Cleaning: Regular cleaning of wafer contact surfaces, robotic arms, and sensors using lint-free wipes and approved solvents.

● HEPA Filter Checks: For sorters with internal filtration, filters must be checked and replaced periodically.

● Calibration and Alignment: Periodic verification of wafer alignment and ID reading accuracy is essential.

Conclusion

Understanding the standard workflow and operating procedures of a wafer sorter is critical to maintaining efficient, clean, and traceable wafer movement in semiconductor fabs. From cassette loading and wafer ID reading to recipe-driven sorting and final transfer, each step is optimized to minimize human error and maximize production reliability.

As wafer processing continues to advance in complexity and volume, the wafer sorter remains an indispensable bridge between tools — quietly ensuring that each wafer moves to the right place, at the right time, with the right orientation.

Looking for a Smarter Wafer Sorting Solution?

At Fortrend, we specialize in high-precision wafer sorters designed to meet the rigorous demands of semiconductor fabs. Our systems offer reliable ID reading, flexible sorting recipes, and contamination-free handling—all while supporting seamless integration with your fab’s automation and MES infrastructure.

Contact Fortrend today to learn how our wafer sorting solutions can improve your workflow efficiency, traceability, and yield.