1. Incoming Wafer Inspection and Sorting

Before wafers even enter the front-end process line, they are received in lots from suppliers—often in FOSBs or open cassettes. At this stage, a wafer sorter performs:

● Wafer unpacking and re-cassette loading into FOUPs or clean cassettes

● Wafer ID reading and mapping

● Notch or flat alignment

● Defect or missing wafer detection

This ensures that every wafer entering the fab is traceable, properly oriented, and loaded into a tool-compatible carrier, minimizing risk during the initial processing stages.

2. Lot Splitting and Merging in Lithography and Etch

In front-end process steps such as lithography, etching, and deposition, it’s common to split or merge lots for different process conditions. Wafer sorters at these nodes help:

● Divide a lot into smaller batches for customized treatments

● Merge lots after parallel process steps

● Verify wafer IDs and sequence before tool entry

● Handle temporary reordering to align wafers by process priority

These capabilities ensure that wafers receive the right process at the right time, while maintaining correct MES tracking.

LAMINA SORTER L201 (For Taiko Wafer)

3. Metrology and Inline Inspection Interface

After critical process steps, wafers must be inspected. Wafer sorters provide the link between process tools and metrology systems, performing:

● Wafer transfer between FOUPs and inspection cassettes

● Reordering wafers based on inspection logic

● OCR or barcode-based verification

● Flipping wafers if frontside inspection is required

The sorter ensures that inspection tools receive wafers in the expected format and sequence, helping to maintain accurate data collection and lot integrity.

4. Inter-Tool Transfer and Buffering

Between tools in front-end or mid-end processing, wafer sorters can act as intermediate buffers or format converters. Key roles here include:

● Re-aligning wafers between incompatible tools

● Transferring wafers between different cassette types (e.g., FOUP ↔ open cassette)

● Staging wafers temporarily during tool maintenance or recipe adjustments

● Reordering wafers to meet recipe-specific sequencing rules

Bridge sorters are particularly valuable in these scenarios, supporting multiple cassette standards and wafer sizes.

5. Transition from Front-End to Back-End (Mid-End)

As wafers exit front-end processing (typically at the completion of metal layers or passivation), they may undergo bumping, thinning, or dicing before packaging. Sorters at this junction help:

● Repackage wafers into back-end-compatible carriers

● Recheck wafer IDs and lot structure

● Mark wafers with new tracking data if needed

● Transfer from FOUPs to tape frames or custom carriers in advanced packaging lines

This transition point is critical—without proper sorting, wafers may be lost or mishandled between facilities or processing zones.

6. Final Quality Control and Shipment Preparation

At the end of the process chain, wafers—now known as known good dies (KGDs) or tested units—must be prepared for shipping. Wafer sorters ensure:

● Final mapping and classification of wafers

● Exclusion of defective units based on test results

● Packaging into shipping cassettes or trays

● Lot documentation updates and MES closure

This step protects final yield and ensures traceability for customers and downstream packaging partners.

Sorter Customized (Packaging Machine)

Conclusion

Wafer sorters are not just auxiliary tools—they are important assets embedded at every major transition in the semiconductor process. From initial receiving to front-end lot control, from mid-end tool bridging to final shipment, sorters ensure accurate wafer identification, orientation, and flow control.

Fortrend’s advanced wafer sorters are designed to support the full semiconductor manufacturing cycle—offering integration with MES systems, precision alignment, ID verification, and flexible carrier compatibility. Contact our team to learn how we can help optimize your process chain from start to finish.