As semiconductor fabs continue to increase automation and traceability requirements, wafer sorters have evolved from simple transfer tools into highly configurable systems capable of executing complex wafer-handling logic. At the center of this flexibility lies recipe programming—the ability to define how wafers should be sorted, reordered, inspected, or routed based on production needs.

This article introduces the fundamentals of recipe programming in wafer sorters, including sorting rules, ID-based logic, process-driven classification, and how these functions support modern manufacturing.

1. What Is Recipe Programming in Wafer Sorters?

Recipe programming refers to the customizable logic that dictates how a wafer sorter handles wafers.

A recipe determines:

● How wafers move between carriers

● In what sequence they should be arranged

● Which wafers require inspection or ID checks

● How the tool responds to mapping or ID mismatches

● Rules for binning, grouping, and process classification

In essence, the recipe is the “digital instruction set” that transforms a wafer sorter into a versatile automation platform.

2. Sorting by Slot Number (Sequential Logic)

The most common sorting method is slot-based sequencing, often used to reorder wafers before or after processing.

Examples of sequential sorting:

● Ascending or descending order (1→25, 25→1)

● Gap removal (compacting wafers from partially filled carriers)

● Custom sequences (e.g., 1-5 to FOUP A, 6-10 to FOUP B)

When it’s used:

● Preparing lots for tools that require strict order

● Standardizing wafer flow between departments

● Removing cross-slotted or misaligned wafers

Sequential logic is the foundation of nearly every wafer sorting operation.

3. Sorting by Wafer ID (OCR-Driven Logic)

With traceability becoming critical, many fabs rely on ID-based sorting using OCR or laser-mark reading.

ID-based recipe functions include:

● Grouping wafers by ID prefix (product type, batch number, customer code)

● Matching wafers to MES-specified lists

● Separating wafers with unreadable or mismatched IDs

● Identifying duplicate IDs

Use cases:

● Post-incoming inspection

● Wafers from multiple suppliers or customers

● High-mix production environments

ID logic ensures every wafer is accounted for throughout the process flow.

4. Sorting by Process Classification

Sorters can classify wafers based on process status, quality bin, or fab workflow, enabling advanced routing and batch preparation.

Common classification categories:

● Pre-process vs. post-process

● Tested vs. untested wafers

● Good bin vs. reject bin

● Product type or technology node

● Different process recipes or tool families

Typical applications:

● Preparing wafers for metrology or electrical testing

● Separating engineering lots from production lots

● Creating recipe-specific sub-batches for downstream tools

Process classification makes the sorter a strategic control point in fabs.

5. Advanced Recipe Options

Modern wafer sorters offer additional programming tools:

● Mapping logic: reject wafers detected as broken, cross-slotted, or missing

● Carrier logic: define rules for FOUP-to-FOUP, FOUP-to-open cassette, or mixed configurations

● Exception handling: define how the tool reacts to ID errors, slot mismatches, or mapping anomalies

● Data logging: integrate recipe results with MES or host systems

● Parallel actions: simultaneous carrier preparation, aligner operation, and ID reading

These features allow fabs to standardize workflows and minimize human intervention.

Conclusion

Recipe programming transforms wafer sorters into highly adaptable automation platforms capable of supporting diverse production flows. Whether sorting by sequence, ID, or process category, recipe logic ensures wafers move through the fab cleanly, safely, and with complete traceability. As manufacturing grows more complex, intelligent recipe management becomes key to efficiency, yield control, and streamlined operations.

If your fab is exploring advanced recipe programming or upgrading wafer sorting automation, Fortrend offers high-precision wafer sorters designed for flexible logic control, stable performance, and seamless integration with MES and host systems.

To learn more about our automation solutions or request a customized configuration, contact Fortrend today—our engineering team is ready to support your manufacturing needs.