Wafer Tester Preheating Control for Lot Change Downtime

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Solution Overview

Problem

Wafer testing devices experience unstable temperatures when idle for long periods, leading to inaccurate measurements and increased preheating times, which in turn increase the total measuring time for each wafer lot, resulting in reduced productivity.

Innovation Solution

A preheating control system that includes a processor with a timing circuit to calculate the lot-changing time and a controlling circuit to determine whether to perform device preheating based on this time compared to a standard lot-changing time, thereby optimizing preheating only when necessary.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the wafer testing device performs device preheating whenever a wafer lot is inserted, then the device temperature stability is improved, but the total measuring time increases and productivity decreases

Engineering Contradiction:

Improvedevice temperature stabilityVSAvoidwafer testing productivity

Core Design Contradiction:

Stability of the object's compositionVSProductivity

Solution Approach 1:

The preheating control method dynamically adjusts preheating operations based on real-time lot-changing time calculations. The system continuously monitors the time between wafer lot removal and insertion, and only initiates preheating when the lot-changing time exceeds a predetermined threshold, thereby optimizing the balance between temperature stability and productivity

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the parameter of preheating operation from a fixed always-on mode to a conditional mode based on lot-changing time. By using the lot-changing time as a control parameter, the system determines whether preheating is necessary, thus reducing unnecessary preheating operations that would increase testing time

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If the wafer testing device performs device preheating whenever a wafer lot is inserted, then the measurement accuracy is improved, but the wafer testing time increases

Engineering Contradiction:

Improvemeasurement accuracyVSAvoidwafer testing time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system implements feedback control by calculating the actual lot-changing time and comparing it against the predetermined threshold. This feedback mechanism ensures that preheating is only performed when necessary, thereby maintaining measurement accuracy while minimizing time loss from unnecessary preheating operations

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS12332279B2Preheating control system, preheating control method and non-transient computer readable storage medium

Publication Date: 2025.06.17 NAN YA TECH

AI summary

A preheating control system comprising a testing device and a processor is provided in present disclosure. The testing device is configured to perform a wafer testing on a wafer lot and perform a device preheating on the testing device. The processor is coupled to the testing device and comprises a timing circuit and a controlling circuit. The timing circuit is configured to calculate a lot-changing time, wherein the lot-changing time is a difference between a time corresponding to removal of a previous wafer lot from the testing device and a time corresponding to insertion of the wafer lot into the testing device. The controlling circuit is configured to control the testing device to perform the wafer testing, and configured to control the testing device to perform the device preheating according to the lot-changing time and a standard lot-changing time.