Wafer Prober Chuck Calibration Using a Reference Temperature Probe
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Solution Overview
Problem
Existing calibration methods for chuck temperature in wafer probers lack precision and accuracy, particularly under actual chip test conditions, and are costly and time-consuming, with conventional methods failing to achieve the required temperature accuracy of 0.1°C or below.
Innovation Solution
A calibration device with a calibration card and integrated calibration temperature probe that allows for precise, automated calibration of chuck temperature under the same environmental conditions as chip testing, eliminating manual errors and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a measuring wafer with multiple temperature sensors is used for calibration, then temperature distribution can be displayed, but measurement precision is limited due to sensor deviations and cost is very high
Solution Approach 1:
The patent uses a single reference temperature sensor instead of multiple sensors on a measuring wafer. This reference sensor is used in conjunction with compensation tables to determine temperatures at multiple positions, thereby copying the function of multiple sensors through a single sensor and computational compensation, reducing cost while maintaining measurement precision
Solution Approach 2:
The patent replaces the physical measuring wafer with multiple sensors with a computational approach using a single reference sensor and compensation tables. The mechanical/system complexity of multiple sensors is substituted with software-based temperature calculation methods, reducing manufacturing cost while achieving the same measurement objectives
2Ease of manufacture
If a single drop sensor is placed at various temperature measurement points, then cost is reduced, but measurement precision decreases due to manual attachment inaccuracy and measurement time increases
Solution Approach 1:
The patent implements automated calibration where the system performs self-calibration using the reference temperature sensor and pre-stored compensation tables. The automated temperature determination process eliminates manual sensor placement and calculation, thereby maintaining measurement precision while reducing cost and time
Solution Approach 2:
The patent pre-calculates and stores compensation tables before actual temperature measurements. These compensation tables contain pre-determined correction values that are stored in memory, allowing the system to quickly and accurately determine temperatures at various positions without manual intervention during the measurement process
3Measurement precision
If calibration is performed with a measuring wafer, then temperature distribution is displayed, but the accuracy does not reflect actual chip test conditions since the wafer is placed far from the calibration location
Solution Approach 1:
The patent places the reference temperature sensor at the exact location where chip tests are performed, rather than using a separate measuring wafer. This ensures that the calibration is performed under identical local conditions as the actual testing, thereby achieving temperature accuracy that truly reflects test conditions without increasing overall system complexity
4Ease of manufacture
If manual entry of measured values into compensation tables is performed, then calibration can be completed, but productivity decreases due to time-consuming manual processes
Solution Approach 1:
The patent replaces manual entry of measured values with automated data processing. The system automatically reads temperature data from the reference sensor, retrieves the appropriate compensation table, and calculates the temperature at the chip location using stored algorithms, thereby eliminating time-consuming manual operations and significantly increasing calibration productivity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate, continuous monitoring and precise control of chuck temperature during testing, ensuring high precision and reducing the need for expensive measuring wafers and manual processes.
Implementation Method 1
a calibration temperature probe (60, 61) attached to the calibration card (6), which can be approached by the chuck (3) via the position controller (350) in a calibration mode such that the calibration temperature probe (60, 61) can detect a current temperature at different positions on the surface (O) of the chuck (3)
Implementation Method 2
Chuck 3 can be temperature-controlled to a user-defined target temperature via a temperature controller 300 using a heating element (not shown) and a cooling element (not shown)
Implementation Method 3
The cooling element is used, in particular, to achieve temperatures below room temperature
Implementation Method 4
A temperature probe S0 is located inside Chuck 3 to detect and output the current Chuck temperature
Data Source
Figure 1a
Figure 1b
Figure 2
AI summary
The present invention develops a calibration arrangement and a corresponding calibration method for calibrating a chuck, and a calibration apparatus. The calibration apparatus is equipped with a calibration card (6) attachable in or on an insertion opening (E) of a wafer prober (1), a corresponding substantially closed space being formed when the calibration card (6) is attached; a calibration temperature probe (60, 61) which is attached to the calibration card (6), a chuck (3) for clamping the wafer (4), which chuck can be brought to an enterable intended temperature by a temperature controller (300) and is displaceable in lateral directions (x, y) and in the height direction (z) by means of a position controller (350), being able to home in on the calibration temperature probe by means of the position controller (350) such that the calibration temperature probe (60, 61) can measure a respective current temperature at different positions on the surface (O) of the chuck (3) or on the surface (O') of a wafer (4) clamped thereon; and an evaluation device (600) which is connectable to the calibration temperature probe (60, 61), the temperature controller (300) and the position controller (350) and which is configured to calibrate the temperature output values of the one or more temperature probes (S1-S9) on the basis of the current temperatures at the different positions as measured by the calibration temperature probe (60, 61).