Electrostatic Chuck Thermometer Thermal Drift Compensation
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Solution Overview
Problem
High-throughput and high-accuracy measurement in semiconductor device inspection using charged particle radiation apparatuses are compromised due to thermal deformation caused by temperature differences between the specimen and the electrostatic chuck, with existing methods failing to simultaneously achieve both high-throughput and accuracy.
Innovation Solution
Incorporating a thermometer to measure the temperature of the electrostatic chuck and using a control device to adjust the measurement or inspection timing based on this data, allowing for accurate thermal deformation compensation without direct contact, thus enabling high-throughput and high-accuracy measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the measurement is started after waiting for thermal deformation to be eliminated, then measurement accuracy is improved, but productivity deteriorates due to increased standby time
Solution Approach 1:
The system performs preliminary temperature measurement of the electrostatic chuck before the actual measurement begins. The control device uses this temperature information to determine the appropriate measurement onset time, allowing the system to prepare in advance and eliminate thermal deformation effects before measurement starts, thereby achieving both high accuracy and high throughput
Solution Approach 2:
The system implements a feedback mechanism where the temperature of the electrostatic chuck is continuously monitored and fed back to the control device. Based on this feedback, the control device dynamically adjusts the measurement onset time to ensure measurements are performed only when thermal deformation has been eliminated, optimizing both accuracy and productivity
2Measurement precision
If the thermometer is brought into direct contact with the specimen, then temperature measurement accuracy is improved, but measurement reliability deteriorates due to potential fluctuation
Solution Approach 1:
The system uses the electrostatic chuck as an intermediary object to measure the specimen's temperature indirectly. The thermometer contacts the electrostatic chuck rather than the specimen directly, and the control device calculates the specimen temperature based on the chuck temperature and thermal conduction relationships, thereby avoiding potential fluctuation while maintaining measurement accuracy
Solution Approach 2:
The system creates a thermal model that copies the relationship between the electrostatic chuck and specimen. By measuring the chuck temperature and using the pre-established thermal conduction model, the system can accurately determine specimen temperature without direct contact, ensuring both accuracy and reliability
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
This configuration allows for high-throughput and high-accuracy measurements by ensuring proper measurement onset times based on temperature conditions, reducing image drift and maintaining resolution and reproducibility in semiconductor device inspections.
Implementation Method 1
an electrostatic chuck mechanism for holding a specimen with electrostatic attraction
Implementation Method 2
a thermometer which measures the temperature of the electrostatic chuck
Implementation Method 3
When a temperature difference exists between a beam irradiation subject by the charged particle radiation apparatus and a specimen stage for mounting the beam irradiation subject, the specimen is thermally deformed
Data Source
AI summary
The present invention provides a high-throughput scanning electron microscope in which a wafer (9) is held by an electrostatic chuck (10), an image is obtained using an electron beam, and the wafer surface is measured, wherein even in a case where the temperature of the wafer (9) is changed due to the environmental temperature the electron scanning microscope is capable of preventing any loss in resolution or the deterioration of the measurement reproducibility caused by thermal shrinkage accompanied by temperature change of the wafer (9). A drill hole is provided on the rear surface of the electrostatic chuck (10), and a thermometer (34) is secured in place so that the front end is brought into elastic contact with the bottom surface of the drill hole. The output of the thermometer (34) is sent to a computing unit, the computing unit computes a measurement limit time for beginning measurement, based on a predetermined algorithm, from an output value of the thermometer (34), and measuring begins at individual measurement sites after the measurement limit time has elapsed.