Optical Interference Wafer Temperature Measurement Using Phase Angle
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Solution Overview
Problem
Existing methods for measuring wafer temperature during semiconductor manufacturing processes are inadequate, particularly when the wafer temperature deviates from the temperature of the wafer stage, leading to instability in processing.
Innovation Solution
A measuring apparatus using optical interference to directly measure wafer temperature by analyzing the phase angle of complex amplitudes in interference spectra, employing a light source, spectrometer, and calculator to calculate temperature changes based on phase angle correlations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If indirect measurement methods (measuring wafer stage temperature) are used, then measurement simplicity is maintained, but measurement precision deteriorates when wafer temperature deviates from stage temperature
Solution Approach 1:
The patent replaces mechanical/physical contact temperature sensors with optical interference measurement. A light source emits light through the wafer, and a detector measures optical interference patterns that encode temperature information. This substitutes direct physical measurement with optical field-based measurement, enabling non-contact temperature sensing that directly measures wafer temperature without requiring thermal equilibrium with the wafer stage.
Solution Approach 2:
The patent introduces optical interference patterns as an intermediary carrier of temperature information. Instead of directly sensing temperature, the system uses light waves that interact with the wafer and encode temperature data through interference patterns. The detector measures these patterns, and a processor decodes temperature information, creating an indirect but accurate measurement chain that avoids direct thermal contact requirements.
2Manufacturing precision
If conventional temperature measurement methods are used, then process stability is maintained, but manufacturing precision deteriorates due to temperature deviations
Solution Approach 1:
The patent implements real-time temperature feedback through continuous optical interference measurement. The system measures wafer temperature at multiple points during the manufacturing process and provides feedback to control systems. This enables dynamic adjustment of process parameters to compensate for temperature variations, ensuring consistent manufacturing precision while improving reliability through continuous monitoring and correction.
3Measurement precision
If direct wafer temperature measurement is implemented, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent designs the optical measurement system to serve multiple functions: temperature measurement, wafer positioning, and process monitoring. The same light source and detector infrastructure used for optical interference temperature sensing can also support other measurement and control operations. This multi-functionality reduces overall system complexity by consolidating measurement capabilities rather than requiring separate dedicated systems for each function.
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 precise and direct measurement of wafer temperature during processing, improving process stability by accurately tracking temperature changes and reducing errors from noise components.
Implementation Method 1
A method of measuring a wafer temperature using optical interference is known
Implementation Method 2
measure a spectroscopic spectrum waveform of light generated by reflecting the measurement light from the measurement target object
Implementation Method 3
perform Fourier transform of the spectroscopic spectrum waveform
Data Source
AI summary
A measuring apparatus according to one embodiment includes a light source, a spectrometer, and a calculator. The light source emits measurement light. The spectrometer measures a spectroscopic spectrum waveform of light. The calculator is configured to: perform Fourier transform of the spectroscopic spectrum waveform; extract a waveform; calculate a phase angle at an amplitude peak position of the extracted waveform; calculate a temperature or thickness change amount based on the change amount of the phase angle; and calculate a temperature by adding the temperature change amount to a reference temperature, or calculate a thickness of the measurement target object by adding the thickness change amount to a reference thickness.