Optical Charge Probe for Wet Semiconductor Substrate Processing
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Solution Overview
Problem
Existing methods for measuring electrostatic charge during semiconductor device manufacturing are indirect and inaccurate, leading to defects due to static electricity.
Innovation Solution
A substrate processing apparatus equipped with a probe featuring an electro-optical crystal and a reflective mirror, which changes optical refractive index in response to electric fields, allowing for accurate measurement of electrostatic charge on semiconductor substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If indirect measurement methods are used to estimate electrostatic charge based on film quality distribution, then the measurement process is simple, but the measurement accuracy is low
Solution Approach 1:
The patent replaces indirect mechanical/electrical measurement methods with optical measurement. The probe uses optical fields to detect electrostatic charge through the electro-optical crystal, which changes its optical properties in response to electric fields. This substitution of measurement domain (from electrical/mechanical to optical) enables direct, accurate measurement without complex contact-based systems.
Solution Approach 2:
The electro-optical crystal serves as an intermediary between the electrostatic charge on the substrate and the measurement system. The crystal's optical refractive index changes in response to the electric field from the charge, allowing the charge to be measured indirectly through optical property changes while maintaining direct measurement capability and high accuracy.
2Measurement precision
If electro-optical crystal with reflective mirror is used in the probe, then the measurement accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent combines the reflective mirror directly with the electro-optical crystal by forming the mirror on the crystal surface. This integration merges two components (crystal and mirror) into a single unified structure, reducing the number of separate parts while maintaining the functional benefits of both the electro-optical sensing and the optical reflection capabilities.
Solution Approach 2:
The patent utilizes changes in the optical parameters (refractive index) of the electro-optical crystal in response to electric fields. By measuring changes in optical properties rather than using complex electrical measurement circuits, the system achieves high measurement accuracy with a relatively simple probe structure.
3Measurement precision
If direct measurement of electrostatic charge is implemented, then the accuracy is improved, but the difficulty of detecting and measuring increases
Solution Approach 1:
The patent replaces difficult electrical measurement techniques with optical measurement methods. The optical probe detects electrostatic charge through changes in the electro-optical crystal's refractive index, converting an difficult-to-measure electrical quantity into an easily measurable optical property change.
Solution Approach 2:
The electro-optical crystal acts as a mediator that translates electrostatic charge information into optical signal changes. This intermediary conversion makes the detection process simpler and more accurate, as optical measurements are generally easier to perform with high precision than direct electrical measurements of static charge.
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
The apparatus enables precise measurement and control of electrostatic charge, reducing defects and improving the accuracy of semiconductor device manufacturing processes.
Implementation Method 1
an electro-optical crystal having an optical refractive index configured to change in proportion to a magnitude of an electric field applied at an upper portion of a semiconductor substrate
Data Source
AI summary
A substrate processing apparatus includes: a chamber configured to perform a wet process and having an internal space, a chuck in the internal spaced and being configured for loading a semiconductor substrate thereon, a probe having an end above the chuck and including an electro-optical crystal and a reflective mirror on one surface of the electro-optical crystal, a measuring unit connected to the probe and configured to provide reference light to the probe, and to detect a polarization component of reflected light reflected from the one end of the probe by the reference light, and a controller configured to calculate an amount of electrostatic charge on a surface of the semiconductor substrate from the polarization component.