Ellipsometer Sample Orientation via Extended Optical Path
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Solution Overview
Problem
Current systems for orienting samples in ellipsometer and similar systems lack effective methods for precise adjustment of vertical position and tilt, which affects the angle and plane of incidence of electromagnetic radiation, limiting their sensitivity and accuracy.
Innovation Solution
The system employs electromagnetic radiation that impinges on samples at both normal and oblique angles, with the path length of oblique angle radiation being extended through focusing and collimating lenses to enhance sensitivity, and uses a single detector with a shutter system to selectively direct radiation, along with intensity modulation by a beam chopper to minimize external light interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the path length of oblique angle radiation is extended through focusing and collimating lenses, then system sensitivity to sample surface height is improved, but device complexity increases
Solution Approach 1:
The optical path is segmented into distinct functional sections: a first focusing lens to concentrate oblique radiation, a collimating lens to parallelize the beam, and a second focusing lens to focus it onto the detector. This segmentation allows each lens to be optimized for its specific function, improving overall system sensitivity while maintaining manageable complexity through modular design
Solution Approach 2:
The patent introduces an extended optical path dimension by routing oblique radiation through a longer sequence of lenses and mirrors before reaching the detector. This dimensional extension of the optical path creates a lever arm effect that amplifies small height changes of the sample surface into larger, more detectable signal variations, thereby improving measurement precision
2Object-affected harmful factors
If a single detector is used with shutter system to selectively direct radiation, then external light interference is minimized, but device complexity increases
Solution Approach 1:
The shutter system operates periodically, opening to allow oblique radiation to reach the detector and closing to block external light interference. This periodic action creates temporal separation between the desired signal and harmful noise, allowing the single detector to distinguish between them based on timing rather than requiring complex spatial filtering
Solution Approach 2:
The shutter acts as an intermediary element between the external environment and the detector. By strategically positioning the shutter in the optical path, it mediates the interaction between external light and the detection system, blocking harmful interference while allowing the oblique radiation signal to pass through when needed
3Loss of information
If electromagnetic radiation is directed at both normal and oblique angles to the sample, then comprehensive alignment information is obtained, but device complexity increases
Solution Approach 1:
The incident radiation is segmented into two distinct angular components: normal incidence radiation for one measurement path and oblique incidence radiation for another path. Each component provides specific alignment information about different aspects of sample orientation, and both are processed separately through dedicated optical paths before reaching the detector
Solution Approach 2:
The single detector serves multiple functions by receiving both normal and oblique radiation signals. Through the shutter system's selective opening, the same detector measures different physical quantities (normal incidence reflectance and oblique incidence reflectance), eliminating the need for separate detectors for each measurement type
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 approach improves the system's sensitivity to sample surface height and allows for precise alignment and data collection in a lit environment without external light interference, enabling accurate ellipsometric data acquisition.
Implementation Method 1
Said electromagnetic radiation which impinges upon said sample at said oblique angle of incidence is caused to pass through focusing and collimating lenses before and after said sample respectively
Implementation Method 2
Said electromagnetic radiation which impinges upon said sample at said oblique angle of incidence is caused to pass through focusing and collimating lenses before and after said sample respectively
Implementation Method 3
intensity modulation by a beam chopper to minimize external light interference
Implementation Method 4
uses a single detector with a shutter system to selectively direct radiation
Implementation Method 5
causing a polarized beam of electromagnetic radiation to impinge on said sample at an oblique angle thereto, interact with said sample and then enter a detector
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
Systems and methodology for orienting vertical position and tilt of samples, applied in ellipsometer and the like systems.