Radiation Spot Center Determination Using Reflected Beam Detection
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Solution Overview
Problem
In lithographic processes, the accurate determination of the center of a radiation spot on a surface is challenging due to manufacturing tolerances and unknown tilt angles, leading to inaccuracies in measurement results.
Innovation Solution
A method involving a sensor with a radiation source and detector that emits and receives radiation beams to determine the center of the radiation spot by measuring the target's position and using additional positions and optical interaction parameters, with optional calibration object rotations to enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If manufacturing tolerances and calibration variations are present in the sensor system, then the device can be manufactured more easily and cost-effectively, but the location of the center of the radiation spot becomes unknown leading to measurement inaccuracies
Solution Approach 1:
The patent replaces mechanical alignment and centering procedures with an optical measurement system. A radiation spot is emitted onto the substrate surface, and its center position is determined optically by detecting the reflected radiation pattern. This substitution eliminates the need for precise mechanical manufacturing and alignment, allowing standard manufacturing tolerances while achieving accurate center positioning through optical detection.
2Measurement precision
If the center of the radiation spot is determined using additional measurement positions and calibration object rotations, then the measurement precision is improved, but the measurement time and process complexity increase
Solution Approach 1:
The patent performs preliminary calibration by determining the center of the radiation spot using multiple measurement positions and calibration object rotations before actual substrate measurements. This preliminary action establishes accurate center positioning and calibration data that can be reused for subsequent measurements, avoiding the need to repeat the time-consuming multi-position calibration process for each measurement.
3Measurement precision
If the center of the radiation spot is determined using multiple measurement positions and calibration procedures, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent implements a universal calibration and measurement system where the same radiation source and detector assembly serves multiple functions: emitting radiation spots, detecting reflected patterns, determining center positions, and performing substrate measurements. The calibration object can be rotated to multiple positions using the same stage mechanism used for substrate measurement, eliminating the need for separate calibration devices and reducing overall system complexity.
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 method allows for precise determination of the radiation spot's center, improving measurement accuracy and enabling more accurate calibration and patterning on substrates.
Implementation Method 1
emitting, with the radiation source, a first emitted radiation beam onto the surface to create the radiation spot on the surface... receiving, with the detector, a first reflected radiation beam at least comprising radiation from the radiation spot reflected by the target
Data Source
AI summary
A method for determining a center of a radiation spot irradiated on a surface by a sensor, the sensor including a radiation source and a detector. The method includes: emitting, with the radiation source, a first emitted radiation beam onto the surface to create the radiation spot on the surface, wherein at least a part of a target arranged at the surface is irradiated by the radiation spot; receiving, with the detector, a first reflected radiation beam at least including radiation from the radiation spot reflected by the target; detecting the presence of the target based on the first reflected radiation beam; determining a first measured position of the target based on the first reflected radiation beam; and determining a center of the radiation spot as projected on the surface in at least a first direction based on the first measured position of the target.