Positional Deviation Measuring Device for Wafer Warp Compensation
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Solution Overview
Problem
In the lithography process for semiconductor devices, positional deviation measurements can be affected by wafer warping, leading to errors in alignment due to the inclination of the wafer relative to the optical axis, which existing methods fail to accurately account for.
Innovation Solution
A positional deviation measuring device that adjusts the refracting angle of incident light and detects reflected light from a substrate at multiple angles, allowing for the calculation of positional deviation between upper and lower-layer patterns by solving simultaneous equations derived from varying incident angles or wavelengths, thereby accounting for wafer warping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single incident angle is used for measurement, then the measurement process is simple, but measurement precision deteriorates due to wafer warping errors
Solution Approach 1:
The measurement process is segmented into multiple independent measurements at different incident angles. By dividing the single measurement into N measurements with different incident angles (θ1, θ2, ..., θN), the system can separately capture the effects of alignment deviation and wafer warping, then solve for both parameters simultaneously using the segmented data set.
Solution Approach 2:
The measurement is extended from a single incident angle (one-dimensional) to multiple incident angles (multi-dimensional). By adding the dimension of varying incident angles, the system gains additional independent equations that enable simultaneous determination of both alignment deviation and wafer warping parameters, resolving the underdetermined system.
2Measurement precision
If multiple incident angles are used, then measurement precision improves by accounting for wafer warping, but device complexity increases
Solution Approach 1:
The incident angle parameter is systematically varied across N different values (θ1, θ2, ..., θN). By changing this physical parameter and measuring the corresponding reflected light intensity variations, the system creates a set of equations that can be solved to extract both alignment deviation and wafer warping information, transforming a complex measurement problem into a solvable parameter identification problem.
3Reliability
If wafer warping is not accounted for, then the measurement process is straightforward, but reliability of alignment measurement deteriorates
Solution Approach 1:
The system uses the measured reflected light intensities at multiple incident angles as feedback to iteratively solve for both alignment deviation and wafer warping parameters. The feedback loop allows the system to adjust and refine the calculated parameters until convergence, ensuring reliable measurement results that account for wafer warping effects.
Solution Approach 2:
The system performs preliminary measurements at multiple incident angles before calculating the final alignment deviation. By collecting all necessary measurement data first and then performing the simultaneous solution, the system ensures that wafer warping effects are properly accounted for in the final alignment measurement, improving 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 approach reduces errors in alignment deviation measurements by accurately determining the positional deviation and wafer warp, even when the refractive indices and film thickness are unknown, ensuring precise alignment of semiconductor patterns.
Implementation Method 1
an adjusting unit for adjusting a refracting angle of incident light with respect to a substrate
Implementation Method 2
a detector for detecting reflected lights from the substrate
Data Source
AI summary
According to one embodiment, an adjusting unit adjusts a refracting angle of incident light with respect to a substrate, a detector detects reflected light from the substrate, and a calculating unit calculates positional deviation of the pattern based on patterns respectively reflected in reflected lights obtained from the incident light generating N number of refracting angles with respect to the substrate, where N is an integer of two or greater.