Alignment Microscope Beam Splitting for Precise Mask-to-Workpiece Imaging
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Solution Overview
Problem
Existing alignment technologies in semiconductor manufacturing face challenges in achieving high accuracy for aligning mask and workpiece patterns due to limitations in imaging and aberration correction, which affect exposure precision.
Innovation Solution
A detection apparatus incorporating a beam splitter with a sandwich structure and aberration correction lenses is used to split and correct optical paths for mask and workpiece marks, enabling precise imaging and positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional beam splitter is used to split optical paths for mask and workpiece marks, then the alignment process can be performed, but imaging accuracy and alignment precision are insufficient
Solution Approach 1:
The optical path is segmented into separate paths for mask mark and workpiece mark using a beam splitter, allowing independent optimization of each path. The beam splitter divides the incident light into reflected and transmitted beams, enabling simultaneous imaging of both marks without optical interference.
Solution Approach 2:
Aberration correction lenses are introduced to change the optical parameters of each path. These lenses compensate for optical aberrations by adjusting the focal length and curvature of the optical path, thereby improving imaging accuracy and alignment precision for both mask and workpiece marks.
2Measurement precision
If aberration correction lenses are added to improve imaging accuracy, then alignment precision improves, but device complexity increases
Solution Approach 1:
The aberration correction lenses are designed to serve multiple functions: they correct optical aberrations for both the mask mark path and workpiece mark path simultaneously. This multi-functional design improves imaging accuracy without proportionally increasing device complexity.
Solution Approach 2:
The aberration correction lenses act as intermediary elements between the beam splitter and the imaging unit. They mediate the optical path by compensating for aberrations introduced by the beam splitter and other optical components, thereby improving overall system performance.
3Reliability
If the light-splitting surface is sandwiched between two members with different surface directions, then stable light splitting is achieved, but manufacturing difficulty increases
Solution Approach 1:
The beam splitter employs asymmetric surface directions for the first and second members. The light-splitting surface is oriented at a specific angle relative to the first member, while the second member has a different orientation. This asymmetric configuration ensures stable light splitting by preventing resonance and maximizing the difference in optical paths.
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 configuration allows for high-accuracy alignment of mask and workpiece patterns, enhancing exposure precision and improving manufacturing quality.
Implementation Method 1
a light-splitting surface that splits each of the first light and the second light
Implementation Method 2
one or more aberration correction lenses that are disposed in the first optical path and the second optical path
Data Source
AI summary
A detection apparatus includes: an alignment microscope that captures an image of a mask mark and an image of a workpiece mark; and a position detector that detects a position of the mask mark and a position of the workpiece mark on the basis of those images. The alignment microscope includes an imaging unit, a beam splitter that splits each of the first light and the second light, and one or more aberration correction lenses. The beam splitter includes first and second members connected to each other with a light-splitting surface being sandwiched therebetween. All of first and second incident surfaces and emission surfaces are configured to have different surface directions with respect to the light-splitting surface. The one or more aberration correction lenses includes a first aberration correction lens disposed in a first optical path and a second aberration correction lens disposed in a second optical path.