Telecentric Converter Lens for Lithography Alignment
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Solution Overview
Problem
Current lithographic apparatuses face challenges in achieving high accuracy and low variation in substrate alignment during the formation of different layers, which is crucial for precise pattern transfer in IC manufacturing.
Innovation Solution
A pre-alignment system is introduced, featuring a common object lens group that produces telecentricity in the object space and a multipath sensory array with a telecentric converter lens to ensure telecentricity in the image space, along with a detector to create pre-alignment signals from diffracted beams, facilitating accurate positioning of the patterning device and substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional alignment systems are used, then the device complexity is lower, but the alignment accuracy and consistency vary with working distance
Solution Approach 1:
The optical system is segmented into distinct functional modules: a common object lens group for object space telecentricity, multiple independent image lens systems for different measurement channels, and telecentric converter lenses for image space telecentricity. Each module can be optimized independently while contributing to the overall alignment accuracy.
Solution Approach 2:
Telecentric converter lenses are introduced as intermediary optical elements between the image lens systems and detectors. These converters act as mediators that transform non-telecentric image spaces into telecentric ones, ensuring consistent magnification across different working distances without requiring complete redesign of the entire optical system.
2Manufacturing precision
If telecentric converters are added to achieve consistent magnification, then the alignment accuracy improves, but the device complexity increases
Solution Approach 1:
The telecentric converter lenses serve multiple functions: they provide image space telecentricity, maintain consistent magnification across different working distances, and work with multiple image lens systems simultaneously. This multi-functionality reduces the need for separate correction mechanisms for each lens system.
Solution Approach 2:
The optical system utilizes parameter changes in the telecentric converter lenses, specifically varying their focal lengths and positions, to maintain consistent magnification across different working distances. By adjusting these parameters, the system achieves precise pattern transfer without requiring complex mechanical adjustment mechanisms.
3Adaptability or versatility
If multiple image lens systems are used for different measurement channels, then the alignment capability is enhanced, but the device complexity increases
Solution Approach 1:
Multiple image lens systems are merged around a single common object lens group, sharing the telecentric object space. This merging approach allows different measurement channels to benefit from the same high-precision object space telecentricity while maintaining their independent image space optimization through individual telecentric converters.
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 solution enhances alignment accuracy and reduces variation, enabling precise exposure and pattern transfer by maintaining consistent magnification and eliminating perspective errors across different working distances.
Implementation Method 1
a common object lens group configured to collect diffracted beams from the patterning device
Implementation Method 2
the common object lens group is further configured to produce telecentricity in an object space of the pre-alignment system
Implementation Method 3
a telecentric converter lens configured to produce telecentricity in an image space of the pre-alignment system
Implementation Method 4
a detector for each of the at least one image lens system, wherein the detector is configured to create a pre-alignment signal based on the diffracted beams
Data Source
AI summary
A pre-alignment system includes a common object lens group configured to collect diffracted beams from a patterning device, wherein the common object lens group is further configured to produce telecentricity in an object space of the pre-alignment system. The pre-alignment system also includes a multipath sensory array having at least one image lens system, wherein the at least one image lens system includes a telecentric converter lens configured to produce telecentricity in an image space of the pre-alignment system.