Lithography Mask Alignment Precision via Mapping Marks
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Solution Overview
Problem
Current photolithography processes face challenges in achieving precise alignment and mapping of masks during the semiconductor manufacturing process, leading to poor alignment accuracy and increased scan failure rates, which affects the quality and yield of the lithography process.
Innovation Solution
The lithography process system employs a scanner device with adjusting and exposing devices to align and map masks with high precision, using align and mapping marks to adjust the mask position to within 135 nm of the predetermined position, and includes a cleaning device to maintain mask cleanliness, thereby improving inspection quality and reducing scan failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional photolithography alignment methods are used, then the process is simple, but alignment accuracy deteriorates leading to poor mask alignment precision
Solution Approach 1:
The system performs preliminary mapping of the mask using mapping marks before the actual exposing process. This preliminary action establishes a reference framework that enables high-precision alignment during exposure, resolving the contradiction by preparing alignment data in advance rather than during the critical exposing step
Solution Approach 2:
Mapping marks serve as intermediary elements between the mask and the substrate alignment system. These marks enable indirect measurement and adjustment of mask position, achieving high alignment accuracy without requiring direct complex measurement of the entire mask structure
2Manufacturing precision
If conventional mask positioning is used, then the process is fast, but alignment precision deteriorates resulting in scan failures
Solution Approach 1:
The alignment process is segmented into distinct phases: mapping mark detection, coordinate transformation calculation, and final positioning adjustment. This segmentation allows automated computation of transformation parameters, achieving both high precision and efficiency by separating measurement from execution
Solution Approach 2:
The system uses mapping marks to detect actual mask position, compares it with the predetermined position, calculates transformation parameters, and applies feedback adjustments. This closed-loop feedback mechanism ensures high positioning precision while maintaining scan efficiency through automated parameter calculation
3Reliability
If mask inspection is performed frequently, then quality control improves, but productivity decreases due to additional processing time
Solution Approach 1:
Mask mapping and initial inspection are performed as preliminary actions before the main exposing process. This allows quality verification to be integrated into the workflow without adding separate inspection steps, maintaining both high reliability and productivity
Solution Approach 2:
The system merges the alignment and inspection functions into a single integrated process using mapping marks. The same mapping marks used for alignment also serve as inspection references, combining two quality control activities into one operation to maintain throughput while ensuring quality
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 enhances the precision of mask alignment and mapping, decreases scan failure rates, improves the quality of the exposing process, increases yield, and reduces costs by maintaining mask cleanliness and improving storage efficiency.
Implementation Method 1
the source light is generated to expose a photoresist layer on the substrate via the mask
Data Source
AI summary
A system is provided. The system includes an exposing device configured to generate a real-time image, including multiple first align marks, of a mask and an adjusting device configured to adjust an off-set of the mask from a pre-determined position to be smaller than a minimum aligning distance according to the first align marks and multiple align marks on a substrate, and further to move the mask closer to the pre-determined position to have a displacement, less than a minimum mapping distance, from the pre-determined position according to the real-time image and a reference image of the mask.