Hierarchical Correction Map for EUV Mask Dose Control
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Solution Overview
Problem
The existing electron beam lithography techniques face challenges in performing real-time dose correction calculations due to large data sizes and inefficiencies in processing correction information, particularly for EUV masks with small influence radii, which require extensive processing time and are not suitable for parallel distributed processing.
Innovation Solution
A charged particle beam drawing apparatus that utilizes a hierarchical correction map structure, dividing correction data into subframes and blocks with varying mesh sizes, allowing for efficient data conversion and processing by generating shot data for each block, thereby reducing memory requirements and improving processing speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If correction information is stored in a map format with fine mesh size (50 nm to 100 nm) to achieve high manufacturing precision for EUV masks, then the data size becomes extremely large, making it difficult to transfer and process efficiently
Solution Approach 1:
The correction map is divided into multiple tile maps, each covering a specific region of the drawing area. This segmentation reduces the data size that needs to be transferred and processed at once, while maintaining the fine mesh resolution (50 nm to 100 nm) needed for EUV mask proximity effect correction. The tile maps can be processed independently and in parallel.
Solution Approach 2:
The patent introduces a hierarchical data structure with multiple levels: the drawing area is divided into regions, each region contains multiple tiles, and each tile contains correction data at different mesh sizes. This multi-dimensional organization transforms the flat large-scale map into a structured hierarchy, enabling efficient storage, transfer, and processing while preserving the high-resolution correction information where needed.
2Manufacturing precision
If the correction calculation is performed in real-time within the drawing apparatus, then the processing time becomes excessively long due to the huge amount of calculation required for fine mesh correction, reducing productivity
Solution Approach 1:
The correction maps are pre-calculated using external computing resources before the actual drawing process. The pre-calculated correction data is then stored in a database and quickly retrieved during drawing operations. This separates the computationally intensive correction calculation from the time-sensitive drawing execution, enabling both high accuracy and fast processing.
Solution Approach 2:
The patent introduces a database as an intermediary between the correction calculation system and the drawing apparatus. The database stores the pre-calculated correction maps and provides efficient retrieval during drawing operations. This intermediary layer decouples the calculation and drawing processes, allowing them to operate independently and optimally.
3Manufacturing precision
If correction information is stored in a single large data file, then the data structure becomes difficult to process in parallel, reducing processing efficiency
Solution Approach 1:
The single large correction data file is segmented into multiple smaller tile map files, each representing a specific region of the drawing area. This segmentation enables parallel processing of different tiles by multiple computing units simultaneously, while maintaining the完整性 of the overall correction information through proper organization and indexing of the tile files.
4Manufacturing precision
If the mesh size is reduced to 50 nm to 100 nm for EUV mask proximity effect correction, then the manufacturing precision is improved, but the calculation time increases significantly
Solution Approach 1:
The high-resolution correction maps (50 nm to 100 nm mesh size) are calculated in advance using external computing resources before the drawing process. This preliminary calculation eliminates the time penalty during actual drawing operations, as the correction data is simply retrieved and applied rather than calculated in real-time.
Solution Approach 2:
The patent creates a copy of the correction information in a pre-processed format stored in a database. Instead of performing repeated calculations during drawing, the system uses the pre-calculated correction map copies, which contain all the necessary correction data for different regions and conditions, enabling fast retrieval and application during the drawing process.
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 enables efficient data processing and reduces the memory needed for calculations, allowing for faster and more accurate drawing of semiconductor patterns by distributing correction data in a hierarchical format that can be processed in real-time, improving overall data processing efficiency.
Implementation Method 1
a drawing unit for drawing a pattern in a drawing area on a substrate... using an electron beam drawing apparatus
Implementation Method 2
a proximity effect has an influence radius of about 10 μm... In the inside of the drawing apparatus, to suppress a dimensional change due to an influence of the above, a dose correction calculation is performed in realtime
Implementation Method 3
a fogging effect or a loading effect has an influence radius of a few millimeters
Implementation Method 4
a fogging effect or a loading effect has an influence radius of a few millimeters
Data Source
AI summary
In one embodiment, a charged particle beam drawing apparatus includes a drawing unit that draws a pattern in a drawing area on a substrate and a control processing circuitry that controls the drawing unit via a process including receiving drawing data with a hierarchical correction map input to the control processing circuitry. The drawing data with the hierarchical map includes a plurality of files in which division maps are respectively described in files in units of subframes. Each division map includes dose correction information associated with corresponding one of blocks of the drawing area. The process further includes generating shot data by performing a data conversion process on the drawing data, reading a division map corresponding to a block in the area to be drawn from the hierarchical correction map, calculating a dose, and controlling the drawing unit based on the shot data and the calculated dose.