Charged Particle Beam Lithography for Reticle Pattern Formation
Solution Overview
Problem
Conventional optical lithography faces challenges in accurately transferring patterns with features smaller than the light wavelength, requiring complex OPC features like serifs and SRAFs, which increase mask complexity and computational costs, and struggle with precision as process nodes shrink, especially in EUV lithography where imperfections are magnified.
Innovation Solution
A method and system for charged particle beam lithography that uses overlapping shots and dose modulation to optimize reticle pattern formation, allowing for more accurate and efficient creation of patterns with reduced shot count, and employing model-based fracturing to improve dose margin and edge slope, thereby reducing critical dimension variation and line edge roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional optical lithography is used to transfer patterns with features smaller than the light wavelength, then pattern transfer is achieved, but manufacturing precision deteriorates due to diffraction limits and requires complex OPC features
Solution Approach 1:
The patent replaces optical lithography with charged particle beam lithography (electron beam or ion beam). This substitution eliminates the diffraction limit inherent in optical systems, enabling direct writing of sub-wavelength patterns without requiring complex OPC features like serifs and SRAFs. The charged particle beam can be focused to much smaller dimensions, achieving higher manufacturing precision while simplifying the mask design.
Solution Approach 2:
The patent divides the pattern writing process into discrete shots that are sequentially written across the reticle. By using a charged particle beam that can be precisely positioned and controlled, the complex pattern is broken down into manageable shot segments. This segmentation approach enables high precision pattern formation without requiring complex optical proximity correction features, as each shot can be independently optimized.
2Manufacturing precision
If conventional optical lithography with complex OPC features is used, then pattern transfer is achieved, but productivity deteriorates due to increased computational costs and process complexity
Solution Approach 1:
The patent replaces optical lithography with charged particle beam lithography, eliminating the need for complex OPC computational processes. The charged particle beam system directly writes patterns with sub-wavelength precision without requiring iterative optical simulations, proximity effect corrections, or complex mask design computations, thereby significantly improving productivity while maintaining high manufacturing precision.
Solution Approach 2:
The patent performs pattern writing directly with the charged particle beam without requiring preliminary OPC computations or complex mask preparation. The beam parameters and writing conditions are optimized in advance, allowing direct pattern formation on the reticle without iterative computational corrections, thus reducing both computational costs and process time.
3Manufacturing precision
If charged particle beam lithography with overlapping shots is used, then manufacturing precision is improved by reducing critical dimension variation, but use of energy increases due to multiple exposures of the same area
Solution Approach 1:
The patent employs dose modulation where the energy dose of overlapping shots is varied according to the local pattern density and previous exposure history. Areas that have been exposed multiple times receive reduced dose, while newly exposed areas receive full dose. This dynamic parameter adjustment maintains high manufacturing precision by ensuring uniform total dose distribution while minimizing total energy consumption compared to uniform overlapping exposures.
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 the creation of reticles with improved accuracy and reduced manufacturing variations, enhancing the precision of pattern transfer and reducing the need for complex OPC features, thus improving the efficiency and cost-effectiveness of the lithography process, especially at advanced technology nodes.
Implementation Method 1
a lithographic mask or photomask manufactured from a reticle is used to transfer patterns to a substrate such as a semiconductor or silicon wafer
Implementation Method 2
charged particle beam lithography that uses overlapping shots and dose modulation to optimize reticle pattern formation
Data Source
AI summary
A method and system for fracturing or mask data preparation is disclosed in which a desired substrate pattern for a substrate is input. A plurality of charged particle beam shots is then determined which will form a reticle pattern on a reticle, where the reticle pattern will produce a substrate pattern on the substrate using an optical lithography process, wherein the substrate pattern is within a predetermined tolerance of the desired substrate pattern. A similar method and a similar system for forming a pattern on a reticle are also disclosed.