Mask Pattern Formation Using Stacked Organic Inorganic Layers
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Solution Overview
Problem
As semiconductor device integration increases, finer pattern features and line widths are difficult to achieve due to optical limitations and optical proximity effects, leading to challenges in forming mask patterns with precise etch resistance during the photolithography process.
Innovation Solution
A method involving a double exposure technique using a stacked organic and inorganic mask layer structure, where the inorganic mask layer is etched to different thicknesses in defined regions, and the organic mask layer is exposed and removed to form a mask pattern, allowing for precise formation of fine line widths and feature sizes, and optionally using a multilayered inorganic mask structure for improved adhesiveness and etch selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithography is used to form patterns, then the process is simple, but optical limitations and optical proximity effects prevent achieving fine line widths and feature sizes
Solution Approach 1:
The mask layer is divided into multiple segments: an organic mask layer and an inorganic mask layer stacked on the substrate. This segmentation allows each layer to serve different functions - the organic layer provides etch resistance while the inorganic layer enables precise pattern formation, thereby achieving fine line widths without compromising process simplicity
Solution Approach 2:
The patent uses a composite mask structure combining organic and inorganic materials. The organic mask layer (e.g., photoresist) and inorganic mask layer (e.g., silicon oxide or silicon nitride) work together to overcome the limitations of single-material masks, providing both etch resistance and optical precision for fine feature formation
2Reliability
If a single mask layer is used, then the process is simple, but etch resistance is insufficient for thick material layers
Solution Approach 1:
The mask system is segmented into an organic mask layer and an inorganic mask layer with distinct functions. The organic layer provides the primary etch resistance barrier for thick material layers, while the inorganic layer provides additional protection and pattern definition, ensuring reliable etching without requiring excessive mask thickness that would compromise pattern fidelity
Solution Approach 2:
Different regions of the mask structure have different properties optimized for their specific functions. The organic mask layer has high etch resistance for the etching process, while the inorganic mask layer has appropriate thickness and composition for pattern definition and adhesion, allowing each material to excel at its designated task
3Adaptability or versatility
If the inorganic mask layer is etched to different thicknesses in different regions, then etch selectivity is improved, but the process complexity increases
Solution Approach 1:
The inorganic mask layer is formed with spatially varying thickness - thicker in regions requiring higher etch resistance and thinner in regions where pattern precision is critical. This local variation in thickness provides etch selectivity across different regions of the substrate, allowing the same mask structure to protect different areas with appropriate levels of resistance
Solution Approach 2:
The mask structure is designed to be dynamically adapted to different etching requirements through selective thickness variation. By controlling the deposition or formation process to create non-uniform thickness, the mask automatically provides the appropriate etch resistance profile needed for complex patterning without requiring multiple separate mask layers
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 minimizes corner distortion in fine openings, enabling the formation of mask patterns with precise quadrangular shapes that closely follow the intended design, improving etch resistance and adhesiveness, and simplifying the mask pattern formation process.
Implementation Method 1
The inorganic mask layer may be etched in the first region to a first predetermined thickness, and may be etched in the second region to a second predetermined thickness
Implementation Method 2
The organic mask layer exposed in the third region may be removed to form a mask pattern
Data Source
AI summary
A method of forming a mask pattern for fabricating a semiconductor device. A first region and a second region, having an intersecting third region, are defined in the semiconductor substrate. An inorganic mask layer is etched in the first region to a predetermined thickness, and etched in the second region to another predetermined thickness. While the inorganic mask layer is etched in the first and second region, an organic mask layer is exposed in the third region. The organic mask layer exposed in the third region is removed to form a mask pattern. Consequently, double exposure is performed using the organic mask layer and the inorganic mask layer, so that a fine feature size that closely follows a desired layout can be formed, damage to the organic mask layer by ashing is prevented, and adhesiveness between the organic mask layer and the inorganic mask layer can be improved.