Dual Shadow Mask Capacitor Design for Leakage Reduction
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Solution Overview
Problem
The shadow mask deposition process in semiconductor manufacturing faces limitations in achieving small electrode sizes due to mask and deposition defects, leading to high leakage current and low yield, necessitating the use of costly photolithography techniques for high-resolution products.
Innovation Solution
A dual shadow mask design is employed to create capacitor structures with small effective areas by overlapping top and bottom electrode patterns, allowing for smaller capacitance areas without reducing the size of the shadow mask openings, thereby simplifying the fabrication process and reducing leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If shadow mask deposition process is used to create small electrode patterns, then fabrication simplicity and cost-effectiveness are improved, but manufacturing precision deteriorates due to mask and deposition defects
Solution Approach 1:
The patent divides the single shadow mask process into two separate shadow mask processes: first shadow mask for bottom electrode and second shadow mask for top electrode. This segmentation allows each mask to be optimized independently, with the second mask specifically designed to compensate for deposition defects, thereby improving manufacturing precision while maintaining the simplicity of shadow mask fabrication
Solution Approach 2:
The first shadow mask process is performed preliminarily to create the bottom electrode pattern, establishing a foundation for the subsequent second shadow mask process. This preliminary action allows the second mask to focus specifically on correcting deposition defects and achieving precise overlapping, improving overall pattern precision without sacrificing fabrication simplicity
2Area of moving object
If shadow mask openings are reduced to achieve small electrode sizes, then electrode area is improved, but manufacturing precision deteriorates due to deposition and testing difficulties
Solution Approach 1:
The patent transitions from controlling electrode size through single-dimension mask opening reduction to a two-dimensional approach using overlapping areas of two separately deposited electrode patterns. This dimensional change allows small effective capacitor areas to be achieved through geometric overlap rather than through difficult small opening fabrication, thereby maintaining manufacturing precision while achieving small electrode sizes
3Manufacturing precision
If photolithography is used to achieve high resolution, then manufacturing precision is improved, but device complexity and fabrication cost increase
Solution Approach 1:
The patent employs disposable shadow masks that can be easily fabricated and discarded, replacing expensive and complex photolithography processes. The shadow masks are simple structures that can be created using basic fabrication techniques, and their temporary use in the deposition process provides high precision electrode patterns without the complexity and cost of photolithography equipment and materials
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 production of capacitor structures with effective capacitance areas of a few microns square or less, improving yield and reducing fabrication costs by avoiding the need for photolithography, while allowing for the testing of dielectric performance and process conditions.
Implementation Method 1
a shadow mask is placed over the substrate surface. The substrate with the shadow mask is then subjected to a deposition process of a conductive material. The substrate areas corresponding to the aperture openings of the shadow mask receive a deposition coating while other areas are shielded by the shadow mask
Implementation Method 2
The substrate with the shadow mask is then subjected to a deposition process of a conductive material
Data Source
AI summary
Dual shadow mask design can overcome the size and resolution limitations of shadow masks to provide capacitor structures with small effective areas. The capacitor structures have bottom and top electrode layers patterned using shadow masks, sandwiching a dielectric layer. The effective areas of the capacitors are the overlapping areas of the top and bottom electrodes, thus allowing small area sizes without subjected to the size limitation of the electrodes. The dual shadow mask design can be used in conjunction with high productivity combinatorial processes for screening and optimizing dielectric materials and fabrication processes.