Multilayer Mask Capacitor Openings for High-Aspect-Ratio DRAM
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Solution Overview
Problem
The increased aspect ratio of the lower electrode in semiconductor devices complicates the control of the opening of the support structure pattern, making it difficult to form the dielectric material of the capacitor, which is a limiting factor for further integration and performance improvement.
Innovation Solution
A multilayer mask is used to form an open region with a major axis to minor axis ratio greater than 1.5, allowing for complete formation of the capacitor dielectric layer and improving the semiconductor device's performance and operational reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the aspect ratio of the lower electrode is increased to maintain integration density, then the unit cell area is reduced, but the opening of the support structure pattern becomes difficult to control
Solution Approach 1:
The patent divides the mask structure into multiple layers (first mask layer, second mask layer, third mask layer) with different functions. The first mask layer defines the initial pattern, the second mask layer creates the support structure opening, and the third mask layer forms the capacitor opening. This segmentation allows independent optimization of each layer's thickness and material properties to achieve precise opening control despite high aspect ratios.
Solution Approach 2:
The patent transitions from a single-layer mask approach to a multi-layer mask approach, adding the vertical dimension of mask layering to solve the opening control problem. By stacking multiple mask layers with different thicknesses and materials, the system gains additional degrees of freedom to control the etching process and achieve precise opening dimensions.
2Reliability
If the opening of the support structure pattern is reduced to maintain capacitance, then the aspect ratio increases, but the dielectric material formation becomes difficult
Solution Approach 1:
The patent segments the dielectric material formation process into multiple steps corresponding to different mask layers. The first dielectric layer is formed through the first mask layer opening, and the second dielectric layer is formed through the second mask layer opening. This segmentation allows each dielectric layer to be optimized independently for its specific function and formation conditions.
Solution Approach 2:
The patent performs preliminary actions by forming the support structure pattern and its opening before forming the capacitor dielectric layers. The support structure opening is created in advance to provide a template that guides subsequent dielectric material deposition, ensuring proper alignment and facilitating the formation process even with high aspect ratios.
3Device complexity
If a single-layer mask is used to form the open region, then the process is simpler, but the ratio of major axis to minor axis cannot be greater than 1.5
Solution Approach 1:
The patent uses three separate mask layers to achieve the elliptical shape with a major axis to minor axis ratio greater than 1.5. The first mask layer creates the basic pattern, the second mask layer refines the support structure opening, and the third mask layer defines the final capacitor opening shape. This segmentation enables precise control of the elliptical geometry that would be impossible with a single-layer mask.
Solution Approach 2:
The patent changes the parameters of each mask layer, including thickness, material composition, and pattern dimensions, to achieve the desired elliptical shape. By independently adjusting the parameters of each mask layer, the system can optimize the opening shape ratio while maintaining processability and manufacturing feasibility.
Data Source
AI summary
A semiconductor device and a method of manufacturing a semiconductor device are provided. The semiconductor device includes a substrate, a plurality of lower electrodes disposed on the substrate, and at least one support structure pattern supporting the plurality of lower electrodes. The at least one support structure pattern define an open region having a first dimension along a first direction and a second dimension along a second direction. A ratio of the second dimension to the first dimension is greater than 1.5.