Mask Layer Boron Density Control for High Aspect Ratio Etching
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Solution Overview
Problem
In semiconductor device manufacturing, forming holes with high aspect ratios is challenging due to mask shape deterioration during etching, which affects the precision and consistency of hole formation in stacked bodies, especially as the number of layers increases and the thickness of the stacked body grows.
Innovation Solution
A method involving a mask layer with regions of varying boron or carbon density, made from metals like tungsten, is used for dry etching, which helps maintain the shape integrity of the mask and prevents shoulder drops during etching, allowing for precise formation of holes with reduced diameter variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of stacked layers is increased to achieve high bit density, then the storage capacity is improved, but the stacked body becomes thicker and the aspect ratio of holes increases, causing mask shape deterioration
Solution Approach 1:
The mask layer is designed with non-uniform composition, containing regions with different densities of boron or carbon atoms. This local variation in material properties allows different regions of the mask to have different etching resistance characteristics, enabling the mask to maintain its shape during deep etching processes required for high aspect ratio holes in thick stacked bodies.
Solution Approach 2:
The invention changes the compositional parameters of the mask layer by controlling the density distribution of boron or carbon atoms. By adjusting these atomic density parameters in different regions of the mask layer, the etching resistance is optimized to prevent mask shape deterioration during the etching of high aspect ratio holes through thick stacked bodies.
2Quantity of substance
If dry etching is performed on thick stacked bodies to form high aspect ratio holes, then the storage capacity is improved, but the mask shape deteriorates and shoulder drops occur
Solution Approach 1:
The mask layer incorporates regions with non-uniform boron or carbon density to create localized variations in etching resistance. This allows the mask to resist shape deterioration and prevent shoulder drops during the dry etching process, maintaining precise hole formation even when etching through thick stacked bodies for high storage capacity.
Solution Approach 2:
The mask layer is formed as a composite material containing metal (tungsten, tantalum, zirconium, hafnium, molybdenum, niobium, ruthenium, osmium, rhenium, or iridium) combined with boron or carbon atoms in non-uniform densities. This composite structure provides enhanced etching resistance and shape stability during the dry etching of high aspect ratio holes through thick stacked bodies.
3Stability of the object's composition
If the mask layer thickness is increased to maintain shape during etching, then the mask shape stability is improved, but the etching precision and hole diameter control deteriorate
Solution Approach 1:
Instead of uniformly increasing mask thickness, the invention creates local quality variations within the mask layer by controlling boron or carbon density distribution. This allows the mask to achieve sufficient shape stability during etching while maintaining precise hole diameter control, as the non-uniform composition provides differential etching resistance rather than relying on increased thickness.
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 formation of memory holes with straight side walls and reduced diameter variation, improving memory cell characteristics and maintaining the shape precision of the mask layer, even at high aspect ratios and increased layer thickness.
Implementation Method 1
performing dry etching on the layer to be etched using the patterned mask layer
Data Source
AI summary
A method for manufacturing a semiconductor device includes forming a mask layer including a) one metal from tungsten, tantalum, zirconium, hafnium, molybdenum, niobium, ruthenium, osmium, rhenium, and iridium, b) boron, and c) carbon on a layer to be etched. The mask layer is patterned. A hole or a groove is formed in the layer to be etched by performing dry etching on the layer to be etched using the patterned mask layer. The mask layer includes a first region and a second region. The first region includes boron and the second region includes boron such that a density of boron in the second region is different from a density of boron in the first region, or the first region includes carbon and the second region includes carbon such that a density of carbon in the second region is different from a density of carbon in the first region.