Variable Resistance Memory Device Mask Etching Strategy
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Solution Overview
Problem
Conventional manufacturing methods for variable resistance non-volatile memory devices face challenges in miniaturization due to mask pattern stripping, leading to difficulties in forming stable and high-speed switching elements with clear resistance state distinction.
Innovation Solution
The method involves forming a variable resistance non-volatile memory device using a resist mask of line shape, where the second resist mask is wider than the first resist mask, and the hard mask is etched using a two-line shape pattern to reduce non-uniformity and prevent mask pattern stripping, allowing for further miniaturization and stable resistance switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the variable resistance element is miniaturized to improve device density and capacity, then the device capacity increases, but the mask pattern is more likely to be stripped during manufacturing
Solution Approach 1:
The patent divides the single mask formation process into multiple sequential mask formation steps. First, a preliminary mask is formed to define a preliminary pattern, then a final mask is formed to define the precise final pattern. This segmentation allows each mask to be optimized for its specific function, preventing stripping while enabling miniaturization.
Solution Approach 2:
The preliminary mask is formed in advance before the final mask. This preliminary action establishes a base pattern that guides subsequent processing, allowing the final mask to focus only on refining the pattern to the target dimensions without bearing the full burden of pattern definition, thus preventing stripping.
2Device complexity
If a single resist mask is used to form the variable resistance element pattern, then the manufacturing process is simpler, but the etched amounts of variable resistance material layers become non-uniform
Solution Approach 1:
The patent segments the pattern formation into two distinct mask steps: a preliminary mask for rough pattern definition and a final mask for precise pattern refinement. This segmentation allows each mask to be optimized for its specific etching requirements, ensuring uniform etched amounts across the variable resistance material layers.
Solution Approach 2:
The preliminary mask and final mask serve different local functions in the pattern formation process. The preliminary mask provides a base structure, while the final mask provides precise dimensional control. This local differentiation of mask functions enables uniform etching across the entire structure.
3Manufacturing precision
If corner portions of the mask pattern are receded toward the center to form round portions, then the etched amount uniformity is improved, but the mask pattern area is reduced
Solution Approach 1:
The patent segments the mask formation into preliminary and final masks, allowing the final mask to maintain full corner portions for maximum area while the etching process achieves uniformity through the segmented approach. This avoids the need to recede corners.
Solution Approach 2:
Instead of receding corners to achieve uniformity, the patent inverts the approach by maintaining full corners in the mask pattern and achieving uniformity through the segmented mask formation process and controlled etching parameters.
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 miniaturized variable resistance elements with reduced non-uniformity, enhancing the stability and speed of resistance switching while preventing mask pattern stripping, thus improving the performance and capacity of non-volatile memory devices.
Implementation Method 1
a variable resistance layer which is disposed between the first electrode and the second electrode and includes two metal oxide layers which are different in degree of oxygen deficiency
Data Source
AI summary
A method of manufacturing a non-volatile memory device comprises: forming a first electrode layer; a variable resistance material layer, a second electrode layer; and a hard mask layer, forming a first resist mask extending in a first direction on the hard mask layer; forming a first hard mask extending in the first direction by etching the hard mask layer using the first resist mask; forming a second resist mask extending in a second direction, on the first hard mask such that the width of the second resist mask is greater than the width of the first resist mask; forming a second hard mask by etching the first hard mask using the second resist mask; and forming a variable resistance element by patterning, by etching the second electrode layer, the variable resistance material layer and the first electrode layer using the second hard mask.