Nonvolatile Storage Device Sacrifice Layer Etching
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Solution Overview
Problem
The manufacturing of crosspoint nonvolatile storage devices faces challenges due to tapering of storage layers during processing, leading to electrical shorts and variations in device characteristics, primarily caused by the reverse-tapered shape of interlayer insulating films and residual materials between word lines.
Innovation Solution
A method involving the use of a sacrifice layer with a higher etching rate than the mask layer, allowing for precise processing of storage units into columnar shapes and complete removal of the sacrifice layer without damaging the mask layer, thereby preventing electrical shorts and maintaining device integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If etching processing is performed to form interlayer insulating film, then the insulating film is formed between storage layers, but the reverse-tapered shape causes residual cell material to remain and creates electrical shorts
Solution Approach 1:
The patent segments the removal process into multiple stages: first removing exposed cell material, then removing the interlayer insulating film, and finally removing residual material. This multi-stage segmentation ensures complete removal without electrical shorts while maintaining manufacturing precision.
Solution Approach 2:
The patent performs preliminary actions by first forming the interlayer insulating film with reverse-tapered shape, then systematically removing exposed cell material before proceeding to film removal. This preliminary material removal prevents electrical shorts during subsequent processing steps.
2Ease of manufacture
If storage layer is processed into tapered shape, then processing is simplified, but the taper creates shading that leaves residual material and causes electrical shorts
Solution Approach 1:
The patent converts the harmful shading effect of the tapered storage layer into a beneficial process feature. The taper is intentionally used to control the removal sequence, where the tapered shape naturally guides the etching process to remove material in a specific pattern that prevents electrical shorts while maintaining processing simplicity.
Solution Approach 2:
The patent segments the removal process into distinct stages: removing exposed cell material first, then removing the interlayer insulating film, and finally removing residual material. This segmentation allows the tapered shape to be utilized effectively without causing electrical shorts.
3Ease of manufacture
If interlayer insulating film is buried in reverse-tapered trench, then film formation is facilitated, but the reverse-tapered shape creates shading that prevents complete material removal
Solution Approach 1:
The patent performs preliminary removal of exposed cell material before removing the interlayer insulating film. This preliminary action ensures that when the film is removed, no residual cell material remains that could cause electrical shorts, achieving complete material removal while maintaining ease of manufacture.
Solution Approach 2:
The patent segments the removal process into multiple stages: first removing exposed cell material, then removing the interlayer insulating film, and finally removing residual material. This segmentation allows the reverse-tapered film to be formed easily while ensuring complete material removal through systematic multi-stage processing.
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 method reduces processing failures and increases yield by ensuring complete removal of the sacrifice layer and preventing shorts between word lines, maintaining the integrity of the storage units and improving the overall performance of the nonvolatile storage devices.
Implementation Method 1
removing the sacrifice layer to expose the first storage unit film having been covered with the sacrifice layer
Data Source
AI summary
Manufacturing a nonvolatile storage device including: stacking a first electrode film forming a first electrode and a first storage unit film forming a first storage unit on a substrate; processing the first electrode film and the first storage unit film into a strip shape; burying a sacrifice layer between the processed first electrode films and between the processed first storage unit films; forming a second electrode film forming a second electrode on the first storage unit film and the sacrifice layer; forming a mask layer on the second electrode film; processing the second electrode film into a strip shape using the mask layer; removing a portion of the first storage unit film exposed from the sacrifice layer using the mask layer processing the first storage unit film into a columnar shape, removing the sacrifice layer exposing the first storage unit film; and removing the exposed first storage unit film.