VNAND Support Structures for Straight Word Line Cuts
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Solution Overview
Problem
In the manufacturing of VNAND flash memory devices, the etching process for forming word line cuts is influenced by dummy channels, leading to bent word line cuts and potential electrical shorts between gate electrodes, causing reliability failures such as electrical shorts.
Innovation Solution
A vertical memory device design featuring a gate electrode structure with a staircase shape, support structures, and a method of manufacturing that includes forming a mold with sacrificial and insulation layers, and using support structures to prevent the mold from leaning or falling, ensuring straight openings and separated gate electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If dummy channels are formed through the mold together with the channel to prevent the mold from falling down, then the mold stability is improved, but the etching process for forming word line cuts is influenced causing bent word line cuts and potential electrical shorts between gate electrodes
Solution Approach 1:
The patent removes dummy channels from the mold structure after the mold has been formed and stabilized. By extracting the dummy channels at an appropriate stage, the mold maintains its stability during formation while preventing the harmful effect of bent word line cuts during subsequent etching processes.
Solution Approach 2:
The patent forms dummy channels preliminarily to stabilize the mold during the forming process, then removes them before the word line cut etching process. This preliminary stabilization followed by removal prevents both mold collapse and electrical shorting issues.
2Strength
If dummy channels are formed through the mold to support the mold structure, then the mold support is improved, but the word line cuts may bend toward the dummy channel causing gate electrode electrical connection
Solution Approach 1:
The dummy channels are extracted from the mold structure after serving their support function. This removal eliminates the distortion effect on word line cuts while maintaining the mold support strength during the critical forming stages.
Solution Approach 2:
The dummy channels are formed preliminarily to provide mold support during construction, then removed before the precision etching of word line cuts. This timing ensures both mold strength and cutting precision are achieved.
3Stability of the object's composition
If the mold is formed with high stability using dummy channels, then the mold integrity is improved, but the etching process complexity increases due to the need to avoid dummy channel interference
Solution Approach 1:
By removing dummy channels before the word line cut etching process, the patent simplifies the etching process by eliminating the need to navigate around dummy channel structures, while maintaining mold integrity during the forming stages.
Solution Approach 2:
The dummy channels are preliminarily formed to ensure mold integrity, then removed before the complex etching process. This preliminary stabilization followed by removal reduces etching process complexity by eliminating interference elements.
Data Source
AI summary
A vertical memory device includes a gate electrode structure formed on a substrate including a cell array region and a pad region, a channel, contact plugs, and support structures. The gate electrode structure includes gate electrodes extending in a second direction and stacked in a staircase shape in a first direction on the pad region. The channel extends through the gate electrode structure on the cell array region. The contact plugs contact corresponding ones of steps, respectively, of the gate electrode structure. The support structures extend through the corresponding ones of the steps, respectively, and extend in the first direction on the pad region. The support structure includes a filling pattern and an etch stop pattern covering a sidewall and a bottom surface thereof. An upper surface of each of the support structures is higher than that of the channel.