Vertical Memory Device GSL Formation via Insulation Curvature
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Solution Overview
Problem
In VNAND flash memory devices, defects often occur in the GSL (Gate Selection Line) due to incomplete filling of the source gas, leading to unreliable GSL formation.
Innovation Solution
The vertical memory device design includes a gate electrode structure with insulation patterns and channel structures where the lower and upper surfaces of the first insulation pattern are bent away from the substrate, allowing the source gas to completely fill the space for forming the GSL, thereby reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the source gas is used to form the GSL in a conventional vertical NAND structure, then the GSL can be formed, but the source gas cannot completely fill the gap due to structural constraints, leading to defects
Solution Approach 1:
The first insulation pattern is designed with bent upper and lower surfaces that curve away from the substrate, creating a slanted sidewall profile. This curved geometry modifies the gap shape to enable complete source gas filling during GSL formation, eliminating the filling defects that occur in conventional straight-walled structures
Solution Approach 2:
The first insulation pattern exhibits asymmetric thickness distribution, being thicker at the edges and thinner at the center, creating a tapered or slanted sidewall configuration. This asymmetric structure facilitates uniform gas distribution and complete filling of the GSL formation space, resolving the incomplete filling issue in symmetric conventional designs
2Reliability
If the first insulation pattern has bent surfaces away from the substrate, then the source gas can completely fill the GSL formation space, but the insulation pattern structure becomes more complex
Solution Approach 1:
Only the first insulation pattern (the lowermost one) is designed with bent surfaces and slanted sidewalls, while other insulation patterns maintain conventional flat structures. This localized modification applies the complex geometry only where needed for GSL formation, minimizing overall device complexity while achieving complete gas filling
Data Source
AI summary
A vertical memory device includes gate electrodes spaced apart from each other in a first direction. Each of the gate electrodes extends in a second direction. Insulation patterns extend in the second direction between adjacent gate electrodes. A channel structure extends in the first direction. The channel structure extends through at least a portion of the gate electrode structure and at least a portion of the insulation pattern structure. The gate electrode structure includes at least one first gate electrode and a plurality of second gate electrodes sequentially stacked in the first direction on the substrate. Lower and upper surfaces of a first insulation pattern are bent away from the upper surface of the substrate along the first direction. A sidewall connecting the lower and upper surfaces of the first insulation pattern is slanted with respect to the upper surface of the substrate.