Vertical Memory Contact Plugs for Staircase Word Line Exposure
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Solution Overview
Problem
In the manufacturing of vertical non-volatile memory devices, the formation of staircase-shaped word line pads can lead to pattern loading effects, causing contact holes to fail in exposing corresponding word line pads, resulting in poor electrical contact and deteriorated electrical characteristics.
Innovation Solution
The implementation of a vertical memory device design featuring conductive gate electrodes stacked on a substrate with channel structures and conductive contact plugs extending vertically to ensure electrical contact with the gate electrodes, where the contact plugs are formed to different depths and spacings to prevent pattern loading effects, allowing for uniform contact and improved electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If contact holes are formed on staircase-shaped word line pads, then integration density is enhanced, but pattern loading effects cause contact holes to fail exposing corresponding word line pads
Solution Approach 1:
The contact plugs are divided into multiple segments at different depths: first contact plugs contact first gate electrodes at certain depths, while second contact plugs contact a second gate electrode at a different depth. This segmentation allows each contact plug to be independently positioned to avoid pattern loading effects and ensure proper exposure of the corresponding gate electrode.
Solution Approach 2:
The solution transitions from a two-dimensional planar contact structure to a three-dimensional vertical structure by extending contact plugs to different depths. The first contact plugs extend to a first depth and the second contact plugs extend to a second depth, creating a vertical dimension that resolves the exposure problem caused by the staircase shape.
2Reliability
If contact holes are formed to expose word line pads, then electrical contact is achieved, but pattern loading effects deteriorate electrical characteristics
Solution Approach 1:
Different contact plugs are given different local qualities in terms of depth and positioning. The first contact plugs are positioned to contact first gate electrodes at specific depths, while second contact plugs are positioned to contact the second gate electrode at a different depth. This local differentiation ensures that each contact plug optimally contacts its corresponding gate electrode without being affected by pattern loading effects from adjacent structures.
3Ease of manufacture
If uniform contact plugs are formed, then manufacturing is simplified, but pattern loading effects prevent proper exposure of gate electrodes
Solution Approach 1:
The contact plug structure is made dynamic by allowing different contact plugs to have different depths and positions. The first contact plugs extend to a first depth while second contact plugs extend to a second depth, enabling the structure to adapt to the varying depths of the staircase-shaped gate electrodes and ensure proper exposure without compromising manufacturing feasibility.
Data Source
AI summary
A vertical memory device includes a plurality of gate electrodes at a plurality of levels, respectively, spaced apart from each other in a vertical direction substantially perpendicular to a top surface of a substrate, a channel extending in the vertical direction on the substrate and penetrating through the gate electrodes, and a plurality of contact plugs extending in the vertical direction and contacting the gate electrodes, respectively. At least one second contact plug is formed on a first gate electrode among the plurality of gate electrodes, and extends in the vertical direction.