Stair-Stacked Semiconductor Device Preventing Word Line Bridging
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Solution Overview
Problem
The manufacturing of 3-dimensional nonvolatile memory devices is challenging due to the need for contact plugs of varying depths, which can lead to bridging issues between word lines, complicating the fabrication process.
Innovation Solution
A semiconductor device with insulating layers stacked in a stair-like shape and conductive layers alternately stacked, featuring a first region between upper and lower insulating layers and a second region that protrudes, allowing for increased thickness without increasing the structure's height, thereby preventing bridging by forming undercuts and protruding parts on the sidewalls and surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If contact plugs of various depths are formed to implement 3D stacked structure, then the degree of integration is enhanced, but the manufacturing difficulty increases and bridging occurs between word lines
Solution Approach 1:
The conductive layer is segmented into two distinct regions: a first region with standard thickness positioned between upper and lower insulating layers, and a second region with increased thickness that protrudes between the insulating layers. This segmentation allows contact plugs to be formed at different depths without requiring complex varying-depth fabrication processes, thereby maintaining high degree of integration while simplifying manufacturing.
Solution Approach 2:
The invention transitions from a single-plane conductive layer to a multi-level conductive structure that extends in the vertical dimension. The second region of the conductive layer protrudes between upper and lower insulating layers, creating a three-dimensional arrangement that enables selective contact with stacked word lines at different depths, thus enhancing integration without increasing manufacturing complexity.
2Productivity
If contact plugs of various depths are formed to implement 3D stacked structure, then the degree of integration is enhanced, but bridging occurs between word lines
Solution Approach 1:
The conductive layer is divided into a first region that remains confined between insulating layers and a second region that protrudes between them. This segmentation creates physical separation that prevents bridging between adjacent word lines while still enabling selective electrical contact at different depths, thus improving both integration and reliability.
Solution Approach 2:
The insulating layers serve as intermediary structures that physically separate adjacent conductive layers and prevent bridging. The second region of the conductive layer protrudes through the insulating layers in a controlled manner, allowing electrical contact while the insulating material maintains isolation between non-contacting regions, thereby preventing short circuits.
3Reliability
If the thickness of conductive layers is increased to prevent bridging, then the structure stability is improved, but the height of the structure increases
Solution Approach 1:
The conductive layer exhibits local quality variation with the first region having standard thickness and the second region having increased thickness. This localized thickening occurs only where needed for bridging prevention and electrical contact, while other regions maintain their original dimensions, thus improving reliability without proportionally increasing the overall structure height.
Solution Approach 2:
Instead of uniformly increasing the thickness of the entire conductive layer, the invention utilizes the vertical dimension by having the second region protrude between upper and lower insulating layers. This selective vertical extension provides the necessary thickness for stability only where required, maintaining compact overall structure height.
Data Source
AI summary
A semiconductor device and a method of fabricating the same are provided. The semiconductor device includes insulating layers stacked in the shape of stairs, and conductive layers alternately stacked with the insulating layers, wherein the conductive layers each include a first region interposed between upper and lower insulating layers thereof, among the insulating layers, and a second region which extends from the first region and protrudes between the upper and lower insulating layers, and wherein a protruding part formed on a sidewall or an upper surface of the second region.