3D Semiconductor Memory Stepped Insulating Layer Alignment
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Solution Overview
Problem
In semiconductor device manufacturing, misalignment between contact plugs and conductive patterns can lead to bridges between neighboring conductive patterns, causing operational errors due to the structural characteristics of three-dimensional semiconductor devices, where memory cells are stacked vertically.
Innovation Solution
A semiconductor device is designed with conductive patterns stacked in a stepped structure, a stepped insulating layer, and barrier patterns on the sidewalls, where contact plugs extend through the insulating layer to contact the conductive patterns, and the barrier patterns serve as etch stop layers to secure alignment margins, preventing misalignment and bridge formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact plugs are used to apply operating voltages to conductive patterns in three-dimensional semiconductor devices, then operational functionality is enabled, but misalignment between contact plugs and conductive patterns occurs causing bridges between neighboring conductive patterns
Solution Approach 1:
A stepped insulating layer is introduced as an intermediary structure between the contact plug and the conductive pattern. This stepped insulating layer includes multiple levels that correspond to different heights of stacked conductive patterns, providing a mediator that facilitates precise alignment and prevents direct contact between misaligned contact plugs and conductive patterns, thereby preventing bridge formation while maintaining electrical connectivity.
Solution Approach 2:
The insulating layer is segmented into a stepped structure with multiple levels rather than a single flat layer. Each step of the insulating layer corresponds to a specific height range where conductive patterns are located. This segmentation allows the insulating layer to provide alignment guidance at different vertical positions, ensuring that contact plugs align correctly with their corresponding conductive patterns while preventing bridges between neighboring patterns.
2Productivity
If conductive patterns are stacked vertically to improve integration density, then device functionality is enhanced, but bridges between conductive patterns easily occur due to misalignment
Solution Approach 1:
The stepped insulating layer serves as a mediator structure that accommodates the vertically stacked conductive patterns at different heights. By providing corresponding steps at each level, it ensures that contact plugs maintain proper alignment with their target conductive patterns throughout the vertical stack, preventing bridges between neighboring patterns while preserving the high integration density achieved through vertical stacking.
3Manufacturing precision
If barrier patterns are added on sidewalls of the stepped insulating layer, then alignment margins are secured preventing misalignment, but device structure becomes more complex
Solution Approach 1:
Barrier patterns are formed on the sidewalls of the stepped insulating layer during the manufacturing process before final contact plug formation. This preliminary action establishes physical boundaries and alignment references that guide subsequent processing steps, ensuring that contact plugs are deposited or formed at the correct positions with appropriate margins, thereby preventing misalignment and bridge formation while managing structural complexity through process integration.
Data Source
AI summary
A semiconductor device includes conductive patterns stacked and spaced apart from each other in a first direction to form a stepped structure, a stepped insulating layer overlapping the stepped structure, contact plugs extending through the stepped insulating layer in the first direction to contact respective contact portions of the conductive patterns, and barrier patterns disposed on sidewalls of the stepped insulating layer.