Nonvolatile Memory Contact Plug Reliability via Segmented Formation
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Solution Overview
Problem
The integration density of nonvolatile memory devices is limited by the area occupied by unit memory cells, and the process of forming contact plugs in three-dimensional memory devices is prone to reliability issues.
Innovation Solution
A nonvolatile memory device with a substrate having a common source line, stacked word lines, and contact plugs that penetrate insulating patterns and layers, connected to bonding metals and circuit elements, enhancing the reliability of the contact plug formation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If three-dimensional memory device structure is adopted to increase integration density, then integration density is improved, but reliability of contact plug formation deteriorates
Solution Approach 1:
The contact plug formation process is segmented into multiple sequential steps: forming a contact hole through the insulating layer, depositing a first metal layer in the contact hole, forming a second insulating layer over the first metal layer, and depositing a second metal layer. This segmentation allows each step to be optimized independently, improving overall reliability while maintaining the three-dimensional structure for high integration density.
Solution Approach 2:
The method performs preliminary actions by first forming the contact hole and first metal layer before subsequent processing steps. The first metal layer is deposited and prepared in advance, and the second insulating layer is formed over it beforehand, ensuring proper preparation and alignment before final contact plug completion, which enhances formation reliability.
2Reliability
If contact plugs penetrate through insulating patterns and layers to connect circuit elements, then electrical connection is improved, but process complexity increases
Solution Approach 1:
The contact plug structure employs nesting by placing the first metal layer inside the contact hole, then covering it with the second insulating layer, and finally depositing the second metal layer on top. This nested arrangement ensures stable electrical connections while organizing the complex multi-layer structure in a systematic manner that simplifies process control.
Data Source
AI summary
The nonvolatile memory device includes a substrate including a first surface and a second surface opposite to the first surface in a first direction; a common source line on the first surface of the substrate; a plurality of word lines stacked on the common source line; a first insulating pattern spaced apart from the plurality of word lines in a second direction crossing the first direction, and in the substrate; an insulating layer on the second surface of the substrate; a first contact plug penetrating the first insulating pattern and extending in the first direction; a second contact plug penetrating the insulating layer, extending in the first direction, and connected to the first contact plug; an upper bonding metal connected to the first contact plug and connected to a circuit element; and a first input/output pad connected to the second contact plug and electrically connected to the circuit element.