3D Memory Word Line Polysilicon Metal Composite Structure
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Solution Overview
Problem
3D memory devices with polysilicon word lines face issues such as increased carrier resistance and the possibility of a 'punching phenomenon' during contact formation, which affects device performance.
Innovation Solution
Incorporating a metal pattern surrounding a polysilicon inner pattern in the word lines, which reduces carrier resistance and prevents the punching phenomenon by enhancing contact reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polysilicon word lines are used in 3D memory devices, then the device structure is simple and manufacturing is easier, but carrier resistance increases and punching phenomenon occurs during contact formation
Solution Approach 1:
The word line is constructed as a composite structure with an inner pattern of polysilicon and an outer pattern of metal material surrounding it. This composite configuration combines the manufacturing simplicity of polysilicon with the low resistance and high contact reliability of metal, thereby reducing carrier resistance and preventing punching phenomenon during contact formation while maintaining ease of manufacture through sequential deposition processes.
2Ease of manufacture
If polysilicon word lines are used, then manufacturing process is simpler, but carrier resistance is higher
Solution Approach 1:
The word line employs a composite structure where the outer metal pattern provides low-resistance current paths, significantly reducing carrier resistance and energy loss. The inner polysilicon pattern maintains the beneficial properties of conventional processes, ensuring manufacturing simplicity is preserved while the metal component addresses the resistance issue.
3Loss of energy
If metal is added to word lines to reduce resistance, then carrier resistance decreases, but device structure becomes more complex
Solution Approach 1:
The word line is segmented into two distinct patterns: an inner pattern and an outer pattern. The inner pattern (polysilicon) maintains the original simple structure, while the outer pattern (metal) is added as a separate component. This segmentation allows the metal to be deposited and patterned independently, reducing the overall structural complexity compared to fully replacing the word line with metal, while still achieving low resistance.
Solution Approach 2:
The inner polysilicon pattern is nested within the outer metal pattern, creating a concentric structure. This nesting arrangement allows both materials to coexist in a compact configuration, minimizing the increase in device complexity while maximizing the beneficial effects of the low-resistance metal pathway.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The use of both polysilicon and metal in the word lines results in lower resistance and improved contact integrity, enhancing the overall performance of the 3D memory device.
Implementation Method 1
each of the plurality of word lines includes an inner pattern including polysilicon; and an outer pattern including metal, the outer pattern surrounds an outer surface of the inner pattern
Implementation Method 2
the contact plug is on the outer pattern
Data Source
AI summary
A 3D memory device and a method of manufacturing the same, the device including a substrate including a cell and an extension region; a cell stack including insulation layers and word lines alternately stacked on the substrate; channel structures vertically passing through the cell stack; a word line separation layer vertically passing through the cell stack and extending lengthwise in a first direction; a contact plug vertically connected to the word lines on the extension region; and a bit line extending lengthwise in a second direction on the channel structures, wherein each of the word lines includes an inner pattern including polysilicon; and an outer pattern including metal, the outer pattern surrounds an outer surface of the inner pattern, the channel structures vertically pass through the inner pattern, and the contact plug is on the outer pattern.