Vertical Memory Common Source Contact Venting Against Voids
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Solution Overview
Problem
In the manufacturing of vertical memory devices, voids in the common source line contact plug can lead to electrical shorts and swelling due to confined by-product gases, compromising the reliability of the device.
Innovation Solution
A method involving the formation of a mold structure, an opening for the common source line, and contact plugs with an open passage to exhaust gases, followed by the creation of buried and barrier films to ensure electrical insulation and proper contact formation, thereby preventing gas confinement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a common source line contact plug is formed in an opening using conventional methods, then the contact plug can be manufactured, but voids form in the interior of the contact plug due to confined by-product gases, leading to electrical shorts and swelling
Solution Approach 1:
A vent hole is formed in the contact plug structure before the contact plug material is fully deposited. This preliminary action creates a gas escape path that prevents void formation during subsequent manufacturing steps, thereby eliminating the root cause of electrical shorts and swelling while maintaining ease of manufacture
Solution Approach 2:
The vent hole acts as an intermediary structure that facilitates the escape of by-product gases during contact plug formation. This intermediate feature resolves the contradiction by providing a controlled pathway for gas removal, preventing harmful void formation without complicating the overall manufacturing process
2Ease of manufacture
If a common source line contact plug is formed in an opening using conventional methods, then the contact plug can be manufactured, but the top surface of the contact plug swells in a direction perpendicular to the top surface of the substrate due to confined gas
Solution Approach 1:
The vent hole is created in advance before contact plug material deposition is complete. This preliminary structuring allows gas to escape during the forming process, preventing pressure buildup that would cause surface swelling and maintaining manufacturing precision
Solution Approach 2:
The introduction of the vent hole changes the physical parameters of the contact plug structure by creating an internal void space that can accommodate gas expansion. This parameter change allows the contact plug to form without gas-induced swelling, maintaining surface flatness while preserving ease of manufacture
3Reliability
If a separation film pattern is used to electrically insulate gate lines from the common source line contact plug, then electrical insulation is provided, but the separation film pattern may be melted away due to gas, causing electrical shorts
Solution Approach 1:
The harmful by-product gas is extracted from the system through the vent hole in the contact plug. By removing the gas source before it can reach and degrade the separation film pattern, the electrical insulation function is preserved without the harmful effects of gas-induced melting
Solution Approach 2:
The vent hole serves as an intermediary escape route for by-product gases, directing them away from the separation film pattern. This intermediate gas pathway protects the insulating film from thermal degradation while maintaining the electrical insulation function
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
This approach enhances the reliability of vertical memory devices by preventing electrical shorts and swelling, ensuring stable contact formation and improved manufacturing processes.
Implementation Method 1
the first contact plug includes an open passage of the recessed region in the vicinity of an entrance of the opening for the common source line, and after forming the first contact plug, exhausting a gas in the recessed region outside the recessed region through the open passage
Data Source
AI summary
Vertical memory devices, and methods of manufacturing the same, include providing a substrate including a cell array region and a peripheral circuit region, forming a mold structure in the cell array region, forming an opening for a common source line passing through the mold structure and extending in a first direction perpendicular to a top surface of the substrate, forming a first contact plug having an inner sidewall delimiting a recessed region in the opening for the common source line, and forming a common source bit line contact electrically connected to the inner sidewall of the first contact plug.