Metal-Containing Trench Liners to Prevent 3D NAND Collapse
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Solution Overview
Problem
During the fabrication of vertically-stacked memory devices, such as three-dimensional NAND, unintended etching of supporting semiconductor material can lead to structural collapse due to galvanic corrosion caused by exposure of metal-containing conductive material, resulting in device failure.
Innovation Solution
The implementation of metal-containing liners at the bottoms of trenches or openings to prevent galvanic corrosion by forming a conductive liner between the NAND channel material and the NAND source structure, improving conductivity and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal-containing conductive material is exposed during fabrication, then conductivity is improved, but galvanic corrosion occurs causing structural collapse
Solution Approach 1:
A liner material is introduced as an intermediary layer between the metal-containing conductive material and the etchant environment. This liner acts as a protective mediator that prevents direct contact between the metal and corrosive chemicals, thereby eliminating galvanic corrosion while maintaining the underlying conductive structure's functionality.
Solution Approach 2:
The liner is formed in advance before subsequent etching and fabrication steps. This preliminary protective layer prevents galvanic corrosion from occurring in the first place by creating a barrier that stops the harmful electrochemical reaction between exposed metal and the etchant solution.
2Reliability
If trenches are formed to expose metal-containing material, then conductivity between NAND channel and source structure is improved, but supporting semiconductor material undergoes unintended etching
Solution Approach 1:
The liner serves as a protective intermediary that allows trenches to be formed for electrical connection while preventing the supporting semiconductor material from undergoing unintended etching. The liner is selectively positioned to protect vulnerable areas during the trench formation process.
Solution Approach 2:
The liner is applied locally at specific positions where metal-containing material is exposed, rather than uniformly across the entire structure. This localized protection allows trenches to be formed where needed for conductivity while preventing etching damage only in the critical areas where metal exposure occurs.
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 solution effectively prevents the collapse of vertically-stacked structures by preventing galvanic corrosion, ensuring reliable device performance and preventing device failure.
Implementation Method 1
unintended etching of supporting semiconductor material can lead to structural collapse due to galvanic corrosion caused by exposure of metal-containing conductive material
Data Source
AI summary
Some embodiments include methods of forming integrated assemblies. A conductive structure is formed to include a semiconductor-containing material over a metal-containing material. An opening is formed to extend into the conductive structure. A conductive material is formed along a bottom of the opening. A stack of alternating first and second materials is formed over the conductive structure either before or after forming the conductive material. Insulative material and/or channel material is formed to extend through the stack to contact the conductive material. Some embodiments include integrated assemblies.