Air Gap Silicide Formation for 3D Memory Structural Integrity
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Solution Overview
Problem
The challenge in manufacturing semiconductor devices with three-dimensional memory structures is the volume expansion during thermal reaction of metal silicide formation, which can lead to tilt or collapse of stacked portions, necessitating a process that accounts for this expansion to maintain structural integrity and facilitate processing.
Innovation Solution
A method involving the formation of air gaps between metal silicide layers, where a silicon film is partially absent, allowing controlled thermal reaction with a metal film to form nickel silicide layers without complete filling of air gaps, thereby managing volume expansion and preventing structural issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal reaction is performed to form metal silicide layers, then the electrode layers are formed with good electrical conductivity, but volume expansion occurs causing tilt or collapse of stacked portions
Solution Approach 1:
Air gaps are intentionally formed between stacked metal silicide layers before thermal reaction to provide expansion space. This cushioning structure prevents volume expansion from causing tilt or collapse during the silicidation process, while still allowing the formation of electrically conductive metal silicide layers.
Solution Approach 2:
The physical state of the gap between metal silicide layers is changed from solid (no gap) to gaseous (air gap), creating expansion space that accommodates volume increase during thermal reaction. This parameter change allows the stacked structure to maintain integrity while forming conductive metal silicide layers.
2Stability of the object's composition
If air gaps are completely filled with silicon film, then continuous metal silicide layers are formed, but volume expansion causes tilt or collapse
Solution Approach 1:
The silicon film is selectively formed in specific regions (on insulating films and in partial air gaps) while leaving other regions (communication portions of air gaps) intentionally empty. This local quality differentiation allows continuous metal silicide formation where needed while maintaining structural stability where expansion occurs.
Solution Approach 2:
The air gaps are partially filled with silicon film rather than completely filled. This partial action provides enough silicon for metal silicide formation while leaving sufficient empty space to accommodate volume expansion and prevent structural collapse.
3Stability of the object's composition
If metal film is formed on all surfaces including slit sides, then complete metal silicide layers are formed, but processing complexity increases
Solution Approach 1:
The metal film formation process is extracted from being a complete all-surface deposition to a selective deposition only on specific surfaces (insulating film surfaces and air gap surfaces excluding slit communication portions). This extraction simplifies processing by eliminating the need to form and subsequently remove metal film from slit sides.
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 prevents tilt and collapse of stacked portions, allows for the formation of nickel silicide layers without voids, and reduces interconnect capacitance, enabling efficient and reliable operation of memory cells.
Implementation Method 1
causing reaction between the metal film and the silicon film to form a plurality of metal silicide layers
Implementation Method 2
forming metal silicide involves volume expansion
Implementation Method 3
Thermal reaction for forming metal silicide involves volume expansion
Data Source
AI summary
According to one embodiment, a method for manufacturing a semiconductor device includes forming a silicon film on an upper surface side, a lower surface side, and a side surface side of an air gap, while leaving part of the air gap between the silicon film formed on the upper surface side and the silicon film formed on the lower surface side. The method includes forming a metal film on a side surface of the slit. The method includes forming a plurality of metal silicide layers between the second layers by causing reaction between the metal film and the silicon film. The method includes removing unreacted part of the metal film formed on the side surface of the slit.