Carbon Encapsulation Layer for 3D NAND Staircase Etch Selectivity
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Solution Overview
Problem
Conventional techniques for forming 3D NAND structures face challenges in scaling to smaller devices and cause degradation at oxide-oxide interfaces and punchthrough of tungsten wordlines during etching, leading to inefficiencies and reduced throughput in fabrication processes.
Innovation Solution
A carbon-containing encapsulation layer is deposited over the staircase pattern in 3D NAND structures to act as an etch selectivity layer and prevent degradation, using techniques like atomic layer deposition or chemical vapor deposition to ensure conformal coverage and high selectivity during nitride etching and via formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional techniques are used for forming 3D NAND structures, then fabrication can proceed with standard processes, but degradation occurs at oxide-oxide interfaces and tungsten wordlines punchthrough during etching
Solution Approach 1:
A carbon-containing encapsulation layer is deposited between the oxide layers and nitride layers to act as a protective intermediary. This encapsulation layer prevents direct etching damage to the oxide-oxide interfaces and stops tungsten wordline punchthrough during subsequent etching processes, thereby improving interface integrity without disrupting the standard fabrication flow
Solution Approach 2:
The carbon-containing encapsulation layer is deposited in advance before the etching of nitride layers and formation of vias. This preliminary protective action ensures that the oxide interfaces are shielded from harmful etching effects before they can occur, preventing degradation rather than correcting it afterward
2Reliability
If a carbon-containing encapsulation layer is deposited to prevent degradation and improve etch selectivity, then interface integrity and fabrication reliability improve, but process complexity and deposition time increase
Solution Approach 1:
The encapsulation layer uses carbon-containing materials deposited via ALD or CVD processes that offer high etch selectivity (2:1 to 100:1) compared to conventional materials. By changing the material composition to carbon-based compounds, the process achieves superior protective functionality with controlled deposition parameters, improving fabrication reliability while managing process complexity through parameter optimization
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 carbon-containing encapsulation layer effectively prevents degradation at oxide-oxide interfaces and reduces punchthrough of tungsten wordlines, enhancing the efficiency and reliability of the 3D NAND structure fabrication process by improving etch selectivity and reducing unwanted connections.
Implementation Method 1
depositing a carbon-containing encapsulation layer to encapsulate both the first oxide and nitride layers
Implementation Method 2
depositing a carbon-containing encapsulation layer to encapsulate both the first oxide and nitride layers
Implementation Method 3
generating one or more radicals of the source gas in the plasma source from the source gas
Implementation Method 4
one or more radicals of the source gas are in a substantially low energy state that react with the silicon-containing and carbon-containing precursor to form the carbon-containing encapsulation film
Data Source
AI summary
Methods and apparatuses for depositing an encapsulation layer over a staircase structure during fabrication of a 3D NAND structure to prevent degradation of an oxide-oxide interface and to prevent punchthrough of a wordline are provided. The encapsulation layer is a carbon-containing conformal film deposited over a staircase structure of alternating oxide and nitride layers prior to depositing oxide over the staircase structure.