Stepped Insulating Layer Etching for 3D NAND Selectivity
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Solution Overview
Problem
The existing methods for processing substrates with insulating layers in three-dimensional vertical NAND devices face challenges in achieving high etch selectivity and preventing short circuits between gates and metal films, particularly due to the formation of insulating layers on stepped structures.
Innovation Solution
A substrate processing method involving the formation of a first layer on a stepped structure, followed by weakening and densifying specific portions of it, and performing an isotropic etching process to separate the layers, which includes applying plasma to destroy bonding structures and using different plasma conditions for the first and second layers to achieve selective etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulating layer is deposited on a stepped structure to prevent short circuits, then the reliability of the device is improved, but the etch selectivity between different portions of the insulating layer deteriorates
Solution Approach 1:
The patent applies different plasma conditions to different spatial locations of the insulating layer. The upper and lower surfaces receive plasma treatment that densifies the insulating layer, while the side surfaces do not receive this treatment, maintaining the original structure. This creates local quality differences that enable selective etching of side surfaces while preserving upper and lower surfaces, thereby achieving both short circuit prevention and improved etch selectivity
Solution Approach 2:
The patent changes plasma parameters (power, gas flow rate, pressure) during the deposition process to control the density of the insulating layer at different locations. By adjusting these parameters, the upper and lower surfaces are densified while side surfaces remain less dense, creating etch rate differences that improve manufacturing precision without compromising reliability
2Manufacturing precision
If plasma is applied to densify the insulating layer, then the etch selectivity is improved, but the bonding structure of the insulating layer may be destroyed
Solution Approach 1:
The patent performs plasma treatment during the insulating layer formation process itself, before subsequent processing steps. This preliminary plasma application densifies the upper and lower surfaces while controlling the energy input to prevent bonding structure destruction. The process parameters are specifically optimized to achieve densification without compromising the mechanical integrity of the insulating layer
Solution Approach 2:
The patent uses periodic plasma pulsing with controlled duty cycles to alternately apply and pause plasma treatment. This periodic action allows the insulating layer to partially relax and re-bond between plasma pulses, preventing permanent bonding structure destruction while still achieving the desired densification effect for improved etch selectivity
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 method enhances etch selectivity and prevents short circuits by ensuring the first layer is removed more rapidly than the second layer during isotropic etching, allowing for the formation of conductive structures without compromising the integrity of the stepped structure.
Implementation Method 1
applying plasma to destroy bonding structures
Implementation Method 2
applying, onto the first layer, energy above a threshold inducing destruction of a bonding structure of at least a portion of the first layer
Implementation Method 3
energy below the threshold may be applied onto the second layer during the densifying of the second layer
Implementation Method 4
performing an isotropic etching process on the first layer and the second layer
Data Source
AI summary
Provided are a substrate processing method and a device manufactured by using the same, which may improve etch selectivity of an insulating layer deposited on a stepped structure. The substrate processing method includes: forming a first layer on a stepped structure having an upper surface, a lower surface, and a side surface connecting the upper surface and the lower surface; weakening at least a portion of the first layer; forming a second layer on the first layer; and performing an isotropic etching process on the first layer and the second layer.