Nitrogen-Containing Cyclic Compounds for Plasma Etch Sidewall Passivation
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Solution Overview
Problem
High aspect ratio etching processes face challenges such as charge buildup on sidewalls, bowing, and twisting of etched features due to the insulating nature of traditional C:F polymers, which leads to incomplete etching and dimensional variations, especially in high aspect ratio structures like 3D NAND and DRAM applications.
Innovation Solution
The use of nitrogen-containing cyclic compounds as additives in plasma etching processes to form conductive sidewall passivation layers, which reduce charge buildup and improve the conductivity of the sidewall polymers, thereby enhancing the etching performance by forming a conductive polymer layer with a nitrogen content greater than 2.5%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional C:F polymer is used for sidewall passivation, then etching protection is provided, but charge buildup occurs leading to bowing and twisting of etched features
Solution Approach 1:
The patent changes the chemical composition parameters of the sidewall passivation layer by incorporating nitrogen-containing compounds (such as HCN, NH3, or nitrogen-containing organics) into the etching chemistry. This modifies the polymer composition from traditional C:F to a more conductive material with nitrogen content greater than 2.5%, thereby reducing charge buildup while maintaining etching protection
Solution Approach 2:
The patent creates a composite sidewall passivation layer that combines carbon, fluorine, and nitrogen elements. This composite material (C:F:N polymer) leverages the protective properties of traditional fluorocarbon polymers while incorporating nitrogen to provide electrical conductivity and reduce charge accumulation, resolving the contradiction between protection and dimensional control
2Use of energy by moving object
If bias power is increased to overcome charge buildup, then ion energy increases improving etching, but arcing and cooling challenges arise
Solution Approach 1:
The patent converts the harmful effect of charge buildup (which causes arcing and process instability) into a beneficial outcome by using nitrogen-containing compounds to create a conductive sidewall layer. This layer actively dissipates charge, transforming the charge buildup problem into an opportunity to improve process stability and reduce bias power requirements
3Manufacturing precision
If neutral flux compensation is increased for higher aspect ratios, then etching uniformity improves, but diffusion through HAR holes becomes more difficult
Solution Approach 1:
The patent changes the chemical reactivity parameters of the etching species by introducing nitrogen-containing compounds. This modifies the chemistry to produce more reactive species that can effectively etch through high aspect ratio structures without requiring excessive neutral flux compensation, thereby maintaining uniformity while simplifying the transport challenge
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 allows for the formation of substantially vertical structures with improved conductivity and reduced charge buildup, leading to better control of critical dimensions and reduced bias power requirements, while also facilitating easier cleaning and minimizing chamber contamination.
Implementation Method 1
The use of nitrogen-containing cyclic compounds as additives in plasma etching processes to form conductive sidewall passivation layers
Implementation Method 2
activating a plasma to produce an activated nitrogen-containing cyclic compound
Implementation Method 3
allowing an etching reaction to proceed between the film uncovered by the patterned mask layer and the activated nitrogen-containing cyclic compound
Implementation Method 4
Vertical isotropy of etched features is obtained by ion transport during plasma sheath formation
Data Source
AI summary
A method for forming a substantially vertical structure comprises: exposing a substrate to a vapor of an additive comprising a nitrogen-containing cyclic compound, the substrate having a film disposed thereon and a patterned mask layer disposed on the film, activating a plasma to produce an activated nitrogen-containing cyclic compound, and allowing an etching reaction to proceed between the film uncovered by the patterned mask layer and the activated nitrogen-containing cyclic compound to selectively etch the film from the patterned mask layer, thereby forming the substantially vertical structure, wherein the nitrogen-containing cyclic compound reduces a charge that builds up along sidewalls of the substantially vertical structure forming a conductive sidewall passivation layer on the sidewalls thereof. A method of depositing a conductive polymer layer on a substrate and a cyclic method are also disclosed.