Helium-Enhanced Plasma Etching for DRAM Capacitor Openings
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Solution Overview
Problem
Conventional etching methods into silicon oxide-containing materials often result in bowing and twisting of openings, leading to capacitor shorting in DRAM arrays due to widened regions and inadequate selectivity between the silicon oxide material and masking layers.
Innovation Solution
A plasma etching process using a high concentration of helium, combined with fluorocarbons and carbon monoxide, is employed to form tapered openings with improved selectivity and reduced bowing, avoiding capacitor shorting by maintaining vertical sidewalls and optimizing etching conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used to form openings in silicon oxide-containing material, then the etching process can be completed, but bowing and twisting occur leading to widened regions and capacitor shorting
Solution Approach 1:
The patent changes the chemical parameters of the etching process by using a fluorocarbon-based plasma chemistry with specific gas flow ratios and pressure conditions. This parameter change transforms the etching behavior to produce vertical sidewalls and prevent bowing, directly resolving the contradiction between manufacturing precision and capacitor reliability
Solution Approach 2:
The patent employs a composite etching chemistry approach, combining fluorocarbon compounds with oxygen and other gases in specific proportions. This composite plasma environment creates a etching process that simultaneously achieves high precision opening formation and prevents harmful bowing effects, thereby ensuring capacitor isolation
2Manufacturing precision
If conventional etching chemistry is used, then the process is simpler, but selectivity between silicon oxide material and masking layers is inadequate
Solution Approach 1:
The patent achieves improved etching selectivity by changing the chemical composition parameters of the plasma etching process. The fluorocarbon-based chemistry with controlled oxygen content provides selective etching of silicon oxide while preserving the masking layers, thereby improving manufacturing precision without requiring additional process steps
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 new etching chemistry effectively prevents bowing and twisting, ensuring accurate formation of high aspect ratio openings and preventing adjacent capacitors from shorting, thereby enhancing the reliability of DRAM arrays.
Implementation Method 1
A plasma etching process using a high concentration of helium, combined with fluorocarbons and carbon monoxide, is employed to form tapered openings with improved selectivity and reduced bowing
Implementation Method 2
The new etching chemistry effectively prevents bowing and twisting, ensuring accurate formation of high aspect ratio openings
Data Source
AI summary
Methods of etching into silicon oxide-containing material with an etching ambient having at least 75 volume percent helium. The etching ambient may also include carbon monoxide, O2 and one or more fluorocarbons. The openings formed in the silicon oxide-containing material may be utilized for fabrication of container capacitors, and such capacitors may be incorporated into DRAM.