Low-Temperature HAR Etching for Vertical Dielectric Openings
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Solution Overview
Problem
Conventional methods for forming high aspect ratio openings in semiconductor devices result in non-uniform sidewalls due to bowing, compromising the structural and electronic integrity of 3D memory devices, as polymers formed at higher temperatures fail to conformally cover the entire depth of the openings, leading to inadequate protection and increased etching.
Innovation Solution
A method of forming high aspect ratio openings at a temperature of less than about 0°C, using an etch composition with etch gas, additive gas, and protective material precursor to create a conformal protective material on the sidewalls, which is resistant to subsequent process conditions and selectively formed to prevent lateral etching, ensuring uniformity and verticality of the sidewalls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polymers are formed at higher temperatures (20°C or greater) to protect sidewalls from overetching, then the polymer formation rate increases, but the polymers fail to conformally cover the entire depth of high aspect ratio openings, leading to inadequate protection and increased bowing
Solution Approach 1:
The patent changes the temperature parameter from conventional high temperatures (20°C or greater) to low temperature (less than 0°C, specifically -50°C to -100°C). This parameter change enables both sufficient polymer formation rate and complete conformal coverage throughout the entire depth of high aspect ratio openings, as the low temperature conditions allow reactants to penetrate and react uniformly along the full depth of the openings while maintaining adequate polymer deposition rates
Solution Approach 2:
The patent employs periodic action by conducting the etching and polymer formation processes in alternating cycles. The etch composition is introduced periodically to etch the dielectric material, followed by periodic introduction of reactants to form protective polymer material. This periodic alternation allows the process to achieve both vertical sidewall formation and complete conformal polymer coverage throughout the opening depth
2Productivity
If conventional anisotropic etch techniques are used to form high aspect ratio openings, then the etching process can be performed, but the dielectric material is not uniformly etched in vertical and horizontal directions, resulting in bowed sidewalls with non-uniform width
Solution Approach 1:
The patent applies preliminary anti-action by forming protective polymer material on the sidewalls before the etching process completes. The polymer material is deposited conformally on the sidewalls during the etching process, creating a protective layer that prevents lateral etching and overetching. This preliminary protection counteracts the tendency toward bowing and non-uniform sidewall formation that occurs with conventional anisotropic etching
Solution Approach 2:
The patent uses composite materials by combining the etch composition (containing etch gases like SF6, CF4, or CHF3) with protective material precursors (such as oxygen-containing compounds like O2, CO, or CO2). This composite etch composition simultaneously performs etching and forms protective polymer material on the sidewalls, achieving both vertical etching efficiency and sidewall uniformity
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 method achieves substantially vertical and uniformly dimensioned high aspect ratio openings with reduced bowing, enhancing the structural and electronic integrity of semiconductor devices by effectively protecting the sidewalls from overetching and maintaining dimensional uniformity.
Implementation Method 1
the dielectric material is not uniformly etched in the vertical and horizontal directions by conventional anisotropic etch techniques
Implementation Method 2
A protective material is formed in the HAR openings at a temperature of less than about 0° C.
Data Source
AI summary
Methods of forming high aspect ratio openings. The method comprises removing a portion of a dielectric material at a temperature less than about 0° C. to form at least one opening in the dielectric material. The at least one opening comprises an aspect ratio of greater than about 30:1. A protective material is formed in the at least one opening and on sidewalls of the dielectric material at a temperature less than about 0° C. Methods of forming high aspect ratio features are also disclosed, as are semiconductor devices.