HF Plasma Etching of Silicon Films for 30 Nm Pattern Precision
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Solution Overview
Problem
Existing plasma etching methods struggle to efficiently form precise concave portions in silicon-containing films with narrow opening patterns, often resulting in defects and roughness due to high energy bias signals and inadequate control of plasma conditions.
Innovation Solution
A plasma processing method using a bias signal with an effective power of less than 2 kW or negatively-polarized DC pulses below 2 kV, combined with controlled temperature settings and specific gas compositions, including hydrogen fluoride, to etch silicon-containing films through a mask film with a 30 nm or less opening pattern, ensuring precise concave portion formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high energy bias signals are used for plasma etching, then etching speed is improved, but pattern precision and surface quality deteriorate due to defects and roughness
Solution Approach 1:
The patent applies parameter changes by precisely controlling the bias signal power (effective value of 2 kW or less) and adjusting plasma processing conditions (gas composition, pressure, temperature) to achieve optimal etching results that balance speed and precision for narrow opening patterns
Solution Approach 2:
The patent employs dynamic control of processing parameters during plasma etching, including time-dependent adjustment of bias power and gas flow rates, to maintain pattern precision while achieving adequate etching speed throughout the process
2Productivity
If high energy bias signals are used for plasma etching, then etching speed is improved, but surface quality deteriorates due to plasma-induced roughness
Solution Approach 1:
The patent reduces plasma-induced roughness by changing the energy parameter of the bias signal to an effective value of 2 kW or less, and by optimizing gas composition and pressure conditions to achieve smooth surface etching while maintaining adequate processing speed
3Ease of operation
If conventional plasma conditions are used for narrow opening patterns, then processing simplicity is maintained, but pattern fidelity deteriorates due to defects
Solution Approach 1:
The patent modifies plasma processing parameters including bias power (effective value of 2 kW or less), gas composition (specific ratios of fluorocarbon and oxygen), and pressure conditions to enable faithful reproduction of narrow opening patterns (30 nm or less) while maintaining operational simplicity
Solution Approach 2:
The patent implements feedback control by monitoring etching progress and adjusting processing parameters in real-time to prevent defects and ensure accurate pattern formation in narrow opening structures
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 precise and defect-reduced concave portions in silicon-containing films, improving the uniformity and quality of etched patterns while minimizing plasma-induced roughness and defects.
Implementation Method 1
forming plasma from the processing gas in the chamber
Implementation Method 2
etching the silicon-containing film through the mask film to form a concave portion
Data Source
AI summary
A plasma processing method executed in a plasma processing apparatus, including a chamber and a substrate support provided in the chamber, the method including (a) preparing a substrate including a silicon-containing film and a mask film on the silicon-containing film, which is an inorganic film containing silicon, and the mask film including an opening pattern; and (b) forming plasma in the chamber and etching the silicon-containing film through the mask film to form a concave portion in the silicon-containing film, the (b) including (b-1) supplying a processing gas containing hydrogen fluoride into the chamber, (b-2) forming plasma from the processing gas in the chamber, and (b-3) supplying a bias signal to the substrate support, the bias signal being a bias RF signal or a bias DC signal including a sequence of negatively-polarized DC pulses.