ICP Etching Bias Frequency for High-Aspect-Ratio Insulator Patterns
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Solution Overview
Problem
Current inductively coupled plasma etching technologies face challenges in achieving high ion energy for high aspect ratio pattern etching, particularly in insulating materials, and struggle with controlling ion energy and environmental impact due to high global warming potential gases.
Innovation Solution
An inductively coupled plasma etching apparatus with a reaction chamber, upper and lower electrodes, and a gas supply system that uses a liquid source with low ion density, where the lower electrode operates at a lower frequency than the upper coil, allowing for controlled ion energy and eco-friendly gas sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional inductively coupled plasma etching is used, then high ion density is achieved, but sufficient ions cannot reach the bottom surface of high aspect ratio patterns
Solution Approach 1:
The patent changes the frequency parameter of the lower electrode from conventional RF frequencies to low frequency (1-100 kHz), which fundamentally alters ion transport characteristics. This frequency change enables ions to be effectively accelerated toward the substrate while maintaining high ion density in the plasma, allowing sufficient ions to reach the bottom surface of high aspect ratio patterns with uniform etching.
2Use of energy by moving object
If capacitively coupled plasma etching is used to etch high aspect ratio patterns, then ion energy is high, but the gas ionization rate is low and ion energy control is difficult
Solution Approach 1:
The patent segments the plasma generation and ion acceleration functions into two independent components: the upper coil generates high-density plasma through inductive coupling, while the lower electrode independently controls ion energy through low frequency power. This segmentation allows high ionization rate from the coil while maintaining precise ion energy control via the lower electrode frequency and power, overcoming the limitations of capacitively coupled plasma.
3Productivity
If very large bias power is used in capacitively coupled plasma to etch HARC patterns, then etching capability is sufficient, but arcing phenomenon occurs in the chamber
Solution Approach 1:
The patent changes the frequency parameter of the lower electrode to low frequency (1-100 kHz), which fundamentally alters the power delivery characteristics. This frequency change enables sufficient ion acceleration for HARC etching while distributing the power delivery in a manner that prevents arcing, thereby maintaining both etching capability and chamber stability.
4Manufacturing precision
If conventional PFC-based etching gas is used, then etching performance is good, but global warming potential is high
Solution Approach 1:
The patent changes the physical state of the etching gas from conventional gaseous PFC to liquid source material. This state change enables the use of alternative materials with lower global warming potential while maintaining effective etching performance through the enhanced ion density and controlled ion energy provided by the low frequency biased electrode.
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 apparatus effectively etches high aspect ratio patterns with uniform critical dimensions and minimizes damage to insulating films, while reducing global warming potential by using low ion density liquid sources, enabling efficient and environmentally friendly semiconductor processing.
Implementation Method 1
an upper coil part configured to induce an electric field into the inner space of the reaction chamber and form an inductively coupled plasma from the gas source by the electric field
Implementation Method 2
a lower electrode part provided on a lower side of the mounting part to induce at least any one of ions and neutral active species forming the inductively coupled plasma and involved in etching toward the object to be etched
Data Source
AI summary
Provided is an inductively coupled plasma etching apparatus comprising: a reaction chamber having an inner space to which a gas source is provided; an upper coil part for inducing an electric field into the inner space of the reaction chamber and configured to form an inductively coupled plasma from the gas source by the electric field; a mounting part which faces the upper coil part and on which an object to be etched by the inductively coupled plasma is disposed; and a lower electrode part provided on the lower side of the mounting part to induce at least any one of ions and neutral active species constituting the inductively coupled plasma and involved in etching toward the object to be etched disposed on the mounting part, wherein the frequency of the lower electrode part is lower than the frequency of the upper coil part. In addition, provided is a method in which power of a lower frequency than the frequency applied to an upper electrode is applied to a lower electrode so that an object to be etched, which has been patterned with a mask material, is etched vertically using an inductively coupled plasma apparatus.