Dual RF and DC Plasma Processing for Etch Selectivity
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Solution Overview
Problem
Current plasma etching technologies face challenges in achieving high selectivity and uniformity, particularly with ArF photo-resist films, which have poor plasma resistance, leading to surface roughness and etching issues, and struggle with deposition on electrodes affecting process consistency.
Innovation Solution
A plasma processing apparatus with a dual RF power system applying different frequencies to the lower electrode and a DC power supply to the upper electrode, allowing for variable voltage and current control, which enhances plasma density, reduces deposition, and improves etching selectivity and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the power level of RF power for plasma generation applied to the upper electrode is increased, then the plasma density increases, but the electrode may be etched, bringing about process characteristics different from those obtained by a lower power level
Solution Approach 1:
The patent changes the power supply method from RF to DC for the upper electrode, and applies different frequencies (27 MHz or higher) for the lower electrode, to achieve plasma generation without electrode damage while maintaining plasma density
Solution Approach 2:
The patent divides the power supply into two independent systems: DC power supply for the upper electrode and dual-frequency RF power supply for the lower electrode, allowing independent optimization of each electrode's function
2Manufacturing precision
If the thickness of photo-resist films is reduced to achieve smaller pattern opening portions, then micro-fabrication precision increases, but the plasma resistance properties deteriorate, causing surface roughness and etching selectivity problems
Solution Approach 1:
The patent changes the power supply parameters (DC for upper electrode, dual-frequency RF for lower electrode) to create a plasma environment that is less damaging to thin photo-resist films, maintaining their structural integrity while enabling precise patterning
Solution Approach 2:
The patent uses dual-frequency RF power supply to dynamically control the plasma characteristics, allowing optimization of plasma density and ion energy to protect thin resist films during etching
3Productivity
If the pressure in the chamber is increased, then the etching rate increases, but the plasma density becomes low at the chamber central portion, making it difficult to control the plasma density
Solution Approach 1:
The patent uses dual-frequency RF power supply to dynamically adjust plasma characteristics, enabling maintenance of uniform plasma density across the chamber even at elevated pressures where conventional single-frequency systems fail
Solution Approach 2:
The patent changes the frequency parameters of RF power supply (using 27 MHz or higher frequencies) to improve plasma confinement and density uniformity in the chamber center at high pressure conditions
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 solution achieves high selectivity and uniform etching, maintains plasma resistance of the resist layer, reduces electrode deposition, and increases etching rate and plasma density uniformity, even at high chamber pressures.
Implementation Method 1
an RF for plasma generation is applied to the upper electrode to generate plasma
Implementation Method 2
an RF (radio frequency) is applied to one of the electrodes to form an electric field between the electrodes. The process gas is turned into plasma by the RF electric field
Implementation Method 3
a DC power supply to the upper electrode, allowing for variable voltage and current control, which enhances plasma density
Implementation Method 4
plasma etching processes, which utilize plasma to etch a layer through a resist mask
Implementation Method 5
The process gas is turned into plasma by the RF electric field, thereby performing plasma etching on a predetermined layer disposed on a semiconductor wafer
Implementation Method 6
A plasma processing apparatus with a dual RF power system applying different frequencies to the lower electrode
Implementation Method 7
an RF (radio frequency) is applied to one of the electrodes to form an electric field between the electrodes
Data Source
AI summary
An apparatus includes an upper electrode and a lower electrode for supporting a wafer disposed opposite each other within a process chamber. A first RF power supply configured to apply a first RF power having a relatively higher frequency, and a second RF power supply configured to apply a second RF power having a relatively lower frequency is connected to the lower electrode. A variable DC power supply is connected to the upper electrode. A process gas is supplied into the process chamber to generate plasma of the process gas so as to perform plasma etching.