Variable Capacitor Current Distributor for Plasma Etching Uniformity
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Solution Overview
Problem
Conventional plasma etching processes using capacitively coupled plasma (CCP) and inductively coupled plasma (ICP) types face challenges in achieving uniform etching rates across the substrate, particularly between the center and edge regions due to plasma density imbalances.
Innovation Solution
An apparatus with a plasma generation unit comprising high-frequency power supply, first and second antennas, and a current distributor with variable capacitors to control current distribution and phase between the antennas, allowing for adjustment of the resonance point and current ratio to achieve uniform etching rates across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional current distributor is used in the plasma generation unit, then the etching process can be performed in all regions of the substrate, but the etching rate varies in the center region and edge region due to plasma density imbalance
Solution Approach 1:
The patent applies parameter changes by adjusting the capacitance values of capacitors in the current distributor to control the current ratio between inner and outer coils. By changing electrical parameters (capacitance) of existing components, the plasma density distribution is optimized to achieve uniform etching rates across the substrate without modifying the fundamental device structure.
2Productivity
If the plasma density is increased to improve etching rate, then the etching speed increases, but the plasma density becomes imbalanced between center and edge regions
Solution Approach 1:
The patent implements local quality by creating different current densities in different regions of the plasma chamber. Through the capacitor-based current distributor, the inner and outer coils receive different current ratios, resulting in localized plasma density optimization. This allows high etching rates in regions where plasma density is enhanced while maintaining uniformity across the entire substrate surface.
3Ease of operation
If a simple current distributor structure is used, then the device complexity is reduced, but the controllability of current ratio and phase between antennas is limited
Solution Approach 1:
The patent introduces capacitors as intermediary components between the power supply and the coils in the current distributor. These capacitors act as mediators that enable independent control of current ratio and phase difference between inner and outer coils. The capacitor-based intermediary structure provides precise controllability while maintaining a relatively simple overall device architecture.
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 enables uniform etching rates across all substrate regions by adjusting the resonance point and phase control, improving the controllability of the etching process and enhancing the etching rate uniformity, particularly in the edge regions.
Implementation Method 1
an inductively coupled plasma type... one or more coils are provided in the chamber and an RF signal is applied to the coils to induce an electromagnetic field in the chamber and generate the plasma
Implementation Method 2
the current distributor includes a first capacitor disposed between the first antenna and the second antenna; a second capacitor connected with the second antenna in series... the first capacitor and the second capacitor may be provided as variable capacitors
Data Source
AI summary
Disclosed is an apparatus for treating a substrate. The apparatus may include a chamber having a space for treating the substrate therein; a support unit supporting the substrate in the chamber; a gas supply unit supplying gas into the chamber; and a plasma generation unit exciting the gas in the chamber into a plasma state, wherein the plasma generation unit may include high frequency power supply; a first antenna; a second antenna; and a matcher connected between the high frequency power supply and the first and second antennas, wherein the matcher may include a current distributor distributing a current to the first antenna and the second antenna, and the current distributor includes a first capacitor disposed between the first antenna and the second antenna; a second capacitor connected with the second antenna in series; and a third capacitor connected with the second antenna in parallel, wherein the first capacitor and the second capacitor may be provided as variable capacitors.