Plasma Processing Apparatus Electrode Segmentation
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Solution Overview
Problem
In plasma etching processes for semiconductor manufacturing, high-frequency power application leads to non-uniform plasma density and charge-up damages due to in-plane non-uniformity of plasma potential, causing CD non-uniformity and increased deposits, despite efforts to improve uniformity and control etching rates.
Innovation Solution
A plasma processing apparatus with a dual-frequency power system, where a first high-frequency power is applied to the lower electrode and a second low-frequency power is used for ion attraction, combined with independently controlled DC voltages on outer and inner electrodes to adjust frequency-impedance characteristics, ensuring impedance changes favor plasma density uniformity and suppress deposit adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high frequency power is applied to lower electrode for plasma generation, then plasma density becomes non-uniform due to skin effect and current concentration, leading to non-uniform processing and charge-up damages
Solution Approach 1:
The upper electrode is segmented into inner and outer regions with independent electrical control. This segmentation enables different plasma potential levels in different radial zones, counteracting the non-uniform plasma density distribution caused by high frequency current concentration at the central portion.
Solution Approach 2:
By applying appropriate DC voltages to the inner and outer electrodes, the system creates a more uniform plasma potential distribution across the processing area. This equipotential approach compensates for the non-uniform plasma density caused by skin effect and current concentration, improving processing 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
This approach enhances plasma density uniformity, increases the control range of plasma processing parameters, and reduces CD non-uniformity and deposit-related issues by optimizing plasma sheath formation and self-bias effects.
Implementation Method 1
electrons are accelerated by the high frequency electric field. Ionization by collision between the electrons and a processing gas generates a plasma
Implementation Method 2
a cathode coupling method in which a high frequency power is applied to a lower electrode which mounts thereon a substrate to be processed and serves as a cathode enables an anisotropic etching by attracting ions in the plasma to the substrate with a self-bias voltage generated in the lower electrode
Data Source
AI summary
A plasma processing apparatus includes a vacuum evacuable processing chamber, a first electrode divided into an outer electrode and an inner electrode, a second electrode, a first and a second high frequency power application unit for applying to the second electrode a first and a second high frequency power having a relatively high frequency and a relatively low frequency, respectively, a first and a second DC voltage application circuit apply a DC voltage to the outer and the inner electrode, respectively, and a processing gas supply unit. A space between the first electrode and the second electrode serves as a plasma generation space, and frequency-impedance characteristics of the outer electrode are set such that the impedance increases at the frequency of the second high frequency power and decreases at the frequency of the first high frequency power as the DC voltage applied to the outer electrode increases.