RF Bias Filter for Plasma Etch Voltage Stability
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Solution Overview
Problem
Inconsistent voltage potential on electrodes during plasma etching processes leads to variations in etch depth and dimensions of semiconductor and MEMS devices, due to the combination of RF source energy and bias energy, causing instability and inefficiency in manufacturing.
Innovation Solution
A filter is introduced between the bias drive source and the electrode to block RF source energy and allow bias energy to pass through, with a designed impedance to minimize voltage fluctuations, ensuring consistent voltage control and uniform etch depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If RF source energy is applied to the electrode during plasma etching, then plasma is formed and etching process is enabled, but voltage potential on the electrode becomes inconsistent leading to variations in etch depth
Solution Approach 1:
The patent segments the electrical energy input by separating RF source energy and bias energy into distinct pathways. The RF energy is terminated through a dedicated RF ground path, while bias energy is applied separately through a filter to the electrode, allowing independent control of each energy type to prevent their interfering combination.
Solution Approach 2:
The patent introduces a filter as an intermediary component between the bias drive source and the electrode. This filter selectively blocks RF source energy from reaching the bias drive source while allowing bias energy to pass through, thereby mediating the interaction between the two energy types and preventing voltage fluctuations.
2Manufacturing precision
If bias energy is applied to control ion directionality, then etch anisotropy and dimension control are improved, but RF source energy interference causes voltage fluctuations and reduces control stability
Solution Approach 1:
The filter serves as an intermediary that protects the bias drive source from RF interference. It allows the bias energy to effectively control ion directionality while blocking RF source energy from causing voltage fluctuations, thereby ensuring stable and reliable voltage control for precise etch dimension control.
Solution Approach 2:
The patent extracts the harmful RF source energy from the bias energy pathway using the filter. By removing the RF interference component while retaining the useful bias energy, the system achieves stable voltage control necessary for precise etch dimension control without the destabilizing effect of RF interference.
3Adaptability or versatility
If RF source energy and bias energy are combined at the electrode, then plasma etching functionality is achieved, but the combination causes instability in voltage potential and etch depth variations
Solution Approach 1:
The patent segments the energy combination by creating separate termination paths for RF and bias energies. RF energy is terminated through a dedicated ground path with RF choke and capacitor, while bias energy is applied separately through a filter, maintaining the functional combination needed for plasma etching while ensuring voltage potential consistency through independent control.
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 filter system significantly reduces variations in etch depth, improving the consistency and uniformity of etched features, enhancing the precision and efficiency of semiconductor and MEMS device manufacturing.
Implementation Method 1
A filter may be disposed between the bias drive source and the electrode, and configured to pass bias energy to the electrode and block RF source energy from reaching the bias drive source
Implementation Method 2
The RF source energy may be configured to be terminated to ground through an electrode disposed within the processing chamber
Implementation Method 3
A bias drive source may apply a bias to the electrode to control the directionality of the ions from the plasma such that it allows control of dimensions and anisotropy of etched features
Implementation Method 4
designed to deliver RF source energy so that it that forms a plasma within a processing chamber
Data Source
AI summary
A plasma-assisted etch process for the manufacture of semiconductor or MEMS devices employs an RF source to generate a plasma that is terminated through an electrode. The termination is designed as a “short” at the frequency of the RF source to minimize voltage fluctuations on the electrode due to the RF source energy. The electrode voltage potential can then be accurately controlled with a bias source, resulting in improved control of etch depth of a semiconductor substrate disposed on the electrode.