Plasma Control System for Thin-Film Etching Anisotropy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current RF-excited gaseous discharge systems in thin film fabrication face challenges in controlling Ion Energy Distribution Function (IEDF) and ion bombardment, affecting the anisotropy of thin-film etching and surface damage, due to limitations in precise timing and control of RF and bias bursts.
Innovation Solution
A plasma system comprising a plasma chamber, an RF plasma generator, a bias generator, and a controller that produces controlled RF bursts and bias bursts with precise timing, allowing for the creation and acceleration of ions within the plasma chamber, with the controller adjusting parameters such as burst turn on/off times and pulse frequencies to optimize plasma properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If RF and bias bursts are applied continuously without precise timing control, then plasma generation is maintained, but ion energy distribution control is poor leading to reduced etching anisotropy and increased surface damage
Solution Approach 1:
The patent applies periodic pulsed RF and bias bursts instead of continuous application. The RF generator delivers RF power in bursts synchronized with bias bursts, creating periodic plasma generation and ion acceleration cycles. This periodic action enables precise control over ion energy distribution by adjusting burst duration, frequency, and timing, thereby improving etching anisotropy while maintaining plasma generation.
Solution Approach 2:
The patent implements preliminary action by applying RF bursts before bias bursts to pre-ionize the plasma. The RF power is applied in advance to create sufficient plasma density before the bias voltage accelerates ions, ensuring that when ions are accelerated, adequate plasma is available for controlled etching. This preliminary plasma generation improves ion energy control and etching anisotropy.
2Quantity of substance
If RF burst duration is extended to maintain plasma density, then plasma generation is improved, but ion energy distribution control is reduced affecting etching precision
Solution Approach 1:
The patent uses periodic pulsed RF bursts with optimized duration to maintain plasma density. By delivering RF power in repeated short bursts rather than continuous application, the system sustains plasma through periodic regeneration while allowing the plasma to decay partially between bursts. This periodic action enables control over average plasma density while maintaining precise ion energy distribution during the actual etching phases.
Solution Approach 2:
The patent implements dynamic control of RF burst parameters including duration, frequency, and amplitude. The RF burst characteristics are adjusted in real-time based on process requirements, allowing optimization of plasma density during different phases of the etching cycle. This dynamic adjustment enables maintaining adequate plasma density while preserving precise ion energy control during ion acceleration phases.
3Productivity
If bias voltage is increased to improve ion acceleration, then ion bombardment energy increases improving etching rate, but surface damage increases
Solution Approach 1:
The patent applies periodic bias bursts with controlled duration and frequency to accelerate ions. By delivering bias voltage in pulsed form rather than continuous DC, the system achieves high peak ion bombardment energy during short intervals to maintain etching rate, while allowing the plasma and surface to relax between pulses, reducing cumulative surface damage. The periodic nature enables separation of high-energy ion impact moments from lower-energy periods.
Solution Approach 2:
The patent changes the temporal parameters of bias application from continuous to pulsed, and further to synchronized periodic bursts. By adjusting bias pulse width, frequency, and amplitude independently, the system optimizes ion bombardment energy to achieve high etching rates while controlling surface damage. The parameter changes enable decoupling of peak ion energy (for etching rate) from average ion energy (affecting surface damage).
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 system enables more precise control over plasma etching processes, improving the anisotropy of thin-film etching and reducing surface damage by finely tuning the ion energy distribution, leading to faster and more controlled plasma etching with better mask erosion resistance and deeper, straighter holes/trenches.
Implementation Method 1
RF-excited gaseous discharges in thin film fabrication technology has become standard
Implementation Method 2
The RF plasma generator may be electrically coupled with the plasma chamber and may produce a plurality of RF bursts, each of the plurality of RF bursts including RF waveforms
Implementation Method 3
The bias generator may be electrically coupled with the plasma chamber and may produce a plurality of bias bursts, each of the plurality of bias bursts including bias pulses, each of the plurality of bias bursts having a bias burst turn on time and a bias burst turn off time
Implementation Method 4
Positive ions produced in the plasma volume are accelerated across the plasma sheaths and arrive at the electrodes or wafer with an Ion Energy Distribution Function (IEDF)
Data Source
AI summary
Some embodiments include a plasma system comprising: a plasma chamber, an RF plasma generator, a bias generator, and a controller. The RF plasma generator may be electrically coupled with the plasma chamber and may produce a plurality of RF bursts, each of the plurality of RF bursts including RF waveforms, each of the plurality of RF bursts having an RF burst turn on time and an RF burst turn off time. The bias generator may be electrically coupled with the plasma chamber and may produce a plurality of bias bursts, each of the plurality of bias bursts including bias pulses, each of the plurality of bias bursts having an bias burst turn on time and an bias burst turn off time. In some embodiments the controller is in communication with the RF plasma generator and the bias generator that controls the timing of various bursts or waveforms.