Plasma Processing Apparatus Ion Energy Distribution Control
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Solution Overview
Problem
Current reactive ion etching (RIE) techniques face challenges in narrowing the distribution of ion energy to achieve improved processing accuracy for semiconductor devices, as high-energy ions cause shape degradation and low-energy ions may not contribute effectively to processing, leading to anisotropy issues.
Innovation Solution
A plasma processing apparatus using a first electrode for substrate mounting and a second electrode with a chamber capable of adjusting atmosphere, employing a first electric power source for applying a DC pulse voltage to control self-bias voltage and a second electric power source for applying an RF voltage of a different frequency to generate plasma, ensuring a constant peak-to-peak voltage and synchronized voltage application to narrow ion energy distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If frequency of RF electric power is increased to reduce ion energy distribution, then ion energy distribution narrows, but desired ion energy becomes difficult to obtain
Solution Approach 1:
By using periodic pulsed RF power with controllable pulse width and period, the system can achieve narrow ion energy distribution without requiring high frequency. The pulse timing allows ions to be accelerated to desired energy levels during specific phases, while the periodic nature narrows the distribution by eliminating continuous acceleration variations.
Solution Approach 2:
The patent changes multiple parameters including pulse width, pulse period, and RF voltage amplitude to independently control ion energy and its distribution. This multi-parameter control allows the system to achieve both narrow distribution and desired ion energy levels simultaneously, resolving the trade-off between distribution width and energy level.
2Productivity
If high energy ions are used for etching, then etching rate increases, but shoulder cutting occurs and processed shape degrades
Solution Approach 1:
The periodic pulsed RF power creates discrete ion acceleration events rather than continuous acceleration. This results in a narrower ion energy distribution where ions arrive at the substrate with more uniform energy. The reduced high-energy ion population prevents excessive lateral etching (shoulder cutting) while maintaining sufficient etching rate through controlled ion flux.
Solution Approach 2:
By independently controlling RF voltage amplitude and pulse characteristics, the system optimizes ion energy to achieve the minimum required for effective etching while minimizing excess energy that causes shoulder cutting. The parameter control allows tuning of ion energy distribution to match the specific requirements of the etching process and substrate material.
3Manufacturing precision
If low energy ions are used for etching, then processed shape is maintained, but anisotropy deteriorates and processing effectiveness decreases
Solution Approach 1:
The periodic pulsed RF power ensures that ions are accelerated to sufficient energy levels during the active phases of the pulse cycle, maintaining the energy needed for effective anisotropic etching. The timing and duration of pulses are controlled to ensure ions gain adequate energy for vertical etching while the periodic nature prevents excessive energy accumulation that would cause lateral etching.
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 effectively narrows the ion energy distribution, allowing for precise control of the RIE process, enhancing processing accuracy and etching selectivity while maintaining a high etching rate, thereby improving the quality of semiconductor device fabrication.
Implementation Method 1
a second electric power source device configured to apply a second RF voltage of a second frequency for generating plasma between the first and second electrodes
Implementation Method 2
a first electric power source device configured to apply a first RF voltage for controlling a self-bias voltage generated on the substrate
Implementation Method 3
In physical etching, a potential difference between self-bias voltage generated on a substrate during generation of plasma and the potential of the plasma accelerates positive ions in the plasma. The accelerated positive ions are incident on the substrate and collide with it, so that etching proceeds.
Implementation Method 4
In chemical etching, etching proceeds due to active neutral radicals.
Data Source
AI summary
A plasma processing apparatus for processing a substrate using plasma includes a first electrode configured to mount the substrate, a second electrode disposed to face the first electrode with a predetermined space, a chamber containing the first electrode and the second electrode, the chamber being capable of adjusting an inside atmosphere, a first electric power source device configured to apply a first RF voltage for controlling a self-bias voltage generated on the substrate to the first electrode, the first electric power source device applying a substantially constant width and a substantially constant value in a peak-to-peak voltage of an RF voltage of a first frequency at intervals, and a second electric power source device configured to apply a second RF voltage of a second frequency for generating plasma between the first and second electrodes to one of the first electrode and the second electrode.