Plasma Processing Apparatus Movable Conductor Uniformity
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Solution Overview
Problem
In large-scale plasma processing for semiconductor devices, nonuniform plasma density leads to discrepancies in etching rates across the substrate, resulting in reduced throughput due to higher plasma density at the center than at the peripheral portions of the electrode, and existing solutions either increase energy loss or are inflexible with varying process conditions.
Innovation Solution
A plasma processing apparatus with a movable electrical conductor system that selectively connects or disconnects intermediate conductors to control the distribution of high-frequency power, ensuring uniform plasma density by adjusting the power path and impedance distribution across the electrode surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a large-scale chamber is used to process larger substrates, then the processing capacity is improved, but the plasma density becomes nonuniform between center and peripheral portions
Solution Approach 1:
The patent applies local quality by making the central portion of the high frequency electrode have different electrical properties (higher resistance) compared to the peripheral portion. This is achieved by forming the central portion with a highly resistive material or by creating a resistive film pattern, which locally modifies the electric field distribution to compensate for the natural tendency of plasma density to concentrate at the center in large-scale chambers.
2Manufacturing precision
If the central portion of the electrode is made of highly resistive material to correct plasma nonuniformity, then the plasma density uniformity is improved, but the energy loss increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the resistance of the intermediate conductor through temperature control. The resistance is varied to optimize the balance between plasma density uniformity and energy loss, allowing the system to adapt to different processing conditions and substrate sizes without being fixed to a single resistance value.
Solution Approach 2:
The patent introduces dynamics by making the intermediate conductor's resistance adjustable rather than fixed. The resistance can be changed in response to process conditions, substrate size, and plasma density requirements, allowing the system to dynamically optimize performance and minimize energy loss while maintaining plasma uniformity.
3Manufacturing precision
If the electrode structure is modified to improve plasma uniformity, then the plasma density distribution is improved, but the device complexity increases
Solution Approach 1:
The patent introduces an intermediate conductor as a mediator between the high frequency power supply and the main electrode. This intermediate conductor with adjustable resistance simplifies the overall control by providing a single point of adjustment that affects the entire electrode's current distribution, rather than requiring complex modifications to the electrode structure itself.
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 uniformity and throughput by dynamically managing plasma density distribution, reducing energy loss and adapting to various process conditions, thereby improving the consistency of substrate etching.
Implementation Method 1
electrons accelerated by the high frequency electric field generated between the electrodes, and secondary electrons and thermal electrons emitted from the electrodes collide with and ionize molecules of processing gas, thereby generating a plasma of the processing gas
Implementation Method 2
the central portion of the main surface (a surface to which a plasma contacts) of the electrode to which a high frequency power supply is connected, is formed with the highly resistive material which dissipates larger high frequency power by joule heat
Data Source
AI summary
A plasma processing apparatus performing a plasma processing to a substrate includes a processing vessel having a vacuum exhaustible processing chamber; a mounting table serving as a lower electrode for mounting thereon the substrate in the processing chamber; a circular ring member arranged to surround a periphery of the substrate whose radial one end portion is supported by the mounting table; an upper electrode arranged above the lower electrode to face same; and a power feed for supplying the mounting table with a high frequency power. The plasma processing apparatus further includes a first intermediate electrical conductor supporting a middle portion of the circular ring member; and a first movable electrical conductor which is selectively electrically connected or disconnected to the power feed; and a second intermediate electrical conductor supporting a radial opposite end portion of the circular ring member.