Plasma Processing Substrate Support Potential Control
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Solution Overview
Problem
In plasma processing apparatuses, the tilting of etching holes occurs due to non-vertical electric fields and potential differences between the substrate and edge ring, leading to global tilting of the plasma sheath, which is challenging to control without increasing space occupation and design costs.
Innovation Solution
A plasma processing apparatus with a substrate support that includes separate regions for the substrate and edge ring, featuring bias electrodes and impedance adjusting electrodes connected through an impedance adjusting mechanism, allowing independent control of potentials on both sides, thereby adjusting the electric field direction and etching rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a variable capacitor is connected to an annular electrode to increase RF voltage in the edge ring, then the edge ring erosion is improved, but the device complexity and space occupation increase
Solution Approach 1:
The patent combines the edge ring restoration function with the existing annular electrode structure by integrating a DC power supply directly into the electrode system. This merging approach eliminates the need for separate variable capacitors and complex RF voltage adjustment mechanisms, thereby restoring the edge ring through direct DC potential control while maintaining apparatus simplicity
Solution Approach 2:
The patent extracts the DC potential control function from the complex RF voltage adjustment system. By applying DC potential directly to the annular electrode, the system separates the edge ring restoration function from the RF matching network, eliminating the need for variable capacitors and complex impedance matching components
2Measurement precision
If DC potential is applied to the annular electrode to restore the edge ring, then the control precision is improved, but the device complexity increases
Solution Approach 1:
The patent implements self-service by using the annular electrode structure to serve dual purposes: maintaining its original RF function while simultaneously providing DC potential control for edge ring restoration. The DC power supply connects directly to the existing electrode, allowing it to self-adjust the potential distribution without requiring additional control mechanisms or complex circuitry
Solution Approach 2:
The annular electrode is designed with multi-functionality, serving both as an RF electrode for plasma generation and as a DC potential control electrode for edge ring restoration. This universal design allows a single component to perform multiple functions, eliminating the need for separate DC and RF electrode systems and reducing overall device complexity
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 solution enables precise control of potentials on the substrate and edge ring sides, reducing tilting and improving the uniformity of plasma sheath distribution, enhancing the etching process without increasing the apparatus's size or design complexity.
Implementation Method 1
the thickness of a plasma sheath may vary depending on the potential difference between a substrate (hereinafter, also referred to as a wafer) and an edge ring. Therefore, the direction of an electric field is not vertical to the substrate
Implementation Method 2
an impedance adjusting mechanism connected to at least one of the first impedance adjusting electrode and the second impedance adjusting electrode
Data Source
AI summary
A plasma processing apparatus includes: a chamber; a bias power supply that generates an electric bias; a substrate support that supports a substrate and an edge ring in the chamber, and including a first region configured to hold the substrate, a second region provided to surround the first region and hold the edge ring, a first bias electrode provided in the first region to receive the electric bias, a first impedance adjusting electrode provided in the first region to be grounded, a second bias electrode provided in the second region to receive the electric bias, and a second impedance adjusting electrode provided in the second region to be grounded; an impedance adjusting mechanism connected to at least one of the first impedance adjusting electrode and the second impedance adjusting electrode; and an electric path connecting the bias power supply, the first bias electrode, and the second bias electrode.