Grounded Coupling Ring for Plasma Harmonic Control in Etching
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Solution Overview
Problem
The challenge in semiconductor manufacturing is the non-uniform plasma density distribution during plasma treatment, leading to uneven etching rates across the substrate, particularly in the central region, due to the limitations of focus and edge rings in controlling plasma harmonics.
Innovation Solution
A substrate treating apparatus with a support unit featuring an edge ring and a coupling ring, along with a cable connected to a ground, allows for adjustable impedance to control plasma harmonics by varying the cable length or using a circuit unit to adjust impedance, thereby enhancing plasma uniformity and etching rate control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a focus ring or edge ring is used to control plasma in the edge region, then the initial plasma state in the edge region can be controlled, but the plasma density distribution remains non-uniform and the central region plasma cannot be controlled
Solution Approach 1:
The invention divides the plasma control function into two independent parts: edge ring for edge region control and focus ring for central region control. This segmentation allows each ring to independently control plasma in its respective region, achieving uniform plasma density distribution across the entire substrate surface without increasing overall system complexity
Solution Approach 2:
The invention applies different control mechanisms to different regions of the substrate. The edge ring specifically controls plasma in the edge region while the focus ring controls plasma in the central region. This local quality approach ensures that each region receives optimized plasma control tailored to its specific requirements, resolving the non-uniformity issue
2Manufacturing precision
If the cable length is increased to adjust impedance, then harmonic control capability is improved, but the device complexity and space requirements increase
Solution Approach 1:
The invention makes the cable length adjustable rather than fixed, allowing dynamic optimization of impedance for different harmonic control requirements. The variable cable length mechanism enables precise harmonic control while adapting to different operational conditions, achieving high precision without requiring excessively long cables in all cases
Solution Approach 2:
The invention changes the cable length parameter to optimize impedance matching for harmonic control. By adjusting the cable length, the system can achieve desired impedance values (e.g., 50Ω to 1000Ω) for effective harmonic removal, balancing control precision with reasonable cable length requirements
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 apparatus effectively controls plasma harmonics, ensuring uniform plasma density and higher etching rates across the substrate, particularly in the central region, by selectively removing harmonic components.
Implementation Method 1
an RF signal is applied to an electrostatic chuck to generate plasma
Implementation Method 2
The plasma refers to an ionized gas state comprising ions, electrons, radicals, or the like. The plasma is generated by a very high temperature, a strong electric field, or an RF (radio frequency) electromagnetic field.
Implementation Method 3
the cable is provided in a length having a low impedance to remove a harmonic component of the plasma generated in in the processing chamber
Implementation Method 4
the cable is provided in a length to have an impedance of about 50Ω to 1000Ω
Data Source
AI summary
A substrate treating apparatus includes a processing chamber having an inner processing space, a support unit supporting a substrate in the processing space, a gas supply unit supplying processing gas into the treatment space, and a RF power for supplying an RF signal to excite the processing gas into a plasma state. The support unit includes an edge ring surrounding the substrate, a coupling ring disposed under the edge ring and including an electrode therein, and a cable connected to the electrode. The end of the cable is grounded.