Processing Chamber Capacitance Balancing for Edge Ring Arcing
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Solution Overview
Problem
Plasma process chambers experience issues with ring walking and electrical arcing due to varying capacitances, particularly when using radiofrequency (RF) power or pulsed voltage technology (PVT), leading to non-uniform processing and potential chamber damage.
Innovation Solution
Implementing methods and systems to balance capacitance within the processing chamber by adjusting the capacitance of the edge ring to match that of the substrate, using fixed or variable capacitors, and potentially incorporating a sliding ring to adjust capacitive coupling, thereby stabilizing the electric field distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the edge ring capacitance is not matched to the substrate capacitance, then the processing chamber can operate with simple structure, but ring walking and electrical arcing issues occur leading to non-uniform processing and potential chamber damage
Solution Approach 1:
A balance capacitor is introduced as an intermediary component between the edge ring and ground to match the capacitance value to the substrate capacitance. This mediator component enables capacitance balancing without requiring complex structural modifications to the chamber, thereby improving processing stability while maintaining relatively simple device architecture.
Solution Approach 2:
The capacitance value of the balance capacitor is specifically selected to match the substrate capacitance parameter. By changing and optimizing the capacitance parameter of the edge ring circuit through the balance capacitor, the system achieves uniform electric field distribution and prevents ring walking and arcing issues.
2Adaptability or versatility
If fixed capacitors are used for capacitance balancing, then the device structure is simple, but the capacitance matching is not adjustable for different processing conditions
Solution Approach 1:
A variable capacitor is used instead of a fixed capacitor, allowing the capacitance value to be dynamically adjusted to match different substrate capacitance values under various processing conditions. This dynamic adjustment capability enables the system to adapt to different gases, powers, and frequencies while maintaining capacitance balance and preventing ring walking.
Solution Approach 2:
The variable capacitor allows real-time adjustment of the capacitance parameter to match the substrate capacitance under different processing conditions. This parameter adaptability ensures optimal performance across various plasma processing scenarios without requiring complex reconfiguration of the entire system.
3Reliability
If the edge ring area is large relative to the substrate area, then the chamber structure is simplified, but capacitance mismatch causes ring walking and arcing
Solution Approach 1:
The balance capacitor acts as an intermediary that compensates for the large edge ring area by providing the appropriate capacitance value. This allows the edge ring to maintain its beneficial large area for plasma confinement and uniformity while preventing ring walking and arcing through proper capacitance matching.
Solution Approach 2:
By adjusting the capacitance parameter of the balance capacitor to match the substrate capacitance, the system can maintain a large edge ring area without suffering from capacitance mismatch issues. This parameter optimization enables both large edge ring area benefits and reliable operation.
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 film uniformity, reduces particulate contamination, improves process control, and minimizes arcing, resulting in more stable and efficient plasma processing.
Implementation Method 1
a first capacitance is produced between the electrode and the substrate, an edge ring disposed adjacent the substrate, the edge ring having a second capacitance, and at least one balance capacitor disposed within the processing chamber to match the second capacitance of the edge ring to the first capacitance between the electrode and the substrate
Implementation Method 2
a sliding ring disposed adjacent the edge ring to adjust capacitive coupling characteristics resulting from the at least one capacitor
Implementation Method 3
Electromagnetic energy (e.g., radio frequency) is applied to the injected gas to excite the gas into a plasma state
Implementation Method 4
The plasma releases ions that bombard the surface of the substrate to remove contaminants and/or material from the substrate
Data Source
AI summary
Aspects generally relate to methods and systems for modulating capacitance values of different components within a processing chamber. The processing chamber includes an electrode driven by a power source coupled to a substrate, where a first capacitance is produced between the electrode and the substrate, an edge ring disposed adjacent the substrate, the edge ring having a second capacitance, and at least one capacitor disposed within the processing chamber to match the second capacitance of the edge ring to the first capacitance between the electrode and the substrate. In one example, the at least one capacitor is a fixed capacitor. In another example, the at least one capacitor is a variable capacitor. Components of the processing chamber may be powered by either a radiofrequency source or a pulse generator.