Edge Ring RF Voltage Control for Plasma Uniformity
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Solution Overview
Problem
Current plasma processing technologies face challenges in maintaining uniformity during substrate processing due to edge effects and polymer deposition issues, leading to defective devices and reduced yield, particularly as substrate sizes increase and feature sizes decrease.
Innovation Solution
The method involves providing low frequency RF power to an edge ring in a plasma processing system, allowing independent control of the edge ring potential to match the substrate's DC potential, optimizing equipotential lines and ion angular distribution, and using segmented RF power delivery and additional controls like differential gas flow and electrostatic clamping to enhance uniformity and prevent polymer flaking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If substrate size is increased to maximize real estate utilization, then productivity increases, but manufacturing precision deteriorates due to edge effects causing non-uniform process results
Solution Approach 1:
The patent applies local quality by independently controlling the edge ring potential from the substrate potential. The edge ring is equipped with separate RF power delivery and DC bias control, allowing the edge region to have different electrical characteristics than the substrate center. This local differentiation compensates for edge effects and maintains uniform plasma processing across the entire substrate surface, enabling larger substrate sizes without sacrificing process uniformity.
2Productivity
If feature size is reduced to increase device density, then productivity increases, but manufacturing precision deteriorates due to increased edge effects
Solution Approach 1:
By providing independent control of the edge ring potential through separate RF power delivery and DC bias, the system creates locally optimized conditions at the substrate edge. This allows the edge region to maintain plasma parameters similar to the center, ensuring that reduced feature sizes are processed uniformly across the entire substrate surface, thereby maintaining manufacturing precision while increasing device density.
3Ease of operation
If polymer deposition control is relaxed during etch processes, then ease of operation increases, but harmful factors increase due to polymer flaking onto adjacent substrates
Solution Approach 1:
The patent changes the electrical parameters at the substrate edge by independently controlling the edge ring potential. By adjusting the DC bias and RF power to the edge ring, the plasma chemistry and polymer deposition characteristics are modified at the edge region. This parameter control prevents excessive polymer accumulation and flaking onto adjacent substrates, reducing harmful effects while maintaining operational simplicity through automated control.
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 improves azimuthal uniformity and reduces the risk of polymer deposition on adjacent substrates, maintaining process uniformity and increasing device yield by controlling plasma species and chemistry around the substrate edge.
Implementation Method 1
delivering a low frequency RF power to an edge ring (312) surrounding a substrate (306)
Implementation Method 2
generating a plasma within the plasma processing chamber to process the substrate
Implementation Method 3
an electrostatic chuck (ESC) (308), which also serves as a powered electrode
Data Source
AI summary
In a plasma processing chamber, a method for processing a substrate is provided. The substrate is disposed above a chuck and surrounded by an edge ring, which is electrically isolated from the chuck. The method includes providing first RF power to the chuck. The method also includes providing an edge ring RF voltage control arrangement, which is coupled to the edge ring to provide second RF power to the edge ring. The second RF power being delivered to the edge ring has a frequency of about 20 KHz to about 10 MHz, resulting in the edge ring having anedgering potential. The method further includes generating a plasma within the plasma processing chamber to process the substrate, the substrate being processed while the edge ring RF voltage control arrangement is configured to control the second RF power to the edge ring such that a predefined potential difference is maintained between the edge ring and the substrate.