Shielded Lid Heater Segmentation for ICP Power Coupling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional inductively coupled plasma (ICP) process reactors face challenges with RF coupling efficiency and substrate processing uniformity due to power losses and non-uniformities caused by the magnetic field interactions between ICP coils and shielded heaters, particularly in out-of-phase modes.
Innovation Solution
A plasma processing apparatus with a shielded lid heater design featuring an annular member and radially extending spokes that minimize RF power losses and enhance power coupling efficiency by positioning the shield in areas with reduced magnetic field strength, effectively reducing current induction and M-shape signatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a closed loop aluminum shield is used to prevent RF coupling interference with AC/DC heaters, then RF shielding effectiveness is improved, but power coupling efficiency deteriorates due to induced currents in the shield
Solution Approach 1:
The closed loop aluminum shield is segmented into radial spokes that are electrically isolated from each other. This segmentation breaks the continuous conductive path that would otherwise allow large induced currents to flow, thereby reducing RF power losses while maintaining RF shielding effectiveness. The spokes are positioned to provide necessary shielding without forming a complete electrical loop.
Solution Approach 2:
The shield structure is designed with varying properties in different regions. The radial spokes provide localized shielding where needed, while the gaps between spokes allow RF energy to pass through to the substrate. This local differentiation optimizes both shielding performance and power coupling efficiency by placing shielding elements only where interference occurs without creating continuous current paths.
2Manufacturing precision
If out-of-phase mode is used in dual mode ICP coils to eliminate M-shape signatures, then substrate uniformity is improved, but RF power losses increase due to significant coupling in the out-of-phase case
Solution Approach 1:
The segmented radial spoke shield acts as an intermediary element between the ICP coils and the substrate. It modifies the RF field distribution in a controlled manner, allowing the out-of-phase coil mode to be used for uniformity control while the shield structure itself manages the coupling effects. The spokes provide a pathway to control field distribution without creating the harmful continuous current loops that would cause excessive power losses.
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 solution improves power coupling efficiency, reduces RF power losses, and enhances substrate processing uniformity by minimizing current induction in the shield, leading to better control over plasma formation and etch patterns.
Implementation Method 1
When radio frequency (RF) current is fed to the inductive coils via an RF feed structure from an RF power source, an inductively coupled plasma can be formed inside the chamber from an electric field generated by the inductive coils
Implementation Method 2
In order to eliminate RF coupling of the ICP source to the AC/DC powered heated elements, the heaters are embedded within a aluminum or any conductor shield to prevent any interference of the RF to the AC/DC heaters
Data Source
AI summary
Apparatus for processing substrates are provided herein. In some embodiments, plasma processing apparatus may include a process chamber having a dielectric lid and an interior processing volume beneath the dielectric lid, a first RF coil to couple RF energy into the processing volume, and an RF shielded lid heater coupled to a top surface of the dielectric lid. The RF shielded lid heater may include an annular member, and a plurality of spokes, wherein each of the plurality of spokes includes one of (a) a first portion that extends downward from the annular and couples the annular member to a second portion of the spoke that extends radially inward, or (b) a first portion that extends radially outward from the annular member.