Peripheral RF Feed for Plasma Etch Uniformity
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Solution Overview
Problem
Non-uniform etching in wafer processing leads to yield issues, particularly as critical dimensions shrink and wafer sizes increase, necessitating stringent control of non-uniformity to enable advanced technology nodes in a cost-effective manner.
Innovation Solution
A peripheral RF feed and symmetric RF return system is implemented using a chuck assembly with a hollow RF feed that delivers RF power to the periphery of a facility plate, bypassing central components and utilizing a grounded shield for symmetric RF delivery, ensuring high azimuthal uniformity and minimizing interference from facility components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a traditional center RF feed system is used, then the RF power can be delivered to the substrate, but azimuthal non-uniformity occurs leading to non-uniform etching
Solution Approach 1:
The RF feed system is segmented from the center to the periphery. The hollow RF feed delivers RF power to the periphery of the facility plate, dividing the RF delivery path into peripheral contact points rather than a single central point, thereby achieving more uniform azimuthal power distribution across the substrate surface
Solution Approach 2:
The RF feed contact point is moved from the vertical dimension (center of plate) to the peripheral dimension (edge of plate). This dimensional shift allows the RF power to be applied at multiple azimuthal locations simultaneously through the hollow structure, eliminating the single-point azimuthal non-uniformity of traditional center feeds
2Ease of manufacture
If facility components are placed in the center of the facility plate, then they can be easily accessed and connected, but they interfere with RF delivery and cause non-uniformity
Solution Approach 1:
The RF delivery function is extracted from the central region where facility components are located. The hollow RF feed contacts the periphery of the facility plate, removing the RF power delivery path from the interference zone of central facility components such as electrostatic chuck connections and gas distribution systems
Solution Approach 2:
The hollow RF feed acts as an intermediary structure that bypasses the central facility components. It delivers RF power through its wall structure to the periphery of the facility plate without requiring direct connection through the center, thus mediating between the RF source and the substrate while avoiding interference from central components
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 significantly reduces azimuthal non-uniformity, maintaining low levels across a range of RF power settings and improving wafer processing consistency, as demonstrated by reduced etch rate variations compared to traditional center RF feed systems.
Implementation Method 1
A hollow RF feed is configured to deliver RF power to a facility plate of an electrostatic chuck assembly
Implementation Method 2
an electrostatic chuck having a substrate support surface on a first side
Implementation Method 3
immersing silicon substrates (wafers) containing regions of doped silicon in chemically-reactive plasmas, where the submicron device features (e.g., transistors, capacitors, etc.) are etched onto the surface
Data Source
AI summary
A chuck assembly for plasma processing, including: an electrostatic chuck having a substrate support surface on a first side; a facility plate coupled to the electrostatic chuck on a second side; a RF feed defined by a first portion contacting a periphery of the facility plate and a second portion coupled to the first portion, the second portion extending away from the chuck assembly, the first portion being a bowl-shaped section, wherein the second portion connects to the first portion at an opening defined in the bowl-shaped section; wherein the first portion of the RF feed contacts the periphery of the facility plate at a circumference circumference having a radius greater than one-half of a radius of the facility plate, the radius of the circumference being less than the radius of the facility plate; a grounded shield disposed below and surrounding at least a portion of the bowl-shaped section.