Electrostatic Chuck Current Loops for Plasma Uniformity
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Solution Overview
Problem
Conventional substrate support assemblies face challenges in achieving uniformity during plasma processing, particularly in film thickness, etch chamber, and magnetic field-induced non-uniformities, leading to variations in etch rates and critical dimension control.
Innovation Solution
Incorporating a plurality of current loops in the substrate support assembly that generate small magnetic fields, allowing for localized adjustments to plasma processing rates without damaging the semiconductor substrate, thereby compensating for film thickness and magnetic field-induced non-uniformities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional substrate support assemblies are used, then the basic plasma processing function is maintained, but non-uniformities in film thickness, etch chamber, and magnetic field-induced variations occur leading to poor etch rate uniformity and critical dimension control
Solution Approach 1:
The substrate support assembly incorporates multiple independent magnetic field generators (coil assemblies) positioned at different azimuthal locations around the substrate. Each coil can be independently controlled to generate localized magnetic fields that correct specific non-uniformities in different regions of the substrate, enabling spatially-resolved etch rate control without requiring complete system redesign
Solution Approach 2:
The magnetic field generation system is divided into multiple discrete coil assemblies rather than using a single uniform magnetic field source. This segmentation allows independent control of magnetic field strength and polarity in different azimuthal zones, enabling targeted correction of local etch rate non-uniformities while maintaining overall system simplicity
2Manufacturing precision
If strong magnetic fields are applied to correct plasma non-uniformities, then etch rate uniformity improves, but damage to semiconductor circuits on the substrate may occur
Solution Approach 1:
Instead of applying a uniform strong magnetic field across the entire substrate, the system uses multiple independently controlled coil assemblies to generate localized magnetic fields only in regions where non-uniformities are detected. This allows correction of film thickness variations and etch rate non-uniformities while keeping magnetic field exposure to sensitive circuit areas minimal or zero
Solution Approach 2:
The system applies magnetic fields at optimized strength levels - sufficient to correct plasma non-uniformities and improve etch rate uniformity, but controlled to remain below damage thresholds for semiconductor circuits. The partial action approach uses just enough magnetic field strength to achieve the desired correction without excessive exposure that would harm sensitive devices
3Measurement precision
If multiple independently controllable magnetic field generators are added to correct azimuthal non-uniformities, then etch rate control precision improves, but system complexity and cost increase
Solution Approach 1:
The system implements multiple coil assemblies with independent control capabilities, allowing precise adjustment of magnetic field parameters in different azimuthal zones. This enables targeted correction of critical dimension non-uniformities in specific regions of the substrate while maintaining manageable control complexity through modular architecture
Solution Approach 2:
The system incorporates sensors to detect plasma parameters and etch rate variations, using this feedback information to dynamically adjust the magnetic field strength and distribution from the coil assemblies. This closed-loop control enables high precision critical dimension uniformity while automating the complexity of coordinating multiple magnetic field generators
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 effectively corrects azimuthal etch rate non-uniformities by applying localized magnetic fields, resulting in improved uniformity and precision in plasma processing, such as etching, by reducing etch rate variations and enhancing critical dimension control.
Implementation Method 1
Incorporating a plurality of current loops in the substrate support assembly that generate small magnetic fields
Data Source
AI summary
An electrostatic chuck includes an embedded electrode receiving a first voltage to electrostatically attract a semiconductor substrate to the electrostatic chuck. A plurality of current loops are disposed in at least one of the electrostatic chuck and an edge ring surrounding the electrostatic chuck. The current loops are laterally spaced apart. Each current loop is a wire formed into a loop. One or more DC power sources are electrically connected to the current loops. A controller supplies the first voltage to the embedded electrode, supplies a DC current to the current loops from the power sources, and controls the power sources. Each current loop is independently operable and generates a localized DC magnetic field proximate to the semiconductor substrate on receiving the DC current during plasma processing of the semiconductor substrate to adjust the plasma processing of the semiconductor substrate. The localized DC magnetic field does not generate plasma.