Inductive Plasma Source B-Field Concentrator for Uniformity
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Solution Overview
Problem
In semiconductor manufacturing, capacitively coupled plasmas can damage workpieces and create contaminating particles due to high energy ions and unwanted electrical discharges, while inductive plasmas suffer from power losses and poor plasma uniformity, especially as device geometry decreases.
Innovation Solution
A plasma processing chamber with a lid assembly featuring a nested annular coil and conductive rings, which improves plasma coupling efficiency, reduces sputtering, and allows for tunable plasma profiles by grounding a large conductive surface and using multiple coils with independent power control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitively coupled plasma is used, then plasma generation is achieved, but workpiece damage and contamination occur due to high energy ions and electrical discharges
Solution Approach 1:
The patent replaces the capacitive coupling mechanism (electrodes creating electric fields) with an inductive coupling mechanism (coils creating magnetic fields). The inductive coil generates a time-varying magnetic field that induces eddy currents in the plasma, heating and ionizing the gas without requiring high-voltage electrodes near the workpiece. This substitution eliminates the harmful high-energy ion bombardment and electrical discharges associated with capacitive coupling while maintaining effective plasma generation.
2Loss of energy
If inductive plasma source is used, then power losses are reduced compared to capacitive coupling, but plasma uniformity deteriorates as device geometry decreases
Solution Approach 1:
The patent divides the single inductive coil into multiple segmented coils arranged in an array. Each coil can be independently controlled to generate plasma in specific regions. This segmentation allows for localized plasma generation and independent power control, enabling precise uniformity management across the substrate surface while maintaining the energy efficiency of inductive coupling.
Solution Approach 2:
The patent implements local quality control by allowing each coil segment to operate with independent power levels and timing. This enables the plasma density and characteristics to be optimized for different regions of the substrate, compensating for variations in device geometry and ensuring uniform processing across the entire wafer surface while maintaining low power losses.
3Productivity
If high voltage is applied to inductive coil, then plasma generation efficiency improves, but power losses increase faster than voltage applied
Solution Approach 1:
The patent employs dynamic control of the coil array by independently adjusting the power, frequency, and timing of each coil segment. This dynamic adjustment allows the system to optimize plasma generation efficiency for different process conditions and substrate positions without continuously increasing overall power consumption. The selective activation and power modulation of individual coils enable efficient plasma generation while minimizing unnecessary 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
Enhances plasma uniformity, reduces contamination, and allows for higher voltage application at lower power levels, improving the reliability of semiconductor device manufacturing by minimizing chamber wall sputtering and optimizing plasma density.
Implementation Method 1
An inductive coil is disposed adjacent to a plasma generating region of a processing chamber. The inductive coil projects a magnetic field into the chamber to ionize a gas inside the chamber.
Implementation Method 2
The inductive coil projects a magnetic field into the chamber to ionize a gas inside the chamber.
Implementation Method 3
The electric field can impart very high energies to ions impinging on the workpiece, which can sputter material from the workpiece
Data Source
AI summary
A method and apparatus for plasma processing of substrates is provided. A processing chamber has a substrate support and a lid assembly facing the substrate support. The lid assembly has a plasma source that comprises a coil disposed within a conductive plate, which may comprise nested conductive rings. The coil is substantially coplanar with the conductive plate, and insulated therefrom by an insulator that fits within a channel formed in the conductive plate, or nests within the conductive rings. A field concentrator is provided around the coil, and insulated therefrom by isolators. The plasma source is supported from a conductive support plate. A gas distributor supplies gas to the chamber through a central opening of the support plate and plasma source from a conduit disposed through the conductive plate.