Dielectric Window Spatial Variation for ICP Plasma Uniformity
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Solution Overview
Problem
In inductively coupled plasma (ICP) processing reactors, the M-shaped etch rate profile due to in-phase coil currents limits uniformity, and out-of-phase operation to mitigate this requires higher power, which can be costly and unstable, leading to reduced ion flux and throughput.
Innovation Solution
Modifying the dielectric window by varying its thickness or dielectric coefficient between the coils to create a null region in power coupling, mimicking the effect of out-of-phase operation without increasing power, thereby controlling the plasma profile and enhancing uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If out-of-phase coil currents are used to eliminate the M-shaped etch rate profile, then uniformity is improved, but RF power requirements increase significantly and operational stability deteriorates
Solution Approach 1:
The patent applies local quality by creating a localized null region in the power coupling profile between the coils through out-of-phase operation. This localized modification of the electromagnetic field distribution eliminates the M-shaped etch rate profile at the substrate level while maintaining in-phase operation elsewhere in the system, avoiding the need for high-power RF generators and capacitive coupling instability
Solution Approach 2:
The patent changes the phase parameter of the coil currents from in-phase to out-of-phase operation. This parameter change creates destructive interference in the electric field between the coils, forming a null region that flattens the plasma profile and eliminates the M-shaped etch rate profile, achieving uniformity without the drawbacks of high power requirements
2Manufacturing precision
If out-of-phase operation is implemented to flatten the plasma profile, then center to edge uniformity is improved, but ion flux to the substrate is reduced
Solution Approach 1:
The patent creates a localized null region between the coils through out-of-phase operation, which flattens the plasma profile at the substrate level. This localized modification allows the plasma to be distributed more uniformly across the substrate surface while maintaining adequate ion flux by confining the null region to the inter-coil area rather than the entire processing volume
3Productivity
If higher RF power is supplied to increase etch rate in out-of-phase operation, then throughput is improved, but equipment cost and complexity increase
Solution Approach 1:
The patent changes the phase parameter of the coil currents to create a null region that flattens the plasma profile. This parameter change allows maintenance of etch rate and throughput without requiring higher RF power, as the out-of-phase operation itself creates the conditions for uniform plasma distribution and adequate ion flux to the substrate
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 suppresses the M-shaped profile, maintaining uniformity and throughput while avoiding the need for high-power RF generators, stabilizing the plasma and ion flux, and extending the operational window.
Implementation Method 1
a dielectric window for an inductively coupled plasma reactor includes: a body including a first side, a second side opposite the first side, an edge, and a center, wherein the dielectric window has a dielectric coefficient that varies spatially
Implementation Method 2
one or more inductive coils disposed above the lid to inductively couple RF energy into and to form a plasma in the processing volume
Implementation Method 3
one or more inductive coils disposed above the lid to inductively couple RF energy into and to form a plasma in the processing volume
Implementation Method 4
Through diffusion, the overall plasma profile at the substrate level can be flattened, eliminating or reducing the M-shape signature
Data Source
AI summary
Embodiments of inductively coupled plasma (ICP) reactors are provided herein. In some embodiments, a dielectric window for an inductively coupled plasma reactor includes: a body including a first side, a second side opposite the first side, an edge, and a center, wherein the dielectric window has a dielectric coefficient that varies spatially. In some embodiments, an apparatus for processing a substrate includes: a process chamber having a processing volume disposed beneath a lid of the process chamber; and one or more inductive coils disposed above the lid to inductively couple RF energy into and to form a plasma in the processing volume above a substrate support disposed within the processing volume; wherein the lid is a dielectric window comprising a first side and an opposing second side that faces the processing volume, and wherein the lid has a dielectric coefficient that spatially varies to provide a varied power coupling of RF energy from the one or more inductive coils to the processing volume.