Dual-Waveguide Plasma Layout for Tunable Etching Density
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Solution Overview
Problem
Plasma processing apparatuses face non-uniform plasma density distribution across the process chamber, leading to non-uniform etching rates on semiconductor substrates, which is not adequately addressed by existing technologies, particularly in achieving 'centrally high density', 'circumferentially high density', or 'uniform density' distributions.
Innovation Solution
The apparatus features a microwave power divider that splits the microwave power into inner and outer waveguides with a dielectric power gate to regulate microwave power, allowing for the formation of circularly polarized waves and controlling plasma density distribution by adjusting the insertion length of the power gate, enabling flexible adjustment of plasma density to desired etching conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single microwave power source is introduced into the process chamber by means of a branched rectangular waveguide, then the non-uniformity of plasma distribution in a process chamber for large-diameter substrate is improved, but the annihilation of ions and radicals due to solid surface reactions on the wall surfaces of the process chamber cannot be addressed
Solution Approach 1:
The rectangular waveguide is divided into an upper rectangular waveguide and a lower rectangular waveguide that are vertically arranged and extend in the width direction of the process chamber. This segmentation allows independent control of microwave power distribution to different regions, enabling separate optimization for plasma uniformity and compensation for wall surface effects.
Solution Approach 2:
Different regions of the process chamber are provided with different microwave power intensities by adjusting the insertion depth of dielectric members in each waveguide. The upper and lower waveguides can independently regulate power distribution to create locally optimized plasma density patterns that compensate for wall surface annihilation effects.
2Manufacturing precision
If two rectangular waveguides are orthogonally arranged to control the phase of inputted microwaves, then the in-plane uniformity of etching surface is improved, but the problem concerning higher plasma density at the center of the process chamber remains
Solution Approach 1:
Dielectric members with adjustable insertion depth are placed in each rectangular waveguide, allowing dynamic regulation of microwave power intensity. By independently adjusting the insertion depth in upper and lower waveguides, the system can dynamically control plasma density distribution to achieve desired patterns (centrally high, circumferentially high, or uniform) while maintaining etching uniformity.
3Manufacturing precision
If microwave power is increased above the center of the processed substrate, then thin film etching with convex shape distribution is improved, but plasma density at the center becomes excessively high
Solution Approach 1:
The insertion depth of dielectric members in the upper and lower rectangular waveguides is adjusted to change the microwave power intensity parameter. By independently controlling the power distribution from upper and lower directions, the system can create optimized plasma density patterns that provide sufficient power to the substrate center for convex film distribution while preventing excessive plasma density accumulation.
4Manufacturing precision
If microwave power is reduced at the center of the processed substrate, then thin film etching with concave shape distribution is improved, but plasma density becomes insufficient at the center
Solution Approach 1:
The insertion depth of dielectric members is adjusted to reduce microwave power intensity at the substrate center. By coordinating the power reduction from both upper and lower waveguides, the system can create plasma density patterns suitable for concave film distribution while maintaining sufficient plasma density for effective etching.
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 configuration reduces plasma distribution non-uniformity and allows for precise control of plasma density distribution, achieving 'centrally high density', 'circumferentially high density', or 'uniform density' as needed, enhancing etching uniformity and process control.
Implementation Method 1
a rectangular waveguide for transmitting microwaves; a circular waveguide connected to the rectangular waveguide and transmitting the microwaves to the process chamber
Implementation Method 2
a plasma processing apparatus which produces plasma by means of electromagnetic waves
Implementation Method 3
a dielectric power gate to regulate microwave power, allowing for the formation of circularly polarized waves and controlling plasma density distribution by adjusting the insertion length of the power gate
Implementation Method 4
allowing for the formation of circularly polarized waves
Implementation Method 5
The apparatus features a microwave power divider that splits the microwave power into inner and outer waveguides
Data Source
AI summary
A plasma processing apparatus adapted to reduce non-uniformity of plasma distribution in a process chamber and to adjust the plasma distribution to “centrally high density”, “circumferentially high density”, or “uniform density” in accordance with a desired etching process, a process chamber; a radio frequency power source; a rectangular waveguide; and a circular waveguide connected to the rectangular waveguide, in which the rectangular waveguide includes an upper rectangular waveguide and a lower rectangular waveguide formed by vertically dividing the rectangular waveguide; and a cutoff section which cuts off the microwave frequency power and which has a dielectric body. The circular waveguide includes an inner waveguide connected to the upper rectangular waveguide and formed inside; and an outer waveguide connected to the lower rectangular waveguide and formed on an outer side of the inner waveguide. The cutoff section has a width narrower than those of the rectangular waveguides except the cutoff section.