Microwave Waveguide Layout for Plasma Density Control in Etching
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Solution Overview
Problem
Plasma processing apparatuses face challenges with non-uniform plasma density distribution, leading to inconsistent etching rates and potential charge-up damage during semiconductor manufacturing, due to fixed microwave power ratios and limited control over plasma density.
Innovation Solution
A plasma processing apparatus with a microwave power control system that adjusts the ratio of microwave power between inner and outer waveguides by varying the liquid dielectric level, allowing for flexible control of plasma density distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single microwave source with fixed waveguide arrangement is used, then the device complexity is reduced, but the adaptability of microwave power ratio adjustment is limited
Solution Approach 1:
The patent introduces a variable dielectric constant material that can dynamically change its dielectric constant to adjust the microwave power ratio between different waveguides. This dynamic adjustment capability allows the system to adapt to different processing requirements without changing the physical waveguide arrangement, thus resolving the contradiction between device complexity and adaptability.
Solution Approach 2:
The patent changes the dielectric constant parameter of the material in the waveguide to control the microwave power distribution. By varying the dielectric constant, the system can flexibly adjust the power ratio delivered to different regions of the processing chamber, enabling adaptability without increasing structural complexity.
2Quantity of substance
If microwave power is concentrated at the center of the processing chamber, then the plasma density at the center increases, but the plasma density uniformity across the chamber deteriorates
Solution Approach 1:
The patent applies local quality by using variable dielectric constant materials in specific waveguides to control microwave power distribution to different regions. This allows selective enhancement of plasma density in specific areas (such as the center) while maintaining overall uniformity through independent control of each waveguide's power contribution.
Solution Approach 2:
The system dynamically adjusts the dielectric constant of materials in different waveguides to balance plasma density distribution. By changing the dielectric constant in real-time, the system can compensate for natural plasma density gradients and achieve uniform plasma distribution across the processing chamber.
3Device complexity
If the microwave power ratio is fixed by waveguide arrangement, then the device complexity is reduced, but the ability to control plasma density distribution for different processing conditions is limited
Solution Approach 1:
The patent changes the electrical parameter (dielectric constant) of materials within the waveguide system to control plasma density distribution. This parameter-based control mechanism provides flexibility in adapting to different processing conditions without requiring complex reconfiguration of the waveguide physical structure.
Solution Approach 2:
The patent uses replaceable dielectric inserts or materials that can be easily changed or adjusted. These materials serve as a simple, low-cost means to modify microwave power distribution characteristics, enabling adaptability without investing in complex adjustable waveguide structures.
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
Enables dynamic adjustment of plasma density for uniform etching and reduces charge-up damage by allowing precise control of microwave power distribution within the processing chamber.
Implementation Method 1
a first circular waveguide filled with a liquid dielectric
Implementation Method 2
when changing gas conditions or the substrate, the dielectric is replaced with a dielectric having a different relative permittivity
Implementation Method 3
a microwave of 2.45 GHz emitted from a magnetron is propagated through a rectangular waveguide and a circular waveguide, and introduced into a processing chamber in which a magnetic field is formed... by an electric field generated by the microwaves and a magnetic field formed in a direction perpendicular to the electric field, the electron cyclotron resonance is generated
Implementation Method 4
The plasma excites molecules or atoms of a processing gas by utilizing a collision of electrons with the molecules or the atoms of the processing gas, and generates ions and radicals
Implementation Method 5
generates ions and radicals
Data Source
AI summary
In order to enable plasma density distribution control having a high degree of freedom to solve problems of not only in-plane uniformity of an etching processing but also a reduction of a charge-up damage, a plasma processing apparatus includes: a vacuum chamber provided with a plasma processing chamber that plasma-processes a substrate inside and is able to exhaust the inside of this plasma processing chamber to a vacuum; and a microwave power supply unit that is provided with a microwave source and a circular waveguide and supplies, via the circular waveguide, a microwave power oscillated from the microwave source to the vacuum chamber, in which the microwave power supply unit is configured by arranging a plurality of waveguides, which are coaxially and concentrically arranged with the circular waveguide and have different dielectric constants inside, between the circular waveguide and the vacuum chamber.