Upper Electrode Compensation Plate for Uniform CCP Plasma
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Solution Overview
Problem
Conventional plasma devices face challenges in achieving uniform plasma density distribution due to non-uniform electric fields and standing wave effects, leading to contamination and reduced etching selectivity, especially when high-frequency RF power is used, which can cause over-decomposition of active species and damage to electrostatic chucks.
Innovation Solution
A plasma substrate processing apparatus with a compensation plate having varying thicknesses and dielectric constants, coupled to the upper electrode, and a ground ring or cavity to control the electric field strength and plasma distribution, along with a remote plasma generator to independently generate active species, reducing the need for high-frequency RF power and minimizing contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-frequency RF power is increased to increase plasma density, then plasma density is improved, but active species are over-decomposed and etching selectivity is reduced
Solution Approach 1:
The lower surface of the upper electrode is designed with different heights at different locations (central region vs. edge region), creating local variations in the electric field strength. This allows different regions of the plasma to have different characteristics, enabling high overall plasma density while preventing over-decomposition of active species in specific areas, thus maintaining etching selectivity.
2Productivity
If RF frequency is increased to obtain high plasma density and high etching rate, then plasma density and etching rate are improved, but standing wave effect and edge effect reduce plasma uniformity
Solution Approach 1:
The upper electrode incorporates a central region with a first height and an edge region with a second height different from the first height. This local variation in electrode geometry compensates for the non-uniform electric field distribution caused by standing wave effects, creating a more uniform plasma density across the substrate surface while maintaining high etching rates.
3Manufacturing precision
If a step is provided on the electrode to spatially change electric field strength, then plasma density distribution is improved, but fluid flow is disturbed and contamination occurs
Solution Approach 1:
Instead of using sharp steps that disturb fluid flow, the invention uses gradual height variations on the lower surface of the upper electrode. The central region and edge region have different heights that create the desired electric field distribution without causing severe fluid flow disturbances, thereby reducing contamination from foreign objects.
4Quantity of substance
If conventional dual chamber structure with diffusion plate is used to generate plasma, then plasma generation is achieved, but non-uniform plasma distribution and pressure control limitations occur
Solution Approach 1:
The upper electrode's lower surface is designed with a central region at a first height and an edge region at a second height, creating local variations in electric field strength. This enables uniform plasma density distribution across the chamber while maintaining independent pressure control, overcoming the limitations of conventional diffusion plate 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
The apparatus achieves spatial control of plasma density, suppressing standing wave effects and providing uniform plasma processes, reducing contamination and maintaining high etching selectivity while minimizing the risk of electrostatic chuck damage.
Implementation Method 1
a compensation plate (166) coupled to a lower portion of the upper electrode conductive plate (165) to have different thicknesses depending on location to compensate for a height difference depending on location and having a dielectric constant
Implementation Method 2
capacitively-coupled plasma apparatus having improved plasma spatial uniformity, and more particularly, to a plasma substrate apparatus for treating a substrate by generating capacitively-coupled plasma
Implementation Method 3
plasma treatment devices are used for etching, cleaning, surface treatment, or the like. For example, plasma etching treatment devices require independent control of active species density, plasma density, and ion energy to obtain high etching selectivity and etching rate
Data Source
AI summary
A plasma substrate processing apparatus according to one embodiment of the present invention comprises: a process chamber; an upper electrode disposed in the process chamber; a substrate holder disposed under the upper electrode and facing the upper electrode to support a substrate; and an RF power source for applying RF power to the substrate holder. The upper electrode includes: an upper electrode conductive plate having lower surfaces with different heights from the substrate holder according to positions thereof; and a compensating plate coupled to a lower portion of the conductive plate, having a different thickness according to positions thereof to compensate for a height difference according to the positions of the upper electrode conductive plate, and having a dielectric constant. The lower surface of the compensating plate is coplanar.