Electrostatic Chuck With Dielectric Plate For Uniform Plasma
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Solution Overview
Problem
In plasma processing, the in-plane uniformity of the electric field strength is compromised due to uneven electron density distribution, leading to variations in processing rates across the surface of plate-like samples, particularly when using high-frequency discharge type plasma processing apparatuses.
Innovation Solution
An electrostatic chuck device is designed with a concave portion on the metal base section and a dielectric plate bonded with an insulating adhesive layer of lower dielectric constant, which prevents high-frequency current from flowing to the peripheral edges, ensuring even electric field strength and plasma density across the sample surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high-frequency power is applied to generate plasma, then plasma is generated and processing can be performed, but the electric field strength becomes uneven (higher at center, lower at periphery), causing non-uniform plasma density and processing rate variations
Solution Approach 1:
The patent introduces a dielectric layer specifically at the central portion of the lower electrode where the electric field is excessively strong. This local modification creates different electrical properties in different regions: the dielectric layer reduces the electric field strength at the center while the periphery remains unchanged, thereby achieving uniform electric field distribution and uniform plasma density across the substrate surface.
2Manufacturing precision
If a dielectric layer is buried at the central portion of the lower electrode to equalize electric field distribution, then in-plane uniformity of electric field strength is improved, but high-frequency current flows along the surface and leaks toward the lower electrode, generating hollow cylindrical resonance and weakening the electric field at the center
Solution Approach 1:
The patent introduces an electrostatic chuck section as an intermediary component between the substrate and the lower electrode. This electrostatic chuck section includes a substrate with an electrostatic-adsorption inner electrode, which serves as a mediator to prevent direct high-frequency current leakage while maintaining the beneficial electric field distribution. The electrostatic chuck section allows the high-frequency current to pass through without significant leakage, thus preventing resonance while maintaining uniform electric field strength.
3Device complexity
If the electrostatic chuck section is fixed directly to the metal base section, then structural simplicity is maintained, but warping and peeling may occur due to thermal expansion differences and processing stresses
Solution Approach 1:
The patent introduces an insulating adhesive bonding layer as a composite material interface between the electrostatic chuck section and the metal base section. This bonding layer serves multiple functions: it provides electrical insulation, accommodates thermal expansion differences between the electrostatic chuck section and the metal base section, and prevents warping and peeling during processing. The use of this composite bonding layer enhances the reliability and durability of the electrostatic chuck device while maintaining structural integrity.
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 achieves uniform plasma processing by maintaining even electric field strength and plasma density, enhancing in-plane thermal uniformity and preventing warping or peeling issues, thereby ensuring consistent processing results across the entire sample surface.
Implementation Method 1
a dielectric plate is fixed to the concave portion. The dielectric plate and the electrostatic chuck section are adhesively bonded to each other with an insulating adhesive bonding layer interposed therebetween, the dielectric constant of which is smaller than that of any one of the dielectric plate and the substrate
Implementation Method 2
an electrostatic-adsorption inner electrode 5 built therein, and a power supply terminal 6 for applying a DC voltage to the electrostatic-adsorption inner electrode 5... adsorbs the plate-like sample W, by placing the plate-like sample W on the mounting surface 4a and allowing the high DC voltage source 7 to apply a DC voltage to the electrostatic-adsorption inner electrode 5
Implementation Method 3
by allowing the high-frequency voltage generating source 8 to apply high-frequency power across the metal base section 3 (lower electrode) and an upper electrode (not shown), a high-frequency electric field is generated in the chamber. The high-frequency electric field accelerates electrons, plasma is generated due to ionization by collision of the electrons with the process gas
Data Source
AI summary
An electrostatic chuck device includes an electrostatic chuck section including a substrate and a power supply terminal for applying a DC voltage to an electrostatic-adsorption inner electrode; and a metal base section fixed to the other main surface of the electrostatic chuck section. Here, a concave portion is formed in the main surface of the metal base section facing the electrostatic chuck section and a dielectric plate is fixed to the concave portion. The dielectric plate and the electrostatic chuck section are adhesively bonded to each other with an insulating adhesive bonding layer interposed therebetween. The dielectric plate and the concave portion are adhesively bonded to each other with an insulating adhesive bonding layer interposed therebetween. The dielectric constant of the insulating adhesive bonding layer is smaller than that of any one of the dielectric plate and the substrate.