Electrostatic Chuck Ceramic Layer for Halogen Plasma Corrosion Resistance
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Solution Overview
Problem
Existing electrostatic chucks (ESCs) face challenges in maintaining high dielectric breakdown strength and resisting corrosion from harsh gases like fluorine and chlorine during semiconductor fabrication, due to compositions that are either attacked by halogen plasma gases or have high impurity content, leading to contamination of silicon wafers.
Innovation Solution
A layer arrangement for ESCs featuring a first ceramic layer comprising at least 90 wt% alumina, titania, ZrO2, Y2O3, AlN, Si3N4, or their combinations, doped with tantalum oxide (Ta2O5) to achieve a density of 97-99% theoretical maximum, forming a liquid Ta2O5 phase that migrates to densify the layer and create a barrier against corrosive gases, while maintaining purity and mechanical integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If traditional ceramic compositions with silica, calcia and magnesia are used as liquid phase sintering aids to densify ceramics, then the ceramic achieves high density, but the composition is attacked by halogen plasma gases (fluorine and chlorine) during semiconductor fabrication processes
Solution Approach 1:
The patent changes the chemical composition parameters of the ceramic by replacing traditional silica-calia-magnesia liquid phase sintering aids with rare earth oxides (specifically 0.1-5.0 wt% Nb2O5 and 0.1-5.0 wt% Ta2O5). This compositional parameter change enables densification to 95-99% theoretical density while simultaneously providing resistance to halogen plasma gas corrosion, resolving the contradiction between achieving high density and maintaining corrosion resistance.
Solution Approach 2:
The patent creates a composite ceramic material system combining alumina base ceramic with rare earth oxide additives (Nb2O5 and Ta2O5). This composite formulation achieves synergistic effects where the rare earth oxides serve dual functions: acting as liquid phase sintering aids for densification and forming a protective barrier phase that resists corrosion from fluorine and chlorine plasma gases, thus resolving the contradiction between density and corrosion resistance.
2Volume of stationary object
If traditional ceramic compositions with silica, calcia and magnesia are used to achieve high density, then the ceramic densifies well, but the compositions have relatively high impurity content that is not suitable for high temperature processing environments
Solution Approach 1:
The patent changes the chemical composition parameters by substituting traditional silica-calia-magnesia sintering aids with rare earth oxides (Nb2O5 and Ta2O5 at 0.1-5.0 wt% each). This parameter change achieves high density (95-99% theoretical) while maintaining extremely low impurity content, as rare earth oxides do not introduce the same level of volatile impurities as traditional additives, thus resolving the contradiction between density and purity.
Solution Approach 2:
The patent uses small amounts (0.1-5.0 wt%) of rare earth oxide additives that act as temporary liquid phase sintering aids during the sintering process. These additives facilitate densification and then remain as stable, low-volatility residual phases that do not contaminate the final product, effectively serving their purpose and leaving a high-purity final ceramic structure.
3Strength
If the ceramic layer is made near fully dense to maintain high dielectric breakdown strength, then the dielectric strength is maintained, but the ceramic becomes more susceptible to attack by corrosive process gases
Solution Approach 1:
The patent creates a composite ceramic structure where rare earth oxides (Nb2O5 and Ta2O5) form a protective barrier phase within the dense alumina matrix. This composite structure achieves both high dielectric breakdown strength (through 95-99% theoretical density) and enhanced corrosion resistance (the rare earth oxide barrier resists fluorine and chlorine attack), resolving the contradiction between dielectric strength and corrosion resistance.
Solution Approach 2:
The patent changes the chemical composition parameters by incorporating rare earth oxides that modify the ceramic's interaction with corrosive gases. The specific addition of 0.1-5.0 wt% Nb2O5 and 0.1-5.0 wt% Ta2O5 creates a denser, more chemically stable structure that maintains high dielectric strength while simultaneously providing a barrier against corrosive process gases.
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 solution provides a corrosive-resistant and high-purity dielectric layer that maintains mechanical integrity in high-temperature environments, preventing impurity mitigation and ensuring cleaner processing environments, with improved dielectric breakdown strength and reduced contamination risks.
Implementation Method 1
sufficient tantalum oxide (Ta2O5) to densify the first ceramic layer to at least 97% or 98% or 98.5% or 99.0% of the theoretical maximum density
Implementation Method 2
forming a liquid Ta2O5 phase that migrates to densify the layer
Implementation Method 3
it is paramount that the composition of the ceramic layers must not get dissolved by the corrosive process gases
Implementation Method 4
protects any metallic impurities migrating from the electrode material to the device while being processed
Data Source
AI summary
A layer arrangement for an electrostatic chuck comprises a first ceramic layer; a second ceramic layer; a metallised layered disposed between the first and second ceramic layers. The first ceramic layer comprises at least 90.0 wt % alumina, titania, ZrO2, Y2O3, AlN, Si3N4, SiC, transition metal oxides or combinations thereof; and in the range of 0.1 to 10.0 wt % tantalum oxide (Ta2O5).