Electrostatic Chuck Electrode Composition for Low-Resistivity Sintering
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Solution Overview
Problem
The existing electrostatic chuck devices face challenges in achieving low volume resistivity for their electrodes, which is crucial for effective wafer attraction and detachment, due to difficulties in sintering electrically conductive carbides like molybdenum carbide or tantalum carbide, leading to increased crystal grain boundaries and volume resistivity.
Innovation Solution
An electrostatic chuck device with an electrode composed of a composite sintered body having a matrix phase with insulation properties and a dispersed phase of lower volume resistivity, where the dispersed phase includes aggregated portions of molybdenum, carbon, and silicon, and the matrix phase can be primarily aluminum oxide, with specific heat treatment processes to enhance sintering and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sintering temperature is increased to promote sintering of the composite sintered body, then the sintering is improved, but aluminum oxide evaporates making it difficult to obtain a good sintered body
Solution Approach 1:
Silicon carbide particles are introduced as an intermediary substance that facilitates sintering at lower temperatures. The silicon carbide reacts with aluminum oxide to form a eutectic mixture that sinteres at lower temperatures, enabling the formation of a dense sintered body without requiring high temperatures that would cause aluminum oxide evaporation
Solution Approach 2:
The invention changes the chemical composition parameters of the composite sintered body by adding silicon carbide particles. This compositional change enables sintering at lower temperatures (below the evaporation point of aluminum oxide) while still achieving adequate sintering density and mechanical properties
2Reliability
If the abundance ratio of aluminum oxide is increased to promote sintering, then the sintering is improved, but the abundance ratio of carbide having electrical conductivity is relatively lowered, causing volume resistivity to increase
Solution Approach 1:
The invention creates a composite sintered body containing three distinct phases: aluminum oxide matrix phase, carbide dispersed phase for electrical conductivity, and silicon carbide particles that facilitate low-temperature sintering. This composite structure allows each component to fulfill its specific function without compromising the others
Solution Approach 2:
The invention applies local quality by creating distinct regions with different functions: the aluminum oxide matrix provides structural integrity and sintering promotion, the carbide dispersed phase provides electrical conductivity, and the silicon carbide particles enable low-temperature sintering. Each phase is optimally distributed to achieve its specific function
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 results in an electrostatic chuck device with a low volume resistivity electrode, enabling efficient wafer attraction and detachment, while avoiding the limitations of high sintering temperatures and aluminum oxide evaporation.
Implementation Method 1
The electrode for electrostatic attraction generates an electrostatic force (Coulomb's force) between itself and the wafer mounted on the mounting surface
Implementation Method 2
If sintering is insufficient in the composite sintered body that is the material for forming the electrode for electrostatic attraction, crystal grain boundaries increase, and thus a volume resistivity tends to increase
Data Source
AI summary
The electrostatic chuck device includes: a base having one main surface serving as a mounting surface on which a plate-shaped sample is mounted; and an electrode for electrostatic attraction provided on a side opposite to the mounting surface in the base or in an interior of the base, in which the electrode for electrostatic attraction is made of a composite sintered body that includes a matrix phase having insulation properties and a dispersed phase having a lower volume resistivity value than the matrix phase, in any cross section of the composite sintered body, a region of the dispersed phase, which is surrounded by the matrix phase and is independent, includes aggregated portions having a maximum Feret diameter of 30 μm or more, and one or more of the aggregated portions are present in a range of 2500 μm2 in any cross section of the sintered body.