AlN Electrostatic Chuck Flatness at High Temperature
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Solution Overview
Problem
During plasma processing of semiconductor substrates, deformation due to thermal expansion differences between layers leads to non-uniformity and material wastage, as existing electrostatic chucks fail to maintain substrate flatness at high temperatures.
Innovation Solution
An electrostatic chuck with a chuck body made of aluminum nitride, having specific volume resistivity and heat conductivity values, embedded electrodes, and a dielectric material with controlled resistivity, which maintains the substrate flat and parallel by inducing opposite charge polarity for continuous Columbic attraction, and incorporates heating elements and protection circuitry for stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If an electrostatic chuck is used to clamp the substrate, then the substrate is held flat during processing, but the substrate becomes deformed at high operating temperatures due to substrate surface stress changes
Solution Approach 1:
The patent applies parameter changes by utilizing the temperature-dependent electrical resistivity characteristics of aluminum nitride material. As temperature increases, the resistivity of AlN decreases, which enhances charge migration capability and maintains electrostatic clamping force effectiveness at high temperatures, thereby preserving substrate flatness despite thermal stress changes
Solution Approach 2:
The patent replaces mechanical clamping systems with an electrostatic field-based clamping mechanism. By applying high voltage to the electrostatic chuck, electrical charges are induced on the substrate surface, creating attractive electrostatic forces that hold the substrate flat without mechanical contact, thus avoiding deformation issues associated with mechanical clamping at high temperatures
2Temperature
If the substrate is heated to high temperatures during plasma processing, then plasma enhanced deposition processes can be performed, but thermal expansion differences among layers cause substrate bowing and non-uniformity
Solution Approach 1:
The patent applies the anti-weight principle by using electrostatic forces as a counteracting mechanism against thermal expansion-induced bowing. The electrostatic chuck generates attractive forces that oppose the tendency of the substrate to deform due to differential thermal expansion among layers, thereby maintaining substrate flatness and uniformity at high processing temperatures
3Loss of substance
If the substrate is not held flat during processing, then material wastage and contamination occur, but maintaining flatness requires sophisticated electrostatic control at high temperatures
Solution Approach 1:
The patent leverages parameter changes in the aluminum nitride material properties, specifically its resistivity-temperature relationship. The decrease in resistivity at high temperatures naturally enhances charge migration and electrostatic force generation, reducing the need for additional complex control mechanisms while maintaining substrate flatness and preventing material wastage
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 electrostatic chuck effectively maintains substrate flatness and parallelism, ensuring consistent processing conditions and reducing material wastage and contamination, while providing sufficient chucking force across a wide temperature range.
Implementation Method 1
charge migration and induced opposite charge polarity, thereby providing continuous Columbic attraction
Implementation Method 2
charge migration and induced opposite charge polarity
Implementation Method 3
heat conductivity value about 60 W/m-K and 190 W/m-K
Implementation Method 4
Plasma provides many advantages in manufacturing semiconductor devices. For example, using plasma enables a wide range of applications due to lowered processing temperature
Data Source
AI summary
Embodiments of the present disclosure provide an electrostatic chuck for maintaining a flatness of a substrate being processed in a plasma reactor at high temperatures. In one embodiment, the electrostatic chuck comprises a chuck body coupled to a support stem, the chuck body having a substrate supporting surface, and the chuck body has a volume resistivity value of about 1×107 ohm-cm to about 1×1015 ohm-cm in a temperature of about 250° C. to about 700° C., and an electrode embedded in the body, the electrode is coupled to a power supply. In one example, the chuck body is composed of an aluminum nitride material which has been observed to be able to optimize chucking performance around 600° C. or above during a deposition or etch process, or any other process that employ both high operating temperature and substrate clamping features.