Electrostatic Chuck Porous Structure Arc Discharge Suppression
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Solution Overview
Problem
Existing electrostatic chucks face challenges in reducing arc discharge during substrate processing in devices like CVD, sputtering, and etching, where inert gases are used to control substrate temperature, due to the risk of electric discharge between the ceramic dielectric substrate and the metallic base plate.
Innovation Solution
The electrostatic chuck incorporates a ceramic dielectric substrate with a porous structure, featuring a combination of sparse and dense regions, where the current flow is directed to increase the conduction path length, thereby reducing electron acceleration and suppressing arc discharge. This design includes a first porous part in the substrate and a second porous part in the base plate, with specific pore dimensions and arrangements to enhance mechanical strength and gas flow rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a gas feed channel and through hole are provided in the base plate and ceramic dielectric substrate to feed inert gas for temperature control, then substrate temperature control is improved, but arc discharge resistance deteriorates due to the creation of discharge paths
Solution Approach 1:
The patent applies porous materials by providing porous parts in the base plate and ceramic dielectric substrate at the gas feed channel and through hole. These porous parts increase the conduction path length for electric discharge while maintaining gas flow capability, thereby improving arc discharge resistance without compromising temperature control function.
Solution Approach 2:
The patent extends the discharge path in the thickness direction by creating porous structures with extended conduction paths. This dimensional approach increases the effective path length for electric discharge without adding lateral complexity, suppressing arc discharge while maintaining the gas feed channel functionality.
2Reliability
If porous parts are provided in the gas feed channel and through hole to improve arc discharge resistance by increasing conduction path length, then arc discharge resistance is improved, but gas flow rate may deteriorate due to increased flow path resistance
Solution Approach 1:
The patent applies local quality by providing porous parts with specific pore dimensions (1-10 μm) at critical locations where arc discharge is most likely to occur, while maintaining larger dimensions in other areas. This localized approach suppresses arc discharge at critical points without significantly impeding overall gas flow rate.
Solution Approach 2:
The patent optimizes the pore dimensions of the porous parts to be within 1-10 μm, which is sufficient to increase conduction path length for arc discharge suppression while small enough to maintain gas flow capability. This parameter optimization resolves the contradiction between discharge resistance and gas flow rate.
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 porous structure effectively suppresses arc discharge while maintaining high resistance and ensuring efficient gas flow, improving the reliability and performance of the electrostatic chuck in high-power environments.
Implementation Method 1
electric discharge (arc discharge) may occur from the plasma in the device toward the metallic base plate. The gas feed channel of the base plate and the through hole of the ceramic dielectric substrate may be likely to constitute a path of discharge
Implementation Method 2
the current flow is directed to increase the conduction path length, thereby reducing electron acceleration and suppressing arc discharge
Implementation Method 3
Electric power for electrostatic suction is applied to the incorporated electrode. Thus, the electrostatic chuck sucks a substrate such as a silicon wafer by electrostatic force
Implementation Method 4
an inert gas such as helium (He) is passed between the front surface of the ceramic dielectric substrate and the back surface of the suction target substrate to control the temperature of the suction target substrate
Implementation Method 5
the temperature increase of the substrate is suppressed
Data Source
AI summary
According to one embodiment, an electrostatic chuck includes a ceramic dielectric substrate, a base plate, and first and second porous parts. The ceramic dielectric substrate includes first and second major surfaces. The second major surface is opposite to the first major surface. The base plate supports the ceramic dielectric substrate and includes a gas feed channel. The first porous part is provided in the ceramic dielectric substrate and is opposite to the gas feed channel. The second porous part is provided in the base plate and is opposite to the gas feed channel. The ceramic dielectric substrate includes a first hole part positioned between the first major surface and the first porous part. The first porous part includes a first porous region including pores and a first dense region. The second porous part includes a second porous region including pores and a second dense region.