Cryogenic Electrostatic Chuck With Invar Body for Vertical Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electrostatic chucks used in semiconductor manufacturing processes are not capable of operating effectively in cryogenic ranges, leading to substrate temperature control issues and etching profile degradation due to thermal expansion mismatches between chuck materials, resulting in breakage and inefficient substrate transfer.
Innovation Solution
A cryogenic electrostatic chuck system with a substrate holder and a body featuring a thermal conductivity adjustment channel made of metal-based materials, using a gas supply unit to adjust thermal conductivity based on pressure, ensuring temperature uniformity and stability for cryogenic processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the electrostatic chuck is operated at a cryogenic range, then the temperature control for cryogenic processes is improved, but the chuck breaks due to thermal expansion mismatch between aluminum chuck body and ceramic substrate holder
Solution Approach 1:
The patent changes the material parameter (coefficient of thermal expansion) of the chuck body from aluminum to Invar alloy, which has a CTE of 1.2×10^-6/°C. This parameter change allows the chuck body to match the thermal expansion characteristics of the ceramic substrate holder at cryogenic temperatures, preventing structural failure while maintaining cryogenic temperature control capability
Solution Approach 2:
The patent employs a composite structure where the chuck body is made of Invar alloy and the substrate holder is made of ceramic materials. This composite material approach combines the low thermal expansion properties of Invar with the electrical insulation and mechanical strength of ceramic, creating aChuck system that can withstand cryogenic temperatures without breaking
2Temperature
If a cryogenic chiller is used for temperature control, then the temperature uniformity is improved, but the substrate transfer efficiency deteriorates due to repeated heating and cooling cycles
Solution Approach 1:
The Invar alloy chuck body itself serves as the thermal management component, utilizing its inherent low thermal expansion properties to maintain temperature stability. This self-service approach eliminates the need for external cryogenic chillers, allowing substrates to remain at stable temperatures during transfer between process chambers without requiring heating or cooling cycles
Solution Approach 2:
The Invar alloy acts as an intermediary material between the ceramic substrate holder and the external environment. Its unique thermal properties mediate the thermal interactions, providing a stable thermal interface that maintains temperature uniformity during substrate transfer operations without requiring active cooling systems
3Stability of the object's composition
If the electrostatic chuck is operated at room temperature, then the chuck structure remains stable, but the etching profile degrades with bowing or clogging for high aspect ratio features
Solution Approach 1:
The patent changes the operating temperature parameter from room temperature to cryogenic range, which fundamentally alters the etching process characteristics. At cryogenic temperatures, the reduced atomic mobility and changed reaction kinetics prevent feature bowing and clogging, enabling high aspect ratio etching with vertical profiles while the Invar chuck maintains structural stability
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
Enables robust cryogenic etching and deposition processes by maintaining temperature uniformity and preventing chuck breakage, allowing for ideal vertical etch profiles even at high aspect ratios.
Implementation Method 1
a thermal conductivity adjustment channel 141 which adjusts a thermal conductivity based on a pressure formed by a thermal conductivity adjustment gas supplied by an adjustment gas supply unit 142
Implementation Method 2
a substrate holder 110 which holds a substrate 200 by an electrostatic force
Data Source
AI summary
A cryogenic electrostatic chuck system and a method for controlling the same according to a preferred embodiment of the present invention is capable of performing a cryogenic process for a substrate, such as a cryogenic etching process and a cryogenic deposition process, even in a cryogenic range, and is capable of implementing a vertical etch profile, which is ideal for feature etching, with a high aspect ratio.