Electrostatic Chuck Insulating Film for Johnsen-Rahbek Force
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electrostatic chucks fail to maintain sufficient Johnsen-Rahbek force when a conductive film is deposited on both the wafer and the ceramic plate, as they often result in the same electric potential, leading to a decrease in attracting force.
Innovation Solution
An electrostatic chuck with an embedded electrostatic electrode in a disk-like ceramic plate, featuring an insulating film with higher electric resistance than the ceramic plate in an annular region around the electrode, ensuring the wafer and ceramic plate do not share the same electric potential, even when a conductive film is deposited, thus maintaining the Johnsen-Rahbek force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive film is deposited on the wafer and ceramic plate, then the wafer can be held during deposition, but the wafer and ceramic plate reach the same electric potential causing loss of Johnsen-Rahbek force
Solution Approach 1:
The patent applies local quality by creating an annular insulating film only in the outer region of the ceramic plate, while the central region remains conductive. This localized differentiation allows the outer edge to maintain potential difference (preserving Johnsen-Rahbek force) while the inner region provides conductive path for wafer holding during deposition.
Solution Approach 2:
The insulating film acts as an intermediary element between the conductive ceramic plate and the conductive film deposited on the wafer. It prevents direct electrical contact in the outer region, maintaining potential difference while allowing the system to function as intended.
2Ease of operation
If the outer circumferential edge of the wafer is placed on the conductive film of the ceramic plate, then alignment is facilitated, but the wafer and ceramic plate have the same electric potential reducing attraction
Solution Approach 1:
The patent creates a spatial differentiation where the outer annular region has insulating properties while the inner region maintains conductive properties. This allows the wafer edge to contact the conductive film for alignment purposes while the insulating outer region prevents potential equalization, preserving the attracting force.
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 effectively continues to generate the Johnsen-Rahbek force by maintaining a potential difference between the wafer and the ceramic plate, ensuring consistent attraction and secure holding of the wafer, even during repeated deposition processes and potential misalignment.
Implementation Method 1
An electrostatic chuck that attracts and holds a wafer by Johnsen-Rahbek force is known
Implementation Method 2
an insulating film with a higher electric resistance than that of the AlN ceramic plate
Data Source
AI summary
An electrostatic chuck has a structure in which an electrostatic electrode is embedded in a disk-like ceramic plate and attracts a wafer that is placed on the ceramic plate and that has a diameter smaller than that of the ceramic plate by Johnsen-Rahbek force. The electrostatic chuck includes an insulating film that has an electric resistance larger than that of the ceramic plate in an annular region of a front surface of the ceramic plate from an outer circumferential edge of the ceramic plate to the inside of an outer circumferential edge of the wafer that is placed on the ceramic plate.