Electrostatic Chuck Structure to Prevent Wafer Scratches
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Solution Overview
Problem
The existing electrostatic chuck apparatuses in semiconductor manufacturing cause scratches on wafers due to excessive Johnsen-Rahbek force generated between the support base and the wafer during high-temperature processes.
Innovation Solution
An electrostatic chuck apparatus with a substrate support plate featuring protrusion-shaped support bases and internally positioned ground electrodes, which prevents the Johnsen-Rahbek force by ensuring no voltage is applied to the support bases, allowing only Coulomb force to act for chucking, thereby reducing stress on the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If support bases protrude from the substrate support plate to reduce contact area, then heat conduction is improved, but Johnsen-Rahbek force is generated causing wafer scratches
Solution Approach 1:
The substrate support plate is segmented into multiple protrusion-shaped support bases, each independently positioned. This segmentation allows heat conduction through discrete contact points while the ground electrodes are similarly segmented and positioned to prevent Johnsen-Rahbek force generation at each support base location
Solution Approach 2:
Ground electrodes are introduced as intermediary elements between the support bases and the wafer. These ground electrodes are positioned to extend toward the wafer surface and are electrically connected to the support bases, serving as mediators that prevent voltage application to the support bases and eliminate Johnsen-Rahbek force while maintaining thermal contact
2Force
If voltage is applied to the substrate support plate for electrostatic chucking, then chucking force is generated, but Johnsen-Rahbek force is generated causing local stress on the wafer
Solution Approach 1:
The harmful Johnsen-Rahbek force is extracted or eliminated from the system by introducing ground electrodes that prevent voltage application to the support bases. The electrostatic chucking function is retained through the main chucking electrode, while the ground electrodes specifically remove the problematic localized force generation at support base positions
Solution Approach 2:
Different regions of the substrate support plate are given different electrical properties. The support bases and their corresponding ground electrodes are configured to have grounded potential to eliminate local Johnsen-Rahbek force, while the main chucking electrode maintains the overall electrostatic field for chucking. This local differentiation of electrical quality prevents harmful localized stress
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
Prevents scratches on the wafer surface by eliminating the Johnsen-Rahbek force, ensuring effective chucking without local stress, and improving temperature uniformity and heat conduction.
Implementation Method 1
by chucking the wafer on the substrate support plate by electrostatic force, the warpage of the wafer caused by Coulomb force can be prevented
Implementation Method 2
the warpage of the wafer caused by Coulomb force can be prevented
Implementation Method 3
improving temperature uniformity and heat conduction
Data Source
AI summary
According to one embodiment, an electrostatic chuck apparatus includes a substrate support plate formed of a dielectric material. The substrate support plate includes: a plurality of support bases protruding from an upper surface of the substrate support plate, a plurality of ground electrodes formed inside the substrate support plate, each of the ground electrodes at a corresponding position to a respective one the support bases, and an electrostatic chuck electrode provided below the ground electrodes.