Electrostatic Chuck Surface Structure for Stronger Wafer Fixation
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Solution Overview
Problem
Existing electrostatic chucks used in semiconductor manufacturing face challenges in maintaining sufficient electrostatic attraction without increasing the contact area between the workpiece and the chuck, which can lead to particle generation and wafer lift due to coolant gas flow.
Innovation Solution
The electrostatic chuck features a mounting surface with protrusions having a flat portion and a sloped portion with a slope angle of 65 degrees or higher and 84 degrees or lower, which increases electrostatic attraction without increasing the contact area, utilizing a combination of Johnsen-Rahbek and space coulomb forces for enhanced fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the contact area between workpiece and protrusions is increased, then electrostatic attraction is improved, but particle generation increases due to rubbing
Solution Approach 1:
The invention applies local quality by creating protrusions with distinct functional zones: a flat top portion for electrostatic attraction and sloped side portions for reduced contact. This local differentiation allows the flat portion to provide strong electrostatic force while the sloped portions minimize rubbing contact area, thereby resolving the contradiction between improving electrostatic attraction and reducing particle generation.
2Object-generated harmful factors
If the contact area between workpiece and protrusions is decreased, then particle generation is reduced, but electrostatic attraction becomes insufficient
Solution Approach 1:
The protrusions are designed with local quality differentiation where the flat top portion concentrates electrostatic attraction while the sloped side portions minimize contact area. This allows the system to maintain sufficient electrostatic force through the flat portion without increasing overall contact area, thus reducing particle generation while maintaining adequate attraction force.
3Object-generated harmful factors
If the slope angle of the sloped portion is increased, then particle generation is reduced, but manufacturing precision becomes more difficult to control
Solution Approach 1:
The invention applies parameter changes by specifying a concrete slope angle range (45° to 80°) that optimizes the balance between reducing particle generation and maintaining manufacturability. This parameter optimization ensures that the sloped portions are sufficiently steep to minimize rubbing contact and particle generation, while remaining within controllable manufacturing tolerances for standard fabrication processes.
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
This design effectively increases electrostatic attraction while minimizing particle generation and wafer lift, ensuring stable fixation of workpieces during semiconductor processing without enlarging the contact area.
Implementation Method 1
an electrostatic chuck electrode which is buried inside the electrostatic chuck and to which a voltage is applied so that the workpiece disposed on the mounting surface is fixed via electrostatic attraction
Implementation Method 2
utilizing a combination of Johnsen-Rahbek and space coulomb forces for enhanced fixation
Implementation Method 3
utilizing a combination of Johnsen-Rahbek and space coulomb forces for enhanced fixation
Data Source
AI summary
An electrostatic chuck fixing a workpiece disposed on a mounting surface via electrostatic attraction with application of a voltage to an electrode buried inside the electrostatic chuck comprises: the mounting surface having an uneven structure including a plurality of protrusions two-dimensionally spaced apart with predetermined pitches and a depression that is flat between the protrusions, each of the protrusions includes: a flat portion having a flat surface being vertical in a thickness direction of the electrostatic chuck and having a uniform height; and a sloped portion around the flat portion having a height decreasing from the flat portion toward the depression, and the sloped portion has an upper surface with a slope angle of 65 degrees or higher and 84 degrees or lower in the thickness direction of the electrostatic chuck.