Electrostatic Chuck Electrode Layout for Wafer Alignment Stability
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Solution Overview
Problem
Foreign matters adhering to the adsorption surface of electrostatic chucks can become electrically charged, leading to adsorption onto both the chuck and the wafer, and causing positional misalignment issues during wafer removal.
Innovation Solution
The electrostatic chuck design includes a base body with embedded first and second electrodes, and exposed third electrodes between adjacent first and second electrodes, along with protrusions on the surface. The third electrodes are positioned offset from the protrusions, allowing for effective charge removal from foreign matters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If foreign matters adhere to the adsorption surface of the electrostatic chuck, then the electrostatic chuck can hold the wafer, but the foreign matters become electrically charged and are adsorbed onto both the electrostatic chuck and the wafer, causing positional misalignment
Solution Approach 1:
The electrostatic chuck surface is segmented into multiple regions with different electrode configurations. First electrodes are embedded in the base body while second electrodes are exposed on the surface, creating distinct functional zones that can independently control adsorption and charge removal operations.
Solution Approach 2:
Different regions of the electrostatic chuck have different electrode arrangements optimized for specific functions. The embedded first electrodes provide stable adsorption in certain areas, while exposed second electrodes in other areas enable charge removal from foreign matters, allowing local optimization of both holding stability and alignment precision.
2Reliability
If foreign matters become electrically charged on the adsorption surface, then they are adsorbed onto the electrostatic chuck and wafer, but this causes problems with subsequent wafer delivery
Solution Approach 1:
The harmful electrical charges on foreign matters are extracted and removed from the adsorption surface by applying voltage to the second electrodes. This extraction function is performed separately from the adsorption function, allowing charges to be removed without affecting the stable holding capability of the first electrodes.
Solution Approach 2:
Before wafer delivery, the second electrodes are activated to remove charges from foreign matters in advance. This preliminary charge removal prevents alignment issues during subsequent wafer delivery operations, ensuring smooth transitions between process steps.
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 enables easy removal of electrical charges from foreign matters, preventing misalignment and ensuring proper wafer handling and delivery.
Implementation Method 1
a substrate fixing device is suggested which adsorbs and holds a wafer using Coulombic force by an electrostatic chuck
Implementation Method 2
The third electrodes are provided at positions offset from the protrusions... it is possible to easily remove charges electrically charged on foreign matters
Data Source
AI summary
An electrostatic chuck includes a base body having a first surface and a second surface opposite to the first surface, a plurality of first electrodes and a plurality of second electrodes embedded in the base body, and a plurality of third electrodes exposed from the first surface and provided between the first electrodes and the second electrodes adjacent to each other in the base body. A plurality of protrusions are formed on the first surface. The third electrodes are provided at positions offset from the protrusions in a plan view perpendicular to the first surface.