Bipolar Electrostatic Chuck Mesa Layout for Backside Discharge Control
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Solution Overview
Problem
Existing electrostatic chucks experience mechanical defects such as hatch marks and cracking due to high electric fields between positive and negative electrodes, which can lead to substrate backside discharging and material degradation.
Innovation Solution
The introduction of a mesa feature extending along the diameter of the electrostatic chuck's top surface, contacting a surrounding ring on opposed ends, prevents the electric field from causing defects by offsetting or aligning with the electrode gap, thereby reducing DC discharge and gas breakdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high electric field is applied between positive and negative electrodes to hold the substrate, then the substrate can be securely clamped during processing, but mechanical defects such as hatch marks and cracking occur on the top surface of the electrostatic chuck
Solution Approach 1:
A mesa structure is introduced as an intermediary element between the electrodes and the top surface. The mesa extends from the top surface toward the gap between electrodes, acting as a physical barrier that intercepts and redistributes the high electric field, preventing direct field-induced mechanical stress on the top surface while maintaining substrate clamping through the surrounding electrode structure
Solution Approach 2:
The mesa structure creates local structural differentiation on the electrostatic chuck surface. By concentrating material in specific regions (the mesa protrusions), the design locally modifies electric field distribution and stress patterns, protecting vulnerable areas from field-induced mechanical defects while preserving overall functionality
2Temperature
If gas flow passages are added to control substrate temperature, then heat transfer efficiency is improved, but the complexity of the electrostatic chuck structure increases
Solution Approach 1:
The mesa structure serves multiple functions simultaneously: it acts as an electric field barrier to prevent mechanical defects, maintains structural integrity, and works in conjunction with gas flow passages for temperature control. This multi-functionality reduces the need for separate dedicated components, thereby managing complexity while achieving temperature control
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 mesa design effectively prevents hatch marks and cracking on the electrostatic chuck's surface, maintaining structural integrity and reducing mechanical defects, while maintaining heat transfer efficiency and substrate support.
Implementation Method 1
An electrostatic chuck generally includes one or more embedded electrodes which are driven to an electrical potential to hold a substrate against the electrostatic chuck during processing
Implementation Method 2
The cooling base typically includes one or more cooling channels and aids in controlling the temperature of the substrate during processing
Implementation Method 3
The gas fills the area between the electrostatic chuck and the substrate, enhancing the heat transfer rate between the substrate and the substrate support
Data Source
AI summary
Embodiments of the present disclosure provide an electrostatic chuck including a ring surrounding a top surface of the electrostatic chuck and a mesa extending along a diameter of the top surface of the electrostatic chuck such that the mesa contacts the ring on opposed ends thereof. The mesa is a single continuous feature. The mesa contacts a bottom surface of a substrate placed over the electrostatic chuck. The electrostatic chuck includes a first electrode and a second electrode. When a voltage is applied to the electrostatic chuck, an electric field is present between the first electrode and the second electrode. The mesa prevents the electric field from creating hatch marks on the top surface of the electrostatic chuck. The mesa is vertically offset from the first electrode and the second electrode or is vertically aligned with a gap defined between the first electrode and the second electrode.