Electrostatic Chuck Soft Protrusion for Wafer Heat Transfer
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Solution Overview
Problem
In microelectronics production, electrostatic chucks face challenges in controlling temperature uniformity and minimizing particulate contamination, which can lead to substrate deformation and manufacturing yield loss due to the abrasive nature of traditional protrusions and varying contact surface characteristics.
Innovation Solution
The use of a soft protrusion structure formed from a photo-patternable polymer with a charge control layer, which provides a non-abrasive contact surface, improved manufacturability, and compatibility with grounded surface platen designs, while promoting efficient heat transfer and reducing particle contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional protrusions are used on the electrostatic chuck surface, then contact heat conduction is improved, but particulate contamination and substrate deformation increase
Solution Approach 1:
The patent changes the material parameter of the protrusions from hard traditional materials to soft materials with durometer between 20-80 Shore A. This parameter change allows the protrusions to deform elastically under wafer clamping force, maintaining contact heat conduction while reducing particle generation through abrasion. The soft material property fundamentally alters the interaction mechanics between protrusion and wafer surface.
Solution Approach 2:
The patent employs composite material construction where the protrusions are made of soft polymer materials (such as silicone rubber or polyurethane) combined with conductive fillers or metallic coatings. This composite approach provides both the softness needed to reduce particle contamination and the thermal conductivity required for effective heat transfer from the wafer backside.
2Object-affected harmful factors
If the contact surface is made softer to reduce abrasion, then particle contamination decreases, but manufacturing precision and control of contact area become difficult
Solution Approach 1:
The patent introduces dynamic adaptability through soft protrusions that automatically adjust their contact area based on applied clamping force and surface irregularities. The protrusions deform elastically to conform to the wafer backside topology, distributing contact pressure uniformly. This dynamic behavior compensates for variations in wafer flatness and protrusion height, maintaining consistent contact without requiring precision control of initial geometric parameters.
Solution Approach 2:
The patent implements local quality by creating an array of discrete protrusions with specific geometric characteristics (height, diameter, spacing) that are optimized for local contact. Each protrusion acts as an independent contact element with controlled dimensions, allowing the system to achieve uniform overall contact pressure while maintaining simplicity in manufacturing. The local geometry of each protrusion is designed to provide adequate contact area without requiring ultra-precise fabrication tolerances.
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 soft protrusion structure ensures temperature control and uniformity, reduces substrate deformation, and minimizes particulate contamination, enhancing the manufacturing process by providing a non-abrasive contact surface and improved compatibility with grounded designs.
Implementation Method 1
the back side of a substrate, such as a semiconductor wafer, is held to the face of the electrostatic chuck by an electrostatic force
Implementation Method 2
Heat delivered to the substrate during processing can be transferred away from the substrate and to the electrostatic chuck by contact heat conduction with the protrusions
Implementation Method 3
exposing a photo-patternable polymer, on a surface of the electrostatic chuck, to light through a mask
Data Source
AI summary
In accordance with an embodiment of the invention, there is provided a soft protrusion structure for an electrostatic chuck, which offers a non-abrasive contact surface for wafers, workpieces or other substrates, while also having improved manufacturability and compatibility with grounded surface platen designs. The soft protrusion structure comprises a photo-patternable polymer.