Roughened Heating Element in Substrate Holding Apparatus
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Solution Overview
Problem
Conventional substrate holding apparatuses face issues with thermal uniformity due to variations in the thickness of screen-printed heating elements, leading to inadequate heat tolerance, as the adhesive used to bond these elements to the electrostatic chuck dissolves at elevated temperatures.
Innovation Solution
A substrate holding apparatus is designed with a heating unit that includes a heating element with a roughened surface, encapsulated in an insulating layer, which is directly bonded to the electrostatic chuck, improving heat distribution and increasing the upper temperature limit by using a rolled alloy with a lower specific resistance and a high-thermal-conductivity insulating layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a screen-printed heating element is used in the electrostatic chuck, then the heating element can be formed, but the thickness varies leading to poor thermal uniformity
Solution Approach 1:
The patent changes the formation method of the heating element from screen printing to a method that controls thickness more precisely, thereby maintaining ease of manufacture while improving thickness uniformity and thermal performance
Solution Approach 2:
The patent uses a composite structure where the heating element is embedded in an insulating layer that is directly bonded to the electrostatic chuck, creating a more uniform thermal field while maintaining manufacturing feasibility
2Ease of manufacture
If an adhesive agent is used to bond the heating element to the electrostatic chuck, then the heating element can be attached, but the adhesive dissolves at temperatures above 150 degrees Celsius
Solution Approach 1:
The patent removes the adhesive agent from the bonding process entirely, replacing it with a direct bond between the insulating layer and the electrostatic chuck, thereby eliminating the temperature limitation of the adhesive while maintaining attachment capability
Solution Approach 2:
The insulating layer serves as an intermediary between the heating element and the electrostatic chuck, providing both electrical insulation and mechanical bonding without requiring temperature-sensitive adhesive materials
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 configuration enhances thermal uniformity and increases the upper temperature limit of the substrate holding apparatus to approximately 200 degrees Celsius, overcoming the limitations of conventional systems.
Implementation Method 1
a heating element having at least one roughened surface
Implementation Method 2
the insulating layer and the electrostatic chuck are directly bonded to each other
Implementation Method 3
a substrate holding apparatus that clamps a wafer with an electrostatic chuck
Data Source
AI summary
A substrate holding apparatus includes a baseplate, a heating unit disposed over the baseplate, and an electrostatic chuck disposed on the heating unit, wherein the heating unit includes a heating element having at least one roughened surface and an insulating layer enclosing the heating element, and the insulating layer and the electrostatic chuck are directly bonded to each other.