Electrostatic Chuck Surface Topology for Heat Transfer and Attraction
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Solution Overview
Problem
Substrate processing apparatuses face reduced operating rates due to poor attraction of substrates caused by deposits and particles on the electrostatic chuck, leading to obstructed contact and helium gas leakage, which necessitates frequent maintenance.
Innovation Solution
A substrate mounting stage with a surface having specific roughness parameters (arithmetic average roughness ≥ 0.45, initial wear height ≤ 0.35, roughness curve skewness ≤ -1.5, and valley-shaped portions) that prevents deposit obstruction and maintains consistent substrate attraction, ensuring efficient heat transfer and reduced maintenance needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the surface of the electrostatic chuck is made rough to increase contact area, then heat transfer efficiency is improved, but deposit accumulation obstructs substrate attraction
Solution Approach 1:
The surface is designed with dual characteristics: rough overall topology for heat transfer, but smooth local peaks for substrate contact. This local quality differentiation allows the surface to simultaneously achieve high heat transfer efficiency through roughness while maintaining reliable substrate attraction through smooth contact points that prevent deposit accumulation.
Solution Approach 2:
The surface is pre-formed with mountain-shaped portions having smooth peaks before substrate processing begins. This preliminary structuring ensures that even as deposits accumulate during operation, the smooth peaks maintain consistent substrate contact and attraction, preventing the reliability issues that would otherwise arise from deposit obstruction.
2Reliability
If conventional grinding is used to smooth the surface, then substrate attraction is maintained, but heat transfer efficiency deteriorates due to reduced contact area
Solution Approach 1:
Instead of symmetric smoothing that would create a uniformly flat surface, the invention creates an asymmetric mountain-shaped surface profile where peaks are smooth for attraction but valleys and slopes remain rough for heat transfer. This asymmetric geometry resolves the contradiction by assigning different surface characteristics to different functional zones.
Solution Approach 2:
The surface topology transitions from a two-dimensional flat plane to a three-dimensional mountain-shaped landscape. This dimensional change allows the surface to provide both smooth peak regions for substrate contact and rough valley regions for heat transfer, simultaneously achieving both attraction reliability and thermal efficiency.
3Temperature
If the surface is made extremely rough to maximize heat transfer, then thermal contact resistance is reduced, but manufacturing precision and surface control become difficult
Solution Approach 1:
The invention specifies precise parameter ranges: arithmetic average roughness Ra of 0.3-0.7 μm and maximum height roughness Rz of 1.5-3.0 μm. These controlled parameter changes ensure sufficient roughness for heat transfer while maintaining manufacturing precision through defined tolerances, preventing both thermal resistance and surface uniformity issues.
Solution Approach 2:
Traditional mechanical grinding is replaced with thermal field processing methods that can more precisely control surface topology. This substitution enables creation of the complex mountain-shaped profile with controlled roughness parameters that would be difficult to achieve through conventional mechanical means alone.
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 solution enhances substrate attraction force and heat transfer efficiency, reducing maintenance requirements and improving the operating rate of substrate processing apparatuses by ensuring consistent contact area and uniform processing temperature.
Implementation Method 1
a thermally sprayed coating film is formed on the surface of the electrostatic chuck by thermally spraying with a ceramic such as alumina
Implementation Method 2
a DC voltage is applied to the electrode plate, the electrostatic chuck attracting the wafer thereto through a Coulomb force or a Johnsen-Rahbek force generated by the DC voltage
Implementation Method 3
a DC voltage is applied to the electrode plate, the electrostatic chuck attracting the wafer thereto through a Coulomb force or a Johnsen-Rahbek force generated by the DC voltage
Implementation Method 4
the temperature of the wafer depends on the contact area between the wafer and the surface of the electrostatic chuck. If the surface of the electrostatic chuck is rough, then there is a problem that the contact area between the wafer and the surface of the electrostatic chuck is small, and hence the thermal contact resistance of the contacting portion becomes high, and the efficiency of heat transfer from the electrostatic chuck to the wafer becomes poor.
Data Source
AI summary
A substrate mounting stage that prevents poor attraction of substrates so as to improve the operating rate of a substrate processing apparatus. The substrate mounting stage is disposed in the substrate processing apparatus and has a substrate mounting surface on which a substrate is mounted. The arithmetic average roughness (Ra) of the substrate mounting surface is not less than a first predetermined value, and the initial wear height (Rpk) of the substrate mounting surface is not more than a second predetermined value.