Electrostatic Chuck Anisotropic Heat Conductor Temperature Uniformity
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Solution Overview
Problem
Conventional electrostatic chucks used in semiconductor manufacturing experience temperature unevenness due to uneven heater electrode thickness or width, leading to variations in processing quality and reduced yield during plasma etching.
Innovation Solution
An electrostatic chuck design incorporating an anisotropic heat conductor with varying thermal conductivity between the attraction substrate and heater member, along with fused metal layers and adhesive layers, to facilitate even heat transfer and reduce temperature unevenness across the substrate surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a heater electrode is formed by screen printing with heat generating material paste, then the heater can be easily manufactured, but the thickness or width of the heater electrode becomes uneven, causing temperature unevenness on the attraction surface
Solution Approach 1:
An anisotropic heat conductor layer is introduced between the heater electrode and the attraction surface to act as an intermediary. This layer has higher thermal conductivity in the plane direction than in the thickness direction, which redistributes heat laterally to compensate for local variations in heater electrode thickness or width, thereby reducing temperature unevenness on the attraction surface while preserving the ease of screen printing manufacturing method
Solution Approach 2:
The thermal conductivity parameters of the heat conductor are changed by using an anisotropic material with different thermal conductivity values in different directions. The material is designed to have higher thermal conductivity in the plane direction (parallel to the attraction surface) than in the thickness direction, enabling lateral heat redistribution to compensate for heater electrode non-uniformities
2Stability of the object's composition
If a stress reducing layer is provided between the ceramic insulating plate and the metal base, then warpage due to thermal stress is reduced, but the device structure becomes more complex
Solution Approach 1:
The anisotropic heat conductor layer serves multiple functions simultaneously: it acts as a stress reducing layer to prevent warpage due to thermal expansion differences between ceramic and metal, while also functioning as a thermal management layer to redistribute heat and reduce temperature unevenness. This multi-functionality reduces the need for separate stress reducing layers, thereby limiting the increase in device complexity
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 effectively reduces temperature unevenness on the substrate, improving processing consistency and yield by ensuring uniform temperature distribution across the semiconductor wafer during plasma etching.
Implementation Method 1
The anisotropic heat conductor has an upper surface and a lower surface. The coefficient of thermal conductivity of the anisotropic heat conductor varies depending on directions. The anisotropic heat conductor is disposed between the attraction substrate and the heater member so that the coefficient of thermal conductivity in a plane direction is larger than the coefficient of thermal conductivity in a thickness direction.
Implementation Method 2
an electrostatic attraction force generated when a voltage is applied to an attraction electrode
Data Source
AI summary
An electrostatic chuck includes an anisotropic heat conductor which is disposed between an attraction substrate and a first heater member, and has an upper surface and a lower surface, and a coefficient of thermal conductivity which varies depending on directions. The anisotropic heat conductor is disposed so that the coefficient of thermal conductivity in a plane direction is larger than the coefficient of thermal conductivity in a thickness direction. Further, the electrostatic chuck includes metal layers which are joined to the anisotropic heat conductor so as to cover the upper surface and the lower surface of the anisotropic heat conductor, and an adhesive layer which is provided on a surface of each metal layer, and joins the metal layer to the attraction substrate or the heater member. Moreover, at least one of the metal layers is a fused metal layer formed by solidifying a melted metal.