Electrostatic Chuck Segmentation for Wafer Edge Cooling
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Solution Overview
Problem
The existing plasma processing apparatuses face challenges in effectively cooling the circumferential edges of wafers during etching treatments, leading to temperature inconsistencies and deteriorated etching characteristics due to insufficient heat transfer from the mounting table.
Innovation Solution
A plasma processing apparatus with an electrostatic chuck featuring a first heat transfer gas diffusion region at the center and a second heat transfer gas diffusion region at the circumferential edge, where the volume ratio of the second region to the first is controlled to be equal to or less than 0.1, and the supply pressure ratio of the second heat transfer gas unit to the first is set to enhance cooling capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the outer peripheral edge of the wafer is protruded outside the mounting table to prevent plasma damage, then the mounting table is protected from plasma damage, but the heat transfer from the mounting table to the wafer circumferential edge becomes insufficient
Solution Approach 1:
The cooling system is segmented into two independent regions: a first heat transfer gas diffusion region at the center of the electrostatic chuck and a second heat transfer gas diffusion region at the circumferential edge. This segmentation allows independent temperature control of different wafer regions, enabling effective cooling of the protruded circumferential edge while maintaining proper cooling of the central region.
Solution Approach 2:
Different heat transfer gas supply conditions are applied to different regions: the second heat transfer gas diffusion region at the circumferential edge receives heat transfer gas at a higher supply pressure ratio compared to the first region. This local quality adjustment ensures sufficient cooling at the protruded circumferential edge that is most vulnerable to temperature rise.
2Device complexity
If uniform heat transfer gas supply is used across the entire electrostatic chuck, then the system structure is simple, but the temperature control precision at different wafer regions is insufficient
Solution Approach 1:
The electrostatic chuck surface is divided into distinct heat transfer gas diffusion regions with different supply characteristics. The first region serves the central wafer area while the second region serves the circumferential edge, allowing tailored temperature control for each region to achieve overall temperature uniformity.
Solution Approach 2:
Each heat transfer gas diffusion region has optimized local supply pressure ratios to match the specific thermal requirements of its corresponding wafer region. The second region at the circumferential edge uses higher supply pressure to compensate for the reduced heat transfer area, achieving uniform temperature distribution across the entire wafer surface.
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 allows for independent temperature control of the wafer's edges and inner portions, enabling local and quick cooling or heating, thereby improving etching characteristics and preventing temperature-related issues at the circumferential edges.
Implementation Method 1
an electrostatic chuck disposed on an upper portion of the mounting table body and adsorbing the substrate thereon
Implementation Method 2
a first heat transfer gas diffusion region is formed at a center of an upper surface of the electrostatic chuck and a second heat transfer gas diffusion region is formed at a circumferential edge of the upper surface of the electrostatic chuck
Data Source
AI summary
A plasma processing apparatus including a mounting table that includes a mounting table body having a temperature adjusted to be a predetermined level, and an electrostatic chuck disposed on an upper portion of the mounting table body, joined thereto with an acrylic adhesive having a thickness of 60 μm or more, to adsorb the substrate thereon. The apparatus further including first and second heat transfer gas diffusion regions formed at a center and a circumferential edge, respectively, of an upper surface of the electrostatic chuck, and first and second heat transfer gas supply units to supply heat transfer gas to the first and second heat transfer gas diffusion regions, respectively. A volume ratio of the second heat transfer gas diffusion region to the first heat transfer gas diffusion region is equal to or less than 0.1