Focus Ring Temperature Control via Shielded Heat Conduction
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Solution Overview
Problem
Existing plasma processing apparatuses face challenges in maintaining uniform temperature of the focus ring, which affects plasma uniformity and critical dimension deposition, especially during high aspect ratio etching processes, due to inadequate heat transfer and interference from direct heating methods.
Innovation Solution
A temperature adjusting apparatus with a grounded shielding ring and multiple heat conducting pads made of silica-gel material, allowing for independent cooling and controllable heating, effectively transferring heat to the focus ring while preventing radio frequency interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heater is directly provided in the focus ring to adjust temperature, then temperature control capability is improved, but device complexity increases and radio frequency interference occurs
Solution Approach 1:
The patent introduces a heat conducting plate as an intermediary component between the heater and the focus ring. The heater is positioned on the heat conducting plate which is in turn in contact with the focus ring, mediating the heat transfer process. This separates the heating function from the focus ring structure, avoiding direct integration of heating wires in the focus ring and thus reducing complexity and RF interference issues.
2Temperature
If a heater is directly provided in the focus ring to adjust temperature, then temperature control capability is improved, but radio frequency interference occurs
Solution Approach 1:
The heat conducting plate serves as a thermal intermediary that decouples the heater from the focus ring. This separation prevents the heater and its associated wiring from being in direct contact with the RF field environment of the focus ring, thereby eliminating the source of RF interference while maintaining effective heat transfer through the plate.
3Temperature
If cooling system is provided in the base to maintain substrate temperature, then substrate temperature uniformity is improved, but focus ring temperature control capability remains insufficient
Solution Approach 1:
The patent segments the temperature control system into two independent parts: the base cooling system for substrate temperature control, and the heater on the heat conducting plate for focus ring temperature control. This segmentation allows each component to independently control its respective temperature without interfering with the other, providing versatile temperature adjustment capability for both substrate and focus ring.
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 solution enables precise temperature control of the focus ring, enhancing plasma processing uniformity and reducing temperature-related errors, thus improving the overall etching technique by providing a robust heat conduction path and avoiding radio frequency interference.
Implementation Method 1
a heat conducting pad is provided at a portion where the shielding ring and the insulating ring contact with each other, such that heat from the heater is transferred to the focus ring through the shielding ring, the heat conducting pad, and the insulating ring
Data Source
AI summary
The present invention provides a temperature adjusting apparatus for a focus ring, wherein heat radiated from the plasma onto the focus ring is transferred downward to a base through the first heat conducting pad contacting a lower surface of the focus ring, an insulating ring contacting a lower surface of the first heat conducting pad, and the second heat conducting pad contacting a lower surface of the insulating ring, so as to be cooled by a cooling system provided at the base; turning on a heater disposed in a grounded shielding ring to generate a controllable external heating source, heat from the heater being transferred to the focus ring through the shielding ring, a third heat conducting pad contacting the shielding ring, the insulating ring contacting the third heat conducting pad, and the first heat conducting pad, so as to perform controllable warming to the focus ring. By providing a good heat conduction path in conjunction with controllable heating power, the present invention achieves a fine control of the working temperature of the focus ring such that it is tunable in processing such as etching, thereby satisfying processing demands.