Induction Heated Focus Ring for Uniform Etching Temperature
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Solution Overview
Problem
Existing substrate processing apparatuses face challenges in maintaining uniform temperature of the focus ring during etching, leading to inconsistent etching results due to varying focus ring temperatures across multiple wafers, and existing methods to improve heat transfer efficiency result in limitations on etching processes and potential for abnormal electric discharge.
Innovation Solution
A substrate processing apparatus with a focus ring that generates heat through induction heating by intersecting magnetic field lines, eliminating the need for external power supply and heat transfer efficiency improvement, and using a heat insulation/electrical insulation material to prevent back-flow of radio frequency electrical power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the focus ring is actively cooled to maintain uniform temperature changes across multiple wafers, then temperature uniformity is improved, but the focus ring temperature is maintained at a relatively low temperature which limits the kinds of etching processes that can be carried out
Solution Approach 1:
The focus ring is heated in advance before wafer processing begins. This preliminary heating ensures that the focus ring reaches the required temperature (300-400°C) before the first wafer is processed, eliminating temperature variations across multiple wafers while maintaining high temperature for diverse etching processes.
Solution Approach 2:
The heating is performed periodically between wafer batches rather than continuously during processing. The focus ring is heated to the required temperature, then allowed to maintain that temperature naturally during wafer processing, creating a periodic heating cycle that achieves both temperature uniformity and high temperature maintenance.
2Measurement precision
If a heater is provided in the focus ring to control temperature, then temperature control capability is improved, but abnormal electric discharge and back-flow of radio frequency electrical power may occur
Solution Approach 1:
The electrical heater system is replaced with an induction heating system that uses electromagnetic fields to heat the focus ring. This substitution eliminates direct electrical contact with the focus ring, preventing abnormal electric discharge and radio frequency power back-flow while maintaining precise temperature control capability.
Solution Approach 2:
An induction heating device serves as an intermediary between the power source and the focus ring. The induction device generates electromagnetic fields that indirectly heat the focus ring without requiring direct electrical connection, thus preventing electrical discharge issues while achieving temperature control.
3Stability of the object's composition
If heat transfer efficiency between the focus ring and susceptor is improved, then temperature uniformity is improved, but the focus ring temperature is maintained at a relatively low temperature which limits etching process options
Solution Approach 1:
The dependency of the focus ring on the susceptor for heat transfer is extracted and eliminated. By using induction heating, the focus ring generates its own heat independently rather than relying on heat transfer from the susceptor, allowing it to reach and maintain high temperatures (300-400°C) while still maintaining temperature uniformity across multiple wafers.
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 method allows for accurate temperature control of the focus ring without causing abnormal electric discharge or back-flow of radio frequency power, ensuring uniform etching results across multiple wafers by self-heating the focus ring, thereby expanding the range of etching processes that can be performed.
Implementation Method 1
the focus ring generates heat by itself
Implementation Method 2
causing magnetic field lines to intersect the focus ring
Implementation Method 3
using a heat insulation/electrical insulation material to prevent back-flow of radio frequency electrical power
Implementation Method 4
since the interior of the chamber is evacuated, a vacuum heat insulation layer is formed at a boundary between the focus ring and the susceptor
Data Source
AI summary
A substrate processing apparatus that can accurately control the temperature of a focus ring without causing abnormal electric discharge and the back-flow of radio frequency electrical power during the application of radio frequency electrical power. A wafer is mounted on a mounting stage disposed in a housing chamber. An annular focus ring is mounted on the mounting stage in such a manner as to surround the peripheral portion of the mounted wafer. The pressure in the housing chamber is reduced, radio frequency electrical power is applied to the mounting stage, and the focus ring generates heat by itself.