Laser-Heated Wet Etching for Uniform Wafer Temperature
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Solution Overview
Problem
In semiconductor device manufacturing, high-temperature wet etching processes face challenges in achieving uniform temperature and etching rates due to limitations in heating the etchant, leading to uneven etching results across the wafer surface.
Innovation Solution
A wet etching apparatus that uses a laser unit to directly heat the wafer to the desired process temperature, while the etchant is circulated to maintain uniform flow and prevent contamination, ensuring consistent etching across the wafer surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the etchant is heated to high temperature, then the etching rate increases, but the temperature becomes uneven due to boiling point limitations and heat resistance constraints
Solution Approach 1:
A susceptor is introduced as an intermediary component between the microwave field and the etchant. The susceptor absorbs microwave energy and converts it to heat, then transfers this heat to the etchant through thermal conduction. This mediator approach allows achieving high temperatures without directly heating the etchant with microwaves, thereby improving temperature uniformity while maintaining high etching temperatures
Solution Approach 2:
The patent replaces conventional contact-based heating systems with microwave-based electromagnetic heating. The microwave field penetrates the etchant and heats it volumetrically through dielectric loss, eliminating the need for physical heating elements that would create temperature gradients and are limited by heat resistance materials
2Temperature
If conventional heating methods are used, then the etchant can be heated, but the maximum temperature is limited by the boiling point of the etchant
Solution Approach 1:
The patent utilizes the phase transition properties of the etchant under microwave irradiation. By controlling the microwave power and duty cycle, the system can maintain the etchant in a liquid state at temperatures approaching or exceeding the normal boiling point through rapid heating cycles, effectively expanding the usable temperature range for etching processes
Solution Approach 2:
The system changes the physical parameters of the etching process by introducing microwave irradiation as a new heating mechanism. This allows the etching temperature to be decoupled from the etchant's boiling point limitation, as the microwave energy is continuously supplied to maintain temperature despite phase change tendencies, expanding the achievable temperature range
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 approach allows for uniform heating of the wafer, achieving the desired high etching temperatures and maintaining a consistent etching rate, even in areas like the wafer edge, thereby improving the precision and reliability of the etching process.
Implementation Method 1
A laser unit is disposed above the process bath and is configured to direct a laser beam to the wafer and to heat the wafer thereby
Implementation Method 2
A circulation pump is mounted on the pipe
Data Source
AI summary
A wet etching apparatus includes a process bath having an internal space configured to receive an etchant and having a support unit, on which a wafer is disposed to be in contact with the etchant. A laser unit is disposed above the process bath and is configured to direct a laser beam to the wafer and to heat the wafer thereby. An etchant supply unit is configured to supply the etchant to the internal space of the process bath.