Microwave Substrate Heating Prevents Liquid Mist Contamination
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Solution Overview
Problem
Substrate processing apparatuses face contamination issues due to processing liquids evaporating into mist when they drop on infrared heaters, leading to atmospheric contamination.
Innovation Solution
A substrate processing apparatus that uses a microwave generating unit to heat the substrate from below, preventing processing liquids from evaporating into mist by maintaining a lower temperature on the heater unit, which includes a waveguide and microwave oscillator outside the heater unit, allowing for compact design and protection of the waveguide with a protective member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an infrared heater is used to heat the substrate from below, then the substrate temperature increases to activate processing liquid and enhance processing efficiency, but the heater surface temperature becomes high causing processing liquid to evaporate into mist and contaminate the atmosphere
Solution Approach 1:
The patent replaces the infrared heater (thermal radiation heating device) with a microwave generator (electromagnetic field heating device). The microwave generator irradiates microwaves to the substrate, causing dielectric heating through molecular rotation and vibration, which heats the substrate without significantly heating the heater unit surface, thus preventing processing liquid evaporation and atmospheric contamination
Solution Approach 2:
The patent introduces a microwave-transparent window as an intermediary component. This window allows microwaves to pass through to heat the substrate while preventing direct thermal contact between the microwave heating system and the processing liquid, thereby eliminating the harmful evaporation effect
2Power
If the heater unit is positioned close to the substrate to improve heating efficiency, then heating effectiveness increases, but the risk of processing liquid contacting the hot heater surface and evaporating increases
Solution Approach 1:
The patent replaces contact-based thermal heating with non-contact microwave heating. The microwave generator positioned near the substrate delivers electromagnetic energy that penetrates the substrate and causes internal heating through dielectric loss, achieving high heating efficiency without requiring the heater surface to be hot, thus eliminating the harmful evaporation effect even when positioned close to the substrate
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
Prevents processing liquids from evaporating into mist, reducing atmospheric contamination and enabling efficient substrate processing with the formation of a gas phase layer between the liquid film and the substrate surface.
Implementation Method 1
a microwave generating unit which generates microwaves toward a lower surface of the substrate from the heater unit
Implementation Method 2
a processing liquid supply means which supplies a processing liquid toward a surface of the substrate held by the chuck member
Data Source
AI summary
A substrate processing apparatus includes a spin base on which a chuck member that holds a peripheral edge of a substrate is disposed, a motor which rotates the spin base, a heater unit which is positioned between the substrate held by the chuck member and an upper surface of the spin base, a processing liquid supply unit which supplies a processing liquid toward a surface of the substrate held by the chuck member, and a microwave generating unit which generates microwaves to a lower surface of the substrate from the heater unit. The microwave generating unit may include a microwave generating member which includes a waveguide disposed in the heater unit, microwave oscillator which is disposed outside the heater unit and a coaxial cable which connects the waveguide to the microwave oscillator.