LED Substrate Processing Rapid Thermal Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current rapid thermal processing systems in the semiconductor industry face limitations in heating substrate pulse durations, with tungsten-halogen lamps offering inefficient heating due to long pulse durations and limited temperature control, while flash lamps are restricted by maximum substrate temperature and pulse duration.
Innovation Solution
The use of high-radiance light emitting diodes (LEDs) for substrate processing, allowing for selectable pulse widths from under a millisecond to over a second, higher efficiency, and the ability to produce peak optical powers greater than 500 Watts/cm², enabling more precise and rapid thermal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If tungsten-halogen lamps are used for substrate heating, then continuous illumination is provided, but the pulse duration is limited to about 1 second or more due to filament reaction time
Solution Approach 1:
The patent applies parameter changes by transitioning from thermal radiation sources (tungsten-halogen lamps) to electroluminescent sources (LEDs), fundamentally changing the operating parameters including response time, pulse duration, and spectral characteristics. LEDs enable pulse durations from microseconds to seconds, whereas tungsten-halogen lamps are limited to approximately 1 second or more due to filament thermal inertia.
2Duration of action of moving object
If flash lamps are used to achieve shorter pulse durations, then pulse duration is reduced to 100 μs to 1 ms, but the maximum substrate temperature is limited
Solution Approach 1:
The patent employs parameter changes by utilizing LEDs with optimized drive currents and pulse widths to achieve both short pulse durations and high substrate temperatures. The LED's electroluminescent mechanism allows rapid switching without the temperature limitations inherent in flash lamp systems, enabling precise control of both temporal and thermal parameters.
Solution Approach 2:
The patent utilizes periodic action through controlled LED pulsing, where repeated short-duration high-intensity pulses accumulate thermal energy in the substrate without requiring continuously high instantaneous power. This allows achieving high maximum temperatures while maintaining short effective pulse durations for precise thermal processing.
3Illumination intensity
If tungsten-halogen lamps are used, then illumination is provided, but energy efficiency is less than 5% due to black-body radiation
Solution Approach 1:
The patent applies mechanics substitution by replacing the thermal radiation mechanism (black-body radiation in tungsten-halogen lamps) with electroluminescence in LEDs. This substitution eliminates the fundamental inefficiency of converting electrical energy to thermal energy and then to light, achieving greater than 50% energy efficiency compared to less than 5% for tungsten-halogen lamps.
Solution Approach 2:
The patent changes the fundamental operating parameters from thermal equilibrium black-body radiation to non-thermal electroluminescent emission. LEDs emit light directly from electron-hole recombination in semiconductor materials, producing concentrated spectral output at specific wavelengths with minimal waste heat, thereby dramatically improving energy efficiency while maintaining high illumination intensity.
4Productivity
If the substrate is heated rapidly to reduce processing time, then throughput increases, but precise temperature control becomes more difficult
Solution Approach 1:
The patent implements feedback control by using pyrometric sensors to continuously monitor substrate temperature and dynamically adjusting LED drive parameters in real-time. This closed-loop control system maintains precise temperature control during rapid heating cycles, enabling both high throughput and manufacturing precision through adaptive modulation of LED intensity and pulse timing.
Solution Approach 2:
The patent applies dynamics through time-varying LED drive waveforms, where pulse width, amplitude, and frequency are dynamically adjusted during the heating process. This enables the system to rapidly heat the substrate when needed while providing fine-grained control during critical temperature zones, achieving both high productivity and precise temperature management through adaptive temporal modulation.
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
LEDs provide efficient and rapid substrate heating, filling the gap between flash lamp and traditional RTP systems, reducing processing time, increasing throughput, and allowing for controlled pulse durations and intensities to optimize substrate treatment.
Implementation Method 1
a plurality of light emitting diodes for illuminating a first surface of the substrate in order to modify the substrate
Implementation Method 2
light emitting diodes (LEDs) for substrate processing, allowing for selectable pulse widths
Implementation Method 3
For many substrates, like silicon substrates as commonly used in the manufacture of integrated circuits, optical absorption is higher for shorter wavelengths especially at the beginning of a heating cycle
Implementation Method 4
rapid thermal processing systems utilize a high intensity light source to rapidly heat a substrate
Data Source
AI summary
Embodiments of the present invention pertain to substrate processing equipment and methods incorporating light emitting diodes (LEDs) for thermally processing substrates. Such light sources offer a variety of advantages including higher efficiency and more rapid response times. Pulse widths are selectable down to under a millisecond but can be for long pulses up to and exceeding a second. LEDs are preferable to tungsten-halogen lamps even in circumstances that allow longer processing times, since LEDs produce light with greater than 50% efficiency and tungsten-halogen lamps operate with less than 5% efficiency.