Diode Laser Tile Heating Source for Rapid Thermal Processing
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Solution Overview
Problem
Incandescent halogen lamps used in rapid thermal processing have limitations such as limited radiant energy density, maximum temperature, and thermal inertia, which restrict throughput and energy control, and pose challenges in monitoring substrate temperature due to uniform heating and radiation redirection.
Innovation Solution
The use of a heating source with a frame member and a plurality of diode laser tiles mounted on its inner wall, directed towards specific areas of the substrate, allowing for controlled and uniform heating, with the ability to adjust power levels and angles for precise energy delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If incandescent halogen lamps are used as radiant source, then the substrate can be heated uniformly, but the radiant energy density is limited by the packing density of the lamps
Solution Approach 1:
The patent replaces the mechanical/incandescent lamp system with a laser-based radiant source system. Laser diodes emit coherent, high-intensity radiation that can be focused and directed precisely, eliminating the need for dense packing of incandescent lamps while achieving higher radiant energy density. The laser system uses optical components rather than thermal filaments, fundamentally substituting the heating mechanism.
Solution Approach 2:
The invention changes the fundamental parameters of the radiant source by transitioning from broadband thermal radiation of incandescent lamps to monochromatic, coherent laser radiation. This parameter change enables higher energy density because laser light can be concentrated into a smaller solid angle and focused more intensely on the substrate surface, overcoming the packing density limitation of lamp arrays.
2Speed
If incandescent halogen lamps are used, then continuous heating is provided, but thermal inertia limits the rate of temperature ramp up and ramp down
Solution Approach 1:
The patent replaces the thermal mass-based heating of incandescent lamps with direct laser radiation heating. Laser diodes have minimal thermal inertia and can be switched on and off almost instantaneously, allowing rapid modulation of heating power. This enables fast temperature ramp rates because the energy is delivered directly to the substrate without heating a large thermal mass (the lamp filaments and housing).
Solution Approach 2:
The invention enables periodic or pulsed heating action through laser diode modulation. Laser diodes can be switched rapidly between on and off states or operated in pulsed modes, allowing precise control of temperature profiles with fast ramp rates. This periodic action capability overcomes the thermal inertia limitation of continuous incandescent heating.
3Use of energy by moving object
If incandescent lamps radiant in all directions, then omnidirectional heating is achieved, but it is difficult to control the amount of energy directed towards the substrate
Solution Approach 1:
The patent applies local quality by directing laser radiation precisely at specific locations on the substrate. Laser beams can be focused to specific spots or lines, allowing localized heating with precise energy control. The energy is concentrated where needed rather than distributed omnidirectionally, enabling independent control of energy delivery to different substrate regions.
Solution Approach 2:
The invention substitutes the isotropic radiation pattern of incandescent lamps with the highly directional nature of laser beams. Laser radiation naturally propagates in a confined direction and can be further controlled using optical components like mirrors and lenses. This directional property enables precise control of energy delivery to the substrate without the need for complex shielding or redirection mechanisms.
4Difficulty of detecting and measuring
If an array of incandescent lamps covers the entire substrate surface, then uniform heating is achieved, but it is difficult to have a clear line of sight for monitoring substrate temperature
Solution Approach 1:
The patent extracts the heating function from the monitoring path by using laser diodes positioned at the periphery or above the substrate. The laser beams can be directed at the substrate from angles that do not block the line of sight for pyrometric temperature measurement. This separation of heating and monitoring paths allows both functions to operate simultaneously without interference.
Solution Approach 2:
The invention substitutes the planar array of incandescent lamps that blocks viewing with a more flexible laser heating system. Lasers can be positioned and directed from various angles, and their narrow beam profiles allow them to heat the substrate without creating a physical barrier to optical monitoring. The energy delivery is achieved through focused beams rather than a diffuse lamp array.
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 more rapid and controlled heating, improved uniformity, and increased efficiency by allowing for independent control of each laser diode tile, reducing radiative losses, and enabling instantaneous heat up and cool down, while allowing for clear monitoring of the substrate.
Implementation Method 1
a plurality of diode laser tiles mounted on the inner wall of the frame member. Each of the plurality of diode laser tiles is directed towards a corresponding area in the processing volume
Data Source
AI summary
Embodiments of the present invention provide apparatus and methods for performing rapid thermal processing. One embodiment of the present invention provides an apparatus for processing a substrate. The apparatus includes a heating source disposed outside a chamber body and configured to provide thermal energy towards a processing volume. The substrate support defines a substrate supporting plane, and the substrate support is configured to support the substrate in the substrate supporting plane. The heating source includes a frame member having an inner wall surrounding an area large enough to encompass a surface area of the substrate, and a plurality of diode laser tiles mounted on the inner wall of the frame member. Each of the plurality of diode laser tiles is directed towards a corresponding area in the processing volume.