Optical Substrate Heating with LED Preheating and Flash Lamp Control
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Solution Overview
Problem
Conventional optical heating devices for semiconductor substrates face issues with temperature stabilization during preheating, leading to overshooting and non-uniform thermal history, which affects the formation of impurity diffusion layers and increases processing time.
Innovation Solution
An optical heating device utilizing LED elements for preheating and a flash lamp for rapid heating, with a control system that adjusts light output and current distribution to achieve precise temperature control, allowing for immediate flash lamp activation once the target temperature is reached, thereby reducing processing time and preventing substrate warping and cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If halogen lamps are used for preheating, then the substrate temperature can be stabilized before flash lamp heating, but the light output responds slowly to power variation causing temperature overshooting and extended processing time
Solution Approach 1:
The patent changes the fundamental parameter of the light source from halogen lamp to LED, which fundamentally alters the response characteristics. LEDs provide rapid response to power variation, eliminating the slow response and overshooting problems of halogen lamps while maintaining temperature stability, thus reducing processing time
2Temperature
If halogen lamps are used for preheating, then the substrate can be heated to target temperature, but the temperature fluctuates around the target causing non-uniform thermal history
Solution Approach 1:
Changing from halogen lamp to LED light source fundamentally improves temperature control precision. LEDs maintain stable output without the fluctuation characteristics of halogen lamps, ensuring uniform thermal history across the substrate during preheating, which directly addresses the manufacturing precision requirement
3Productivity
If the substrate is rapidly heated or cooled, then processing time is reduced, but the substrate expands and contracts causing warping and cracking
Solution Approach 1:
The patent applies preliminary preheating action using LED elements before the main flash lamp heating. This gradual preheating prepares the substrate by uniformly raising its temperature, reducing the thermal shock when flash lamps are activated, thus preventing warping and cracking while enabling rapid subsequent heating
Solution Approach 2:
The patent implements feedback control by monitoring substrate temperature and adjusting LED power accordingly. The control section receives temperature information and regulates LED output to maintain optimal heating rates, preventing excessive thermal gradients that would cause substrate deformation while maximizing heating efficiency
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
The solution enables faster and more uniform heating treatments, reducing processing time by several seconds to tens of seconds and minimizing thermal history variations, resulting in consistent semiconductor substrate characteristics.
Implementation Method 1
a plurality of LED elements for emitting light toward the substrate supported by the support member
Implementation Method 2
a flash lamp for emitting light toward the substrate supported by the support member
Implementation Method 3
the semiconductor substrate suddenly expands and contracts in accordance with the temperature variation
Data Source
AI summary
An optical heating device for heating a substrate includes:a chamber for accommodating the substrate;a pair of transmissive windows disposed on the wall of the chamber, the transmissive window facing each other for allowing light for heating to enter inside the chamber;a support member for supporting the substrate to face each of the main surfaces of the substrate and the pair of transmissive windows each other;a plurality of LED elements for emitting light toward the substrate supported by the support member;a flash lamp for emitting light toward the substrate supported by the support member; anda first lighting control unit for controlling the lighting of the flash lamp after a predetermined time has elapsed since the time of lighting the LED elements.