Flash Lamp Annealing Apparatus with Chopper Control
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Solution Overview
Problem
Current heat treatment technologies lack a method to achieve annealing times between several seconds and one second on a semiconductor wafer, which is necessary for various process steps like activation, metallization, and wiring in transistor manufacturing, while also requiring rapid temperature rise and fall with flexible temperature profiles.
Innovation Solution
A heat treatment apparatus using a flash lamp with chopper control, driven by a pulse-signal generator and an insulated-gate bipolar transistor, allowing for adjustable annealing time and temperature profiles by controlling the light emission from the flash lamp, which can range from one millisecond to less than one second.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If halogen lamps are used to achieve intermediate annealing time, then output must be increased, but this requires increasing filament thickness which increases heat capacity and slows down temperature rise and fall rates
Solution Approach 1:
The invention changes the operating parameters of the halogen lamp by controlling the filament current waveform rather than increasing filament thickness. By using pulse-width modulation and variable current waveforms, the system achieves intermediate annealing times (1ms to 1s) without modifying the physical dimensions of the filament, thereby maintaining rapid temperature response characteristics while providing the required intermediate annealing duration.
2Duration of action of moving object
If laser annealers increase pulse beam duration to achieve intermediate annealing time, then throughput decreases due to impractically low processing speed
Solution Approach 1:
The invention replaces the laser beam scanning mechanism with a stationary halogen lamp illumination system. Instead of moving a laser beam across the wafer surface (which limits throughput), the system uses a halogen lamp that can illuminate the entire wafer surface simultaneously, achieving intermediate annealing times without sacrificing processing speed or throughput.
3Speed
If flash lamp annealers use extremely short light emission, then temperature rise is rapid but annealing time is too short for intermediate range applications
Solution Approach 1:
The invention makes the light emission duration dynamic and adjustable rather than fixed. By controlling the filament current waveform with pulse-width modulation and variable duty cycles, the system can dynamically adjust the annealing time from extremely short (maintaining rapid temperature rise) to intermediate durations (1ms to 1s), providing flexibility for different process requirements while maintaining the ability for rapid heating when needed.
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
Enables flexible setting of annealing time and temperature profiles, improving processing efficiency by allowing rapid temperature changes and reducing the need for increased filament thickness, thus enhancing throughput and precision in semiconductor wafer processing.
Implementation Method 1
a flash lamp FL to emit light to a substrate W held by a holder (7)
Data Source
AI summary
A capacitor, a coil, a flash lamp, and a switching element such as an IGBT are connected in series. A controller outputs a pulse signal to the gate of the switching element. A waveform setter sets the waveform of the pulse signal, based on the contents of input from an input unit. With electrical charge accumulated in the capacitor, a pulse signal is output to the gate of the switching element so that the flash lamp emits light intermittently. A change in the waveform of the pulse signal applied to the switching element will change the waveform of current flowing through the flash lamp and, accordingly, the form of light emission, thereby resulting in a change in the temperature profile for a semiconductor wafer.