Light-Irradiation Wafer Heating Under Negative Chamber Pressure
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Solution Overview
Problem
The existing flash lamp annealing processes face challenges in maintaining a stable pressure within the treatment chamber, leading to potential gas leaks and equipment deterioration due to repeated pressure changes.
Innovation Solution
A heat treatment apparatus and method that maintain a treatment chamber under negative pressure relative to the outside, using a controller to manage gas supply and exhaust to keep the pressure at or below a reference pressure lower than atmospheric pressure, preventing gas leaks and equipment damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pressure in the treatment chamber is repeatedly reduced and returned to atmospheric pressure for each substrate treatment, then the substrate can be treated in a controlled atmosphere, but the O-rings and sealing parts deteriorate and break in a relatively short time, causing treatment gas to leak out
Solution Approach 1:
The treatment chamber is preliminarily evacuated to a reduced pressure state before substrate treatment begins. This preliminary action allows the chamber to maintain a baseline negative pressure that prevents gas leakage and reduces stress on sealing components during the treatment process, eliminating the need for repeated pressure cycling that causes O-ring deterioration.
2Productivity
If nitrogen or other gases are supplied into the treatment chamber to return the pressure to atmospheric pressure after treatment, then the chamber is prepared for the next substrate, but pressure variations overshoot and create positive pressure that causes harmful gases to leak out
Solution Approach 1:
The pressure control system continuously monitors the pressure in the treatment chamber and provides feedback control to the gas supply and exhaust systems. This feedback mechanism prevents pressure overshooting by adjusting gas flow rates in real-time, ensuring the pressure remains at or below atmospheric pressure at all times, thereby preventing harmful gas leakage while maintaining efficient treatment cycles.
3Ease of operation
If the pressure in the treatment chamber is maintained at atmospheric pressure, then gas can be freely supplied for treatment, but there is a danger that ammonia or other harmful gases may leak out when pressure variations occur
Solution Approach 1:
The treatment chamber is maintained at a reduced pressure state, creating a controlled inert environment that prevents harmful gas leakage. This approach simplifies gas supply operations while eliminating safety risks by ensuring that the chamber pressure never exceeds atmospheric pressure, thus preventing ammonia and other harmful gases from leaking into the surrounding environment.
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 effectively prevents gas leaks by maintaining negative pressure within the treatment chamber, reducing the risk of harmful gas escape and equipment deterioration, while also improving process efficiency by maintaining consistent pressure conditions.
Implementation Method 1
The xenon flash lamps have a spectral distribution of radiation ranging from ultraviolet to near-infrared regions. The wavelength of light emitted from the xenon flash lamps is shorter than that of light emitted from conventional halogen lamps, and approximately coincides with a fundamental absorption band of a silicon semiconductor wafer. Thus, when a semiconductor wafer is irradiated with a flash of light emitted from the xenon flash lamps, the temperature of the semiconductor wafer can be raised rapidly
Implementation Method 2
the flash lamp annealing is performed in some cases while supplying a specific treatment gas (e.g., ammonia, ozone, or the like) in a reduced-pressure atmosphere in which the pressure in a treatment chamber is reduced to, for example, approximately 5 to 50 kPa
Data Source
AI summary
Heating treatment is performed by irradiating a semiconductor wafer with light in a reduced pressure atmosphere in a treatment chamber. Pressure in the treatment chamber is set to a base pressure that is a fixed value lower than atmospheric pressure when the semiconductor wafer is transported into and out of the treatment chamber. The pressure in the treatment chamber is less than the base pressure when the heating treatment is performed on the semiconductor wafer. Since the pressure in the treatment chamber is always maintained below atmospheric pressure, even if pressure variations in the treatment chamber overshoot more or less from the base pressure, the inside of the treatment chamber is always under a negative pressure relative to the outside of an apparatus. This prevents gas from leaking out of the treatment chamber.