Light-Irradiation Wafer Heat Treatment With Threshold Preheating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing flash lamp anneal process requires multiple dummy wafers for preheating the chamber structure, leading to increased costs and reduced production efficiency due to temperature inconsistencies between early and late wafers in a lot during semiconductor processing.
Innovation Solution
A heat treatment method that measures the temperature decrease after processing a substrate, calculates the difference, and compares it to a threshold value to determine if dummy processing is necessary, allowing for preheating without using dummy wafers when the temperature drop is minimal, and efficiently stabilizing the chamber temperature by irradiating the susceptor with continuous and flash lamps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If dummy wafers are used for preheating the chamber structure, then the temperature stability of the chamber is improved, but the production efficiency and cost are worsened due to consumption of multiple dummy wafers
Solution Approach 1:
The system performs preliminary measurement of the chamber temperature after substrate processing to determine whether preheating is necessary before the next substrate is loaded. This preliminary assessment allows the system to avoid unnecessary dummy wafer consumption while maintaining temperature stability when needed.
Solution Approach 2:
The system continuously monitors the chamber temperature and uses this feedback information to dynamically decide whether to perform dummy processing. The control unit compares the measured temperature with predetermined thresholds and adjusts the processing accordingly, creating a closed-loop control system that optimizes both temperature stability and production efficiency.
2Stability of the object's composition
If dummy processing is performed to stabilize chamber temperature, then temperature consistency across wafers is improved, but the processing time is worsened due to additional preheating steps
Solution Approach 1:
The system performs preliminary temperature measurement after substrate processing to assess whether the chamber temperature has dropped below the threshold. This preliminary assessment allows the system to perform dummy processing only when necessary, avoiding unnecessary time loss while maintaining temperature consistency when required.
Solution Approach 2:
The system dynamically adjusts the processing sequence based on real-time temperature conditions. When the chamber temperature is sufficient, the system proceeds directly to substrate processing; when the temperature has dropped, the system performs dummy processing. This dynamic adaptation optimizes the balance between temperature consistency and processing time.
3Temperature
If the chamber is preheated using continuous lighting lamps and flash lamps, then the temperature stability is improved, but the energy consumption is increased
Solution Approach 1:
The system uses temperature measurement feedback to determine whether preheating is necessary. The control unit compares the measured chamber temperature with predetermined thresholds and activates the continuous lighting lamps and flash lamps only when the temperature drop exceeds the threshold, thereby reducing unnecessary energy consumption while maintaining temperature stability.
Solution Approach 2:
The system changes the operational parameters of the heating lamps based on temperature conditions. The lamps are activated only when the chamber temperature drops below a predetermined threshold, and the duration and intensity of heating are adjusted based on the measured temperature decrease, optimizing energy efficiency while maintaining temperature stability.
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 method reduces the number of dummy wafers consumed and efficiently stabilizes the chamber temperature, minimizing production costs and maintaining uniform temperature history across wafers in a lot.
Implementation Method 1
a radiation spectral distribution of the xenon flash lamp ranges from an ultraviolet region to a near-infrared region, thus a wavelength of the xenon flash lamp is shorter than that of a conventional halogen lamp, and almost coincides with a basic absorption band of a silicon semiconductor wafer. Thus, when the semiconductor wafer is irradiated with a flash of light emitted from the xenon flash lamp, the temperature of the semiconductor wafer can be rapidly increased with less transmitted light.
Implementation Method 2
a step (c) of comparing the decreasing temperature calculated in the step (b) with a predetermined threshold value, wherein when the decreasing temperature is larger than the threshold value, dummy processing of preheating a structure within the chamber by light irradiation from continuous lighting lamps and flash lamps is executed
Data Source
AI summary
A preceding wafer is transported from a chamber of a heat treatment apparatus after processing on the preceding wafer is completed. A temperature within the chamber at a time when the preceding wafer is transported from the chamber is defined as a transportation temperature, and a difference between a measurement temperature within the chamber measured after the preceding wafer is transported from the chamber and the transportation temperature is calculated as a decreasing temperature. The calculated decreasing temperature and a predetermined threshold value are compared with each other. When the decreasing temperature is larger than the threshold value, dummy processing of preheating an in-chamber structure such as a susceptor by light irradiation from halogen lamps and flash lamps is executed. In contrast, when the decreasing temperature is equal to or smaller than the threshold value, the dummy processing is not executed but processing on a subsequent substrate is started.