Light Irradiation Heat Treatment for Stable Wafer Chamber Temperature
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Solution Overview
Problem
The existing flash lamp anneal process requires multiple dummy wafers for preheating the chamber structure, increasing production costs and reducing efficiency due to the need for extensive dummy running to stabilize the temperature, which leads to uneven temperature history across semiconductor wafers in a lot.
Innovation Solution
A heat treatment method that measures the temperature decrease after processing a substrate and compares it to a threshold value, deciding whether to perform dummy processing using continuous and flash lamps to preheat the chamber without a dummy wafer, or starting the next substrate processing if the temperature remains stable, and optionally using multiple dummy wafers to efficiently stabilize the chamber temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If multiple dummy wafers are used for preheating the chamber structure, then the chamber temperature can be stabilized, but the number of dummy wafers consumed increases and production efficiency decreases
Solution Approach 1:
The patent applies preliminary action by performing dummy processing using the same flash lamp and continuous lighting lamp conditions that will be used for actual substrate processing. This preheats the chamber structure and susceptor to the target temperature before real production begins, eliminating the need for multiple dummy wafers and establishing consistent temperature history for all substrates in a lot.
Solution Approach 2:
The patent uses a single dummy wafer that copies the thermal properties and dimensions of actual substrates to simulate real processing conditions. This dummy wafer is processed through the same flash lamp annealing sequence, allowing the chamber and susceptor to reach stable temperature without consuming multiple dummy wafers.
2Temperature
If multiple dummy wafers are used for preheating, then the chamber temperature can be stabilized, but production time increases and productivity decreases
Solution Approach 1:
The patent performs preliminary heating action using flash lamp and continuous lighting lamp irradiation on a single dummy wafer before actual substrate processing. This establishes stable temperature conditions in advance, eliminating the need for multiple dummy wafers and reducing total production time while maintaining temperature stability.
Solution Approach 2:
The patent maintains continuous useful action by using continuous lighting lamps to sustain chamber and susceptor temperature between flash lamp pulses during dummy processing. This continuous heating ensures temperature stability is achieved rapidly with minimal dummy wafers, maximizing productivity.
3Stability of the object's composition
If dummy processing is performed extensively, then uniform temperature history can be achieved across wafers, but the time required for dummy running increases
Solution Approach 1:
The patent performs preliminary dummy processing with flash lamp and continuous lighting lamp irradiation to establish uniform temperature history across the chamber and susceptor before actual substrate processing. By using the same processing conditions in advance, consistent temperature profiles are achieved for all substrates in a lot without requiring extended dummy running time.
Solution Approach 2:
The patent employs feedback control by monitoring chamber and susceptor temperature during dummy processing and adjusting continuous lighting lamp power to maintain target temperature. This feedback mechanism ensures uniform temperature history is achieved rapidly and consistently, minimizing the time required for dummy running.
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 ensuring uniform temperature history across semiconductor wafers.
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
irradiating a substrate with light from continuous lighting lamps to heat the substrate
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 10 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.