Wavelength-Selective Filter for Rapid Thermal Processing Temperature Control
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Solution Overview
Problem
Current rapid thermal processing (RTP) systems face challenges in achieving precise temperature control and efficient cooling of semiconductor substrates, particularly due to interference from radiation pyrometry and inefficient heat management, which affects the quality and performance of substrate processing.
Innovation Solution
The implementation of a filter, such as a reflective or absorptive window, is used to block specific wavelength ranges of radiation between the heat source and the substrate, preventing unwanted radiation from reaching the substrate during heating and cooling, thereby improving temperature control and cooling rates. This filter is designed based on the substrate's absorbance characteristics and the heat source's emission spectrum to optimize heating and cooling profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high-intensity optical radiation is used to heat the substrate rapidly, then heating speed and temperature control are improved, but radiation interference with temperature measurement increases
Solution Approach 1:
A filter is introduced as an intermediary component between the heat source and substrate to selectively transmit heating radiation while blocking measurement interference. The filter allows radiation in the substrate's absorption band to pass through for heating, while blocking radiation at the measurement wavelength, thus resolving the contradiction between heating effectiveness and measurement accuracy.
Solution Approach 2:
The filter is designed with wavelength-selective properties, allowing different wavelengths to pass through selectively. It transmits radiation in specific absorption bands for heating while blocking radiation at the pyrometry measurement wavelength, creating local quality differentiation in the radiation spectrum to simultaneously achieve effective heating and accurate measurement.
2Productivity
If the substrate is heated to high temperatures rapidly, then processing efficiency is improved, but cooling rate becomes insufficient
Solution Approach 1:
The system employs periodic switching between heating and cooling phases. During heating, high-intensity radiation rapidly raises substrate temperature for efficient processing. During cooling, the heating source is turned off and the filter blocks residual radiation, enabling rapid temperature reduction. This periodic action resolves the contradiction between processing efficiency and cooling rate.
3Power
If radiation in all wavelength ranges is transmitted to the substrate, then heating effectiveness is improved, but temperature control precision deteriorates
Solution Approach 1:
The filter modifies the spectral parameters of transmitted radiation, selectively passing only wavelengths that correspond to the substrate's absorption bands while blocking other wavelengths. This parameter change in the radiation spectrum maintains high heating power through efficient absorption while improving temperature control precision by eliminating measurement interference.
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 solution enhances the accuracy of temperature measurement by reducing radiation interference and allows for faster cooling and more predictable heating profiles, leading to improved substrate processing outcomes in RTP systems.
Implementation Method 1
The implementation of a filter, such as a reflective or absorptive window, is used to block specific wavelength ranges of radiation between the heat source and the substrate
Implementation Method 2
The implementation of a filter, such as a reflective or absorptive window, is used to block specific wavelength ranges of radiation
Implementation Method 3
The implementation of a filter, such as a reflective or absorptive window, is used to block specific wavelength ranges of radiation
Implementation Method 4
the substrate, for example, a silicon wafer, is irradiated with high-intensity optical radiation in a RTP chamber to quickly heat the substrate
Implementation Method 5
The radiation is at least partially absorbed by the wafer and quickly heats it to a desired high temperature
Implementation Method 6
Temperature of the substrate is monitored by radiation pyrometry
Data Source
AI summary
Methods and apparatus for processing substrates and controlling the heating and cooling of substrates are described. A radiation source providing radiation in a first range of wavelengths heats the substrate within a predetermined temperature range, the substrate being absorptive of radiation in a second range of wavelengths within the first range of wavelengths and within the predetermined temperature rang. A filter prevents at least a portion of radiation within the second wavelength range from reaching the substrate.