Wafer Preheating Light Source Layout for Uniform Edge Temperature
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Solution Overview
Problem
Current heat treatment processes for semiconductor wafers face inefficiencies due to non-uniform temperature distribution and increased costs associated with multiple power supply circuits for additional light sources during preheating, particularly in the initial stages of processing where halogen lamps require extended time to reach target temperatures and result in inefficient infrared absorption by silicon wafers at low temperatures.
Innovation Solution
A heat treatment apparatus utilizing a combination of LED lamps and VCSELs as auxiliary heating sources, where the irradiation regions overlap to ensure uniform temperature distribution across the semiconductor wafer, with a common power supply circuit to reduce size and cost, collectively controlling the outputs of both light sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If halogen lamps are used for preheating, then the semiconductor wafer can be heated, but the lamps require extended time to reach target temperatures and result in inefficient infrared absorption by silicon wafers at low temperatures
Solution Approach 1:
The patent changes the wavelength parameter of the light source from infrared (halogen lamps) to visible light (LED lamps). Silicon wafers have high absorptance for visible light even at low temperatures, whereas they have low absorptance for infrared light. This parameter change enables efficient heating from the initial stage without requiring extended warm-up time.
2Stability of the object's composition
If additional light sources are provided for uniform temperature distribution, then in-plane temperature uniformity is improved, but multiple power supply circuits are required resulting in increases in size and costs
Solution Approach 1:
The patent merges multiple light sources (LED lamps and VCSELs) into a unified system controlled by a single power supply circuit. The irradiation regions of both light sources overlap to collectively irradiate the semiconductor wafer, achieving uniform temperature distribution while avoiding the need for multiple separate power supply circuits.
Solution Approach 2:
The single power supply circuit is designed to universally control both LED lamps and VCSELs, enabling one circuit to perform the function that would otherwise require multiple dedicated circuits. This multi-functional approach reduces device complexity while maintaining temperature uniformity.
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 apparatus achieves efficient and uniform in-plane temperature distribution by overlapping the irradiation regions of LED and VCSEL light sources, reducing the need for multiple power supply circuits and enhancing the yield of non-defective chips by maintaining consistent heating across the semiconductor wafer.
Implementation Method 1
The LED lamps mainly emit visible light. Thus, even a semiconductor wafer at a relatively low temperature of 500° C. or below has a high absorptance of light emitted from the LED lamps.
Implementation Method 2
A heat treatment apparatus utilizing a combination of LED lamps and VCSELs as auxiliary heating sources
Implementation Method 3
even a semiconductor wafer at a relatively low temperature of 500° C. or below has a high absorptance of light emitted from the LED lamps
Data Source
AI summary
In an auxiliary heating part for performing a preheating treatment on a semiconductor wafer, VCSELs are arranged so as to surround LED lamps arranged in a circular region. The LED lamps irradiate the entire surface of the semiconductor wafer with light, and the VCSELs which emit light of relatively high directivity irradiate a peripheral portion of the semiconductor wafer where a temperature decrease is prone to occur with the light. A common power supply circuit is provided for the LED lamps and VCSELs that irradiate the peripheral portion of the semiconductor wafer with light. Increases in size and costs of power supply circuitry are suppressed because the single power supply circuit supplies power to the two different types of light sources to collectively control the two different types of light sources.