Optical Heating Device for Semiconductor Wafer Uniformity
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Solution Overview
Problem
Conventional heat treatment methods in semiconductor manufacturing cause damage to miniaturized semiconductor wafers due to high temperatures and result in temperature unevenness, making it difficult to accurately monitor temperature variations using existing radiation thermometers, especially for silicon wafers.
Innovation Solution
An optical heating device with solid-state light sources emitting heating light in the range of 300 nm to 1050 nm and reference light sources emitting light in the range of 1.2 μm to 6.0 μm, along with photodetectors and a controller that compares intensity values to determine power supply, allowing for temperature monitoring and uniform heating without thermometers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional heat treatment methods are used to heat semiconductor wafers at high temperatures (500-1000°C or more), then heat treatment can be performed effectively, but the heat causes damages on narrow wiring and tiny elements formed on the semiconductor wafer
Solution Approach 1:
The invention changes the temperature parameter from conventional high temperatures (500-1000°C or more) to lower temperatures (500°C or lower) to perform heat treatment on miniaturized semiconductor wafers without causing damage to narrow wiring and tiny elements. This parameter change allows effective heat treatment while avoiding thermal damage to sensitive structures.
2Measurement precision
If radiation thermometers with detection wavelength range of 1.5 μm to 4.0 μm are used to monitor temperature at 500°C or lower, then temperature monitoring is attempted, but the radiation thermometer has difficulty in accurately monitoring the temperature variation of silicon wafers due to emissivity characteristics
Solution Approach 1:
The invention changes the detection wavelength parameter from 1.5 μm to 4.0 μm to a shorter wavelength range (0.7 μm to 1.0 μm) that is more suitable for monitoring silicon wafer temperature at 500°C or lower. This parameter change overcomes the emissivity characteristics of silicon that make temperature monitoring difficult in the longer wavelength range.
3Manufacturing precision
If the entire semiconductor wafer is heated uniformly without temperature unevenness, then film quality is improved, but achieving uniform heating at lower temperatures is more challenging
Solution Approach 1:
The invention introduces feedback control by using radiation thermometers to continuously monitor the temperature distribution across the semiconductor wafer during heat treatment. The temperature information is fed back to adjust the heating process, enabling uniform temperature distribution and improved film quality even at lower temperatures.
Solution Approach 2:
The invention divides the heating process into multiple zones or segments across the semiconductor wafer surface, allowing independent temperature control and monitoring of different regions. This segmentation enables precise control of temperature uniformity across the entire wafer, ensuring consistent film quality.
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
Enables accurate temperature monitoring and uniform heat treatment of semiconductor wafers at lower temperatures, reducing damage and temperature unevenness, while reducing the need for additional thermometers and simplifying the device configuration.
Implementation Method 1
a plurality of solid-state light sources that emit heating light having a main emission wavelength in a range of 300 nm to 1050 nm toward a main surface of the workpiece
Implementation Method 2
a plurality of photodetectors that are arranged on a plane parallel to the main surface of the workpiece to correspond to the respective reference light sources, and that output signals in response to the intensity of the reference light that has been received
Implementation Method 3
a controller that executes a reference mode in which a plurality of values of the intensity of the reference light obtained by the signals output from the photodetectors are compared in order to determine power values of power that is to be supplied to each of the solid-state light sources
Data Source
AI summary
An optical heating device includes: a chamber that accommodates a workpiece; a supporter that supports the workpiece in the chamber; a plurality of solid-state light sources emitting heating light toward a main surface of the workpiece; a plurality of reference light sources that emit reference light toward the main surface of the workpiece when power of the same power value is supplied to each of the reference light sources; a plurality of photodetectors that corresponds to the respective reference light sources, and that output signals in response to the intensity of the reference light that has been received; and a controller that executes a reference mode and a heating mode, the reference light sources and the corresponding photodetectors are arranged to face each other through the workpiece, and the photodetectors are configured to receive the reference light emitted from the reference light sources and transmitted through the workpiece.