Infrared Fluorescence Detection for Semiconductor Ingot Impurity Mapping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing detecting apparatuses face difficulties in accurately specifying regions with different impurity concentrations in semiconductor ingots, such as facet regions, due to high fluorescence luminance from particles, leading to increased kerf loss during wafer slicing.
Innovation Solution
A detecting apparatus that utilizes an excitation light source to emit light in a predetermined wavelength, detecting fluorescence in the infrared range using a photodetector and infrared filter, and associating coordinate sets with photon numbers to identify regions with varying impurity concentrations, allowing for precise specification of facet and non-facet regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a detecting apparatus uses a bandpass filter to detect fluorescence luminance in the visible range (395-430 nm), then it can detect fluorescence from the ingot, but it cannot accurately distinguish facet regions from particles because particles also emit high luminance fluorescence
Solution Approach 1:
The patent changes the detection parameter from visible light luminance (395-430 nm) to infrared photon count (wavelength > 750 nm). This parameter change allows differentiation between facet regions and particles because particles do not emit significant infrared fluorescence, while facet regions do. The infrared filter (transmitting >750 nm) and photodetector configured for infrared detection enable this selective measurement.
2Loss of information
If the detecting apparatus detects all fluorescence emitted from the ingot without wavelength filtering, then it captures complete fluorescence information, but it includes harmful interference from particle fluorescence that masks the facet region signals
Solution Approach 1:
The patent extracts only the useful infrared component of fluorescence (>750 nm) while excluding the harmful visible range fluorescence from particles (395-430 nm). The infrared filter selectively transmits infrared wavelengths while blocking visible light, thereby extracting the facet region signal and removing particle interference in one step.
3Reliability
If the detecting apparatus uses visible light detection to identify facet regions, then it can detect fluorescence emission, but it results in increased kerf loss due to inaccurate specification of facet regions
Solution Approach 1:
By changing the detection parameter to infrared photon count, the system achieves reliable facet region specification. The infrared filter and photodetector configuration enable accurate differentiation of facet regions from other areas based on their unique infrared fluorescence characteristics, thereby reducing kerf loss through precise positioning information.
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 easy identification of regions with different impurity concentrations, reducing kerf loss and improving the efficiency of wafer slicing by accurately mapping impurity distribution.
Implementation Method 1
an excitation light source for applying excitation light having a predetermined wavelength to a face side of the ingot held on the holding surface
Implementation Method 2
a photodetector for detecting fluorescence emitted from the ingot upon exposure to the excitation light and generating an electric signal representing a number of photons
Implementation Method 3
the electric signal represents a number of photons of only light whose wavelength is in an infrared radiation range, of the detected fluorescence
Data Source
AI summary
A detecting apparatus for use in specifying regions having different impurity concentrations in an ingot includes an ingot holding unit having a holding surface for holding the ingot thereon, an excitation light source for applying excitation light having a predetermined wavelength to a face side of the ingot held on the holding surface, and a photodetector for detecting fluorescence emitted from the ingot upon exposure to the excitation light and generating an electric signal representing a number of photons of only light whose wavelength is in an infrared radiation range, of the detected fluorescence.