Semiconductor Inspection Optics for Saturation-Free High-Frequency Detection
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Solution Overview
Problem
Existing inspection apparatuses struggle to accurately detect minute jitter in semiconductor devices, particularly at high frequencies, due to limitations in light amplification and detection capabilities.
Innovation Solution
The inspection apparatus incorporates an optical amplifier to amplify input light without causing saturation, allowing for accurate detection of high-frequency phenomena using a photodetector without a multiplication layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a photodetector with a multiplication layer is used to amplify returned light, then detection accuracy is improved, but the device capacity increases and high frequency band detection becomes difficult
Solution Approach 1:
The invention separates the amplification function from the detection function. The optical amplifier (separate device) performs light amplification before the photodetector, allowing the photodetector to remain simple without a multiplication layer while still achieving high detection accuracy through the preliminary amplification of the optical signal.
2Measurement precision
If an optical amplifier is used to amplify input light, then detection accuracy of minute signals is improved, but saturation may occur causing signal loss
Solution Approach 1:
The invention dynamically adjusts the amplification conditions by controlling the pump light intensity to the optical amplifier. The pump light intensity is regulated to provide sufficient amplification for minute signals while preventing saturation that would cause signal loss, thus maintaining both detection accuracy and signal integrity.
3Object-affected harmful factors
If the light amount irradiating the semiconductor device is reduced to avoid destruction, then device safety is improved, but returned light amount decreases degrading detection accuracy
Solution Approach 1:
The optical amplifier acts as an intermediary that compensates for the reduced returned light amount. By placing the optical amplifier in the detection path, the system can use lower irradiation light levels to protect the semiconductor device while the optical amplifier amplifies the weakened returned signal to maintain detection accuracy.
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 configuration enables accurate detection of minute phenomena in a wide band, including high frequency bands, by ensuring linear amplification and avoiding signal loss due to saturation.
Implementation Method 1
an optical amplifier configured to amplify input light and output the amplified light
Implementation Method 2
a photodetector configured to detect the light output from the optical amplifier
Data Source
AI summary
An inspection apparatus includes a light source that emits light, an optical amplifier that amplifies input light and outputs the amplified light, an optical system (an objective lens, an imaging optical system, and a scanning optical system) that irradiates a semiconductor device with the light from the light source and guides light from the semiconductor device to the optical amplifier, and a photodetector that detects the light output from the optical amplifier, and the optical amplifier amplifies the input light so that saturation does not occur.