Broadband Light Source Using Nested Reflectors for Semiconductor Inspection
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Solution Overview
Problem
As semiconductor devices become more vertically integrated, internal manufacturing defects within the devices increase, requiring an optical inspecting system that can utilize a broadband light source with a wide wavelength range and high intensity to effectively inspect both surface and internal defects.
Innovation Solution
A broadband light source is developed using a laser-produced plasma (LPP) system, incorporating an electrodeless lamp, elliptical and spherical reflectors, and a laser irradiator to generate and focus broadband light efficiently, with a path changer to optimize optical paths and increase intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional light source is used, then the device complexity is low, but the illumination intensity and wavelength range are insufficient for inspecting internal defects in vertically integrated semiconductor devices
Solution Approach 1:
The light source system is segmented into multiple functional components: electrodeless lamp for broadband light generation, elliptical reflector for light collection, spherical reflector for additional light gathering, and laser irradiator for plasma generation. Each component performs a specific function to collectively achieve high illumination intensity and broadband characteristics necessary for inspecting internal defects in semiconductor devices
Solution Approach 2:
The electrodeless lamp is positioned within the elliptical reflector, which is in turn positioned within the spherical reflector. This nested arrangement allows the lamp to be centrally located while both reflectors work together to maximize light collection from multiple directions, achieving high illumination intensity without proportionally increasing overall system complexity
2Adaptability or versatility
If a conventional light source is used, then the device complexity is low, but the wavelength range is insufficient for inspecting various defects
Solution Approach 1:
The optical system is segmented into multiple specialized components, each optimized for specific wavelength manipulation. The electrodeless lamp generates broadband light covering multiple wavelength ranges, while the elliptical and spherical reflectors are designed to efficiently collect and direct specific wavelength bands, enabling versatile defect inspection across different wavelength ranges
Solution Approach 2:
The electrodeless lamp serves multiple functions by generating broadband light that covers a wide wavelength range, making the system adaptable for inspecting various types of defects including surface and internal defects. The reflector system is designed to handle multiple wavelength bands simultaneously, providing universal applicability for different inspection requirements
3Measurement precision
If light intensity is increased to reach sufficient depth within devices, then the measurement precision for internal defects improves, but the loss of energy increases
Solution Approach 1:
The system extracts and utilizes light that would otherwise be lost or underutilized. The elliptical reflector is positioned to capture light emitted from the electrodeless lamp that would otherwise travel uselessly, redirecting it toward the inspection target. The spherical reflector further extracts and redirects additional light paths, maximizing the utilization of generated light energy while achieving sufficient penetration depth for precise internal defect measurement
Solution Approach 2:
The reflector system creates a feedback mechanism where light is continuously redirected and reused. The elliptical and spherical reflectors work together to bounce light back toward the inspection target multiple times, effectively increasing the path length and penetration depth without proportionally increasing energy consumption, thereby improving measurement precision for internal defects
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 solution provides a high-intensity broadband light source capable of effectively inspecting both surface and internal defects in semiconductor devices, enhancing the detection of defects like voids and bridge defects by increasing the intensity and wavelength range of the inspection light.
Implementation Method 1
a laser irradiator to provide a laser beam to the electrodeless lamp through the path hole of the spherical reflector to generate the plasma in the electrodeless lamp
Implementation Method 2
A broadband light source is developed using a laser-produced plasma (LPP) system
Implementation Method 3
an elliptical reflector having first and second focuses, the elliptical reflector enclosing a rear portion of the electrodeless lamp positioned at the first focus of the elliptical reflector such that the broadband light is reflected from the elliptical reflector toward a light collector as a collective light
Implementation Method 4
a spherical reflector having a spherical center at which the electrodeless lamp is positioned, the spherical reflector enclosing a front portion of the electrodeless lamp such that the broadband light is reflected from the spherical reflector toward the elliptical reflector
Data Source
AI summary
A broadband light source includes a first electrodeless lamp to generate first broadband light from plasma, a first elliptical reflector having first and second focuses, the first elliptical reflector enclosing a rear portion of the first electrodeless lamp positioned at the first focus of the first elliptical reflector such that the first broadband light is reflected from the first elliptical reflector toward a light collector as a collective light, a symmetrically curved reflector having a third focus, the symmetrically curved reflector positioned such that the third focus is coincident with one of the first and second focuses, and a laser irradiator to provide a laser beam to the first electrodeless lamp.