SiC Solid Immersion Lens for Silicon Substrate Aberration
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Solution Overview
Problem
Current semiconductor observation techniques using solid immersion lenses face limitations in achieving high resolution and clear observation, particularly when dealing with silicon substrates, as they require longer wavelengths and are prone to aberration due to refractive index differences.
Innovation Solution
A solid immersion lens unit with a contact surface for silicon substrates that transmits light in the 200 nm to 1100 nm range, combined with an optical element to correct aberrations, and a semiconductor inspection apparatus incorporating this unit for high-resolution imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If light with wavelength of 1200 nm or more is used to observe silicon substrate, then light transmission through silicon is achieved, but observation resolution is insufficient
Solution Approach 1:
A solid immersion lens made of silicon carbide (SiC) is introduced as an intermediary optical element between the objective lens and the silicon substrate. SiC has high transparency in the 200-1100 nm wavelength range, enabling it to transmit shorter wavelength light that cannot penetrate silicon, while maintaining optical coupling for high-resolution observation.
Solution Approach 2:
The patent changes the material parameter of the immersion lens from conventional materials to silicon carbide, which has fundamentally different optical transmission characteristics. This material parameter change enables the system to operate in the 200-1100 nm wavelength range, achieving both high transmission and high resolution.
2Measurement precision
If solid immersion lens is used to improve resolution, then observation resolution is improved, but aberration occurs due to refractive index difference
Solution Approach 1:
An optical element serving as an intermediary is positioned between the objective lens and the solid immersion lens to correct aberrations. This intermediary element compensates for the refractive index mismatch between the silicon substrate and the SiC immersion lens, maintaining image quality while enabling high-resolution observation.
3Measurement precision
If shorter wavelength light is used to improve resolution, then observation resolution is improved, but light transmission through silicon substrate becomes insufficient
Solution Approach 1:
The silicon carbide solid immersion lens acts as an optical intermediary that is transparent to short wavelength light (200-1100 nm) that cannot penetrate the silicon substrate. This enables the use of shorter wavelengths for high-resolution observation while maintaining adequate light transmission through the imaging path.
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 high-resolution and clear observation by using shorter wavelengths and correcting aberrations, reducing the need for additional correction components and improving observation accuracy.
Implementation Method 1
the solid immersion lens transmits light having at least a part of a wavelength in a range of 200 nm or greater and 1100 nm or lower
Implementation Method 2
the optical element corrects aberration caused by a difference in refractive indices between the silicon substrate and the solid immersion lens
Data Source
AI summary
A solid immersion lens unit includes a solid immersion lens having a contact surface for coming into contact with semiconductor device formed of a silicon substrate and a spherical surface to be disposed to face an objective lens; a holder holding the solid immersion lens; and an optical element held by the holder to be positioned between the objective lens and the solid immersion lens. The solid immersion lens transmits light having at least a part of wavelength in a range of 200 nm or greater and 1100 nm or lower. The optical element corrects aberration caused by a difference in refractive indices between the silicon substrate and the solid immersion lens.