Broadband IR Source for Semiconductor Inspection
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Solution Overview
Problem
Current semiconductor metrology and inspection systems are inadequate for measuring or inspecting multi-micron tall structures underneath thick hardmasks that are strongly absorbing to UV and visible light, due to low sensitivity and large measurement spot sizes, which are not suitable for high-volume semiconductor manufacturing.
Innovation Solution
A high-radiance broadband infrared (IR) source system is developed using a nonlinear optical assembly to generate broadband near-infrared and short-wavelength infrared radiation, capable of penetrating hardmasks and stacked semiconductor structures, with a method involving a pump source and nonlinear optical elements to produce IR radiation for inspection and measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UV or visible light is used for inspection, then the measurement system can operate with standard optics, but the light is strongly absorbed by hardmask materials making deep structure inspection impossible
Solution Approach 1:
The patent changes the wavelength parameter of the inspection light from UV/visible range to infrared range (specifically 1.5-5.0 micrometers). This parameter change allows the light to penetrate hardmask materials that strongly absorb shorter wavelengths, enabling inspection of deep structures underneath thick hardmasks while maintaining compatibility with standard semiconductor manufacturing processes
2Reliability
If existing IR sources are used, then the light can penetrate hardmasks, but the radiance is too low resulting in large measurement spot sizes and slow inspection speeds
Solution Approach 1:
The patent dramatically increases the radiance parameter of the IR source by using a laser-pumped plasma light source that achieves temperatures of 10,000-15,000K. This parameter change enables small measurement spot sizes (suitable for patterned wafers) while maintaining high penetration capability through hardmasks, thereby achieving inspection speeds compatible with high-volume manufacturing
Solution Approach 2:
The patent uses pulsed laser pumping of the plasma source to generate high-radiance IR emission in brief pulses. This periodic action allows the plasma to reach extremely high temperatures during each pulse, generating sufficient radiance for fast inspection while the average power remains manageable for continuous operation in manufacturing environments
3Measurement precision
If measurement spot size is reduced for better resolution, then inspection accuracy improves, but the signal level drops making measurements slower
Solution Approach 1:
The patent changes the radiance parameter of the light source to extremely high values using laser-pumped plasma. This parameter change compensates for the reduced collecting area associated with small spot sizes, maintaining sufficient signal levels for fast detection while achieving the small measurement spots needed for high-resolution inspection of patterned wafers
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 system provides increased inspection and measurement capabilities with improved sensitivity and smaller measurement spots, enabling faster and more accurate inspections of deep structures within semiconductor wafers, addressing the limitations of existing IR sources in semiconductor manufacturing.
Implementation Method 1
a nonlinear optical (NLO) assembly configured to generate broadband IR radiation in response to the pump light generated by the pump source
Implementation Method 2
broadband near-infrared and short-wavelength infrared light sources suitable for use in metrology and inspection tools
Data Source
AI summary
Systems and methods for measuring or inspecting semiconductor structures using broadband infrared radiation are disclosed. The system may include an illumination source comprising a pump source configured to generate pump light and a nonlinear optical (NLO) assembly configured to generate broadband IR radiation in response to the pump light. The system may also include a detector assembly and a set of optics configured to direct the IR radiation onto a sample and direct a portion of the IR radiation reflected and/or scattered from the sample to the detector assembly.