Fiber-Coupled Radical Detection Using PPLN Frequency Doubling
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Solution Overview
Problem
Existing radical detection systems for semiconductor processing are bulky, expensive, and dangerous, lacking compact, low-powered, and dangerous integration into semiconductor processing tools.
Innovation Solution
A fiber-coupled near-infrared laser and a periodically poled lithium niobate waveguide to double the frequency is disclosed herein, in accordance with various embodiments. In the following description, numerous specific details are set forth in order to provide a thorough understanding of embodiments. It will be apparent to one skilled in the art that embodiments may be practiced without these specific details. In other instances, well-known aspects are not described in detail in order to not unnecessarily obscure embodiments. Furthermore, it is to be understood that the various embodiments shown in the accompanying drawings are illustrative representations and are not necessarily drawn to scale.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If continuous wave dye lasers are used for radical monitoring, then radical detection capability is achieved, but the system becomes bulky and requires toxic dyes
Solution Approach 1:
The patent replaces the mechanical/optical complexity of continuous wave dye lasers with a compact diode laser system. The diode laser generates near-infrared light that is frequency-doubled through nonlinear optical conversion in a periodically poled lithium niobate waveguide, eliminating the need for bulky dye laser resonators and toxic dye materials while achieving the same radical detection capability.
Solution Approach 2:
The patent changes the operating wavelength parameter from visible range (requiring dye lasers) to near-infrared range (compatible with compact diode lasers). By utilizing frequency doubling (second harmonic generation) in the PPLN waveguide, the system converts near-infrared light at 1194 nm to visible light at 597 nm, matching the NH2 radical absorption band while maintaining compactness.
2Measurement precision
If solid-state narrow-band tunable optical parametric oscillator laser is used, then radical monitoring is achieved, but the system becomes bulky
Solution Approach 1:
The patent replaces the bulky solid-state optical parametric oscillator system with a compact diode laser combined with a PPLN waveguide. The diode laser provides the pump source, and the integrated PPLN waveguide performs the frequency doubling function, eliminating the need for large optical resonators and tunable cavity systems while maintaining narrow-band spectral characteristics.
3Measurement precision
If high power class 4 lasers are used for radical monitoring, then detection capability is achieved, but the system becomes dangerous and expensive
Solution Approach 1:
The patent uses a low-power diode laser (class 1 or 2) instead of high-power class 4 lasers. The frequency doubling process in the PPLN waveguide efficiently converts the near-infrared light to visible wavelengths, achieving sufficient intensity for radical detection without requiring dangerous high power levels. This partial action approach provides adequate detection capability while eliminating safety hazards.
Solution Approach 2:
The patent employs inexpensive diode laser technology and integrated PPLN waveguides, replacing expensive high-power laser systems. The compact solid-state components have no moving parts and require minimal maintenance, providing a cost-effective solution that eliminates the high operational costs and safety risks associated with class 4 lasers.
4Measurement precision
If existing laser solutions are used for radical monitoring, then measurement capability is achieved, but integration into semiconductor processing tools becomes difficult
Solution Approach 1:
The patent integrates the PPLN waveguide within a compact housing that contains the diode laser and optical components. The fiber-optic coupling allows the system to be nested within existing semiconductor processing tool architectures, with optical fibers routing light through chamber windows to the detection region, enabling seamless integration without major tool modifications.
Solution Approach 2:
The patent uses optical fibers as intermediaries to couple the compact laser system to the processing chamber. The fiber-optic design allows flexible routing of laser light and collected signals, enabling integration into various tool configurations without requiring direct mechanical connections or complex optical alignment within the chamber environment.
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 is compact, cost-effective, and safe, allowing integration into semiconductor processing tools, enabling multiple radical species measurement with reduced power requirements.
Implementation Method 1
a periodically poled lithium niobate (PPLN) waveguide to double the frequency
Implementation Method 2
the PPLN waveguide is configured to frequency double a beam originating from the diode laser
Implementation Method 3
a first periodically poled lithium niobate (PPLN) waveguide that is coupled to the first diode laser by a first optical fiber
Implementation Method 4
a spectral filter is coupled to the PPLN waveguide by a second optical fiber
Data Source
AI summary
Embodiments described herein relate to an apparatus that includes a chamber, and a molecular radical detector coupled to the chamber. In an embodiment, the molecular radical detector includes a diode laser, and a periodically poled lithium niobate (PPLN) waveguide coupled to the diode laser by a first optical fiber. In an embodiment, a filter is optically coupled to the PPLN waveguide by a second optical fiber, and a detector is optically coupled to the filter. In an embodiment, the PPLN waveguide is configured to frequency double a beam originating from the diode laser before the beam passes through an optical port in the chamber. In an embodiment, the detector is configured to receive the beam after the beam passes through the chamber.