In situ diagnostic of etch plasmas for process control using quantum cascade laser absorption spectroscopy

Lang, N.; Röpcke, J.; Wege, S.; Steinbach, Annina M.

doi:10.1051/epjap/2009198

Cited by 25 publications

(28 citation statements)

References 4 publications

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“…The origin of the artefacts using short pulses (inter pulse mode) was identified as partly of the same nature as in the case of long laser pulses (intra pulse mode). Quantitative results for CH 4 absorption features fell short of the expected values. The nominal mixing ratio (=1) was confirmed by using TDLAS.…”

Section: General Spectroscopic Issuescontrasting

confidence: 67%

“…In pure CF 4 plasmas, SiCOH layers have been etched for different power values. The correlation of online and in situ measured concentrations of two etching products, CO and SiF 4 , with the etching rates determined ex situ has been studied using quantum cascade laser absorption spectroscopy in the mid infrared spectral range.…”

Section: Industrial Process Monitoring In Low-pressure Plasmasmentioning

confidence: 99%

“…Furthermore, the applied QCLAS led to deeper insights into the chemical processes of this industrial utilized technology. The used QCL spectrometer allowed the detection of the precursor, CH 4 , and of the reaction products NH 3 , HCN and C 2 H 2 , while the latter had been detected the first time in situ in plasma nitrocarburizing processes due to the improved sensitivity realized with the multi-pass optics in PLANIMOR. The dependencies of the concentration of the carbon containing precursor and of the reaction products on the power of the screen plasma are shown in Figure 32.…”

Section: Investigations Of Plasma Nitriding and Nitrocarburizing Procmentioning

confidence: 99%

“…In the last few years, a new approach for the deposition of large area NCD films at relatively low substrate temperatures below 400˝C has been developed. A 4ˆ4 distributed antenna array (DAA) microwave plasma reactor has successfully been employed to deposit uniform NCD films on a 4-inches wafer at substrate temperatures below 300˝C using H 2 with admixtures of few per cent of CH 4 and CO 2 as feed gas. The admixture of even a low amount of CO 2 provides additional etching species and reduces the activation energy needed for diamond growth, which allows the deposition of NCD films at very low substrate temperatures [66].…”

Section: Study Of Low Pressure Low Temperature H2-ch4-co2 Microwave mentioning

confidence: 99%

“…Over the last two decades, chemical sensing using mid infrared laser absorption spectroscopy (MIR-LAS) in the molecular fingerprint region from 3 to 20 µm, which contains strong ro-vibrational absorption bands of a large variety of gaseous species, has been established as a powerful in situ diagnostic tool for molecular plasmas [1][2][3][4][5][6]. Quantum cascade lasers (QCL) in particular have played a central role in this field so much so that they have become the infrared light sources of choice for plasma diagnostics in the mid infrared.…”

Section: Introductionmentioning

confidence: 99%

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Applying Quantum Cascade Laser Spectroscopy in Plasma Diagnostics

et al. 2016

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Abstract:The considerably higher power and wider frequency coverage available from quantum cascade lasers (QCLs) in comparison to lead salt diode lasers has led to substantial advances when QCLs are used in pure and applied infrared spectroscopy. Furthermore, they can be used in both pulsed and continuous wave (cw) operation, opening up new possibilities in quantitative time resolved applications in plasmas both in the laboratory and in industry as shown in this article. However, in order to determine absolute concentrations accurately using pulsed QCLs, careful attention has to be paid to features like power saturation phenomena. Hence, we begin with a discussion of the non-linear effects which must be considered when using short or long pulse mode operation. More recently, cw QCLs have been introduced which have the advantage of higher power, better spectral resolution and lower fluctuations in light intensity compared to pulsed devices. They have proved particularly useful in sensing applications in plasmas when very low concentrations have to be monitored. Finally, the use of cw external cavity QCLs (EC-QCLs) for multi species detection is described, using a diagnostics study of a methane/nitrogen plasma as an example. The wide frequency coverage of this type of QCL laser, which is significantly broader than from a distributed feedback QCL (DFB-QCL), is a substantial advantage for multi species detection. Therefore, cw EC-QCLs are state of the art devices and have enormous potential for future plasma diagnostic studies.

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Section: General Spectroscopic Issuescontrasting

confidence: 67%

Section: Industrial Process Monitoring In Low-pressure Plasmasmentioning

confidence: 99%

Section: Investigations Of Plasma Nitriding and Nitrocarburizing Procmentioning

confidence: 99%

Section: Study Of Low Pressure Low Temperature H2-ch4-co2 Microwave mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Applying Quantum Cascade Laser Spectroscopy in Plasma Diagnostics

et al. 2016

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Oxidation of NO Into NO₂ by Surface Adsorbed O Atoms

Guaitella

Hübner

Marinov

et al. 2011

Contrib. Plasma Phys.

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Plasma-surface interactions are increasingly recognised as a key factor in explaining molecule production and conversion processes. In order to scrutinise such effects well-defined surface and gas phase conditions are required. Hence, the inner surface of a Pyrex tube was treated by a capacitively coupled RF plasma at low pressure. The post-plasma oxidation of gas mixtures containing 1 % NO into NO2 has been studied by means of quantum cascade laser absorption spectroscopy in the mid-infrared spectral range. The plasma pre-treatment experiments with oxygen containing precursors suggest O atom adsorption on the Pyrex tube with a surface density of 2.7x10 14 cm −2 . A simple kinetic model was developed and shows good agreement with the measured NO and NO2 gas phase concentrations. In the model a fraction of the surface is considered to be covered with chemisorption sites where atoms and molecules can be adsorbed, whereas they can be removed only by recombination.

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In Situ Monitoring Capabiities of Quantum Cascade Laser Absorption Spectroscopy in Industrial Plasma Processes

Lang

Macherius

Glitsch

et al. 2015

Contrib. Plasma Phys.

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Plasmas in interaction with surfaces are of key importance in a wide range of applications, which include materials technology, microelectronics, environmental issues, and biomedicine. The intense use of plasma technological processes demands proper plasma diagnostic techniques for monitoring, controlling and optimization purposes in industrial environments. In particular, for the improvement of the efficiency of a production process, in situ diagnostic techniques with online capabilities are favorable. From the middle of the last decade a variety of phenomena in molecular non-equilibrium plasmas in which many short-lived and stable species are produced have been successfully studied with quantum cascade laser absorption spectroscopy (QCLAS) in the mid-infrared spectral range. It has been possible to determine absolute concentrations of species, temperatures, degrees of dissociation, dynamics of reaction processes and phenomena involving plasma-surface interactions using spectroscopy, thereby providing a link with chemical and kinetic modelling of the plasma. Since quantum cascade lasers (QCLs) emit near room temperature, i.e., without the need of cryogenic cooling, very compact and robust spectroscopic instruments can be designed. This has stimulated the adaptation of infrared spectroscopic techniques to industrial requirements. Recent applications of infrared absorption spectroscopy using QCLs for in situ monitoring of plasma processes in industrial environments are reviewed. Examples which emphasize the capabilities of QCLAS as plasma diagnostic technique in industrial plasma processes will be given.

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In situ diagnostic of etch plasmas for process control using quantum cascade laser absorption spectroscopy

Cited by 25 publications

References 4 publications

Applying Quantum Cascade Laser Spectroscopy in Plasma Diagnostics

Applying Quantum Cascade Laser Spectroscopy in Plasma Diagnostics

Oxidation of NO Into NO₂ by Surface Adsorbed O Atoms

In Situ Monitoring Capabiities of Quantum Cascade Laser Absorption Spectroscopy in Industrial Plasma Processes

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In situ diagnostic of etch plasmas for process control using quantum cascade laser absorption spectroscopy

Cited by 25 publications

References 4 publications

Applying Quantum Cascade Laser Spectroscopy in Plasma Diagnostics

Applying Quantum Cascade Laser Spectroscopy in Plasma Diagnostics

Oxidation of NO Into NO2 by Surface Adsorbed O Atoms

In Situ Monitoring Capabiities of Quantum Cascade Laser Absorption Spectroscopy in Industrial Plasma Processes

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Product

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Oxidation of NO Into NO₂ by Surface Adsorbed O Atoms