Influence of plasma composition on reflectance anisotropy spectra for in situ III–V semiconductor dry-etch monitoring

Barzen, Lars; Kleinschmidt, Ann-Kathrin; Strassner, Johannes; Doering, Christoph; Fouckhardt, Henning; Böck, Wolfgang; Wahl, Michael; Kopnarski, Michael

doi:10.1016/j.apsusc.2015.09.040

Cited by 7 publications

(14 citation statements)

References 54 publications

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“…The chlorine share should not exceed 20% though, because otherwise the RAS spectra will not be clearly characteristic of the etch front. Details on the determination of the optimum gas parameters, especially for etching GaAs and Al 0.5 Ga 0.5 As, and on the influence of the plasma gas composition on RAS can be found in [9]. …”

Section: Resultsmentioning

confidence: 99%

“…In this contribution the high accuracy in etch depth control with RAS, which until now had been estimated only in our earlier publications [8–9], is demonstrated. Different etch depths have been monitored during etching of layered samples and the results are compared to secondary ion mass spectrometry (SIMS) measurements of the remaining layer thicknesses.…”

Section: Introductionmentioning

confidence: 89%

“…In [8–9] we have investigated the applicability of the RAS method and equipment to monitor the current etch depth in situ in dry-etch processes with high accuracy and reproducibility. Dry-etching is an essential step of many lithographic processes, e.g., in semiconductor device fabrication, and offers several advantages over wet-etching as for instance the opportunity to achieve anisotropic etching and vertical etch flanks [10–11].…”

Section: Introductionmentioning

confidence: 99%

“…Due to the broad spectral range even structures with many layers of different material composition may be monitored during a single etch process. Furthermore, RAS data contain information on the sample surface (etch front) morphology [9], which are indicative of the roughness.…”

Section: Introductionmentioning

confidence: 99%

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Precise in situ etch depth control of multilayered III−V semiconductor samples with reflectance anisotropy spectroscopy (RAS) equipment

Kleinschmidt¹,

Barzen²,

Strassner³

et al. 2016

Beilstein J. Nanotechnol.

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Reflectance anisotropy spectroscopy (RAS) equipment is applied to monitor dry-etch processes (here specifically reactive ion etching (RIE)) of monocrystalline multilayered III–V semiconductors in situ. The related accuracy of etch depth control is better than 16 nm. Comparison with results of secondary ion mass spectrometry (SIMS) reveals a deviation of only about 4 nm in optimal cases. To illustrate the applicability of the reported method in every day settings for the first time the highly etch depth sensitive lithographic process to form a film lens on the waveguide ridge of a broad area laser (BAL) is presented. This example elucidates the benefits of the method in semiconductor device fabrication and also suggests how to fulfill design requirements for the sample in order to make RAS control possible.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Precise in situ etch depth control of multilayered III−V semiconductor samples with reflectance anisotropy spectroscopy (RAS) equipment

Kleinschmidt¹,

Barzen²,

Strassner³

et al. 2016

Beilstein J. Nanotechnol.

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“…In order to have an in situ (real-time) etch-depth control with this demanding accuracy we have successfully employed an adequate measurement techniques, by transferring the concept of reflectance anisotropy spectroscopy (RAS), which is well-known from epitaxy for growth control by now [29][30][31][32][33][34][35], to reactive ion etching (RIE) of monocrystalline semiconductor layer sequences [36][37][38][39]. We have used argon as the plasma gas and 2 volume-% of chlorine as the reactive gas.…”

Section: Technological Workmentioning

confidence: 99%

Fundamental Transverse Mode Selection (TMS#0) of Broad Area Semiconductor Lasers with Integrated Twice-Retracted 4f Set-Up and Film-Waveguide Lens

Fouckhardt

Kleinschmidt

Strassner

et al. 2017

Advances in OptoElectronics

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Previously we focused on fundamental transverse mode selection (TMS#0) of broad area semiconductor lasers (BALs) with two-arm folded integrated resonators for Fourier-optical spatial frequency filtering. The resonator had a round-trip length of 4f, where f is the focal length of the Fourier-transform element (FTE), that is, a cylindrical mirror in-between the orthogonal resonator branches. This 4f set-up can be called "retracted once" due to the reflective filter after 2f ; that is, the 2f path was used forwards and backwards. Now the branches are retracted once more resulting in a compact 1f long linear resonator (called "retracted twice") with a roundtrip length of 2f. One facet accommodates the filter, while the other houses the FTE, now incorporating a film-waveguide lens. The BAL facet with the filter represents both the Fourier-transform plane (after 2f, i.e., one round-trip) as well as the image plane (after 4f, two round-trips). Thus filtering is performed even after 4f, not just after 2f. Experimental results reveal good fundamental TMS for pump currents up to 20% above threshold and a one-dimensional beam quality parameter 2 1D = 1.47. The BALs are made from AlGaInAsSb, but the concept can equally well be employed for BALs of any material system.

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In-situ etch-depth control better than 5 nm with reflectance anisotropy spectroscopy (RAS) equipment during reactive ion etching (RIE): A technical RAS application

Doering¹,

Strassner²,

Fouckhardt³

2019

AIP Advances

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A measurement technique, i.e. reflectance anisotropy/difference spectroscopy (RAS/RDS), which had originally been developed for in-situ epitaxial growth control, is employed here for in-situ real-time etch-depth control during reactive ion etching (RIE) of cubic crystalline III/V semiconductor samples. Temporal optical Fabry-Perot oscillations of the genuine RAS signal (or of the average reflectivity) during etching due to the ever shrinking layer thicknesses are used to monitor the current etch depth. This way the achievable in-situ etch-depth resolution has been around 15 nm. To improve etch-depth control even further, i.e. down to below 5 nm, we now use the optical equivalent of a mechanical vernier scale– by employing Fabry-Perot oscillations at two different wavelengths or photon energies of the RAS measurement light – 5% apart, which gives a vernier scale resolution of 5%. For the AlGaAs(Sb) material system a 5 nm resolution is an improvement by a factor of 3 and amounts to a precision in in-situ etch-depth control of around 8 lattice constants.

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Influence of plasma composition on reflectance anisotropy spectra for in situ III–V semiconductor dry-etch monitoring

Cited by 7 publications

References 54 publications

Precise in situ etch depth control of multilayered III−V semiconductor samples with reflectance anisotropy spectroscopy (RAS) equipment

Precise in situ etch depth control of multilayered III−V semiconductor samples with reflectance anisotropy spectroscopy (RAS) equipment

Fundamental Transverse Mode Selection (TMS#0) of Broad Area Semiconductor Lasers with Integrated Twice-Retracted 4f Set-Up and Film-Waveguide Lens

In-situ etch-depth control better than 5 nm with reflectance anisotropy spectroscopy (RAS) equipment during reactive ion etching (RIE): A technical RAS application

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