Selective Etching of SiGe on SiGe / Si Heterostructures

Chang, Gee‐Kung; Carns, T. K.; Rhee, S. S.; Wang, K. L.

doi:10.1149/1.2085539

Cited by 32 publications

(15 citation statements)

References 1 publication

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“…In order to investigate the continuity of this thin Si layer over a much larger area, a novel method for chemically highlighting discontinuities was used. By exposing the thin Si capped SiGe decoration layer to a mixture of 1 part HF+ 2 parts H 2 O 2 + 3 parts acetic acid [20], microscopic discontinuities in the Si cap layer result in localized undercutting of the underlying reference SiGe layer. The resulting etch pits, if any, can be viewed easily over large areas using tilt-view SEM inspection.…”

Section: Resultsmentioning

confidence: 99%

Low-temperature growth of epitaxial (100) silicon based on silane and disilane in a 300mm UHV/CVD cold-wall reactor

Adam

Bedell

Reznicek

et al. 2010

Journal of Crystal Growth

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Section: Resultsmentioning

confidence: 99%

Low-temperature growth of epitaxial (100) silicon based on silane and disilane in a 300mm UHV/CVD cold-wall reactor

Adam

Bedell

Reznicek

et al. 2010

Journal of Crystal Growth

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“…[24][25][26] Furthermore, the substitution of water in the H2O2:HF:H2O mixture as the diluent by acetic acid (CH3COOH) increases the etch rate, selectivity, and etch uniformity of SiGe. 29 In these peroxideacid-based mixtures, 30 the high reactivity of the solution with SiGe is due to the acid-catalyzed formation of another oxidizing agent: peracetic acid (PAA or CH 3 CO 3 H). 31 Here, PAA is a product of the reaction between acetic acid and hydrogen peroxide:…”

Section: Resultsmentioning

confidence: 99%

Selective Wet Etching of Silicon Germanium in Composite Vertical Nanowires

Baraissov

Pacco

Koneti

et al. 2019

ACS Appl. Mater. Interfaces

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Silicon Germanium (SixGe1-x or SiGe) is an important semiconductor material for the fabrication of nanowire-based gate-all-around transistors in the next-generation logic and memory devices. During the fabrication process, SiGe can either be used as a sacrificial layer to form suspended horizontal Si nanowires or, because of its higher carrier mobility, SiGe can also be used as a possible channel material that replaces Si in both horizontal and vertical nanowires. In both cases, there is a pressing need to understand and develop nanoscale etching processes that enable controlled and selective removal of SiGe with respect to Si. Here, we developed and tested solution-based selective etching processes for SiGe in composite (SiNx/Si0.75Ge0.25/Si) vertical nanowires. The etching solutions were formed by 2 mixing acetic acid (CH3COOH), hydrogen peroxide (H2O2), and hydrofluoric acid (HF). Here, the two chemicals (H2O2 and CH3COOH) react to form highly oxidizing peracetic acid (PAA or). The hydrofluoric acid serves both as a catalyst for PAA formation and as an etchant for oxidized SiGe. Our study shows that an increase in either of the oxidizer concentrations increases the etch rate, and the fastest etch rate of SiGe is associated with the highest PAA concentration. Moreover, using in situ liquid phase TEM imaging, we tested the stability of nanowires during wet etching and identified that SiGe/Si interface to be the weakest plane; we found that once the diameter of the 160-nm-tall Si0.75Ge0.25 nanowire reaches ~15 nm during the etching, the nanowire breaks at or very close to this interface. Our study provides an important insight into the details of the wet etching of SiGe and some of the associated failure modes that are becoming extremely relevant for the fabrication processes as the size of the transistors shrink with every new device-generation.

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“…The peracetic acid (PAA) solutions were prepared by mixing 9.5 parts of H 2 O 2 (30 wt.%), 11 parts of acetic acid (98 wt.%), and 0.1 parts HF (49 wt.%). This etching solution is known to selectively etch Si x Ge 1-x alloys over pure Si [19, 20]. PAA, which acts as the oxidizing species for SiGe etching, is formed by reaction of the acetic acid with the peroxide with HF as catalyst.…”

Section: Experimental/methodsmentioning

confidence: 99%

Scaled-Down c-Si and c-SiGe Wagon-Wheels for the Visualization of the Anisotropy and Selectivity of Wet-Chemical Etchants

et al. 2019

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Wet etching offers an advantage as a soft, damage-less method to remove sacrificial material with close to nanometer precision which has become critical for the fabrication of nanoscale structures. In order to develop such wet etching solutions, screening of etchant properties like selectivity and (an)isotropy has become vital. Since these etchants typically have low etch rates, sensitive test structures are required to evaluate their etching behavior. Therefore, scaled-down single-crystalline Si (c-Si) and SiGe (c-SiGe) wagon-wheels were fabricated. First, the sensitivity of the c-Si wagon-wheels to detect anisotropic behavior of crystalline silicon in the alkaline etchants TMAH and NH 4 OH was demonstrated. Distinctive wagon-wheel patterns, characteristic for each material/etchant pair, were observed by top-down scanning electron microscopy (SEM) after anisotropic wet etching. Similar trends in crystallographic plane-dependent etch rates were obtained for both Si(100) and Si(110) substrates. Secondly, the etching of both c-Si and c-Si 75 Ge 25 wagon-wheels in a typical selective etchant, peracetic acid (PAA), was evaluated. c-Si 75 Ge 25 etching in PAA resulted in isotropic etching. Selectivity values were calculated based on two methods: the first by measurement of the sidewall loss of the spokes of the wagon-wheel, the second, indirect method, through measurement of the spoke retraction lengths. Both methods give comparable values, but the latter method can only be used after a certain critical etching time, after which the spoke tips have evolved toward a sharp tip. Electronic supplementary material The online version of this article (10.1186/s11671-019-3114-8) contains supplementary material, which is available to authorized users.

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Selective Etching of SiGe on SiGe / Si Heterostructures

Cited by 32 publications

References 1 publication

Low-temperature growth of epitaxial (100) silicon based on silane and disilane in a 300mm UHV/CVD cold-wall reactor

Low-temperature growth of epitaxial (100) silicon based on silane and disilane in a 300mm UHV/CVD cold-wall reactor

Selective Wet Etching of Silicon Germanium in Composite Vertical Nanowires

Scaled-Down c-Si and c-SiGe Wagon-Wheels for the Visualization of the Anisotropy and Selectivity of Wet-Chemical Etchants

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