Scalloping minimization in deep Si etching on Unaxis DSE tools

Lai, Shouliang; Johnson, D.; Westerman, Russ; Nolan, John J.; Purser, David; Devre, M. W.

doi:10.1117/12.472750

Cited by 7 publications

(5 citation statements)

References 5 publications

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“…To further investigate the underlying failure mechanism of the scallop nanostructure criteria, we designed silicon hole etching with different CDs and cycle times (recipe No. 5 in table S1) only the saturation of the depth/etch rate is reported in the literature [20]. It is noted that the viewing position of the scallop nanostructures in figures 3(e) and (f) is in the middle of the TSV holes, and the etching/deposition balance should be considered as a little 'excess etching' or almost 'proper balance' due to the slightly increased scallop size from the top to the bottom (figure S7).…”

Section: Resultsmentioning

confidence: 96%

“…In contrast to eliminating the scallop nanostructure, some research studies were conducted to minimize it. Lai et al [20] found that the roughness of the sidewall caused by the formation of the scallop nanostructure in the Bosch process was directly related to the etch rate, thus the size of the scallop nanostructure could be minimized by shortening the cycle time. Correspondingly, Roxhed et al [21] reduced the size of the scallop nanostructure to less than 1 µm by frequently switching the alternating etching process (shortening the etch time per cycle) in the Bosch process.…”

Section: Introductionmentioning

confidence: 99%

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The application of the scallop nanostructure in deep silicon etching

et al. 2020

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Micro/nanostructures with high aspect ratios in silicon wafers obtained by plasma etching are of great significance in device fabrication. In most cases, the scallop nanostructure in deep silicon etching should be suppressed. However, the scallop nanostructure could be applied in electronic device fabrication as characteristic information, which indicates the balance between deposition and etching. In this work, the applications of scallop nanostructures in etching process optimization and environmental protection are demonstrated. In addition, the minimum effect of the cycle time on the scallop size is reported for the first time. These results could bring new thoughts to the electronic devices related fields, such as micro-electro-mechanical systems (MEMS), silicon capacitors and advanced packaging.

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Section: Resultsmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

The application of the scallop nanostructure in deep silicon etching

et al. 2020

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“…Therefore, it was decided to include a 3 s oxygen only step at a flow rate of 30 sccm, between etch and passivation steps, which reduced etch selectivity to 9.6:1. Furthermore, an unacceptable amount of 'scalloping' was observed with the first DRIE recipes, which was diminished through decreasing the silicon etch step time (SF 6 ) from 6 to 3 s, which reduces the amount of silicon etched each step [70][71][72]. The oxygen only step may also have contributed to reduced scalloping [73,74].…”

Section: Discussionmentioning

confidence: 99%

Fabrication and modelling of fractal, biomimetic, micro and nano-topographical surfaces

et al. 2016

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Natural surface topographies are often self-similar with hierarchical features at the micro and nanoscale, which may be mimicked to overcome modern tissue engineering and biomaterial design limitations. Specifically, a cell's microenvironment within the human body contains highly optimised, fractal topographical cues, which directs precise cell behaviour. However, recreating biomimetic, fractal topographies in vitro is not a trivial process and a number of fabrication methods have been proposed but often fail to precisely control the spatial resolution of features at different lengths scales and hence, to provide true biomimetic properties. Here, we propose a method of accurately reproducing the self-similar, micro and nanoscale topography of a human biological tissue into a synthetic polymer through an innovative fabrication process. The biological tissue surface was characterised using atomic force microscopy (AFM) to obtain spatial data in X, Y and Z, which was converted into a grayscale 'digital photomask'. As a result of maskless grayscale optical lithography followed by modified deep reactive ion etching and replica molding, we were able to accurately reproduce the fractal topography of acellular dermal matrix (ADM) into polydimethylsiloxane (PDMS). Characterisation using AFM at three different length scales revealed that the nano and micro-topographical features, in addition to the fractal dimension, of native ADM were reproduced in PDMS. In conclusion, it has been shown that the fractal topography of biological surfaces can be mimicked in synthetic materials using the novel fabrication process outlined, which may be applied to significantly enhance medical device biocompatibility and performance.

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“…27 A few groups have reduced the sidewall RMS roughness (measured using AFM) below 10 nm. 28 disclose recipe or profile information for their smooth sidewall process; thus, it is not clear whether this process was associated with a large undercut.…”

Section: Gas Chopping For Nanoscale Etchingmentioning

confidence: 99%

Nanoscale pattern transfer for templates, NEMS, and nano-optics

Olynick

Liddle²,

Harteneck

et al. 2007

SPIE Proceedings

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Plasma etching is an enabling technology in nano optic, nanoelectronic devices, nano electro mechanical systems (NEMS) and nanoresolution templates for nano imprint lithography (NIL). With shrinkage, one must overcome significant challenges to meet the stringent profile and CD goals necessary for nanoscale applications. Using the example of Si nanoimprint template fabrication, we show how ion/sidewall/mask interactions can dominate feature profile evolution at the nanoscale and what to look for successful pattern transfer. Gas chopping or multiplexed etching, generally used for deep silicon etching, is often avoided at the nanoscale due to unacceptable undercut and sidewall scalloping. We demonstrate a multiplexed etching process in silicon with sub-5 nm amplitude scallops which is well suited for NEMS and nano optics applications and which reduces the deleterious role of ion/sidewall/mask interactions at the nanoscale.

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Scalloping minimization in deep Si etching on Unaxis DSE tools

Cited by 7 publications

References 5 publications

The application of the scallop nanostructure in deep silicon etching

The application of the scallop nanostructure in deep silicon etching

Fabrication and modelling of fractal, biomimetic, micro and nano-topographical surfaces

Nanoscale pattern transfer for templates, NEMS, and nano-optics

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