Advanced time-multiplexed plasma etching of high aspect ratio silicon structures

Blauw, M. A.; Crăciun, G.; Sloof, Willem G.; French, P.J.; Drift, E. van der

doi:10.1116/1.1518018

Cited by 50 publications

(30 citation statements)

References 10 publications

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“…Although not pursued in the current study, profile control with further precision may be possible by fine tuning the etch parameters and consulting the relevant literature. [54][55][56][57][58][59] Figures 4(a) and 4(b) show etched large square fields (p ¼ 5 lm, s ¼ 7 lm) before and after removal of the sacrificial structures, respectively. The sacrificial structures partially collapsed during the wafer cleaning and SiO 2 etching after DRIE, but were completely removed from the wafer surface and structures.…”

Section: Resultsmentioning

confidence: 99%

Sacrificial structures for deep reactive ion etching of high-aspect ratio kinoform silicon x-ray lenses

Stöhr

Michael-Lindhard

Hübner

et al. 2015

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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O. (2015). Sacrificial structures for deep reactive ion etching of high-aspect ratio kinoform silicon x-ray lenses. Journal of Vacuum Science and Technology. Part B. Microelectronics and Nanometer Structures, 33(6), [062001]. DOI: 10.1116/1.4931622 Sacrificial structures for deep reactive ion etching of high-aspect ratio kinoform silicon x-ray lenses This article describes the realization of complex high-aspect ratio silicon structures with feature dimensions from 100 lm to 100 nm by deep reactive ion etching using the Bosch process. As the exact shape of the sidewall profiles can be crucial for the proper functioning of a device, the authors investigated how sacrificial structures in the form of guarding walls and pillars may be utilized to facilitate accurate control of the etch profile. Unlike other sacrificial structuring approaches, no silicon-on-insulator substrates or multiple lithography steps are required. In addition, the safe removal of the sacrificial structures was accomplished by thermal oxidation and subsequent selective wet etching. The effects of the dimensions and relative placement of sacrificial walls and pillars on the etching result were determined through systematic experiments. The authors applied this process for exact sidewall control in the manufacture of x-ray lenses that are very sensitive to sidewall shape nonuniformities. Compound kinoform lenses for focusing hard x-rays with structure heights of 200 lm were manufactured, and the lenses were tested in terms of their focusing ability and refracting qualities using synchrotron radiation at a photon energy of 17 keV. A 180 lm long line focus with a waist of 430 nm at a focal length of 215 mm was obtained.

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Section: Resultsmentioning

confidence: 99%

Sacrificial structures for deep reactive ion etching of high-aspect ratio kinoform silicon x-ray lenses

Stöhr

Michael-Lindhard

Hübner

et al. 2015

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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“…The process conditions were given in Table I. The duration of the deposition step was 60 s. It is seen that highly anisotropic etch profiles of silicon could be obtained using SF 6 and C 4 F 8 plasmas in the etching and deposition steps of the Bosch process, respectively, under the process conditions used in this study. SEM was taken without ashing and cleaning of the etched samples, so some fluorocarbon polymers on the sidewalls can be seen.…”

Section: Methodsmentioning

confidence: 99%

“…SF 6 and C 4 F 8 are mainly used in the etching and deposition steps of the Bosch process, respectively. [3][4][5][6][7][8] However, C 4 F 8 ͑octafluorocyclobutane͒ is perfluoro carbon ͑PFC͒, which is considered to be problematic from an environmental point of view because of its long atmospheric lifetime, high global warming potential, and strong infrared absorption.…”

Section: Introductionmentioning

confidence: 99%

“…[3][4][5][6][7][8] However, C 4 F 8 ͑octafluorocyclobutane͒ is perfluoro carbon ͑PFC͒, which is considered to be problematic from an environmental point of view because of its long atmospheric lifetime, high global warming potential, and strong infrared absorption. [9][10][11] Originally, PFCs have been extensively used as etchants for silicon and silicon dioxide in microelectronics industries.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of deep silicon etching using SF6/C4F8 and SF6/C4F6 plasmas in the Bosch process

Rhee¹,

Kwon²,

Kim³

et al. 2008

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Silicon was etched with the Bosch process using C4F8 and C4F6 plasmas in the deposition step to show a feasibility of the use of UFC plasmas in the Bosch process. The use of C4F8 and C4F6 plasmas resulted in different characteristics of fluorocarbon films and radicals, affecting the etch profiles. It was shown that the use of a C4F6 plasma in the deposition step of the Bosch process produced thicker and more strongly bonded fluorocarbon films, compared to a C4F8 plasma. It was because more CF2 radicals and lower F/C ratio fluorocarbon films were generated in C4F6 plasmas than those in C4F8 plasmas, confirmed by OES and XPS measurements. By changing only the duration of the deposition step under the same process conditions, highly anisotropic deep etching of silicon was successfully achieved using both SF6/C4F8 and SF6/C4F6 plasmas in the etching and/deposition steps of the Bosch process.

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“…In two-step Bosch recipes, the depassivation is performed during the initial portion of the etching step. To introduce an individual depassivation step to the recipe, a third plasma pulse can be added in between the two passivation and etching steps [13]. Interestingly, the application of a short oxygen plasma pulse as a depassivation step has proven to be very successful in etching sub-m trenches with very high aspect ratios [14].…”

Section: Trench Etchingmentioning

confidence: 99%

A Gap Reduction and Manufacturing Technique for Thick Oxide Mask Layers With Multiple-Size Sub-<tex>$mu$</tex>m Openings

Abdolvand

Ayazi

2006

J. Microelectromech. Syst.

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This paper introduces a technique for the fabrication of thick oxide hard masks on top of a substrate with adjustable opening sizes in the sub-m regime, while the only lithography step involved has m-scale resolution. This thick oxide mask layer with sub-m openings is suitable for etching deep narrow trenches in silicon using deep reactive ion etching (DRIE) tools. Openings of less than 100 nm are realized in a 1.5-m-thick oxide layer, while the original lithographically defined feature sizes are larger than 1 m in width. This method, combined with modified high aspect ratio DRIE recipes, shows a great potential for single-mask batch-fabrication of high frequency low-impedance single crystalline resonators on silicon-on-insulator (SOI) substrates. Dry-etched trenches with aspect ratios as high as 60:1 are fabricated in silicon using the gap reduction technique to realize 200 nm opening sizes in an oxide mask layer. Various resonator structures with sub-m capacitive gaps are also fabricated on a SOI substrate using a single-mask process. Measurement results from high-frequency and high-quality factor (Q) all single crystal silicon resonators are presented.[1684]Index Terms-Deep reactive ion etching (DRIE), gap reduction, high aspect ration trench, sub-m gap.

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Advanced time-multiplexed plasma etching of high aspect ratio silicon structures

Cited by 50 publications

References 10 publications

Sacrificial structures for deep reactive ion etching of high-aspect ratio kinoform silicon x-ray lenses

Sacrificial structures for deep reactive ion etching of high-aspect ratio kinoform silicon x-ray lenses

Comparison of deep silicon etching using SF6/C4F8 and SF6/C4F6 plasmas in the Bosch process

A Gap Reduction and Manufacturing Technique for Thick Oxide Mask Layers With Multiple-Size Sub-<tex>$mu$</tex>m Openings

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