Tuning the reflectivity of high contrast gratings based on silicon and silica by means of wet etching with hydrofluoric acid

Author(s):  
Tassilo Jacobitz ◽  
Stefanie Kroker ◽  
Thomas Käsebier ◽  
Ernst-Bernhard Kley ◽  
Andreas Tünnermann
2013 ◽  
Vol 136 ◽  
pp. 351-354 ◽  
Author(s):  
Zhijiang He ◽  
Weihai Cheng ◽  
Zebin Li ◽  
Ying Liu ◽  
Qiongrong Ou ◽  
...  

Author(s):  
Peizhen Hong ◽  
Qiang Xu ◽  
Jingwen Hou ◽  
Mingkai Bai ◽  
Zhiguo Zhao ◽  
...  

Abstract In 3D NAND, as the stack number increases, the process cost becomes higher and higher, and the stress problem becomes more and more serious. Therefore, the low cost and low stress plasma enhanced Tetraethyl orthosilicate (PE TEOS), compared to high density plasma (HDP) oxide, shows its superiority as pre-metal dielectric (PMD) oxide layer in 3D NAND. This paper explores the challenges in the application of PE TEOS in 3D NAND PMD oxide layer.In our experiments, both PE TEOS and HDP are employed as the PMD oxide for 3D NAND staircase protection. There is not any void found in the two oxide structures. However, oxide pitting is spotted in the subsequent diluted hydrofluoric acid wet etching in the PE TEOS split. Moreover, we observe that the top silicon nitride corrodes in hot phosphoric acid. We investigate the mechanism of PE TEOS oxide pitting and silicon nitride corroding, and propose two solutions: 1) HDP oxide + PE TEOS, and 2) PE TEOS + dry etching.Experimental results demonstrate that our solutions can well address the issue of PE TEOS oxide pitting and effectively protect the staircase structure. This work extends the application of PE TEOS oxide of which the cost and the stress are both low in 3D NAND.


2013 ◽  
Vol 52 (7R) ◽  
pp. 076503 ◽  
Author(s):  
Zhou Yifan ◽  
Chen Sihai ◽  
Samson Edmond ◽  
Alain Bosseboeuf

2018 ◽  
Vol 282 ◽  
pp. 107-112 ◽  
Author(s):  
Kana Komori ◽  
Jens Rip ◽  
Yukifumi Yoshida ◽  
Kurt Wostyn ◽  
Farid Sebaai ◽  
...  

Gate All-Around (GAA) is considered a key design feature for future CMOS technology. SiGe vs. Si selective etch is required for Si nanowire formation in GAA. It is confirmed the selective SiGe removal with commodity chemical (mixtures of hydrofluoric acid (HF), hydrogen peroxide (H2O2) and acetic acid (CH3COOH, HAc)), however the thick oxidized layer on Si NW was observed after commodity chemical process, which is indicated the significant Si NW loss. On the other hand, the formulated mixture ACT® SG-101, which is focusing on SiGe oxidizer, chemical pH, solvent polarity & corrosion inhibitor for chemical concept, was performed higher selectivity and lower Si loss than commodity chemical. The formulated mixture has also been used to form an inner spacer for cavity etch scheme and confirmed uniform cavity etch and inner spacer filling on topological test structure.


2021 ◽  
Vol 61 (6) ◽  
pp. 684-688
Author(s):  
Asaad K. Edaan Al-mashaal ◽  
Rebecca Cheung

Wet etching is a critical fabrication step for the mass production of micro and nanoelectronic devices. However, when an extremely corrosive acid such as hydrofluoric (HF) acid are used during etching, an undesirable damage might occur if the device includes a material that is not compatible with the acid. Polyimide thin films can serve as sacrificial/structural layers to fabricate freestanding or flexible devices. The importance of polyimide in microelectronics is due to its relatively low stress and compatibility with standard micromachining processes. In this work, a fast delamination process of a 4-μm-thin film of polyimide from a silicon substrate has been demonstrated. The films’ detachment has been performed using a wet-based etchant of HF acid. Specifically, the effect of HF concentration on the delamination time required to detach the polyimide film from the substrate has been investigated. This study is intended to provide the information on the compatibility of using polyimide films with HF, which can help in the design and fabrication of polyimide-based devices.


Author(s):  
Russell L. Steere ◽  
Eric F. Erbe ◽  
J. Michael Moseley

We have designed and built an electronic device which compares the resistance of a defined area of vacuum evaporated material with a variable resistor. When the two resistances are matched, the device automatically disconnects the primary side of the substrate transformer and stops further evaporation.This approach to controlled evaporation in conjunction with the modified guns and evaporation source permits reliably reproducible multiple Pt shadow films from a single Pt wrapped carbon point source. The reproducibility from consecutive C point sources is also reliable. Furthermore, the device we have developed permits us to select a predetermined resistance so that low contrast high-resolution shadows, heavy high contrast shadows, or any grade in between can be selected at will. The reproducibility and quality of results are demonstrated in Figures 1-4 which represent evaporations at various settings of the variable resistor.


Author(s):  
J.N. Turner ◽  
M. Siemens ◽  
D. Szarowski ◽  
D.N. Collins

A classic preparation of central nervous system tissue (CNS) is the Golgi procedure popularized by Cajal. The method is partially specific as only a few cells are impregnated with silver chromate usualy after osmium post fixation. Samples are observable by light (LM) or electron microscopy (EM). However, the impregnation is often so dense that structures are masked in EM, and the osmium background may be undesirable in LM. Gold toning is used for a subtle but high contrast EM preparation, and osmium can be omitted for LM. We are investigating these preparations as part of a study to develop correlative LM and EM (particularly HVEM) methodologies in neurobiology. Confocal light microscopy is particularly useful as the impregnated cells have extensive three-dimensional structure in tissue samples from one to several hundred micrometers thick. Boyde has observed similar preparations in the tandem scanning reflected light microscope (TSRLM).


Author(s):  
Uwe Lücken ◽  
Michael Felsmann ◽  
Wim M. Busing ◽  
Frank de Jong

A new microscope for the study of life science specimen has been developed. Special attention has been given to the problems of unstained samples, cryo-specimens and x-ray analysis at low concentrations.A new objective lens with a Cs of 6.2 mm and a focal length of 5.9 mm for high-contrast imaging has been developed. The contrast of a TWIN lens (f = 2.8 mm, Cs = 2 mm) and the BioTWTN are compared at the level of mean and SD of slow scan CCD images. Figure 1a shows 500 +/- 150 and Fig. 1b only 500 +/- 40 counts/pixel. The contrast-forming mechanism for amplitude contrast is dependent on the wavelength, the objective aperture and the focal length. For similar image conditions (same voltage, same objective aperture) the BioTWIN shows more than double the contrast of the TWIN lens. For phasecontrast specimens (like thin frozen-hydrated films) the contrast at Scherzer focus is approximately proportional to the √ Cs.


Author(s):  
Akira Tonomura

Electron holography is a two-step imaging method. However, the ultimate performance of holographic imaging is mainly determined by the brightness of the electron beam used in the hologram-formation process. In our 350kV holography electron microscope (see Fig. 1), the decrease in the inherently high brightness of field-emitted electrons is minimized by superposing a magnetic lens in the gun, for a resulting value of 2 × 109 A/cm2 sr. This high brightness has lead to the following distinguished features. The minimum spacing (d) of carrier fringes is d = 0.09 Å, thus allowing a reconstructed image with a resolution, at least in principle, as high as 3d=0.3 Å. The precision in phase measurement can be as high as 2π/100, since the position of fringes can be known precisely from a high-contrast hologram formed under highly collimated illumination. Dynamic observation becomes possible because the current density is high.


Author(s):  
A. Olsen ◽  
J.C.H. Spence ◽  
P. Petroff

Since the point resolution of the JEOL 200CX electron microscope is up = 2.6Å it is not possible to obtain a true structure image of any of the III-V or elemental semiconductors with this machine. Since the information resolution limit set by electronic instability (1) u0 = (2/πλΔ)½ = 1.4Å for Δ = 50Å, it is however possible to obtain, by choice of focus and thickness, clear lattice images both resembling (see figure 2(b)), and not resembling, the true crystal structure (see (2) for an example of a Fourier image which is structurally incorrect). The crucial difficulty in using the information between Up and u0 is the fractional accuracy with which Af and Cs must be determined, and these accuracies Δff/4Δf = (2λu2Δf)-1 and ΔCS/CS = (λ3u4Cs)-1 (for a π/4 phase change, Δff the Fourier image period) are strongly dependent on spatial frequency u. Note that ΔCs(up)/Cs ≈ 10%, independent of CS and λ. Note also that the number n of identical high contrast spurious Fourier images within the depth of field Δz = (αu)-1 (α beam divergence) decreases with increasing high voltage, since n = 2Δz/Δff = θ/α = λu/α (θ the scattering angle). Thus image matching becomes easier in semiconductors at higher voltage because there are fewer high contrast identical images in any focal series.


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