Analysis of Nonuniformities in the Plasma Etching of Silicon with  CF 4 /  O 2

Kao, Alan S.; Stenger, Harvey G.

doi:10.1149/1.2086586

Cited by 6 publications

(5 citation statements)

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“…Silicon wafers processed with a plasma dry-etching process can show structures with unexpected deviations due to non-uniform plasma density, so that individual wafers made with the same recipe can differ from each other. Similar non-uniformities have been reported in the literature (Nagy 1984;Kao & Stenger 1990).…”

Section: Visualization Of the Nucleating Areasupporting

confidence: 91%

Heat-flux enhancement by vapour-bubble nucleation in Rayleigh–Bénard turbulence

et al. 2015

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We report on the enhancement of turbulent convective heat transport due to vapour-bubble nucleation at the bottom plate of a cylindrical Rayleigh-Bénard sample (aspect ratio 1.00, diameter 8.8 cm) filled with liquid. Microcavities acted as nucleation sites, allowing for well-controlled bubble nucleation. Only the central part of the bottom plate with a triangular array of microcavities (etched over an area with diameter of 2.5 cm) was heated. We studied the influence of the cavity density and of the superheat T b − T on (T b is the bottom-plate temperature and T on is the value of T b below which no nucleation occurred). The effective thermal conductivity, as expressed by the Nusselt number Nu, was measured as a function of the superheat by varying T b and keeping a fixed difference T b − T t 16 K (T t is the top-plate temperature). Initially T b was much larger than T on (large superheat), and the cavities vigorously nucleated vapour bubbles, resulting in two-phase flow. Reducing T b in steps until it was below T on resulted in cavity deactivation, i.e. in one-phase flow. Once all cavities were inactive, T b was increased again, but they did not reactivate. This led to one-phase flow for positive superheat. The heat transport of both one-and two-phase flow under nominally the same thermal forcing and degree of superheat was measured. The Nusselt number of the two-phase flow was enhanced relative to the one-phase system by an amount that increased with increasing T b . Varying the cavity density (69, 32, 3.2, 1.2 and 0.3 mm −2 ) had only a small effect on the global Nu enhancement; it was found that Nu per active site decreased as the cavity density increased. The heat-flux enhancement of an isolated nucleating site was found to be limited by the rate at which the cavity could generate bubbles. Local bulk temperatures of one-and two-phase flows were measured at two positions along the vertical centreline. Bubbles increased the liquid temperature (compared to one-phase † Email address for correspondence: daniela.narezo@gmail.com 332 D. Narezo Guzman and others flow) as they rose. The increase was correlated with the heat-flux enhancement. The temperature fluctuations, as well as local thermal gradients, were reduced (relative to one-phase flow) by the vapour bubbles. Blocking the large-scale circulation around the nucleating area, as well as increasing the effective buoyancy of the two-phase flow by thermally isolating the liquid column above the heated area, increased the heat-flux enhancement.

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Section: Visualization Of the Nucleating Areasupporting

confidence: 91%

Heat-flux enhancement by vapour-bubble nucleation in Rayleigh–Bénard turbulence

et al. 2015

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“…The following boundary conditions were used [11] [12] u=O v=O at z=-L and 0-r-<r~ [13] u=0 v=-v~ at z=L and 0-<t-<re [14] u=0 v=0 at z=L and re-r-<r~ [15] Ov u=0 --=0 at -L-<z-L and r=0 [16] Or [17] where u and v are the radial and axial components of the velocity vector. The gas velocity at the showerhead vw and the maximum velocity Um~ are given by…”

Section: V-u=0mentioning

confidence: 99%

“…Equation [14] is for a uniform gas entrance velocity at the showerhead electrode, and Eq. [16] is a result of radial symmetry. A well-developed parabolic velocity profile at the reactor exit was assumed (Eq.…”

Section: V-u=0mentioning

confidence: 99%

“…Recently there has been emphasis on plasma reactor modeling and diagnostics in order to improve our understanding of reactive gas plasmas, and to develop more rational procedures for plasma reactor design. Several investigators have conducted modeling and/or experimental studies of lowpressure plasma systems (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23). In each of these investigations, different aspects of the problem were emphasized.…”

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confidence: 99%

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Theoretical and Experimental Investigations of Chlorine RF Glow Discharges: I . Theoretical

Aydil

Economou

1992

J. Electrochem. Soc.

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A comprehensive model of chlorine plasma etching of polysilicon in a parallel plate reactor was developed. The Boltzmann transport equation and a bulk plasma model were used to calculate the rate coefficients of electron impact reactions. These coefficients were then used in a transport and reaction model to calculate the atomic chlorine concentration distribution. The same methodology may be applied to other plasma systems as well. Theoretical results for an empty reactor (no polysilicon film) are presented in this paper. Unified plots were developed which relate the electron density, self-sustained electric field, and electron impact coefficients in the bulk plasma to pressure, power, and reactor geometry. The calculated atomic chlorine concentration showed similar dependence on pressure and electrode spacing for either first or second order surface recombination kinetics. Experimental verification of the model predictions is presented in the accompanying paper.

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“…This finding indicates another superiority that S-LPD has no nonuniformity problem of RIE etching rate. 38 So far, applying S-LPD can avoid the problem of defects, contamination, rough-etched surfaces, and etching rate nonuniformity caused by RIE. These results preliminarily prove the superiority of S-LPD replacing RIE to form contact holes.…”

Section: Resultsmentioning

confidence: 99%

Application of Selective Liquid‐Phase Deposition to Fabricate Contact Holes Without Plasma Damage

Yeh¹,

Liu²,

Su³

1999

J. Electrochem. Soc.

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This work develops an alternative method, selective liquid‐phase deposition (S-LPD), to fabricate contact holes instead of reactive ion etching. In preliminary experiments, deep n+/normalp junction diodes with contact holes prepared by S-LPD exhibit much less reverse current, unity ideality factor, larger forward current, lower contact resistance, and higher thermal stability than those prepared by reactive ion etching. Further superiority of plasma damage‐free near‐surface regions is also investigated using Schottky and ultra‐shallow junction diodes. Experimental results indicate that S-LPD can be applied to the submicron contact‐hole process. The data after reverse bias temperature stress reveals the satisfactory reliability of S-LPD contact holes. This work demonstrates that the S-LPD technology is a highly promising means of replacing reactive ion etching processes to form submicron contact holes as reliably as those by wet‐etching. © 1999 The Electrochemical Society. All rights reserved.

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Analysis of Nonuniformities in the Plasma Etching of Silicon with CF 4 / O 2

Cited by 6 publications

References 5 publications

Heat-flux enhancement by vapour-bubble nucleation in Rayleigh–Bénard turbulence

Heat-flux enhancement by vapour-bubble nucleation in Rayleigh–Bénard turbulence

Theoretical and Experimental Investigations of Chlorine RF Glow Discharges: I . Theoretical

Application of Selective Liquid‐Phase Deposition to Fabricate Contact Holes Without Plasma Damage

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