Theory of plasma chemical transport etching of gold in a chlorine plasma

Zarowin, C. B.

doi:10.1016/0040-6090(81)90052-3

Cited by 9 publications

(10 citation statements)

References 6 publications

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“…267) containing plasmas, but the samples were not heated, and sputtering rather than the creation of volatile compounds took place. When substrates were heated to 125 C and above, [268][269][270] Au etching rates in Cl 2 as high as 980 nm/min with 10:1 selectivity to the SiO 2 hardmask was realized. 270 There was no evidence of deposition on the sidewalls and 0.5 lm wide features, 1 lm high, appear to be vertical.…”

Section: Other Materialsmentioning

confidence: 99%

Plasma etching: Yesterday, today, and tomorrow

Donnelly¹,

Kornblit²

2013

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

650

422

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The field of plasma etching is reviewed. Plasma etching, a revolutionary extension of the technique of physical sputtering, was introduced to integrated circuit manufacturing as early as the mid 1960s and more widely in the early 1970s, in an effort to reduce liquid waste disposal in manufacturing and achieve selectivities that were difficult to obtain with wet chemistry. Quickly,the ability to anisotropically etch silicon, aluminum, and silicon dioxide in plasmas became the breakthrough that allowed the features in integrated circuits to continue to shrink over the next 40 years. Some of this early history is reviewed, and a discussion of the evolution in plasma reactor design is included. Some basic principles related to plasma etching such as evaporation rates and Langmuir–Hinshelwood adsorption are introduced. Etching mechanisms of selected materials, silicon,silicon dioxide, and low dielectric-constant materials are discussed in detail. A detailed treatment is presented of applications in current silicon integrated circuit fabrication. Finally, some predictions are offered for future needs and advances in plasma etching for silicon and nonsilicon-based devices.

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Section: Other Materialsmentioning

confidence: 99%

Plasma etching: Yesterday, today, and tomorrow

Donnelly¹,

Kornblit²

2013

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

650

422

View full text Add to dashboard Cite

show abstract

“…where the neutral reaction activation energy is E~ and the ion reaction activation energy is reduced from that of the neutral reaction by an amount U, taken as proportional to the ion kinetic energy (7). The total etch rate R, can then be written R = K[A]e -Er/~r (1 4-a+e t:/~T) [la] where a+ _--[A+]/[A] is the degree of ,ionization of the reactant A.…”

Section: S+a~-~bmentioning

confidence: 99%

“…We begin by identifying the generic neutral and ionic species reactions with the etch solid. These two reaction rates are related by assuming (7) that the ionic reaction activa-tion energy is smaller than the neutral reaction activation energy by an amount proportional to the kinetic energy obtained by the ion while crossing the sheath electric field. This assumption further stems .…”

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confidence: 99%

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Plasma Etch Anisotropy—Theory and Some Verifying Experiments Relating Ion Transport, Ion Energy, and Etch Profiles

Zarowin

1983

J. Electrochem. Soc.

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A model of plasma etch anisotropy is presented which shows that the ionic component of the chemical etch process produces etch profiles that vary with E/p , where E is the electric field controlling the ion transport to the etch surface and p is the etch gas pressure. From a relation derived here between E and the observable rf current density, Jnormalrf , this model predicts that the profiles will vary continuously from isotropically to anisotropically produced as the parameter Jnormalrf/p is increased. This behavior reflects the directionality of the ion kinetic energy transported to the etch surface and the effect of the ion energy in reducing the surface reaction activation energy. The one‐to‐one correspondence between ion energy and ion transport or etch directionality shown by this model clarifies the compromise required between etch anisotropy and the adverse effects of such high ion energy, such as reduced resist survival and selectivity against other materials in addition to the possibility of increased substrate damage. Another important practical consequence of this work is the establishment of a theoretical basis for extending the conventional wisdom that low pressures (<10 Pa) are required for anisotropic plasma etching to the more general requirement of a sufficiently high E/p ratio. Thus, this theory shows, and a wide range of experiments verify, that equally anisotropic etch profiles are obtainable at high (e.g., 1000 Pa) or low pressures from the same Jnormalrf/p ratios. Alternatively, it will be shown that reactive ion etching is a low pressure limiting case of plasma etching, both of which are able to produce identically anisotropic etch profiles, although the latter is capable of considerably higher etch rates. Finally, this model predicts a dependence of the anisotropy on the ion‐neutral scatterer collision cross section and/or mass ratio, which is experimentally confirmed here by previously unpublished data.

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“…This is similar to reactive ion etching (17,19), where the ions cross the sheath with negligibly few randomizing collisions and are thus transported across the sheath almost completely anisotropically, most often yielding an anisotropic etch process. Thus if this heterogeneous chemical process is dominantly controlled by ion bombardment, and if the ion flux is isotropic, the etching is expected to be isotropic.…”

Section: Modification Of Isotropy Of Ion Transport By the Sheath Fieldmentioning

confidence: 78%

Control of Plasma Etch Profiles with Plasma Sheath Electric Field and RF Power Density

Zarowin¹,

Horwath²

1982

J. Electrochem. Soc.

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In this paper it is shown that the plasma sheath electric field in which the etch sample is immersed controls the anisotropy of the etching of polysilicon films. These films are on wafers supported by the grounded electrode of a diode plasma etch reactor. The sheath electric field at the wafer supporting electrode is modified either by changing the rf power delivered to the plasma, or, at constant rf power, by application of d-c voltage to the rf driven electrode, With similar consequences to the etch profiles. The absence of mask undercut and vertical etch walls characteristic of an anisotropic etch process are observed above a certain threshold power density-sheath electric field, while below this threshold, the profiles become progressively more undercut until they are equal to the etch depth, as expected ofisotropic etch processes. The experimental results presented in this paper, demonstrate these effects for a CC14 containing gas mixture at a total pressure of 65 Pa (0.5 Torr). A similar power density and pressure dependence of the etch anisotropy has been reported previously in different plasma etch gas under comparable conditions. These results will be shown to be explicable in terms of the increase in the anisotropy of the transport of ions for increasing sheath field. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 138.251.14.35 Downloaded on 2015-03-16 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 138.251.14.35 Downloaded on 2015-03-16 to IP Publication costs o] this article were assisted by the Perkin-Elmer Corporation.

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Theory of plasma chemical transport etching of gold in a chlorine plasma

Cited by 9 publications

References 6 publications

Plasma etching: Yesterday, today, and tomorrow

Plasma etching: Yesterday, today, and tomorrow

Plasma Etch Anisotropy—Theory and Some Verifying Experiments Relating Ion Transport, Ion Energy, and Etch Profiles

Control of Plasma Etch Profiles with Plasma Sheath Electric Field and RF Power Density

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