Mechanistic Considerations in Plasma-Assisted Etching of Ag and Au Thin Films

Choi, Tae-Seop; Levitin, Galit; Hess, Dennis W.

doi:10.1149/2.012306jss

Cited by 16 publications

(36 citation statements)

References 48 publications

(68 reference statements)

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“…One promising approach is the use of a H 2 plasma which has previously also been used to etch 'difficult' materials such as copper and silver. In the study of Hess and co-workers [29], the etching of gold film in an ICP reactor using a SiO 2 hard mask and H 2 , He and Ar plasmas was explored. Etch rates of 55 nm/min for He, 62 nm/min for Ar and 26 nm/min for H 2 plasmas were reported.…”

Section: Reactive Ion Etching Of Goldmentioning

confidence: 99%

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Gold etching for microfabrication

2014

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The etching of gold is a key enabling technology in the fabrication of many microdevices and is widely used in the electronic, optoelectronic and microelectromechanical systems (MEMS) industries. In this review, we examine some of the available methods for patterning gold thin films using dry and wet etching techniques. Dry methods which utilise reactive ion etching (RIE) have a number of important advantages over other methods, but the low volatility of gold etch products has made the development of suitable processes problematic. More recently, the adoption of high-density plasma reactors with optimised chlorine-based chemistries has allowed improved processes to be developed, and etching in hydrogen plasmas also shows promise. Wet etching methods for gold have also been critically reviewed. Traditionally, iodine-and cyanide-based etch processes have been used, but in the last decade, a number of alternative etchants have been studied. Of particular interest is the recent development of a range of novel nonaqueous-based gold etchants, and the suitability of these etchants for microfabrication is assessed.

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Section: Reactive Ion Etching Of Goldmentioning

confidence: 99%

“…For Ar and He, etching occurs predominantly by a sputtering process, but the low mass of hydrogen species indicates that observed etch rate must also have a chemical aspect. This would presumably occur by the formation of hydride species, but both AuH and AuH 2 − are known to have limited thermodynamic stability [29].…”

Section: Reactive Ion Etching Of Goldmentioning

confidence: 99%

Gold etching for microfabrication

2014

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“…In an H 2 plasma at 20 mtorr and 10 o C, Ag and Au film etch rates were higher (33 nm/min and 26 nm/min, respectively) than those of Cu (13 nm/min) (22). Analogous to Cu, Ag and Au hydrides are thermodynamically unstable, although the order of increasing stability is Ag, Cu, and Au (23 ) and small concentrations have been detected by IR spectroscopy at cryogenic temperature (23).…”

Section: Ag and Au Etchingmentioning

confidence: 97%

(Henry B. Linford Award for Distinguished Teaching Address) Low Temperature Plasma Etching of Copper, Silver, and Gold Films

Hess

2014

ECS Trans.

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Copper, silver and gold films possess unique electrical and optical properties that render them suitable for various device structures as employed in integrated circuits and plasmonic devices. Traditional etching of these metal films in halogenated plasmas is difficult due to the low vapor pressure of halogenated metal species. Reasonable etch rates of Cu, Ag, and Au films are obtained with hydrogen-based plasmas. Pattern formation with hydrogen and methane plasmas yields excellent selectivity to barrier materials such as Ta and Ti and generates metal wall slopes of ~80o.

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“…101 Because of the low metal bond energy, the reported sputter rate of Ag by various ions is generally higher than that of Cu and Au. 103 That is, the relative etch rate of Ag compared to Cu and Au is consistent with with these data if physical sputtering dominates Ag etching in H 2 plasmas.…”

Section: Silver Etching/patterning In H 2 and Chmentioning

confidence: 99%

Chemical Etching and Patterning of Copper, Silver, and Gold Films at Low Temperatures

Choi

Hess

2014

ECS J. Solid State Sci. Technol.

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Copper, silver, and gold share unique properties that offer numerous application possibilities. For instance, low resistivity and high electromigration resistance make them attractive as interconnect layers in integrated circuits and microelectronic devices, while the optical properties of their nano-scale structures allow fabrication of plasmonic devices. Etching or patterning techniques are required in order to fabricate nano-structures, devices, and circuits. Although liquid or vapor phase techniques can be applied, plasma or glow discharge methods are typically invoked due to the need to generate anisotropic nanometer pattern sizes. Group 11 metals (Cu, Ag, and Au) form few volatile compounds at temperatures below 150 • C, which limits the approaches that can be used to perform etching/patterning. Halogenated plasmas are widely used to etch metal layers; however, the low volatility of Cu, Ag, and Au halides precludes low temperature processes. Group 11 metals form hydrides readily in plasmas containing hydrogen species. Despite the thermodynamic instability of these metal hydrides, they appear to form at low (below room) temperature and can be desorbed from the etching surface by ion-or photon-assisted processes. Similarly, methylated metal etch products can be generated with hydrocarbon etching plasmas. As a result, etch rates above 12 ± 1 nm/min can be achieved, even when polymer forming plasmas (e.g., methane or other hydrocarbons) are used for patterning. These simple subtractive plasma etching approaches offer significant advantages relative to other vapor phase or liquid techniques in the manufacture of nano-scale devices and circuits.

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Mechanistic Considerations in Plasma-Assisted Etching of Ag and Au Thin Films

Cited by 16 publications

References 48 publications

Gold etching for microfabrication

Gold etching for microfabrication

(Henry B. Linford Award for Distinguished Teaching Address) Low Temperature Plasma Etching of Copper, Silver, and Gold Films

Chemical Etching and Patterning of Copper, Silver, and Gold Films at Low Temperatures

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