Ion beam assisted organic chemical vapor etch of magnetic thin films

Abstract

An ion beam-assisted organic vapor etch process is demonstrated for patterning magnetic metal elements for potential applications in magnetoresistive random access memory devices. A thermodynamic analysis was performed to evaluate the feasibility of a chemical etch process, leading to the selection of acetylacetone (acac) and hexafluoroacetylacetone (hfac) chemistries. First, etching of cobalt and iron in acac and hfac solutions was studied, and it was determined that acac etches Co preferentially over Fe with a Co:Fe selectivity of ∼4, while hfac etches Fe preferentially over Co with an Fe:Co selectivity of ∼40. This motivates the use of acac and hfac to etch Co and Fe, respectively, but the etch rate was, in the gas phase, too small to be considered a viable process. An argon ion beam was employed in between organic vapor exposures and resulted in significant enhancement in the etch rates, suggesting an ion-enhanced chemical etching process is viable for the patterning of these magnetic metal elements.

Progress and prospects in nanoscale dry processes: How can we control atomic layer reactions?

“…95) A highly etching selectivity of the metal oxide relative to the metal by organic vapor was achieved, suggesting that one of the most important requirements in atomic layer etching, a self-limiting reaction, was 3 nm=min). 94) satisfied. 96) By tuning the oxide thickness generated by O 2 plasma exposure, the etching of metals can be controlled at an atomic level.…”

“…The volatility of the etching products was calculated to aid the selection of patterning chemistries, and this approach has been demonstrated successfully for test cases involving both halogen and organic etching chemistries. 93,94) One major consideration for enabling the ALEt of metallic and intermetallic thin films is the transformation of the metallic surface through physical or chemical means. Work on the use of Ar + in conjunction with acac chemistry has shown that ionic bombardment of cobalt thin films results in physical modification of the surface, generating additional active surface sites, disrupting the Co lattice by Ar bombardment, and allowing acac ligands to bond with Co to form Co(acac) 2 , using a cycle etching process.…”

“…14,186) A similar approach has been demonstrated using noble ion beam irradiation to physically modify preadsorption metal surfaces and remove volatile etching products with subsequent ion exposure. 94) In an effort to enable higher etching rates and achieve additional selectivity for the dry etching of metallic thin films, reactive oxygen plasmas have also been shown to be effective for the directional chemical modification of transition and noble metals through the generation of a thin metal oxide surface layer upon the application of a bias voltage to the substrate. Chen et al demonstrated the chemical contrast produced using reactive ion bombardment with the subsequent delivery of vapor-phase organics to the modified surface, resulting in an anisotropic and self-limiting etching process capable of achieving greater selectivity to the underlying metal.…”

Run-Away Energetic Reactions in the Exhaust of Deposition Reactors

“…In order to mitigate the detrimental effects of downstream deposition and prevent disastrous results of thermal run-away, it is necessary to gain a fundamental understanding of the chemical processes taking place and further determine how these processes respond to changes in processing conditions [8]. The methods of thermodynamic assessment have been demonstrated as useful tools in estimating the ranges for the desirable and undesirable reaction products [9]. Further kinetic and mechanistic studies of the deposition process are needed to gain insight into the dynamics of the run-away reactions.…”

Получение наноразмерных пленок CoSiO на поверхности СoSi-=SUB=-2-=/SUB=- методом ионной имплантации

“…Наноразмерные структуры и пленки с различной шириной запрещенной зоны на основе Si могут применяться при создании различных структур типа металл−диэлектрик−полупроводник и полупроводник−диэлектрик−полупроводник, транзисторов и диодов сверхвысокой частоты, приборов солнечной энергетики и др. При создании таких структур наиболее перспективными являются кобальт и силициды кобальта [1][2][3][4]. В частности, для увеличения КПД солнечных элементов необходимо создавать структуры, которые интенсивно поглощают световое излучение в области энергий от 0.3-0.4 до 3.5−4 eV.…”