CO+NH3 plasma etching for magnetic thin films

Inductively coupled plasma reactive ion etching of CoFeB magnetic thin films in a CH3COOH/Ar gas mixture

“…Most of the gas mixtures mentioned above do not strictly follow the RIE mechanism to etch different types of materials, instead they mainly rely on physical sputtering, oxidation and formation of a hydrocarbon protective layer on the film surface. The etching of CoFe thin films in a CO/NH 3 gas mixture has been reported by Kubota et al [7]. The results suggest that chemical reactions occurred between the CO radicals in the plasma and metal compounds of the film.…”

Reactive Ion Etching of NiFe Film with Organic Resist Mask and Metal Mask by Inductively Coupled Plasma

“…We have succeeded in developing that the ICP-RIE of NiFe with the etch mask of the organic photo-resist and Ti by using CHF 3 /O 2 /NH 3 discharges exchanging CHF 3 for CH 4 gas gradually. We shows that the organic photoresist mask can be applied the NiFe etching in that plasma conditions with the exception of requiring high aspect structures.…”

“…However one can not get rid of a degradation of the resultant structure due to residual chlorine and non-volatile products in the Cl 2 -based process. Also the RIE process for etching of NiFe and other magnetic materials were carried out under the CO/ NH 3 discharges [2][3][4]. It was indicated that producing volatile metal carbonyl proceed with the etching of NiFe.…”

Selective Etching of Magnetic Tunnel Junction Materials Using CO/NH3 Gas Mixture in Radio Frequency Pulse-Biased Inductively Coupled Plasmas

“…14,15) However, recently, owing to the corrosion of the etched MTJ material surface and the low etch selectivity over mask materials, the etching of MTJ materials using noncorrosive gases such as CO/NH 3 , CH 3 OH, and CH 4 has been investigated by many research groups. [16][17][18][19][20][21][22][23][24][25] When noncorrosive gases are used in the etching of MTJ materials, owing to the low vapor pressures of compounds formed between the MTJ materials and the noncorrosive etching gases, the problems such as low etch rates of MTJ materials, and low etch selectivity over mask materials, low etch anisotropy still remain even though the problems related to halogen gases such as corrosion can be eliminated.…”