Materials Science and Engineering B60 (1999) 107 – 111 Inductively coupled plasma etching of CoFeB, CoZr, CoSm and FeMn thin films in interhalogen mixtures H. Cho a , K.B. Jung a , D.C. Hays a , Y.B. Hahn a,1 , T. Feng a , Y.D. Park a , J.R. Childress b , F.J. Cadieu c , R. Rani c , X.R. Qian c , L. Chen c , S.J. Pearton a, * a Department of Materials Science and Engineering, Uniersity of Florida, Gainesille, FL 32611, USA b IBM Almaden Research Center, San Jose, CA 95120, USA c Physics Department, Queens College of CUNY, Flushing, NY 11367, USA Received 29 September 1998; received in revised form 9 February 1999; accepted 10 February 1999 Abstract Two new plasma chemistries (ICl and IBr) have been employed for patterning of CoFeB, CoZr, CoSm and FeMn thin films for application in magnetic memories. The interhalogen mixtures produced faster etch rates for FeMn, CoSm, and CoZr in both chemistries compared to Cl 2 plasmas under the same conditions. The etch rates are a strong function of discharge composition, pressure, ion flux and ion energy. The data are consistent with an ion-assisted desorption mechanism for the metal chloride etch products. No effect on magnetic properties of etched CoSm was detectable under our conditions. © 1999 Elsevier Science S.A. All rights reserved. Keywords: Plasma etching; Magnetic memories; Interhalogen mixtures; Magnetic properties 1. Introduction Since the discovery of the giant magnetoresistance (GMR) effect in antiferromagnetically coupled Fe/Cr multilayer structures [1,2] there has been a focus on optimizing the magnitude of this effect in ultra thin alternating layers of ferromagnetic metals and non- magnetic metals for magnetoresistive recording heads and sensor applications [3 – 5]. To increase bit storage densities using GMR heads, it is necessary to reduce the sensing layer coercivity and increase the GMR ratio, but in addition the track width should be reduced. Currently, these widths are 0.7 m for 10 Gbit in -2 recording densities. At smaller dimensions the pattern transfer processes become more critical. Currently, the magnetic multilayers are patterned by ion milling, due to the relative involatility of these materials in reactive ion etch (RIE) processes. Ion milling has some draw- backs for forming small features, including redeposition of sputtered material onto the feature sidewalls, and low selectivity for mask materials [4 – 6]. We have recently found that high density plasmas such as electron cyclotron resonance (ECR) and induc- tively coupled plasma (ICP) provide effective etching of NiFe and NiFeCo using a Cl 2 /Ar chemistry [7–9]. The high ion/reactive neutral ratios ( 0.02) in these tools provide a mechanism for overcoming the inherent low volatility of the metal-chloride etch products through efficient ion-assisted desorption. However, there is a strong interest in investigating other plasma chemistries (which might, for example, provide higher etch rates or less success over possible post-etch corrosion) and ex- tending the work to other materials. The latter include FeMn, a typical exchange pinning layer, and other Co-based magnetic sensing layers [10,11]. In this paper we report on an investigation of ICP etching of thin film FeMn, CoFeB, CoZr and CoSm in ICl and IBr plasma chemistries. These gases readily dissociate in high density plasma sources and might produce higher rates than Cl 2 -based etching. For exam- ple, CoI 2 has a much lower boiling point than CoCl 2 , suggesting that it would be advantageous to use I 2 -con- * Corresponding author. Tel.: +1-352-8461086; fax: +1-352- 8461182. 1 Present address: Department of Chemical Engineering and Tech- nology, Chonbuk National University, Chonju 561-756, Korea. 0921-5107/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved. PII:S0921-5107(99)00035-5