| AVS 59th Annual International Symposium and Exhibition | |
| Plasma Science and Technology | Thursday Sessions |
| Session PS-ThP |
| Session: | Plasma Science and Technology Poster Session |
| Presenter: | M.H. Jeon, Sungkyunkwan University, Republic of Korea |
| Authors: | M.H. Jeon, Sungkyunkwan University, Republic of Korea K.N. Kim, Sungkyunkwan University, Republic of Korea H.J. Kim, Sungkyunkwan University, Republic of Korea G.Y. Yeom, Sungkyunkwan University, Republic of Korea |
| Correspondent: | Click to Email |
Magnetic random access memory (MRAM) has made a prominent progress in memory performance and has brought a bright prospect for the next generation nonvolatile memory technologies due to its several advantages. Dry etching process of magnetic thin film is one of the important issues for the magnetic devices such as magnetic tunneling junctions (MTJs) based MRAM. MTJs which are the basic elements of MRAM can be used as bits for information storage. CoFeB is a well-known soft ferromagnetic material, of particular interest for magnetic tunnel junctions (MTJs) and other devices based on tunneling magneto-resistance (TMR), such as spintransfer-torque MRAM. Recently, transferring the pattern by using an Ar+ ion milling is a commonly used, although the redeposition of sputter etch products on the sidewalls and the low etch rate are main disadvantages of this method. Other method, which reported the etch rates higher than 50 Å/s for magnetic multilayer structures using Cl2/Ar plasmas, is also proposed. However, the chlorinated etch residues on the sidewalls of the etched features tend to severely corrode the magnetic material. To remove this problem, the etching of MTJ layer by using organic-based gases such as CO/NH3, CH3OH, etc. are actively investigated currently.
In this study, MTJ materials such as CoFeB, MgO, etc. were etched using various gas ratios which can be expected to form volatile metal-organic compounds and the results were compared with those etched using Cl2-based gas mixture. As one of the gas mixtures, gas mixtures of carbon monoxide (CO) and ammonia (NH3) were used as etching gases to form carbonyl volatiles. The etch results showed the enhanced etch rates higher than 3 times by using a gas mixture of CO/NH3 compared to that etched by pure CO or NH3 possibly indicating the formation of products composed of carbonyl volatiles. The composition of etched surface was less damaged compared with that etched with Cl2-based gas.