| 학회 | 한국재료학회 |
| 학술대회 | 2016년 가을 (11/16 ~ 11/18, 경주 현대호텔) |
| 권호 | 22권 2호 |
| 발표분야 | A. 전자/반도체 재료 분과 |
| 제목 | Improving Thermal Stability of CoFeB Free Layer with [Co/Pt]6 Mulitlayers |
| 초록 | Nowadays, many people are actively researching about next generation memory. It needs some important characteristics such as high speed, small size, low price and high reliability. Spin-transfer torque magnetic random access memory (STT-MRAM) which is one of the next generation memories has high speed, high density, low power consumption and non-volatility. Therefore, it is fully expected to replace the dynamic randam access memory (DRAM). For commercialization of STT-MRAM, we must satisfy high tunnel magnetoresistance (TMR) ratio and appropriate thermal stability. Naturally, various structures and materials of magnetic tunnel junction (MTJ) have been actively researched. Thermal stability means the degree, in which the data is safely stored without thermal fluctuation. The value is determined by the equation, Δ=KuV/kBT. In this research, we focused on increasing Ku (Ku=Mk∙Hk/2) for high thermal stability, retaining perpendicular magnetic anisotropy (PMA) characteristic. To obtain high Ku, we stacked Co/Pt multilayers below the CoFeB free layer. CoFeB free layer coupling with Co/Pt multilayers can show both high thermal stability and PMA characteristic. In this experiment, we constructed MTJ composed of Ta(5nm) / Ru(3nm) / [Co(x) / Pt(x)]6 / CoFeB(x) / MgO(1.05nm) / Ta(2nm). We adjust Pt thickness from 0.2 to 0.4, Co thickness from 0.2 to 0.6 by the 0.1nm. With the optimized Co/Pt layer, we split CoFeB thickness from 0.8 to 1.3 by the 0.1nm. All samples are annealed from 250 to 350 by the 25℃. We measure M-H curve of each different sample using vibrating sample magnetometer (VSM) equipment. We can gain Ms, Hk, and Ku from this measurement and calculate thermal stability. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (No. 2014R1A2A1A01006474), IT R&D program MKE/KEIT (No. 10041608) in 2014 & Brain Korea 21 PLUS Program in 2014. |
| 저자 | Heon-Hak Ha1, Hun-Mo Yang2, Dong-Bum Seo1, Jong-Ung Baek2, Jin-Young Choi1, Dong-gi Lee2, Jea-Gun Park3 |
| 소속 | 1Department of Electronic Engineering, 2Hanyang Univ., 3Deparment of Nanoscale Semiconductor Engineering |
| 키워드 | Non-volatile; next-generation memory; advanced memory; STT-MRAM; TMR ratio; thermal stability |
