Fe-Zr-N 연자성 박막의 자기적 성질

Magnetic Properties of Fe-Zr-N Soft Magnetic Thin Films

RF magnetron reactive sputtering 법으로 Fe-Zr-N 박막을 제작하여 열처리 온도와 질소 분압의 변화에 따른 포화자화, 보자력, 고주파에서의 투자율 그리고 열적 안정성을 조사하였다. Fe-Zr-N 박막은 비정질과 결정질의 경계 조성인 $Fe_{72-78}Zr_{7-10}N_{15-18}$의 조성범위에서 연자성을 나타내었다. 이러한 박막은 포화자속밀도 1.55 T, 1 MHz에서의 실효 투자율은 3000 이상의 연자성을 나타내고 열처리 온도 $550^{\circ}C$ 까지도 실효투자율 2500 정도의 열적 안정성을 나타내었다. X-선 회절 분석 결과 열처리에 의해서 ZrN 미결정이 석출하여 $\alpha-Fe$ 결정 성장이 억제되어 우수한 연자기적 성질이 나타난다고 판단된다. 이때 $\alpha-Fe$ 입자 크기는 $40~50\AA$, ZrN의 입자 크기는 $10~15\AA$이었다.

Thin films of Fe-Zr-N were fabricated by rf magnetron reactive sputtering method. The saturation magnetization and coercivity as functions of annealing temperature and partial pressure of nitrogen gas, effective permeability at high frequencies, and thermal stability were investigated. Magnetic softness was exhibited in the composition range of $Fe_{72-78}Zr_{7-10}N_{15-18}$ which was boundary between polycrystalline and amorphous structure. These films exhibited magnetic softness with saturation magentic flux density of 1.55 T and effective permeability of about 3000 at 1 MHz. These films also exhibited thermal stability by sustaining effective permeability of 2500 or above as the temperature was raised to $550^{\circ}C$. It is asswned that good magnetic softness is obtained because grain growth of $\alpha-Fe$ is prohibited due to the precipitation of ZrN nanocrystals. The grain sizes of $\alpha-Fe$ films were $40~50\AA$ and the grain sizes of ZrN nanocrystals were $10~15\AA$.