1. 신개념 하지층에 관한 연구 - Cr 씨앗층， $Cr_75Ti_25$ 중간층，기판 바이어스 인가 방법으로 CoTi 하지층의 실용화 연구를 연구를 수행함으로써 4000 Oe의 고보자력 매쳬 제조에 성곡하였음 - Read/Write 특성평가 결과，CoTi 하지층은 기존의 Cr 하지층에 비하여 신호특성이 매우 양호함을 알 수 있으며， $Cr_75Ti_25$ 중간층의 삽입은 CoTi 하지층의 대체 효과를 더욱 향상 시켰음． - Co 합금계 자성박막층과 결정구조가 같은 CoCrMn
1. 신개념 하지층에 관한 연구 - Cr 씨앗층， $Cr_75Ti_25$ 중간층，기판 바이어스 인가 방법으로 CoTi 하지층의 실용화 연구를 연구를 수행함으로써 4000 Oe의 고보자력 매쳬 제조에 성곡하였음 - Read/Write 특성평가 결과，CoTi 하지층은 기존의 Cr 하지층에 비하여 신호특성이 매우 양호함을 알 수 있으며， $Cr_75Ti_25$ 중간층의 삽입은 CoTi 하지층의 대체 효과를 더욱 향상 시켰음． - Co 합금계 자성박막층과 결정구조가 같은 CoCrMn계 하지층을 발명함으로써 초기천이층이 없으면서도 입자크기분포가 균일한 자성기록층을 제조할 수 있게 되었음． 2. 초고밀도용 자성박막 제조 기술에 관한 연구 - FePt 자성박막의 제조조건을 최적화함으로써 4000 Oe 이상의 높은 보자력과 0.3 memu/$cm^2$ 이하의 낮은 Mr$\times$사 값을 갖는 극박막을 450 $^{circ}C$ 내외의 비교적 낮은 열처리 온도에서 얻는데 성공하였음． - MgO(111) 하지막 도입으로 10nm 두께의 FePt 박막에서 보자력 각형비가 0.8까지 증 가하였으며，보자력은 더욱 증가하였음． - CO 사이층，CrMO 삽입층 등 새로운 구조를 갖는 AFC 매체에 대하여 연구한 결과 열 적 안정성이 20% 이상 향상된 자기기록층을 개발하였음． 3. DLC（다이아몬드상 탄소） 보호층에 관한 연구 - 50$\AA$ 두께의 초박막 상태에서 ‘Cs 이온 지원 스퍼터’ 기술을 적용하여 기존의 것에 비하여 마찰계수가 작고 표면의 평활도가 좋은 DLC 박막 제조 성공 - 신공정기술로 제조한 DLC 박막은 트라이볼로지 특성이 우수하였는데，고습의 조건에서 특히 월등하였음．
Abstract▼
In order to push the superparamagnetic limit towards higher areal density it 15 impportant to control key media alloy parameters like magnetization, coercivity, intergranular exchange coupling and grain size. The present research has been conducted in order to optimize the foregoing key parameters a
In order to push the superparamagnetic limit towards higher areal density it 15 impportant to control key media alloy parameters like magnetization, coercivity, intergranular exchange coupling and grain size. The present research has been conducted in order to optimize the foregoing key parameters and divided into the following 5 subjects: (1) CoTi underlayer, (2) CoCrMn inderlayer, (3) FePt magnetic thin films, (4) AFC (Anti- Ferromagneticaily Coupled) media and micromagnetic modeling, (5) DLC (Diamond- Like Carbon) protective layer. 1. CoTi underlayer To make low noise media, the grain size of magnetic layer should be as small as possible and the size distribution of grains should be as narrow as possible. Also magnetic exchange interaction among grains of the magnetic layer should be small. The purpose of the work on this part is to develop a high coercivity and low noise media by introducing a new underlayer and to understand magnetic alld structurai properties by analyzing effects of the new underlayer on the grain size, crystallographic orientation and the composition of the magnetic layer. As a new underlayer, a B2 structured CoTi single layer, CoTi/Cr bilayer, and $Cr_75Ti_25$/CoTi bilayer were studied. Speciai attention was focused on: a. The effect of Cr seed layer on the microstructure and magnetic properties of CoCrPt/CoTi thin films b. The effect of $Cr_75Ti_25$ intermediate layer on the microstructure and magnetic properties of CoCrPt/CoTi thin films and the characteristics of Cr diffusion in the films c. The effect of the substrate bias on the microstructure and magnetic properties of CoCrPt/$Cr_75Ti_25$/CoTi thin films d. The read/write performance of the media having a new underlayer 2. CoCrMn underiayer The feasibihty of a underlayer of totally new concept was studied as a replacement of Cr or Cr alloy based underlayer which is widely used for Co alloy based magnetic layers. Highlighted are: a. The Crystallographic structure and the size variation of CoCrMn thin films as functions of the chemical composition, substrate temperature, deposition power and pressure, and the thickness of the films b. The effect of CoCrMn underlayer On the magnetic and the microstruvture properties of overlying CoCrPt magnetic layers c. The Origin of Mn effect On the microstructure of CoCrMn thin films 3. FePt magnetic thin films The number of grains per bit-cell controls the media noise and needs to be kept as high as possible. Shrinking the bit cell dimension, and thus increasing the data density, therefore requires the reduction of grain sizes leading to the problem of thermal instability. This will ultimately limit the achievable areal density for a given media material. New materials, however, with higher anisotropy (Ku) win be stable with smaller grain sizes. The cost of higher Ku is an increase in the field required to reverse the bit, or the write the data. Both of these effects are a direct consequence of temperature which acts in a statistical fashion to assist the magnetization reversal process. Considering both writeability and long term stability, we are exploring high Ku materials with the goal of optimizing them for data storage applications. We studied: a. The microstructure and magnetic propelties of FePt thin films as functions of the substrate temperature, and the thickness of the films b. The effect of annealing process on the magnetic and the microstructural properties of FePt thin films c. The effect of MgO underlayer On the magnetic and the microstructural properties of overlying FePt thin films 4. AFC (Anti-Ferromagnetically Coupled) media and micromagnetic modeling The new media structure consicts of two magnetic layers separated by a thin film of the element 겨thenium which produces an antiferromagnetic coupling of top and bottom magnetic layers. This ruthenium film is only about 3 atom layers in thickness permitting the effective magnetic thickness, Mrt, of this entire structure to be the difference between top and bottom magnetic films, therefore independent of actual individual layer thicknesses. Both magnetic layers can now be thicker at higher areal densities allowing larger diameter alloy grains which are more thermally stable. AFC media is expected to extend areal density growth to 100 Gbit/$in^2$ and beyond, while maintaining good thermal stability of the recorded information. In addition, refined micromagnetics model calculations are used to obtain a detailed understanding of the interdependencies between coercivity, intergranular exchange coupling and magneto-static interactions. reported here are: a. The mirostructure, magnetic properties, and thermal stability of AFC media with a Co interlayer b. The mirostructure, magnetic properties, and therrTlai stabllity of AFC media with a CrMo spacer layer c. Simulation on the effect of the thickness of the stabilizing layer and the crystalline anisotropy constant of each magnetic layer on the thermal stability of AFC media d. Simulation on the effect of the head field on writing process of AFC media 5. DLC (Diamond- Like Carbon) protective The carbon overcoats films used in layer hard disk drives are very thin and have to provide protection for the entire lifetime of the disk drive. Understanding how to make them in the form, how to characterize them, how they interacy with the lubticants, and how to prevent any chemical degration of the carbon are critical to moving the technology forward. We study many of the fundamentals which films which govern the friction and waer between sliders and disks using DLC films deposited by, so called, 'Cs ion assisted carbon sputtering process'. a. The tribological performance and hardness of DLC films deposited by 'Cs ion assisted carbon sputtering process' b. The microstructural characteristics and wettability of DLC films deposited by 'Cs ion assisted carbon sputtering process'
목차 Contents
제 1 장 연구개발과제의 개요...38
제 1 절 자기식 정보저장 장치...41
제 2 절 자기식 정보저장의 기본원리...43
제 3 절 자기기록매체의 종류 및 개발 약사...47
제 4 절 박막형 기록매체에 요구되는 특성...48
제 5 절 수평기록용 자성박막의 자기적 특성에 영향을 미치는 인자...57
제 6 절 박막형 기록매체의 구조 및 제조방법...64
제 2 장 국내외 기술개발 현황...67
제 1 절 박막형 기록매체의 고밀도화 기술 현황 및 전망...67
제 2 절 자기기록의 한계, 그 도전과 응전...70
제 3 장 연구수행 내용 및 결과...78
제 1 절 CoTi 하지막에 관한 연구...78
제 2 절 CoCrMn계 하지층에 관한 연구...118
제 3 절 FePt계 자성박막에 관한 연구...141
제 4 절 AFC 매체에 관한 연구...157
제 5 절 The Effects of Cesium Introduction on the Mechanical and Microstructural Properties of Sputtered Carbon Films...183
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