Ultra-thin Diamond Like-carbon Films For Magnetic Recording Sliders

With the development of magnetic disk drive technology, ultra-thin diamond-like carbon (DLC) films have attracted considerable interest as a protective overcoat. In this thesis, firstly, DLC films are deposited using electron cyclotron resonance (ECR) chemical vapor deposition,ion beam deposition optimization (IBO) and filtered cathodic vacuum arc (FCVA) techniques, respectively. Then we consider in detail the use of a combined study of Raman spectra taken at two wavelengths (514 and 244 nm) to study the structure of films that can reflect its properties, and this is highlight part of the thesis. In addition, we propose a method for ultra-thin DLC films adherence evaluation on the nano-scale lead area of magnetic recording slider. The details are as following:Firstly DLC films of different thickness from 10? to 100? are prepared by ECR-CVD,IBO and FCVA techniques, respectively. Through Raman spectroscopy study, the growth model for three kinds of films was discussed. For a-C:H films by ECR-CVD and IBO, its formation process mainly includes two stages. When film thickness is less than 50?, the carbon ions will form multiple nucleation centers like island, and when thickness is over 50?, the films developed with layer model and its structure became stable. But for ta-C films by FCVA, its growth process includes three stages. At the first stage, the thickness is less than 15? and it developed with island-like model. At the second stage, the thickness is from 15? to 50?, it developed with layer-like model and it already became stable. For the third stage, the thickness is over 50?, in mass area it could be described by layer model, while in local area it is with island model to form a little more tetrahedral structure. Thus, ta-C films of thickness over 15 ? already became dense and continuous and it will be the best choice for application of films in magnetic recording slider.By ECR-CVD with a mixed gas of CH4 and N₂, the structure and mechanical properties of the a-C:H:N films are studied. The results show that a-C:H:N films with higher N content will contain less sp³ sites. Hardness test of films confirmed that more N content corresponds to lower hardness. It also indicates that hard C≡N bond with high energy state is difficult to be formed by plasma doping, and additional N can not improve mechanical properties for a-C:H.The tetrahedral amorphous carbon (ta-C) films by FCVA have been studied as a function of oblique angles of substrates varied from 0 to 60o, while keeping the energy of incident particles stable. The films contain less sp³ sites and more ordered sp2 clustering as the substrate tilting for thicker films of 70 nm, and also a decrease of sp³ content of ultra-thin films of 2 nm. Also it was found that the tilting can dramatically lower internal stress with less influence on hardness because hardness is related to sp³ content, while internal stress is not only related to sp³ content but also related to the order of sp2 cluster.Additionally, substrate bias effect on ta-C film is studied. We found that the sp³ content of 70 nm films increases with higher bias, while sp³ content of 2 nm ultra-thin films falls almost linearly with bias. This is because substrate bias enhances mixing between the carbon films and substrate, and these mixing bonds are longer than C-C bonds. But for thicker films, the effect of mixing layer can be negligible compared to bias with higher carbon ion energy.The sliders are composed of multi-layers which are mainly Fe-Co (Fe: 67%at, Co: 33%at) alloy, Fe-Ni (Fe: 18%at, Ni: 82%at) alloy, Au and Al₂O₃-TiC (Al₂O₃: 64%at, TiC: 36%at). The spectra show that the films deposited on Al₂O₃-TiC contains the highest sp³ content, less sp³ content on Fe-Co and Fe-Ni alloy, and the lowest of sp³ content on Au substrate. It also indicates that the sequence of the anti-wear performance of ta-C film on different substrates is Al₂O₃-TiC > Fe-Co and Fe-Ni alloy > Au.Finally, we propose a method with ultra-sonic plus chemical etching test, for ultra-thin Si/DLC films adherence evaluation on the nano-scale lead area of magnetic recording slider. The adherences of films on both Au and Au-Cu (Au: 93%at, Cu: 7%at) based lead are compared, and the results show Au-Cu lead exhibits better adhesion to Si/DLC than that with Au as confirmed by nano-scratch tests from the wafer level.