| 摘要 |
PROBLEM TO BE SOLVED: To obtain an alumina film having few pinholes and exhibiting good insulating property even in the case of a very small thickness by incorporating a specified proportion of at least one selected from MgO, La2O3 and Y2O3 into alumina. SOLUTION: The alumina film contains 10-30 wt.% at least one selected from MgO, La2O3 and Y2O3 as an additive component. Alumina containing at least one selected from MgO, La2O3 and Y2O3 as an additive component is used as an evaporation source 1 and physical vapor deposition is carried out. When the evaporation source 1 is heated with an energy source 2 such as an electron beam, a cluster 3 flies out, sticks to a substrate 4, causes surface migration and deposits as an alumina film 5. In the case of 500Åthickness of the alumina film 5, 8 MV/cm dielectric strength is ensured, and when such alumina films are used as the upper and lower lead gap layers of a thin film magnetic head, the interval between upper and lower shielding layers can be narrowed and high recording density is attained.
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