| 摘要 |
PURPOSE:To enable precision etching of the insulating film on the lower magnetic pole of a thin film magnetic head by impressing a voltage or current of DC or AC between the lower magnetic pole of a water and a counter electrode, measuring the point of the time when the current or voltage attains a specified value and detecting the penetration of a joint hole. CONSTITUTION:''Permalloy'' is deposited as a lower electrode 1 on a silicon wafer 5. Silicon oxide of 1mum thickness is deposited as an insulating film 2 thereon and a photoresist is coated on said film by the conventional method. The photoresist is exposed and developed, thereby forming the resist pattern. 6% Hydrofluoric acid, 37% hydrogen peroxide, and 57% ammonium fluoride are used for an etching soln. 6 and said wafer 5 and a platinum electrode 7 are immersed oppositely at a 5cm space in said soln. A DC voltage 1V is impressed on the lower electrode 1 as a negative pole and the electrode 7 as a positive pole. When 10min elapses after conduction of electricity, the current increases sharply and saturates at 2A. A through-hole is formed in this stage and the metallic layer for the lower magnetic pole which is the bottom of the through- hole is not corroded. |
