| 摘要 |
PURPOSE:To improve the reproducibility of a tunnel barrier, by keeping the period that a sputter target is exposed to the air for exchanging a substrate to be constant in every cycles. CONSTITUTION:The vacuum vessel of a sputtering equipment is leaked as fas as the atmospheric pressure by using nitrogen gas. At this time, an exhaust valve is closed. A door for substrate exchange is opened, and a new substrate is mounted on a substrate holder. The door is closed and vacuum exhaust is started. In a series of works, the period that an MgO target for a tunnel barrier is exposed to the air is set to be a constant value, e.g. 5 minutes. When an insulating film is deposited and formed as a tunnel barrier, the amount of water content, oxygen, etc., which are absorbed from the air by the sputter target in the case of substrate exchange becomes constant, so that the deposition speed of the insulating film exhibits a constant value, and the reproducibility of tunnel barrier thickness can be improved.
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