Transistor, semiconductor device, and electronic device
摘要
說明書
The atmosphere-side substrate supply chamber 2701 includes a plurality of cassette ports 2761. The cassette port 2761 can hold a plurality of substrates.
The surface temperature of the target is set to be lower than or equal to 100° C., preferably lower than or equal to 50° C., further preferably about room temperature (typified by 25° C.). In a sputtering apparatus for a large substrate, a large target is often used. However, it is difficult to form a target for a large substrate without a juncture. In fact, a plurality of targets are arranged so that there is as little space as possible therebetween to obtain a large shape; however, a slight space is inevitably generated. When the surface temperature of the target increases, in some cases, zinc or the like is volatilized from such a slight space and the space might expand gradually. When the space expands, a metal of a backing plate or a metal of a bonding material used for adhesion between the backing plate and the target might be sputtered and might cause an increase in impurity concentration. Thus, it is preferable that the target be cooled sufficiently.
Specifically, to efficiently cool the target, a metal having high conductivity and an excellent heat dissipation property (specifically copper) is used for the backing plate, or a sufficient amount of cooling water is made to flow through a water channel formed in the backing plate.
Note that in the case where the target includes zinc, plasma damage is alleviated by the deposition in an oxygen gas atmosphere; thus, an oxide from which zinc is unlikely to be volatilized can be obtained.
