Cr-Al-B系蒸着薄膜の電気的特性

抄録

In order to develop a new material for the thin film resistor with high resistivity and small TCR (Temperatrure Coefficient of Resistance), the electrical properties of thin films of Cr-Al-B ternary alloys deposited on 96% alumina substrates by using two-electron-beam evaporators have been investigated with particular reference to the effects of B content and heat treatment. The addition of B into the thin films of the 25 at%A1-Cr alloy caused the amorphization of bcc Cr-Al solid solution, and consequently no X-ray diffraction line from the bcc Cr-Al alloy could be found at B contents more than 20 at%. This amorphization was ac-companied by a remarkable decrease in resistivity and in the absolute value of negative TCR. At B contents more than 20 at%, however, the resistivity of the film increased largely with B content, while the change in TCR was rather small. It was suggested by X-ray photoelectron spectroscopy that this increase in the resistivity of the amorphous thin film with B content was related to the binding of Al with O supplied from the atmosphere during the deposition. After the heat treatment at 773 K for 3.6 ks, the electrical properties of the films with B contents less than 20 at% approached those of the Cr-Al binary alloy owing to the crystallization of the amorphous phase. At B contents more than 20 at%, on the other hand, no crystallization due to the heat treatynent could be found, and the electrical properties of the films were hardly influenced by the heat treatment. The crystallization of the films with B more than 20 at% occurred during the heat treatment above 900 K to form Cr-B and Cr-Al compounds with electrical properties quite different from those of the films in the amorphous state.