Importance

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Abstract

According to the present invention, a silicon wafer, silicon dioxide wafer or silicon wafer having a silicon dioxide film thereon can be mutually adhered. The procedure for the adhesion is that a refractory metal, such as zirconium, is deposited by sputtering on a flat surface to be adhered, and tightly stacked onto another substrate made of silicon, silicon dioxide or silicon having a silicon dioxide film thereto, and the stacked wafers are heated in an atmosphere of argon containing 4% hydrogen at approximately 650.degree. C. for approximately 2 hours. The heat causes the deposited zirconium to react with the silicon of both the contacting wafers and is converted into a zirconium silicide alloy, which bonds the wafers. If the wafer is silicon dioxide or coated with silicon dioxide, the zirconium reduces the dioxide to produce silicon, which is then alloyed with the zirconium. Refractory metals other than group IVa and group Va elements can adhere silicon to silicon only. Advantages of this adhesion method are: the process is carried out at approximately 650.degree. C., which does not harm fabricated devices; the adhesion withstands temperatures of 1000.degree. C. which are used for fabricating devices; and the processing does not require strict control of the surface conditions. This method can be applied to the process of making SOI, a wafer-scale integrated LSi, or a three-dimensional LSI.

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First Claim