A method for effecting adhesion of silicon or silicon dioxide plates

Abstract

Abstract In a procedure for effecting mutual adhesion of a silicon wafer, a silicon dioxide wafer or a silicon wafer (11, 12) having a silicon dioxide film (13, 14) thereon, a refractory metal, such as zirconium, is deposited by sputtering on a flat surface to be adhered, and tightly stacked on to another substrate (15) made of silicon, silicon dioxide or silicon having a silicon dioxide film thereon, and the stacked wafers are heated in an atmosphere of argon containing 4% hydrogen at approximately 650°C for 2 hours. By the heat, the deposited zirconium reacts with the silicon of both the contacting wafers and is converted into zirconium silicide alloy (18) 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 zirconium, titanium and hafnium can adhere silicon to silicon only. Advantages of this adhesion method are: the process is carried out at approximately 650°C which does not harm fabricated devices, but the adhesion withstands 1000°C which is used for fabricating devices, and the processing does not require strict control of the surface condition. This method is applied for making SOI, a wafer-scale integrated LSI, and three-­dimensional LSI.

Inventors

• 👤 Masaaki Fujitsu Limited Patent Department Muto
• 👤 Takashi Fujitsu Limited Patent Department Kato
• 👤 Takashi Fujitsu Limited Patent Department Ito

Bibliographic Details