The Carborundum Company

Curtis E Zimmer

Thomas A Myles

A method for the preparation of pyrophosphates such as SiP.sub.2 O.sub.7 is disclosed, whereby the undesired formation of by-products such as Si.sub.2 P.sub.2 O.sub.9 is minimized. Such pyrophosphates are particularly suitable for the formation of solid semi-conductor diffusion sources, wherein the presence of by-product is seriously detrimental.

Preparation of pyrophosphates

Solid diffusion sources for phosphorus doping comprise from 10 to 95 percent SiP.sub.2 O.sub.7 with an inert phase of ZrP.sub.2 O.sub.7. Such materials may be hot-pressed to obtain diffusion source wafers of the appropriate dimensions and porosity. A preferred composition comprises from 25 to 75 weight percent SiP.sub.2 O.sub.7, the balance ZrP.sub.2 O.sub.7. Fabrication parameters range from about 750 psi to about 6,000 psi pressure during hot-pressing, at temperatures from about 800.degree.C to about 1450.degree.C.

Hot-pressed solid diffusion sources for phosphorus

Solid diffusion sources for phosphorus doping comprise from 5 to 95 percent SiP.sub.2 O.sub.7 with an inert phase of ZrP.sub.2 O.sub.7. While such materials may be hot-pressed, it is preferred to cold-press and sinter to obtain diffusion source wafers of the appropriate dimensions and porosity. A preferred composition comprises from 25 to 75 weight percent SiP.sub.2 O.sub.7 the balance ZrP.sub.2 O.sub.7. Fabrication parameters range from about 4000 psi to about 20,000 psi pressure during cold-pressing, and from about 1080.degree.C to about 1190.degree.C firing temperature.

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Curtis E Zimmer