MECHANISM OF GOLD DIFFUSION INTO SILICON

Gold was found to diffuse into Si by a complex mechanism involving a vacancy-controlled inter stitial-substitutional equilibrium. This led to very complex diffusion concentration profiles. In analyzing the problem, a new experimental value was found for the self-diffusion coefficient of Si, 1.81 x 10 to the 4th power exp (-112=20 kcal/RT)sq cm/sec, which compared very favorably with previous data on diffusion of Bi, Ge, and Sn in Si. The interstitial gold diffusion coefficient was found to be 2.4 x 10 to the minus 4th power exp (-8.9=2 kcal/RT), the substitutional gold-diffusion coefficient to be 2.75 x 10 to the minus 3rd power exp (-47=10 kcal/RT), the equilibrium-interstitial gold solubility to be 5.95 x 10 to the 24th power exp (-58=10 kcal/RT), and the equilibrium substitutional gold solubility (Collin's data) below 1200C to be 8.15 x 10 to the 22nd power exp (-40.6 kcal/RT). In cooperation with Pacific Semiconductors, Inc., Lawndale, CA.