The two-dimensional (2D) diffusion of self-interstitials (I) in crystalline Si, both at room temperature and at 800degreesC, has been studied by quantitative scanning capacitance microscopy measurements. The 2D I emission from an I source laterally confined down to submicrometer dimensions, obtained by low-energy implantation through a patterned oxide mask, has been observed. At room temperature, I diffusion was monitored by measuring the electrical deactivation of B corresponding to the diffusing interstitial tail and it was demonstrated that this deactivation is due to compensating levels introduced by defects in the Si band gap. At 800degreesC I diffusion was monitored by measuring the transient enhanced diffusion of B spikes due to interstitial supersaturation produced during the annealing. In both cases, a dependence of the I depth-penetration on the original source size has been shown. (C) 2004 American Vacuum Society.