We present here a new method for shaping a pulsed IR (λ = 1550nm) laser beam in silicon. The shaping is based on the plasma dispersion effect (PDE). The shaping is done by a second pulsed pump laser beam at 532nm (in either a Gaussian mode or a donut mode) which simultaneously and collinearly illuminates the silicon's surface with the IR beam. Following the PDE, and in proportion to its spatial intensity distribution, the 532nm laser beam shapes the point spread function (PSF) by controlling the lateral transmission of the IR probe beam. The use of this probe in a laser scanning microscope allows imaging and a wide range of contactless electrical measurements in silicon integrated circuits (IC) being under operation. We propose this shaping method to overcome the diffraction resolution limit in silicon microscopy on and deep under the silicon surface.