Multiple Parameter Characterization and Scanning Probe Microscopy for Inline Critical Dimension Metrology

Critical dimension metrology of integrated circuits has historically consisted of only single parameter characterization which was intended to be representative of the overall linewidth. However, different morphological patterns represented by a single parameter may cause the inability to delineate deviant morphologies. As linewidths continue to decrease, smaller variations in the linewidths begin to have significant impact in the resulting morphology and the pattern transfer function. Two new forms of inline metrology evaluation present the prospect of being able to distinguish shape and scale. Multiple parameter characterization (MPC) of scanning electron microscope intensity line profiles has shown the ability to distinguish deviations between nominal profiles and preset process margin templates. In addition, inline scanning prove microscopy (SPM) presents the ability to do morphological shape evaluation by nondestructive cross sectioning of critical dimension features by obtaining topographic z(x,y) mapping as a function of planar positioning of the scan system. The new metrology evaluation system combining scanning prove microscopy with multiple parameter characterization uses features such as "scale" (nm), "shape quality" (a weighted polynomial of process margin template deviation, 0-1), and "deviation bin" (a descriptor for type of deviation, A-Z). The use of both MPC and SPM presents the possibility of utilizing these metrology techniques to determine etch parameters inline.