OCD metrology evaluation of p-MOS silicon recess with three dimensional design pattern

Optical critical dimension (OCD) metrology has been proven to be a fast, accurate, and non-destructive knob for in-situ monitoring of line width and profile. In order to main Moore's law, device dimension is moving towards 45nm technology node and beyond, it is becoming increasingly difficult to perform the in-situ evaluation for those complicated structures by either critical dimension scanning electron microscopy (CD-SEM) or atomic force microscopy (AFM). In this work, we come up with one specific 3D pattern to realize the 3D monitoring of p-MOS silicon recess (PSR) etch performance. The corresponding OCD library was identified and implemented on Nova OCD 3090 next. Several key floating parameters include PSR & shallow trench isolation (STI) trench depth, gate & active area (AA) CD, nitride spacer width and side wall angle (SWA). Good CD correlation between OCD and CD-SEM is obtained on the same 3D pattern. Consistent trench depth match is also observed between OCD and blanket pattern based AFM. Besides, dynamic repeatability test shows the acceptable reliability for 3D PSR OCD monitoring as well.