This paper evaluates various optical metrology techniques for in-line control of the uniformity of 3D stacked structures. Advanced packaging technologies are rapidly evolving and 3D architectures require very well controlled process steps. Optical metrology techniques are now used for TSV but also for interconnect processing. In engineering mode, at the process implementation step, these techniques must be evaluated and then used to get uniform and repeatable processes. Among the 3D TSV Via middle process flow, the temporary bonding, wafer thinning and TSV reveal are key 3D process steps to get a uniform backside copper nail signature. High aspect ratio TSV are etched in Front End of the line and deep reactive ion etching systems generates radial non uniformities signatures. The wafer backside processing challenge consists in compensating this issue among the entire wafer surface. In this paper, all these process steps were characterized in order to quantify their specific intra-wafer dispersion signature .of the related key parameters. Cross correlation between the various intra-wafer process step signatures was then analyzed to verify the data set consistency and several process parameters analyzed to get a simple model. This model was then used to get a very uniform copper nail signature. For small diameter TSV and corresponding copper nails, a comparison has been done between full field OCT and confocal chromatic techniques.