As interconnect dimensions shrink, achieving the required accuracy becomes increasingly difficult for existing in-line metrology methods. Non-destructive, small spot X-ray fluorescence (µ-XRF) can accurately measure copper interconnect thickness on various line space test structures as well as in the open spaces. Back-end metallization stacks have become more and more complex. Today's state of the art copper back-end process requires deposition of a semi-metal adhesion layer (TaN) followed by a diffusion barrier (Ta), followed by a PVD copper seed, and then by electro-deposition of bulk copper. To minimize yield loss to oxidation, all deposition steps are closely spaced in time, thus delaying metrology control until after the complete stack deposition. Tightly integrated deposition operations have increased the requirements for thickness metrology control. To provide deposition feedback as well as CMP feed-forward control, a metrology technique must accurately measure the thick copper layer and be sensitive enough to measure sub 50 Å barrier layer as well.


Jordan Valley XRR/XRF technology provides a small spot capable of measuring the entire back-end stack in scribe lines, and without the resolution limitations associated with laser acoustic techniques. Measurements include thickness, density and phase control. With advanced XRF capability, Jordan Valley X-ray metrology answers the challenges of metal back-end process control at the 65nm node level and beyond.

In addition, the thinning of copper lines becomes a roadblock as design rules shrink and more accurate measurement resolution is needed.

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Measurements on copper pads are no longer sufficient, as they don't represent the structures used in the device, so the JVX systems measure line/space structures for copper thickness and erosion.

Measuring copper thinning on different line/space structures on product is critical to controlling today's advanced interconnect processes as the erosion varies with line density.

Copper thickness, measured by Jordan Valley µ-spot XRF, correlates strongly with cross-sectional SEM data on a broad range of thicknesses and array structures.

Copper thickness, measured by Jordan Valley µ-spot XRF, correlates very strongly to sheet resistance on different patterned line/space structures.