PSD9: The 9th International Conference on Position Sensitive Detectors

SLID-ICV Vertical Integration Technology with Thin Pixel Sensors for the ATLAS Pixel Upgrades

14 Sept 2011, 15:30

20m

Old College

Oral Presentation Detectors for High Radiation and Extreme Environments Advances in Pixel Detectors

Speaker

Philipp Weigell (MPI für Physik)

Description

A new pixel module concept for future ATLAS pixel detector upgrades is presented, where thin n-in-p sensors are connected to the front-end chip exploiting the novel Solid Liquid Interdiffusion technique (SLID) and the signals are read out via Inter Chip Vias (ICV) etched through the front-end. This should serve as a proof of principle for future four-side buttable pixel assemblies for the ATLAS upgrades, without the cantilever presently needed in the chip for the wire bonding. N-in-p pixel sensors with active thicknesses of 75\,$\mu$m and 150\,$\mu$m have been produced from wafers of standard thickness using a thinning process developed at the Max-Planck-Institut Halbleiterlabor. The pre-irradiation characterization of these sensors shows a very good device yield and high break down voltages. After irradiations up to a fluence of $10^{16}$\,n$_{\mathrm{eq}}$cm^{-2} Charge Collection Efficiency measurements yield higher values than expected from the present radiation damage models. The SLID interconnection, developed by the Fraunhofer EMFT, serves as a possible alternative to the standard bump-bonding. It is characterized by a very thin eutectic Cu-Sn alloy and allows for stacking of different layers of chips on top of the first one, without destroying the pre-existing bonds. This paves the way for vertical integration technologies. We will present the results of the characterization of the first pixel modules interconnected through SLID, performed with the ATLAS pixel read-out system USBPix. Besides the electrical properties and the connection efficiency also the mechanical strength of the interconnection was investigated. Additionally, the etching of ICV into the front-end wafers was started and the progress will be reported. ICVs will be used to route the signals vertically through the front-end chip, to newly created pads on the backside. In the EMFT approach the chip wafer is thinned to 50\,$\mu$m.

Preferred medium (Oral/poster)

Oral

Presentation materials

Slides

talk.pdf