Embedded pitch adapters: A high-yield interconnection solution for strip sensors

Abstract

a b s t r a c t A proposal to fabricate large area strip sensors with integrated, or embedded, pitch adapters is presented for the End-cap part of the Inner Tracker in the ATLAS experiment. To implement the embedded pitch adapters, a second metal layer is used in the sensor fabrication, for signal routing to the ASICs. Sensors with different embedded pitch adapters have been fabricated in order to optimize the design and technology. Inter-strip capacitance, noise, pick-up, cross-talk, signal efficiency, and fabrication yield have been taken into account in their design and fabrication. Inter-strip capacitance tests taking into account all channel neighbors reveal the important differences between the various designs considered. These tests have been correlated with noise figures obtained in full assembled modules, showing that the tests performed on the bare sensors are a valid tool to estimate the final noise in the full module. The full modules have been subjected to test beam experiments in order to evaluate the incidence of cross-talk, pick-up, and signal loss. The detailed analysis shows no indication of cross-talk or pick-up as no additional hits can be observed in any channel not being hit by the beam above 170 mV threshold, and the signal in those channels is always below 1% of the signal recorded in the channel being hit, above 100 mV threshold. First results on irradiated mini-sensors with embedded pitch adapters do not show any change in the interstrip capacitance measurements with only the first neighbors connected.

Prototyping of hybrids and modules for the forward silicon strip tracking detector for the ATLAS Phase-II upgrade

“…Details can be found in ref. [14]. The noise behaviour is measured to be uniform across all ASICs of a hybrid or module, respectively.…”

Prototyping of petalets for the Phase-II upgrade of the silicon strip tracking detector of the ATLAS experiment

“…In addition, two sensor types are available, a set with embedded pitch adapters to reduce the wire-bonding angle and a set with standard pitch adapters on each strip. The second metal layer of the embedded pad sensors leads to increased noise values depending on the length and geometry of the second metal layer traces [11,12]. These effect has to be taken into account when comparing the performance of petalets with modules built either from standard sensors or from embedded ones.…”

Sensors for the End-cap prototype of the Inner Tracker in the ATLAS Detector Upgrade

“…Small increases in the interstrip capacitance have been observed, which lead to an increase of the readout noise and its variation from channel to channel. New designs have been fabricated, and are being tested [11], to try and reduce these effects.…”