Status of technologies Mauro Citterio INFN Milano MPI/Munich 12 February 2009

Baseline for SLHC Roadmap for phase II (present Hp) 2yrs ~ 6 yrs LoI TDR Shutdown (new installations) Activities Production ~ 2yrs R&D Prototypes MPI/Munich 12 February 2009

Programs for the Atlas upgrades SiGe tecnology is a viable solution for a new LAr electronics Mostly for the analog part of the front-end electronics The importance of investigating such a technology is recognized in the “Expression of Interest”: R&D Towards the Replacement of the Liquid Argon Calorimeter Front End Electronics for the SLHC (ATU-RD-MN-0001 v.1, 11 February 2008) e dal programma di ricerca gia’ approvato: Evaluation of Silicon-Germanium (SiGe) Bipolar Technologies for Use in an Upgraded ATLAS Detector (ATL-P-MN-0007, 18 June 2006) SiGe is of interest for the inner detector also, an ATLAS common project exists: There are different requirements for the front-ends of the ATLAS LAr and the ID at sLHC ID needs real RADHARD chips ID front end must be an analog/digital ASICs MPI/Munich 12 February 2009

SLHC expected Fluence Levels ATLAS Upgrade Radiation Simulation Studies MPI/Munich 12 February 2009

Dose Levels from the Same Study MPI/Munich 12 February 2009

Radiation Environment No specification for radiation levels exist so far But based upon preliminary simulation studies and to be consistent with what the silicon sensor group is testing to, the present targets are the following levels (which include one safety factor of 2). Short Strips 6.8x1014 neq/cm2 30 Mrad Long Strips 3.2x1014 neq/cm2 8.4 Mrad LAr 9.6x1012 neq/cm2 30 krad  LAr will benefits from the extensive rad-tests performed to qualify SiGe for ID use Some preliminary rad-test results exists (mostly on IBM technology ….) MPI/Munich 12 February 2009

The Common project proposal The proposal submitted on Jun-2006 The following institutions are part of the proposal: USA BNL S.Rescia Columbia Nevis G.Brooijmans LBNL H.Spieler UC Santa Cruz A.A.Grillo U of Pennsylvania M. Newcomer Italy INFN - Milan M. Citterio Spain CNM Barcelona M. Ullan France IN2P3 C. De La Taille MPI/Munich 12 February 2009

The objective New generations of bipolar technologies have been commercialized … . These new technologies, which make use of a “strained lattice” silicon-germanium (SiGe) base region to form a heterostructure bipolar transistor (HBT), show promise to meet the demands of the upgraded ATLAS detector and reduce power consumption Specifically, silicon microstrip detectors planned for the ID and new readout for the LAr detector may be able to substantially reduce the power consumption of their analogue front-end circuits with these new SiGe technologies. The R&D program will include: a. Evaluate the radiation hardness of several SiGe technologies and from more than one vendor. b. Determine which, if any, technologies will meet the radiation requirements for the ATLAS Upgrade. Design a demonstration circuit for the front-end analogue readout of a silicon microstrip detector and the LAr detector in order to determine the expected noise and timing performance and the expected power consumption of these technologies. The goal of the program is to determine if some SiGe technologies can be useful for some applications in the upgraded ATLAS detector and to compare such technologies with other potential ones, for example a completely CMOS front-end circuit. MPI/Munich 12 February 2009

Technology selection At the time the proposal was made, the following potential foundries were identified: IBM (3 generations available) IHP AMS STm Motorola JAZZ It was initially intended to look at several technologies to sample a cross section what was available. Early radiation tests of IBM 5HP by UCSC Radiation tests of IHP (SG25H1, SG25H3, SGb25VD) by Barcelona A test chip on IHP-SG25H1 by UCSC Continuing work by IN2P3 with AMS Given the Frame Contract with IBM, the effort was focused on the available IBM technologies. MPI/Munich 12 February 2009

Promising results on “old” technologies Parts from the IBM-5HP, IBM-7HP and the IHP-SG25H1, H3 & VD technologies have been irradiated and the results were previously reported at conferences MPI/Munich 12 February 2009

On going radiation studies Based upon the availability of the IBM technologies through CERN and the preference for being compatible with 130 nm CMOS, the collaboration focused lately on the IBM-8HP and the IBM-8WL technologies. 8WL - a less expensive version of the 8HP and possibly more compatible with the 8RF The electrical characteristics of the 8WL appear to be quite adequate for ATLAS needs. The IBM-8HP was irradiated with protons at the CERN PS, gammas at the BNL cobalt source and neutrons at the Ljubljana reactor. Tests on 8WL structures is on going and data are discussed in the SiGe group 8WL parts were irradiated with gammas at BNL and neutrons at Ljubljana and Lowell (US). MPI/Munich 12 February 2009

Gummel-Poon Plots Show Typical Damage Gamma, neutron and proton irradiations show increased base leakage current. The increased base current lowers the DC gain, which is the one of the most important consequences of radiation damage. MPI/Munich 12 February 2009 12

Figures of Merit The DC current gain after radiation varies considerably with bias current. Based upon circuit design studies like ones already presented, we have established a nominal bias current density of 16 A/m2, i.e. a current density at which most circuits will be biased and at which we want a minimum gain to be held. Small size transistors can operate at lower bias while larger ones like those used for the first stage amplifier will need more bias. We also established a “figure of merit” of 50 for the desired minimum gain. The circuits can operate with less but this is our target for these studies. While several electrical characteristics were measured pre and post irradiation (e.g. forward Gummel-Poon, reverse Gummel-Poon, Early voltage, etc.), we will focus on the change in DC current gain (beta) for this presentation. MPI/Munich 12 February 2009 13

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The data in the following slides are from Alex Grillo presentation at CERN on June, 3rd, 2008. MPI/Munich 12 February 2009

8HP Neutron Irradiation The vertical line marks the nominal bias current density. The gain doesn’t scale with Jc as well as we have seen with other old bipolar technologies. The variations are not chip-to-chip as each figure contains data from only one chip array of transistors. Parts up to target fluence hold up well. MPI/Munich 12 February 2009

Effects of Thermal Neutrons Some parts with irradiated with a cadmium shield to filter out thermal neutrons. The parts don’t seem to show a large sensitivity to the thermal neutrons. The difference with and without the shield is not larger than the inherent variations. MPI/Munich 12 February 2009

8HP Gamma Irradiation The parts behave very well up to 50 Mrad. Also, the gains scale with Jc much better than for the neutron data. At 100 Mrad, the performance becomes very weak, but we are not sure if this is real. (See next slide.) In any case 100 Mrad is well beyond our target. MPI/Munich 12 February 2009

8HP Gamma Biased vs. Unbiased The 50 Mrad biased parts are slightly less damaged than the parts grounded during irradiation as we would expect. However, the 100 Mrad grounded parts behave much better than the biased ones leading us to believe something strange happened during the 100 Mrad biased irradiation. MPI/Munich 12 February 2009

8HP Proton Irradiation The bottom two plots look very marginal. The 3x1015 data probably does not meet our target but it exceeds our target fluence. This proton irradiation, however, had many problems. The PS broke down several times requiring the parts to be stored and then re- installed in the beam line. MPI/Munich 12 February 2009

8HP Proton Biased vs. Unbiased Again comparing biased to unbiased, the 3x1015 biased parts show a little less damage as expected. However, the 6.8x1014 biased parts a little worse than the unbiased ones adding to our concern that something odd happened during these long, multiple start proton irradiations at the PS. The 8HP proton irradiation would have to be redone before making any conclusions. MPI/Munich 12 February 2009

8WL Neutron Irradiation @ Ljubljana Here are three plots of three different 8WL transistor types: HP, MB, HB. The different letters are different transistors of different size on each chip. We have irradiated parts to three other fluences but they have not been measured yet. This data point is closest to our target fluence. MPI/Munich 12 February 2009

8WL Neutron Irradiation @ Lowell Here are measurements of some parts irradiated with neutrons at the Lowell facility (US). There parts show more damage at 6x1014 than those irradiated at Ljubljana. We have not used this facility before and these measurements became available just last Friday. (Different backgrounds?) More work is needed to understand the differences between the two sets of neutron data. MPI/Munich 12 February 2009

8WL Gamma Irradiation - First Look 8WL parts were (are being) irradiated with gammas at BNL to doses of 1, 10, 25 and 50 Mrad. Here is a first look at some of the data. MPI/Munich 12 February 2009

Preliminary conclusions A lot of data have been collected; some are still coming in; not all are analyzed. Both the 8HP and the 8WL appear to meet the radiation tolerance requirements for LAr and probably the long-strip silicon tracker. For the short-strip silicon tracker, it is not so clear. The remainder of the data must be analyzed and possibly more irradiations performed to answer some of the questions. MPI/Munich 12 February 2009

Possible Applications The collaborators on this SiGe evaluation come from the ATLAS silicon strip tracker community and the LAr community. The font-end amplifer-shaper-comparator for the silicon tracker The front-end amplifier-shaper for LAr The front-end board ADC for LAr (?) An IC submission “submitted” in Nov. 2008 with the 8WL technology. The submission includes a silicon tracker front-end circuit, a LAr front-end circuit and an array of test structures. MPI/Munich 12 February 2009

From Mitch presentation (Nov. 2008) MPI/Munich 12 February 2009

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Transmission line terminating preamplifier (Hybrid circuit adopted by ATLAS LAr) Input stage with bipolar transistors  it can be easily extended to SiGe. The “local feedback” gives low noise (Rnoise = 10 W) and badwidth with low power (50 mW) and good linearity Three “different” (Zin e Imax) hybrids:imply changing the values of three components but IDENTICAL CIRCUIT With CD = 330 pF, and 16 nsec 50 W line <tpeak>= 47.2 ns, rms = 0.3 ns ENI= 49.3 nA, rms = 0.53 nA MPI/Munich 12 February 2009

From Mitch presentation (Nov. 2008) MPI/Munich 12 February 2009

Technology comparison geared to RF MPI/Munich 12 February 2009

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From Philippe presentation (Nov. 2008) MPI/Munich 12 February 2009

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Technology comparison geared to RF MPI/Munich 12 February 2009

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SiGe is more expensive than CMOS, BUT less expensive than GaAs: this is the real advantage in RF industry. MPI/Munich 12 February 2009

In our field ….. The price is not our only concern Moreover all the components models are well suited for RF application, less importance is given to low frequency behavior. We need noise info We need “ad hoc” library The information about SiGe at cryogenics temperatures are old Besides it is not clear that devices “optimized” for speed ad room temperature can operate effectively at LAr temperature MPI/Munich 12 February 2009

SiGe Cressler Book MPI/Munich 12 February 2009