Effective Kinetic Variations with Stress Duration for Multilayered Metallizations

Ondrusek,; Nishimura,; Hoang,; Sugiura,; Blumenthal,; Kitagawa,; McPherson,

doi:10.1109/irps.1988.362219

Cited by 5 publications

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“…[4] and attributed to the high temperature due to jouleheating in the barrier metal. 5% to 30% (x%) resistance increase instead of open failure has been used as the metallization failure criterion [4][5][6][7]. The activation energy of the lifetime has been found to decrease with increasing x [5].…”

Section: Introductionmentioning

confidence: 99%

“…5% to 30% (x%) resistance increase instead of open failure has been used as the metallization failure criterion [4][5][6][7]. The activation energy of the lifetime has been found to decrease with increasing x [5]. The line-length and width dependencies of electromigration lifetime of multilayered structure were also found to depend on 0-7803-2031-X1951$4.00 Q 1995 IEEE 37 1 10008, TiN thin frlm was deposited by reactive sputtering onto (100)-Si wafer covered with 400A thermally grown SO2.…”

Section: Introductionmentioning

confidence: 99%

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Modeling electromigration failures in TiN/Al-alloy/TiN interconnects and TiN thin films

Jiang¹,

Cheung²,

Hu³

1995

33rd IEEE International Reliability Physics Symposium

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Electromigration characteristics, especially resistance oscillations, of TiN/Al-alloy/?" multilayered interconnect and failure mechanism of TiN barrier layer have been studied. A model has been developed for the line-width dependence of the multilayered structure. The experimental results show that the failure observed in TiN was not caused by electromigration, instead it was due to thermomigration caused by temperature gradient. The activation energy of this process was found to be 1.5eV. In order to obtain 10-year lifetime, the hottest spot in TiN film must be kept below 408°C. This suggests that TiN may safely conduct 2.4x107A/cm2 for typical thermal impedance of a hot spot.the resistance failure criterion[b-71. In order to stimulate electromigration reliability in circuit designs, there is a strong need to model the linelength and width dependencies of lifetime. At the same time, as the barrier layer is much thinner than that of Al-alloy layer, the current density at llocal gaps in TiN may be 10 times larger than the intended current density in Al layer. Also the TiN may be the only conductor at vialcontact sidewalls in some technologies. Therefore, resistance rise in the barrier layer material itself is of interest. The purpose of this study is to investjgate electromigration performances of TiN/Al-alloy/TiN multilayered structures and the reliability of TiN barrier layer material and to study the line-width and length dependencies of electromigration lifetime. EXPERIMENT

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Modeling electromigration failures in TiN/Al-alloy/TiN interconnects and TiN thin films

Jiang¹,

Cheung²,

Hu³

1995

33rd IEEE International Reliability Physics Symposium

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“…Interconnects made from A1 alloy thin films sandwiched between refractory metal thin films, typically fail during electromigration due to an increase in resistance (1). However, intralevel and interlevel shorts due to extrusions have also been reported (2) and the type of refractory metal underlying the Aluminum has been shown to play a major role (3).…”

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confidence: 99%

Change of the failure mode of layered aluminum conductors by modification of overlying dielectric

Pramanik

Chowdhury

Jain

1994

Proceedings of 1994 IEEE International Reliability Physics Symposium RELPHY-94

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The failure mode of multilayered A1 interconnects changes from shorts due to extrusions to failures due to resistance increase when the overlying dielectric is modified. A thick rigid dielectric favors failures due to exuusions whereas a more flexible dielectric favors resistance increase. The dielectric effectively changes the mechanical behavior of the interconnect without changing the overall kinetics of mass accumulation and depletion and suggests a model where the final mode of failure is determined by the response of the interconnect to mechanical stresses.Interconnects made from A1 alloy thin films sandwiched between refractory metal thin films, typically fail during electromigration due to an increase in resistance (1). However, intralevel and interlevel shorts due to extrusions have also been reported (2) and the type of refractory metal underlying the Aluminum has been shown to play a major role (3). In previous reports the underlying factors that determine the dominant mode of failure, resistance increase or shorts, have not been clearly elucidated. In this paper we show that the mode of failure of the metallization can be changed by modifying the overlying dielectric film, through two different intermetal oxide processes, both of which are widely used in the industry. The results provide a basis for a model that can be used to predict the mode of failures for other situations and allow a reliable metallization scheme to be designed. Exoerimental detailsThe electromigration studies were carried out on interconnects, consisting of a multilayer stack 200nmTiW/400nm All%Cu/"OnmTiW that formed metal 2 of a 0.61 triple level metallization scheme. Wafers with the metal 2 lines fabricated at the same time were split between two intermetal oxides (IMO) A and B, depicted in fig 1. IMO A was formed by an "etchback" process. In this process 0.61 PECVD oxide was deposited, 300nm of a siloxane spin on glass (SOG) was spun on and the SOG together with any exposed PECVD etched back Approximately, 0.31 of oxide was left on top of an isolated metal line leaving S O G only in small pockets between lines. 0 . 4~ of PECVD oxide was then deposited on top. IMO B was formed by a "non etchback" process. This consisted of depositing 0.251 of PECVD oxide, spinning 300nm of the SOG and depositing 0 . 4~ of PECVD oxide directly on the SOG. Metal lines 2 . 4~ and 1 . 0~ wide and 2.4mm long were stressed at 200°C with a current density of 3 MA/cm2. A comb structure with a spacing of 0.71.1 to the stressed line (SL) was used to monitor extrusions through an extrusion monitor line (EML). Electromigration test circuit schematic is shown in fig 2. A lOKR resistance was kept in series with the extrusion monitor line to limit the maximum current to be drawn by the monitor the moment an extrusion connected it to the stressed line. Thus, the current through the stressed line would remain the same even after a single extrusion was formed. The resistance of the metal line as well as the monitor line was measured and stored as a function of t...

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SAW resonators using epitaxially grown Al electrodes

Ieki

Sakurai

1993

Electron Comm Jpn Pt III

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Stress migration (SM) has become a serious issue with the development of surface acoustic wave (SAW) devices for high‐frequency application. For the first time, this paper discusses epitaxially grown Al electrode films as a countermeasure to SM. It also discusses a method of epitaxial growth of Al electrode films for an SAW resonator deposited onto quartz substrates. It is found that an epitaxially grown film has been fabricated under relatively moderate deposition conditions in vacuum evaporation. The orientation relation for this epitaxial growth is (311) «233»Al//(032)«100»SiO2. The SM lifetime for the SAW resonator thus obtained is found to be more than 2000 times longer and the allowable power value is improved by one order of magnitude more than that usually obtained for polycrystalline Al films with Cu. A discussion of the epitaxial growth mode and lifetime of electromigration also is presented.

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Effective Kinetic Variations with Stress Duration for Multilayered Metallizations

Cited by 5 publications

References 0 publications

Modeling electromigration failures in TiN/Al-alloy/TiN interconnects and TiN thin films

Modeling electromigration failures in TiN/Al-alloy/TiN interconnects and TiN thin films

Change of the failure mode of layered aluminum conductors by modification of overlying dielectric

SAW resonators using epitaxially grown Al electrodes

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