Interconnect_Al

Interconnect_Al - Aluminum Interconnect Technology Outline...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
1 EE311 / Al Interconnects 1 tanford University araswat Outline Interconnect scaling issues Aluminum technology Copper technology Aluminum Interconnect Technology EE311 / Al Interconnects 2 tanford University Properties of Interconnect Materials Metals Silicides Barriers Material Thin film resistivity ( μ ! " cm ) Melting point (˚C) Cu 1.7-2.0 1084 Al 2.7-3.0 660 W 8-15 3410 PtSi 28-35 1229 TiSi 2 13-16 1540 WSi 2 30-70 2165 CoSi 2 15-20 1326 NiSi 14-20 992 TiN 50-150 ~2950 Ti 30 W 70 75-200 ~2200 N+ polysilicon 500-1000 1410
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 EE311 / Al Interconnects 3 tanford University araswat SILICIDES - Short local interconnections which have to be exposed to high temperatures and oxidizing ambients, e.g., polycide and salicide structures. REFRACTORY METALS – Via plugs, future gate electrodes, local interconnections which need very high electromigration resistance. TiN, TiW – Barriers, glue layers, anti re±ection coatings and short local interconnections. Al, Cu - for majority of the interconnects Interconnect Architecture Intermetal Dielectric First Level Dielectric Vias Contacts Local Interconects Global Interconects EE311 / Al Interconnects 4 tanford University Al has been used widely in the past and is still used Low resistivity Ease of deposition (melting pt. 660°C) Dry etching Does not contaminate Si Ohmic contacts to Si but problem with shallow junctions Excellent adhesion to dielectrics Problems with Al • Electromigration lower life time • Hillocks shorts between levels • Higher resistivity Why Aluminum?
Background image of page 2
3 EE311 / Al Interconnects 5 tanford University araswat Electromigration due to electron wind induced diffusion of Al through grain boundaries SEM of hillock and voids formation due to electromigration in an Al line Electromigration induced hillocks and voids void Hillock Void Metal Metal Dielectric Electromigration EE311 / Al Interconnects 6 tanford University F scat F field + E field F TOTAL = F SCAT + F FIELD " qz # ! E " D = μ ! # q ! * kT " D " ! E = J = ! E = ! E # D = D o e " E a kT D = J qZ * kT D 0 e $ E a kT MTF " e # E a kT MTF = A m J n e # E a kT Using Einstein’s relation current density is related to E field by Diffusivity is given by Therefore Meantime to failure is thus of the form of A phenomenological model for MTF is γ is the duty factor M, n are constants Electromigration Theory Where qz* is effective ion charge Small compared to F SCAT
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
4 EE311 / Al Interconnects 7 tanford University araswat 1/T Ln (MTF) MTF !
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 13

Interconnect_Al - Aluminum Interconnect Technology Outline...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online