Dielectric Passivation and Geometry Effects on the Electromigration Characteristics in Al-1%Si Thin Film Interconnections

  • Kim, Jin-Young (Department of Semiconductor and New Materials Engineering, Kwangwoon University)
  • Published : 2001.07.01


Dielectric passivation effects on the EM(electromigration) have been a great interest with recent ULSI and multilevel structure tends in thin film interconnections of a microelectronic device. SiO$_2$, PSG(phosphosilicate glass), and Si$_3$N$_4$ passivation materials effects on the EM resistance were investigated by utilizing widely used Al-1%Si thin film interconnections. A standard photolithography process was applied for the fabrication of 0.7㎛ thick 3㎛ wide, and 200㎛ ~1600㎛ long Al-1%Si EM test patterns. SiO$_2$, PSG, and Si$_3$N$_4$ dielectric passivation with the thickness of 300 nm were singly deposited onto the Al-1%Si thin film interconnections by using an APCVD(atmospheric pressure chemical vapor deposition) and a PECVD(plasma enhanced chemical vapor deposition) in order to investigate the passivation materials effects on the EM characteristics. EM tests were performed at the direct current densities of 3.2 $\times$ 10$\^$6/∼4.5 $\times$ 10$\^$6/ A/cm$^2$ and at the temperatures of 180 $\^{C}$, 210$\^{C}$, 240$\^{C}$, and 270$\^{C}$ for measuring the activation energies(Q) and for accelerated test conditions. Activation energies were calculated from the measured MTF(mean-time-to-failure) values. The calculated activation energies for the electromigration were 0.44 eV, 0.45 eV, and 0.50 eV, and 0.66 eV for the case of nonpassivated-, Si$_3$N$_4$passivated-, PSG passivated-, and SiO$_2$ passivated Al-1%Si thin film interconnections, respectively. Thus SiO$_2$ passivation showed the best characteristics on the EM resistance followed by the order of PSG, Si$_3$N$_4$ and nonpassivation. It is believed that the passivation sequences as well as the passivation materials also influence on the EM characteristics in multilevel passivation structures.