Suppression of migration in Al conductors by lowering deposition temperature in plasma CVD SiN passivation

Storage tests at elevated temperatures and electromigration tests were performed on aluminum (Al) conductors covered with silicon nitride passivation deposited at low temperature by plasma enhanced chemical vapor deposition (CVD). It was shown that the migration such as stress induced voiding and electromigration can be reduced by lowering the deposition temperature of the passivation layer. The discontinuity failure by voiding is reduced and leads to increased lifetimes. The generation of notchlike voiding is also reduced. Improvements were attributed to the reduction of thermally induced stress in Al conductors at test temperatures. The plasma silicon nitride passivation deposited at low temperature was preferable as a candidate for passivation layers in devices with submicron Al conductors.<>