Title :
Electromigration characteristics of tungsten plug vias under pulse and bidirectional current stressing
Author :
Tao, Jiang ; Young, K.K. ; Pico, Carey A. ; Cheung, Nathan W. ; Hu, Chenming
Author_Institution :
Dept. of Electr. Eng. & Comput. Sci., California Univ., Berkeley, CA, USA
Abstract :
Using Kelvin test structures, electromigration performances of selective CVD tungsten filled vias under DC, pulsed DC, and AC current signals have been studied. The metallization consists of Al-Cu/TiW multilevel metals. The via electromigration lifetime exhibits a current polarity dependence. The via AC lifetimes are found to be much longer (more than 1000*) than DC lifetimes under the same peak stressing current density. The via lifetimes under pulsed DC stress of 50% duty factor are twice the DC lifetimes at low-frequency regions (<200 Hz) and 4-5 times the DC lifetimes at high-frequency regions (>10 kHz). The results are in agreement with the vacancy relation model.<>
Keywords :
CVD coatings; VLSI; electromigration; materials testing; metallisation; reliability; tungsten; AC lifetimes; AlCu-TiW metallisation; DC lifetimes; Kelvin test structures; W filled vias; W plug vias; bidirectional current stressing; current polarity dependence; electromigration characteristics; electromigration lifetime; electromigration performances; electromigration resistance; pulse current stressing; pulsed DC stress; selective CVD; stressing current density; vacancy relation model; via lifetimes; Aluminum; Circuit testing; Electromigration; Electrons; Integrated circuit interconnections; Kelvin; Metallization; Plugs; Sputter etching; Tungsten;
Journal_Title :
Electron Device Letters, IEEE
