Formation of vertical links in standard CMOS double-level metallizations by application of Nd:YAG- and excimer-laser radiation

• Main Authors: Hartmann, H.-D., Hillmann-Ruge, T.
• Format: Conference Proceeding
• Language: English
• Subjects: Fuses; Laboratories; Logic testing; Metallization; Optical design; Optical pulses; Redundancy; Statistics; System testing; Timing
• DOI: 10.1109/VMIC.1991.152983

Laser processing of vertical links has been studied on three different layer sequences with main emphasis on statistics. Experiments were carried out with a Nd:YAG and an excimer laser using a fixed number of pulses adapted to the layer sequence. Laser antifuses of different design and sizes were fabricated. Simple expanded interconnections of dimensions 10*10 mu m/sup 2/ (10/sup 2/), 14/sup 2/ and 20/sup 2/ (sequence 1 and 2) and 9.6/sup 2/, 12.6/sup 2/ and 19.5/sup 2/ (sequence 3) turned out to be best suitable. Applying two Nd:YAG pulses, maximum yield of 100% was obtained from 14/sup 2/ and 20/sup 2/-structures with low mean resistances R/sub m/ of 0.18 and 0.104 Omega , and a standard deviation sigma /sub R/ of 0.145 and 0.06 Omega respectively. Yield obtained from 19.5/sup 2/ was 100% with R/sub m/=0.219, and sigma /sub R/=0.199 Omega using 3 pulses and two contacts per structure. By application of two excimer pulses, maximum yield of sequence 2 was 100% obtained from 14/sup 2/- and 20/sup 2/-structures with R/sub m/=0.125 Omega and 0.163 Omega and a sigma /sub R/ of 0.095 and 0.12 Omega respectively. Application of three excimer pulses on 12.6/sup 2/-structures lead to a yield of 99.6% with R/sub m/=0.552 and sigma /sub R/=0.357 Omega . In all yield evaluations, resistances >or=3 Omega were treated as a failure.< >