Barrier characteristics of chemical vapor deposited amorphous-like tungsten silicide with in situ nitrogen plasma treatment

• Published in: Journal of the Electrochemical Society 1999-07, Vol.146 (7), p.2533-2539
• Main Authors: CHANG, Kow-Ming, DENG, I-Chung, YEH, Ta-Hsun, SHIH, Chien-Wen
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Diodes; Electronics; Exact sciences and technology; Junction diodes; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1.1391967

Our team investigated the characteristics of inserting an 80 nm amorphous-like WSi sub 1.6 N sub 0.5 /WSi sub 1.6 barrier layer between aluminum film and a shallow diode to retard aluminum and silicon interdiffusion. In one chamber without breaking vacuum, we used a nitrogen plasma treatment to stuff nitrogen atoms into the grain boundaries of amorphous-like tungsten silicide film. The nitrogen atoms eliminated the fast diffusion paths of film, thus giving the amorphous-like tungsten silicide film a smaller diffusion coefficient. We then examined the failure of diodes with amorphous-like WSi sub 1.6 N sub 0.5 /WSi sub 1.6 barriers which were annealed at 575 deg C for 30 min and which had leakage currents of 10 exp 7 and 10 exp 8 nA/cm exp 2 . These diodes failed due to the diffusion of aluminum along the sidewalls of the barriers and the field oxide interface. In the search for a solution to this problem we investigated the use of tetraethylorthosilicate, which is known for its thermal stability as a stress buffer. In this experiment we used tetraethylorthosilicate to form a 'contact array structure' which in turn prevented diode failure at 575 deg C annealing for 30 min, and furthermore, the diodes in the contact array structure only began to show evidence of degradation at 600 deg C.