Copper diffusion barrier properties of CVD boron carbo-nitride

Abstract

The copper diffusion barrier properties of amorphous boron carbo-nitride ͑BC x N y ͒ films were studied. The BC x N y films were deposited by chemical vapor deposition at 360°C and 1 Torr using dimethylamine borane with no reaction gas ͑BC 0.37 N 0.15 ͒, with NH 3 ͑BC 0.19 N 0.44 ͒, or with C 2 H 4 ͑BC 0.90 N 0.08 ͒; their dielectric constants were 4.1, 4.4, and 3.9, respectively. A SiC 0.76 N 0.44 film was used to benchmark the study. Barrier films were deposited on 7 nm thermal oxide/ n-type Si substrates. The leakage current for BC 0.90 N 0.08 , 1.1ϫ 10 −8 A/cm 2 at 0.5 MV/ cm, is the lowest of the three but it is larger than that of the benchmark SiC 0.76 N 0.44 film, 5.5ϫ 10 −9 A/cm 2 . Time dependent dielectric breakdown is used to test barrier time-to-failure of Cu-gate capacitors at 150°C and +2 to 5 MV/ cm. BC 0.90 N 0.80 displayed barrier performance comparable to SiC 0.76 N 0.44 and was noticeably better than BC 0.37 N 0.15 and BC 0.19 N 0.44 . Overall, BC x N y barriers are promising and are improved with lower boron content, fewer B-B bonds, and increased B-C bonds.

Dielectric Barrier, Etch Stop, and Metal Capping Materials for State of the Art and beyond Metal Interconnects

“…434,439 Related CVD a-BCN:H films have been reported to have slightly lower k values of 3.7-4.6 with similar mass densities. 444,445 These films have exhibited good adhesion strengths to Cu and low-k a-SiOC:H ILDs 445 and similar TDDB lifetimes to a-SiCN:H in Cu gated metal-insulator-semiconductor (MIS) capacitor devices. 446 From a DB perspective, CVD a-BCN:H films as thin as 4 nm have been demonstrated as porous ILD pore sealants, 447 and as a Ge passivation and surface oxidation diffusion barrier.…”

“…444,445 These films have exhibited good adhesion strengths to Cu and low-k a-SiOC:H ILDs 445 and similar TDDB lifetimes to a-SiCN:H in Cu gated metal-insulator-semiconductor (MIS) capacitor devices. 446 From a DB perspective, CVD a-BCN:H films as thin as 4 nm have been demonstrated as porous ILD pore sealants, 447 and as a Ge passivation and surface oxidation diffusion barrier. 448 Even lower k values of 1.9-2.2 have been reported for some PECVD a-BCN:H films where the ability to impede Cu diffusion has also been demonstrated.…”

Integration of Low‐ k Dielectric Films in Damascene Processes

“…These fi lms necessitated the development of new precursors, such as tetramethylsilane (4MS) and trimethylsilane (3MS), which have replaced the standard silane (SiH 4 ). In addition, boron-based fi lms are suggested as potential alternatives to the silicon-based diffusion barriers [61,62].…”

Electrical characteristics of thin boron carbonitride films on Ge(100) and Si(100)

“…BC x N y films deposited by chemical vapor deposition ͑CVD͒ in our laboratory have tunable dielectric constants ͑3.7Ͻ Ͻ 4.6͒ and stoichiometry ͑0.05Յ x Յ 1.51, 0.05Յ y Յ 0.67͒. 29 Two prior BC x N y ͑henceforth referred to a͒ Present address: Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309. b͒ Author to whom correspondence should be addressed; electronic mail: ekerdt@che.utexas.edu as BCN for simplicity͒ passivation studies in our laboratory revealed that when BCN is ϳ4 nm it should be sufficiently thick to achieve continuous coverage of a Ge͑100͒ substrate 30 and prevent oxidation of the Ge both in ambient and during a 250°C atomic layer deposition ͑ALD͒ HfO 2 process.…”