On the Issue of Crack Formation in a Thin Dielectric Layer on Silicon under Thermal Shock
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JMEPEG https://doi.org/10.1007/s11665-020-04925-4
On the Issue of Crack Formation in a Thin Dielectric Layer on Silicon under Thermal Shock Arkadiy A. Skvortsov, Marina V. Koryachko, Pavel A. Skvortsov, and Mikhail N. Lukyanov (Submitted May 19, 2020) The work is devoted to the problem of crack formation in thin sublayers of silicon oxide during pulsed heating of interconnects on single-crystal silicon wafers. It was shown that the passage of current pulses with an amplitude of up to 8 3 1010 A/m2 and a duration of up to 500 ls leads to thermal destruction of the interconnects and contributes to the formation of microcracks in SiO2 films along the metallization path. The magnitude of the mechanical stresses arising in the structure during thermal shock is estimated. It is shown that in contrast to SiO2 films, the level of mechanical stresses in silicon is insufficient for cracking near the source of thermal shock. It was also found that the nature of cracking in a dielectric film depends on the quality of the deposition of the dielectric film and the metal film, as well as the state of the dielectricmetal interface. Keywords
dielectric film, energy approach, heat equation, micro-electro-mechanical system
1. Introduction It is well-known that in modern micro- and nanoelectronics thin-film structures are actively used as a gate dielectric, passivating layers, membranes, etc. (Ref 1, 2). For example, films of thermal silicon oxide are used for static balancing of elements of micro-electro-mechanical systems (MEMS). This is achieved using residual stresses arising at the boundary of thermal silicon oxide–silicon (SiO2-Si) (Ref 3). Using MEMS elements so balanced, new designs can be created in microrobotics. In addition, thin films of silicon oxide are actively used as membranes in optical filters. At the same time, thermal effects during technological operations can lead to the appearance of tensile stresses from 100 to 300 MPa in them. It was also found that the coefficient of thermal expansion and residual stresses in thin films vary depending on the film thickness (Ref 4). Traditionally, thin dielectric films are also used as an insulating dielectric. High current densities can cause rapid amorphization and help maintain film integrity. However, an excess of electric powers above critical values leads to the films destruction. It was found that cracking in the film is one of the main reasons for the decrease in its electric capacitance (Ref 5). Moreover, high thermal loads on the film can lead to the Arkadiy A. Skvortsov and Mikhail N. Lukyanov, Department of Mechanics of Materials, Moscow Polytechnic University, 38 Bolshaya Semenovskaya Str, Moscow, Russian Federation 107023; Marina V. Koryachko, Department of Physics, Moscow Polytechnic University, 38 Bolshaya Semenovskaya Str, Moscow, Russian Federation 107023; and Pavel A. Skvortsov, Laboratory of Modeling, Mechanical Engineering Research Institute, Russian Academy of Sciences, 4 Maly Kharitonyevsky Lane, Moscow, Russian Federation 101000. Contact e-mail: skvortsov5505@ubogaz
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