Indentation-induced delamination of plasma-enhanced chemical vapor deposition silicon nitride film on gallium arsenide s
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Jin Zou Centre for Microscopy and Microanalysis, The University of Queensland, QLD 4072, Australia; and State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, Hunan, China
Yuehui He State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, Hunan, China (Received 23 October 2012; accepted 22 January 2013)
Nanoindentation was performed on amorphous silicon nitride films of different thicknesses deposited on gallium arsenide (GaAs) (001) substrates using a conical indenter. Both “pop-in” and ‘pop-out’ were observed from the load-displacement curves when the indentation load exceeded a critical value. Pop-in occurring during loading is associated with plane-slip in the GaAs substrate, and pop-out during unloading is attributed to the interfacial delamination between the film and the substrate. Finite element modeling (FEM) was used to analyze the stress evolution during unloading. The FEM results showed that the stress at the interface evolved from compressive to tensile status during the withdrawal of indentation load, and the interfacial debonding was induced at a critical tensile stress, which is consistent with the pop-out observed. A deformation model for interpreting the pop-in and pop-out events is thereby proposed.
I. INTRODUCTION
Gallium arsenide (GaAs) is a superior semiconductor to silicon for optoelectronic devices due to its ability to handle signals at higher frequencies, at the same time, generate lower noise.1,2 However, the application of GaAs is somewhat limited as surface contamination due to oxidation could deleteriously affect the performance of the optoelectronic devices.3 Therefore, surface passivation is critical for improving the reliability of GaAs-based semiconductor devices. Amorphous silicon nitride (SiNx) thin films are one of the most widely used materials for the passivation of GaAs.4 Besides surface passivation, a silicon nitride coating could also act as the dielectric film for metalinsulator-metal (MIM) capacitors in the fabrication of GaAs devices and circuits.5 For ensuring the reliability of GaAs-based electronic devices, a silicon nitride (SiN) film must adhere well to the substrate to prevent the underlying substrate material from being exposed to atmosphere.6 Any damage to the SiN film or debonding of the film from the GaAs substrate could lead to localized oxidation corrosion, which would subsequently cause failure of the passivation. During processing or service, stress being generated at the film/substrate interface may accelerate the detachment of the film from the substrate. Crack and delamination induced at high a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2013.31 J. Mater. Res., Vol. 28, No. 8, Apr 28, 2013
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stress locations would eventually result in the shorting of adjacent structures and electromigration of metals for the SiN/GaAs-based MIM capacitors.7 It is therefore important to understand the interfacial failure
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