Moisture-induced capacitance-voltage instabilities in mesoporous silica thin films

Thin films of mesoporous silica (MPS) are attractive for low-permittivity interlayer isolation in integrated circuit wiring. Here, we report the mechanisms of moisture-induced capacitance-voltage (C-V) instabilities in MPS films. Upon annealing Al∕MPS∕Si(001)∕Al capacitors between 80 to 200 °C, the flat-band voltage first increases, reaches a maximum, and then decreases. Concurrently, the initially observed deep depletion behavior is replaced by strong inversion. Subsequent air exposure restores the preanneal C-V characteristics. Kinetics analyses reveal two thermally activated processes: Proton generation through fissure of silanol bonds (activation energy Ea1=0.42±0.04eV) and proton-induced depassivation of dangling bond traps (Ea2=0.54±0.05eV) at the MPS∕Si interface. We present an empirical model correlating these processes with the C-V characteristics. Our findings will be important considerations in designing processes for integrating MPS films into microdevices.

[1]  I. Mártil,et al.  Annealing effects on the interface and insulator properties of plasma-deposited Al/SiOxNyHz/Si devices , 2004 .

[2]  K. Chao,et al.  Microstructure and Mechanical Properties of Surfactant Templated Nanoporous Silica Thin Films: Effect of Methylsilylation , 2003 .

[3]  Karen Maex,et al.  Low dielectric constant materials for microelectronics , 2003 .

[4]  Ronald D. Schrimpf,et al.  Proton-induced defect generation at the Si-SiO/sub 2/ interface , 2001 .

[5]  R. Devine,et al.  Electric-field-induced transport of protons in amorphous SiO 2 , 2001 .

[6]  G. Ruan,et al.  Simulation of the dielectric constant of aerogels and estimation of their water content , 2000 .

[7]  M. Nogami,et al.  Proton Conduction in Porous Silica Glasses with High Water Content , 1998 .

[8]  M. Pejovic,et al.  Modelling of kinetics of creation and passivation of interface traps in metal-oxide-semiconductor transistors during postirradiation annealing , 1998 .

[9]  Shyam P. Murarka,et al.  Multilevel interconnections for ULSI and GSI era , 1997 .

[10]  M. Nogami,et al.  Evidence of water-cooperative proton conduction in silica glasses , 1997 .

[11]  Minoru Tomozawa,et al.  An infrared spectroscopic study of water-related species in silica glasses , 1996 .

[12]  Minoru Tomozawa,et al.  Water diffusion into silica glass: Structural changes in silica glass and their effect on water solubility and diffusivity☆ , 1995 .

[13]  Brauer,et al.  Lifetime broadening in bulk photoemission spectroscopy. , 1993, Physical review. B, Condensed matter.

[14]  H. Tompkins,et al.  Kinetics and mechanism for desorption of H2O from spin‐on‐glass , 1993 .

[15]  J.R. Schwank,et al.  Latent thermally activated interface-trap generation in MOS devices , 1992, IEEE Electron Device Letters.

[16]  M. Németh-Sallay,et al.  Charge motion in silicon MOS structures , 1980 .

[17]  H. Grubin.  The physics of semiconductor devices , 1979, IEEE Journal of Quantum Electronics.

[18]  R. Iler.  The Chemistry of Silica: Solubility, Polymerization, Colloid and Surface Properties and Biochemistry of Silica , 1979 .