Water Absorption and Densification of Phosphosilicate Glass Films

Abstract

The interaction between phosphosilicate glass films and water vapor has been studied at the temperature range 70–100°C, using infrared spectroscopy. The films were deposited at 640°C using low pressure chemical vapor deposition. The infrared spectra change significantly during the exposure of the films to water vapor. In spite of the observed decrease in the intensity of the P=O band it has been found that phosphorus ions do not outflow from glasses that contain less than 8 m/o phosphorus oxide. The diffusion of water in the films can be described by a single activation energy, which increases with increasing phosphorus oxide concentration. Densification of the glass by means of heat‐treatment substantially increases the film resistance to water absorption. The densification of the phosphosilicate glass has been studied by infrared spectroscopy and etch rate measurements. The efficiency of the densification increases with increasing the temperature and time of the heat‐treatment. The effectiveness of the ambients used in this study can be ranked in the order: normalsteam>O2>normalAr,N2 .

Water diffusion into silica glass at a low temperature under high water vapor pressure

“…Also, the rate of water penetration into silicate glasses is being used as a means to determine the age of both archaeological and geological glasses [1,2]. Water diffusion coefficient in silica glass is small at low temperature, but still it can influence surface-sensitive properties of bulk glass and properties of amorphous thin films [3][4][5] and porous materials. Thus, it is useful to determine the water diffusion coefficient in silica glass.…”

Influence of water absorption by silicate glass on the strains in passivated Al conductor lines

“…It is well known that the presence of water unfavorably influences the electrical characteristics of devices and accelerates corrosion of aluminum metallizations. 8 The present paper shows that substantial strain rearrangement can take place in passivated lines over long time periods. It can be expected that these processes affect the long-term reliability of devices.…”

“…[3][4][5][6][7][8][9][10][11][12][13][14] Films obtained by the oxidation of silicon at high temperatures (>1000°C) are quite stable and no time-dependent changes are observed at ordinary temperatures. 12,13 The situation is quite different for films used as passivation layers of a structure.…”

“…3,4,6,7,10,12 Instead, at temperatures below 400-500°C, a tensile stress component is superimposed on the thermal stress. Infrared spectroscopy has shown that water is absorbed in these films 5,6,8,10,14 and the tensile stress component arises from the desorption of water during heating. The process of water absorption is reversible; i.e., if the sample is exposed to a moist atmosphere after dehydration, a compressive stress component again develops.…”

“…Further heating above 500-600°C leads to a superposition of a compressive stress component that is caused by densification of the silicate glass. 3,7,8,10 The densification also leads to an increase in the resistance against water absorption, depending on the maximum annealing temperature 8 and deposition technique. 5 In the present study, x-ray diffraction was used to measure the room-temperature strains in aluminum conductor lines covered by a passivation layer of lowtemperature oxide (LTO).…”