Moisture Uptake and Outgassing in Patterned and Capped Porous Low-k Dielectric Films

Abstract

The interactions of moisture with spin-on porous methylsilsesquioxane ͑p-MSQ͒ low-k dielectric films are investigated by on-line and real-time measurement of the rates of moisture uptake and removal. A process model is developed that provides information on the dynamics of moisture adsorption and desorption processes. The process model can be used to find optimum purge temperature and gas purity condition for cleaning and drying of low-k films. The cured p-MSQ films are compared with the partially etched and N 2 H 2 ashed films. The results show that these two films have similar moisture solubilities; however, the moisture diffusivity in the patterned film is considerably higher. Transmission electron microscope results show that the etching and ashing processes not only decrease the overall film thickness but also increase the film porosity. The process model also provides information on moisture distribution within the film; this information is important in characterizing residual moisture and interfacial adhesion. The results for a wide range of diffusivity show that thin cap layers with low moisture solubility effectively block moisture penetration into the p-MSQ film without slowing down the outgassing and moisture removal during the purge.

Effect of Sampling Line Characteristics on the Dynamic Monitoring of Fluid Concentrations

“…In this case a model for a sample source system was available to determine the PoS and was linked with the sampling line model. The model for the source is that of a reactor containing samples of low- k dielectrics which are undergoing purge and outgassing; the detailed description of this reactor and its model is given in our earlier publications. ,, In Figure , the experimental results are at 25 °C for the EIMS analyzer setup, as shown in Figure . The input for the system was a step down function.…”

“…The signal will be changed in the sampling line as the sample is sent from the PoS to the PoA. Figure shows the actual experimental setup; the details are given in our earlier publications. ,, The model impurity compound used in this study was moisture; the inert purge gas was nitrogen; the experiments were performed using moisture concentration from 0.5 to 1500 parts per million (ppm) over temperatures ranging from room temperature to 380 °C. Some experiments were also performed with isopropyl alcohol (IPA) in a concentration range from 150 to 1500 ppm at room temperature.…”

Effect of water uptake on the fracture behavior of low-k organosilicate glass

“…To ensure comparison with previous work, the SiCOH films were exposed to a humid environment for water uptake after being pretreated by plasma exposure, which was done for demethylation/hypomethylation and to increase the number of hydrophilic groups (mainly, hydroxyl groups, -OH). The humidity exposure was done by exposing the samples to high moisture content air [about 80% relative humidity (RH)] at room temperature for 60 h. The exposure time was chosen based on the moisture absorption and desorption dynamics model of Yao et al, 19 to make sure the hydrophilic SiCOH film was water-saturated. Then, the hydrogenbonded (a-or b-bonded) water absorbed by the films was removed selectively by setting different annealing temperatures using a programmable annealing system (190 C annealing to remove a-bonded water and 400 C annealing to remove b-bonded water) as described previously.…”

“…22 Deconvolution analysis of the FTIR absorption spectrum assigned to the Si-O-Si skeleton, usually from 950 cm À1 to 1200 cm À1 , gives some insights of the states of different types of Si-O-Si bonds: Si-O-Si network ($1063 cm À1 ), Si-O-Si cage ($1130 cm À1 ), and Si-O-Si suboxide ($1023 cm À1 ). 19 The bond strength of the Si-O-Si bonds is severely weakened when the bond angle deviates from the mean value of 144 . 23 The annealing-induced residual stress, if any, can be produced by the different fractions of the networked structure, the cage structure and the suboxide structure.…”

“…Since both water solubility and diffusivity change due to UV-curing-induced structural rearrangements, the moisture intrusion and retention behavior is believed to be different from that of as-deposited samples. 19 Thus, it is also useful to determine the effects of UV curing on water-dependent film cracking thresholds. As depicted in Fig.…”