Preparing Crystalline Porous Silica Low-k Thin Films by One Stage Hydrothermal Process in Base Environment
Date Issued
2009
Date
2009
Author(s)
Kung, Chien-Hao
Abstract
Low dielectric constant (low-k) material is important in semiconductor industry. Crystalline porous silica which is prepared by two stages hydrothermal process in base environment possesses advantages of low dielectric constant, good mechanical strength, and easily-preparation procedures. However traditional synthesis process is very tedious, and some procedures are not necessary actually. In the present study, an one stage hydrothermal method is used, and the effects of hydrothermal process and centrifugation on the properties of crystalline porous low-k silica thin film were examined.t was found that the size, concentration, and crystallinity of the particles are proportional to hydrothermal period. Also the particle size is less uniform than what is prepared by two stage process. After the reaction, the solution containing particles was centrifuged, and it showed that centrifugation process would influence the crystalline, concentration of particle and viscosity of solution. However, the followings were observed: First, longer hydrothermal time would result in higher porosity in thin film and more large voids from particles piled up each other which would result in serious leakage current and influence the measurement of k value. Second, the better crystalline of particles in the colloid would cause the mechanical strength poor, since pooler hydroxide groups on particle surface. Third, thicker thickness of film might result in the process of surface modification incomplete, and the dielectric constant couldn’t be decreased. Finally, the film derived from the solution taken from the upper side of centrifugation tube after centrifuged was used for the spin-coating on silicon wafer. The film possesses lower k value and leakage current density and higher mechanical strength than the film spun by the solution un-centrifuged.he processes applying surfactant and centrifugation both could not only decrease k value by increasing the total pore volume in the film, but also decrease quantity of large voids, and facilitate the coating situation on the surface.he best thin films prepared in this research possess the k value of 1.78~1.88, hardness of 1.33~1.46Pa, elastic modulus of 11.10~12.72Gpa, and leakage current of 1.37e-8~4.97e-8 A/cm2. The films were derived by taking the upper side solution of centrifugation tube after centrifuged, and the solution were synthesized under the hydrothermal conditions, temperature 100℃ for 36~42 hours.
Subjects
low dielectric constant
thin film
surfactant
zeolite
porous material
crystalline
centrifugation
base environment
one stage hydrothermal method
Type
thesis
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