The dependence of the electrical characteristics of hydrothermally crystallized pure-silica–zeolite films on the water concentration in the precursor was investigated. Zeolite was crystallized in a silica–zeolite composite film after spin-coating the precursor, which was composed of tetraethylorthosilicate, tetrabutylammonium hydroxide, ethylalcohol, and deionized (DI) water, followed by calcinations at 400 °C. The results of Fourier-transform infrared (FT-IR) spectroscopy indicated that the number of Si–OH and O–H bonds decreased with an increase in the water concentration in the precursor. The dielectric constant of the film decreased with an increase in water concentration, while the leakage current increased.

The dielectric constant, elastic modulus and reliability of the pure silica-zeolite composite film which was formed by self-assembly of porous silica having hydrothermally crystallized zeolite nanoparticles. Fourier-transform-infrared spectroscopy indicated that Si-OH and O-H bonds decreased by zeolite formation, resulting in the decrease of the dielectric constant. Silylation hardening by 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS) vapor treatment could decrease the dielectric constant due to the decrease of Si-OH and O-H bonds. The elastic modulus of 7.03 GPa and the dielectric constant of 1.94 were achieved for the meso-porous silica-zeolite film by silylation hardening. Furthermore, mean-time-to-failure (MTF) lifetime of time-dependent dielectric breakdown (TDDB) is longer than ten years at 125 C under the electric field of 3.4 MV=cm.With scaling down of semiconductor device dimensions, a signal delay time has increased due to the increase of interconnect resistance and parasitic capacitance. 1 In order to overcome this problem, low dielectric constant (low-k) interlayer dielectric films are needed. A lower dielectric constant can lead to lower power dissipation and less interline crosstalk as well as lower RC delay. The porous silica which is the composite of silica and pores has been investigated as a possible candidate of ultra low-k films. 2 However, the mechanical strength of the porous silica was degraded because the elastic modulus decreased due to its pore structure. 3 The mechanical properties of the low-k films are of great importance because the films must withstand the stresses developed during the packaging process and chemical mechanical polishing (CMP) in integrated circuits chip fabrication process. Therefore, control of the skeletal silica structure in terms of elastic modulus is important.Recently, nanostructured zeolite films have been studied and demonstrated to be a promising low-k material. The young's modulus of the zeolite is 110 GPa, 4 which is larger than that of SiO 2 (73 GPa). The high porosity of the zeolite films can maintain comparatively higher mechanical strength than amorphous porous silica. Furthermore, it has the better thermal conductivity and hydrophobicity than SiO 2 . 5À10 The mobil eleven (MEL) type zeolite was adopted in this work, whose pore diameters are 0.53 and 0.54 nm in the silica skelton. 11,12 In this paper, effects of zeolite crystal formation processes on the film properties of pure silica zeolite films are investigated. ExperimentalThe pure silica MEL zeolite was prepared by hydrothermal crystallization. The film was formed by a spin on process of zeolite nanoparticle suspension. The preparation of the zeolite films had two steps. One was synthesis of the zeolite nanoparticle suspension and the other was spin coating of the suspension onto Si wafer.The process flow is shown in Fig. 1. A few nm thick native oxide was formed on the surface of Si wafer. Tetrabutylammonium hydroside (TBAOH) was mixed with ethylalcohol (EtOH), tetraethylorthosilicate (TEOS), a...

A pure silica zeolite film was formed by use of hydrothermally crystallized zeolite nanoparticles in a porous silica precursor. The effects of silylation hardening by tetramethylcyclotetrasiloxane ͑TMCTS͒ vapor treatment on the electrical characteristics of pure silica zeolite films were investigated. The results from Fourier-transform-IR spectroscopy indicated that the O-H bond decreased by zeolite formation, resulting in the decrease of the leakage current by 1/10. Silylation hardening by TMCTS vapor treatment could reduce the leakage current by 4 orders of magnitude due to the reduction of Si-OH and O-H bonds. The elastic modulus of 5.18 GPa and the dielectric constant of 1.96 were achieved simultaneously by silylation hardening. Consequently, the electrical and mechanical characteristics of the pure silica zeolite film as well as the time dependent dielectric breakdown lifetime were improved.With the shrinking of interconnect feature sizes of silicon ultralarge-scale integrated circuits, 1 the signal delay time increases due to the increase of interconnect resistance and parasitic capacitance. To overcome this problem, low-dielectric-constant interlayer dielectric films are needed. Mesoporous silica with pore sizes ranging from 2 to 50 nm have been studied as a potential candidate for ultralow-k materials. 2 However, the mechanical strength of the low-k film is degraded when mesopores are introduced into the skeletal materials to reduce the film density. Chemical mechanical polishing may cause damage to the porous low-k material. Moreover, it is known that the low-k film to which mechanical strength is weak receives damage in the packaging, so both low-k and high mechanical strength are required. Pure silica zeolite is a promising candidate as an advanced low-k material. 3,4 The Young's modulus of the zeolite is 110 GPa, 3 which is larger than that of SiO 2 ͑73 GPa͒. This is because the silica network in the zeolite has a three-dimensional crystal structure. The zeolite also has low-k because the film density is lower than that of quartz due to the micropores in the crystalline silica. It has a higher elastic modulus, thermal conductivity, and hydrophobicity than SiO 2 . 4-10 The mobile 11 ͑MEL͒-type zeolite was adopted in this work. 11,12 The zeolite was made by a hydrothermal crystallization method. MEL-type zeolite has a 10-membered ring with pore diameters of 0.53 and 0.54 nm as shown in Fig. 1. In this paper, the effects of silylation on the film properties of pure silica zeolite dielectric films are investigated. ExperimentalThe formation process of MEL-type zeolite is shown in Fig. 2. A few nanometers thick native oxide was formed on the surface of Si wafer. First, the precursor solution of tetrabutyl ammonium hydroxide ͑TBAOH͒, tetraethyl orthosilicate ͑TEOS͒, and ethyl alcohol ͑EtOH͒ were mixed and stirred for 24 h at room temperature. Hydrolysis of TEOS was caused by EtOH. TBAOH was purified by filtering with the ion exchange resin. Both TEOS and EtOH were of semiconductor grade. The hydrothermal cr...

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