Films In Microelectronic Devices Research Articles

Construction of porous poly (aryl sulfide sulfone) film with low dielectric constant and excellent mechanical property

AbstractThe low dielectric constant and excellent mechanical property polymer film plays important roles in the high‐speed integrated circuits. In this work, porous poly (aryl sulfide sulfone) (PASS) films with different pore regularities and distributions were systematically fabricated via a combination process with solvent evaporation, wet induced phase separation, and hot pressing. It is found that the macroporous structure of PASS films changed from irregular shape with large pore size distribution to regular shape with small pore size distribution and the sponge‐like pore structure disappeared then formed a dense layer by controlling the time of solvent evaporation and hot pressing, to realize the effective control of the pore structure. The optimal PASS porous film D3 which was heated for 25 min and then hot pressed for 4 min has a low dielectric constant (2.44) and dielectric loss (0.010), high tensile strength (62.14 MPa) and breakdown strength (139.32 kV/mm), and low water absorption (0.54%). The comprehensive excellent properties are beneficial to the application of PASS films in microelectronic devices.

Evolution free-boundary problem for a stationary system of the theory of elasticity

We consider an evolution free-boundary problem for a stationary linear system of the theory of elasticity encountered in the investigation of solid thin films in microelectronic devices. Its solvability is proved on an arbitrary time interval under the condition that the initial data are sufficiently close to the stationary solution.

Morphology and Dielectric Property of Cellular Polyimide Films Prepared by Phase Inversion

In order to explore low dielectric polymeric materials, two types of cellular polyimide films with different dianhydride units were prepared by phase inversion method, and their dielectric properties were investigated. Polyimide films with various cellular structures were obtained by controlling coagulation bath compositions and temperatures. The effects of chemical structures, cellular structures on dielectric property of cellular polyimide films were studied. The results showed that all of the cellular polyimide films had lower dielectric constants than the polymer matrix. The dielectric properties were influenced dominantly by the morphologies of the films. Cellular Polyimide films filled with uniform small cellular structures behaved excellent dielectric property compared with those large-pore cellular films. These findings would provide potential application for cellular polyimide films in microelectronic devices.

Preparation and characterization of BiFeO 3/LaNiO 3 heterostructure films grown on silicon substrate

BiFeO 3/LaNiO 3 (BFO/LNO) heterostructure films are fabricated directly on Si (1 0 0) substrate. The LaNiO 3 layer, which is prepared by chemical solution deposition, is used both as the seed layer to improve the quality of BiFeO 3 layer, and as the bottom electrode for the electrical measurement. The BiFeO 3 layer, which is fabricated by pulsed laser deposition, presents compact microstructure with grain size about 100 nm. Saturated hysteresis loops of polarization vs. applied voltage have been measured at the frequency of 1 kHz. The value of remnant polarization is about 40 μC/cm 2. The frequency dependence of capacitance and loss tangent of the heterostructure is also studied. All the results of the electrical measurements indicate that the effect of leakage current has been suppressed in the BFO/LNO heterostructure. The results are significative for the application of BiFeO 3 films in microelectronic devices.

Dielectric properties of sol–gel derived CaCu 3Ti 4O 12 thin films onto Pt/TiO 2/Si(1 0 0) substrates

The ultrahigh relative dielectric constant ( K′) values reported for the CaCu 3Ti 4O 12 bulk ceramics (10 4 at RT) joined to their low thermal dependence, no phase transitions are expected between −173 and 330 °C, make this material very promising for capacitor applications and certainly for microelectronics. The interest in the preparation of this material in thin film form is twofold, the understanding of its physical properties and the integration of this high K′ oxide with the Si technology. In this work, the preparation of CCTO thin films onto Pt/TiO 2/SiO 2/Si(1 0 0) substrates is attempted using sol–gel processing and rapid thermal processing (RTP) at 650 °C. Structural, microstructural and dielectric characterization of the films is performed. The results are commented and discussed on the light of the grain boundary effect on the dielectric constant and the possibility of application of these thin films in microelectronic devices.

Coverage properties of silicon nitride film prepared by the Cat-CVD method

The coverage properties of silicon nitride (Si 3N 4) films prepared by the catalytic chemical vapor deposition (Cat-CVD) technique were systematically studied. By increasing the catalyzer–substrate distance, the coverage was improved from 46 to 67% on a 1.0-μm line and space pattern. The etching rate of Cat-CVD Si 3N 4 film measured using 16BHF solution was independent of the deposited position of the micro-patterns deposited, and was approximately 3 nm/min, one order of magnitude lower than that of plasma-enhanced CVD (PE-CVD) Si 3N 4 film. This means that Cat-CVD Si 3N 4 films are denser than PE-CVD Si 3N 4 films, and that the quality at the side wall is equivalent to that on the top surface. That is, Cat-CVD Si 3N 4 films show a passivation effect, which was excellent, even at the side wall of micro-patterns. These results suggest that Si 3N 4 films prepared by Cat-CVD are suitable for the passivation films in microelectronic devices having a step configuration, such as TFT-LCDs and ULSIs.

Expanding Thermal Plasma Deposition of Silicon Dioxide-Like Films for Microelectronic Devices

AbstractIn this paper we report on the use of the expanding thermal plasma (ETP) technique for the deposition of carbon-free SiO2 films by means of hexamethyldisiloxane (HMDSO)/oxygen mixtures, at a growth rate of 8-10 nm/s. Information concerning the film chemical properties and refractive index/growth rate have been obtained by means of FTIR measurements and in situ single wavelength ellipsometry, respectively. Because of its geometry, the ETP configuration has proven its suitability for studies concerning the fragmentation paths of the HMDSO molecule and the reactions occurring in the plasma phase. In this framework, very recent results obtained by coupling the SiO2 film-deposition set up with a very sensitive, high spectral resolution- absorption technique, Cavity Ring Down Spectroscopy, are presented.

Swelling behavior of thin anisotropic polymer layers

The swelling of thin anisotropic aromatic polymer films in microelectronic devices and micromechanical systems can lead to significant reliability problems. Polymer swelling is caused by the reversible sorption of gas molecules such as water or volatile organic compounds in the polymer. In this paper, we investigate the relationship between the number of sorbed molecules and the resulting anisotropic volume expansion, with particular focus on in-plane-stress and out-of-plane expansion. Based on analytical and phenomenological studies of the polymer-gas interactions we have developed a model describing the microphysical mechanisms of sorption and swelling. The model is valid for a variety of gases and polymers, the chemical and structural properties of which are available in the literature or may be measured directly.

Growth and characterization of HTSC thin films for microelectronic devices

General techniques for the growth of heteroepitaxial HTSC thin films are shortly reviewed, and some recent trends are emphasized. The crystallographic characterization of such films is described in detail, including various X-ray diffraction settings, as well as electron diffraction and channelling methods. Among physical characterizations, the microwave measurements are highly defect sensitive, and a clear correlation between the microstructure, the a.c. susceptibility losses and the surface resistance is reported. Finally, main trends about potential applications are given.

Application of conducting polymer technology in microsystems

Conducting polymers are a new type of organic material that offer enormous potential for application within the field of microsystems. In this paper we review the basic properties of conducting polymers and discuss their application in electronic, mechanical and (bio)chemical microsystems. For instance, we have found that thin films of poly(pyrrole)/decanesulfonate have both a low friction coefficient (ca. 0.1) and wear rate (ca. 1 nm cm−1) that are similar to values observed for PTFE, yet possess relatively high electrical and thermal conductivities. In addition, conducting polymers can be readily electrodeposited onto planar or curved micromechanical structures, such as microslideways, micromotors or microturbines, to provide a bearing material of superior performance to standard micro-engineered materials (e.g. Si, SiO2, Si3N4) and better processability than PTFE. In addition, conducting polymers can be used as gas-sensitive films in microelectronic devices. They have been shown to have a rapid, reversible ppm sensitivity to polar organic compounds (e.g. alcohols, ketones, aldehydes and fatty acids) without interference from common gases such as CO2, CO, CH4 and N2. Conducting polymers are currently being used in commercial electronic noses, and integrated microsystems are being realised with the advent of custom microsensor array devices and application-specific integrated circuit chips.

Microstructural study of YBa2Cu3O7/SrTiO3/YBa2Cu3O7 heteroepitaxial trilayer films grown on (100) SrTiO3 substrates

Detailed transmission electron microscopic study has been carried out on heteroepitaxial YBa2Cu3O7/SrTiO3/YBa2Cu3O7 trilayer thin films grown on (100)SrTiO3 substrates prepared by DC and RF magnetron sputtering. The microstructural results showed the existence of somea-axis-oriented YBCO grains 20–90 nm wide in thec-axis-oriented YBCO matrix. Some of thea-axis grains in the lower YBCO thin film layer have protruded into the above SrTiO3 layer, which may cause short circuit between the two YBCO superconducting layers. This is unsuitable for the application of trilayer thin films for microelectronic devices. The defects on the surface of the substrates would also influence the growth quality of the YBCO thin films.

Controlled Mass Flow of Low Volatility Liquid Source Materials

ABSTRACTChemical Vapor Deposition (CVD) of thin films for microelectronic devices has historically used source materials that are gases at room temperature [1]. The decision to use gases was largely a practical one based on the relative ease with which the flow of gaseous materials can be controlled. CVD of thin films plays a vital role in increased circuit density and performance of integrated circuits. Liquid sources offer alternative source composition, reaction kinetics and reaction mechanisms to optimize a given CVD process [2].For example, CVD films of silicon dioxide (oxide) and oxide films modified to lower the glass transition temperature such a borophosphosilicate glass (BPSG) have traditionally used gaseous source materials such as silane, diborane and phosphine [3]. An all liquid system of tetraethylorthosilicate (TEOS), triethylborate (TEB) and triethylphosphine (TEPhine) has been found to offer superior conformality and overall safety [4]. However, from a practical standpoint, the all liquid system has historically suffered from reliable, reproducible mass flow control.