Deposition of Low-Resistivity Aluminum Thin Films Via Application of Substrate Bias During Magnetron Sputtering

In this study, the critical role of substrate bias during the sputter deposition of Al thin films is discussed. Two sets of Al thin films having a nominal thickness of 300 nm were deposited at sputtering pressures of 4.1 and 1.5 mTorr, respectively, with an applied negative substrate bias in the range of 0-200 V. It was found that the microstructure, surface roughness, film resistivity and grain size were greatly altered by the combination of bias magnitudes and sputtering pressures. The sputtering pressure of 4.1 mTorr resulted in greater changes in the film properties with the application of substrate bias, and a lesser but still significant degree was observed for the films deposited at 1.5 mTorr. The resistivity values for the films deposited at 1.5 mTorr were found to be significantly lower, with the lowest resistivity value of 3.1 µΩcm achieved at a substrate bias of 50 V. Based on grain size measured by the line intercept method and MayadasShatzkes grain boundary scattering model, the resistivity contribution of grain boundary scattering for the lowest-resistivity film was found to be 0.37 µΩcm, which indicates that the film resistivity in the optimized condition is close to the known bulk resistivity of 2.65 µΩcm.

Dependence of Resistivity on Thickness of Vacuum Deposited Copper Thin Films

In depth understanding of resistivity of metals is of utmost importance for optimizing circuit designs and electrical systems. In this study, we investigated the relation between film thickness (in the range of 25−350 nm) and film resistivity of Cu thin films, with respect to thin film temperature sensors. The films were deposited in a vacuum deposition chamber over pyrex substrates and the film resistances were measured using 4 point probe technique. The empirical relationship established by Lacy has been used along with our experimental results in order to calculate the constants relating the filmsubstrate compatibility, which influences the change of resistivity with thickness.

Low resistivity HfNx grown by plasma-assisted ALD with external rf substrate biasing

Application of an external rf substrate bias during the H2 plasma half cycle leads to a significant decrease in film resistivity resulting from a major reduction of O content and an increase in the Hf3+ oxidation state fraction in HfNx thin films

Silver Metallization on Porosified LTCC Deposited by Pulse Plating Technique

Present microelectronic devices especially when including high frequency applications are in need of highly integrated metallization technologies. Silver is considered as a future interconnection material for such devices and systems due to its low bulk resistivity of about 1.6 μΩ·cm at 20°C. Conventional thick film metallization techniques on low temperature co-fired ceramics such as screen printing are only partly capable of meeting the requirements in terms of lateral resolution and precision. Furthermore, on advanced surfaces such as porosified composite LTCC, also thin film metallization techniques (e.g. sputtering) meet their limits due to a poor coverage and hence, a low electrical conductivity. In this study, it is shown, that bipolar pulse plating of silver is capable of bridging the pores of the surface of the porosified substrate without penetrating them. The plated metallizations feature very fine grains with an average diameter of approx. 90 nm and a maximum up to 250 nm. The film resistivity being measured directly during annealing decreases at elevated temperatures above 90°C in air. Compared to the bulk value, the film resistivity of the ‘as deposited’ electroplated silver is increased, but can be improved down to 2 μΩ·cm with a TCR of 4.1·10−3 K−1 at 20°C by a subsequent annealing treatment at 500°C for 5 h in air. Since there is no measureable difference in resistivity between the galvanic silver deposited on non-porosified or porosified LTCC detected, the findings qualify the bipolar pulsed silver plating as an excellent choice for metalizing porosified LTCC substrates.

The effect of reactive ion etching parameters on the electrical properties and the removal of residual organics in spin-coated colloidal ITO films

ABSTRACTSpheroidal colloidal indium tin oxide (ITO) nanoparticles, about 6 nm in diameter, were synthesized in-house and films were fabricated from them on glass substrates by spin coating. These films had high electrical resistivity due to the presence of organic capping ligands around each nanoparticle. Although high temperature annealing has been shown to reduce film resistivity by over eight orders of magnitude, lower temperature processing is desirable for applications like flexible electronics. Colloidal ITO films were subjected to a series of alternating RIE treatments in oxygen (5 minutes duration per cycle) and in argon (1 minute duration per cycle); and parameters such as gas pressure, RIE power and number of cycles were varied. These RIE treatments were found to reduce the film resistivity significantly. Among the parameters studied, gas pressure during RIE was found to be the most important parameter that determined the effectiveness of the treatment. Residual carbon content variation characterization done by XPS depth profiles also indicated similar trends.

Influence of Direct Current Magnetron Sputtering Parameters on Electrical Properties of Copper Films

Cu thin films were prepared by DC magnetron sputtering on Si substrate, and the resistivities change by adjusting its sputtering parameters. It is found that the changes of the sputtering power and substrate temperature and working pressure can affect significantly the Cu film resistivity (ρ). The Cu films resistivity decreases with the increasing of sputtering power. As the substrate temperature “structure zone model” effect, the Cu film resistivity decreases when the substrate temperature was less than 150°C. The resistivities (ρ) begin to increase gradually at various temperatures ranging from 150°C to 300°C, but the rate of increase is not significant. The resistivity abnormal increases when the substrate temperature was 400°C. The Cu films resistivity increases with argon working gas pressure ranging from 0.15 Pa to 2 Pa.