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Ph. Philippov, R. Arnaudov, N. Yordanov, V. Ianev and M. Gospodinova
Investigations of material parameters within the system Al, Al2O3, Ta, Ta2O5 and TaOxN1‐x are presented. This combination is characteristic when using Al sheet for…
Investigations of material parameters within the system Al, Al2O3, Ta, Ta2O5 and TaOxN1‐x are presented. This combination is characteristic when using Al sheet for production of substrates including electronic interconnections, vias and resistive groups. They can serve for MCMs due to the specific features of Al. The technological process includes first electrochemical oxidation of Al‐sheet as base isolation layer Al2O3 (50‐70μm). This process is followed by vacuum deposition of relatively thick layers of Al (2‐5μm). Each layer is then processed by lithographic methods followed by selective electro‐chemical oxidation as a help process for structuring. The development of this combined structuring method allows the simultaneous achievement of interconnections (Al) and isolation (Al2O3) levels with least size up to 50μm. The importance of the method consists of a vertical combination of several conductive layers of Al structured as described above, “burying” the interconnections in the insulating Al2O3 films. All necessary combinations and configurations of different kinds of microstrip lines are possible. The dielectric characteristics of Al2O3, achieved through the above mentioned method, can be changed in accordance with the parameters of the technological steps and filling of the porous structure. Thus some interesting high frequency features of microstrips are obtained. Extra advantage is the ability of combination of conductive Al layers with other types of such layers as tantalum (Ta). With Ta can be achieved other permittivity constants of the insulation layers and in combination with TaOxN1‐x intermediate planes of resistive groups are developed. The measurement of the stripline parameters is done by microwave technics, because the desired application of the substrates is for high‐speed digital signals in the GHz range.
Ph. Philippov, R. Arnaudov, N. Yordanov and M. Gospodinova
In this paper we present recent studies on the electrochemical migration processes in Ag thin film parallel microstrip lines in MCM(D) structures. The basic concept is…
In this paper we present recent studies on the electrochemical migration processes in Ag thin film parallel microstrip lines in MCM(D) structures. The basic concept is applying accelerated local drop‐test of water solutions onto the surface of two adjacent lines, under a given voltage potential. These operational conditions are often met in the interconnection line buses, placed in the top assembly level of multilayered hybrid structures. The subject of investigations are MCM(D) developed on Al‐sheet carrier with internal conducting and isolating layers, produced through unique selective electrochemical anodization of Al and Ta. This technology process also enables the creation of embedded R and C passive components on the base of TaOxN1‐x and Ta2O5 (or Al2O3) respectively. We propose an electrochemical deposition of Ag/Sb alloys on the surface of Al interconnection lines and contact pads to ease the bondability and solderability in chip mounting procedures. The artificially created silver migrated defects and partial shorts are investigated through the high frequency method of coupled transmission lines in order to eliminate the errors and insufficient validity of DC direct measurements.