Al-sheet as substrate for one- or multilevel package consisting interconnections, VCAs and R-matrix

摘要

Investigations of material parameters within the system AL, AL_2O_3, Ta, Ta_2O_5 and TaO_xN_(1-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 AL_2O_3 (50-70 μm). This process is followed by vacuum deposition of relatively thick layers of Al (2-5 μm). 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 (AL_2O_3) levels with least size up to 50 μm. The importance of the method consists of a vertical combination of several conducting layers of Al structured as described above, "burying" the interconnections in the insulating AL_2O_3 films. All necessary combinations and configurations different kinds of microstrip lines are possible. The dielectric characteristics of AL_2O_3, 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 constant of the insulation layers and in combination with TaO_xN_(1-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.