Thin-Film RF/Microwave Capacitor Technology Accu-P 555 Accu-P Thin-Film Technology This accuracy sets apart these Thin-Film capacitors from THE IDEAL CAPACITOR ceramic capacitors so that the term Accu has been The non-ideal characteristics of a real capacitor can be employed as the designation for this series of devices, an ignored at low frequencies. Physical size imparts inductance abbreviation for accurate. to the capacitor and dielectric and metal electrodes result in resistive losses, but these often are of negligible effect on the circuit. At the very high frequencies of radio communication THIN-FILM TECHNOLOGY 1 (>100MHz) and satellite systems (>1GHz), these effects Thin-film technology is commonly used in producing semi- become important. Recognizing that a real capacitor will conductor devices. In the last two decades, this technology exhibit inductive and resistive impedances in addition to has developed tremendously, both in performance and in capacitance, the ideal capacitor for these high frequencies is process control. Todays techniques enable line definitions of an ultra low loss component which can be fully characterized below 1m, and the controlling of thickness of layers at 100 in all parameters with total repeatability from unit to unit. -2 (10 m). Applying this technology to the manufacture of Until recently, most high frequency/microwave capacitors capacitors has enabled the development of components were based on fired-ceramic (porcelain) technology. Layers where both electrical and physical properties can be tightly of ceramic dielectric material and metal alloy electrode paste controlled. are interleaved and then sintered in a high temperature oven. The thin-film production facilities at AVX consist of: This technology exhibits component variability in dielectric Class 1000 clean rooms, with working areas under quality (losses, dielectric constant and insulation resistance), laminar-flow hoods of class 100, (below 100 particles variability in electrode conductivity and variability in physical per cubic foot larger than 0.5m). size (affecting inductance). An alternate thin-film technology has been developed which virtually eliminates these vari- High vacuum metal deposition systems for high-purity ances. It is this technology which has been fully incorporated electrode construction. into Accu-P and Accu-P to provide high frequency capaci- Photolithography equipment for line definition down to tors exhibiting truly ideal characteristics. 2.0m accuracy. The main features of Accu-P may be summarized as follows: Plasma-enhanced CVD for various dielectric deposi- tions (CVD=Chemical Vapor Deposition). High purity of electrodes for very low and repeatable ESR. High accuracy, microprocessor-controlled dicing saws for chip separation. Highly pure, low-K dielectric for high breakdown field, high insulation resistance and low losses to frequencies High speed, high accuracy sorting to ensure strict above 40GHz. tolerance adherence. Very tight dimensional control for uniform inductance, unit to unit. Very tight capacitance tolerances for high frequency signal applications. Orientation Marking Alumina (Al O ) 2 3 Electrode Seal (SiNO) Dielectric (SiO / SiNO) 2 Electrode Alumina (Al O ) 2 3 Terminations ACCU-P CAPACITOR STRUCTURE 6