METEOR: a constraint-based FIR filter design program

It is proposed to specify a filter only in terms of upper and lower limits on the response, find the shortest filter length which allows these constraints to be met, and then find a filter of that order which is farthest from the upper and lower constraint boundaries in a minimax sense. The simplex algorithm for linear programming is used to find a best linear-phase FIR filter of minimum length, as well as to find the minimum feasible length itself. The simplex algorithm, while much slower than exchange algorithms, also allows the incorporation of more general kinds of constraints, such as concavity constraints (which can be used to achieve very flat magnitude characteristics). Examples are given to illustrate how the proposed and common approaches differ, and how the proposed approach can be used to design filters with flat passbands, filters which meet point constraints, minimum phase filters, and bandpass filters with controlled transition band behavior     

A novel technique for fabrication of metallic structures on polyimide by selective electroless copper plating using ion implantation

The successful use of palladium ion implantation into polyimide to seed an electroless plated film of copper on the polyimide surface is reported. Polyimide (Hitachi PIX 3400) was implanted with palladium ions to doses of 1.5 × 10¹⁵ − 1.2 × 10¹⁷ ions cm⁻² using a MEVVA ion implanter. The implanted ions acted as sites for nucleation of copper film. A copper film was then deposited on implanted polyimide using a commercial electroless plating solution. The ion energy was kept low enough to facilitate a low critical ‘seed’ threshold dose that was measured to be 3.6× 10¹⁶ Pd ions cm⁻². Test patterns were made using polyimide to study the adaptability of this technique to form thick structures. Plated films were studied with optical microscopy, Rutherford Backscattering Spectrometry (RBS) and Profilometry. The adhesion of films was qualitatively assessed by a ‘scotch tape test’. The film growth (thickness) was observed to be linear with plating time. A higher implantation dose led to greater plating rates. The adhesion was found to improve with increasing dose.     

Comparative study of crystallization processes in Sb2Te3 films using laser and thermal annealing techniques

Adherent and pin-hole free amorphous Sb₂Te₃ thin films have been obtained by vacuum evaporation at substrate temperatures ≤25 °C. The films have been crystallized by thermal and laser annealing, and the crystallization processes monitored as a function of annealing temperature and laser scan speed. A comparative study of topography reveals disk-shaped crystallized areas in thermal crystallization and dendrite growth in the laser induced process. The crystallized films in both cases contain a single Sb₂Te₃ phase. Activation energy of 2 eV for crystallization, determined using differential scanning calorimetery indicates good room temperature stability of the amorphous states.