Feasibility Study of Two-Step LIGA-Fabricated Circuits Applicable to Millimeter/Submillimeter Wave Sources

• Main Authors: Park, G S, Shin, Y M, So, J K, Han, S T, Jang, K H, Kim, J H, Chang, S S
• Format: Conference Proceeding
• Language: English
• ISSN: 0094-243X
• DOI: 10.1063/1.2158792

Some baffling technical problems such as miniaturization and threshold reduction have impeded micro-vacuum electronic devices from proper application in the millimeter/millimeter wave region. Two-step LIGA, proposed to construct three-dimensional circuit elements within minimum tolerances on the micron scale, is applied to a traditional vacuum electron device - the folded waveguide backward wave oscillator (FWBWO) - and to novel counter-streaming electron beam oscillators (CSEBOs) for the first time. Circuit characteristics of these devices, in particular those related to excellent higher frequency adoptability, are discussed with design optimization and numerical analyses provided by MAGIC3D simulations. FWBWO and CSEBO circuits were fabricated by the two-step LIGA process and cold-tested. The discrepancy between measured and simulated dispersion and phase-velocity characteristics is about 1.4%. Also, the surface roughness of the LIGA-fabricated circuit was measured to be 70 nm by AFM. Cold testing of the FWBWO and the CSEBO circuits suggests that the two-step LIGA process appears to be a very suitable method in the higher frequency application beyond the frequency range of 100 GHz. More precise alignment for the two-step process and improved electroplating processes should demonstrate promise for this method for future terahertz (THz) applications.