Novel Manufacturing Technologies for GHZ/THz Integrated Circuits on Synthetic Diamond Substrates.

摘要

A frequency multiplier with IMPATT diode having high multiplication ratio served as a device demonstrating the advantages of diamond application as substrate. We chose output frequencies of 280 GHz and 360 GHz to perform analysis and calculations. Choosing of diamond substrate thickness is a complex problem. One should decrease the dielectric thickness as frequency grows to reduce the transmission line width. On the other hand, in that case the transmission line losses increase. Thus, the above problem is to be considered separately for each specific application. We chose diamond thickness of 30 microns for multiplier realization. The successful development and simulation of the elements of frequency multiplier with high multiplication ratio that have satisfactory parameters indicate possibility of realization of ICs on diamond substrates. In the course of our studies it was found that the Ti-Pd-Au metallization system (thickness of 2-3 um) can be applied when forming the topology of IC elements on synthetic diamond layers, while the Cr Cu Ni Au metallization system with thick (up to 50 um) copper layer can serve as screen heat sink and HIC elements carrier. The technical documentation on fabrication of photomasks for IC topology formation in frequency multipliers with silicon IMPATT diodes with operating frequencies of 280 GHz and 360 GHz was developed. A manufacturing scheme for diode based on the silicon thin membrane technology was developed. The photomasks were designed and fabricated to realize the manufacturing scheme. A set of photomasks ensures formation of beam leads and mesas using the double-sided photolithography. The technological processes were refined in accordance with the manufacturing scheme. The silicon beam-lead IMPATT diode parameters (differential resistance and capacitance) can be adjusted to the required values after diode mounting in IC.