Comparative Study on Metallization and Passivation Materials for High Temperature Sensor Applications

Abstract

We investigated the performance of different metallization/passivation systems for high temperature applications. The metallizations comprised a 150 nm sputtered Pt or a 150 nm e-beam evaporated PtRh layer on Ti/TiN underlayers, respectively. The passivation coatings consisted of amorphous PECVD SiOx, of amorphous stress-reduced PECVD SiNy, and of a SiOx/ SiNy stack. For samples with SiOx and SiOx/ SiNy passivation layers the electrical properties changed after a short high temperature anneal at 600 °C but then remained stable during further annealing. This was attributed to the formation of PtTi alloys, which stabilized the metallization stack. In samples with SiNy passivation a significant Pt out-diffusion into the passivation layer was observed. This led to a degradation of the electrical and mechanical properties. The best performance was achieved with Pt-based metallizations and SiOx or SiOx/SiNy passivations.

Structural and Reliability Analysis of Ohmic Contacts to SiC with a Stable Protective Coating for Harsh Environment Applications

“…This is in good agreement with results obtained in an analogous study on the Ti/TiN/Pt/Ti interconnects. 11 The intermixing processes taking place in the interconnect stack are seemingly not influenced by the presence of the alloyed Ti layer below. In the contact region, no increase of the total oxygen content occurred during the aging.…”

“…The top 20 nm Ti adhesion-promoting layer was necessary to ensure a good adhesion of the protective coating. 11 The protective coating was deposited by PECVD and consisted of an a-SiO x /a-SiC stack (nominal thickness 250/250 nm). More details on the protective coating and the Pt interconnects can be found in Refs.…”

“…In these environments the oxidation dynamics is largely enhanced because of the presence of moisture up to 10% concentration. 9,10 We have recently developed stable protective coatings based on PECVD amorphous silicon oxide (a-SiO x ) and amorphous hydrogenated silicon carbide (a-SiC) and studied their suitability for harsh environment applications up to 700 • C. 11,12 In following work, the developed protective coatings were successfully implemented to enhance the stability of Ni and Ti ohmic contacts to n-SiC 13 and achieve thus excellent SiC-MISFET stability benchmarks. 14 In this work we present a comprehensive structural and reliability analysis on Ni and Ti-based contact metallizations with an a-SiO x /a-SiC protective coating.…”