Studies on buried layer resistors

Abstract

Multilayer thick-film technology is one of the important technologies adopted in the miniaturization of electronic systems. Generally, only interconnections are made in the intermediate layers. The possibility of fabricating resistors along with interconnections in the buried layers/intermediate layers using conventional thick-film materials has been examined in this study. The fabrication has been carried out by processing layer after layer. It has been found that the buried layer resistors exhibited a sheet resistivity lower than those fabricated as open resistors. This change in sheet resistivity has been attributed to multiple firings that the resistors undergo during the fabrication. This reduction in sheet resistivity has been found to be due to segregation of active materials. A model has been proposed to explain this change in sheet resistivity through segregation of the active material. The work reported in the paper clearly indicates that buried resistors with consistent values (±10%) can be fabricated using conventional materials. However, the design of the resistors has to be carried out using modified sheet resistivities. The model that is proposed also indicates how one can make a paste that is likely to exhibit the same sheet resistivity for buried resistors and open resistors.