Screen printing: a technology for partitioning integrated microsensor processing

Potentiometric chemical sensors are presented as a case study in the use of screen printing for process partitioning. After CMOS processing, the authors print silver epoxy over the openings in the overglass layer to the aluminum input pads; the silver forms a stable chemical interface to the membranes, and the epoxy forms a strong physical bond to them. The screen-printed silver epoxy allows the use of conventional aluminum metallization in the microelectronic circuits. The polymeric membranes are applied and patterned with screen printing. Membranes of different compositions can be deposited on the various sites of a multisensor chip by simply repositioning the mask and repeating the screen print/cure cycle. There is no cross-contamination of membranes.<>