Sensitive Electrical Monitor for Determining Open Collector Contacts
Original Publication Date: 1988-Mar-01
Included in the Prior Art Database: 2005-Feb-15
A method has been proposed to detect metallurgical opens on steep steps in semiconductor devices. It suggests building a latch-type circuit on the test sites to detect open collector contact problems. In semiconductor bipolar technology there is a concern over the adequacy of the Al-Cu-Si metallurgy's covering the steep step heights inherent in the designs. A sensitive electrical monitor, the SL2 latch, as shown in the drawing, has the topology required to create a step between the collector contact and the recessed oxide isolation (ROI) surrounding it. Metal going over the ROI step and reaching the contact makes the electrical connection. If there is a metal discontinuity going over the step, the emitter follower (EF) will be ON and the output of the EF will be stuck at an UPLEVEL. This is irrespective of inputs C.O.