Latch-up and radiation integrated circuit--LURIC: a test chip for CMOS latch-up investigation

A CMOS integrated circuit test chip (Latch-Up and Radiation Integrated Circuit--LURIC) designed for CMOS latch-up and radiation effects research is described. The purpose of LURIC is (a) to provide information on the physics of CMOS latch-up, (b) to study the layout dependence of CMOS latch-up, and (c) to provide special latch-up test structures for the development and verification of a latch-up model. Many devices and test patterns on LURIC are also well suited for radiation effects studies. LURIC contains 86 devices and related test structures. A 12-layer mask set allows both metal gate CMOS and silicon gate ELA (Extended Linear Array) CMOS to be fabricated. Six categories of test devices and related test structures are included. These are (a) the CD4007 metal gate CMOS IC with auxiliary test structures, (b) ELA CMOS cells, (c) field-aided lateral pnp transistors, (d) p-well and substrate spreading resistance test structures, (e) latch-up test structures (simplified symmetrical latch-up paths), and (f) support test patterns (e.g., MOS capacitors, p/sup +/n diodes, MOS test transistors, van der Pauw and Kelvin contact resistance test patterns, etc.). A standard probe pattern array has been used on all twenty-four subchips for testing convenience

Latch-up in CMOS integrated circuits

An analysis is presented of latch-up in CMOS integrated circuits. A latch-up prediction algorithm has been developed and used to evaluate methods to control latch-up. Experimental verification of the algorithm is demonstrated

Latch-up control in CMOS integrated circuits

The potential for latch-up, a pnpn self-sustaining low impedance state, is inherent in standard bulk CMOS structures. Under normal bias, the parasitic SCR is in its blocking state, but if subjected to a high-voltage spike or if exposed to an ionizing environment, triggering may occur. Prevention of latch-up has been achieved by lifetime control methods such as gold doping or neutron irradiation and by modifying the structure with buried layers. Smaller, next-generation CMOS designs will enhance parasitic action making the problem a concern for other than military or space applications alone. Latch-up control methods presently employed are surveyed. Their adaptability to VSLI designs is analyzed