In the changing VLSI test environment, this paper re-examines the VLSI Test development trade-off of quality, cost of Test development and Time-to-Market. The paper looks at what technology has been available in the recent past and is currently available to reduce Time-to-Market in terms of Design-for-Test, the types of Test, and automation possibilities. Finally it briefly looks at future opportunities for the contribution of VLSI Test to the reduction of Time-To-Market for a VLSI chip.
The quiescent Vdd-GND current(I_<DDQ>) of a defect-free CMOS circuit is usually very small while a defective circuit often draws excessive I_<DDQ>. As a result, I_<DDQ> information is useful in testing and failure analysis of CMOS circuits. Moreover, it has been shown that the stuck-at fault model and logic testing can not cover some sefects in a CMOS circuit. Thus, I_<DDQ> information is also indispensable in performing high-quality testing and highly efficient failure analysis. This paper uses the transistor short fault model and describes the principle of I_<DDQ> testing, methods of selecting I_<DDQ> test vectors and ways of conducting fault diagnosis with both I_<DDQ> and logic information.