New crossover operators for GA-based synchronous sequential circuit testing
M. C. Bhuvaneswari, S. N. Sivanandam · Indian Journal of Engineering and Materials Sciences · 2003
Rapid advances in testin g of integrated circuit techn ology ha ve made it possibl e to fabricate di g it al circuit s with large number of devices o n a singl e chip. The advant ages of integ rated circuits are reduced sys tem cost, bett er perform ance and reliability. These advantages would be los t unless integrated circuit devices can be economically tested. Testin g is one of th e important field s, whi ch validate th e functi onality of any manufacturing process. Manufacturing testin g is esse nti al to reduce th e ri sk of shipping a defectiv e product and is a process where circuit inputs are exercised usin g certain patt ern s and th e resulting response is compared to th e gold en res ponse to elimin ate th e defective parts. Due to th e complexity of th e IC manufacturing process, a number of defects mi ght occur during fabric ation and hence no process can guarant ee 100% yield. Therefore, testi ng is a very important aspect of any VLSI manufacturing sys tem l~ . The o bj ecti ve of automatic test patt ern ge nerati on is to obtain a set of test vectors that will detec t any defect th at mi ght occur 111 th e manufacturing process. The e ffe cts of manufacturin g defects are rep resent ed at the logic level usin g a fault model. Fa ult models can describ e th e faults at different abs trac ti on levels. The widely used gate level fault model for di g it al c ircuit s is th e si ngle stu ck-at fault model. Thi s model ass umes th at any physical defect in a digital circu it results in a node in the circuit being fixed eith er at logic 0 or lo g ic I and appropriately ca ll ed stu ck-at -O and stu ck-at-l , respecti ve ly . These faults occur most frequently in Complement ary Metal Oxid e Semiconductor (CMOS) process tec hn o logy due to thin ox id e sho rt s (the n transistor ga te to VSS or th e p tr ansistor gate to VDD) or metal-t o-metal shorts I.