ForumWhat are the causes and prevention techniques of latch-up in VLSI?
AvatarSemiconwiki Staff asked 2 weeks ago
I think the main cause of latchup in Bulk CMOS is the parasitic bipolar transistors formed within the structure. When both BJTs conduct, they create a low resistance path between Vdd and GND, leading to latchup. Preventing latchup is necessary, and using guard rings and well tap cells can help reduce the resistance and prevent the feedback loop from forming.
2 Answers
AvatarVLSI Master answered 1 week ago

In my opinion, latchup prevention should focus on reducing the gain of the parasitic BJTs. Techniques like using a buried n+ layer or adding a guard ring around wells are usefull. These methods help in decreasing the gains of the parasitic transistors and stop the feedback loop that leads to latchup.

AvatarCircuitDesigner answered 1 week ago

Preventing latchup involves both design and system approaches. On the design side, reducing well and substrate resistances and using guard rings can help. On the system side, avoiding sudden transients on power or ground buses and protecting against ESD can prevent the conditions that lead to latchup. Techniques like SOI and STI technology can also eliminate latchup issues completely.