- Application Details
The process took a day – interviewed at SNOCAP in February 2008.Interview Details
2) In an IC layout, what is a polygon and what is a path?
What are the advantages and disadvantages of each?
A polygon is a polygon and a pad is a pad. A pad can be easily edited and reshaped, however, it’s off grid with 45 degree angle. Polygon is always on-grid, unless it’s a copy and flip. However, polygon is hard to edit and work with.
13) What is the difference between a contact and a via?
What is a “stacked” via process?
Via: a contact between two conductive layers.
Contact:Opening in an insulating film to allow contact to an underlying electronic device.
The placement of vias directly over the contacts or other,lower vias is known as stacked via.
14) Why is it that NMOS transistors can be created directly in a P-type substrate, whereas PMOS transistors must be created in an N-type well?
15) Why must transistors be provided with “bulk” connections?
What voltage levels are connected to a p-type substrate and an n-type well through these connections, and why?
To make the parasitic diodes reverse biased.p type substrstrate is generally connected to the most negative supply and n well is connected to the most positive supInterview Questions
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