DFT Digest

In my DAC and DFT - post #2, I linked to an article at Test & Measurement World, that briefly outlined a few different ‘new’ DFT technologies being pursued by the big EDA companies. One of these areas was termed volume diagnostics or defect diagnostics. This ‘new technology’, to me at least, is more DFM than DFT, but I’ve said from the beginnings of this blog that DFT has an important part to play in this new acronym.

The concept behind this is that data collected during test, especially scan test (ATPG), can be used to track down problems - in the layout. As I poke around the online information, I get the feeling that defect diagnostics refers to the ability to import test (ATPG) data into a physical design environment and locate the probable site of a defect. Volume diagnostics, I think, refers to the same thing on a larger scale - in other words going from failure analysis to yield analysis, or going from analyzing a possibly random defect to a systematic defect, that may be present due to the way the IC was designed and laid out.

This data collection is the subject of an open meeting of the STDF Fail Data Standardization group at Semicon West next week.

Anybody out there have a better understanding? Please, speak up, and share…

Operating completely on press releases, product datasheets and a lack of sleep, I came up with some offerings from the big 4 relating to diagnostics:

Mentor’s diagnostics tool is called YieldAssist, and claims to be able to take FastScan ATPG data (compressed or otherwise), process it, and find likely failure locations in the physical layout database (using Calibre, Mentor’s flagship physical layout environment). For yield learning (volume diagnostics), Calibre YieldAnalyzer is used.

For failure location, Synopsys has linked it’s TetraMAX ATPG failure data with the Milkyway database. For volume diagnostics, it has linked it with the Odyssey Yield Management System.

Cadence has Encounter Diagnostics, with a “universal ATPG support”, which I suppose means that it can take any ATPG results and process it - and that brings up a good point - when any tool reads ATPG data, it’s really the ATEs format that it’s reading, right? The only time that a little secret sauce is needed, is when there is test compression involved. Otherwise, a simple knowledge of the scan chain architecture is all that’s needed.

Magma has YieldManager. It manages data from many different sources, and sounds more like a statistical package than an EDA tool (I remember using RS/1 to do analysis, way back in the day). But that’s admittedly just my opinion from a quick look at the datasheet.