Substrate mapping

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Substrate mapping is a process within semiconductors which supports data maps for wafers, frames, trays and strips in the semiconductor device fabrication process. It supports for example the wafer testing and die attachment process without using ink.

[edit] History

A wafer map: different bins are represented by different colours

A strip map: this strip map represents five panels on one strip. The lowerleft square around the die on each panel represents a reference die, which is used to align between wafer testing and die attachment

The initial process supported by substrate maps was inkless binning. This name is a fusing of 'ink' and 'bin'. In the very early days of wafer test, the dies were put in different bins or buckets, depending of the test results. Currently a die still gets a bin value, depending of the result of the test. A good example is that a bin get a value of 1 for a good bin, or pass die, and bin 10 for a circuit shortage, and for example bin 11 for an open circuit. So in the end it is known why the die failed. The next step in the process was not putting dies in a bin, but mark the failing dies with ink, and during assembly only dies without ink were picked up from the wafer, and used for final assembly. Nowadays we don't use physical bins anymore, and ink is no longer in use either. A better way to describe this process would be electronic wafer mapping, as electronic files are used with information of the wafer. As this process is in the present time not exclusively being used for wafers, the name substrate mapping is used, to address that it can be used for other areas in the semiconductors process as well: frames, trays and strips.

[edit] E142

As with many items in the Semiconductor process area, also for this process step there are standards available. The latest and most potential standard is the E142 standard, provided by the SEMI organization. This standard has been approved via ballots for release in 2005.

It supports many possible substrate maps, including the ones named above. While the old standards could only support standard bin maps, representing bin information, this standard also support transfermaps, which can help in tracing back dies on strips to the locations they come from of the wafer for example.

[edit] External Links

• SEMI organization: organization which is working on semiconductor process standards.