Section B.1. Die


B.1. Die

A die consists of an individual tag microchip on a silicon wafer. A silicon wafer is a circular slice of silicon a few inches in diameter (generally 8 inches) on which a significant number of microchips can be produced.

This manufacturing step generally consists of the following substeps:

1.

Produce microchips on the silicon wafer.

Chemical etching processes (also known as photolithographic processes) are used to produce several hundred to thousands of tag microchips on the silicon wafer.

2.

Test.

The individual microchips on the wafer are tested for functionality. Metal points are generally used in this testing to access the chip directly via its specialized contact fields. The chip is placed in a test mode, in which all its functionalities can be tested comprehensively. All defective chips are marked with a color code so that these can be identified and removed later. After the testing has been completed, the test mode of the microchip is permanently deactivated by blowing specific fuses on the chip (which prevents any unauthorized data access at a subsequent stage).

3.

Embed unique serial numbers.

This step is generally performed with the previous (testing) phase where a unique serial number is programmed into the chip's memory (for example, EEPROM). For a read-only (RO) tag, this is done at the hardware level by blowing a set of fuses of the microchip with a fine-pointed laser beam.

4.

Separate individual microchips (dies).

Typically, a diamond saw is used to cut the wafer up and separate the individual microchips on the wafer. However, these saws also destroy a part of the silicon that might have been used for producing more microchips. Therefore, alternative methods may also be used, especially when the microchips are very small (for example, 300 microns or less).

5.

Embed a die into a substrate module.

This is an optional step. Individual dies are embedded into a module on some kind of a substrate (for example, plastic). If the tags are too tiny, this step might not be feasible in terms of cost and capabilities of existing equipment. In this case, alternative methods need to be developed.



    RFID Sourcebook
    RFID Sourcebook (paperback)
    ISBN: 0132762021
    EAN: 2147483647
    Year: 2006
    Pages: 100
    Authors: Sandip Lahiri

    flylib.com © 2008-2017.
    If you may any questions please contact us: flylib@qtcs.net