On the trail of counterfeit chips

Many counterfeit electronic devices, like a cell phone or MP3 player, contain fake or modified chips. Counterfeits take many forms. Some are simply stolen devices or dice that have been repackaged. Others may have failed manufacturer testing. Instead of being destroyed, they are sold as functional devices. One-time-programmable (OTP) parts such as EPROM or microcontrollers may be sold unprogrammed. Counterfeit versions of high-value parts like FPGAs or microprocessors may turn out to be unrelated, cheaper parts that have had the original package markings removed and replaced with markings from a high-value device. Devices with readable device codes, such as NAND flash, can be modified to return the device code of a higher-density device. For example, a 256-Mbit part can be modified to respond with the device code of a 1-Gbit device. Copied devices also exist and it is possible to have new, compatible designs that have been branded with a high-brand-value name.

Manufacturers can easily identify counterfeit chips in various ways, depending on the type of device. Some can be verified with test equipment and fixtures to test the devices' functionality. Memory testers will reveal flash chips returning incorrect device codes. Trying to program an OTP device that has already been programmed will usually result in a programming error. Data codes and batch numbers can likely ID devices that failed the manufacturer's test.

The challenge comes in what to do when counterfeit versions of products are identified. Knowing where the devices were purchased is a starting point, but distributors of counterfeit devices will typically be unaware that the devices were not genuine. Even if the distributor knowingly sold the counterfeit parts, putting him out of business will not stem the tide from the source. Ideally, you want to find out who is responsible for the device. This involves identifying the designer or copier of the device.

Assuming a counterfeit device with performance similar to or exactly like the genuine article, it can be de-encapsulated to determine whether the die is from the manufacturer, a copy of the manufacturer's part or a completely new design. Most legitimate chips are identified by a die marking or part number, or both, while a copied design is unlikely to have any such markings. Small differences in layout can also reveal a copied design. The next step: determining the foundry that made the device.

Foundry identification walks the line between art and science, involving a close comparison of specific features on the faked chip to other, known samples of the foundry's work to determine if they are the same. Each foundry has unique processes and methods of manufacture that leave "signatures" in the finished product.

The world's two major fabless semiconductor foundries, according to Gartner Dataquest, are Taiwan Semiconductor Manufacturing Co. Ltd, with a 44.8 percent market share last year, and United Microelectronics Corp., with 15.4 percent. Semiconductor Manufacturing International Corp. of China came in at about 7.5 percent.