IBM Makes a Multi-bit Phase Change memory chip

                                                     Scientists from IBM research have demonsrated of  "Reliable Multi-bit Phase-Change Memory [PCM] technology." PCM involves the use of materials that will change between crystalline and amorphous states, the electrical resistance of the two states having different levels-data is stored in binary form, using one level to represent 0, and the other to represent a 1. By applying this new methods/techniques of existing PCM technology data can be written 100 times faster within a flash.

The IBM team used a 200,000-cell  PCM test chip, fabricated in 90 nanometer CMOS technology. The phase changing material consists of an alloy of various elements which will deposit between the two electrodes in the chip. Next the alloy will be heated by applying voltage to those electrodes which will cause it to change back and forth between its low-resistance crystalline state, and its high resistance amorphous state.

After some days the researchers met with a problem  was  resistance drift or the tendency of the amorphous material's resistance which might have gradually increased  after initial phase change.this resulted in giving errors. To solve the problem the Swiss researchers utilized an 'advanced modulation coding technique ,"
As a result of this the chip has been able to  reliably retain data upto 5 months, and counting.

Another benefit was that it created  read and write processes which allowed for deviations of resistance, caused by variations within the cells and the alloy itself. Even it works slowest but however the chip had a writing speed of about 10 microseconds -reportedly it is 100 times faster than the most advanced Flash memory systems currently available.

PCM chips are generally  said to be more durable than traditional technology. The IBM research team believe this technology could be ready for use by 2016.

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