It's been a long haul for phase change memory, but the goal is in sight.
Numonyx, the memory joint venture between STMicroelectronics and Intel, is already shipping samples of phase change memory (PCM) chips to customers and will start shipping PCM chips commercially later this year, CEO Brian Harrison said at a press conference Monday.
"We expect to bring it to market this year and generate some revenue," Harrison said. "It is one to two years before it becomes widely commercially available."
Hearing a CEO talk about existing samples and near-term commercial shipments is a big deal for PCM. The technology has been stuck in the proverbial "a few years away" phase for a long time.
"It could be cheaper than flash within a couple of years," analyst Richard Doherty in said in 2001, predicting the technology might hit the market in 2003.
"We are making good progress," Stefan Lai, one of Intel's flash memory scientists, said in 2002.
Gordon Moore, co-founder of Intel and the man for whom Moore's Law was named, had an article in the September 28, 1970 issue of Electronics predicting that Ovonics Unified Memory, another name for the same type of memory, could hit the market by the end of that decade. (The same issue of Electronics also included this article: "The Big Gamble in Home Video Recorders.")
The delays have largely stemmed from two sources. First, it's not an easy technology to master. In phase change memory chips, a microscopic bit on a substrate gets heated up to between 150 degrees and 600 degrees Celsius. The substrate is made of the same stuff as CD disks. The heat melts the bit, which when cooled solidifies into one of two crystalline structures, depending on how fast the cooling takes place. The two different crystalline structures exhibit different levels of resistance to electrical current, and those levels of resistance in turn are then as ones or zeros by a computer. Data is born.
Both Intel and ST made a significant amount of progress in controlling the material in the past few years, Harrison said.
Size matters
Second, the makers of flash memory have continued to improve their technology. Back in 2001, some believed that flash would hit a wall at the 65-nanometer level of chip design. Then that got moved to 45 nanometers. Today, manufacturers mass-produce flash at 65 nanometers and have samples at 45 nanometers. Numonyx has samples of traditional NOR flash at 32 nanometers. Why switch when the existing technology continues to work?
Again, in the past few years, Intel and ST have made progress and figured out a way to produce PCM chips on the manufacturing lines developed for standard chips. That has eroded the barriers to bringing PCM out.
Although Philips, IBM, and others have made progress in PCM, only Samsung is close to coming out with chips commercially, Harrison said.
Why will the world want PCM? Performance, says Numonyx CTO Ed Doller. PCM chips can survive tens of millions of read-write cycles, he said, or far more than flash. Reading data to PCM chips takes 70 to 100 nanoseconds, or as fast as NOR flash. Data can be written to the chips at a rate of 1 megabyte a second, or equivalent of NAND flash. There is also no erase cycle, making it similar to DRAM.
In other words, you have the best attributes of three different types of memory--plus, PCM will potentially use far less power.
The cost premium is also coming down fast. By next year, Numonyx hopes to make PCM chips, using 45-nanometer processes, that can hold two bits of data per cell. If that's possible, those chips would compete in price with single-bit-per-cell NAND flash, the memory that's being put into solid-state drives today, said Doller.
But the most important thing is that scientists believe they will be able to increase the density of these chips comparatively easily. In the future, standard flash chips will need additional circuitry for error correction and other functions. Not so with PCM. The smaller the bits get, the less heat that will be required to flip them, Doller added.
"The most important thing is that it is scalable," Doller said.
Intel and ST Microelectronics have come up with a way to put multiple bits of data in a single memory cell in phase change memory, a breakthrough that effectively doubles the technology's density.
Now if they could only get the stuff to market.
Phase change memory is a type of memory made out of materials similar to those used to make CDs and DVDs. A tiny laser rapidly heats up a small bit, and in the process transforms the structure of the bit from crystalline to amorphous. Reversing the process can change the bit from having an amorphous character to a crystalline one again.
A light beam reflects off the bit, and its state (amorphous or crystalline) then gets registered as a 1 or 0, the building blocks of data.
The companies have come up with an algorithm that can assign values to two additional intermediate states. To use an analogy, traditional phase change memory can discriminate between water and ice. Now it can recognize vapor, water, sort of solidified water, and solid ice. The companies are presenting a paper at the International Solid State Circuits Conference on a 256-megabit phase change chip that holds multiple data bits per cell.
The companies have formed a joint venture called Numonyx that is supposed to come out with new types of memories. Numonyx looks suspiciously like Ovonyx, the company that pioneered phase change and licenses technology to Intel and ST. (None of these, however, should be confused with Wyld Stallionz, the band from Bill and Ted's Excellent Adventure.)
Industry sources expected Numonyx to make an announcement last year. It didn't. Intel has talked up phase change as a flash replacement for years, but has yet to release chips. (Gordon Moore even mentioned it back in 1970.) Other companies--Philips, Samsung, you name it--are in the same boat. They have prototypes and plans, but no products yet.
But maybe someday.
Financing has been cut by about half for a partnership by Intel, ST Microelectronics, and Francisco Partners to launch a flash memory company called Numonyx, the companies said Wednesday. In addition, the company, called Numonyx, won't be established until early 2008, under a revised schedule.
Initially, Numonyx was to have received up to $1.55 billion in debt financing. The companies have revised financing terms so Numonyx now has a $650 million loan and $100 million revolving credit facility, Intel said in a regulatory filing with the Securities and Exchange Commission.
STMicroelectronics added in a statement that the companies obtained the new financing after "significant turmoil in the debt capital markets."
The companies had a December 22 deadline to establish Numonyx but have agreed to an extension to March 28, the companies said.
The partners still intend for Numonyx to "hit the ground running" with patents, a independent work force, and well-equipped manufacturing facilities, STMicroelectronics said. "Based on the finalized financing structure, at closing Numonyx is expected to have a similar level of net cash, with lower indebtedness, than originally anticipated," the company added.
Flash memory endows everything from portable media players to high-end laptop computers with data storage space, and its use is on the rise as more devices either have it built in or come with slots that accommodate plug-in flash cards.
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