LONDON – Mike Bryant, technology analyst with Future Horizons Ltd. has said that foundry Taiwan Semiconductor Manufacturing Co. Ltd. is in trouble with its 28-nm manufacturing process technologies, which are not yet yielding well. Bryant referenced un-named contacts made with multiple companies waiting for designs to be produced by TSMC on 28-nm processes.
Bryant said that there are 10 designs in manufacture from seven companies. "We're now hearing none of them work; no yield anyway," he told an audience at a one-day market forecast conference organized by Future Horizons, here on Thursday (Jan. 19). "Ten designs going through; we have heard about problems on six of them," Bryant added. Bryant's comments echo those made by Bob Johnson, research vice president at market research firm Gartner in November 2011.
However, Bryant's description of the situation at TSMC is quite different to that of the company's CEO and chairman Morris Chang. Speaking to analysts about TSMC's fourth quarter financial results on the previous day, Chang said: "Our 28-nm entered volume production last year and contributed 2 percent of 4Q11's wafer revenue. Defect density and new progress is ahead of schedule and is better than 40-45-nm at the corresponding stage of the ramp-up. We expect 28-nm ramp this year to be fast and we expect 28-nm will contribute more than 10 percent of total wafer revenue this year."
Nonetheless Bryant of Future Horizons asserted that Intel has a clear technology leadership position as it has been running 32-nm manufacturing process for some time and that pressure to keep up with Intel had caused some miss-steps by TSMC, while Samsung Electronics Co. Ltd., with experience gleaned running 20-nm class memories, had successfully brought up its 28-nm low power logic process.
In contrast, TMSC is in a similar situation to Globalfoundries Inc. which saw problems with its 32-nm/28-nm processes in 2011 that appeared to drive its primary customer, Advanced Micro Devices Inc., towards TSMC as a source of integrated circuits. Bryant acknowledged that the TSMC 28-nm process is now in true volume production and the Qualcomm Snapdragon S4 has won the highest proportion of available design slots. "However, there are recent comments of major yield problems with their 28-nm process actually being even worse than at GF [Globalfoundries]," Bryant told the audience.
Intel's lead in process technology has put foundries under pressure, Bryant said. The 18-month to two-year time scales needed to develop processes, and design complex ICs mean that both are being begun before the other is completed and stable. While that process can be managed in-house by an IDM such as Intel, foundries are finding it more difficult as they have to work with customers on chips and physical design kits at the same time.
Regardless of the truth of the details, 28nm has been a real challenge, particularly in the initial ramp up phase. This is more sanely evidenced in the increasing amount of DFM activities being pushed to the designer at these nodes. Things like litho checking, smart fill, pattern based checks, and restricted design rule checks have migrated from recommended to required. This is evidence enough that many of the second and third order effects on yield are becoming first order. Strict adherence and effort spent optimizing these DFM issues in the design phase is probably what is causing such different results on different chips. All designs are not the same from a DFM perspective.
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