by Bob Haavind, editorial director, Solid State Technology
May 20, 2008 – Achieving significant productivity and cycle-time improvements in next-generation factories (NGFs) will require industrywide collaboration in cutting waste, particularly through “shared visualization,” according to Shigeru Kobayashi, chief engineer for Renesas in Japan, at a Confab NGF panel session.
Kobayashi is working with the Japan Electronics and IT Industries Association (JEITA) on a J300P guidelines NGF document. This will be a successor to the current 300C aimed at providing stepwise improvements over the next few years.
As an illustration of the visualization approach to cutting what Kobayashi called “Dandori” waste, he showed the results of a set of processing runs on a PVD (physical vapor deposition) tool for five lots of 40 wafers. Each process step was color-coded, and the processing was monitored from a wafer view, rather than the conventional lot view. The times for each step were stacked in color-coded bars, which showed wide variation in total processing time over many runs. Kobayashi explained that this approach enables an examination of wasted time in Dandori inputs, which are steps such as a setup after a wafer change rather than factors such as seasoning maintenance. This chart allowed shared visualization of the variation with the tool vendor. This supplier then made improvements to the equipment and the run was repeated. The resulting chart showed much more stable tool operation. This improvement resulted from the shared visualization, Kobayashi concluded.
These methods have also identified some other areas of waste. If lots cascade there will be excess waiting time while previous lots are processed, for example. It was also found that waste can be greater in three loadport operations. Studies showed that 25-wafer lots were more efficient than 12-wafer lots, and that JIT (just-in-time) delivery is critical.
In order to tackle issues like this, Kobayashi stated, industry consensus is needed on how waste is to be measured.
Right now, this is not being done very well by devicemakers, he said. It is important to get from equipment makers information such as intended maintenance times. Then performance can be measured vs. intended times.
Visualization quality also needs to be improved to help achieve EEQA (enhanced equipment quality assurance), he said.
“It is urgent to establish industry consensus on shared visualization,” Kobayashi concluded, “followed by standardization of waste information exchange.”
This can lead to shared visualization and systematic waste reduction, he added. That would help meet the need for data infrastructure development in preparation for much more productive, shorter cycle-time, next-generation factories. — B.H.