LED 150mm: Is this an important inflection point?
A lot more news has been published recently about large LED wafer production. LEDs Magazine reported that Philips Lumileds and Lextar Electronics are now running production on 150-mm wafers and that there is another un-named Asian company using 150-mm sapphire wafers supplied by Rubicon Technology. Rubicon also recently announced the availability of 300-mm Sapphire wafers for LED production. All this makes me think that this is only the first wave in what will be a deluge of announcements for large wafer size production in LED.
These announcements got me thinking about the technology that will be required to support production on these larger size wafers. Is there something small wafer manufacturers can leverage to derive some of the benefits of the larger wafers before they actually transition to these in their factories?
First, there is a lot more at stake with the larger diameter substrates. A single scrapped wafer could create an order of magnitude, more wasted LEDs then on a smaller substrate equivalent. Additionally, manual loading and unloading of wafers by people with tweezers is unrealistic with big wafers. The risk is just too high.
Companies moving to the larger substrates are likely moving towards more automation as well. As was the case with semiconductor manufacturing, material handling, tracking and control are likely to become even more important in these environments to drive quality and throughput and to further drive down costs. An example of further cost reduction might be a more sophisticated preventive maintenance schedule that not only considers run time and chemical use, but also considers the current tool performance and metrology data.
Does this mean the demise of all smaller LED substrates? I doubt that the LED world will scramble to upgrade to larger wafers as fast as semi manufacturers did. The processing expertise for sub-5 inch wafers is well established, and continues to be refined every day. And while the larger substrate processing focuses on yield improvement, the small wafer producers have a chance to further improve their bin yield through advanced process control on various tools in their production environment. Technologies like Fault Detection and Run to Run Control can further boost the yields on the important and high value parts, so they can continue to produce batches with the high value output that rivals even the largest substrate sizes. And the cost cutting, preventative maintenance example used above is certainly applicable to smaller substrates as well.
Adding specific software technologies to small wafer size production lines will give manufacturers a good chance to remain highly competitive in the short term, and for many more years to come. Certainly it would allow more time to transition to larger substrate sizes and help master Advanced Process Control to begin leveraging their experience with the larger wafer sizes as they are ramping.