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Technology Stocks : MEMC INT'L. (WFR -NYSE) The Sleeping Giant? -- Ignore unavailable to you. Want to Upgrade?

To: J L Segal who wrote (2917)	1/14/1998 7:05:00 PM
From: olduvai5	Read Replies (2) \| Respond to of 4697

JL, in answer to your question, imagine a dirt road freshly graded with a saw tooth blade. This, in gross exaggeration, is a prime wafer. The polishing process, fine as it is, leaves numerous surface flaws and marks. To make high end chips, the surface is critical. Back to that dirt road. Now, let's add a layer of asphalt comressed by a 30ton steam roller. This is the epi layer. It fills the flaws and creates a uniform surface for the impression of the base structures of the device being manufactured. Most processors and DRAM of 16MBit and up is now done on epi wafers because the greater uniformity of surface gives much higher yields per unit area. As we move to smaller and smaller chips with finer and finer feature size, the base grows in importance. Growth in the demand for epi is predicated on the assumption that surface preaparation techniques will not be able to advance fast enough to compete. This assumption may be flawed. New methods of chemical mechanical planarization are nearing commercial deployment. Though unproven on the production floor, they may yet give epi a run for the chip makers' money. olduvai5 PS sorry for the oversimplification, but I just gave that lecture to my daughter and I couldn't resist!