Archived posting to the Leica Users Group, 1999/01/11
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Alexey Merz alexey@webcom.com wrote: <<...Applied Precision Instruments in Seattle makes steppers with a >>repeatable absolute accuracy of 10 nm over a greater than 20 mm >>range of movement. These units are being used in the semiconductor >>and biotech industries...>> Berg Na <bergna@yahoo.com> responded: >You are comparing micro-actuators which are based on stepper motors >and optical step-and-repeat mask aligners which are also commonly >referred to as steppers. Alexey replies, while donning his asbestos suit, mittens, and shades: Okay. My mistake. >Applied Precision Instruments makes microscopes for live-cell >fluorescence microscopy used for biological diagnostic applications Yes. We just ordered one from them, although It's more accurate to say that it's for research, not "diagnostic" applications. BTW, the API microscopes are great for fixed (dead) cells, too. >which are not even remotely related to the >step-and-repeat masks aligners used in IC fabrication. Except that I was making a point about the precision of manmade devices. In that context, they *are* related. Like, duh. >>API also makes linear actuators (with 10 nm positioning resolution) Which is the core technology of both the API microscopes and (some of) the API semiconductor equipment. And 10 nm resolution is a damn sight better than the ~0.1 um resolution that was being bandied about as a standard of excellence. Yawn. >and probe cards analyzers for the semicondutor industry but again, >they do not make the kind of steppers that Intel uses to build its >Pentiums. Like I said, my mistake. Geez. The correction doesn't invalidate my main point, though. <<So I'd have to say that AFM's are by far the most precice pieces of >>equipment yet made by mankind; they allow the movement and placement >>of single atoms, and put the best UV photolithography to shame.>> >There are simply no basis for comparison between AFMs which are >basically high resolution microscopes and steppers which are used to >project microscopic images with absolute fidelity. First of all, I was drawing a comparison between the working precision of different manmade devices. AFM's are certainly the most precise devices yet fabricated by humans. Ergo, I say the comparison has a solid basis. Let the reader decide. Second, AFM's are NOT "basically high resolution microscopes" as they can probe *many* properties of an object, including electical and mechanical properties. What's more, AFMs can be used (as I already pointed out) to manipulate, move, and place on substrates single molecules or even single atoms. They are not simply passive viewing devices, as you (parhaps not intentionally) imply. Third, there is no such thing as "absolute fidelity", except in our dreams. Someone who appears to know more than a bit about microfabrication might not wish to use such absurd terminology, for fear that it might make him look silly. Fidelity can be adequate, but cannot be absolute. .......................................................................... Alexey Merz | URL: http://www.webcom.com/alexey | email: alexey@webcom.com