From joshuar at stanford.edu Tue Apr 8 14:51:38 2008 From: joshuar at stanford.edu (Josh Ratchford) Date: Tue, 8 Apr 2008 14:51:38 -0700 Subject: cancelled reservation. Free until 5pm Message-ID: Sorry, but my wafers will not be ready in time. -------------- next part -------------- An HTML attachment was scrubbed... URL: From rwoo at stanford.edu Wed Apr 9 12:36:14 2008 From: rwoo at stanford.edu (rwoo at stanford.edu) Date: Wed, 09 Apr 2008 12:36:14 -0700 Subject: AMT etcher free today 1800-2000 Message-ID: <20080409123614.9b8a92m7c4s8kk4c@webmail.stanford.edu> Was able to finish earlier in the day. From shott at stanford.edu Mon Apr 14 13:44:13 2008 From: shott at stanford.edu (John Shott) Date: Mon, 14 Apr 2008 13:44:13 -0700 Subject: amtetcher late night problems ..... Message-ID: <4803C21D.5030801@stanford.edu> SNF Lab Members: As a number of your know only too well, the amtetcher often fails to pump down late at night .... typically close to midnight and later. While we do not yet have a fix for this problem, we now have some reasonably convincing data and a hypothesis as to what is triggering this problem. I apologize in advance for the length of this email .... but if you've been plagued by these problems, you may wish to read on. As you are likely aware, the energy costs of a cleanroom are very high and are dominated by the energy required to heat, cool, and move all of the air that makes a cleanroom clean. At normal fan speed there are 7 to 10 air changes per minute in there. To save energy, the fan speed has been reduced starting at 11 p.m. and returning to full speed at 6 a.m. When did that start? I don't know but it has been going on for at least several months. Note: Facilities Operations (FacOps) runs and manages the HVAC system in SNF as well as virtually all of the other building systems. While one would not expect this reduction in fan speed to result in changes in temperature or humidity, we now have data in hand that shows that the temperature near amtetcher drops dramatically by 2-3 degrees C between 11 p.m. and midnight and stays pretty low overnight until the fan speed turns back up at 6 a.m. It also appears as if the relative humidity in that aisle increases by 7-8 percentage points between 11 p.m. and midnight. I have posted these plots outside the cleanroom entrance .... or, if you are curious, send me email and I'll send you the Excel file. Our hypothesis is that significantly lower temperatures and somewhat higher humidity cause the bell jar and the hexode to absorb more water vapor when the bell jar is up and that additional moisture is just enough to keep the system from pumping down below 0.5 mTorr which is close to "as low as it goes" for that pumping package. How can we fix this? At this point, we don't yet have a detailed plan .... we need to look at a few things. Those include: 1. Working with FacOps to understand why the temperature varies so dramatically and work to eliminate the dramatic temperature drop. Note: simply getting the in-lab temperature to better track the temperature set point may not be what we want because the actual set point is very close to the low overnight temperature that causes problems. While simply keeping the fan speed at the daytime setting may seem attractive, that is certainly not the "green" approach in this case. 2. See if we can either increase the temperature or the heat capacity of the hot loop (that is the liquid flow that heats the bell jar all the time and the hexode when the bell jar is open) to better resist moisture absorption. 3. Check to make sure that the pumping system is working optimally. 4. Make sure that the ionization gauge is properly calibrated ... even being off by 0.1-0.5 mTorr could greatly exacerbate this problem. We will keep you posted as we work to resolve this issue, but we wanted to let you know that we believe that we have finally identified what is triggering this strange "time of day" failure. Let me know if you have any questions, John From cearhart at stanford.edu Wed Apr 16 18:24:13 2008 From: cearhart at stanford.edu (Chris Earhart) Date: Wed, 16 Apr 2008 18:24:13 -0700 Subject: AMTetcher reservation released 10am-12pm Thursday April 17 Message-ID: <131c1bff0804161824j634f84c3s13879aab1ed36611@mail.gmail.com> Thanks, Chris From cearhart at stanford.edu Wed Apr 30 11:28:22 2008 From: cearhart at stanford.edu (Chris Earhart) Date: Wed, 30 Apr 2008 11:28:22 -0700 Subject: Reservation removed 1-3 pm today Message-ID: <131c1bff0804301128l4f24ac1egdc7c106cb35215d2@mail.gmail.com> From hweiyin at stanford.edu Wed Apr 30 14:18:30 2008 From: hweiyin at stanford.edu (Serene Koh) Date: Wed, 30 Apr 2008 14:18:30 -0700 Subject: AMTetcher: Reservation removed 4pm to 7pm today Message-ID: <8b7d24450804301418y4e0c34b6qfb79740525f8b54f@mail.gmail.com> Sorry for the late notice.