Chuck Ask your supplier. If this is the Plasma Etch in Carson City, NV, they have as good of handle as any (I think Continental Circuits (AZ?) was their partner for microvias). Otherwise, get an experienced plasma guy to explore your parameters space for a good process. It's not easy. For literature, track down a book called "Plasma Etching-An introduction" edited by Dennis Manos and Daniel Flamm (interlibrary loan). It's a semiconductor book, but the chemistry is the same. For the record, the plasma chemistry is general at best. In general, the O2 plasma is etching to form CO/CO2 gas byproducts while the CF4 component creates some sidewall residue in the form of H2-CF4/CHF3 (the C and the H comes from the polymer). The sidewall residue is used to enhance anisotropy (something present PWB etchers don't do well). Gas pressure (10 mT vs. 0.1mT) makes a huge difference on the overall process (and etch rate, but not as you'd expect intuitively). Nonuniformity across the sample is caused by many issues: spatial and temporal variations in plasma/gas species during etch, poor cathode (sample holder) design in terms of electric fields and gas flow, gas ratio, etc. Because of the limited plasma etch chamber design, there is not a lot of finess you can do. Experiment with gas pressures, gas ratios, and bias. It is not an easy thing to do without help. I would tend to try a low gas pressure (I don't know your system, but well below 1mT), fix the bias, and vary the gas ratio. The low gas pressure bypasses the fluid flow dynamics you'll face at a few mT, but at a cost of a slow process. Once you understand that, increase the pressure (you'll have to limit the current) and repeat in the region you feel works best (but exploring outside the comfort zone). Then adjust the bias and optimize. Odds are, you won't have any time to do the above, but that's how you go about it from scratch. Good luck. If you're lucky, someone here will feel sorry for you and give their recipe away. Carey -----Original Message----- From: Hawkins, Chuck <[log in to unmask]> To: [log in to unmask] <[log in to unmask]> Date: Tuesday, October 19, 1999 1:51 PM Subject: [TN] Plasma etch desmear Looking for technical information on plasma etch. Specifically we are using a Plasma Etch Inc. chamber. 13.56 MHz RF. Etching Arlon 45N. Uniformity of etch is terrible. CF4/O2 gas [log in to unmask] <mailto:[log in to unmask]> 972 603-7202 ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ############################################################## ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################