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October 13, 2008

DI Water Resistivity

What is the DI Water resistivity needed during wafer dicing? We are using a CO2 Bubbler maintaining water resistivity is at 0.5 to 1.0 MOhm-cm. How much time will it take to damage the processed unit if the resistivity goes beyond the range? Will it damage the unit if it is more than 1.0 MOhm-cm? How about below 0.5 MOhm-cm?

N.L.P.

Expert Panel Responses

To answer your question, the better the water quality the less garbage you put on your wafers. Why only 0.5 1.0 MOhm-cm why not higher? We have successfully used 10 MOhm-cm or better to dice wafers but more importantly we have low silica levels. At times when the solubilized silica in the water systems from your local water treatment plant are high you will coat the bond pads with this soluble silica and make bonding difficult or impossible at times. So better water quality also minimizes the amount of chloride, fluoride, sulfate, sodium and ammines as well as any silica, or particulate debris.

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Terry Munson
President/Senior Technical Consultant
Foresite
Mr. Munson, President and Founder of Foresite, has extensive electronics industry experience applying Ion Chromatography analytical techniques to a wide spectrum of manufacturing applications.