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Ma. Aisa Aceremo, Edgar Rectitud, Jojo Florendo, Orient Semiconductor Electronics Phils., Inc.
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Deionized (DI) water, which is used at wafer saw to cool down the dicing blades and provide some washing action, is insulative in nature, and can result in static charge build-up that can damage ESD-sensitive devices. This is why a lowered water resistivity at wafer saw is desired if dealing with ESD-sensitive devices. In this study, the lowering of the water resistivity to customer specifications was achieved by a reionization process that involves the injection of carbon dioxide gas into the DI water. This solution, however, led to other problems, namely, kerf weaving and early blade breakage. The authors attribute these problems to the confounding effects of water impingement on the blade, impact of unconstrained silicon dust on the blade which causes premature release of the blade's diamond particles, blade exposure vibration, and frictional heating. Nickel corrosion by carbonic acid, however, was disproved. The authors recommended the use of new dicing blades designed for lower-resistivity water and implementation of relevant wafer saw process controls when dicing ESD-sensitive IC's under low-resistivity conditions. |
