![]() ![]() In relatively large structures provided as part of a semiconductor wafer, such as hemispherical bumps having a diameter of around 100 μm, errors due to the presence of partially transparent layers of passivation or resist surrounding and/or supporting the bump can make it difficult to measure the height of such a bump from its base to its top. While measurements using light can be and are quite accurate, variability in the materials used to form the IC device can introduce error into the measurements. Even this can be challenging where the physics of light impose variability on the measurements themselves. Accordingly, measurements on an integrated circuit (IC) device are made relative to other features. Semiconductor substrates and the structures formed thereon (sometimes collectively referred to as a semiconductor wafer) are themselves work pieces and are actively being modified during a fabrication process. Few such reliable references exist in the semiconductor field where measurements are made using light. Machinists use precision ground granite or cast iron surfaces as a reference. Obtaining a useful measurement relies, in large part, on having a reliable and consistent reference. 6, 2017, entitled “LASER TRIANGULATION CALIBRATION” and is incorporated herein by reference. This application is a PCT Application that claims priority to U.S. ![]()
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