Feature: Sensors


input and so perform a synchronous measurement. In order to measure the high number of chips and their bumps in the shortest possible time, Micro-Epsilon sensors off er measuring rate of 70kHz. Confocal chromatic sensors from


Micro-Epsilon are used to detect cracks, saw marks and other defects on the wafer. T ey reliably detect surfaces with varying refl ection characteristics due to a high- speed surface compensation feature. An extremely small light spot and high resolution enable the reliable detection of the fi nest of anomalies on the wafer. T e larger the wafer, the greater the risk


Figure 12: Confocal chromatic sensors scan the wafer surface to detect bow, warp and distortion


of defl ection. Confocal chromatic sensors scan the wafer surface to detect bow, warp and distortion; see Figure 12. With a measuring rate of 70kHz, the confocalDT controllers enable highly dynamic measurements, allowing inspection in short cycle times. For total thickness variation, two


confocal chromatic sensors measure the wafer thickness from both sides. T e thickness profi le of the entire


wafer can also be used to determine the curvature and defl ection of the wafer. High measuring rates enable thickness detection of the entire wafer in short cycle times.


Figure 13: Precise edge detection of wafers using laser micrometers


high measurement rate is also required to support high-speed manufacturing processes. Confocal chromatic sensors are used


for one-sided thickness measurements of layers. T e confocal measuring principle enables the evaluation of several signal peaks, allowing the thickness of transparent materials to be determined. Using multi-peak measurement, even the thinnest layers are reliably detected. With just one sensor, the thickness of protective and paint layers, for example, are detected


with micrometer precision. Confocal chromatic sensors from


Micro-Epsilon measure precisely on shiny and textured wafer surfaces to determine the height of bumps with micrometer accuracy. Due to the focused light spot, high lateral resolution of 4µm is achieved. In this measurement task, three sensors


are moved above the wafer. From the three tracks, both the spherical shape and the height can be calculated precisely. T is is possible because the controllers are connected via Ethernet and trigger


38 February 2023 www.electronicsworld.co.uk


Wafer handling T roughout the manufacturing process, wafers must be automatically removed and fed to the appropriate processing step. Accurate positioning is just as important as fast, reliable movement; see Figure 13. Also, when handling wafers, exact and


repeatable positioning is crucial. During the infeed of wafers, two optoCONTROL laser micrometers from Micro-Epsilon inspect the diameter and thus determine the horizontal position. Due to their high measuring rate and accuracy, these micrometers provide reliable position information. When feeding wafers, white light


interferometers are used to measure their horizontal tilt. T e interferometers provide absolute distance values at nanometer resolution, ensuring the greatest possible positional accuracy when picking up and removing wafers.


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48