There has been tremendous progress in industrial laser sources over the past 15 years, particularly in diode pumped solid state lasers. This, combined with improvements in the precision and accuracy of beam delivery and work piece control, is driving many new laser applications in micro-processing. Electro Scientific Industries (ESI) Inc was founded in 1944 in Portland, Oregon, USA, to manufacture high-precision resistance measurement instruments. In the early 1970s , ESI pioneered the development of laser systems for thick and thin film resistor trimming. Since then they have developed many other laser based systems for use in electronics manufacturing.
Laser memory repair
The technique of laser memory repair was co-developed by ESI and Bell Labs in the late 1970s. Since then manufacturers of dynamic random access memory (DRAM) have dramatically shrunk the footprint of individual memory devices. To combat the increasing yield losses that occur as feature size decreases, DRAM chips are produced with redundant rows and columns of memory. Wafers are then probed offline and the data is sent to a laser system which repairs the memory by cutting special laser fuses to remove defective memory and enable redundant memory, see figure 1a. Through this process the yield of the wafer can be improved from <10% to >99.5%.
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