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By Leanne Schmidt, Dynatex International, Santa Rosa, Calif., [dynatex.com] and Doug Pulfer, J P Sercel Associates Inc., Hollis, N.H., [jpsalaser.com]
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| Although the traditional dicing saw continues to be the mainstream production tool for singulation, scribe-and-break systems are gaining favor among both manufacturing and process engineers. |
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| Figure 1. A 2.5µm-wide kerf in a sapphire substrate |
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| Figure 2. A scribed GaAs wafer after break-and-stretch |
Constant advances in semiconductor designs and materials continue to challenge engineers to find economical ways to singulate parts.
Delicate MEMS devices, the demand for ever-smaller packages and expensive III-V materials have driven demand for equipment that can singulate today's semiconductor materials quickly and efficiently.
Scribe-and-Break Technology
While the traditional dicing saw continues to be a mainstay production tool, more and more process and manufacturing engineers are turning to scribe-and-break technology to solve difficult production problems.
Frequently, the tool of choice is a diamond scribe, laser-based scribe or a saw- scribe combined with a breaking process. (Two examples of laser scribing are shown in the figures.)
Increased Use of Laser Tools
Recent advances in the power and reliability of UV lasers have resulted in the increased use of laser tools for wafer scribing.
Device manufacturers are attracted by the heat-free attributes of the current generation of short wavelength, high-repetition-rate lasers. Moreover, the narrow streets produced by the laser allow closer spacing of devices, boosting productivity by maximizing the use of expensive wafer real estate.
Modern wafer-breaking technology can also handle the needed amount of precision with ease. Available tools, for example, employ several different breaking mechanisms suited to the characteristics of different substrates.
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| Recent advances in the power and reliability of UV lasers have resulted in the increased use of laser tools for wafer scribing. |
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Wafer Breaking is Material-Dependent
The wafer breaking process depends more on the material than on the scribing method.
Scribing systems and breaking systems are available with fully automated wafer-handling capabilities.
For manufacturers using high-resolution laser-scribing methods, the smaller die and narrower streets (350µm x 350µm or smaller die with 10µm wide streets) pose no difficulty to current high precision wafer-breaking systems.
Decisions on whether to use diamond scribing, laser scribing or saw-dicing techniques, whether for III-V or II-IV materials, sapphire, silicon or other substrates depend, as usual, on balancing throughput and yield, as well as the cost of the tool and consumables.
Conclusion
While traditional saw dicing is a tried and true production method, the rapid advances in scribe-and-break technology continue to open new opportunities for design and process engineers in today's rapidly developing semiconductor market.
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