Today we filled an order for graduate student Shwetadwip Chowdhury and his research team (Jeff Chen et al) at the Biomedical Engineering department at Duke University for a custom mask design. They were looking for a grating mask to serve as the structured pattern for exploration of structured illumination microscopy for subdiffraction resolution imaging. The critical dimension (CD) of the grating needed to be 0.5um or less with uniformity of 10nm. Since the smallest CD we offer as a standard product in our store is 1um, they submitted an RFQ for a custom mask. We were able to offer the research team a mask with a 0.125um CD and 10nm CDU but the cost exceeded their budget. So instead we presented a solution with their desired CD but a relaxed uniformity (50nm) that was within their budget. Moreover, we laid out the mask for them in such a way that they get four desired rotations without rotating the mask, by simply translating in X and Y instead. You can take a look at the product in our store here and read more about the research here.
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I received this message today from Kelvin Liu, CEO of Circulomics:
March Madness is a great month for college basketball fans. It's also a great month for LITHOGRAPHERS as you can get 5% off your photomask purchases all month long at PhotomaskPORTAL. Use coupon "MarchMadness" at check-out and enjoy the month of March.
PhotomaskPORTAL is proud to now offer LayoutEditor software by Juspertor. LayoutEditor is great software for applications such as MEMS, ICs, PCBs, Microwave, and many more. It feels easy to use but offers sophisticated functionality including schematic-driven and parametric layout, design rule checks, boolean operations, font generator, and can handle all angles. It has powerful automation capability with C++ macros and python scripting. It supports a wide range of file formats including GDSII, OASIS, OpenAccess, DXF, CIF, Gerber (RS-274X), LEF, DEF, Lasi, SOURCE and many more. The LayoutEditor runs on Windows, Linux, or Mac OS X and can easily be ported between platforms, depending on where your work takes you. Depending on your particular needs, there are several versions available from full-featured to a basic viewer. Read more about this versatile software in our STORE. Let us know if you like to try before you buy. Industry veteran Brian Grenon shares his thoughts on the evolution of the photomask industry and when -- if ever -- the industry will move to larger photomask formats. Right-reading, wrong-reading, through-the-glass, chrome-up, chrome-down, digitized-data dark, digitized-data clear, tone reversal, wafer view, reticle view, parity, polarity, ... there's a lot of terminology to keep straight when defining how to build a photomask. But it all comes down to answering these two basic questions:
Most photomask are used mask-side down, or "chrome-down" if the absorber is chrome. While this is obvious for contact lithography, for projection optics the reason is simple enough -- after you use a mask to modulate light into an aerial image, you don't want to send this precious image back across the photomask substrate, losing resolution and intensity along the way. No, you want to feed this directly into your high-NA stepper optics designed to capture the high spatial frequencies diffracting off your mask. For this reason, most photomask patterns are mirrored before they are written onto the mask. The mirroring can be done either during dataprep or on the write tool.
The other key question is what tone to make the polygons in your design data. In theory a maskshop can choose between a positive photoresist and a negative photoresist depending on the answer. In practice the maskshop will standardize on one type of photoresist and reverse the tone of your data as needed. Most photomasks with features of a micron or larger are written with positive photoresist. This is perfect if you want your polygons to be clear but means the maskshop will reverse the tone of your data when you want the polygons to be dark. Node after node, creative use of photomasks with refractive optics continue to delay the arrival of Extreme UV lithography based on reflective optics. Using a wavelength that is more than an order of magnitude smaller than ArF, all photomask substrates become opaque with EUV. A photomask changes from modulating light passing through it to modulating light reflecting off it. Cool stuff ... if it ever gets here. If you're intrigued by the status of EUV, this is the conference for you:
In perhaps the biggest news in the photomask industry in years, DNP and Photronics will join operations in Taiwain in a new joint venture (PDMC). Link
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