Nano-imprint lithography (NIL) has proven to be a powerful and cost-efficient technology for proto-typing but also the high-volume manufacturing of AR/VR/MR devices and Metalenses. It has the ability to create high-quality replicates of various types of features. These range from small and arbitrarily shaped meta-atoms (e.g. circles, squares, rectangles, diamonds etc) to waveguide gratings used for light transfer in AR/VR/MR devices. However, the latter mentioned gratings are typically not only gratings of vertical patterns. Their application as waveguides requires them to have different, nonvertical shapes such as slanted, blazed or staircase-like pattern. In addition, the duty cycle and the depth of the patterns throughout a grating may vary. All of these patterns need initially to be created on a stamp, the imprint master.
We have successfully demonstrated that these special requirements can be accomplished on nano-imprint masters.
In this paper we will show the variety of Quartz etch technologies that are used for manufacturing of pattern on masters. This ranges from plasma etching, in combination with multi-level e-beam exposure to created staircase like gratings or 3-dimensional patterns (e.g. pyramids). Another technology is ion-beam etching of Quartz in combination with a tilt of the substrate. We will demonstrate how this can be used to create slanted patterns in gratings. This can also be combined with a non-linear variation of etch depth throughout such a grating.
The manufacturing capabilities shown here are a substantial enabler of the technologies required for AR/VR/MR devices, Metalenses and other applications requiring such profiles on an imprint master.
In a first section, we compare the CDC technique with scanner dose correction schemes. It becomes obvious, that the CDC technique has unique advantages with respect to spatial resolution and intra-field flexibility over scanner correction schemes, however, due to the scanner flexibility across wafer both methods are rather complementary than competing. In a second section we show that a reference feature based correction scheme can be used to improve the CDU of a full chip with multiple different features that have different MEEF and dose sensitivities. In detail we will discuss the impact of forward scattering light originated by the CDC pixels on the illumination source and the related proximity signature. We will show that the impact on proximity is small compared to the CDU benefit of the CDC technique.
Finally we show to which extend the reduced variability across reticle will result in a better common electrical process window of a whole chip design on the whole reticle field on wafer. Finally we will discuss electrical verification results between masks with purposely made bad CDU that got repaired by the CDC technique versus inherently good “golden” masks on a complex logic device. No yield difference is observed between the repaired bad masks and the masks with good CDU.
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