Specific Process Knowledge/Lithography/Aligners/Aligner: Maskless 01 processing: Difference between revisions
| Line 24: | Line 24: | ||
<br/> By measuring the stitching accuracy between two layers printed on the same substrate (without unloading the substrate), we can assess the stage accuracy. By aligning to a pattern previously exposed by the Aligner: Maskless 01, we can assess the mark detection accuracy. And finally, by aligning to a pattern exposed on a mask aligner, we can assess the mask-less aligner's ability to compensate for any scaling and orthogonality errors between the two machines. | <br/> By measuring the stitching accuracy between two layers printed on the same substrate (without unloading the substrate), we can assess the stage accuracy. By aligning to a pattern previously exposed by the Aligner: Maskless 01, we can assess the mark detection accuracy. And finally, by aligning to a pattern exposed on a mask aligner, we can assess the mask-less aligner's ability to compensate for any scaling and orthogonality errors between the two machines. | ||
The results reported here use printed verniers to assess the misalignment along the two axes at different points on the wafer using an optical microscope. Two different designs were used; a ±5µm vernier and a ±1µm vernier. Both consist of a scale of | The results reported here use printed verniers to assess the misalignment along the two axes at different points on the wafer using an optical microscope. Two different designs were used; a ±5µm vernier and a ±1µm vernier. Both consist of a scale of 5µm lines with 10µm pitch, and a vernier scale to enable subdivision of the 5µm or 1µm scale into tenths, i.e. 0.5µm or 0.1µm. During read-out, symmetry enables the observer to measure with ±0.25µm or ±0.05µm accuracy. | ||
>br/>This design is printed in a 1.5µm layer of the positive tone resist AZ 5214E. | |||
==Stitching== | ==Stitching== | ||
In the stitching test, the design consists of ±5µm and ±1µm verniers along the X and Y axis placed in a 3 by 3 matrix covering a 60mm by 60mm area centered on the wafer. The sample is loaded, and the first layer (the linear scales) is printed. Without unloading, the second layer (the vernier scales) are printed on top of the first, and then the sample is developed. | |||
{|border="1" cellspacing="0" cellpadding="3" style="text-align:left;" | {|border="1" cellspacing="0" cellpadding="3" style="text-align:left;" | ||