Specific Process Knowledge/Lithography/EBeamLithography/JEOLAlignment: Difference between revisions

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 =Aligned exposure on JEOL 9500=
-There is quite a few things to remember in order to align an exposure to an existing pattern. The example below is a step by step guide illustrating global substrate alignment as well as chip alignment. If your job only requires global alignment simply skip the chip alignment part.
+There is quite a few things to remember in order to align an exposure to an existing pattern. The example below is a step by step guide illustrating global substrate alignment as well as chip alignment. If your job only requires global alignment simply skip the chip alignment part. In the example we assume a layer, L1, is already defined on the substrate and the goal is to align the next layer, L2, to it.
 ==Job preparation==
-The job illustrated below writes a chip layout in a 5 x 5 matrix into a 2 x 2 matrix as illustrated in the figure. The first layer, L1, has defined global marks at P = (-30000,0) and Q = (30000,0). The local chip marks are placed at M1 = (-450,450), M2 = (450,450), M3 = (450,-450) and M4=(-450,-450).
+The job illustrated below writes a chip layout in a 5 x 5 matrix into a 2 x 2 matrix as illustrated in the figure. The first layer, L1, has defined global marks at P = (-30000,0) and Q = (30000,0). The local chip marks are placed at M1 = (-450,450), M2 = (450,450), M3 = (450,-450) and M4=(-450,-450). First a global alignment is called via the '''GLMDET''' command and subsequently chip alignment is called using the '''CHIPAL''' command. The mark positions are stated in the JDF file using the '''GLMPOS''' command for PQ marks and the '''M1''' to '''M4''' commands for chip marks.
-Chip alignment requires a global alignment to be made first to establish the wafer coordinate system. Hence a global alignment using '''GLMDET''' is used initially as in the example above. To further illustrate chip alignment we will look at a particular layout shown below. The layout also illustrates a commonly used feature on the JEOL system to create arrays of arrays. In the layout below there is main 2x2 array and into each of these is a 5x5 subarray. Each element of the subarray is a single chip with four chip alignment marks. Notice that array placement is given in the substrate coordinate system and so is the global mark positions. Chip alignment marks (M1-M4) are however given in the local chip coordinate system. In the example files below we assume L1 is already defined on the substrate and we wish to align L2 to it.
-Since a pattern (V30 file) is placed at the center of the bounding box it is essential to control the bounding box of the chip design. The design in this case appears symmetric around (0,0) but in order to force it to be symmetric it is common to place corner marks at equidistance points from (0,0). The corner marks can be 1 nm boxes that will not show up in the resist when developed.
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