Specific Process Knowledge/Lithography/EBeamLithography/JBX9500Manual: Difference between revisions
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After finished exposure, the machine will display whether the exposure succeeded. | After finished exposure, the machine will display whether the exposure succeeded. | ||
= Alignment of | = Alignment of exposure to existing pattern on wafer = | ||
If you need to align an exposure to an existing pattern on a wafer you need wafer marks (or global marks) to align your exposure to. If you are exposing chips (i.e. many small GDS-files you repeat in a matrix), chip marks is recommended to align every chip. | |||
'''Please note that manual alignment (using the SEM) is not allowed.''' You should use semi-automatic alignment only. In rare cases where semi-automatic alignment is impossible, you should remove the resist around the wafer marks before loading the wafer/chip into the machine. | |||
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| [[File:mark example2.png|100px]] | |||
| [[File:GlobalMark.png|120px]] | |||
| [[File:P Q marks and chip marks.png|250px]] | |||
| [[File:Chip example.png|150px]] | |||
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| Definition of length and width of global mark, use L = 500-1000 µm, W 3-5 µm || Text around mark not recommended || Global mark (P and Q) positions on wafer. Positions of global marks are entered in jdf file using wafer coordinate system. || Example of chip with 4 chip marks. Always position the chip marks outside the chip pattern. Position of chip marks are entered in jdf file using chip coordinate system, i.e. center of chip is (0,0). | |||
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'''1 Material:''' Global marks or chip marks should be clearly visible in a 100keV SEM, i.e. preferably defined by Ti/Au or another 'heavy' metal, alternatively the wafer marks should be etched. In Si, etched mark should be around 1 µm deep in order to be detectable by the machine. Shallow etched (even 200 nm etched profiles) global marks or global marks in Si or marks defined by a light metal as Al can be hard to locate manually as well as automatically by the machine. | |||
'''2 Design: ''' | |||
* Global marks: You need at least two wafer marks, a P mark and a Q mark. It is recommended to have many P and Q marks available on the wafer to choose from. The x-coordinate of the P mark should be smaller than the x-coordinate of the Q mark. The global marks should either be crosses or L-shaped, they should be as narrow as possible and 500 - 1000 microns in length. If the wafer contains a number of identical marks, the marks should be marked in order to identify the 'right' alignment mark (the scan width of the SEM is 1 mm x 1 mm). Text around the wafer mark is NOT recommended. Wafer marks formed as crosses with lengths of 1000 microns and 3-5 microns in width are recommended. | |||
* Chip marks: Prepare 1 or 4 chip marks on every chip. The chip marks can be smaller than global marks, as only very fine alignment is performed with chip marks. The chip marks should either be crosses or L-shaped and text around the marks is NOT recommended. | |||
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