Copyright 2007 by Raith GmbH Adjust and Align Stage Adjustment & Writefield Alignment

Copyright 2007 by Raith GmbH Adjust and Align 2 Motivation You surely have an idea where you want your pattern to be exposed on your sample. But do you also have an idea about how you can realize it?

Copyright 2007 by Raith GmbH Adjust and Align 3 Overview This presentation will explain  Types of Coordinate Systems  Adjustment Procedures  Positionlist Navigation  Writefield Alignment Procedures

Copyright 2007 by Raith GmbH Adjust and Align 4 Types of Coordinate Systems  StageX,Y  SampleU,V  Designu,v  Beamu,v

Copyright 2007 by Raith GmbH Adjust and Align 5 What happens, if I do not care about „Adjust“ and „Align“? X Y U V Types of Coordinate Systems

Copyright 2007 by Raith GmbH Adjust and Align 6 X X X What happens if I do not care about Adjust and Align?

Copyright 2007 by Raith GmbH Adjust and Align 7 How do I link sample and stage? Adjustment Procedures X Y U V

Copyright 2007 by Raith GmbH Adjust and Align 8  Aim create your own coordinate system on a bare sample referring to your needs  define an origin  determine a rotation angle  Reason sample is rotated and shifted compared to stage axes  Result stage: XY coordinates sample: UV coordinates rotation Adjustment Procedure: Bare Sample shift between origins

Copyright 2007 by Raith GmbH Adjust and Align 9  Aim link into an existing coordinate system  use design markers and relate their UV design coordinates to XY coordinates of the stage  software calculates zoom, shift and rotation values  Reason pattern might be zoomed, rotated or shifted referring to design coordinate system  Result ability to move stage in design coordinate system Adjustment Procedure: Structured Sample  Create local coordinate system  Result:  global adjust UV for sample  local adjust UV for pattern  Keep both coordinate systems!

Copyright 2007 by Raith GmbH Adjust and Align 10 How do I define the position of my pattern on the sample? Positionlist Navigation X Y U V

Copyright 2007 by Raith GmbH Adjust and Align 11 Positionlist defines placement of pattern in sample coordinate system (UV) UV coordinate in positionlist is always center of first stitchfield working area = design portion used for exposure and separated into stitchfields Positionlist Navigation Working area has to be defined

Copyright 2007 by Raith GmbH Adjust and Align 12 Positionlist: Definition of Working Area

Copyright 2007 by Raith GmbH Adjust and Align 13 How can I be sure that my beam deflection fits to my purposes? Keyword: stitching Writefield Alignment X Y U V

Copyright 2007 by Raith GmbH Adjust and Align 14 How is the beam supposed to know where to deflect to get the results I want?  Writefield alignment necessary  relate beam deflection to a reference  determine zoom, shift and rotation values for deflection  Dimension and orientation of the pattern must fit to the purposes How can I get that setting? Writefield Alignment

Copyright 2007 by Raith GmbH Adjust and Align 15 Two possibilities dependent on stage Without laser stage: reference sample Chessy With laser stage: stage movement as reference Writefield Alignment Existing pattern with markers as reference Third possibility independent of stage

Copyright 2007 by Raith GmbH Adjust and Align 16 Use structures with known dimensions to calibrate deflection: minimum size / resolution = 1 µm + Allocate centers of scan areas with well defined distances to markers on chessy sample with same distances Writefield Alignment: Chessy Calibration stage position

Copyright 2007 by Raith GmbH Adjust and Align 17 Numerical resolution of laserstage: 2 nm Laserstage can be used as calibration standard Procedure:  move a particle into the center of your SEM screen  stage drives into corners of the writefield (particle also moves)  beam is deflected to those corners  shift between supposed particle position and real particle position is measured  measurement is done for 3 positions  zoom, shift and rotation for writefield alignment will be calculated Writefield Alignment: Laser Stage Calibration

Copyright 2007 by Raith GmbH Adjust and Align 18 Writefield Alignment: Laser Stage Calibration

Copyright 2007 by Raith GmbH Adjust and Align 19 Writefield Alignment: Mark Recognition Applications:  Overlay  Mix & match  Gate in HEMT structure Procedure:  Arrange manual or automatic mark recognition in your GDSII design (predefined layers 63 or 61)  Alignment will be done during exposure task  Alignment will be checked before overlay exposure takes place Result:  Optimum values for high accuracy

Copyright 2007 by Raith GmbH Adjust and Align 20 Procedure: Stage drives to center of WF and stays there during the whole procedure Writefield Alignment: Mark Recognition  Manual (layer 63): Imagescans with manually applied corrections (similar to Chessy calibration)  Automatic (layer 61): Horizontal and vertical linescans (intensity / contrast detection) with detection filter

Copyright 2007 by Raith GmbH Adjust and Align 21 Writefield Alignment: Mark Recognition Setup is similar to standard exposure

Copyright 2007 by Raith GmbH Adjust and Align 22 How can I link the coordinate systems?  Adjust: create sample coordinate system  Positionlist: determine pattern position on your sample  Align: calibrate beam deflection Summary X Y U V

Copyright 2007 by Raith GmbH Adjust and Align 23 Result High stitching and overlay accuracy