Fixed Beam Moving Stage using a stitching free exposure strategy

2 contents  What is FBMS and how does it work?  How do I create structures for this exposure mode?  How do I expose?  results and applications FBMS

3 Stage propagating direction stage travels at constant speed along (curved) paths of any length and shape with stationary beam  avoids stitch field boundaries  effective for extended paths A. Spot Mode = FBMS line B. Shape Mode = FBMS area Stage propagating direction constant dose circle symmetric What is FBMS and how does it work? FBMS

4 What is FBMS and how does it work? FBMS comparison of current value and ideal value ideal value (starting point, end point, speed) current value (measured by laserinterfero- meter) difference? continue correction signal to column noyes

5 technical note: difference between mechanical motion and ideal path compensated by additional beam deflection (special motor control unit) Layout What is FBMS and how does it work?

6 beam current stage speed * calculation width FBMS area dose= dose is defined as charge per area: calculation width =design width speed electrons=charge FBMS line dose= beam current stage speed FBMS single pixel lines use the following definition: FBMS

7 How do I create FBMS structures? GDSII has to contain special FBMS-elements FBMS

8 How do I create FBMS structures? FBMS structure is defined by nodes and their coordinates comparable to standard GDSII- elements: dose factors, structure widths and layers can be defined width definition determines if FBMS element will be exposed as area or line FBMS

9 How do I create FBMS structures? standard GDSII area FBMS elements can be converted from standard GDSII designs layer selection for converted element FBMS

10 How do I create FBMS structures? FBMS element Example: Optical Waveguides type: start type: line type: arcnext element coordinates curvature  See Software Reference Manual for additional information!

11 How do I expose?  FBMS-Alignment necessary → as motorcontrol creates a correction signal in order to correct stage inaccuracies, the deflection signal has to be calibrated (comparable to align writefield procedure)  Scan Manager offers special procedures FBMS

12 How do I expose?  press „preset“ button to get same values as for align writefield as starting values  FBMS-Alignment works the same way as the writefield alignment: stage moves to corners of the writefield beam is deflected to the same corner to scan an image: deflection is not adressed by pattern generator but by motor control image shift from ideal position is determined FBMS

13 How do I expose? FBMS

14 How do I expose?  after FBMS alignment procedure correction values are determined → as motorcontrol can only correct zoom and rotation these correction values are written into Align FBMS window →shift correction is written into Align writefield window as pattern generator directly applies this shift  FBMS alignment parameters are not stored in an ini file FBMS shift zoom & rotation

15 How do I expose? FBMS elements have to be selected in the exposure window (comparable to selection of SPLs or dots) only if FBMS elements are selected the referring tab for the parameter calculation will be visible FBMS

16 How do I expose? value which has been read in by „current“ window (automatically written) clearing dose for the referring structure (has to be typed in) assumed structure width for speed calculation (determined in „details“) calculate necessary stage speed (has to be calculated by pressing button) FBMS

17 How do I expose? FBMS

18 How do I expose? tab for FBMS area exposure → beam makes circular deflection to create designed structure width effective stepsize for circular beam deflection perpendicular to stage movement user can work with comparable values as for standard GDSII areas calculation width necessary for stage speed calculation →software calculates basic speed during exposure calculation width is adapted to design width and speed is recalculated so that dose is kept constant calculation width= minimum design width: basic speed is maximum possible speed for this pattern width should fit to design but will be adapted anyway calculation of maximum writable structure width (only 3400 points within circular deflection possible)→ restriction calculation of deflection cycle time FBMS

19 < 8 nm Line width = 30 nm Pitch = 100 nm stitching error < 20 nm former results with conventional stitching application examples FBMS

20 Line width = 20 nm Pitch = 50 nm new results with FBMS no stitching errors! no settling time from stitching! application examples FBMS

21 typical FBMS applications are extended (curved) paths  with a length several mm or cm  with a fixed width in the range of 20 nm to 20 µm  where stitching errors are crucial for the performance of the device  where a large number of stitching borders would result in long exposure times FBMS applications in general FBMS