Specific Process Knowledge/Lithography/EBeamLithography/EBLProcessExamples: Difference between revisions
No edit summary |
|||
| (10 intermediate revisions by the same user not shown) | |||
| Line 1: | Line 1: | ||
=Mix-and-match with EBL and UV lithography= | =Mix-and-match with EBL and UV lithography= | ||
Using mix-and-match it is possible to combine EBL and UV lithography using selected resists. Read more on the [[Specific_Process_Knowledge/Lithography/Mix-and-match|Mix-and-match page.]] | Using mix-and-match it is possible to combine EBL and UV lithography using selected resists. Read more on the [[Specific_Process_Knowledge/Lithography/Mix-and-match|Mix-and-match page.]] | ||
| Line 36: | Line 34: | ||
'''SHOT S, 550, 0, 600''' | '''SHOT S, 550, 0, 600''' | ||
== | ==Single big box approach== | ||
In this approach the mask is a single box determining the area of the array. The algorithm that places beam shots will seek to fill the shape as evenly as possible. Hence, the shot placements will not form an equidistant grid unless the size of the shape allows an integer number of beam shots to be placed in both axis. This is is illustrated below. To obtain a perfect grid the shot pitch must match both the subfield size and the total shape size, in the sense that an integer number of beam shots should be placed inside each subfield and an integer number of subfields should be placed inside the total shape. | |||
== | By default the subfield size is 4x4 µm. This will match for instance a beam pitch of 200 nm, since it will place 20 beam shots along each axis. It does not match a beam pitch of 190 nm for instance, since 4000 nm / 190 nm = 21.05. If one wants a beam pitch of 190 nm the subfield size should be changed to 3.990 x 3.990 µm. This is done in the JDF file by changing the '''SPPRM''' command from the usual '''SPPRM 4.0,,,,1.0,1''' to '''SPPRM 3.99,,,,1.0,1''', since the first number determines subfield size. | ||
A significant limitation of this approach is that the beam pitch as determined by the SHOT S command has a maximum value of 1020 units, i.e. 251 nm. The method described below does not have this limitation. | |||
{| style="border: none; border-spacing: 0; margin: 1em auto; text-align: center;" | |||
|- | |||
| [[Image:shot_placement.png|800px]] | |||
|- | |||
| colspan="1" style="text-align:center;| | |||
Example of shot placement. Left: The shot placement does not form an equidistant grid since the beam pitch does not fit an integer number of beam shots in the 4x4 µm subfield (indicated with dashed lines). Right: The beam pitch matches the subfield size and beam shots are placed in a perfect grid. | |||
|} | |||
==Array of small boxes approach== | |||
In this approach the pattern is an array of 2x2 nm boxes, each box will be filled with a single beam shot and hence the beam placement is determined by the boxes in the array. Thus, this is a more versatile approach as it allows the user to easily vary distance between shots and create hexagonal arrays or similar. The exposure is however somewhat slower since each shape adds a few ns of beam settling time. The beam pitch as setup in the SHOT S command should be large enough that a single beam shot is placed in each 2x2 nm box, i.e. it should just be larger than 2 nm. | |||
==Results== | ==Results== | ||
The results below are made with the approach described above. The pattern is defined in 180 nm AR-P 6200 on a silicon substrate, exposed at 29 nA. The circle size as a function of dwell time and beam pitch is illustrated in the graph. It is seen that the circle pitch has a significant impact on circle size even for the same dwell time, this is naturally due to the proximity effect and can not be avoided. The graph can however serve as a guide to chose the right combination of beam pitch and dwell time to obtain the array one desires. | |||
{| style="border: none; border-spacing: 0; margin: 1em auto; text-align: center;" | {| style="border: none; border-spacing: 0; margin: 1em auto; text-align: center;" | ||