Specific Process Knowledge/Lithography/EBeamLithography/EBLProcessExamples: Difference between revisions
| Line 37: | Line 37: | ||
==Single big box approach== | ==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. | 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. | |||
{| style="border: none; border-spacing: 0; margin: 1em auto; text-align: center;" | {| style="border: none; border-spacing: 0; margin: 1em auto; text-align: center;" | ||