Specific Process Knowledge/Lithography/EBeamLithography/JBX9500Manual: Difference between revisions
No edit summary |
|||
| Line 37: | Line 37: | ||
[[File:colomn.png|400px]][[File:colomn2.png|400px]] | [[File:colomn.png|400px]][[File:colomn2.png|400px]] | ||
Pattern writing using the e-beam is implemented on a wafer or chip which has been coated with an electron | == Rough estimation of exposure time == | ||
<span style="font-size: 90%; text-align: right;">[[Specific_Process_Knowledge/Lithography/EBeamLithography/JBX9500Manual#top|Go to top of this page]]</span> | |||
[[File:currentbeamsize.jpg|400px|right]] | |||
Pattern writing using the e-beam writer is implemented on a wafer or chip which has been coated with an electron sensitive resist. Both positive and negative types of resists for pattern writing can be used. In either case, the resist sensitivity Q (C/cm2) is a function of the beam current, I (A), the pattern writing area, A (cm2), and the pattern writing time t (s), as given below: | |||
Q = It/A | Q = It/A | ||
The e-beam scanning | The e-beam scanning frequency f (Hz) is a function of the e-beam scanning step, p (shot step), as shown below: | ||
f = I /(Qp2) | f = I /(Qp2) | ||
The e-beam writer has scan speeds up to 100 MHz available. The dose, Q, shot step, p, and current, I, is chosen to meet the requirement of the pattern to be written, the writing time available, and also to meet the requirement f<100MHz. | The e-beam writer has scan speeds up to 100 MHz available. The dose, Q, shot step, p, and current, I, is chosen to meet the requirement of the pattern to be written, the writing time available, and also to meet the requirement f < 100MHz. | ||
Based on the equations above, a rough estimate of the exposure time is easily calcualted. In the second sheet of the e-beam logbook, a simple program for calculating the scan speed frequency and an estimation of the exposure time can be found. Note, that the actual writing time will exceed | Based on the equations above, a rough estimate of the exposure time is easily calcualted. In the second sheet of the e-beam logbook, a simple program for calculating the scan speed frequency and an estimation of the exposure time can be found. Note, that the actual writing time will exceed this estimated exposure-time, as the exposure-time calculation does not include pre-calibrations and stage movement during exposure. | ||