Ultra high precision measurement tool with control loop
View Patent ↗A focused ion beam device is described comprising a gas field ion source with an emitter emitting an ion beam including ions of gas, an ion beam column and a beam current control loop comprising a beam current measurement device. Furthermore, the focused ion beam device may have a sample charge control comprising measuring the sample charge. A method of operating a focused ion beam device is provided comprising applying a voltage between an emitter an electrode, applying gas to the emitter, emitting ions of a gas from the emitter and controlling a beam current by measuring the beam current with a beam current measurement device.
1. A focused ion beam device, comprising
a gas field ion source having an emitter adapted to emit an ion beam including ions of gas;
an ion beam column;
a beam current control loop configured for automatically triggering a probe current control action comprising a beam current measurement device configured for measuring the beam current emitted from the emitter in the column or the current provided to the emitter; and
a sample charge feedback control comprising a charge measurement unit.
2. The focused ion beam device according to claim 1 , wherein the emitter comprises an emitter base tip and an emitter supertip.
3. The focused ion beam device according to claim 2 , wherein the supertip has one single atom at its apex.
4. The focused ion beam device according to claim 1 , further comprising an analyzer for analyzing the structure of a specimen.
5. The focused ion beam device according claim 1 , wherein the beam current measurement device comprises a Faraday cup.
6. The focused ion beam device according to claim 1 , wherein the beam current measurement device comprises a beam limiting aperture.
7. The focused ion beam device according to claim 1 , further comprising a deflector directing the ion beam to the measurement device.
8. The focused ion beam device according to claim 7 , wherein the deflector is a beam blanker.
9. The focused ion beam device according to claim 1 , wherein the sample charge control comprises a spectrometer.
10. The focused ion beam device according to claim 1 , wherein the sample charge control comprises a retarding field configuration.
11. The focused ion beam device according to claim 1 , wherein the sample charge measurement unit comprises a detector.
12. The focused ion beam device according to claim 1 , wherein the sample charge control comprises a sample charge measurement unit and a detector.
13. A method of operating an ion beam device, having an ion beam column; a gas field ion source with an emitter in a emitter region, the method comprising:
applying a voltage between the emitter and an electrode with a voltage source;
applying a gas to the emitter region by a gas feeding unit;
emitting ions of a gas from the emitter;
automatically controlling a beam current by measuring the beam current emitted from the emitter in the column or the current provided to the emitter with a beam current measurement device and by feeding the information to a control connected to at least one of the voltage source, the condenser voltage and the gas feeding unit, wherein the measurement of the beam current is used as a signal for changing the beam current;
measuring and controlling the sample charge; and
triggering compensation measures based on the measurement of the sample charge,
wherein a stability of the beam current of is provided a range of 10% or less.
14. The method according to claim 13 , wherein the gas is helium, hydrogen, neon, argon or methane.
15. The method according to claim 13 , wherein the emitter has a single emission centre.
16. The method according to claim 13 , further comprising controlling the beam current changes when the changes have reached a predetermined limit.
17. The method according to claim 13 , further comprising deflecting an ion beam for measuring the beam current.
18. The method according to claim 13 , wherein the sample charge is measured and controlled during operation of the ion beam device.
19. The method according to claim 13 , further comprising supplying a control voltage to the sample after measuring the sample charge.