Particle detection system
This invention provides a design to process a large range of detection beam current at low noise with a single detector. With such a design, the detection system can generate up to 10 10 gain and maximum signal output at more than mini Ampere (mA) level. A condenser lens is configured to increase bandwidth of the detector that scan speed can be enhanced.
1. An E-beam wafer inspection tool, comprising:
an electron gun for emitting a primary beam;
a primary beam condenser lens for condensing the primary beam;
an objective lens for receiving the primary beam from said primary beam condenser lens and focusing the primary beam on to a surface of a specimen; and
a particle detection system, comprising:
a charged particle multiplier device for receiving original signal particles to be detected and generating a plurality of multiplied charged particles, and the detected signal particles include a secondary charged particles emitted from the surface of the specimen;
a charged particle detection device for receiving the plurality of multiplied charged particles and generating output signal corresponding to the original signal particles; and
a condenser lens is configured between said charged particle multiplier device and said charged particle detection device to converge the plurality of multiplied charged particles into said charged particle detection device.
2. The E-beam wafer inspection tool according to claim 1 , wherein an electric potential is applied between the charged particle multiplier device and the charged particle detection device to accelerate the plurality of multiplied charged particles to arrive the charged particle detection device to obtain the second level gain.
3. The E-beam wafer inspection tool according to claim 1 , wherein said charged particle detection device is a semiconductor photo diode.
4. The E-beam wafer inspection tool according to claim 3 , wherein said original signal particles are original charged signal particles.
5. The E-beam wafer inspection tool according to claim 4 , wherein said charged particle multiplier device is a microchannel plate.
6. The E-beam wafer inspection tool according to claim 4 , wherein said original signal particles are electrons.
7. The E-beam wafer inspection tool according to claim 6 , wherein said charged particle multiplier device is an electron multiplier.
8. The E-beam wafer inspection tool according to claim 7 , wherein an electric field is applied between the charged particle multiplier device and the charged particle detection device to accelerate the plurality of multiplied charged particles.
9. The E-beam wafer inspection tool according to claim 7 , wherein the condenser lens is an electrostatic lens configured between said charged particle multiplier device and said charged particle detection device.
10. The E-beam wafer inspection tool according to claim 9 , wherein gain of the particle detection system can be adjusted by an electric field from the electrostatic lens.
11. The E-beam wafer inspection tool according to claim 10 , wherein a potential difference of the electric field applied between the charged particle multiplier device and the charged particle detection device can be ranged from 5 KV to 15 KV.
12. The E-beam wafer inspection tool according to claim 11 , further comprising a metal mesh configured to said charged particle multiplier device.
13. The E-beam wafer inspection tool according to claim 12 , further comprising an energy filter between the charge particle multiplier device and the metal mesh.
14. The E-beam wafer inspection tool according to claim 13 , further comprising a means for driving the original particles from the metal mesh to the energy filter.
15. The E-beam wafer inspection tool according to claim 14 , wherein the means for driving the original particles is draft tube structure.