1. A human body back-scattering inspection system, comprising:
a first back-scattering scanning device and a second back-scattering scanning device which are placed in opposite positions relative to each other so that an object to be inspected stands therebetween when it is to be scanned, the first back-scattering scanning device comprising a first X-ray source, a first flying-spot forming unit, and a first detector, the first flying-spot forming unit having a plurality of holes that are distributed spirally on its cylindrical surface and outputting beams of X-rays, the first detector receiving beams of X-rays that are reflected from body of the inspected object, the second back-scattering scanning device comprising a second X-ray source, a second flying-spot forming unit, and a second detector, the second flying-spot forming unit having a plurality of holes that are distributed spirally on its cylindrical surface and outputting beams of X-rays, the second detector receiving beams of X-rays that are reflected from body of the inspected object; and
a controlling unit coupled to the first and second back-scattering scanning devices, and configured to generate controlling signals to cause the first flying-spot forming unit and the second flying-spot forming unit to output the beams of X-rays at time which is different by about a half of a cycle of the intensity of beams varying over time;
wherein diameter of holes and space between holes on the cylindrical surface of the flying-spot forming units are adjusted to reduce intensity of beams emitted from the second back-scattering scanning device when the first detector collects signals, and reduce intensity of beams emitted from the first back-scattering scanning device when the second detector collects signals.
2. The human body back-scattering inspection system according to claim 1, wherein the controlling unit is configured to generate controlling signals to cause the first and second back-scattering scanning devices to start at time that is different by about a half of a cycle of the intensity of beams varying over time.
3. The human body back-scattering inspection system according to claim 1, wherein the controlling unit is configured to generate controlling signals to cause the first detector to collect only reflected beams of X-rays about peaks of the beams of X-rays emitted from the first flying-spot forming unit, and to cause the second detector to collect only reflected beams of X-rays about peaks of the beams of X-rays emitted from the second flying-spot forming unit.
4. A human body back-scattering inspection system, comprising:
a first back-scattering scanning device and a second back-scattering scanning device which are placed in opposite positions relative to each other so that an object to be inspected stands therebetween when it is to be scanned, the first back-scattering scanning device comprising a first X-ray source, a first flying-spot forming unit and a first detector, the first flying-spot forming unit outputting beams of X-rays, the first detector receiving beams of X-rays that are reflected from body of the inspected object, the second back-scattering scanning device comprising a second X-ray source, a second flying-spot forming unit and a second detector, the second flying-spot forming unit outputting beams of X-rays, the second detector receiving beams of X-rays that are reflected from body of the inspected object; and
a controlling unit coupled to the first and second back-scattering scanning devices, and configured to generate controlling signals to cause the first and second detectors to collect reflected beams of X-rays in a time-sharing manner;
wherein each of the first flying-spot forming unit and the second flying-spot forming unit has a plurality of holes that are distributed spirally on its cylindrical surface and outputs beams of X-rays therefrom;
wherein diameter of holes and space between holes on the cylindrical surface of the flying-spot forming units are adjusted to reduce intensity of beams emitted from the second back-scattering scanning device when the first detector collects signals, and reduce intensity of beams emitted from the first back-scattering scanning device when the second detector collects signals.
5. A method for use in a human body back-scattering inspection system comprising a first back-scattering scanning device and a second back-scattering scanning device which are placed in opposite positions relative to each other so that an object to be inspected stands therebetween when it is to be scanned, the first back-scattering scanning device comprising a first X-ray source, a first flying-spot forming unit, and a first detector, the first flying-spot forming unit having a plurality of holes that are distributed spirally on its cylindrical surface and outputting beams of X-rays, the first detector receiving beams of X-rays that are reflected from body of the inspected object, the second back-scattering scanning device comprising a second X-ray source, a second flying-spot forming unit, and a second detector, the second flying-spot forming unit having a plurality of holes that are distributed spirally on its cylindrical surface and outputting beams of X-rays, the second detector receiving beams of X-rays that are reflected from body of the inspected object, the method comprising:
generating controlling signals to cause the first flying-spot forming unit and the second flying-spot forming unit to output the beams of X-rays at time which is different by a half of a cycle of the intensity of beams varying over time;
wherein diameter of holes and space between holes on the cylindrical surface of the flying-spot forming units are adjusted to reduce intensity of beams emitted from the second back-scattering scanning device when the first detector collects signals, and reduce intensity of beams emitted from the first back-scattering scanning device when the second detector collects signals.
6. The method according to claim 5, further comprising
generating controlling signals to cause the first and second back-scattering scanning devices to start at time that is different by about a half of the cycle of the intensity of beams varying over time.
7. The method according to claim 5, further comprising
generating controlling signals to cause the first detector to collect only reflected beams of X-rays about peaks of the beams of X-rays emitted from the first flying-spot forming unit, and to cause the second detector to collect only reflected beams of X-rays about peaks of the beams of X-rays emitted from the second flying-spot forming unit.
8. A method for use in a human body back-scattering inspection system comprising a first back-scattering scanning device and a second back-scattering scanning device which are placed in opposite positions relative to each other so that an object to be inspected stands therebetween when it is to be scanned, the first back-scattering scanning device comprising a first X-ray source, a first flying-spot forming unit, and a first detector, the first flying-spot forming unit outputting beams of X-rays, the first detector receiving beams of X-rays that are reflected from body of the inspected object, the second back-scattering scanning device comprising a second X-ray source, a second flying-spot forming unit, and a second detector, the second flying-spot forming unit outputting beams of X-rays, the second detector receiving beams of X-rays that are reflected from body of the inspected object, wherein each of the first flying-spot forming unit and the second flying-spot forming unit has a plurality of holes that are distributed spirally on its cylindrical surface and outputs beams of X-rays therefrom, the method comprising
generating controlling signals to cause the first and second detectors to collect reflected beams of X-rays in a time-sharing manner;
wherein diameter of holes and space between holes on the cylindrical surface of the flying-spot forming units are adjusted to reduce intensity of beams emitted from the second back-scattering scanning device when the first detector collects signals, and reduce intensity of beams emitted from the first back-scattering scanning device when the second detector collects signals.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for fabricating a flash memory device, comprising:
providing a substrate having thereon a dielectric layer and a first silicon layer;
forming a cavity in the first silicon layer and the dielectric layer to expose a portion of the substrate;
forming a control gate oxide layer on the exposed substrate within the cavity;
forming an insulating layer on interior surface of the cavity and on the first silicon layer;
forming a second silicon layer on the insulating layer, wherein the second silicon layer fills the cavity;
forming a photoresist pattern on the second silicon layer;
performing an etching process to etch the second silicon layer, the insulating layer and the first silicon layer not covered by the photoresist pattern, thereby forming a T-shaped control gate and a floating gate;
performing a tilt-angle ion implantation process to form an N+ pocket doping region under the floating gate;
forming a spacer on a sidewall of the floating gate; and
performing a heavy ion implantation process to form a P+ sourcedrain region in the substrate next to the spacer.
2. The method according to claim 1, wherein the dielectric layer comprises a silicon oxide layer.
3. The method according to claim 2, wherein the first silicon layer comprises polysilicon.
4. The method according to claim 3, wherein the second silicon layer comprises polysilicon.
5. The method according to claim 4, wherein the spacer comprises silicon nitride.
6. The method according to claim 5, wherein dopants used in the tilt-angle ion implantation process comprises arsenic.
7. The method according to claim 6, wherein the insulating layer comprises oxide-nitride-oxide (ONO) dielectric layer.
8. A flash memory cell, comprising:
a substrate;
a control gate oxide layer on the substrate;
a T-shaped control gate on the control gate oxide layer;
a floating gate disposed on two recessed sidewalls of the T-shaped control gate;
an insulating layer between the control gate and the floating gate;
a dielectric layer between the floating gate and the substrate;
a spacer on a sidewall of the floating gate;
a P+ sourcedrain region in the substrate next to the spacer; and
an N+ pocket region encompassing the P+ sourcedrain region and covering an area directly under the floating gate.
9. The flash memory cell according to claim 8, wherein the substrate comprises P type substrate.
10. The flash memory cell according to claim 9, wherein the dielectric layer comprises silicon oxide layer.
11. The flash memory cell according to claim 10, wherein the spacer comprises silicon nitride.
12. The flash memory cell according to claim 11, wherein the insulating layer comprises oxide-nitride-oxide (ONO) dielectric layer.