Patent Number: 
Section: claims

1. A charge particle beam apparatus comprising:a charged particle beam lens barrel configured to irradiate a charged particle beam;a gas nozzle configured to feed gas near a position on a sample at which the charged particle beam is irradiated; anda gas supply amount adjusting device configured to be periodically operated to control a flow rate of gas between a gas supply source and the gas nozzle to intermittently feed the gas to the gas nozzle side. 2. The charged particle beam apparatus according to claim 1, comprising a gas diffusion mechanism provided between the gas nozzle and the gas supply amount adjusting device,wherein a diameter of the gas diffusion mechanism is larger than diameters of a gas pipe arrangement connected to the gas supply amount adjusting device and the gas nozzle. 3. The charged particle beam apparatus according to claim 1, wherein a chemical change is caused on an irradiation surface by a reaction of gas with a charged particle beam, and a structural change is generated at that location. 4. The charged particle beam apparatus according to claim 1, wherein an electrical charge on a charged particle beam irradiation surface is neutralized by gas. 5. The charged particle beam apparatus according to claim 1, wherein the charged particle beam is an ion beam. 6. The charged particle beam apparatus according to claim 1, wherein the charged particle beam is an electron beam. 7. A charged particle beam apparatus comprising:a charged particle beam lens barrel that irradiates a charged particle beam onto a sample;a gas nozzle that feeds gas toward a region of the sample irradiated by the charge particle beam;a control device configured to control the flow rate of gas fed from a gas supply source by intermittently flowing the gas along a flow path to the gas nozzle; anda gas diffusion mechanism disposed in the flow path between the gas nozzle and the control device for diffusing and uniformizing the intermittent gas flow before it reaches the gas nozzle. 8. A charged particle beam apparatus according to claim 7; wherein the control device is configured to intermittently feed the gas in repeated cycles in which, in each cycle, the time during which gas is fed to the gas diffusion mechanism is less than the time during which gas is not fed from the diffusion mechanism. 9. A charged particle beam apparatus according to claim 7; including gas pipes connecting the gas nozzle to the gas diffusion mechanism and connecting the gas diffusion mechanism to the control device, the gas diffusion mechanism having a larger diameter than that of the gas pipes. 10. A charged particle beam apparatus according to claim 7; wherein the length of the gas diffusion mechanism is at least ten times longer than the distance through which the gas flows in one cycle. 11. A charged particle beam apparatus according to claim 7; wherein the charged particle beam is an ion beam. 12. A charged particle beam apparatus according to claim 7; wherein the charged particle beam is an electron beam. 13. A charged particle beam apparatus according to claim 1; wherein the gas supply amount adjusting device is periodically operated to obtain a gas flow rate on the order of 0.02 ml/min. 14. A charged particle beam apparatus according to claim 1; wherein the gas supply amount adjusting device has a minimum gas supply amount when operating continuously and is periodically operated to obtain a gas supply amount as small as one-tenth the minimum gas supply amount. 15. A charged particle beam apparatus according to claim 1; wherein the periodic operation of the gas supply amount adjusting device comprises ON/OFF cycles of operation in which the OFF period is multiple times longer than the ON period. 16. A charged particle beam apparatus according to claim 8; wherein in each cycle, the time during which gas is not fed is multiple times longer than the time during which gas is fed. 17. A charged particle beam apparatus according to claim 7; wherein the control device has a minimum flow rate when operating continuously and is configured to operate periodically to reduce the flow rate to a value below the minimum flow rate. 18. A charged particle beam apparatus according to claim 17; wherein the control device is configured to operate periodically to obtain a flow rate as low as 0.02 ml/min. 19. A charged particle beam apparatus comprising:a charged particle beam lens barrel that irradiates a charged particle beam onto a sample;a gas nozzle that feeds gas toward a region of the sample irradiated by the charged particle beam;control means for controlling the flow rate of gas fed from a gas supply source by intermittently flowing the gas along a flow path to the gas nozzle; anda gas diffusion mechanism disposed in the flow path between the gas nozzle and the control device for diffusing and uniformizing the intermittent gas flow before it reaches the gas nozzle. 20. A charged particle beam apparatus according to claim 19; wherein the control means is configured to intermittently feed the gas in repeated cycles in which, in each cycle, the time during which gas is fed to the gas diffusion mechanism is less than the time during which gas is not fed from the gas diffusion mechanism.