Electron beam apparatus and method of manufacturing semiconductor device using the apparatus
The present invention provides an electron beam apparatus for irradiating a sample with primary electron beams to detect secondary electron beams generated from a surface of the sample by the irradiation for evaluating the sample surface. In the electron beam apparatus, an electron gun has a cathode for emitting primary electron beams. The cathode includes a plurality of emitters for emitting primary electron beams, arranged apart from one another on a circle centered at an optical axis of a primary electro-optical system. The plurality of emitters are arranged such that when the plurality of emitters are projected onto a straight line parallel with a direction in which the primary electron beams are scanned, resulting points on the straight line are spaced at equal intervals.
1. An electron beam apparatus comprising:
an electron gun for emitting a plurality of primary electron beams;
a primary electro-optical system for irradiating a sample with the primary electron beams emitted from the electron gun;
a detector for detecting a plurality of secondary electron beams generated from the sample by the irradiation of the primary electron beams to evaluate the sample; and
a secondary electro-optical system for directing the secondary electron beams from the sample to the detector,
wherein the electron gun comprises a cylindrical cathode having, at its end facing the primary electro-optical system, and a plurality of emitter regions comprising a plurality of emitter chips for emitting the primary electron beams, respectively, and arranged such that when the center of each chip is projected onto a straight line in the X direction orthogonal to the center line of the bottom surface of said cathode, the projected emitter regions are spaced at substantially equal intervals.
2. An electron beam apparatus according to claim 1 , wherein the emitter regions are arranged apart from each other in a circle centered at an optical axis of the primary electro-optical system.
3. An electron beam apparatus according to claim 1 , further comprising:
an objective lens for accelerating the secondary electron beams generated from the sample;
a lens located between the objective lens and the electron gun; and
an ExB separator located between the objective lens and the lens located between the objective lens and the electron gun, for separating said secondary electron beams through the objective lens from the primary electro-optical system to direct them to the secondary electro-optical system,
wherein the detector comprises a plurality of detection devices for respectively detecting the secondary electron beams.
4. An electron beam apparatus according to claim 1 , wherein the emitter chips are arranged apart from each other to form a N×M matrix, where N and M are integers equal to or more than 2.
5. An electron beam apparatus according to claim 1 , wherein said cathode is made of a material included in a group consisting of LaB 6 , Ta, and Hf.