Charged particle beam apparatus
View Patent ↗A charged particle beam apparatus is provided which has high resolving power and a wide scanning region (observation field of view). The apparatus has a unit for adjusting the focus, a unit for adjusting astigmatism, a unit for controlling and detecting scanning positions and a controller operative to control the focus adjustment and astigmatism adjustment at a time in interlocked relation to the scanning positions, thereby assuring compatibility between the high resolving power and the observation view field of a wide area.
1. A scanning electron microscope for obtaining an image of a scanned region of a specimen by a primary electron beam, comprising:
an electron optical system including an electron gun for emitting the primary electron beam, an objective lens for converging the primary electron beam and generating a focal point on the specimen, and a deflector for scanning the primary electron beam on a scanning region of the specimen;
a focus adjustment means for adjusting a focal position of the primary electron beam by controlling said objective lens;
a stigmator for adjusting an astigmatic aberration of the primary electron beam;
a memory means for storing a relation between either an astigmatism adjusting value used by said stigmator or a focus adjustment value used by said focus adjustment means, and either a deflection position or a deflection angle of the primary electron beam by said deflector;
a controller for controlling said stigmator, said deflector and said focus adjustment means,
wherein said controller controls said focus adjustment means so that the primary electron beam is focused on the specimen in accordance with said relation and in interlocked relation to the scanning position of the primary electron beam, or controls said stigmator so that the astigmatic aberration of the primary electron beam is corrected in accordance with said relation and in interlocked relation to the scanning position of the primary electron beam; and
a focus correction electrode for adjusting the focal position of the primary electron beam;
wherein said scanning region is divided into a plurality of areas, and adjustment values for adjusting said focal position to each of the areas or adjustment values for correcting said astigmatic aberration beam to each of the areas are stored in said memory means in correspondence with positions of said divided areas in the scanning region, and
wherein the adjustment value to a divided area including a center of the scanning region is determined by using the focus adjustment means, while the adjustment values to the other divided areas of the scanning region are determined by using the focus correction electrode.
2. The scanning electron microscope according to claim 1 , wherein said deflector is an electromagnetic type deflector, and
said controller controls a value of a current for supplying to said electromagnetic type deflector.
3. The scanning electron microscope according to claim 1 , wherein said deflector is an electrostatic type deflector, and
said controller controls a value of a voltage applied to said electrostatic type deflector.
4. The scanning electron microscope according to claim 1 ,
wherein said adjustment values are stored as a functional expression of the deflection position or the deflection angle of said primary electron beam.
5. The scanning electron microscope according to claim 1 , further comprising: display means for displaying said image by using an output of a detector.
6. The scanning electron microscope according to claim 1 ,
wherein said stigmator is an electrostatic type stigmator.
7. The scanning electron microscope according to claim 1 ,
wherein said stigmator controls a stigmator coil.
8. An inspection apparatus utilizing a scanning electron microscope for obtaining an image of predetermined scanning region, said scanning electron microscope further comprising:
an electron optical system including an electron gun for emitting the primary electron beam, an objective lens for converging the primary electron beam and generating a focal point on the specimen, and a deflector for scanning the primary electron beam on a scanning region of the specimen;
a focus adjustment means for adjusting a focal position of the primary electron beam by controlling said objective lens;
a stigmator for adjusting an astigmatic aberration of the primary electron beam;
a memory means for storing a relation between either an astigmatism adjusting value used by said stigmator or a focus adjustment value used by said focus adjustment means, and either a deflection position or a deflection angle of the electron beam by said deflector; and
a controller for controlling said stigmator, said deflector and said focus adjustment means,
wherein said controller controls said focus adjustment means so that the primary electron beam is focused on the specimen in accordance with said relation and in interlocked relation to the scanning position of the primary electron beam or controls said stigmator so that the astigmatic aberration of the primary electron beam is corrected in accordance with said relation and in interlocked relation to the scanning position of the primary electron beam; and
a focus correction electrode for adjusting the focal position of the primary electron beam;
wherein said scanning region is divided into a plurality of areas, and adjustment values for adjusting said focal position to each of the areas or adjustment values for correcting said astigmatic aberration beam to each of the areas are stored in said memory means in correspondence with positions of said divided areas in the scanning region, and
wherein the adjustment value to a divided area including a center of the scanning region is determined by using the focus adjustment means, while the adjustment values to the other divided areas of the scanning region are determined by using the focus correction electrode.