Charged particle beam apparatus

• US 7,582,885 B2
• Filed: 04/12/2006
• Issued: 09/01/2009
• Est. Priority Date: 04/13/2005
• Status: Expired due to Fees

• Current Assignee: Hitachi High-Technologies Corporation (Hitachi, Ltd.)
• Original Assignee: Hitachi High-Technologies Corporation (Hitachi, Ltd.)
• Inventors: Ohshima, Takashi, Furukawa, Takashi, Sato, Mitsugu, Agemura, Toshihide, Katagiri, Souichi
• Primary Examiner(s): Vanore; David A
• Assistant Examiner(s): MASKELL, MICHAEL P
• Application Number:
  US11/401,878
• Publication Number:
  US 20060231773A1
• Time in Patent Office: 1,238 Days
• Field of Search: 250/492.3, 250/310, 250/311, 250/441.11, 250/396.ML, 417/48, 417/49, 313153-162
• US Class Current: 250/492.3
• CPC Class Codes: H01J 2237/0245 Moving whole optical system relatively to object
• CPC Class Codes: H01J 2237/062 Reducing size of gun
• CPC Class Codes: H01J 2237/06341 Field emission
• CPC Class Codes: H01J 2237/1825 Evacuating means
• CPC Class Codes: H01J 37/28 with scanning beams H01J37/268, H01J37/292, H01J37/2955 take precedence
• CPC Class Codes: H01J 41/12 Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps
• CPC Class Codes: H01J 41/14 with ionisation by means of thermionic cathodes

Abstract

A small-sized charged particle beam apparatus capable of maintaining high vacuum even during emission of an electron beam is provided. A nonevaporative getter pump is placed upstream of differential pumping of an electron optical system of the charged particle beam apparatus, and a minimum number of ion pumps are placed downstream, so that both the pumps are used in combination. Further, by mounting a detachable coil on an electron gun part, the inside of a column can be maintained under high vacuum with a degree of vacuum in the order of 10⁻⁸ Pa.

Claims

1. A magnetic-field-superposed electron gun comprising:

a differential pumping system comprising two or more vacuum chambers coupled together via an aperture;

a nonevaporative getter pump on an upstream side;

an ion pump in any of the vacuum chambers on a downstream;

an electron source on a most upstream vacuum chamber;

a permanent magnet in the proximity of the electron source,

wherein the permanent magnet is positioned as a center axis; and

at least two different magnetic poles at axisymmetric positions with respect to the electron source as the center axis.

2. The magnetic-field-superposed electron gun according to claim 1, further comprising;

a magnetic coil placed in the proximity of the electron source and being detachably attachable from an atmosphere side, instead of said permanent magnet.

3. A charged particle beam apparatus comprising:

a first vacuum chamber, having an electron source or ion source, on an upstream side;

a second vacuum chamber, coupled with the first vacuum chamber via an aperture, on a downstream side,

wherein the first vacuum chamber comprises a first nonevaporative getter pump and is absent from any ion pumps, and

wherein the second vacuum chamber comprises a second nonevaporative getter pump and ion pump; and

a column comprising the first and second vacuum chambers,

wherein the first nonevaporative getter pump is provided on the bore of the column and a heater to heat the first nonevaporative getter pump is provided outside the column.

4. A charged particle beam apparatus comprising:

first vacuum chamber, having an electron source or ion source, on an upstream side;

a second vacuum chamber, coupled with the first vacuum chamber via an aperture, on a downstream side,

wherein the first vacuum chamber comprises a first nonevaporative getter pump and is absent from any ion pump, and

wherein the second vacuum chamber comprises a second nonevaporative getter pump and ion pump;

a column comprising the first vacuum chamber and the second vacuum chamber; and

an electrode, provided with a first heater, arranged between the first vacuum chamber and the second vacuum chamber,

wherein the first nonevaporative getter pump is provided on the bore of the column and a second heater to heat the first nonevaporative getter pump is provided on the electrode.

5. The charged particle beam apparatus according to claim 4, further comprising:

a third nonevaporative getter pump provided on the bore of the column in the second vacuum chamber.