CHARGED PARTICLE BEAM APPARATUS

• US 20200135437A1
• Filed: 09/16/2019
• Published: 04/30/2020
• Est. Priority Date: 10/29/2018
• Status: Active Grant

• Current Assignee: Hitachi High-Tech Science Corporation (Hitachi, Ltd.)
• Original Assignee: Hitachi High-Tech Science Corporation (Hitachi, Ltd.)
• Inventors: OBA, Hiroshi, SUGIYAMA, Yasuhiko, OTSUKA, Yasutaka
• Granted Patent: US 11,017,988 B2
• Time in Patent Office: Days
• CPC Class Codes: H01J 2237/065 Source emittance characteristics
• CPC Class Codes: H01J 2237/24564 Measurements of electric or magnetic variables, e.g. voltage, current, frequency
• CPC Class Codes: H01J 2237/31749 Focused ion beam
• CPC Class Codes: H01J 37/08 Ion sources; Ion guns
• CPC Class Codes: H01J 37/304 Controlling tubes by information coming from the objects or from the beam, e.g. correction signals
• CPC Class Codes: H01J 37/32082 Radio frequency generated discharge H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence
• CPC Class Codes: H01J 37/321 the radio frequency energy being inductively coupled to the plasma
• CPC Class Codes: H01J 37/32357 Generation remote from the workpiece, e.g. down-stream
• CPC Class Codes: H01J 37/32422 Arrangement for selecting ions or species in the plasma
• CPC Class Codes: H01J 37/3244 Gas supply means
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge

Abstract

An charged particle beam apparatus includes: a gas introduction chamber to which raw gas is introduced; a plasma generation chamber connected to the gas introduction chamber; a coil wound around an outer circumference of the plasma generation chamber and receiving a high-frequency power; an extraction electrode applying an extraction voltage to plasma discharged from a plasma aperture at an outlet of the plasma generation chamber; an ampere meter measuring a magnitude of a plasma current caused by the plasma moved out of the plasma aperture; an extraction voltage calculator calculating, based on variation in the magnitude of the plasma current measured by the ampere meter with respect to variation in the extraction voltage, an extraction voltage set value; and a controller controlling the extraction voltage based on the extraction voltage set value calculated by the extraction voltage calculator.

Claims

1. A charged particle beam apparatus comprising:

a gas introduction chamber to which raw gas is introduced;

a plasma generation chamber connected to the gas introduction chamber;

a coil wound around an outer circumference of the plasma generation chamber and receiving high-frequency power;

an extraction electrode applying an extraction voltage to plasma discharged from a plasma aperture at an outlet of the plasma generation chamber;

an ampere meter measuring a magnitude of a plasma current caused by the plasma moved out of the plasma aperture;

an extraction voltage calculator calculating, based on variation in the magnitude of the plasma current measured by the ampere meter with respect to variation in the extraction voltage, an extraction voltage set value which is a set value of the extraction voltage; and

a controller controlling the extraction voltage based on the extraction voltage set value calculated by the extraction voltage calculator.

2. The charged particle beam apparatus of claim 1, wherein the ampere meter measures, among the plasma currents, an accelerating current caused by the plasma flowing from the plasma aperture toward an accelerating electrode, and

the extraction voltage calculator calculates, as the extraction voltage set value, the extraction voltage at a point of inflection at which the accelerating current reaches saturation with respect to the variation in the extraction voltage.

3. The charged particle beam apparatus of claim 1, wherein the ampere meter measures, among the plasma currents, a current introduced to extraction electrode caused by plasma flowing from the plasma aperture to the extraction electrode, and

the extraction voltage calculator calculates, as the extraction voltage set value, the extraction voltage at a point of inflection at which the current introduced to extraction electrode reaches saturation with respect to the variation in the extraction voltage.

4. The charged particle beam apparatus of claim 1, wherein the extraction voltage calculator calculates the extraction voltage set value from a point of inflection that is determined based on an increased amount of the plasma current with respect to the variation in the extraction voltage.

5. The charged particle beam apparatus of claim 2, wherein the extraction voltage calculator calculates the extraction voltage set value from a point of inflection that is determined based on an increased amount of the plasma current with respect to the variation in the extraction voltage.

6. The charged particle beam apparatus of claim 3, wherein the extraction voltage calculator calculates the extraction voltage set value from a point of inflection that is determined based on an increased amount of the plasma current with respect to the variation in the extraction voltage.

7. The charged particle beam apparatus of claim 1, wherein the extraction voltage set value is calculated for each plasma generation condition, and

the controller controls the extraction voltage, based on the extraction voltage set value that is associated with the plasma generation condition.

8. The charged particle beam apparatus of claim 2, wherein the extraction voltage set value is calculated for each plasma generation condition, and

the controller controls the extraction voltage, based on the extraction voltage set value that is associated with the plasma generation condition.

9. The charged particle beam apparatus of claim 3, wherein the extraction voltage set value is calculated for each plasma generation condition, and

the controller controls the extraction voltage, based on the extraction voltage set value that is associated with the plasma generation condition.

10. The charged particle beam apparatus of claim 4, wherein the extraction voltage set value is calculated for each plasma generation condition, and

the controller controls the extraction voltage, based on the extraction voltage set value that is associated with the plasma generation condition.

11. The charged particle beam apparatus of claim 5, wherein the extraction voltage set value is calculated for each plasma generation condition, and

the controller controls the extraction voltage, based on the extraction voltage set value that is associated with the plasma generation condition.

12. The charged particle beam apparatus of claim 6, wherein the extraction voltage set value is calculated for each plasma generation condition, and

the controller controls the extraction voltage, based on the extraction voltage set value that is associated with the plasma generation condition.