MAGNETIC DEVICE INSPECTION APPARATUS AND MAGNETIC DEVICE INSPECTION METHOD

• US 20100205699A1
• Filed: 12/30/2009
• Published: 08/12/2010
• Est. Priority Date: 01/05/2009
• Status: Active Grant

• Current Assignee: Hitachi High-Technologies Corporation (Hitachi, Ltd.)
• Original Assignee: Hitachi High-Technologies Corporation (Hitachi, Ltd.)
• Inventors: Tokutomi, Teruaki, TACHIZAKI, Takehiro, Nakagomi, Tsuneo, Sasazawa, Hideaki, Watanabe, Masahiro, Yoshida, Minoru
• Granted Patent: US 8,359,661 B2
• Time in Patent Office: Days
• US Class Current: 850/47
• CPC Class Codes: B82Y 15/00 Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: B82Y 35/00 Methods or apparatus for measurement or analysis of nanostructures
• CPC Class Codes: G01Q 60/54 Probes, their manufacture, or their related instrumentation, e.g. holders
• CPC Class Codes: G01Q 60/56 Probes with magnetic coating
• CPC Class Codes: G01Q 70/12 Nanotube tips

Abstract

Applying an alternating current to a magnetic head as a sample generates an alternate-current magnetic field from the sample. A cantilever includes a probe that is made of a magnetic material or is coated with a magnetic material. The cantilever is displaced when it approaches the sample. Detecting the displacement of the cantilever detects distribution of the magnetic field from the sample. It is possible to fast measure distribution of the magnetic field generated from the sample when a frequency of the alternating current applied to the sample differs from a resonance frequency of the cantilever.

Claims

1. A magnetic device inspection apparatus for detecting a magnetic field generated from a sample, the apparatus comprising:

a cantilever having a magnetic material probe or a probe coated with a magnetic material;

a sample base for holding the sample;

displacement detection means for observing displacement at a tip of the cantilever;

means capable of allowing the probe to repeatedly approach, retract, and travel in relation to the sample; and

means for detecting displacement at the tip of the cantilever,

wherein the magnetic device inspection apparatus excites the sample using an alternating current at a frequency different from a resonance frequency of the cantilever and measures distribution of a magnetic field generated from the sample.

2. The magnetic device inspection apparatus according to claim 1,

wherein a frequency of the alternating current for exciting the sample is equivalent to N or 1/N multiplied by resonance frequency f of the cantilever having the probe, where N is an integer equal to or greater than 2.

3. The magnetic device inspection apparatus according to claim 1,

wherein an alternating current without offset excites the sample and a frequency of the alternating current is equivalent to N/2 or 1/2N multiplied by resonance frequency f of the cantilever having the probe.

4. The magnetic device inspection apparatus according to claim 1,

wherein an alternating current with offset excites the sample and a frequency of the alternating current is equivalent to N or 1/N multiplied by resonance frequency f of the cantilever having the probe.

5. The magnetic device inspection apparatus according to claim 1,

wherein a carrier frequency for the alternating current is higher than a frequency for exciting the cantilever and an envelope frequency of the alternating current is equivalent to a vibration frequency capable of exciting the cantilever.

6. The magnetic device inspection apparatus according to claim 1,

wherein a frequency of the alternating current is higher than a frequency for exciting the cantilever and an amplitude of the alternating current is cyclically amplitude-modulated at a frequency capable of displacing the cantilever.

7. The magnetic device inspection apparatus according to claim 1,

wherein the cantilever is fixed to a vibration element and an oscillator vibrates the vibration element.

8. The magnetic device inspection apparatus according to claim 1,

wherein the cantilever is vibrated by any one of:

an elastic wave from outside a holding section for holding the cantilever;

applying an alternating current to a capacitor including the cantilever and an electrode; and

applying an alternate-current magnetic field to a magnetic material provided for part of the cantilever.

9. The magnetic device inspection apparatus according to claim 1, comprising:

means for sweeping a frequency of the alternating current; and

means for detecting a vibration frequency equivalent to a frequency of the alternating current.

10. The magnetic device inspection apparatus according to claim 1, comprising:

means for generating a known magnetic field and maintaining a specified state for a magnetization condition of the probe at least part of which is coated with a magnetic material film or is made of a magnetic material.

11. The magnetic device inspection apparatus according to claim 1, comprising:

means for including a standard coil for generating a given magnetic field or a magnetic material for calibration and calibrates a magnetic field intensity measured by the probe at least part of which is coated with a magnetic material film or is made of a magnetic material.

12. The magnetic device inspection apparatus according to claim 1,

wherein a signal detects displacement at the tip of the cantilever vibrated by a magnetic field generated from the sample;

and

wherein the apparatus lock-in-detects the signal at a frequency of the alternating current for exciting the sample and selectively detects only a response component relevant to excitation of the sample.

13. The magnetic device inspection apparatus according to claim 1,

wherein, when observing a sample having fine irregularity on a surface of the sample, the apparatus previously corrects a slant of the sample surface using a quantity measured by an optical lever or contact with the probe and allows the probe to two-dimensionally scan along the corrected slant by maintaining a specified distance from a surface of the sample.

14. The magnetic device inspection apparatus according to claim 1,

wherein optical interferometry or a scanning probe microscope is used to previously measure a surface slant and irregularity of the sample;

and

wherein the probe follows irregularity of the sample surface for scanning while maintaining a constant distance from the sample surface.

15. The magnetic device inspection apparatus according to claim 1,

wherein a bright-field optical microscope or a dark-field optical microscope is used to previously detect a position and a size of a foreign particle on a sample surface;

and

wherein the probe two-dimensionally scans the sample surface with or without keeping a specified distance therefrom while avoiding the foreign particle.

16. The magnetic device inspection apparatus according to claim 1,

wherein the apparatus previously detects a position of the sample through contact with the sample outside a region including a measurement object, allows a probe to scan by keeping a distance specified after contact away from the sample, and performs contactless observation in the region including the measurement object of the sample.

17. The magnetic device inspection apparatus according to claim 1,

wherein the apparatus brings a probe into contact with the sample so as to apply a current for exciting the sample, thereby using a microscope or a telescope capable of observing a tip of the probe and an electrode surface of the sample from a rear or a side of the probe.

18. A magnetic device inspection method of detecting distribution of a magnetic field generated from a magnetic device, comprising the steps of:

setting up the magnetic device;

selecting an item for inspecting the magnetic device;

configuring a parameter for inspecting the magnetic device;

allowing a cantilever having a probe and a position detector for sensing movement of the cantilever to approach the magnetic device;

applying an exciting current to the magnetic device;

determining a measurement position on the magnetic device;

performing measurement in accordance with the selected inspection item and the configured parameter;

analyzing magnetic field distribution data for the magnetic device resulting from the measurement and evaluating the selected item; and

displaying a result of the evaluation,

wherein a frequency of the alternating current for exciting the magnetic device differs from a resonance frequency of the cantilever having the probe;

wherein the position detector measures displacement of the cantilever; and

wherein a frequency filter uses a measurement result for signal processing.

19. The magnetic device inspection method according to claim 18,

wherein a frequency of the alternating current is selected so that a frequency band allows a vibration amplitude of the cantilever to be larger than a noise level and that a time constant for vibration of the cantilever is smaller than a time constant for a resonance frequency of the cantilever.

20. The magnetic device inspection method according to claim 18,

wherein the frequency filter is equivalent to a band rejection filter so that a cutoff frequency toward low frequency is lower than a resonance frequency of the cantilever and a cutoff frequency toward high frequency is higher than a resonance frequency of the cantilever.