Wafer inspection apparatus

• US 10,641,714 B2
• Filed: 05/08/2018
• Issued: 05/05/2020
• Est. Priority Date: 06/15/2017
• Status: Active Grant

• Current Assignee: Korea Advanced Institute of Science and Technology, Korea Basic Science Institute
• Original Assignee: Korea Basic Science Institute
• Inventors: Park, Seung-young, Kim, Sang-il, Jo, Younghun, Min, Byoung-Chul
• Primary Examiner(s): Sanghera, Jas A
• Application Number:
  US15/974,111
• Publication Number:
  US 20180364181A1
• Time in Patent Office: 728 Days
• Field of Search: None
• CPC Class Codes: G01N 22/02 Investigating the presence of flaws

Abstract

Disclosed is a wafer inspection apparatus. The wafer inspection apparatus includes: a magnetic field generating unit forming a magnetic field such that magnetic lines of force flow in a direction perpendicular or parallel to a first surface of a wafer on which a magnetic thin film is formed; a microwave guide unit emitting microwaves to a measurement region that is at least a partial region of the wafer and is a region affected by the magnetic field generated by the magnetic field generating unit; and a sensing unit receiving waves reflected or transmitted after the microwaves are emitted to the measurement region from the microwave guide unit.

Claims

1. A wafer inspection apparatus, comprising:

a magnetic field generating unit forming a magnetic field such that magnetic lines of force flow in a direction perpendicular to a first surface of a wafer on which a magnetic film is formed and the magnetic lines of force also flow in a direction parallel to the first surface of the wafer;

a microwave guide unit emitting microwaves to a measurement region that is at least a partial region of the wafer and is a region affected by the magnetic field generated by the magnetic field generating unit, the microwave guide unit being arranged to be distanced from the first surface of the wafer by a predetermined distance when emitting microwaves; and

a sensing unit receiving waves reflected or transmitted after the microwaves are emitted to the measurement region from the microwave guide unit.

2. The wafer inspection apparatus of claim 1, wherein the sensing unit includes at least one of an antenna, a pick up coil, and a waveguide.

3. The wafer inspection apparatus of claim 1, further comprising:

a wafer stage supporting at least a part of the wafer,

wherein the wafer stage allows the wafer to be changed in position such that the measurement region on the wafer is changed in position.

4. The wafer inspection apparatus of claim 3, wherein a motion type in which the wafer is changed in position by the wafer stage includes at least one of a linear motion, a curved motion, and a vibration motion.

5. The wafer inspection apparatus of claim 1, further comprising:

a position adjustment unit changing a relative position of at least one of the magnetic field generating unit, the microwave guide unit, and the sensing unit with respect to an arbitrary point on the wafer, such that the measurement region on the wafer is changed in position.

6. The wafer inspection apparatus of claim 1, wherein the magnetic field generating unit includes:

a magnetic body inducing the magnetic lines of force in a direction toward the wafer; and

a coil wound so as to surround at least a part of the magnetic body such that electric power is supplied from outside and the magnetic lines of force are induced from the magnetic body to form the magnetic field.

7. The wafer inspection apparatus of claim 6, wherein the magnetic body has at least a part having one of E, I, J, L, and U shapes.

8. The wafer inspection apparatus of claim 6, further comprising:

an adiabatic material provided between the coil and the wafer to prevent heat generated in the coil from being transmitted to the wafer.

9. The wafer inspection apparatus of claim 6, wherein the magnetic body is one of a permanent magnet and an electromagnet, or is composed of a combination of the permanent magnet and the electromagnet.

10. The wafer inspection apparatus of claim 6, wherein the coil includes:

a DC coil forming a DC magnetic field by being supplied with DC power from the outside; and

an AC coil forming an AC magnetic field by being supplied with AC power from the outside.

11. The wafer inspection apparatus of claim 10, wherein intensity of the DC magnetic field formed by the DC coil is greater than intensity of the AC magnetic field formed by the AC coil.

12. The wafer inspection apparatus of claim 1, wherein the microwave guide unit includes:

a first rectangular waveguide emitting the microwaves to the measurement region where the magnetic lines of force are transmitted in the direction perpendicular to the first surface of the wafer by the magnetic field generating unit.

13. The wafer inspection apparatus of claim 1, wherein the microwave guide unit includes:

a second rectangular waveguide emitting the microwaves to the measurement region where the magnetic lines of force are formed in the direction parallel to the first surface of the wafer.

14. The wafer inspection apparatus of claim 1, wherein the microwave guide unit includes:

a coplanar waveguide emitting the microwaves to the measurement region.

15. The wafer inspection apparatus of claim 1, wherein the microwave guide unit includes:

a first rectangular waveguide emitting the microwaves to the measurement region where the magnetic lines of force are transmitted in the direction perpendicular to the first surface of the wafer by the magnetic field generating unit;

a second rectangular waveguide emitting the microwaves to the measurement region where the magnetic lines of force are formed in the direction parallel to the first surface of the wafer; and

a coplanar waveguide emitting the microwaves to the measurement region.

16. The wafer inspection apparatus of claim 15, wherein the first rectangular waveguide and the coplanar waveguide are arranged to be distanced from the first surface of the wafer by a predetermined distance, and

the second rectangular waveguide is arranged to be distanced from a second surface of the wafer by a predetermined distance, so that the microwaves are emitted to the measurement region.

17. The wafer inspection apparatus of claim 1, further comprising:

a signal processing unit receiving an electrical signal from the sensing unit and analyzing the received electrical signal,

wherein the sensing unit receives the waves reflected or transmitted and converts the received waves into the electrical signal, and

the signal processing unit analyzes information on the electrical signal received from the sensing unit, frequency of the microwaves emitted to the measurement region, and the magnetic field applied to the measurement region by the magnetic field generating unit and thus obtains magnetic information on the measurement region of the wafer.

18. The wafer inspection apparatus of claim 17, wherein the signal processing unit obtains, from the information on the electrical signal, the frequency, and the magnetic field, at least one of information including a change in effective saturation magnetization M_eff, a change in effective damping constant α

_eff, a thickness t of a ferromagnetic layer, and zero-frequency full width at half maximum Δ

H_C based on the following equation,