KR101875058B1 - Apparatus for detecting characteristics and defect of thin-film - Google Patents

Apparatus for detecting characteristics and defect of thin-film Download PDF

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Publication number
KR101875058B1
KR101875058B1 KR1020160176372A KR20160176372A KR101875058B1 KR 101875058 B1 KR101875058 B1 KR 101875058B1 KR 1020160176372 A KR1020160176372 A KR 1020160176372A KR 20160176372 A KR20160176372 A KR 20160176372A KR 101875058 B1 KR101875058 B1 KR 101875058B1
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South Korea
Prior art keywords
thin film
beam
probe beam
pump beam
pump
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KR1020160176372A
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Korean (ko)
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KR20180073001A (en
Inventor
박익근
박해성
강동찬
김주한
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서울과학기술대학교 산학협력단
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Priority to KR1020160176372A priority Critical patent/KR101875058B1/en
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using infra-red, visible or ultra-violet light
    • G01N21/84Systems specially adapted for particular applications
    • G01N21/88Investigating the presence of flaws or contamination
    • G01N21/8851Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using infra-red, visible or ultra-violet light
    • G01N21/84Systems specially adapted for particular applications
    • G01N21/88Investigating the presence of flaws or contamination
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B26/00Optical devices or arrangements using movable or deformable optical elements for controlling the intensity, colour, phase, polarisation or direction of light, e.g. switching, gating, modulating
    • G02B26/08Optical devices or arrangements using movable or deformable optical elements for controlling the intensity, colour, phase, polarisation or direction of light, e.g. switching, gating, modulating for controlling the direction of light
    • G02B26/10Scanning systems
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B26/00Optical devices or arrangements using movable or deformable optical elements for controlling the intensity, colour, phase, polarisation or direction of light, e.g. switching, gating, modulating
    • G02B26/08Optical devices or arrangements using movable or deformable optical elements for controlling the intensity, colour, phase, polarisation or direction of light, e.g. switching, gating, modulating for controlling the direction of light
    • G02B26/10Scanning systems
    • G02B26/105Scanning systems with one or more pivoting mirrors or galvano-mirrors
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B27/00Other optical systems; Other optical apparatus
    • G02B27/10Beam splitting or combining systems
    • G02B27/14Beam splitting or combining systems operating by reflection only
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B27/00Other optical systems; Other optical apparatus
    • G02B27/10Beam splitting or combining systems
    • G02B27/14Beam splitting or combining systems operating by reflection only
    • G02B27/149Beam splitting or combining systems operating by reflection only using crossed beamsplitting surfaces, e.g. cross-dichroic cubes or X-cubes

Abstract

The thin film inspection system for measuring the characteristics and defects of a thin film is composed of a pulse laser for irradiating a pump beam to generate a surface wave on the thin film, an interferometer from a light beam irradiated from the continuous oscillation laser, A pump beam and a probe beam, a reflection mirror coaxially reflecting the pump beam and the probe beam, and a coaxially reflected pump beam and a probe beam are received, and a thin film A scan unit for scanning the thin film by irradiating the pump beam and the probe beam, and a signal processor for measuring the characteristics and defects of the thin film.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a thin film inspection apparatus for measuring characteristics and defects of a thin film,

The present invention relates to a thin film inspection apparatus for measuring characteristics and defects of a thin film.

Conventional thin film inspection devices used for measuring physical properties (hardness, bonding strength, surface roughness, etc.) of a thin film include nanoindentation, scratch test, AFM (Atomic Force Microscope) As a formula, the displacement generated by applying a load to the test piece is numerically expressed. However, there is a problem that the intrinsic properties of the thin film change when the thin film inspection apparatus physically contacts the test piece.

On the other hand, there are SEM (Scanning Electron Microscope) and Ellipsometer, which are thin film inspection devices for measuring the thickness of a thin film, and these devices have a problem that pretreatment of the test piece must be performed indispensably. In particular, SEM must be able to measure the thickness of a specimen by separating the specimen and observing the cross-section.

Recently, a method of measuring the characteristics and defects of a thin film without contacting the thin film using a pulse laser and an interferometer has been proposed.

1 is a view showing a conventional thin film inspection apparatus using a pulsed laser and an interferometer (Patent No. 10-0924199). Referring to FIG. 1, a conventional thin film inspection apparatus is provided with a laser irradiation system 100 and a laser interferometer 110 in a transfer unit 120. A laser interferometer 110 provided on the transfer unit 120 is used to irradiate a thin film 10 with a pulsed laser beam by using a laser irradiation system 100 provided in the transfer unit 120 and to transfer a surface wave generated by the pulsed laser beam, Is irradiated with a laser beam for measurement. The thin film inspection apparatus detects the defect of the thin film while moving the transfer unit 120.

On the other hand, the surface wave velocity is greatly influenced by the density and the elastic modulus of the medium (material), and thus the surface wave attenuation rate tends to vary greatly depending on the material of the thin film. For example, stainless steel has a faster decay rate, and aluminum and iron have a slower decay rate.

Therefore, in order to accurately measure the characteristics and defects of a thin film by using a pulse laser and an interferometer, it is necessary to vary the distance between the point where the surface wave is generated by the pulse laser and the receiving part for each material of the thin film.

However, in the conventional thin film inspection apparatus shown in FIG. 1, since the laser irradiation system 100 and the laser interferometer 110 are installed in the transfer unit 120 at a predetermined distance from each other, It is difficult to control the distance between them.

In particular, due to the physical size of the laser irradiation system 100 and the laser interferometer 110, it is impossible to reduce the distance between the surface wave generation point and the reception unit to a certain distance or less.

In order to solve the above-described problems of the conventional thin film inspection apparatus, the present invention is directed to a method of measuring a thin film characteristic and a defect while scanning a thin film by coaxially entering a pump beam irradiated from a pulse laser and a probe beam irradiated from an interferometer do. Also, it is desirable to control the separation distance between the pump beam and the probe beam according to the position at which the pump beam and the probe beam are incident. It is to be understood, however, that the technical scope of the present invention is not limited to the above-described technical problems, and other technical problems may exist.

According to a first aspect of the present invention, there is provided a thin film inspection apparatus for measuring characteristics and defects of a thin film, comprising: a pulse laser for irradiating a pump beam for generating a surface wave to a thin film; An interferometer unit for generating an interferometer from a light beam irradiated from a continuous oscillation laser and irradiating a probe beam for measuring a surface wave generated in the thin film, an interferometer for receiving the pump beam and the probe beam, A scan unit for receiving the pump beam and the probe beam reflected by the coaxial reflecting mirror, coaxially reflecting the probe beam, and scanning the thin film by irradiating the pump beam and the probe beam onto the thin film, And a signal processing unit for measuring the characteristics and defects of the signal.

In one embodiment, the reflecting mirror is a dichroic mirror, and the dichroic mirror can pass the probe beam and reflect the pump beam.

For example, the reflection mirror may be configured to control a separation distance between the pump beam and the probe beam according to a position at which the pump beam and the probe beam are incident.

In one embodiment, the scanning unit is a galvanometer, and the galvanometer can irradiate the pump beam and the probe beam having the separation distance to the thin film.

In one embodiment, the spacing distance may be less than a distance at which the pump beam and the probe beam can be directly irradiated to the thin film by the pulse laser and the interferometer.

The above-described task solution is merely exemplary and should not be construed as limiting the present invention. In addition to the exemplary embodiments described above, there may be additional embodiments described in the drawings and the detailed description of the invention.

According to any one of the above-mentioned means for solving the problems of the present invention, a pump beam irradiated from a pulse laser and a probe beam irradiated from an interferometer portion are incident coaxially to scan a thin film while generating surface waves on the thin film, The defect can be measured. Further, the distance between the pump beam and the probe beam can be controlled according to the position of the pump beam and the probe beam through the reflection mirror.

1 is a view showing a conventional thin film defect detecting apparatus using a pulse laser and an interferometer.
2 is a view for explaining a thin film inspection apparatus according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "electrically connected" with another part in between . Also, when an element is referred to as "comprising ", it means that it can include other elements as well, without departing from the other elements unless specifically stated otherwise.

In this specification, the term " part " includes a unit realized by hardware, a unit realized by software, and a unit realized by using both. Further, one unit may be implemented using two or more hardware, or two or more units may be implemented by one hardware.

In this specification, some of the operations or functions described as being performed by the terminal or the device may be performed in the server connected to the terminal or the device instead. Similarly, some of the operations or functions described as being performed by the server may also be performed on a terminal or device connected to the server.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

2 is a view for explaining a thin film inspection apparatus according to an embodiment of the present invention.

2, the thin film inspection apparatus may include a pulse laser 200, an interferometer unit 202, a reflection mirror 204, a scanning unit 206, and a signal processing unit 208.

The pulsed laser 200 can irradiate a thin film 10 with a pump beam 20 for generating surface waves. When the pump beam 20 is irradiated to the thin film 10, a surface wave is generated in the thin film 10. Such surface waves are waves traveling in a horizontal direction to a thin film in a specific wavelength band, and contain information about the thin film structure. Surface waves can vary in speed depending on the coating material of the thin film and the thickness of the coating layer. The surface wave moves in the vertical direction (Z-axis) at the portion where the sound waves pass because the medium particles move to the elliptical shape.

The interferometer unit 202 can irradiate a probe beam 30 that forms an interferometer from the light emitted from the continuous oscillation laser 210 and measures the surface wave generated in the thin film 10. The probe beam 30 forms an interference fringe in the vicinity of the thin film 10 to which the probe beam 30 is irradiated. Here, the probe beam 30 is used to measure the displacement of the interference pattern due to the surface wave generated in the thin film 10.

The reflection mirror 204 receives the pump beam 20 and the probe beam 30 and can coaxially reflect the pump beam 20 and the probe beam 30. [ The reflection mirror 204 can cause the pump beam 20 and the probe beam 30 to enter the scanning unit 206 at the same time.

For example, the reflection mirror 204 may be composed of a dichroic mirror that separately passes the pump beam 20 and the probe beam 30 having different wavelength bands. The dichroic mirror passes the wavelength range of the probe beam 30 as it is and reflects the wavelength band of the pump beam 20 so that the pump beam 20 and the probe beam 30 are scanned coaxially with the scanning unit 206 Lt; / RTI >

If a general mirror is used instead of the dichroic mirror as the reflection mirror 204, it is difficult to finely adjust the separation distance 40 between the pump beam 20 and the probe beam 30 and the parallel incident light coaxially, The interferometer unit 202 and the scanning unit 206 may be damaged by the pump beam 20 reflected and returned from the thin film 10 in order to measure the characteristics and defects of the substrate 10.

Since the present invention uses only a dichroic mirror as the reflection mirror 204, only the probe beam 30 reflected and returned from the thin film 10 can be passed through to the signal processing unit 208, It is possible to solve the problem that the interferometer unit 202 and the scanning unit 206 are damaged by the beam 20. [

The reflective mirror 204 can control the separation distance 40 between the pump beam 20 and the probe beam 30 depending on the position at which the pump beam 20 and the probe beam 30 are incident. Here, the separation distance 40 may be equal to or less than a distance at which the pulse laser 200 and the interferometer unit 202 can directly irradiate the pump beam 20 and the probe beam 30 to the thin film 10.

As shown in FIG. 1, in the conventional thin film inspection apparatus, since the laser irradiation system 100 and the laser interferometer 110 are installed at a predetermined distance from the transfer unit 120, There is a problem in that it is difficult to control the distance between them. That is, the distance between the surface wave generating point and the receiving unit has to be fixed (for example, several centimeters to several millimeters) depending on the installation position of the laser irradiation system 100 and the laser interferometer 110. [

In particular, due to the physical size of the laser irradiation system 100 and the laser interferometer 110, it is impossible to reduce the distance between the surface wave generation point and the reception unit to a certain distance or less.

However, according to the present invention, the separation distance 40 between the pump beam 20 and the probe beam 30 can be controlled depending on the material of the thin film 10, and accordingly, the distance between the surface wave generation point and the reception unit 50 ) Is also controlled. For example, since the decay rate of stainless steel is fast, the separation distance 40 between the pump beam 20 and the probe beam 30 is narrowed. In the case of aluminum and iron, the decay rate is low. Therefore, the pump beam 20 and the probe beam 30, The spacing distance 40 between the two electrodes 30 can be relatively widened.

Particularly, according to the present invention, the distance 40 between the pump beam 20 and the probe beam 30 can be increased or decreased regardless of the physical size of the pulse laser 200 and the interferometer portion 202. For example, the separation distance can be reduced to 0 to 5 mm or less, which is not possible in a conventional thin film inspection apparatus.

The characteristics and defects of the thin film 10 having various materials can be measured by controlling the separation distance 40 between the pump beam 20 and the probe beam 30 through the reflection mirror 204. By controlling the incident positions of the pump beam 20 and the probe beam 30 from the pulse laser 200 and the interferometer unit 202, the separation distance 40 between the pump beam 20 and the probe beam 30 is set to It can be easily controlled.

The scanning unit 206 receives the pump beam 20 and the probe beam 30 reflected coaxially and irradiates the thin film 10 with the pump beam 20 and the probe beam 30 to scan the thin film 10 can do.

The scanning unit 206 may be, for example, a galvanometer. The galvanometer may include a first mirror 212 and a second mirror 214 that reflect the incident pump beam 20 and the probe beam 30 in directions different from the incident direction. The galvanometer may irradiate the thin film 10 with the pump beam 20 and the probe beam 30 having the separation distance 40 by using mutual reflection angles of the first mirror 212 and the second mirror 214 The thin film 10 can be scanned.

When the surface wave generated by the pump beam 20 passes the interference pattern formed by the probe beam 30, an instantaneous change in the interference pattern (the surface vibrates finely in the Z axis direction due to the movement of the surface wave medium particles) The scanning unit 206 may scan the interference pattern displacement data and transmit it to the signal processing unit 208. [

The signal processing unit 208 can measure the velocity, thickness, and the like of surface waves by converting displacement data of the interference pattern into voltage values. For example, the signal processing section 208 can calculate the surface wave velocity using the irradiation time of the pulse laser 200 and the displacement data of the interference pattern. Here, the velocity of the surface wave is greatly influenced by the density and the elastic modulus of the medium of the thin film 10. For example, the surface wave velocity is accelerated at a point where the thickness of the thin film 10 changes rapidly (for example, when cracks and pores near the surface are generated and the thickness of the thin film 10 is thin).

The signal processing section 208 can measure the characteristics and defects of the thin film 10 based on the calculated surface wave velocity.

The pump beam 20 and the probe beam 30 are incident coaxially to simultaneously scan the thin film 10 to measure the characteristics and defects of the thin film 10, It is possible to solve the problem of a reflected noise signal and the like.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

It is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. .

200: Pulsed laser
202: interferometer unit
204: reflection mirror
206: Scanning section
208:
210: continuous oscillation laser

Claims (5)

  1. A thin film inspection apparatus for measuring characteristics and defects of a thin film,
    A pulse laser for irradiating a pump beam for generating a surface wave on the thin film;
    An interferometer for forming an interferometer from the light emitted from the continuous oscillation laser and irradiating a probe beam for measuring a surface wave generated in the thin film;
    A reflection mirror for receiving the pump beam and the probe beam, and coaxially reflecting the pump beam and the probe beam;
    A scanning unit for receiving the pump beam and the probe beam reflected by the coaxial axis and scanning the thin film by irradiating the pump beam and the probe beam onto the thin film; And
    A signal processor for measuring characteristics and defects of the scanned thin film,
    , ≪ / RTI &
    Wherein a distance between the pump beam and the probe beam irradiated to the thin film is controlled by controlling an incident position of at least one of the pump beam irradiated by the interferometer unit and the probe beam irradiated by the pulse laser to the reflection mirror The thin film inspection apparatus comprising:
  2. The method according to claim 1,
    The reflection mirror is a dichroic mirror,
    Wherein the dichroic mirror passes the probe beam and reflects the pump beam.
  3. The method according to claim 1,
    Wherein the reflection mirror is configured to control a separation distance between the pump beam and the probe beam according to a position at which the pump beam and the probe beam are incident.
  4. The method of claim 3,
    The scanning unit is a galvanometer,
    Wherein the galvanometer irradiates the pump beam and the probe beam having the separation distance to the thin film to scan the thin film.
  5. The method of claim 3,
    Wherein the separation distance is not more than a distance at which the pump beam and the probe beam can be directly irradiated to the thin film by the pulse laser and the interferometer.
KR1020160176372A 2016-12-22 2016-12-22 Apparatus for detecting characteristics and defect of thin-film KR101875058B1 (en)

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KR1020160176372A KR101875058B1 (en) 2016-12-22 2016-12-22 Apparatus for detecting characteristics and defect of thin-film
PCT/KR2017/005669 WO2018117350A1 (en) 2016-12-22 2017-05-31 Thin film inspection device for measuring characteristic and defect of thin film

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4541280A (en) * 1982-12-28 1985-09-17 Canadian Patents & Development Ltd. Efficient laser generation of surface acoustic waves
US5633711A (en) * 1991-07-08 1997-05-27 Massachusettes Institute Of Technology Measurement of material properties with optically induced phonons
US20060215175A1 (en) * 2004-07-28 2006-09-28 Ler Technologies, Inc. Surface and subsurface detection sensor
US20070273952A1 (en) * 2004-03-23 2007-11-29 Murray Todd W Characterization of Micro- and Nano Scale Materials By Acoustic Wave Generation With a Cw Modulated Laser
US20090168074A1 (en) * 2006-05-10 2009-07-02 Jean-Pierre Monchalin Method of Assessing Bond Integrity in Bonded Structures

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4541280A (en) * 1982-12-28 1985-09-17 Canadian Patents & Development Ltd. Efficient laser generation of surface acoustic waves
US5633711A (en) * 1991-07-08 1997-05-27 Massachusettes Institute Of Technology Measurement of material properties with optically induced phonons
US20070273952A1 (en) * 2004-03-23 2007-11-29 Murray Todd W Characterization of Micro- and Nano Scale Materials By Acoustic Wave Generation With a Cw Modulated Laser
US20060215175A1 (en) * 2004-07-28 2006-09-28 Ler Technologies, Inc. Surface and subsurface detection sensor
US20090168074A1 (en) * 2006-05-10 2009-07-02 Jean-Pierre Monchalin Method of Assessing Bond Integrity in Bonded Structures

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WO2018117350A1 (en) 2018-06-28

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