WO2023163480A1

WO2023163480A1 - Inspection apparatus using terahertz waves

Info

Publication number: WO2023163480A1
Application number: PCT/KR2023/002443
Authority: WO
Inventors: 김장선; 조수영; 김이섭; 고상주; 김선재; 박민우; 안영환
Original assignee: (주)팬옵틱스
Priority date: 2022-02-22
Filing date: 2023-02-21
Publication date: 2023-08-31
Also published as: KR20230125991A; KR102638751B1

Abstract

An inspection apparatus using terahertz waves is disclosed. One aspect of the present embodiment provides an inspection apparatus using terahertz waves, which is an inspection apparatus for inspecting the structure or state of an object in a black box, comprising: a light source that irradiates a beam of a terahertz frequency band; a reflector that reflects the beam irradiated from the light source to an object, and reflects the light reflected from the object back toward the light source; a lens unit that focuses the beam reflected by the reflector onto the object; a light receiving unit that receives a beam reflected from the object; an inspection unit that analyzes the reflected beam received from the light receiving unit and inspects the structure or state of the object; a beam splitter that passes the beam irradiated from the light source and reflects the light reflected from the reflector to the light receiving unit after being reflected from the object; and a control unit that controls operations of the light source, the reflector, and the inspection unit.

Description

Inspection device using terahertz waves

The present invention relates to an apparatus for inspecting an object such as a semiconductor using terahertz waves.

The contents described in this part merely provide background information on the present embodiment and do not constitute prior art.

In general, a semiconductor chip is a core component required by computers, all electronic products, and information processing products, and performs arithmetic operations, information storage/transmission, and control of other chips.

In particular, the semiconductor chip may be implemented as a very miniaturized plastic packaging chip having a size of about 10X10mm ² . Due to this, it is almost impossible for an inspector to visually identify defects such as cracks, peelings, and voids in packaged semiconductor chips.

Recently, a method of inspecting a semiconductor chip or the like using terahertz waves has emerged. A method using terahertz waves radiates terahertz electromagnetic waves to an object, and compares an electrical signal generated based on the terahertz electromagnetic waves reflected from the object with a reference signal to analyze the object.

However, in the conventional inspection method, inspection was possible only when electromagnetic waves were directly irradiated onto an object and then reflected therefrom. Therefore, there is a problem in that it is difficult to inspect the object when the object disposed in the black box or the outside is separately sealed or shielded.

An object of one embodiment of the present invention is to provide an apparatus for inspecting the structure or state of an object existing in a black box using terahertz waves.

According to one aspect of the present invention, in the inspection apparatus for inspecting the structure or state of an object in a black box, a light source for irradiating a beam of a terahertz frequency band and a beam emitted from the light source are reflected to the object, and the object The light reflected from the reflector for reflecting back toward the light source, the lens unit for focusing the beam reflected from the reflector to the object, the light receiver for receiving the beam reflected from the object, and analyzing the reflected beam received from the light receiver An inspection unit that inspects the structure or state of an object, a beam splitter that passes the beam emitted from the light source, and reflects the light reflected from the object and then reflected from the reflector to the light receiver, and the light source, the reflector, and the inspection unit Provided is a terahertz wave inspection device characterized in that it includes a control unit for controlling the operation.

According to one aspect of the present invention, the reflector is characterized in that implemented as a galvano mirror.

According to one aspect of the present invention, the inspection unit is characterized in that the conversion of the reflected beam received by the light receiving unit into a complex number dimension.

According to one aspect of the present invention, the inspection unit is characterized in that the amplitude function and phase function of the reflected beam is calculated using the reflected beam received by the light receiving unit and the reflected beam converted to a complex number dimension.

According to one aspect of the present invention, the inspection unit is characterized in that the structure or state of the object is inspected using the calculated phase function of the reflected beam.

According to one aspect of the present invention, the inspection unit is characterized in that to remove noise in the reflected beam signal.

According to one aspect of the present invention, the inspection unit is characterized in that the noise is removed by removing the phase information of the portion where the reflected beam signal does not exist.

According to one aspect of the present invention, the beam splitter is characterized in that it is disposed on the light path formed by the light source and the reflector.

According to one aspect of the present invention, the beam splitter is characterized in that the reflective surface is disposed toward the light receiving unit.

As described above, according to one aspect of the present invention, even if the object exists in the black box or is separately sealed or shielded on the outside of the object, the structure or state of the object in that state using terahertz waves has the advantage of being able to inspect

1 is a diagram showing the configuration of a terahertz wave inspection apparatus according to an embodiment of the present invention.

2 is a diagram illustrating a state in which a path of a beam output by a reflector according to an embodiment of the present invention changes.

3 is a diagram showing the configuration of an inspection unit according to an embodiment of the present invention.

4 is a graph showing phase information of an object for recognizing an object by an object recognition unit according to an embodiment of the present invention.

Since the present invention can make various changes and have various embodiments, specific embodiments will be illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, or substitutes included in the spirit and technical scope of the present invention. Like reference numerals have been used for like elements throughout the description of each figure.

Terms such as first, second, A, and B may be used to describe various components, but the components should not be limited by the terms. These terms are only used for the purpose of distinguishing one component from another. For example, a first element may be termed a second element, and similarly, a second element may be termed a first element, without departing from the scope of the present invention. The terms and/or include any combination of a plurality of related recited items or any of a plurality of related recited items.

It is understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, but other elements may exist in the middle. It should be. On the other hand, when an element is referred to as “directly connected” or “directly connected” to another element, it should be understood that no intervening element exists.

Terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. It should be understood that terms such as "include" or "having" in this application do not exclude in advance the possibility of existence or addition of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification. .

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in the present application, they should not be interpreted in an ideal or excessively formal meaning. don't

In addition, each configuration, process, process or method included in each embodiment of the present invention may be shared within a range that does not contradict each other technically.

Referring to FIG. 1 , a terahertz wave inspection apparatus 100 according to an embodiment of the present invention includes a light source 110, a beam splitter 120, a reflector 130, a lens unit 140, a light receiving unit 160, It includes an inspection unit 170 and a control unit (not shown).

The terahertz wave inspection apparatus 100 irradiates a beam of a frequency band of terahertz (0.1 to several tens of THz) to an object, receives and analyzes a reflected beam reflected therefrom, and recognizes the structure or state of the object. In particular, the terahertz wave inspection apparatus 100 extracts the amplitude and phase of the reflected beam, and recognizes the structure or state of the object from the extracted phase. Since the terahertz wave inspection apparatus 100 uses the phase of the reflected beam, even if the object is disposed in a black box or a separate (having a certain purpose) exterior material, even if the object is disposed in the exterior material, it is distinguished from the exterior material. The structure or state of an object can be recognized.

The object to be inspected may be a semiconductor chip, but is not necessarily limited thereto, and may be replaced with any material that receives and reflects a beam of the terahertz frequency band.

The light source 110 radiates a terahertz frequency band beam to the reflector 130 . The light source 110 generates a beam with a frequency of 0.1 to tens of terahertz (Hz) and a wavelength band of tens to hundreds of μm and irradiates the beam with the reflector 130 . A beam irradiated onto an object is reflected to have a unique phase according to the structure or state of the object. Accordingly, the phase of the reflected beam may include information on the unique structure or state of the object.

The beam splitter 120 passes a beam traveling from the light source 110 to itself, but reflects a beam reflected from the reflector 130 and traveling towards itself. The beam splitter 120 is disposed so that its reflective surface faces the light receiving unit 160 on the light path formed by the light source 110 and the reflector 130 . Accordingly, the beam splitter 120 passes the beam irradiated from the light source 110 to the reflector 130, and reflects the reflected beam reflected from the object and reflected from the reflector 130 to the light receiver 160.

The reflector 130 reflects a beam incident thereto at a predetermined angle.

The reflector 130 is disposed at a point of contact between the path between itself and the light source 110 and between itself and the object 155, and reflects a beam traveling on one path to the other path. For example, the reflector 130 reflects a beam irradiated from the light source 110 and incident to itself through the beam splitter 120 toward an object 155, and a beam reflected from the object 155 and incident to itself. is reflected toward the beam splitter 120.

The reflector 130 may adjust a reflection angle of an incident beam under the control of a controller (not shown). The operation of reflector 130 is shown in FIG. 2 .

As shown in FIGS. 2A to 2C , the reflector 130 may adjust a reflection angle of an incident beam under the control of a controller (not shown). When the reflection angle of the reflector 130 is adjusted, a traveling path of a beam incident to the reflector 130 may be adjusted. 2a, the beam irradiated from the light source 110 by the reflector 130 may be irradiated to the center of the object 155, or may be irradiated to the end of the object 155 as shown in FIGS. 2b or 2c. In addition, the reflector 130 reflects the reflected beam reflected from the object 155 after being irradiated at the corresponding angle toward the beam splitter 120 .

The reflector 130 may adjust the angle of reflection under the control of a controller (not shown), so that beams may be incident to various positions of the object 155 . The terahertz wave inspection apparatus 100 includes the reflector 130, so that the fixed object 155 can be scanned in two dimensions. For two-dimensional scanning of an object, a conventional inspection device has been scanning while moving a cradle on which an object is mounted. However, when scanning is performed while moving the cradle, there is a problem in that it is difficult to secure a sufficient scanning speed. The terahertz wave inspection apparatus 100 includes a reflector 130 and adjusts an angle of the reflector 130 to perform two-dimensional scanning of an object without moving the cradle.

Referring back to FIG. 1 , the reflector 130 may be implemented as a galvano mirror, but is not necessarily limited thereto, and may be replaced with anything as long as the reflection angle can be controlled.

The lens unit 140 focuses the beam reflected by the reflector 130 onto an object 155 . The lens unit 140 is positioned between the reflector 130 and the light path of the object 155, and adjusts the path of the beam so that the beam reflected from the reflector 130 proceeds to the object 155 without being dispersed. As shown in FIG. 1 , the lens unit 140 may be implemented as a single lens, but is not necessarily limited thereto, and may be implemented as a combination of a plurality of lenses. For example, the lens unit 140 may be implemented as an f-θ lens or a collimator.

The light receiving unit 160 receives the reflected beam reflected from the target object 155 . The light receiving unit 160 is implemented as an optical sensor and senses a reflected beam that is reflected from the object 155 and is incident thereon through the reflector 130 and the beam splitter 120 . As the light receiving unit 160 senses the reflected beam, the inspecting unit 170 can recognize the structure or state of the object based on the sensed value.

The inspection unit 170 extracts phase information of the object from the reflected beam (sensing value) and inspects the structure or state of the object. The inspection unit 170 converts the reflected beam into a complex dimension, and calculates the amplitude and phase of the reflected beam using the converted value. The inspection unit 170 finally recognizes the structure or state of the object after removing the area where the object exists and the area where the object does not exist, that is, noise. A specific configuration of the inspection unit 170 is shown in FIG. 3 .

Referring to FIG. 3 , the inspection unit 170 according to an embodiment of the present invention includes a reflection beam conversion unit 310 , a noise removal unit 320 and an object recognition unit 330 .

The reflected beam conversion unit 310 converts the reflected beam into a complex number dimension. A reflected beam sensed by the light receiver 160 corresponds to a real dimension. The reflected beam conversion unit 310 goes through the following process and converts the real-dimensional reflected beam into a complex-numbered dimension.

The reflected beam conversion unit 310 converts the reflected beam into a complex number dimension based on the above equation, and obtains an amplitude function and a phase function of the reflected beam using the following equation.

Here, A(t) is the amplitude function of the reflected beam, Φ(t) is the phase function of the reflected beam, f _real (t) is the reflected beam in real dimension, and f _img (t) is the transformed complex dimension means reflected beam.

The reflected beam conversion unit 310 goes through the above process and calculates an amplitude function and a phase function of the reflected beam from the (real dimension) reflected beam sensed by the light receiving unit 160 .

The noise removal unit 320 removes noise by removing phase information of a portion where the reflected beam signal does not exist. The noise removal unit removes noise as follows.

Here, a function with an upper bar means a normalized function. When the phase function of the reflected beam is multiplied by the normalized amplitude function (of the reflected beam), the phase function of the final reflected beam obtained by removing the phase information of the portion where the reflected beam signal does not exist is calculated as described above.

The object recognition unit 330 recognizes the object from the phase function finally calculated by the noise removal unit 320 . The finally calculated phase function of the reflected beam is shown in FIG. 4 .

The object recognizing unit 330 calculates the remaining phase values as relative values of the reference based on the phase value of any one point from the finally calculated phase function. In the phase function shown in FIG. 4, point 410 is the top of the black box (eg, cover), point 420 is the bottom of the black box, point 430 is the top (surface) of the object, and point 440 is the top of the black box. At the lower end of the object, point 450 may indicate a void or other material generated in the object. At this time, the object recognizing unit 330 uses a point in the phase function of the finally calculated reflected beam, for example, the topmost point 410 of the black box as a reference (for example, designates as π / 2), The remaining points 420 to 450 may be expressed as relative values of the reference. In this case, in recognizing the object 155 in the black box 150, the object recognizing unit 330 does not need to calculate the absolute phase value of each point, so the calculation process can be significantly reduced.

Since the point 420 is implemented with a relatively small medium based on the point 410, it can be seen that the phase value is relatively small compared to the point 410. It is confirmed that there is no separate phase value because there is a blank between the

points

420 and 430, and the phase value at the point 430 is relatively significantly higher because a relatively dense medium exists therefrom. Similarly, point 440 has a relatively small phase value compared to point 430 because it is implemented with a smaller medium.

Accordingly, the inspection unit 170 may determine whether the object 155 exists in the black box and what the structure or state of the object 155 is by using the phase function. Since scanning can be performed on all parts of the object by two-dimensional scanning of the reflector 130, the structure or state of all parts of the object 155 can be confirmed.

In addition, the inspection unit 170 may check whether a gap has occurred in the object 155 or whether a separate component such as an adhesive component such as epoxy is included using the phase function. For example, when points having different phase values, such as point 450, exist within the object 155, the inspection unit 170 may anticipate the above-described case. At this time, if the phase value is the same as the phase value between the point 420 (one end of the black box) and the point 430 (the surface of the object), the corresponding part corresponds to a gap. Conversely, if the phase value is different from

points

430 and 440 and also different from the phase value between point 420 (one end of the black box) and point 430 (surface of the object), the corresponding part is a separate component within the object 155. (eg, adhesive composition such as epoxy).

As such, the inspection unit 170 can accurately grasp the structure or state of the object in the black box as it is without complicated calculation by using the phase function.

Referring back to FIG. 1 , a controller (not shown) controls the operation of each component.

A controller (not shown) controls the light source 110 to emit a beam.

The controller (not shown) controls the reflector 130 to scan the object 155 in two dimensions.

The controller (not shown) controls the inspector 170 to check the structure or state of the object based on the value sensed by the light receiver 160 .

The above description is merely an example of the technical idea of the present embodiment, and various modifications and variations can be made to those skilled in the art without departing from the essential characteristics of the present embodiment. Therefore, the present embodiments are not intended to limit the technical idea of the present embodiment, but to explain, and the scope of the technical idea of the present embodiment is not limited by these embodiments. The scope of protection of this embodiment should be construed according to the claims below, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of rights of this embodiment.

CROSS-REFERENCE TO RELATED APPLICATION

If this patent application claims priority in accordance with U.S. Patent Act Article 119 (a) (35 U.S.C § 119 (a)) for Patent Application No. 10-2022-0022916 filed in Korea on February 22, 2022, that All contents are incorporated into this patent application by reference. In addition, if this patent application claims priority for the same reason as above for countries other than the United States, all the contents are incorporated into this patent application as references.

Claims

In the inspection device for inspecting the structure or state of an object in a black box,

a light source irradiating a beam of a terahertz frequency band;

a reflector for reflecting the beam irradiated from the light source to the object, and reflecting the light reflected from the object back toward the light source;

a lens unit for focusing the beam reflected by the reflector onto the object;

a light receiving unit for receiving a beam reflected from the object;

an inspection unit for inspecting a structure or state of an object by analyzing the reflected beam received by the light receiving unit;

a beam splitter for passing the beam irradiated from the light source and reflecting the light reflected from the reflector after being reflected from the object to the light receiving unit; and

A control unit for controlling operations of the light source, the reflector, and the inspection unit

Terahertz wave tester comprising a.
According to claim 1,

The reflector is

A terahertz wave inspection device, characterized in that implemented as a galvano mirror.
According to claim 1,

the inspection department.

The terahertz wave inspection device characterized in that for converting the reflected beam received by the light receiving unit into a complex number dimension.
According to claim 3,

The inspector,

The terahertz wave inspection apparatus according to claim 1 , wherein an amplitude function and a phase function of the reflected beam are calculated using the reflected beam received by the light receiving unit and the reflected beam converted into a complex number dimension.
According to claim 4,

The inspector,

A terahertz wave inspection device, characterized in that for inspecting the structure or state of an object by using the phase function of the calculated reflected beam.
According to claim 4,

The inspector,

A terahertz wave inspection device characterized in that for removing noise in the reflected beam signal.
According to claim 6,

The inspector,

A terahertz wave inspection apparatus characterized in that noise is removed by removing phase information of a portion where a reflected beam signal does not exist.
According to claim 1,

The beam splitter,

The terahertz wave inspection device, characterized in that disposed on the light path formed by the light source and the reflector.
According to claim 8,

The beam splitter,

A terahertz wave inspection device, characterized in that the reflective surface is disposed facing the light receiving unit.