KR20210051865A - Measuring system using terahertz spectroscopy - Google Patents

Abstract

The present invention relates to a system capable of measuring the thickness and physical properties (electrical conductivity, doping concentration, resistance) of a thin film formed on a measurement object by irradiating a terahertz wave onto a measurement object and spectroscopic analysis of the reflected wave. It relates to a measurement system capable of increasing measurement efficiency by increasing the beam power output of the reflected wave by controlling the bandwidth of the terahertz wave reflected from the object to be measured by adjusting the rotation angle and height of the beam irradiation unit that irradiates the terahertz at low temperature.

Description

Measurement system based on terahertz wave spectroscopy technology {MEASURING SYSTEM USING TERAHERTZ SPECTROSCOPY}

The present invention relates to a measurement system based on a terahertz wave spectroscopy technology, and more specifically, by irradiating a terahertz wave onto a measurement object and spectroscopically analyzing the reflected wave, the thickness and physical properties of a thin film formed on the measurement object (electrical conductivity, It relates to a system capable of measuring doping concentration, resistance)

Epitaxial wafers for semiconductors are products in which a silicon single crystal layer is additionally deposited or ion-doped in a thickness of several μm on the polished wafer. As the demand for semiconductor devices such as microprocessors, image sensors, and power devices increases, the production volume continues. Is increasing.

The epi layer plays an important role in controlling the electrical conductivity when making a semiconductor device, and is a relatively low concentration of n or p type through ion implantation or CVD method on an n+ or p+ type high doped Si wafer. It forms a layer.

In this way, the thickness is 2~80um, and the doping concentration is ^{between 10 14} ~ 10 ¹⁸ , according to the customer's requirements.

Existing wafer measuring devices have a disadvantage in that it is difficult to accurately measure the thickness or doping concentration of an epiwafer in units of several um, or to measure quickly.

Registered Patent Publication No. 10-1788450

An object of the present invention is to provide a measuring system capable of accurately measuring the thickness and doping concentration of a thin film.

In addition, an object of the present invention is to provide a measuring system capable of measuring the thickness and doping concentration of a thin film at the same time.

In addition, an object of the present invention is to provide a measurement system capable of maximizing the intensity of a terahertz wave, which is a reflected wave, by adjusting the angle of incidence and focusing of a terahertz wave irradiated onto a thin film.

The measurement system according to an embodiment of the present invention includes a beam generator 100 that generates a pulsed wave shape beam, and divides the pulsed wave shape beam into a first femtosecond pulse 210 and a second femtosecond pulse 220 A beam splitting unit 200 to perform, a beam irradiating unit 300 receiving the first femtosecond pulse 210 divided by the beam splitting unit 200 and converting it to a terahertz wave to irradiate the measurement object, the beam irradiating unit 300 The terahertz wave irradiated from the measurement object is reflected from the measurement object, the beam detector 500 receiving the terahertz wave reflected from the measurement object and the second femtosecond pulse 220 divided by the beam splitter 200, the beam A beam alignment unit 400 for controlling the bandwidth of the reflected terahertz wave by adjusting the rotation angle and height of the irradiation unit 300 may be included.

In addition, the beam irradiation unit 300 receives the first femtosecond pulse 210, converts it into a terahertz wave, and emits a terahertz emitter 310, and the terahertz wave emitted from the terahertz emitter 310 A first optical unit 320 for collimating, and a second optical unit 330 for focusing terahertz waves collimated by the first optical unit 320 may be included.

In addition, the beam detection unit 500 receives and collimates the terahertz wave reflected from the object to be measured, and the third optical unit 510 collimates the terahertz wave collimated by the third optical unit 510. 4 The optical unit 520 may include a beam detector 530 that detects the terahertz wave focused by the fourth optical unit 520 and the second femtosecond pulse 220 divided by the beam splitter 200. have.

In addition, the beam irradiation unit 300 includes a first rail unit 340 capable of adjusting the arrangement of the terahertz emitter 310, the first optical unit 320, and the second optical unit 330 can do.

In addition, the beam detection unit 500 may include a second rail unit 540 capable of adjusting the arrangement of the third optical unit 510, the fourth optical unit 520, and the beam detector 530. have.

In addition, the beam alignment unit 400 may include an angle adjustment unit 410 that adjusts the incident angle of the terahertz wave irradiated from the beam irradiation unit 300.

In addition, the beam alignment unit 400 may further include a focusing adjustment unit 420 that adjusts the focusing of terahertz waves irradiated by the beam irradiation unit 300.

In addition, the angle adjusting part 410 includes a first vertical part 411, a first LM block 412, a second vertical part 414, a second LM block 415, and a first round LM guiding part 416. ), a second round LM guiding unit 417 and a first guiding unit 418 may be included.

In addition, the first round LM guiding portion 416 and the second round LM guiding portion 417 protrude from the first surface of the first guiding portion 418 with a first radius of curvature, and the first round LM guiding portion Reference numeral 416 is formed in a direction opposite to the second round LM guiding portion 417, and the first round LM guiding portion 416 includes the first LM block 412 of the first guiding portion 418. Guiding the movement to draw a rotational trajectory along an arc on one side, and in the second round LM guiding part 417, the second LM block 415 rotates along an arc on one side of the first guiding part 418 The first LM block 412 and the second LM block 415 are guided to move while drawing a trajectory, and the first round LM is reduced on one surface of the first LM block 412 and the second LM block 415 while reducing friction with one surface of the first guiding part 418. A guiding part 416 and at least one ball movable along the second round LM guiding part 417 may be included.

In addition, the angle adjusting part 410 may further include a second guiding part 419 disposed on the second surface of the first guiding part 418.

In addition, the second surface of the first guiding part 418 and the first surface of the second guiding part 419 face each other, and the second guiding part 419 has a rotating part 419a, a screw part 419b, Link base 419c, first link arm 419d, second link arm 419e, first LM guide 419f, second LM guide 419g, first hole 419h, second hole 419i ) Can be included.

In addition, the rotating part 419a rotates clockwise or counterclockwise, and the screw part 419b is connected to the rotating part 419a, converting the rotational motion of the rotating part 419a into linear motion, and the link base 419c ) Moves up and down, and the second end of the first link arm 419d passes through the first hole 419h having a round cross section, and the first LM block 412 or the first vertical portion ( 411, the second end of the second link arm 419e passes through the second hole 419i having a round cross section and is attached to the second LM block 415 or the second vertical portion 414 Can be fixed.

In addition, the link base (419c) is guided to the first LM guide (419f) and the second LM guide (419g) and elevating, the beam irradiation unit ( 300) moves in a first clockwise direction, and the beam detector moves in a second clockwise direction, but the moving angle of the rotational trajectory in which the beam irradiation unit 300 and the beam detection unit 500 move and the length of the arc may be the same. I can.

In addition, the focusing adjustment unit 420 is disposed on the second surface of the second guiding unit 419 and is connected to a part of the second surface of the second guiding unit 420 to provide a height of the second guiding unit. Can be adjusted.

In addition, the measurement system further includes a beam controller 600, the beam detector 530 transmits the terahertz wave reflected from the measurement object to the beam controller 600, the beam controller 600 Converts the reflected terahertz wave waveform into the frequency domain, and controls the rotational trajectory of the first LM block 412 and the vertical movement distance of the second guiding unit so that the bandwidth of the transformed terahertz wave is minimized It is possible to generate a control signal.

In addition, the measurement system further includes a fixing unit 700 for fixing the second surface of the focusing control unit 420 and a stage 800 capable of mounting and transferring the measurement object, and the fixing unit 700 ) And the stage 800 are disposed on the upper surface of the seokjeongban 700, the beam irradiation part 300, the beam detection part 500, the beam alignment part 400, which are disposed above the seokjeongban 700, It may include a chamber 1000 forming a space that seals the measurement object, the fixing part 700, and the stage 800.

In addition, the chamber 1000 includes an air injection unit and an air discharge unit, and the air injection unit is an air supply unit 1300 for driving to supply dry air into the chamber 1000-the air supply unit 1300 It is connected to the chamber 1000 disposed outside-and the air discharge unit may discharge air inside the chamber 1000 to the outside.

In addition, the measurement system further includes a humidity sensor and a humidity control unit, wherein the humidity sensor detects the humidity inside the chamber 1000 and transmits the detected humidity information to the humidity control unit, and the humidity control unit includes the humidity control unit. Based on the received humidity information, a control signal for controlling the amount of dry air injected into the air injection unit so that the humidity inside the chamber 1000 is within a predetermined range may be generated and transmitted to the driving unit of the air supply unit 1300. .

In addition, the humidity control unit controls the driving of the air supply unit 1300 so that the humidity inside the chamber 1000 is 5% or less, and turns on and off a valve that is connected to the air supply unit to deliver dry air into the chamber. Can be controlled.

The present invention can provide a measurement system capable of accurately measuring film thickness and electrical conductivity with a high degree of precision required by a wafer epitaxial layer for mass production.

The present invention can also be used as a measuring instrument for in-situ monitoring of film forming equipment such as CVD (Chemical Vapor Deposition) and ALD (Atomic Layer Deposition).

The present invention can also be used as a system for quickly measuring the uniformity of electrical conductivity over the entire area for products whose electrical properties are important, such as ITO (Indium Tin Oxide) or graphene.

The present invention can also reduce cost and space occupied by equipment by integrating a plurality of measuring instruments purchased at a high price into one.

If the present invention is used, quality control can be performed early through in-line monitoring of the semiconductor manufacturing process, thereby reducing the semiconductor defect rate, thereby contributing to reducing waste of core materials such as rare earths.

1 is a diagram showing a frequency domain of a terahertz (THz) wave.
2 is a graph showing a difference in absorption rate and absorption rate for each frequency according to the silicon doping concentration.
3 is a diagram schematically showing the behavior of incident waves and reflected waves of terahertz wave pulses in an epi layer.
4 is a diagram showing a relationship between a beam generator, a beam irradiation unit, a beam splitter, and a beam detection unit
5 is a view showing a beam alignment unit
6 to 9 are views showing a beam angle adjustment unit
10 is a block diagram of a beam controller
11 is a diagram showing a measurement system not including a chamber
12 is a diagram showing a measurement system including a chamber
13 is a diagram showing a humidity control system for controlling the humidity inside the chamber.
14 is a diagram showing a reflected wave before humidity control
15 is a diagram showing a reflected wave after humidity control.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, when a part is said to be "connected" to another part, it is not only "directly connected", but also "electrically or communicatively connected" with another element in between. Also includes. In addition, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless specifically stated to the contrary.

Hereinafter, the apparatus and method of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, the terahertz wave has a terahertz frequency of 10 ¹² to 10 ¹⁴ Hz in a section between infrared and electromagnetic waves, and has a characteristic in which the amount of transmission and the amount of reflection vary according to the electrical characteristics of the object. Moreover, there is an advantage in that it is possible to transmit even an opaque sample that is not transmitted by general light, and that the thickness of a thin thin film layer can be measured because the wavelength is shorter than that of the radio frequency.

FIG. 2 shows the relationship between the absorption rate of the electromagnetic wave for each frequency in the high-doped Si and the low-doped Si in the silicon wafer, and it can be seen that the difference in the absorption rate is the largest in the terahertz wave region. As can be seen in FIG. 2, since the terahertz wave has a characteristic that the absorption rate varies greatly depending on the doping concentration of the epitaxial layer doped on the silicon wafer, the doping concentration (electrical conductivity) can be measured with high sensitivity.

The present invention irradiates a terahertz wave to an epiwafer sample, and analyzes the reflected wave by using the fact that the reflected wave varies depending on the physical properties of the epi layer and the substrate layer and the characteristics of the interface. Provides a measuring system that can accurately measure (electrical conductivity, doping concentration, and resistance).

However, the object to be measured in the measurement system according to an embodiment of the present invention is not necessarily limited to the epiwafer, and may also be used when measuring various physical or chemical properties of a different thin film thickness, ion doping concentration, and object. I can.

The measurement system according to an embodiment of the present invention includes a beam generating unit 100, a beam splitting unit 200, a beam irradiating unit 300, a beam aligning unit 400, a beam detecting unit 500, a beam controlling unit 600, A humidity sensor 1100 and a humidity control unit 1200 may be included.

<Beam generator 100>

The beam generator 100 according to an exemplary embodiment of the present invention generates a pulse wave type beam. Preferably, the beam generator 100 may be a femtosecond pulse laser source.

<Beam splitting part 200>

The femtosecond pulse emitted from the femtosecond pulse light source according to an embodiment of the present invention is divided into a first femtosecond pulse 210 and a second femtosecond pulse 220 by the beam splitter 200. The second femtosecond pulse 220 is guided to the beam detection unit 500 to function as a probe beam, and the first femtosecond pulse 210 is delayed for a predetermined time through a delay stage. Then, it is input to the beam irradiation unit 300.

<Beam irradiation unit 300>

The beam irradiation unit 300 according to an embodiment of the present invention may include a terahertz emitter 310, a first optical unit 320, and a second optical unit 330.

The terahertz emitter 310 receives the first femtosecond pulse 210 and emits the terahertz pulse to the first optical unit 320. The terahertz emitter 310 is connected to the delay stage through an optical fiber, and receives a first femtosecond pulse 210 from the delay stage through the optical fiber.

The first femtosecond pulse 210 passed through the delay stage is irradiated to the terahertz emitter 310 to function as a pump light for generating terahertz wave pulses. After the first femtosecond pulse 210 is irradiated to a THz emitter including a photoconductive antenna (PCA), a terahertz wave pulse is generated.

The terahertz wave pulse generated by the terahertz emitter 310 is collimated by the first optical unit 320 and transmitted to the second optical unit 330. The second optical unit 330 focuses the collimated terahertz wave pulse and irradiates it to a specific position of the measurement object (sample).

In addition, the beam irradiation part 300 may further include a first rail part 340 in a bar shape. On one surface of the first ray part 340, the terahertz emitter 310, the first optical part 320, and the second optical part 330 are arranged in a line so that the optical axes coincide, and the distance between them can be adjusted. have.

The terahertz wave pulse output from the beam irradiation unit 300 to the object to be measured is irradiated to a specific position of the object to be measured, reflected at the interface of the object to be measured, and then transmitted to the beam detector 500. Preferably, the terahertz wave pulse is irradiated to a specific location of the sample, reflected at the upper and lower interfaces of the epi layer, and then transmitted to the beam detector 500.

<Beam detection unit 500>

The beam detection unit 500 may include a third optical unit 510, a fourth optical unit 520, and a beam detector 530.

The beam detector 500 may receive the terahertz wave reflected from the measurement object and the second femtosecond pulse 220 divided by the beam splitter 200.

The third optical unit 510 receives the terahertz wave pulse reflected from the measurement object, collimates it, and outputs it. The fourth optical unit 520 focuses the terahertz wave pulse collimated and output from the third optical unit 510 and guides it to the beam detector 530.

The beam detector 530 detects the guided and transmitted terahertz wave.

The second femtosecond pulse 220 functioning as a probe beam reaches the beam detector 530 before the terahertz wave reflected by the object to be measured and serves to set a reference point of time for detecting the terahertz wave.

According to an embodiment, the terahertz wave pulse output from the beam irradiation unit 300 is irradiated to a sample and transmitted through the first reflected wave (reflectance R ₁₂ ) reflected from the upper surface of the epi layer, which is the sample surface, and the epi layer. _{The second reflected wave (reflectance R 23} ) reflected from the interface between the epi layer and the primary growth layer overlaps to form a total reflected wave (final reflectance R ₁₂₃ ). The third optical unit 510 collimates the terahertz wave (total reflected wave) reflected from the sample and transmits it to the fourth optical unit 520. The fourth optical unit 520 focuses the terahertz wave and guides it to the beam detector 530, and the beam detector 530 detects the terahertz wave, which is the total reflected wave. The beam detector 530 may include an A/D converter. The A/D converter may digitally convert the terahertz wave guided by the fourth optical unit 520 to generate a beam waveform.

Like the beam irradiation unit 300, the beam detection unit 500 may further include a second rail unit 540 in a bar shape. The beam detector 530, the third optical part 510, and the fourth optical part 520 are arranged in a line so that the optical axes coincide with each other on one surface of the second rail part 540, and the distance between them is adjusted. I can.

<Beam alignment unit 400>

The beam alignment unit 400 according to an embodiment of the present invention controls the bandwidth of the terahertz wave measured by the beam detector 530 to maximize the beam power. You can adjust the height.

The beam alignment unit 400 may include an angle adjustment unit 410 and a focusing adjustment unit 420.

The angle adjusting unit 410 may control the length and direction of a rotational trajectory in which the beam irradiating unit 300 moves so as to adjust the incident angle of the terahertz wave irradiated from the beam irradiating unit 300 to the object to be measured. The focusing adjustment unit 420 may adjust the height of the beam irradiation unit 300 so that the terahertz wave irradiated to the measurement object by the beam irradiation unit 300 is adjusted to be focused.

The angle adjusting part 410 includes a first vertical part 411, a first LM block 412, a second vertical part 414, a second LM block 415, a first round LM guiding part 416, A second round LM guiding unit 417 and a first guiding unit 418 may be included.

On the front surface of the first guiding portion 418, a first vertical extending downwardly perpendicular to the front surface of the first guiding portion 418 and fixed to the first rail portion 340 and the second rail portion 540 A portion 411 and a second vertical portion 414 may be included.

A first LM block 412 may be installed on one surface of the first vertical portion 411, and a second LM block 415 may be installed on one surface of the second vertical portion 414.

The first LM block 412 may be formed on the first side of the first guiding part 418. For example, referring to FIG. 6, the first LM block 412 may be formed on the left side of the first guiding part 418. The first LM block 412 has a ball insertion portion capable of including at least one ball on one surface thereof, and a ball is inserted into the ball insertion portion and guided by the first round LM guiding portion 416 Can be moved. Through the ball, it is possible to move along the first round LM guiding portion 416 while reducing friction with one surface of the first guiding portion 418.

The second LM block 415 may be formed on the second side of the first guiding part 418. For example, referring to FIG. 4, the second LM block 415 may be formed on the right side of the first guiding part 418. The second LM block 415 may be formed on the right side of the first guiding part 418. The second second LM block 415 has a ball insertion portion capable of including at least one ball on one surface thereof, a ball is inserted into the ball insertion portion, and a guide to the second round LM guiding portion 417 It can be loaded and moved. Through the ball, it is possible to move along the second round LM guiding portion 417 while reducing friction with one surface of the first guiding portion 418.

The first LM block 412 and the second LM block 415 move at the same speed while drawing a rotational trajectory having the same moving angle and the same arc length.

The first guiding unit 418 may guide the movement of the first LM block 412 and the second LM block 415.

6 and 9, the front of the first guiding portion 418 is a first hole 419h, a second hole 419i, a first round LM guiding portion 416, and a second round LM guiding portion. (417) may be included.

The first hole 419h, the second hole 419i, the first round LM guiding portion 416, and the second round LM guiding portion 417 have a round cross section. The first round LM guiding portion 416 and the second round LM guiding portion 417 are symmetrically left and right, and have the same length and radius of curvature of an arc. In addition, the first hole 419h and the second hole 419i have a round cross-section and have the same length and radius of curvature in a horizontal symmetrical manner.

For example, the first hole 419h may be formed on the left side of the first guiding part 418, and the second hole 419i may be formed on the right side of the first guiding part 418. Alternatively, the first hole 419h is formed on the right front side of the first guiding portion 418, and the second hole 419i is formed on the left front side of the first guiding portion 418.

The first round LM guiding portion 416 and the second round LM guiding portion 417 protrude perpendicularly to one surface of the first guiding portion 418 in an arc shape in cross section. The first round LM guiding portion 416 and the second round LM guiding portion 417 have the same radius of curvature and the same arc length. The first round LM guiding portion 416 may be formed on the left front side of the first guiding portion 418, and the second round LM guiding portion 417 may be formed on the right front side of the first guiding portion 418. . Alternatively, the first round LM guiding portion 416 is formed on the right front side of the first guiding portion 418, and the second round LM guiding portion 417 is formed on the left front side of the first guiding portion 418. I can.

The first round LM guiding portion 416 and the first hole 419h are formed in the same direction, and the second round LM guiding portion 417 and the second hole 419i are formed in the same direction. For example, the first round LM guiding part 416 and the first hole 419h are formed on the left front side of the guide part, and the second round LM guiding part 417 and the second hole 419i are formed on the right front side of the guide part. Can be.

The radius of curvature of the first round LM guiding part 416 is larger than the radius of curvature of the first hole 419h, and the radius of curvature of the second round LM guiding part 417 is also greater than the radius of curvature of the second hole 419i. .

The first LM block 412 of the present invention moves while drawing a rotational trajectory along the arc of the first round LM guiding part 416 on one surface of the first guiding part 418, and the second LM block 415 Is moved along a circular arc of the second round LM guiding part 417 while drawing a rotational trajectory on one surface of the first guiding part 418.

The movement time, movement direction, and movement angle of the first LM block 412 and the second LM block 415 are the same. Preferably, the moving angle may be 30° to 60° based on a center line of the first guiding part 418 or a screw part 419b to be described later. For example, if the first LM block 412 is moved 30° clockwise from the center line of the first guiding part 418 or the threaded part 419b, the second LM block 415 also moves the first guiding part 418 For the same time as one hour, the center line of the first guiding part 418 or the screw part 419b may be moved by 30° in the clockwise direction. As a result, the beam irradiation unit 300 and the beam detection unit 500 of the present invention may move while drawing the same rotational trajectory at the same moving angle for the same time period.

According to an embodiment of the present invention, the angle adjusting part 410 may further include a second guiding part 419 disposed on a rear surface (or upper surface) of the first guiding part 418. The rear surface (or upper surface) of the first guiding portion 418 and the front surface of the second guiding portion 419 are disposed to face each other.

The second guiding part 419 includes a rotating part 419a, a screw part 419b, a link base 419c, a first link arm 419d, a second link arm 419e, a first LM guide 419f, and a first LM guide 419f. 2 It may include an LM guide 419g, a first hole 419h, and a second hole 419i.

The rotating part 419a rotates clockwise or counterclockwise, and the screw part 419b is connected to the rotating part 419a, and converts the rotational motion of the rotating part 419a into a linear motion, thereby changing the link base 419c. Move it up and down. Preferably, the threaded portion 419b may be a ball screw.

The first ends of the first link arm 419d and the second link arm 419e are fixed to the link base 419c. The second end of the first link arm 419d may be fixed to the first LM block 412 or the first vertical portion 411. The second end of the second link arm 419e may be fixed to the second LM block 415 or the second vertical portion 414.

Preferably, the second end of the first link arm 419d may be fixed to the first LM block 412 or the first vertical portion 411 through the first hole 419h having a round cross section. . Similarly, the second end of the second link arm 419e may be fixed to the second LM block 415 or the second vertical portion 414 through the second hole 419i having a round cross section.

The link base 419c is guided by the first LM guide 419f and the second LM guide 419g, and may be raised and lowered.

When the link base 419c descends, the angle between the first link arm 419d and the second link arm 419e increases, so that the first LM block 412 or the first vertical portion 411 is counterclockwise. Then, the second LM block 415 or the second vertical portion 414 is moved in a clockwise direction. As a result, the beam irradiation unit 300 connected to the first vertical part 411 may move in a counterclockwise direction, and the beam detector connected to the second vertical part 414 may move in a clockwise direction.

Conversely, when the link base 419c rises, the angle between the first link arm 419d and the second link arm 419e decreases, so that the first LM block 412 or the first vertical portion 411 is clockwise. And the second LM block 415 or the second vertical portion 414 is moved in a counterclockwise direction. As a result, the beam irradiation unit connected to the first vertical part 411 may move in a clockwise direction, and the beam detector connected to the second vertical part 414 may move in a counterclockwise direction.

In this way, while the beam irradiation unit 300 moves while drawing a rotational trajectory, the incident angle of the terahertz wave emitted from the beam irradiation unit 300 is adjusted.

Meanwhile, the first LM block 412 or the first vertical part 411 and the second LM block 415 or the second vertical part 414 have different rotation directions, but the first LM block 412 or the first vertical part 414 The moving angle and the length of the arc of the rotation trajectory in which the part 411 and the second LM block 415 or the second vertical part 414 move are the same. Accordingly, the moving angle and the length of the arc of the beam irradiation unit 300 (and the rotational trajectory 500 on which the beam detection unit moves) are the same.

According to an embodiment of the present invention, the focusing control unit 420 is connected to the rear surface of the second guiding unit 419 and may move the second guiding unit 419 up and down. When the second guiding unit 419 moves up and down, the beam irradiation unit 300 and the beam detection unit 500 connected to the second guiding unit 419 also move up and down along the first guiding unit 418.

An LM block (not shown) is installed on a rear surface of the second guiding part 419, and a ball insertion part into which a ball can be inserted is installed in the LM block. The front surface of the focusing adjustment unit 420 faces the rear surface of the second guiding unit 419. The front surface of the focusing control unit 420 may include an LM guide unit for guiding an LM block, disposed parallel to the LM guide unit, and an LM block moving unit that moves the LM block up and down.

A first sensing unit for detecting the movement of the first LM block 412 is installed on one surface of the first LM block 412 to transmit the moving angle of the first vertical part to the beam controller 600 to be described later. The first sensing unit may include a plurality of motion detection sensors disposed at a predetermined angle, and may detect a moving angle of the first vertical portion 411a and transmit it to the beam controller 600.

In addition, a camera that senses the height of the beam irradiation unit 300 is disposed inside the measurement system to detect the height of the beam irradiation unit 300 and transmit it to a beam controller to be described later.

<Beam control unit 600>

The beam controller 600 according to an embodiment of the present invention may include a beam receiving unit 610, a beam analyzing unit 620, and a beam control signal generating unit 630.

When the first vertical portion 411 moves while drawing a predetermined rotational trajectory, the beam irradiation unit 300 also moves while drawing a rotational trajectory and adjusts the incident angle of the terahertz wave with respect to the measurement object.

When the second guiding part 419 rises, the first guiding part 418 connected to the first guiding part 419 also rises, and the beam irradiation part 300 fixed to the first guiding part 418 It rises along the first guiding part 418 and adjusts the terahertz wave focusing on the measurement object.

The beam receiver 610 receives the half-wave terahertz wave waveform from the A/D converter and transmits it to the beam analyzer 620.

The beam analysis unit 620 receives the movement angle of the first LM block 412 from the first sensor unit and the height of the beam irradiation unit 300 from the second sensor unit, and receives terra from the beam receiving unit 610. It receives the waveform of the Hertz wave.

The beam analysis unit 620 processes the received terahertz waveform in the time domain and converts it into a frequency domain, and the moving angle of the first LM block 412 at which the bandwidth of the waveform is minimum and The height of the beam irradiation unit 300 may be determined. The determined movement angle of the first LM block 412 and height information of the beam irradiation unit 300 may be transmitted to the beam control signal generation unit 630.

Alternatively, the beam analyzer 620 analyzes the waveform of the terahertz wave converted to the frequency domain, and when the waveform of the terahertz wave falls below a predetermined bandwidth, the first LM block 412 corresponding thereto The moving angle of and the height information of the beam irradiation unit 300 may be transmitted to the beam control signal generation unit 630.

The beam control signal generation unit 630 controls the movement angle of the rotational trajectory in which the first LM block 412 moves so as to correspond to the movement angle of the first LM block 412 received from the beam analysis unit 620 It is possible to generate a first control signal. In addition, a second control signal for controlling a vertical movement distance of the first guiding unit 418 may be generated to correspond to the height of the beam irradiating unit 300 received from the beam analyzing unit 620.

The first LM block 412 moves while drawing a rotational trajectory having a moving angle according to a first control signal, and the LM block of the focusing control unit moves so that the beam irradiation unit 300 corresponds to the height according to the second control signal. I can.

<Sukjeongban (900)>

The measurement system according to an embodiment of the present invention may include a fixing part that fixes the rear surface of the focusing control part 420 and a stage capable of mounting and transferring the measurement object. The fixing part 700 and the stage By arranging 800 on the upper surface of the stone table 900, vibration can be minimized when measuring the thickness of the object to be measured and other physical properties.

<Chamber (1000)>

In addition, the measurement system according to an embodiment of the present invention may further include a chamber 1000. The beam irradiation unit 300, the beam detection unit 500, the beam alignment unit 400, the measurement object (wafer), the fixing unit 700, and the stage 800 are sealed through the chamber 1000 can do. An air supply unit 1300 driving to supply dry air into the chamber 1000 may be disposed outside the chamber 1000.

The chamber 1000 may include an air injection unit and an air discharge unit. The air injection unit may be connected to the air supply unit 1300 to receive dry air from the air supply unit 1300. The air discharge unit may discharge air inside the chamber 1000 to the outside. When external dry air is supplied into the chamber 1000, circulation occurs inside the chamber 1000, and the internal air is discharged to the outside through the air discharge unit.

In addition, the measurement system may further include a humidity sensor (not shown) and a humidity control unit 1200. The humidity sensor 1100 is disposed inside the chamber 1000, detects humidity in the chamber 1000, and transmits the detected humidity information to the humidity control unit 1200. The humidity control unit 1200 generates a control signal for controlling the amount of dry air injected into the air injection unit so that the humidity inside the chamber 1000 is within a predetermined range based on the received humidity information, and the air supply unit It is transmitted to a valve connected to 1300, and on/off of the valve may be controlled. Alternatively, driving of the air supply unit 1300 may be controlled by transmitting the control signal to the air supply unit 1300.

Preferably, the humidity control unit may control the driving of the air supply unit 1300 or on/off of the valve so that the humidity inside the chamber 1000 is 5% or less.

14 is a waveform of a reflected wave detected before humidity control, and FIG. 15 is a waveform of a reflected wave detected after humidity control. Referring to FIGS. 14 and 15, it can be seen that the frequency signal of the reflected wave is improved after the humidity control.

Claims (9)

A beam generator 100 for generating a pulsed wave type beam;
A beam splitter 200 for dividing the pulsed beam into a first femtosecond pulse 210 and a second femtosecond pulse 220;
A beam irradiation unit 300 receiving the first femtosecond pulse 210 divided by the beam splitting unit 200, converting it to a terahertz wave, and irradiating it to a measurement object;
The terahertz wave irradiated by the beam irradiation unit 300 is reflected by the measurement object, and a beam detector receiving the terahertz wave reflected by the measurement object and the second femtosecond pulse 220 divided by the beam splitting unit 200 (500); And
Measurement system comprising a beam alignment unit 400 for controlling the bandwidth of the reflected terahertz wave by adjusting the rotation angle and height of the beam irradiation unit 300. The method of claim 1,
The beam irradiation unit 300 is a terahertz emitter 310 that receives the first femtosecond pulse 210 and converts it to a terahertz wave and emits it, and collimates the terahertz wave emitted from the terahertz emitter 310. Including a first optical unit 320, a second optical unit 330 that focuses the terahertz wave collimated by the first optical unit 320,
The beam detection unit 500 includes a third optical unit 510 for collimating the terahertz wave reflected from the object to be measured, and a fourth optical unit for focusing the terahertz wave collimated by the third optical unit 510 Including a beam detector 530 for detecting the terahertz wave focused by the unit 520 and the fourth optical unit 520 and the second femtosecond pulse 220 divided by the beam splitting unit 200,
The beam irradiation unit 300 includes a first rail unit 340 capable of adjusting the arrangement of the terahertz emitter 310, the first optical unit 320, and the second optical unit 330,
The beam detection unit 500 includes a second rail unit 540 capable of adjusting the arrangement of the third optical unit 510, the fourth optical unit 520, and the beam detector 530. Measuring system. The method of claim 1,
The beam alignment unit 400 includes an angle adjustment unit 410 for adjusting the incident angle of the terahertz wave irradiated by the beam irradiation unit 300. The method of claim 1,
The beam alignment unit 400 further comprises a focusing adjustment unit 420 for adjusting the focusing of the terahertz wave irradiated by the beam irradiation unit 300. The method of claim 4, wherein the angle adjustment unit 410
A first vertical part 411, a first LM block 412, a second vertical part 414, a second LM block 415, a first round LM guiding part 416, a second round LM guiding part 417 ), including a first guiding part 418,
The first round LM guiding portion 416 and the second round LM guiding portion 417 protrude from the first surface of the first guiding portion 418 in a first radius of curvature,
The first round LM guiding part 416 is formed in a direction opposite to the second round LM guiding part 417,
The first round LM guiding unit 416 guides the first LM block 412 to move while drawing a rotational trajectory along an arc on one surface of the first guiding unit 418, and
The second round LM guiding part 417 guides the second LM block 415 to move while drawing a rotational trajectory along an arc on one surface of the first guiding part 418,
One surface of the first LM block 412 and the second LM block 415 is provided with the first round LM guiding part 416 and the second, respectively, while reducing friction with one surface of the first guiding part 418. Measurement system, characterized in that it comprises at least one ball (ball) movable along the round LM guiding portion (417). The method of claim 5,
The angle adjusting part 410 further includes a second guiding part 419 disposed on the second surface of the first guiding part 418,
The second surface of the first guiding part 418 and the first surface of the second guiding part 419 face each other,
The second guiding part 419 includes a link base 419c, a first LM guide 419f, and a second LM guide 419g,
The link base (419c) is guided to the first LM guide (419f) and the second LM guide (419g) and is raised and lowered,
As the link base 419c is raised or lowered, the beam irradiation unit 300 moves in a first clockwise direction, and the beam detector moves in a second clockwise direction, but the beam irradiation unit 300 and the beam detection unit ( Measurement system, characterized in that the moving angle of the rotational trajectory in which 500) moves and the length of the arc are identical. The method of claim 6,
The focusing control unit 420 is disposed on the second surface of the second guiding unit 419 and is connected to a part of the second surface of the second guiding unit 420 to adjust the height of the second guiding unit Measurement system, characterized in that. The method of claim 7, wherein the measurement system further comprises a beam control unit (600),
The beam detector 530 transmits the terahertz wave reflected from the measurement object to the beam controller 600, and the beam controller 600 converts the reflected terahertz wave into a frequency domain, and the And generating a control signal for controlling a rotational trajectory of the first LM block 412 and a vertical movement distance of the second guiding unit so that a bandwidth of the converted terahertz wave is minimized. The method of claim 1,
The measurement system is
Further comprising a fixing portion 700 for fixing the second surface of the focusing adjustment portion 420 and a stage 800 capable of mounting and transferring the measurement object,
The fixing part 700 and the stage 800 are disposed on the upper surface of the seokjeongban 700,
The beam irradiation unit 300, the beam detection unit 500, the beam alignment unit 400, the measurement object, the fixing unit 700, and the stage 800 disposed on the stone table 700 are sealed. Including a chamber 1000 to form a space,
The chamber 1000 includes an air injection unit and an air discharge unit,
The air injection unit is connected to an air supply unit 1300 driving to supply dry air into the chamber 1000-the air supply unit 1300 is disposed outside the chamber 1000,
Measurement system, characterized in that the air discharge unit discharges the air inside the chamber (1000) to the outside.

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