WO2019027268A1 - Piezoelectric material column and manufacturing method therefor - Google Patents

Piezoelectric material column and manufacturing method therefor Download PDF

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Publication number
WO2019027268A1
WO2019027268A1 PCT/KR2018/008779 KR2018008779W WO2019027268A1 WO 2019027268 A1 WO2019027268 A1 WO 2019027268A1 KR 2018008779 W KR2018008779 W KR 2018008779W WO 2019027268 A1 WO2019027268 A1 WO 2019027268A1
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piezoelectric material
mold
filling
sintering
column
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PCT/KR2018/008779
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French (fr)
Korean (ko)
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김경국
김시원
노범래
조지연
최희정
추은경
안범모
박승호
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㈜포인트엔지니어링
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Publication of WO2019027268A1 publication Critical patent/WO2019027268A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/50—Assembly of semiconductor devices using processes or apparatus not provided for in a single one of the subgroups H01L21/06 - H01L21/326, e.g. sealing of a cap to a base of a container
    • H01L21/56—Encapsulations, e.g. encapsulation layers, coatings
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/01—Manufacture or treatment
    • H10N30/08—Shaping or machining of piezoelectric or electrostrictive bodies
    • H10N30/084—Shaping or machining of piezoelectric or electrostrictive bodies by moulding or extrusion
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/01—Manufacture or treatment
    • H10N30/09—Forming piezoelectric or electrostrictive materials
    • H10N30/093—Forming inorganic materials
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/01—Manufacture or treatment
    • H10N30/09—Forming piezoelectric or electrostrictive materials
    • H10N30/093—Forming inorganic materials
    • H10N30/097—Forming inorganic materials by sintering
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/85—Piezoelectric or electrostrictive active materials
    • H10N30/853—Ceramic compositions

Definitions

  • the present invention relates to a piezoelectric material column and a manufacturing method thereof, and more particularly, to a piezoelectric material column as a core material of an ultrasonic fingerprint sensor and a manufacturing method thereof.
  • the structure For ultrasound fingerprint recognition, the structure must be made using a material called titanate zirconate titanate (PZT, lead zirconate titanate). These materials are known as piezoelectric materials and have the characteristic of converting mechanical forces into electrical signals. Therefore, if mechanical force is applied to the nano-structured PZT structure, the fingerprint is recognized at the moment of applying force. Since the ultrasonic fingerprint sensor using PZT is measured in three dimensions, it has characteristics that fingerprint duplication is not performed.
  • PZT titanate zirconate titanate
  • the present fingerprint recognition method has a limitation in security because it can read fingerprints of other people's fingerprints using a tape or the like in a two-dimensionally read pattern only manner.
  • MEMS Ultrasonic Fibers
  • a rectangular cross-section or a round shape it has a nano-rod structure of a rectangular pillar or a cylindrical shape having a side or a size of several tens of ⁇ m and a height of 100 ⁇ m or more.
  • a PZT material should be molded into a square or columnar mold and then sintered to form a dense PZT nanostructure.
  • the PZT material must be filled in molds with a width and height of several ⁇ m to several tens of ⁇ m and a height of several tens of ⁇ m to several hundred ⁇ m. Especially filling is the most important technique to fill the mold with uniform density.
  • the most popular technique is to use a green sheet called PZT to stack the wafer bonder with the mold, and then apply pressure to the press.
  • PZT a green sheet
  • the air inside the wafer bonder is removed with a vacuum pump to prevent the air inside the mold from interfering with the filling in the PZT filling process, and then the PZT is charged into the mold by applying pressure to the green sheet.
  • the PZT nanostructure must be sintered while maintaining the initial shape in the sintering process.
  • the rectangular PZT nanostructured forms The problem of collapsing occurs.
  • interfacial reaction occurs between the semiconductor wafer such as Si and the PZT material, resulting in a problem of collapse of the mold shape.
  • the fundamental reason for this is that the PZT sintering is performed at a temperature of 800 ° C or more for a long period of time of three to four hours or longer because the PZT sintering takes place by the reduction of the grain boundary area between the PZT grains.
  • the interfacial reaction with the semiconductor mold also occurs through the same reaction process. Therefore, the problem of the PZT sintering process is generally that the higher the temperature, the longer the reaction time is. Therefore, controlling the problems of the conventional sintering reaction is a key technology for making stable PZT nanostructures, and many research groups have attempted to solve the problem. In particular, a method of controlling the composition of PZT and sintering at low temperature has been proposed. However, in case of PZT low-temperature sintering, the physical properties after sintering may change.
  • the present invention minimizes shrinkage during sintering of a piezoelectric material column (a polygonal column and a circular column such as a quadrangular column), thereby maintaining the initial column structure, and at the same time suppressing the interfacial reaction with the mold, And the like.
  • the piezoelectric material column according to the present invention is characterized in that the sintered density at one end of the sintered piezoelectric material column is higher than the sintered density at the other end.
  • the piezoelectric material column is characterized in that it is composed of only a piezoelectric material without detecting a binder compound.
  • the piezoelectric material is PZT.
  • a method of manufacturing a piezoelectric material column comprising: preparing a mold having a plurality of filling holes; A filling step of filling particles of the piezoelectric material from the bottom surface of the filling hole of the mold with a high-pressure gas injection pressure; And a sintering step of subjecting the piezoelectric material filled in the filling hole of the mold to rapid thermal annealing and sintering.
  • the particles of the piezoelectric material are mixed with particles having different particle diameters.
  • the gas injection pressure is in the range of 1 atm to 4 atm.
  • the rapid thermal annealing time is 1 minute to 5 minutes, and the rapid thermal annealing temperature is 700 ° C to 1100 ° C.
  • the piezoelectric material column and the manufacturing method thereof according to the present invention minimize the shrinkage occurring in the process of sintering piezoelectric material columns (polygonal columns and circular columns such as square columns) At the same time, the interfacial reaction with the mold is suppressed, and a stable piezoelectric material column can be realized.
  • Fig. 2 is a photograph of a piezoelectric material column manufactured by the conventional technique of the present invention.
  • FIG. 3 is a view showing an apparatus for jetting piezoelectric material particles according to a preferred embodiment of the present invention.
  • FIG. 4 is a view showing a state before a piezoelectric material particle is filled in a filling hole of a mold according to a preferred embodiment of the present invention.
  • FIG. 5 is a view showing a piezoelectric material column manufactured by sintering a piezoelectric material filled in a filling hole according to a preferred embodiment of the present invention.
  • FIG. 6 is a view showing a state where a piezoelectric material is filled in a filling hole of a mold according to a preferred embodiment of the present invention.
  • FIG. 7 is a view showing a boundary surface (a portion that is sintered and a portion that is torn out) in accordance with a preferred embodiment of the present invention.
  • FIG 8 and 9 are views showing a piezoelectric material column after a rapid heat treatment of a piezoelectric material filled in a filling hole according to a preferred embodiment of the present invention.
  • a semiconductor substrate such as a Si wafer is used as a mold.
  • a piezoelectric material-based fingerprint sensor is manufactured by such a mold method, a semiconductor wafer is etched to form a mold, and a piezoelectric material It is necessary to fill the nano structure (a polygonal nano structure such as a quadrangular column and a circular or elliptic column).
  • the initial piezoelectric material should be filled in the semiconductor mold, and after the filling, the piezoelectric material should be sintered through a heat treatment process.
  • the sintered piezoelectric material nanostructure can be used as a structure required for an ultrasonic fingerprint sensor.
  • piezoelectric material nanostructures can be operated as an ultrasonic fingerprint sensor in a variety of shapes and shapes ranging from a few um to a few hundred um, but with a constant periodicity. Therefore, it is a key technology to fabricate a nanostructure with a period of various sizes ranging from nm to um.
  • the reason why the periodicity is collapsed during the sintering process of the piezoelectric material nanostructure is that the piezoelectric material shrinks during the first sintering process. This is a natural course of the piezoelectric material sintering principle.
  • piezoelectric materials used in general use a variety of binders in addition to piezoelectric materials, more shrinkage occurs in the binder volume during the sintering process.
  • the second piezoelectric material nanostructure sintering problem necessarily occurs during the long sintering process at the sintering temperature of 800 ° C or higher in the case of the interfacial reaction. These high-temperature sintering reactions also directly cause sintering shrinkage of the piezoelectric material. Therefore, in the present invention, a rapid thermal annealing process is applied in the aspect of reaction kinetics to propose a method that can reduce the interfacial reaction and reduce the shrinkage in an innovative manner.
  • the method of manufacturing a piezoelectric material column minimizes shrinkage generated in the process of sintering a piezoelectric material column (a polygonal column and a circular column such as a quadrangular column), thereby maintaining the initial column structure,
  • the piezoelectric material of the particle state is filled in the filling hole of the mold by using the high-pressure gas injection pressure without using a binder in order to realize a stable piezoelectric material column by suppressing the interfacial reaction of the piezoelectric material.
  • the overall fluidity can be improved, but it has various problems.
  • the size of the piezoelectric material particle actually increases, so that the bonding force between the particles increases.
  • the sintering process shrinks by the coating volume surrounding the outer portion, (See Fig. 2).
  • the binder which has not yet been removed from the bottom of the filling hole, is burned at a high temperature and remains in the form of a binder compound, which deteriorates the piezoelectric function.
  • the use of a binder is negatively recognized, and only a piezoelectric material in a particle state is filled in a filling hole of a mold.
  • no binder is used in the production of piezoelectric columns.
  • the leakage problem and the porosity problem in the filling hole of the piezoelectric material should be solved. That is, in filling the filling hole of the mold with the piezoelectric material composed only of the powder type particles, the piezoelectric material particles previously filled in the filling hole should not be leaked out by the piezoelectric material particles to be filled later. Also, if air remains around the pre-filled piezoelectric particles, it is necessary to solve the problem that the shrinkage rate increases greatly during the sintering process even if the piezoelectric material particles are not properly filled or filled by the remaining air pressure.
  • a configuration is adopted in which the particles of the piezoelectric material are filled in the filling holes of the mold with a high-pressure gas injection pressure.
  • the particles of the piezoelectric material introduced into the filling hole by the high-pressure gas injection pressure are stacked and laminated on the surface of the piezoelectric material filled in advance,
  • the shrinkage rate can be minimized by using the piezoelectric material particles having different particle diameters in order to reduce the porosity between the piezoelectric material particles.
  • a method of filling a piezoelectric material into a filling hole by using a shape of a green sheet or a slurry is a top-down method in which a piezoelectric material is pushed down into a top portion of a filling hole. Up method in which the piezoelectric material particles are filled from the lower part to the upper part of the filling hole.
  • the preferred embodiment of the present invention is characterized in that the piezoelectric material filled in the filling hole is subjected to rapid thermal annealing so that the sintered density on the column surface is higher than that of the inside so that the piezoelectric material column can maintain the shape of the filling hole. In this way, the shrinkage of each of the pillars of the piezoelectric material is minimized, so that each of the plurality of piezoelectric material pillars has the same geometrical shape, thereby exhibiting the same piezoelectric characteristics.
  • a method of manufacturing a piezoelectric material column includes: preparing a mold 400 having a plurality of filling holes 410; A filling step of filling the piezoelectric material particles 500 from the bottom surface of the filling hole 410 of the mold 400 with a high-pressure gas injection pressure; And a sintering step of subjecting the piezoelectric material filled in the filling hole 410 of the mold 400 to rapid thermal annealing and sintering.
  • the filling hole 410 may have a circular or polygonal cross-sectional shape, but is not limited thereto.
  • the injection nozzle 300 is connected to the injection pressure generator 100, and the injection pressure generator 100 generates a high-pressure gas pressure.
  • the gas injection pressure is lower than the lower limit of the predetermined range, the piezoelectric material particles are not properly stacked in the filling hole 410 because of their weak bonding force with other piezoelectric material particles.
  • the gas injection pressure is higher than the upper limit value of the predetermined range
  • the side wall of the filling hole 410 may be damaged by the gas injection pressure. Therefore, it is preferable that the gas injection pressure is limited within a predetermined range.
  • the gas injection pressure preferably ranges from 1 atm to 50 atm. Such gas injection pressure enables stable filling of the piezoelectric material particles and minimizes porosity.
  • the particle storage unit 200 stores the piezoelectric material in the form of particles.
  • the piezoelectric material may be lead titanate zirconate titanate (PZT, lead zirconate titanate).
  • PZT lead titanate zirconate titanate
  • the present invention is not limited thereto. If the size of the piezoelectric material particles 500 is larger than the upper limit of the predetermined range, the porosity increases and the shrinkage rate increases. If the size is smaller than the lower limit of the predetermined range, the filling efficiency is lowered. According to a preferred embodiment of the present invention, the size of the piezoelectric material particles 500 preferably has a particle size of several tens nm or more and 5 ⁇ m or less, more preferably 1 ⁇ m or less.
  • the particle storage part 200 may be provided by mixing piezoelectric material particles 500 having different particle diameters.
  • the piezoelectric material particles stored in the particle storage unit 200 are mixed with the high-pressure gas pressure generated in the injection-pressure generating unit 100 and are discharged through the injection nozzle 300.
  • the injection nozzle 300 injects the piezoelectric material particles 500 having different particle diameters toward the mold 400 side. Since the particle diameters of the piezoelectric material particles 500 are different from each other, the porosity of the piezoelectric material particles 500 filled in the filling hole 410 can be reduced, and the shrinkage rate during sintering can be minimized.
  • the piezoelectric material particles 500 discharged through the injection nozzle 300 are introduced into the filling holes 410 of the mold 400 and stacked.
  • the piezoelectric material particles 500 continuously flowing into the filling hole 410 are filled with the piezoelectric material Particles 500 are combined with each other.
  • the filling speed of the piezoelectric material particles 500 is 20 mu m / sec or more.
  • the piezoelectric material particles 500 are stacked while being bonded to the surface of the piezoelectric material particles 500 filled in advance, the piezoelectric material particles 500 have an effect of aggregating the piezoelectric material particles 500, thereby preventing leakage of the particles of the previously filled piezoelectric material do.
  • the piezoelectric material particles 500 have different particle diameters, the porosity of the piezoelectric material particles 500 when they are laminated can be reduced.
  • the piezoelectric material particles 500 having a relatively small particle size can pass through between the piezoelectric material particles 500 having a relatively large particle size filled by the gas pressure of a high pressure and move downwardly, thereby effectively reducing the porosity .
  • the porosity is effectively reduced, so that the shrinkage rate during sintering can be minimized (see FIG. 6).
  • the piezoelectric material filled in the filling hole 410 is heat-treated to produce the piezoelectric material column 600.
  • the sintered piezoelectric material column 600 can not maintain the shape of the filling hole 410 of the mold 400 and can not function properly as the piezoelectric material column 600.
  • the sintered density on the surface of the sintered piezoelectric material column 600 is higher than the inner sintered density so that the piezoelectric material column 600 can maintain the shape of the filling hole 410 will be.
  • FIG. 7 is a view of a boundary surface (a part sintered and a part torn off) to check the difference in sintered density between the surface of the piezoelectric material column 600 and the inside thereof. Referring to FIG. 7, it can be seen that the sintered density at the surface (A) of the piezoelectric material column (600) is high and the sintered density of the inside (B) is relatively low.
  • the rapid sintering of the surface (A) of the piezoelectric material column 600 minimizes the volume reduction of the piezoelectric material column 600.
  • the piezoelectric material column 600 is used for an ultrasonic fingerprint sensor, electrodes are formed at both ends of the piezoelectric material column 600, and the surface A and the inside B can be reversed up and down.
  • the sintered density at the end portion becomes higher than the sintered density at the other end portion.
  • the piezoelectric material column has a configuration in which the sintered density at one end of the sintered piezoelectric material column is higher than the sintered density at the other end.
  • the piezoelectric material column 600 is manufactured using only the piezoelectric material particles 500 without adopting a binder, a binder compound is not detected in the piezoelectric material column 600. [ Therefore, when the piezoelectric material column according to the preferred embodiment of the present invention is employed in the ultrasonic fingerprint sensor, the performance of the ultrasonic fingerprint sensor can be improved (see FIGS. 8 and 9).
  • the preferred embodiment of the present invention performs a rapid thermal annealing process for sintering the piezoelectric material filled in the filling hole 410 of the mold 400.
  • the rapid thermal annealing time is preferably from 1 minute to 5 minutes, and the rapid thermal annealing temperature is preferably 700 ° C to 1100 ° C.
  • the gas atmosphere be at atmospheric pressure. Since the heater for rapid thermal annealing is separately provided outside, the heater and the mold are not in direct contact with each other. In order to increase the sintering density at the surface of the piezoelectric material column 600 by operating the heater, the atmosphere should be such that the gas atmosphere can sufficiently conduct convection of heat. If the gas atmosphere is at atmospheric pressure, the convection of the heat is sufficiently performed, so that rapid heat treatment on the surface of the piezoelectric material column 600 as desired in the preferred embodiment of the present invention becomes possible.
  • the surface and the interior have similar sintered densities and the whole three-dimensional shrinkage occurs.
  • Time is not given. Therefore, the shrinkage of the piezoelectric material structure after heat treatment is minimized, and the interfacial reaction is also hardly occurred due to the short reaction time. Furthermore, since the binder is not used, the reaction at the interface is suppressed and stable piezoelectric material structure sintering is possible.
  • the shrinkage due to the sintering reaction of the piezoelectric material can be minimized to 2 ⁇ m or less in the case of the square shape of the piezoelectric material having the size of about 50 ⁇ m ⁇ 50 ⁇ m ⁇ 180 ⁇ m.
  • it is very good in mass productivity, so that a large amount of piezoelectric material can be sintered for a predetermined time, and the reproducibility is also excellent.

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Abstract

The present invention relates to: a piezoelectric material column characterized in that the sintering density at one end portion of a sintered piezoelectric material column is higher than the sintering density at the other end portion thereof; and a piezoelectric material column manufacturing method comprising a mold preparation step of preparing a mold having a plurality of filling holes, a filling step of filling, by means of high gas spray pressure, the filling holes of the mold from the bottom surfaces thereof with particles of a piezoelectric material, and a sintering step of quickly and thermally treating the piezoelectric material filled in the filling holes of the mold and sintering the same.

Description

압전 소재 기둥 및 그 제조방법Piezoelectric material column and its manufacturing method
본 발명은 압전 소재 기둥 및 그 제조방법에 관한 것으로서, 더욱 상세하게는 초음파 지문센서의 핵심 소재인 압전 소재 기둥 및 그 제조방법에 관한 것이다.The present invention relates to a piezoelectric material column and a manufacturing method thereof, and more particularly, to a piezoelectric material column as a core material of an ultrasonic fingerprint sensor and a manufacturing method thereof.
보안에 대한 중요성이 강조되면서 다양한 보안 방법이 제시되고 있다. 그 중에서 지문인식 방식은 본인을 확인할 수 있는 가장 효과적인 방법 중의 하나이기 때문에 많은 분야에서 채용하고 있다. As the importance of security is emphasized, various security methods are being suggested. Among them, fingerprint recognition is one of the most effective ways to identify you, so it is adopted in many fields.
그러나 지문을 인식하는 방식은 여러 가지가 있으며 현재까지 휴대폰에서 사용하고 있는 정전방식이 가장 일반적으로 사용하고 있으나 이러한 방식은 지문을 복사해서 사용할 수 있는 단점을 가지고 있다. 따라서 기존의 지문인식방식이 아닌 복사가 불가능한 새로운 방법의 지문 인식 방식의 필요성이 증가하고 있으며 이에 제시되고 있는 방식이 초음파지문인식 방식이다. However, there are many ways to recognize fingerprints, and the most common method of using static electricity in mobile phones is to use fingerprints. Therefore, there is an increasing need for a new fingerprint recognition method that is not a conventional fingerprint recognition method, and an ultrasonic fingerprint recognition method is proposed.
초음파 지문인식을 하기 위해서는 티탄산 지르콘산 연(타이타늄산 지르콘산 연) [PZT, lead zirconate titanate ]이라는 소재를 사용해서 구조를 제작해야 한다. 이러한 물질은 흔희 압전 소재로 알려져 있는 물질로 기계적인 힘을 전기적인 신호로 바꾸어주는 역할을 하는 특징을 가지고 있다. 따라서 나노급으로 구성된 PZT구조에 3차원적 지문 행태가 기계적인 힘이 가해진다면 힘을 가하는 순간에 지문을 인식하게 된다. 이러한 PZT를 이용한 초음파 지문센서는 3차원으로 측정되기 때문에 지문복제가 되지 않은 특징을 가지고 있다. For ultrasound fingerprint recognition, the structure must be made using a material called titanate zirconate titanate (PZT, lead zirconate titanate). These materials are known as piezoelectric materials and have the characteristic of converting mechanical forces into electrical signals. Therefore, if mechanical force is applied to the nano-structured PZT structure, the fingerprint is recognized at the moment of applying force. Since the ultrasonic fingerprint sensor using PZT is measured in three dimensions, it has characteristics that fingerprint duplication is not performed.
이에 비해서 현재의 지문 인식방식은 2차원적으로 무늬만을 읽는 방식으로 타인의 지문을 테이프 등을 이용해서 지문 복사가 가능하기 때문에 보안에 한계가 있다. On the other hand, the present fingerprint recognition method has a limitation in security because it can read fingerprints of other people's fingerprints using a tape or the like in a two-dimensionally read pattern only manner.
현재 초음파지문인식 센서를 위해서는 멤스(MEMS)공정을 적용해야 한다. 특히 사각형의 단면 또는 원형인 경우 한 변이나 지금의 크기나 가 수십 um이며, 높이가 100um이상인 사각 기둥이나 원기둥 형태의 나노로드 구조를 가지고 있다. Currently, MEMS (Ultrasonic Fibers) process must be applied to ultrasonic fingerprint sensors. Particularly, in the case of a rectangular cross-section or a round shape, it has a nano-rod structure of a rectangular pillar or a cylindrical shape having a side or a size of several tens of μm and a height of 100 μm or more.
따라서 압전 소재를 사각기둥 또는 원기둥 형태의 나노구조로 제작하기 위한 다양한 기술이 개발되고 있다. 그러나 현재까지 이러한 나노구조로 제작하기 위해서는 PZT소재를 사각기둥 또는 원기둥 형태로 일정한 틀(mold)에 넣어서 성형하고 이후 소결을 통해서 밀도가 높은 PZT나노구조를 제작 해야한다. 그러나 이 과정에서 PZT 소재를 가로, 세로 길이가 수um ~ 수십 um, 높이가 수십 um ~ 수백 um인 몰드에 충진해야 한다. 특히 충진은 균일한 밀도를 가지면서 성형 되도록 충진하는 것이 가장 핵심적인 기술이다.Therefore, various techniques are being developed to fabricate piezoelectric materials in a square pillar or cylindrical shape. However, in order to fabricate such a nanostructure, a PZT material should be molded into a square or columnar mold and then sintered to form a dense PZT nanostructure. In this process, however, the PZT material must be filled in molds with a width and height of several μm to several tens of μm and a height of several tens of μm to several hundred μm. Especially filling is the most important technique to fill the mold with uniform density.
현재 가장 많이 사용하는 기술은 green sheet라는 PZT 소재를 사용하여 wafer bonder에 몰드와 함께 겹겹이 쌓은 다음 프레스로 압력을 가하는 방식이다. 이 경우 PZT충진 과정에서 몰드 내부의 공기가 충진을 방해하는 것을 억제하기 위해서 진공펌프로 wafer bonder 내부의 공기를 제거하고 난 후에 Green sheet에 압력을 가해 몰드 내부로 PZT를 장입한다. Currently, the most popular technique is to use a green sheet called PZT to stack the wafer bonder with the mold, and then apply pressure to the press. In this case, the air inside the wafer bonder is removed with a vacuum pump to prevent the air inside the mold from interfering with the filling in the PZT filling process, and then the PZT is charged into the mold by applying pressure to the green sheet.
그러나 이러한 방식으로도 현재까지 100um 이상의 높이를 갖는 몰드에 PZT를 안정적인 장입은 이루어지지 않고 있다. 도 1를 참조하면 충진홀(11)이 구비된 몰드(10)상에서 바(20)를 이용하여 PZT 슬러리(slurry, 30)를 전체적으로 도포하는 과정을 수회 반복 수행하고, 더미 웨이퍼(30)로 가압하여 PZT 슬러리(slurry, 30)를 충진홀 내부로 충진하게 된다. 그러나 Green sheet 또는 Green sheet가 소재인 PZT slurry(30)의 경우 바인더(binder)를 사용하기 때문에 표면장력이 작용하여 상부에서 가압하는 더미 웨이퍼(30)의 힘이 제거되면 수축되는 현상이 발생하여 몰드(10)의 충진홀(11)에 장입을 하거나 장입 후 형태 유지에 한계가 있는 문제점이 있다.However, in this way, the stable charging of PZT into a mold having a height of 100um or more has not been achieved so far. Referring to FIG. 1, a process of applying a PZT slurry 30 as a whole onto a mold 10 having a filling hole 11 is repeated several times using a bar 20, And the PZT slurry 30 is filled into the filling hole. However, in the case of the PZT slurry 30 in which the green sheet or the green sheet is the base material, since the binder is used, surface tension acts to shrink when the force of the dummy wafer 30 pressurized at the upper portion is removed, There is a problem in that it is charged into the filling hole 11 of the container 10 or there is a limit to the shape maintenance after charging.
한편, 도 2에 도시된 바와 같이 소결 과정에서 PZT 나노구조가 초기 형태를 유지하면서 소결되어야 하지만 소결 과정에서 수축이 발생하는 문제점으로 인해서 초기 PZT 나노구조 형태인 사각 기둥이나 원형 기둥이 형태를 유지하지 못하고 무너지는 문제가 발생한다. 더욱이 Si몰드 등 반도체 웨이퍼를 사용한 몰드 기반 PZT 소결의 경우 Si 등 반도체 웨이퍼와 PZT 물질간 계면 반응이 일어나서 몰드의 형태가 무너지는 문제가 또한 발생한다. Meanwhile, as shown in FIG. 2, the PZT nanostructure must be sintered while maintaining the initial shape in the sintering process. However, due to the problem of shrinkage during the sintering process, the rectangular PZT nanostructured forms The problem of collapsing occurs. Furthermore, in the case of mold-based PZT sintering using a semiconductor wafer such as Si mold, interfacial reaction occurs between the semiconductor wafer such as Si and the PZT material, resulting in a problem of collapse of the mold shape.
이러한 근본적인 이유는 PZT 소결은 PZT입자 사이의 결정립 경계 (grain boundary) 면적 감소를 구동력으로 하여 일어나기 때문에 일반적으로 800도 이상의 온도에서 서너시간 이상 장시간 이루어진다. 반도체 몰드와의 계면 반응도 동일한 반응 과정을 거쳐 발생한다. 따라서 PZT 소결과정의 문제점은 온도가 높을수록 반응 시간이 길수록 더 많이 발생하는 것이 일반적이다. 따라서 이러한 기존 소결반응의 문제점을 제어하는 것은 안정적인 PZT 나노구조 제작에 핵심적인 기술로 많은 연구 그룹에서 시도하고 있으나 현재까지 해결책을 매우 미미하다. 특히 PZT 조성을 제어하여 저온에서 소결하는 방법이 제시되고 있으나 PZT 저온소결의 경우 소결 후 물성이 변하는 경우가 있어 또 다른 문제점을 발생시키는 방법이다. The fundamental reason for this is that the PZT sintering is performed at a temperature of 800 ° C or more for a long period of time of three to four hours or longer because the PZT sintering takes place by the reduction of the grain boundary area between the PZT grains. The interfacial reaction with the semiconductor mold also occurs through the same reaction process. Therefore, the problem of the PZT sintering process is generally that the higher the temperature, the longer the reaction time is. Therefore, controlling the problems of the conventional sintering reaction is a key technology for making stable PZT nanostructures, and many research groups have attempted to solve the problem. In particular, a method of controlling the composition of PZT and sintering at low temperature has been proposed. However, in case of PZT low-temperature sintering, the physical properties after sintering may change.
이에 본 발명은 압전 소재 기둥(사각 기둥과 같은 다각형 기둥과 원형 기둥)를 소결하는 과정에서 발생하는 수축을 최소화하여 초기 기둥구조 형태를 유지하며 동시에 몰드와의 계면 반응을 억제하여 안정적인 압전 소재 기둥을 구현하는 것을 목적으로 한다.Accordingly, the present invention minimizes shrinkage during sintering of a piezoelectric material column (a polygonal column and a circular column such as a quadrangular column), thereby maintaining the initial column structure, and at the same time suppressing the interfacial reaction with the mold, And the like.
이러한 본 발명의 목적을 달성하기 위해서, 본 발명에 따른 압전 소재 기둥은, 소결된 압전 소재 기둥의 일측 단부에서의 소결밀도가 타측 단부에서의 소결밀도보다 높은 것을 특징으로 한다.In order to achieve the object of the present invention, the piezoelectric material column according to the present invention is characterized in that the sintered density at one end of the sintered piezoelectric material column is higher than the sintered density at the other end.
또한, 상기 압전 소재 기둥은 바인더 화합물이 검출되지 않고 압전 소재 만으로 구성되는 것을 특징으로 한다.Further, the piezoelectric material column is characterized in that it is composed of only a piezoelectric material without detecting a binder compound.
또한, 상기 압전 소재는 PZT인 것을 특징으로 한다. Further, the piezoelectric material is PZT.
한편, 본 발명의 목적을 달성하기 위해서, 본 발명에 따른 압전 소재 기둥의 제조 방법은, 복수개의 충진홀이 구비된 몰드를 준비하는 몰드 준비 단계; 고압의 가스 분사압으로 압전 소재의 입자를 상기 몰드의 충진홀의 바닥면에서부터 충진하는 충진 단계; 및 상기 몰드의 충진홀에 충진된 상기 압전 소재를 급속 열처리하여 소결하는 소결 단계를 포함하는 것을 특징으로 한다.According to another aspect of the present invention, there is provided a method of manufacturing a piezoelectric material column, comprising: preparing a mold having a plurality of filling holes; A filling step of filling particles of the piezoelectric material from the bottom surface of the filling hole of the mold with a high-pressure gas injection pressure; And a sintering step of subjecting the piezoelectric material filled in the filling hole of the mold to rapid thermal annealing and sintering.
또한, 상기 충진 단계에서 압전 소재의 입자는 입경이 서로 다른 입자들을 혼합된 것을 특징으로 한다.In the filling step, the particles of the piezoelectric material are mixed with particles having different particle diameters.
또한, 상기 충진 단계에서 상기 가스 분사압은 1 기압 이상 4 기압 이하의 범위를 갖는 것을 특징으로 한다. In the filling step, the gas injection pressure is in the range of 1 atm to 4 atm.
또한, 상기 소결단계에서 상기 급속 열처리 시간은 1분 이상 5분 이내이고, 급속 열처리 온도는 700℃이상 1100℃이하인 것을 특징으로 한다.In the sintering step, the rapid thermal annealing time is 1 minute to 5 minutes, and the rapid thermal annealing temperature is 700 ° C to 1100 ° C.
이상에서 살펴본 바와 같이, 본 발명에 의한 압전 소재 기둥 및 그 제조방법은 압전 소재 기둥(사각 기둥과 같은 다각형 기둥과 원형 기둥)를 소결하는 과정에서 발생하는 수축을 최소화하여 초기 기둥구조 형태를 유지하며 동시에 몰드와의 계면 반응을 억제하여 안정적인 압전 소재 기둥을 구현할 수 있다.As described above, the piezoelectric material column and the manufacturing method thereof according to the present invention minimize the shrinkage occurring in the process of sintering piezoelectric material columns (polygonal columns and circular columns such as square columns) At the same time, the interfacial reaction with the mold is suppressed, and a stable piezoelectric material column can be realized.
도 1은 본 발명의 종래기술을 도시한 도면.1 shows a prior art of the invention;
도 2는 본 발명의 종래기술에 의해 제작된 압전 소재 기둥을 촬영한 도면.Fig. 2 is a photograph of a piezoelectric material column manufactured by the conventional technique of the present invention. Fig.
도 3은 본 발명의 바람직한 실시예에 따른 압전 소재 입자를 분사하는 장치를 도시한 도면.3 is a view showing an apparatus for jetting piezoelectric material particles according to a preferred embodiment of the present invention.
도 4는 본 발명의 바람직한 실시예에 따른 몰드의 충진홀에 압전 소재 입자가 충전되기 전 상태를 도시한 도면.4 is a view showing a state before a piezoelectric material particle is filled in a filling hole of a mold according to a preferred embodiment of the present invention.
도 5는 본 발명의 바람직한 실시예에 따른 충진홀에 충진된 압전 소재를 소결하여 압전 소재 기둥을 제작한 것으로 도시한 도면.5 is a view showing a piezoelectric material column manufactured by sintering a piezoelectric material filled in a filling hole according to a preferred embodiment of the present invention.
도 6은 본 발명의 바람직한 실시예에 따른 몰드의 충진홀에 압전 소재가 충진된 상태를 촬영한 도면.FIG. 6 is a view showing a state where a piezoelectric material is filled in a filling hole of a mold according to a preferred embodiment of the present invention. FIG.
도 7은 본 발명의 바람직한 실시예에 따라 경계면(소결이 된 부분과 뜯겨져 나간 부분)을 촬영한 도면.FIG. 7 is a view showing a boundary surface (a portion that is sintered and a portion that is torn out) in accordance with a preferred embodiment of the present invention;
도 8, 9는 본 발명의 바람직한 실시예에 따른 충진홀에 충진된 압전 소재를 급속 열처리한 이후의 압전 소재 기둥을 활영한 도면.8 and 9 are views showing a piezoelectric material column after a rapid heat treatment of a piezoelectric material filled in a filling hole according to a preferred embodiment of the present invention.
이하의 내용은 단지 발명의 원리를 예시한다. 그러므로 당업자는 비록 본 명세서에 명확히 설명되거나 도시되지 않았지만 발명의 원리를 구현하고 발명의 개념과 범위에 포함된 다양한 장치를 발명할 수 있는 것이다. 또한, 본 명세서에 열거된 모든 조건부 용어 및 실시 예들은 원칙적으로, 발명의 개념이 이해되도록 하기 위한 목적으로만 명백히 의도되고, 이와 같이 특별히 열거된 실시 예들 및 상태들에 제한적이지 않는 것으로 이해되어야 한다.The following merely illustrates the principles of the invention. Therefore, those skilled in the art will be able to devise various apparatuses which, although not explicitly described or shown herein, embody the principles of the invention and are included in the concept and scope of the invention. It is also to be understood that all conditional terms and examples recited in this specification are, in principle, explicitly intended only for the purpose of enabling the inventive concept to be understood, and not to be construed as limited to such specifically recited embodiments and conditions .
상술한 목적, 특징 및 장점은 첨부된 도면과 관련한 다음의 상세한 설명을 통하여 보다 분명해 질 것이며, 그에 따라 발명이 속하는 기술분야에서 통상의 지식을 가진 자가 발명의 기술적 사상을 용이하게 실시할 수 있을 것이다.BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: .
압전 소재를 이용한 지문센서를 제작할 때 Si 웨이퍼와 같은 반도체 기판을 몰드로 사용하며 이러한 몰드 방식으로 압전 소재 기반 지문센서를 제작할 경우 반도체 웨이퍼를 식각하여 몰드를 제작하고 그 몰드에 압전 소재 등 압전 소재를 충진하여 나노구조(사각 기둥과 같은 다각형 나노구조 및 원형이나 타원형 기둥 등)를 제작하는 과정이 반드시 필요하다. 이러한 과정에서 초기 압전 소재를 반도체 몰드에 충진해야 하며 충진 후에는 열처리 공정을 통해서 압전 소재 물질을 소결(Sintering)해야 한다. 이렇게 소결된 압전 소재 나노 구조가 초음파 지문센서에서 필요한 구조로 사용될 수 있다. When manufacturing a fingerprint sensor using a piezoelectric material, a semiconductor substrate such as a Si wafer is used as a mold. When a piezoelectric material-based fingerprint sensor is manufactured by such a mold method, a semiconductor wafer is etched to form a mold, and a piezoelectric material It is necessary to fill the nano structure (a polygonal nano structure such as a quadrangular column and a circular or elliptic column). In this process, the initial piezoelectric material should be filled in the semiconductor mold, and after the filling, the piezoelectric material should be sintered through a heat treatment process. The sintered piezoelectric material nanostructure can be used as a structure required for an ultrasonic fingerprint sensor.
그러나 압전 소재 나노구조는 수 um에서 수백 um까지 모양과 형태가 다양하지만 일정한 주기를 갖고 배열되어야 초음파 지문센서로 동작할 수 있다. 따라서 단위가 nm에서 um까지 다양한 크기의 주기를 갖는 나노구조를 제작하는 것이 핵심 기술이다. However, piezoelectric material nanostructures can be operated as an ultrasonic fingerprint sensor in a variety of shapes and shapes ranging from a few um to a few hundred um, but with a constant periodicity. Therefore, it is a key technology to fabricate a nanostructure with a period of various sizes ranging from nm to um.
그러나 실제 압전 소재 나노구조 소결과정에서 주기성이 무너지는 이유는 첫째 소결 과정 중에 압전 소재의 수축이 발생한다. 이는 압전 소재 소결의 원리상 당연히 일어나는 과정이다. 또한 일반적으로 사용하는 압전 소재는 압전 소재 외에 다양한 바인더를 섞어 사용하기 때문에 소결과정에서 바인더 부피만큼 더 많은 수축이 발생한다. 두 번째 압전 소재 나노구조 소결 문제점은 계면 반응의 경우 고온의 800℃도 이상의 소결온도에서 장시간 소결하는 과정에서 반드시 발생한다. 또한 이러한 고온 소결 반응은 압전 소재 소결 수축에 직접적인 원인이 된다. 따라서 본 발명에서는 반응 속도론적 측면에서 급속 열처리 공정을 적용하여 계면 반응 억제와 함께 수축을 혁신적으로 감소시킬 수 있는 방법을 제안하고자 한다. However, the reason why the periodicity is collapsed during the sintering process of the piezoelectric material nanostructure is that the piezoelectric material shrinks during the first sintering process. This is a natural course of the piezoelectric material sintering principle. In addition, since piezoelectric materials used in general use a variety of binders in addition to piezoelectric materials, more shrinkage occurs in the binder volume during the sintering process. The second piezoelectric material nanostructure sintering problem necessarily occurs during the long sintering process at the sintering temperature of 800 ° C or higher in the case of the interfacial reaction. These high-temperature sintering reactions also directly cause sintering shrinkage of the piezoelectric material. Therefore, in the present invention, a rapid thermal annealing process is applied in the aspect of reaction kinetics to propose a method that can reduce the interfacial reaction and reduce the shrinkage in an innovative manner.
본 발명의 바람직한 실시예에 따른 압전 소재 기둥의 제조방법은 압전 소재 기둥(사각 기둥과 같은 다각형 기둥과 원형 기둥)를 소결하는 과정에서 발생하는 수축을 최소화하여 초기 기둥구조 형태를 유지하며 동시에 몰드와의 계면 반응을 억제하여 안정적인 압전 소재 기둥을 구현하기 위하여 바인더를 사용하지 않고 입자 상태의 압전 소재를 고압의 가스 분사압을 이용하여 몰드의 충진홀에 충진한다는 점에서 특징이 있다.The method of manufacturing a piezoelectric material column according to a preferred embodiment of the present invention minimizes shrinkage generated in the process of sintering a piezoelectric material column (a polygonal column and a circular column such as a quadrangular column), thereby maintaining the initial column structure, The piezoelectric material of the particle state is filled in the filling hole of the mold by using the high-pressure gas injection pressure without using a binder in order to realize a stable piezoelectric material column by suppressing the interfacial reaction of the piezoelectric material.
압전 소재 입자를 서로 묶어주는 역할을 하는 바인더(binder, 고분자 폴리머)를 압전 소재 입자와 혼합하면, 전체적인 유동성을 향상될 수 있으나 여러가지 문제점을 가지게 된다. 바인더가 압전 소재 입자 외각을 코팅하는 구조의 경우 전체적인 압전 소재입자의 크기가 실제로 증가하는 효과를 주기 때문에 입자간 결합력은 높아지지만 소결과정에서 외부를 둘러싼 코팅 부피만큼 수축하게 되어 전체적으로 압전 소재 소결 후 부피 감소가 크게 일어나는 문제점을 일으키는 단점이 있다(도 2 참조). 또한 충진홀의 바닥부에서 미처 제거되지 못한 바인더가 고온에서 버닝되어 바인더 화합물의 형태로 잔존하게 되어 압전 기능을 저하시키는 단점이 있다.When a binder (polymer polymer) that binds piezoelectric material particles to each other is mixed with the piezoelectric material particles, the overall fluidity can be improved, but it has various problems. In the case of the structure in which the binder coats the outer periphery of the piezoelectric material particles, the size of the piezoelectric material particle actually increases, so that the bonding force between the particles increases. However, the sintering process shrinks by the coating volume surrounding the outer portion, (See Fig. 2). In addition, the binder, which has not yet been removed from the bottom of the filling hole, is burned at a high temperature and remains in the form of a binder compound, which deteriorates the piezoelectric function.
본 발명의 바람직한 실시예서는 바인더를 사용하는 것을 부정적으로 인식하고 입자 상태의 압전 소재만을 몰드의 충진홀에 충진하는 방법을 강구하게 된 것이다. 다시 말해 압전 소재 기둥을 제작함에 있어서는 바인더를 사용하지 않는다. 다만 바인더를 사용하지 않고 파우더 형태의 입자만으로 구성된 압전 소재를 몰드의 충진홀에 충진하기 위해서는 압전 소재의 충진홀에서의 유출 문제 및 공극률 문제를 해결해야 한다. 즉, 파우더 형태의 입자만으로 구성된 압전 소재를 몰드의 충진홀에 충진함에 있어서, 충진홀에 사전에 충진된 압전 소재 입자가 후에 충진되는 압전 소재 입자에 의해 유출되지 않도록 하여야 한다. 또한 사전에 충진된 압전 소재 입자들 주변에 공기가 잔존하는 경우라면 잔존하는 공기압에 의해 후에 충진되는 압전 소재의 입자가 제대로 충진되지 않거나 충진되더라도 소결과정에서 수축률이 크게 증가하는 문제를 해결하여야 한다.In a preferred embodiment of the present invention, the use of a binder is negatively recognized, and only a piezoelectric material in a particle state is filled in a filling hole of a mold. In other words, no binder is used in the production of piezoelectric columns. However, in order to fill the filling hole of the mold with the piezoelectric material composed only of the powder type particles without using the binder, the leakage problem and the porosity problem in the filling hole of the piezoelectric material should be solved. That is, in filling the filling hole of the mold with the piezoelectric material composed only of the powder type particles, the piezoelectric material particles previously filled in the filling hole should not be leaked out by the piezoelectric material particles to be filled later. Also, if air remains around the pre-filled piezoelectric particles, it is necessary to solve the problem that the shrinkage rate increases greatly during the sintering process even if the piezoelectric material particles are not properly filled or filled by the remaining air pressure.
이에 본 발명의 바람직한 실시예에서는 고압의 가스 분사압으로 압전 소재의 입자를 몰드의 충진홀에 충진하는 구성을 강구하게 된 것이다. 이 방식은 고압의 가스 분사압으로 충진홀 내부로 유입된 압전 소재의 입자가 사전에 충진된 압전 소재의 입자 표면에 박히면서 적층되기 때문에 충진되면서 압전 소재 입자들간에 결합되는 효과를 가지게 되므로 사전에 충진된 압전 소재의 입자들의 유출을 방지할 수 있게 되고, 압전 소재 입자들간의 공극률을 줄이기 위해 입경이 서로 다른 압전 소재 입자들을 이용함으로써 수축률을 최소화시킬 수 있게 된다. Accordingly, in a preferred embodiment of the present invention, a configuration is adopted in which the particles of the piezoelectric material are filled in the filling holes of the mold with a high-pressure gas injection pressure. In this method, since the particles of the piezoelectric material introduced into the filling hole by the high-pressure gas injection pressure are stacked and laminated on the surface of the piezoelectric material filled in advance, The shrinkage rate can be minimized by using the piezoelectric material particles having different particle diameters in order to reduce the porosity between the piezoelectric material particles.
종래 green sheet나 슬러리(slurry)를 형태를 이용하여 압전 소재를 충진홀에 충진하는 방식은 충진홀의 상부에 하부로 압전 소재를 밀어 넣는 탑-다운 방식이었다면, 본 발명의 바람직한 실시예에 따른 방식은 압전 소재 입자를 충진홀의 하부에서 상부로 채워나가는 바텁-업 방식이라는 점에서 충진 방식에 차이가 있게 된다.Conventionally, a method of filling a piezoelectric material into a filling hole by using a shape of a green sheet or a slurry is a top-down method in which a piezoelectric material is pushed down into a top portion of a filling hole. Up method in which the piezoelectric material particles are filled from the lower part to the upper part of the filling hole.
또한 본 발명의 바람직한 실시예는 압전 소재 기둥이 충진홀의 형상을 유지할 수 있도록 기둥 표면에서의 소결 밀도를 내부보다 높도록 충진홀에 충진된 압전 소재를 급속 열처리한다는 점에서 특징이 있다. 이를 통해 압전 소재 각각의 기둥의 수축이 최소화되어 각각이 복수개의 압전 소재 기둥이 동일한 기하학적 형상을 가지게 되어 동일한 압전 특성을 보이도록 한다는 점에서 특징이 있다.The preferred embodiment of the present invention is characterized in that the piezoelectric material filled in the filling hole is subjected to rapid thermal annealing so that the sintered density on the column surface is higher than that of the inside so that the piezoelectric material column can maintain the shape of the filling hole. In this way, the shrinkage of each of the pillars of the piezoelectric material is minimized, so that each of the plurality of piezoelectric material pillars has the same geometrical shape, thereby exhibiting the same piezoelectric characteristics.
이하, 본 발명의 바람직한 실시예를 첨부된 도면들을 참조하여 상세히 설명한다. 본 발명을 설명함에 있어, 관련된 공지 구성 또는 기능에 대한 구체적인 설명이 본 발명의 요지를 흐릴 수 있다고 판단되는 경우에는 그 상세한 설명은 생략하기로 한다. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.
본 발명의 바람직한 실시예에 따른 압전 소재 기둥의 제조방법은 복수개의 충진홀(410)이 구비된 몰드(400)를 준비하는 몰드 준비 단계; 고압의 가스 분사압으로 압전 소재의 입자(500)를 몰드(400)의 충진홀(410)의 바닥면에서부터 충진하는 충진 단계; 및 상기 몰드(400)의 충진홀(410)에 충진된 압전 소재를 급속 열처리하여 소결하는 소결 단계를 포함한다.A method of manufacturing a piezoelectric material column according to a preferred embodiment of the present invention includes: preparing a mold 400 having a plurality of filling holes 410; A filling step of filling the piezoelectric material particles 500 from the bottom surface of the filling hole 410 of the mold 400 with a high-pressure gas injection pressure; And a sintering step of subjecting the piezoelectric material filled in the filling hole 410 of the mold 400 to rapid thermal annealing and sintering.
충진홀(410)은 그 단면 형상이 원형, 다각형의 형태일 수 있으나 이에 한정되는 것은 아니다. The filling hole 410 may have a circular or polygonal cross-sectional shape, but is not limited thereto.
도 3을 참조하면, 분사노즐(300)은 분사압 생성부(100)에 연결되며 분사압 생성부(100)는 고압의 가스압을 생성한다. 가스 분사압이 소정 범위의 하한값보다 낮은 경우에는 압전 소재 입자가 충진홀(410) 내부에서 다른 압전 소재 입자들과의 결합력이 약하여 제대로 적층되지 않게 되고, 가스 분사압이 소정 범위의 상한값보다 높은 경우에는 가스 분사압에 의해 충진홀(410)의 측벽이 파손되는 염려가 발생하게 되므로, 가스 분사압은 소정 범위내로 제한되는 것이 바람직하다. 본 발명의 바람직한 실시예에서는 바람직하게 가스 분사압은 1 기압 이상 50기압 이하의 범위를 갖는다. 이와 같은 가스 분사압을 통해 압전 소재 입자들의 안정적인 충진이 가능하게 되고 공극률을 최소화할 수 있게 된다.Referring to FIG. 3, the injection nozzle 300 is connected to the injection pressure generator 100, and the injection pressure generator 100 generates a high-pressure gas pressure. When the gas injection pressure is lower than the lower limit of the predetermined range, the piezoelectric material particles are not properly stacked in the filling hole 410 because of their weak bonding force with other piezoelectric material particles. When the gas injection pressure is higher than the upper limit value of the predetermined range The side wall of the filling hole 410 may be damaged by the gas injection pressure. Therefore, it is preferable that the gas injection pressure is limited within a predetermined range. In a preferred embodiment of the present invention, the gas injection pressure preferably ranges from 1 atm to 50 atm. Such gas injection pressure enables stable filling of the piezoelectric material particles and minimizes porosity.
입자 저장부(200)는 압전 소재를 입자 형태로 저장한다. 압전 소재는 티탄산 지르콘산 연(타이타늄산 지르콘산 연) [PZT, lead zirconate titanate ]일 수 있다. 다만 이에 한정되는 것은 아니다. 압전 소재 입자(500)의 크기는 소정 범위의 상한값보다 크면 공극률이 커져서 수축률이 높아지므로 바람직하지 않고, 크기가 소정 범위의 하한값보다 작으면 충진 효율이 저하되어 바람직하지 않다. 본 발명의 바람직한 실시예에 따르면 압전 소재 입자(500)의 크기는 수십 nm 이상 5μm 이하의 입자 크기를 갖는 것이 바람직하며, 보다 바람직하게는 1μm 이하 것이 바람직하다.The particle storage unit 200 stores the piezoelectric material in the form of particles. The piezoelectric material may be lead titanate zirconate titanate (PZT, lead zirconate titanate). However, the present invention is not limited thereto. If the size of the piezoelectric material particles 500 is larger than the upper limit of the predetermined range, the porosity increases and the shrinkage rate increases. If the size is smaller than the lower limit of the predetermined range, the filling efficiency is lowered. According to a preferred embodiment of the present invention, the size of the piezoelectric material particles 500 preferably has a particle size of several tens nm or more and 5 μm or less, more preferably 1 μm or less.
입자 저장부(200)는 서로 다른 입경을 갖는 압전 소재 입자(500)가 혼합되어 구비될 수 있다. 입자 저장부(200)에 저장된 압전 소재 입자는 분사압 생성부(100)에 생성된 고압의 가스압에 혼입되어 분사노즐(300)을 통해 토출된다. 분사노즐(300)은 서로 다른 입경을 갖는 압전 소재 입자(500)를 몰드(400)측으로 분사한다. 압전 소재 입자(500)들의 입경들이 서로 차이가 있게 되므로, 충진홀(410)에 충진되는 압전 소재 입자(500)들의 공극률을 줄일 수 있게 되어 소결 시 수축률을 최소화할 수 있다.The particle storage part 200 may be provided by mixing piezoelectric material particles 500 having different particle diameters. The piezoelectric material particles stored in the particle storage unit 200 are mixed with the high-pressure gas pressure generated in the injection-pressure generating unit 100 and are discharged through the injection nozzle 300. The injection nozzle 300 injects the piezoelectric material particles 500 having different particle diameters toward the mold 400 side. Since the particle diameters of the piezoelectric material particles 500 are different from each other, the porosity of the piezoelectric material particles 500 filled in the filling hole 410 can be reduced, and the shrinkage rate during sintering can be minimized.
도 4를 참조하면, 분사노즐(300)을 통해 토출된 압전 소재 입자(500)는 몰드(400)의 충진홀(410) 내부로 유입되어 적층된다. 다시 말해 충진홀(410) 내부 바닥면에 압전 소재 입자(500)가 충진이 되면, 연속적으로 충진홀(410) 내부로 유입되는 압전 소재 입자(500)는 고압의 가스압으로 인해 기 충진된 압전 소재 입자(500)와 결합되면서 적층되게 된다. 압전 소재 입자(500)의 충진 속도는 20μm/sec 이상으로 수행된다. Referring to FIG. 4, the piezoelectric material particles 500 discharged through the injection nozzle 300 are introduced into the filling holes 410 of the mold 400 and stacked. In other words, when the piezoelectric material particles 500 are filled in the bottom surface of the filling hole 410, the piezoelectric material particles 500 continuously flowing into the filling hole 410 are filled with the piezoelectric material Particles 500 are combined with each other. The filling speed of the piezoelectric material particles 500 is 20 mu m / sec or more.
사전에 충진된 압전 소재 입자(500)의 표면에 결합되면서 적층되기 때문에 압전 소재 입자(500)들이 서로 뭉치는 효과를 가지게 되고, 이를 통해 사전에 충진된 압전 소재의 입자들의 유출을 방지할 수 있게 된다. Since the piezoelectric material particles 500 are stacked while being bonded to the surface of the piezoelectric material particles 500 filled in advance, the piezoelectric material particles 500 have an effect of aggregating the piezoelectric material particles 500, thereby preventing leakage of the particles of the previously filled piezoelectric material do.
또한 압전 소재 입자(500)는 서로 다른 입경을 가지고 있기 때문에 압전 소재 입자(500)들이 적층되었을 때의 공극률을 줄일 수 있게 된다. 특히 상대적으로 작은 입경을 갖는 압전 소재 입자(500)는 고압의 가스압에 의해 기 충진된 상대적으로 큰 입경을 갖는 압전 소재 입자(500)들 사이를 통과하여 보다 아래쪽으로 이동할 수 있게 되므로 공극률을 효과적으로 줄일 수 있게 된다. 공극률이 효과적으로 감소되므로 소결시 수축률을 최소화시킬 수 있게 된다(도 6 참조). Further, since the piezoelectric material particles 500 have different particle diameters, the porosity of the piezoelectric material particles 500 when they are laminated can be reduced. Particularly, the piezoelectric material particles 500 having a relatively small particle size can pass through between the piezoelectric material particles 500 having a relatively large particle size filled by the gas pressure of a high pressure and move downwardly, thereby effectively reducing the porosity . The porosity is effectively reduced, so that the shrinkage rate during sintering can be minimized (see FIG. 6).
압전 소재 입자(500)를 몰드(400)의 충진홀(410)에 충진하는 공정이 완료가 되면, 충진홀(410)에 충진된 압전 소재를 열처리하여 압전 소재 기둥(600)을 제작하게 된다. When the process of filling the piezoelectric material particles 500 into the filling hole 410 of the mold 400 is completed, the piezoelectric material filled in the filling hole 410 is heat-treated to produce the piezoelectric material column 600.
여기서 장시간 열처리 공정이 진행된다면 압전 소재의 표면과 내부가 모두 유사한 소결 밀도를 갖으면서 전체적으로 수축이 일어나게 된다. 이 경우에는 소결된 압전 소재 기둥(600)이 몰드(400)의 충진홀(410)의 형태를 유지하지 못하게 되어 압전 소재 기둥(600)으로서의 기능을 제대로 수행할 수 없게 된다. 또한 압전 소재 외에 다양한 바인더를 섞어 제작된 압전 소재 기둥은, 바인더가 고온에서 버닝되어 바인더 화합물 형태로 잔존하게 되고 이러한 바인더 화합물은 압전 소재 기둥의 하부쪽에 집중적으로 분포하게 된다. 따라서 압전 소재 외에 다양한 바인더를 섞어 제작된 압전 소재 기둥을 장시간 열처리 공정을 진행하면, 표면과 내부는 유사한 소결밀도를 갖지만, 압전 소재 기둥의 전체적인 형상이 초기 형태를 유지하지 못하고 3차원적으로 수축되어 제 각각의 변형된 형태를 갖게 된다. Here, if the heat treatment process is performed for a long time, the surface and the interior of the piezoelectric material have similar sintered densities, resulting in contraction as a whole. In this case, the sintered piezoelectric material column 600 can not maintain the shape of the filling hole 410 of the mold 400 and can not function properly as the piezoelectric material column 600. In addition, the piezoelectric material column prepared by mixing various binders in addition to the piezoelectric material, the binder is burned at a high temperature to remain in the form of a binder compound, and such a binder compound is concentrated on the lower side of the piezoelectric material column. Therefore, when a piezoelectric material column made of a mixture of piezoelectric materials and a binder is subjected to a heat treatment process for a long time, the surface and the interior have similar sintering densities, but the overall shape of the piezoelectric material column does not maintain its initial shape and contracts in three dimensions Each having its own modified form.
반면에 본 발명의 바람직한 실시예는 소결된 압전 소재 기둥(600)의 표면에서의 소결밀도가 내부 소결밀도 보다 높도록 하여 압전 소재 기둥(600)이 충진홀(410)의 형상을 유지할 수 있도록 한 것이다. 도 7은 압전소재 기둥(600) 표면과 내부의 소결 밀도 차이를 확인하기 위하여 경계면(소결이 된 부분과 뜯겨져 나간 부분)을 촬영한 도면이다. 도 7을 참조하면, 압전 소재 기둥(600)의 표면(A)에서의 소결밀도는 높고, 그 내부(B)의 소결 밀도는 상대적으로 낮다는 것을 확인할 수 있다. 이처럼 압전 소재 기둥(600) 표면(A)의 급격한 소결로 압전 소재 기둥(600)의 부피 축소를 최소화할 수 있게 된다. 압전 소재 기둥(600)이 초음파 지문센서에 이용될 경우에는 양측 단부에는 각각 전극이 형성되고 표면(A)과 내부(B)는 상,하 반전될 수 있으므로, 이 경우 압전 소재 기둥(600) 일측 단부에서의 소결 밀도는 타측 단부에서의 소결 밀도보다 높게 된다. 다시 말해, 압전 소재 기둥은, 소결된 압전 소재 기둥의 일측 단부에서의 소결밀도가 타측 단부에서의 소결밀도보다 높은 구성을 갖게 된다. On the other hand, in the preferred embodiment of the present invention, the sintered density on the surface of the sintered piezoelectric material column 600 is higher than the inner sintered density so that the piezoelectric material column 600 can maintain the shape of the filling hole 410 will be. FIG. 7 is a view of a boundary surface (a part sintered and a part torn off) to check the difference in sintered density between the surface of the piezoelectric material column 600 and the inside thereof. Referring to FIG. 7, it can be seen that the sintered density at the surface (A) of the piezoelectric material column (600) is high and the sintered density of the inside (B) is relatively low. Thus, the rapid sintering of the surface (A) of the piezoelectric material column 600 minimizes the volume reduction of the piezoelectric material column 600. When the piezoelectric material column 600 is used for an ultrasonic fingerprint sensor, electrodes are formed at both ends of the piezoelectric material column 600, and the surface A and the inside B can be reversed up and down. The sintered density at the end portion becomes higher than the sintered density at the other end portion. In other words, the piezoelectric material column has a configuration in which the sintered density at one end of the sintered piezoelectric material column is higher than the sintered density at the other end.
또한, 바인더를 채택하지 않고 오로지 압전 소재 입자(500)만으로 압전 소재 기둥(600)을 제작하므로 압전 소재 기둥(600)에서는 바인더 화합물이 검출되지 않는다. 따라서 초음파 지문센서에 본 발명의 바람직한 실시예에 따른 압전 소재 기둥을 채용할 경우에는, 초음파 지문센서의 성능을 향상시킬 수 있게 된다(도 8, 9 참조).In addition, since the piezoelectric material column 600 is manufactured using only the piezoelectric material particles 500 without adopting a binder, a binder compound is not detected in the piezoelectric material column 600. [ Therefore, when the piezoelectric material column according to the preferred embodiment of the present invention is employed in the ultrasonic fingerprint sensor, the performance of the ultrasonic fingerprint sensor can be improved (see FIGS. 8 and 9).
이를 위해 본 발명의 바람직한 실시예는 몰드(400)의 충진홀(410)에 충진된 압전 소재를 급속 열처리하여 소결하는 공정을 수행한다. 여기서 급속 열처리 시간은 1분 이상 5분 이내이고, 급속 열처리 온도는 700℃이상 1100℃이하인 것이 바람직하다. To this end, the preferred embodiment of the present invention performs a rapid thermal annealing process for sintering the piezoelectric material filled in the filling hole 410 of the mold 400. The rapid thermal annealing time is preferably from 1 minute to 5 minutes, and the rapid thermal annealing temperature is preferably 700 ° C to 1100 ° C.
이 경우 가스 분위기는 상압 조건인 것이 바람직하다. 급속 열처리를 위한 히터는 외부에 별도로 구비되므로 히터와 몰드가 직접 접촉되지 않는다. 히터를 작동시켜 압전 소재 기둥(600)의 표면에서의 소결 밀도를 높게 하기 위해서는, 가스 분위기가 충분한 열의 대류가 이루어질 수 있는 분위기이어야 한다. 가스 분위기가 상압 조건인 경우에는 열의 대류가 충분하게 이루어지기 때문에 본 발명의 바람직한 실시예에서 목적하는 바와 같은 압전 소재 기둥(600)의 표면에서의 급속 열처리가 가능하게 된다.In this case, it is preferable that the gas atmosphere be at atmospheric pressure. Since the heater for rapid thermal annealing is separately provided outside, the heater and the mold are not in direct contact with each other. In order to increase the sintering density at the surface of the piezoelectric material column 600 by operating the heater, the atmosphere should be such that the gas atmosphere can sufficiently conduct convection of heat. If the gas atmosphere is at atmospheric pressure, the convection of the heat is sufficiently performed, so that rapid heat treatment on the surface of the piezoelectric material column 600 as desired in the preferred embodiment of the present invention becomes possible.
장시간 열처리 공정이 진행된다면 표면과 내부가 모두 유사한 소결 밀도를 갖으면서 전체적으로 3차원적인 수축이 일어나지만 본 발명의 바람직한 실시예에서는 짧은 시간 동안에 열처리를 진행하기 때문에 압전 소재 구조가 수축이 일어날 만큼 충분한 반응 시간이 주어지지 않는다. 따라서 열처리 후 압전 소재 구조의 수축은 최소화되며, 계면 반응 역시 반응시간이 짧아서 충분히 거의 일어나지 않았다. 더욱이 바인더를 사용하지 않기 때문에 계면의 반응은 억제되어 안정적인 압전 소재 구조 소결이 가능하다.If the heat treatment process is performed for a long time, the surface and the interior have similar sintered densities and the whole three-dimensional shrinkage occurs. However, in the preferred embodiment of the present invention, since the heat treatment is performed for a short time, Time is not given. Therefore, the shrinkage of the piezoelectric material structure after heat treatment is minimized, and the interfacial reaction is also hardly occurred due to the short reaction time. Furthermore, since the binder is not used, the reaction at the interface is suppressed and stable piezoelectric material structure sintering is possible.
이러한 본 발명의 제조방법을 적용한 결과 압전 소재 소결 반응에 따른 수축을 50um x 50 um x 180um 정도의 크기를 갖는 압전 소재 사각 기둥 형태의 경우 수축이 2um 이내로 최소화할 수 있었다. 또한 양산성도 매우 우수하여 일정한 시간동안 많은 량의 압전 소재 소결을 진행할 수 있으며, 재현성 또한 매우 우수한 결과를 얻을 수 있었다. As a result of applying the manufacturing method of the present invention, the shrinkage due to the sintering reaction of the piezoelectric material can be minimized to 2 μm or less in the case of the square shape of the piezoelectric material having the size of about 50 μm × 50 μm × 180 μm. In addition, it is very good in mass productivity, so that a large amount of piezoelectric material can be sintered for a predetermined time, and the reproducibility is also excellent.
전술한 바와 같이, 본 발명의 바람직한 실시 예를 참조하여 설명하였지만, 해당 기술분야의 통상의 기술자는 하기의 특허 청구범위에 기재된 본 발명의 사상 및 영역으로부터 벗어나지 않는 범위 내에서 본 발명을 다양하게 수정 또는 변형하여 실시할 수 있다.While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the following claims Or modified.

Claims (7)

  1. 소결된 압전 소재 기둥의 일측 단부에서의 소결밀도가 타측 단부에서의 소결밀도보다 높은 것을 특징으로 하는 압전 소재 기둥.Wherein the sintered density at one end of the sintered piezoelectric material column is higher than the sintered density at the other end.
  2. 제1항에 있어서,The method according to claim 1,
    상기 압전 소재 기둥은 바인더 화합물이 검출되지 않고 압전 소재 만으로 구성되는 것을 특징으로 하는 압전 소재 기둥.Wherein the piezoelectric material column is composed of only a piezoelectric material without detecting a binder compound.
  3. 제1항에 있어서,The method according to claim 1,
    상기 압전 소재는 PZT인 것을 특징으로 하는 압전 소재 기둥.Wherein the piezoelectric material is PZT.
  4. 복수개의 충진홀이 구비된 몰드를 준비하는 몰드 준비 단계;A mold preparing step of preparing a mold having a plurality of filling holes;
    고압의 가스 분사압으로 압전 소재의 입자를 상기 몰드의 충진홀의 바닥면에서부터 충진하는 충진 단계; 및A filling step of filling particles of the piezoelectric material from the bottom surface of the filling hole of the mold with a high-pressure gas injection pressure; And
    상기 몰드의 충진홀에 충진된 상기 압전 소재를 급속 열처리하여 소결하는 소결 단계를 포함하는 것을 특징으로 하는 압전 소재 기둥의 제조방법.And a sintering step of subjecting the piezoelectric material filled in the filling hole of the mold to rapid thermal annealing and sintering the piezoelectric material.
  5. 제4항에 있어서,5. The method of claim 4,
    상기 충진 단계에서 압전 소재의 입자는 입경이 서로 다른 입자들을 혼합된 것을 특징으로 하는 압전 소재 기둥의 제조방법.Wherein the particles of the piezoelectric material are mixed with particles having different particle diameters in the filling step.
  6. 제4항에 있어서,5. The method of claim 4,
    상기 충진 단계에서 상기 가스 분사압은 1 기압 이상 4 기압 이하의 범위를 갖는 것을 특징으로 하는 압전 소재 기둥의 제조방법.Wherein the gas injection pressure in the filling step ranges from 1 atm to 4 atmospheres.
  7. 제4항에 있어서,5. The method of claim 4,
    상기 소결단계에서 상기 급속 열처리 시간은 1분 이상 5분 이내이고, 급속 열처리 온도는 700℃이상 1100℃이하인 것을 특징으로 하는 압전 소재 기둥의 제조방법.Wherein the rapid thermal annealing time in the sintering step is from 1 minute to 5 minutes, and the rapid thermal annealing temperature is 700 ° C to 1100 ° C.
PCT/KR2018/008779 2017-08-04 2018-08-02 Piezoelectric material column and manufacturing method therefor WO2019027268A1 (en)

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JP2003213451A (en) * 2001-10-11 2003-07-30 National Institute Of Advanced Industrial & Technology Method of fabricating composite structure
KR100805304B1 (en) * 2006-12-15 2008-02-20 한국기계연구원 Preparation method of pzt based thick film deposited using the powder with excess pbo
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