KR20000047386A - Method of fabrication acoustic wave device and acoustic wave device using the same - Google Patents
Method of fabrication acoustic wave device and acoustic wave device using the same Download PDFInfo
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- KR20000047386A KR20000047386A KR1019990013830A KR19990013830A KR20000047386A KR 20000047386 A KR20000047386 A KR 20000047386A KR 1019990013830 A KR1019990013830 A KR 1019990013830A KR 19990013830 A KR19990013830 A KR 19990013830A KR 20000047386 A KR20000047386 A KR 20000047386A
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 15
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 39
- 229910052814 silicon oxide Inorganic materials 0.000 claims abstract description 36
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims abstract description 28
- 239000010937 tungsten Substances 0.000 claims abstract description 28
- 229910052721 tungsten Inorganic materials 0.000 claims abstract description 28
- 238000000034 method Methods 0.000 claims abstract description 23
- 239000010408 film Substances 0.000 claims description 161
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims description 33
- 239000010931 gold Substances 0.000 claims description 31
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 21
- 229910052737 gold Inorganic materials 0.000 claims description 21
- 239000000463 material Substances 0.000 claims description 20
- 239000010409 thin film Substances 0.000 claims description 18
- 239000000758 substrate Substances 0.000 claims description 16
- 239000011787 zinc oxide Substances 0.000 claims description 16
- 239000010936 titanium Substances 0.000 claims description 14
- 229910052782 aluminium Inorganic materials 0.000 claims description 13
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 13
- 229910018487 Ni—Cr Inorganic materials 0.000 claims description 10
- 239000011651 chromium Substances 0.000 claims description 10
- VNNRSPGTAMTISX-UHFFFAOYSA-N chromium nickel Chemical compound [Cr].[Ni] VNNRSPGTAMTISX-UHFFFAOYSA-N 0.000 claims description 10
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 8
- 229910052738 indium Inorganic materials 0.000 claims description 8
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 claims description 8
- 230000001681 protective effect Effects 0.000 claims description 8
- 229910052719 titanium Inorganic materials 0.000 claims description 8
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 7
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 7
- 229910052710 silicon Inorganic materials 0.000 claims description 7
- 239000010703 silicon Substances 0.000 claims description 7
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 claims description 6
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 5
- 230000008859 change Effects 0.000 claims description 5
- 229910052804 chromium Inorganic materials 0.000 claims description 5
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 3
- 229910052709 silver Inorganic materials 0.000 claims description 3
- 239000004332 silver Substances 0.000 claims description 3
- 238000001914 filtration Methods 0.000 abstract description 2
- 239000000126 substance Substances 0.000 abstract 2
- 238000010030 laminating Methods 0.000 abstract 1
- 235000012239 silicon dioxide Nutrition 0.000 abstract 1
- 239000000377 silicon dioxide Substances 0.000 abstract 1
- 238000000151 deposition Methods 0.000 description 8
- 230000008569 process Effects 0.000 description 7
- 239000012528 membrane Substances 0.000 description 4
- 238000001755 magnetron sputter deposition Methods 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- JBRZTFJDHDCESZ-UHFFFAOYSA-N AsGa Chemical compound [As]#[Ga] JBRZTFJDHDCESZ-UHFFFAOYSA-N 0.000 description 2
- 238000005229 chemical vapour deposition Methods 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 238000000206 photolithography Methods 0.000 description 2
- 238000010897 surface acoustic wave method Methods 0.000 description 2
- PIGFYZPCRLYGLF-UHFFFAOYSA-N Aluminum nitride Chemical compound [Al]#N PIGFYZPCRLYGLF-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000010365 information processing Effects 0.000 description 1
- 238000010295 mobile communication Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 229910052594 sapphire Inorganic materials 0.000 description 1
- 239000010980 sapphire Substances 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/25—Constructional features of resonators using surface acoustic waves
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
- H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
- H03H3/08—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of resonators or networks using surface acoustic waves
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02543—Characteristics of substrate, e.g. cutting angles
- H03H9/02574—Characteristics of substrate, e.g. cutting angles of combined substrates, multilayered substrates, piezoelectrical layers on not-piezoelectrical substrate
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/125—Driving means, e.g. electrodes, coils
- H03H9/145—Driving means, e.g. electrodes, coils for networks using surface acoustic waves
- H03H9/14538—Formation
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- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
Description
본 발명은 탄성파 소자에 관한 것으로서, 보다 상세하게는 서로 다른 탄성 임피던스 유전율을 갖는 박막이 순차적으로 반복 적층된 다층막 구조를 갖는 탄성파 소자의 제조방법 및 그에 따라 형성된 탄성파 소자에 관한 것이다.The present invention relates to an acoustic wave device, and more particularly, to a method of manufacturing an acoustic wave device having a multilayered film structure in which thin films having different elastic impedance dielectric constants are sequentially and repeatedly stacked, and the elastic wave devices formed accordingly.
최근 정보처리 장치와 통신기기의 동작속도의 고속화가 요구됨에 따라 신호의 주파수가 고주파(Radio Frequency)대로 높아졌다.Recently, as the speed of the operation of the information processing apparatus and the communication apparatus is required to increase, the frequency of the signal has increased to a radio frequency.
이러한 주파수의 변화에 대응하여, 상기 고주파대에서 동작할 수 있는 필터가 요구되고 있다. 이러한 목적으로 탄성파 소자(Acoustic Wave Device)가 사용된다.In response to such a change in frequency, a filter capable of operating at the high frequency band is required. An acoustic wave device is used for this purpose.
정보시대의 총아라고 할 수 있는 장래의 무선이동통신의 유망성 관점에서 상기 탄성파 소자의 개발은 무한한 가능성을 가지고 있다.In view of the prospect of future wireless mobile communication, which can be regarded as the information age, the development of the acoustic wave device has unlimited possibilities.
상기 탄성파 소자중 FBAR(Film Bulk Acoustic Resonator) 박막형 필터는 반도체 기판인 실리콘(Si) 또는 갈륨비소(GaAs) 기판상에 압전물질(Piezoelectric Material)인 아연산화막(ZnO) 또는 알루미늄나이트라이드(AlN) 박막을 증착하여 압전특성에 의한 공진을 유발시켜 박막형태의 소자를 필터로 구현한 것이다.Among the acoustic wave devices, a FBAR (Film Bulk Acoustic Resonator) thin film filter is a thin film of zinc oxide (ZnO) or aluminum nitride (AlN), which is a piezoelectric material, on a silicon (Si) or gallium arsenide (GaAs) substrate, which is a semiconductor substrate. By depositing to induce the resonance by the piezoelectric properties to implement a thin film element as a filter.
즉, 상기 FBAR은 양 전극 사이에 압전박막을 증착하여 벌크탄성파(Bulk Acoustic Wave)를 유발시켜 공진을 일으키는 원리를 사용한다.That is, the FBAR uses a principle that causes a resonance by generating a bulk acoustic wave by depositing a piezoelectric thin film between both electrodes.
상기 FBAR 제조공정은 실리콘 기판상에 식각정지층인 실리콘산화막(SiO2)을 형성하는 공정; 상기 실리콘산화막상에 하부전극을 위한 알루미늄막, 압전박막인 아연산화막과 상부전극을 위한 알루미늄막을 순차적으로 형성하는 공정; 및 전극과 멤브레인을 형성하는 공정;으로 나눌 수 있다.The FBAR manufacturing process may include forming a silicon oxide film (SiO 2 ) as an etch stop layer on a silicon substrate; Sequentially forming an aluminum film for a lower electrode, a zinc oxide film as a piezoelectric film, and an aluminum film for an upper electrode on the silicon oxide film; And forming a membrane with the electrode.
상기 멤브레인의 형성은 상기 실리콘 기판의 반대면을 이방성 식각(Isotropic Etching)방법으로 식각정지층인 실리콘산화막이 노출되도록하여 식각케비티(Etching Cavity)를 형성하는 것이다.The formation of the membrane is to form an etching cavity by exposing the silicon oxide film, which is an etch stop layer, to an opposite surface of the silicon substrate by an isotropic etching method.
그러나 상기 멤브레인을 이용한 FBAR은 공정의 번거로움과 개별소자의 절단시 상기 멤브레인의 약함으로 인하여 소자가 파손되는 문제점이 있었다. 또한 탄성파(Acoustic Wave)에너지의 손실로 공진 특성이 감소하는 문제점이 있었다.However, the FBAR using the membrane has a problem in that the device is damaged due to the troublesome process and the weakness of the membrane when the individual device is cut. In addition, there is a problem that the resonance characteristics are reduced due to the loss of acoustic wave energy.
본 발명의 목적은, 기판의 종류에 무관하게 높은 전기적 반사계수(Q)를 갖으며, 광대역의 필터링 영역을 갖는 탄성파 소자의 제조방법 및 그에 따라 형성된 탄성파 소자를 제공하는 데 있다.SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing an acoustic wave element having a high electrical reflection coefficient Q and having a wideband filtering region regardless of the type of substrate, and the elastic wave element formed thereby.
도1 내지 도5는 본 발명에 의한 탄성파 소자의 제조방법을 설명하기 위한 공정단면도들이다.1 to 5 are process cross-sectional views illustrating a method of manufacturing an acoustic wave device according to the present invention.
※도면의 주요부분에 대한 부호의 설명※ Explanation of symbols for main parts of drawing
2 ; 실리콘 기판 4 ; 실리콘산화막2 ; Silicon substrate 4; Silicon oxide film
6 ; 텅스텐막 7 : 탄성 반사층6; Tungsten Film 7: Elastic Reflective Layer
8, 18 ; 버퍼막 10 ; 바텀전극8, 18; Buffer film 10; Bottom electrode
12, 16 ; 보호막 14 ; 아연산화막12, 16; Protective film 14; Zinc oxide film
20 ; 탑전극20; Top electrode
상기 목적을 달성하기 위한 본 발명에 따른 탄성파 소자의 제조방법은 기판상에 제 1 탄성 임피던스(First Acoustic Impedence)를 갖으며, 탄성 파장의 0.12 내지 0.13 배의 두께를 갖는 실리콘산화(SiO2)막과 상기 제 1 탄성 임피던스보다 큰 제 2 탄성 임피던스를 갖으며, 탄성 파장의 0.2 내지 0.3 배의 두께를 갖는 텅스텐(W)막을 번갈아 적층하며, 최상부층은 상기 실리콘산화막이 되도록 적층하여 전체적으로 홀수층으로 이루어지는 탄성 반사층(Acoustic Reflecting Layer)을 형성하는 단계; 상기 탄성 반사층상에 바텀전극(Bottom Electrode)을 형성하는 단계; 상기 바텀전극상에 상기 전체 탄성 반사층의 0.45 내지 0.55 배의 두께로 압전물질을 형성하는 단계; 및 상기 압전물질상에 탑전극(Top Electrode)을 형성하는 단계를 구비하여 이루어진다.A method for manufacturing an acoustic wave device according to the present invention for achieving the above object has a first acoustic impedance on the substrate, a silicon oxide (SiO 2 ) film having a thickness of 0.12 to 0.13 times the elastic wavelength And a tungsten (W) film having a second elastic impedance greater than the first elastic impedance and having a thickness of 0.2 to 0.3 times the elastic wavelength, and alternately stacked, and the uppermost layer is laminated so as to be the silicon oxide film. Forming an acoustic reflecting layer; Forming a bottom electrode on the elastic reflective layer; Forming a piezoelectric material on the bottom electrode at a thickness of 0.45 to 0.55 times the total elastic reflection layer; And forming a top electrode on the piezoelectric material.
상기 탄성 반사층은 상기 실리콘산화막과 상기 텅스텐막을 번갈아 7층 내지 11층으로 형성할 수 있다.The elastic reflective layer may be formed of seven to eleven layers of the silicon oxide film and the tungsten film alternately.
상기 바텀전극을 이루는 박막은 금(Au)막, 알루미늄(Al)막, 텅스텐(W)막, 은(Ag)막 및 인듐(In)막중에서 어느 하나일 수 있으며, 상기 탑전극을 이루는 박막은 금(Au)막, 알루미늄(Al)막 및 텅스텐(W)막중에서 어느 하나일 수 있으며, 상기 압전물질은 아연산화막(ZnO) 또는 알루미늄나이트라이드막(AlN)인 것이 바람직하다.The thin film forming the bottom electrode may be any one of a gold (Au) film, an aluminum (Al) film, a tungsten (W) film, a silver (Ag) film, and an indium (In) film. The gold (Au) film, aluminum (Al) film and tungsten (W) film may be any one, and the piezoelectric material is preferably a zinc oxide film (ZnO) or an aluminum nitride film (AlN).
상기 바텀전극으로 금막을 사용하는 경우는 상기 탄성 반사층과 상기 금막사이에 티타늄(Ti)막, 크롬(Cr)막 및 니켈크롬(NiCr)막중에서 어느 하나를 버퍼막으로 더 형성하는 것이 바람직하다.In the case of using the gold film as the bottom electrode, it is preferable to further form any one of a titanium (Ti) film, a chromium (Cr) film and a nickel chromium (NiCr) film as a buffer between the elastic reflective layer and the gold film.
상기 바텀전극과 상기 압전물질 사이 및 상기 압전물질과 탑전극 사이에 외부 온도 변화로부터 소자의 공진 주파수 변동을 방지하기 위한 보호막으로 실리콘산화막(SiO2)을 더 형성하는 것이 바람직하다.It is preferable to further form a silicon oxide film (SiO 2 ) as a protective film for preventing the resonance frequency variation of the device from external temperature change between the bottom electrode and the piezoelectric material and between the piezoelectric material and the top electrode.
상기 목적을 달성하기 위한 본 발명의 탄성파소자 제조방법에 의해 제조된 탄성파소자는 기판; 제 1 탄성 임피던스를 갖으며, 탄성 파장의 0.12 내지 0.13 배의 두께를 갖는 실리콘산화막과 상기 제 1 탄성 임피던스보다 큰 제 2 탄성 임피던스를 갖으며, 탄성 파장의 0.2 내지 0.3 배의 두께를 갖는 텅스텐(W)막이 번갈아 척층되어 있으며, 최상부층은 상기 실리콘산화막으로 이루어져 전체적으로 홀수층을 이루는 탄성 반사층; 상기 탄성 반사층에 형성된 바텀전극; 상기 바텀전극상에 형성되며 상기 전체 탄성 반사층의 0.45 내지 0.55 배의 두께인 압전박막; 및 상기 압전박막상에 형성된 탑전극을 구비하여 이루어진다.An acoustic wave device manufactured by the method for manufacturing the acoustic wave device of the present invention for achieving the above object is a substrate; Tungsten having a first elastic impedance, a silicon oxide film having a thickness of 0.12 to 0.13 times the elastic wavelength, a second elastic impedance greater than the first elastic impedance, and having a thickness of 0.2 to 0.3 times the elastic wavelength. W) the film is alternately chucked layer, the uppermost layer is made of the silicon oxide film, the elastic reflective layer forming an odd layer as a whole; A bottom electrode formed on the elastic reflective layer; A piezoelectric thin film formed on the bottom electrode and having a thickness of 0.45 to 0.55 times the total elastic reflection layer; And a top electrode formed on the piezoelectric thin film.
상기 바텀전극을 이루는 박막은 금(Au)막, 알루미늄(Al)막, 텅스텐(W)막 및 인듐(In)막중에서 어느 하나일 수 있으며, 상기 탑전극을 이루는 박막은 금(Au)막, 알루미늄(Al)막 및 텅스텐(W)막중에서 어느 하나일 수 있으며, 상기 압전물질은 아연산화막(ZnO) 또는 알루미늄나이트라이드막(AlN)인 것이 바람직하다.The thin film forming the bottom electrode may be any one of a gold (Au) film, an aluminum (Al) film, a tungsten (W) film, and an indium (In) film. The thin film forming the top electrode may be a gold (Au) film, It may be any one of an aluminum (Al) film and a tungsten (W) film, and the piezoelectric material is preferably a zinc oxide film (ZnO) or an aluminum nitride film (AlN).
상기 바텀전극이 금막인 경우는 상기 탄성 반사층과 상기 바텀전극사이에 티타늄(Ti)막, 크롬(Cr)막 및 니켈크롬(NiCr)막중에서 어느 하나의 버퍼막, 상기 바텀전극과 압전물질 사이 및 상기 압전물질과 탑전극 사이에는 외부 온도 변화로부터 소자의 공진 주파수 변동을 방지하기 위한 보호막으로 실리콘산화막(SiO2)이 더 형성되어 있는 것이 바람직하다.When the bottom electrode is a gold film, any one of a titanium (Ti) film, a chromium (Cr) film, and a nickel chromium (NiCr) film between the elastic reflective layer and the bottom electrode, between the bottom electrode and the piezoelectric material, and It is preferable that a silicon oxide film (SiO 2 ) is further formed between the piezoelectric material and the top electrode as a protective film to prevent resonance frequency variation of the device from external temperature change.
이하, 본 발명의 구체적인 일 실시예를 첨부한 도면을 참조하여 상세히 설명한다.Hereinafter, with reference to the accompanying drawings a specific embodiment of the present invention will be described in detail.
도1 내지 도5는 본 발명에 의한 탄성파 소자의 제조방법을 설명하기 위한 공정단면도들이다.1 to 5 are process cross-sectional views illustrating a method of manufacturing an acoustic wave device according to the present invention.
도1을 참조하면, 먼저 실리콘 기판(2)상에 제 1 탄성 임피던스를 갖는 실리콘산화막(4)과 제 2 탄성 임피던스를 갖는 텅스텐막(6)의 순서로 층착한다. 즉, 상기 실리콘산화막(4)과 상기 텅스텐막(6)이 순차적으로 한 쌍(Pair)을 이루도록 증착하며, 최상층은 상기 실리콘산화막(4)을 증착하여 전체적으로 홀수층을 갖는 탄성 반사층(7)를 형성한다. 여기서 탄성 임피던스는 상기 텅스텐막(6)이 더 크다.Referring to FIG. 1, first, a silicon oxide film 4 having a first elastic impedance and a tungsten film 6 having a second elastic impedance are deposited on the silicon substrate 2 in this order. That is, the silicon oxide film 4 and the tungsten film 6 are deposited in a pair in order, and the uppermost layer is formed by depositing the silicon oxide film 4 to form an elastic reflective layer 7 having an odd layer as a whole. Form. In this case, the elastic impedance of the tungsten film 6 is larger.
이때 상기 기판은 본 실시예에와 같이 실리콘 기판(2)에만 한정되는 것을 아니며 갈륨비소(GaAs), 유리(Glass), 석영(Quartz) 및 사파이어(Sapphire) 등 다양한 재질의 기판을 사용할 수 있다.In this case, the substrate is not limited to the silicon substrate 2 as in the present embodiment, and substrates of various materials such as gallium arsenide (GaAs), glass, quartz, sapphire, and the like may be used.
상기 실리콘산화막(4)과 텅스텐막(6)의 증착은 알에프 마그네트론 스퍼터링(Radio Frequency Magnetron Sputtering)방법을 사용한다. 상기 실리콘산화막(4)과 텅스텐막(6)의 공정조건은 각각 알에프 인가전력은 100 W, 60 W이며, 공정챔버의 진공도는 20 mtorr로 동일하다. 물론 화학기상증착방법(Chemical Vapour Deposition)으로 형성할 수 있다.The deposition of the silicon oxide film 4 and the tungsten film 6 uses an RF magnetron sputtering method. The process conditions of the silicon oxide film 4 and the tungsten film 6 are 100W and 60W, respectively, and the vacuum degree of the process chamber is equal to 20 mtorr. Of course, it can be formed by chemical vapor deposition (Chemical Vapor Deposition).
상기 탄성 반사층(7)은 소자 특성에 따라 반복해서 증착하여 7층 내지 11층으로 다양하게 형성할 수 있다. 본 실시예서는 7층구조의 탄성 반사층(7)을 형성한다.The elastic reflective layer 7 may be repeatedly formed according to device characteristics, and may be variously formed in 7 to 11 layers. In this embodiment, the elastic reflective layer 7 having a seven-layer structure is formed.
상기 실리콘산화막(4)의 두께(t1)는 탄성표면파의 탄성파장을 λ라고 하면 (λ×0.125)(t1) = (v0×0.25)/(f0×√ε)의 관계를 만족하도록 한다. 상기 텅스텐막(6)의 두께(t2)는 탄성표면파의 파장을 λ라고 하면 (λ×0.25)(t2) = (v0×0.25)/f0의 관계를 만족하도록 한다. 여기서 상기 v0는 박막의 탄성속도이며, f0는 탄성파 소자의 중심 대역 주파수 및 상기 ε는 그 물질의 유전율을 나타낸다. 여기서 상기 실리콘산화막(4)의 유전율은 3.8 이다.The thickness t 1 of the silicon oxide film 4 satisfies the relationship of (λ × 0.125) (t 1 ) = (v 0 × 0.25) / (f 0 × √ε) when the elastic wavelength of the surface acoustic wave is λ. Do it. The thickness t 2 of the tungsten film 6 satisfies the relationship of (λ × 0.25) (t 2 ) = (v 0 × 0.25) / f 0 when the wavelength of the surface acoustic wave is λ. Where v 0 is the elastic velocity of the thin film, f 0 is the center band frequency of the acoustic wave element, and ε represents the dielectric constant of the material. Here, the dielectric constant of the silicon oxide film 4 is 3.8.
일반적으로 상기 실리콘산화막(4)의 탄성속도는 5970 m/sec 이며, 상기 텅스텐막(6)의 탄성속도는 5180 m/sec 이다. 따라서, 원하는 중심 대역 주파수가 1GHz인 탄성파 소자를 구성하는 경우, 상기 실리콘산화막(4)과 텅스텐막(6)의 두께는 상기 식에 의하면 각각 약 1529 ㎚(t1)과 1295 ㎚(t2)일 수 있다.In general, the elastic velocity of the silicon oxide film 4 is 5970 m / sec, and the elastic velocity of the tungsten film 6 is 5180 m / sec. Therefore, in the case of forming an acoustic wave element having a desired center band frequency of 1 GHz, the thicknesses of the silicon oxide film 4 and the tungsten film 6 are about 1529 nm (t 1 ) and 1295 nm (t 2 ), respectively, according to the above formulas. Can be.
도2를 참조하면, 상기 실리콘산화막(4)상에 버퍼막(8)으로 티타늄막(Ti)을 100 내지 200Å 증착하고, 바텀전극(Bottom Electrode : 10)을 형성하기 위한 금막(Au)막을 1200 내지 1300Å 증착하고, 사진식각공정을 수행하여 소정의 바텀전극(10)을 형성한다. 상기 티타늄막(Ti) 및 알루미늄(Al)막의 증착은 알에프 마그네트론 스퍼터링방법 또는 증발증착(Evaporation Deposition)방법을 이용한다. 여기서 상기 티타늄막과 금막의 총 두께는 1500Å 미만으로 한다.Referring to FIG. 2, a gold film (Au) film for forming a bottom electrode (Bottom Electrode: 10) is formed by depositing a titanium film (Ti) from 100 to 200 Å with a buffer film (8) on the silicon oxide film (4). 1300 Å to 1300 Å deposited and a photolithography process are performed to form a predetermined bottom electrode 10. The titanium film Ti and aluminum film is deposited using an RF magnetron sputtering method or an evaporation deposition method. Here, the total thickness of the titanium film and the gold film is less than 1500 kPa.
또한 상기 버퍼막(8)으로는 크롬막(Cr) 또는 니켈크롬(NiCr)막을 사용할 수 있으며, 상기 바텀전극(10)으로는 상기 금막(Au) 이외에 알루미늄막, 텅스텐막(W), 은막(Ag) 및 인듐막(In)중에서 어느 하나를 사용할 수 있으며, 상기 인듐막을 바텀전극(10)으로 사용할 때는 상기 인듐막 자체도 탄성 반사층의 기능을 한다. 따라서 상기 인듐막의 두께는 탄성 파장의 0.25배를 갖도록한다.In addition, a chromium film (Cr) or a nickel chromium (NiCr) film may be used as the buffer film 8, and as the bottom electrode 10, in addition to the gold film Au, an aluminum film, a tungsten film W, and a silver film ( Any one of Ag) and an indium film (In) can be used. When the indium film is used as the bottom electrode 10, the indium film itself also functions as an elastic reflection layer. Therefore, the thickness of the indium film is 0.25 times the elastic wavelength.
상기 버퍼막(8)은 상기 실리콘산화막(4)과 바텀전극(10)으로 사용되는 금막과의 접착력을 향상시켜준다.The buffer film 8 improves the adhesion between the silicon oxide film 4 and the gold film used as the bottom electrode 10.
도3을 참조하면, 상기 바텀전극(10)상에 외부온도 변화로부터 소자의 공진 주파수 변동을 방지하기 위한 보호막(12)으로 실리콘산화막(12)을 1800 내지 2200Å 형성하고, 상기 실리콘산화막(12)상에 압전박막인 아연산화막(14)을 형성한다. 상기 실리콘산화막(12) 및 아연산화막(14)의 증착은 알에프 마그네트론 스퍼터링방법을 이용한다.Referring to FIG. 3, a silicon oxide film 12 is formed on the bottom electrode 10 as a protective film 12 to prevent resonance frequency variation of the device from a change in external temperature, and the silicon oxide film 12 is formed. A zinc oxide film 14 that is a piezoelectric thin film is formed on the film. The deposition of the silicon oxide film 12 and the zinc oxide film 14 uses an RF magnetron sputtering method.
상기 아연산화막(14)의 두께는 소자특성에 따라 다르며 본 발명에서는 상기 탄성 반사층(7) 전체 두께의 0.5가 되도록 한다. 따라서, 소자의 중심 대역 주파수(f0) 대역을 1GHz라고 할 때 상술한 상기 실리콘산화막(4)과 텅스텐막(6)의 두께에 의해 상기 아연산화막(14)의 두께는 약 10000㎚ 일 수 있다.The thickness of the zinc oxide film 14 varies depending on device characteristics, and in the present invention, the thickness of the elastic reflective layer 7 is 0.5. Accordingly, when the center band frequency f 0 of the device is 1 GHz, the thickness of the zinc oxide film 14 may be about 10000 nm due to the thicknesses of the silicon oxide film 4 and the tungsten film 6. .
도4를 참조하면, 상기 아연산화막(14)상에 도3에서와 동일하게 소자가 외부온도 변화로부터 공진 주파수 변동을 방지하기 위한 보호막(16)으로 실리콘산화막을 1800 내지 2200Å 형성하고, 상기 실리콘산화막의 보호막(16)상에 버퍼막(18)으로 티타늄막을 100 내지 200Å 증착한다.Referring to FIG. 4, a silicon oxide film is formed on the zinc oxide film 14 as a protective film 16 to prevent resonance frequency fluctuations from external temperature changes, as in FIG. 3, and the silicon oxide film is formed on the zinc oxide film 14. 100 to 200 Å of titanium film is deposited on the protective film 16 by the buffer film 18.
도5를 참조하면, 상기 버퍼막(18)상에 탑전극(Top Electrode)을 형성하기 위한 금막을 1000 내지 1300Å 증착한 후, 사진식각공정을 수행하여 소정의 탑전극(20)을 형성하여 탄성파 소자를 완성한다. 상기 탑전극(20)의 박막은 상기 금막 이외에 알루미늄막, 금막 또는 텅스텐막일 수 있다.Referring to FIG. 5, after depositing a gold film for forming a top electrode on the buffer film 18, 1000 to 1300 Å is deposited, a photolithography process is performed to form a predetermined top electrode 20 to form a seismic wave. Complete the device. The thin film of the top electrode 20 may be an aluminum film, a gold film, or a tungsten film in addition to the gold film.
상술한 바와 같이 본 발명은 기판상에 상대적으로 탄성 임피던스가 작은 실리콘산화막과 상대적으로 탄성 임피던스가 큰 텅스텐막을 각각 순차적으로 반복 적층하고, 또한 상기 압전물질을 상기 탄성 반사층 전체 두께의 약 0.5배로 형성하am로서 탄성파 에너지가 효과적으로 전극층사이에 모이도록 하여 공진이 효율적으로 발생토록한다. 그러므로 종래의 인터지디털 변환기(IDT : Inter Digital Transducer)의 미세형성보다는 기판상의 브레그 반사층의 두께를 조정함으로서 원하는 중심 대역 주파수를 얻을 수 있다.As described above, according to the present invention, a silicon oxide film having a relatively small elastic impedance and a tungsten film having a large elastic impedance are sequentially repeatedly stacked on the substrate, and the piezoelectric material is formed at about 0.5 times the total thickness of the elastic reflective layer. As am, the seismic wave energy is effectively collected between the electrode layers so that resonance occurs efficiently. Therefore, the desired center band frequency can be obtained by adjusting the thickness of the Bragg reflective layer on the substrate, rather than the microforming of a conventional Inter Digital Transducer (IDT).
따라서, 기판의 종류를 다양하게 사용할 수 있으며, 높은 전기적 반사계수(Q)를 갖으며, 대량생산 및 공정시간을 단축할 수 있는 효과가 있다.Therefore, it is possible to use a variety of substrates, have a high electrical reflection coefficient (Q), there is an effect that can reduce the mass production and processing time.
이상에서 본 발명은 기재된 구체예에 대해서만 상세히 설명되었지만 본 발명의 기술사상 범위 내에서 다양한 변형 및 수정이 가능함은 당업자에게 있어서 명백한 것이며, 이러한 변형 및 수정이 첨부된 특허청구범위에 속함은 당연한 것이다.Although the present invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical scope of the present invention, and such modifications and modifications are within the scope of the appended claims.
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| KR20020029882A (en) * | 2002-03-02 | 2002-04-20 | 주식회사 에이엔티 | The method of aoustic wave device fabrication using lcmp |
| KR100483340B1 (en) * | 2002-10-22 | 2005-04-15 | 쌍신전자통신주식회사 | Bulk Acoustic Wave Device and Process of The Same |
| KR100847528B1 (en) * | 2007-02-05 | 2008-07-22 | 성균관대학교산학협력단 | Film bulk acoustic resonator and method for fabricating the same |
| KR100857935B1 (en) * | 2006-02-24 | 2008-09-09 | 인피니언 테크놀로지스 아게 | Method of manufacturing an acoustic mirror for a piezoelectric resonator and method of manufacturing a piezoelectric resonator |
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1999
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| Publication number | Priority date | Publication date | Assignee | Title |
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| KR20020029882A (en) * | 2002-03-02 | 2002-04-20 | 주식회사 에이엔티 | The method of aoustic wave device fabrication using lcmp |
| KR100483340B1 (en) * | 2002-10-22 | 2005-04-15 | 쌍신전자통신주식회사 | Bulk Acoustic Wave Device and Process of The Same |
| KR100857935B1 (en) * | 2006-02-24 | 2008-09-09 | 인피니언 테크놀로지스 아게 | Method of manufacturing an acoustic mirror for a piezoelectric resonator and method of manufacturing a piezoelectric resonator |
| KR100847528B1 (en) * | 2007-02-05 | 2008-07-22 | 성균관대학교산학협력단 | Film bulk acoustic resonator and method for fabricating the same |
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