WO2018120851A1 - 一种钽酸锂晶体基片的黑化处理方法 - Google Patents

一种钽酸锂晶体基片的黑化处理方法 Download PDF

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Publication number
WO2018120851A1
WO2018120851A1 PCT/CN2017/097847 CN2017097847W WO2018120851A1 WO 2018120851 A1 WO2018120851 A1 WO 2018120851A1 CN 2017097847 W CN2017097847 W CN 2017097847W WO 2018120851 A1 WO2018120851 A1 WO 2018120851A1
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WIPO (PCT)
Prior art keywords
crystal substrate
lithium niobate
niobate crystal
treatment method
blackening treatment
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PCT/CN2017/097847
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English (en)
French (fr)
Inventor
陈铭欣
刘明章
林飞
吴柯宏
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福建晶安光电有限公司
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Application filed by 福建晶安光电有限公司 filed Critical 福建晶安光电有限公司
Publication of WO2018120851A1 publication Critical patent/WO2018120851A1/zh
Priority to US16/452,037 priority Critical patent/US10862447B2/en
Priority to US17/099,535 priority patent/US11424730B2/en

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Classifications

    • 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
    • H10N30/8542—Alkali metal based oxides, e.g. lithium, sodium or potassium niobates
    • 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
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/16—Oxides
    • C30B29/22—Complex oxides
    • C30B29/30—Niobates; Vanadates; Tantalates
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B33/00—After-treatment of single crystals or homogeneous polycrystalline material with defined structure
    • 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
    • H03H9/02559—Characteristics of substrate, e.g. cutting angles of lithium niobate or lithium-tantalate substrates
    • 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
    • H03H9/02614—Treatment of substrates, e.g. curved, spherical, cylindrical substrates ensuring closed round-about circuits for the acoustical waves
    • H03H9/02622—Treatment of substrates, e.g. curved, spherical, cylindrical substrates ensuring closed round-about circuits for the acoustical waves of the surface, including back surface
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/64—Filters using surface acoustic waves

Definitions

  • the present invention relates to a method for fabricating a lithium niobate crystal, which is used on a wafer such as an elastic surface acoustic wave filter device, and uses a photolithography process to fabricate a metal interdigital electrode pattern to process a high frequency simulation of a mobile phone. Signal signal application.
  • Lithium niobate (LT) crystals are ferroelectrics having a melting point of about 1650 ° C and a Curie temperature of about 600 to 610 ° C.
  • the main purpose of the LT substrate is as a surface acoustic wave (SAW) filter material for high-frequency signal processing of mobile phones.
  • SAW surface acoustic wave
  • LT substrate has two major problems in the fabrication of SAW filter devices, which will lead to a decrease in device yield and increase. Cost of production.
  • the chip of the LT crystal is subjected to reduction treatment to reduce the volume resistivity thereof, and the LT chip is changed from white or light yellow to colored opaque during the reduction process, and the colored opaque LT substrate
  • the invention can effectively suppress the problem that the resolution of the pattern is lowered by the high light transmittance, and the conductivity of the chip is also obviously improved to reduce the pyroelectric effect, and the problem that the chip is cracked or the metal finger electrode is burned due to the electrostatic field can be avoided.
  • this reduction process is also called "blackening".
  • the Chinese invention application CN1754014A Japan Shin-Etsu Corporation proposes a method of reducing the blackening of the lithium niobate crystal substrate and the lithium niobate crystal substrate to be treated, and the reducing gas to be circulated Or a high-temperature deep reduction treatment of the lithium niobate crystal substrate to be treated in an inert gas to obtain a blackened lithium niobate crystal substrate, which requires a high-priced lithium niobate crystal substrate to be blackened after being subjected to high temperature.
  • the clips need to be ground for the crystal chip, which requires high flatness. It is difficult to ensure that the two chips can be closely attached. Therefore, the secondary reduction method is also adopted, resulting in complicated process, long process time, and processing. Ben Gao.
  • the Chinese invention application CN1856597A the Japanese Sumitomo Corporation's invention application in China publicly burying the powder reduction technology, mainly using a single strong reducing agent or a mixture of elemental and compound mixed reducing agents A1 and A1203, in the flow of N2, H2 A blackened lithium niobate crystal substrate is obtained by performing a reduction heat treatment in a gas atmosphere such as CO.
  • This metal powder reduction process has certain difficulty in adjusting the proportion and uniformity of the mixed powder, and has a certain degree of influence on human health in the preparation of the mixed powder.
  • the object of the present invention is to provide a blackening treatment method for a lithium niobate crystal substrate, and solve the problems that the processing technology of the company is difficult to control and the safety hazard of Sumitomo Corporation.
  • a blackening treatment method for a lithium niobate crystal substrate wherein the surface of one or both of the metal piece and the lithium niobate crystal substrate is roughened, and then placed below In the reducing environment of the temperature, the lithium niobate crystal substrate is subjected to reduction treatment by alternately stacking in a contact manner.
  • the reaction gas required in the blackening process can be more easily entered into the stacked materials, and the uniformity of blackening of the substrate can be improved.
  • the metal piece has a thickness of 0.05 to 20 mm.
  • composition of the metal piece includes one of Al, Ti, Zn, Fe or two or more of these metals.
  • the metal sheet, the lithium niobate crystal substrate or both are surface roughened by a chemical etching process.
  • the surface roughness Ra of the metal piece or the lithium niobate crystal substrate is between 0.1 um and 10 um.
  • the reducing environment contains any one of hydrogen, carbon monoxide, and nitrous oxide or a combination of any two or more of them.
  • step by step [0017] Further step by step [0017] Further, the chemical etching is a wet etching.
  • the wet etching is performed using hydrofluoric acid, nitric acid or a mixture of the two.
  • the wet etching temperature is between 20 and 80 ° C.
  • the wet etching of the lithium niobate crystal substrate is 3 to 10 hours.
  • the wet etching of the metal sheet is 3 to 10 minutes.
  • the technical effect of the present invention is that the lithium niobate crystal substrate can reduce the volume resistivity by the reduction treatment, and can improve the pyroelectric effect caused by the temperature difference in the manufacturing process of the surface acoustic wave filter (SAW filter).
  • SAW filter surface acoustic wave filter
  • a 4-inch LT crystal substrate crystal for a surface acoustic wave filter having a volume resistivity of 1*E10 to 1*E12 Qcm can be obtained.
  • the LT crystal substrate resistivity control by the blackening treatment of the invention is easy, the piezoelectric material characteristics of the LT crystal substrate are maintained, and the finished substrate is colored and the transmittance of the chip can be adjusted by parameters to meet the requirements of the lithography process.
  • the reduction process of the invention is relatively simple, safe to operate, and suitable for industrial mass production.
  • 4 to 6 are schematic diagrams of a blackening treatment method of Embodiment 2;
  • Each reference numeral in the drawing indicates: 1 : metal piece, 11 : oxide film, 2: lithium niobate crystal substrate, 21 : damage layer Embodiments of the invention
  • the invention provides a blackening treatment method for a lithium niobate crystal substrate, which is characterized in that the metal sheet material is rich in earth and easy to obtain, and can improve the complexity of the process and the health hazard of the operator.
  • This embodiment provides a blackening treatment method for a lithium niobate crystal substrate.
  • the surface of the metal sheet 1 is roughened by wet etching, and the coarsening is performed by using hydrofluoric acid, nitric acid or a mixture of the two.
  • the method is performed by etching, the wet etching temperature is between 20 and 80 ° C, and the wet etching of the metal sheet is between 3 and 10 minutes.
  • the surface roughness Ra of the metal sheet 1 is 0.1 to 10 um. Referring to FIG. 1, the roughened metal sheet 1 and the lithium niobate crystal substrate 2 are alternately stacked in a contact manner in a cavity, wherein the material of the metal sheet 1 is stacked.
  • Al Ti, Zn or Fe may be used.
  • Al is preferably used in the material of the metal sheet 1.
  • the thickness D of the metal sheet 1 is 0.05 to 20 mm, and is placed in an environment lower than the Curie temperature to carry out the lithium niobate crystal substrate 2.
  • Restore processing Specifically, the blackening treatment environment temperature is 350 ⁇ 600 °C, and the processing time is 3 ⁇ 12 hours.
  • the blackening treatment introduces a flowing chemical reducing gas at a flow rate of 0.3 to 5.0 liters/min, and the chemical reducing gas component includes nitrogen, hydrogen, carbon monoxide, argon or a combination of any of them, and the reduction treatment is carried out in the furnace.
  • the pressure in the chamber during the blackening process is +3.0KPa ⁇ 20.0KPa.
  • the production cost is high because of the rare metal, and the production cost of the metal Al, Ti, Zn or Fe sheet can be greatly reduced.
  • the flowing reducing gas is used in the blackening process, so if the flatness of the chip is better, the reducing reaction gas is less likely to flow between the chips to lower the reduction reaction rate, and the roughened metal sheet 1 and the crucible
  • the lithium acid crystal substrate 2 is stacked, and the reducing gas is more easily flowed on the surface of the metal piece 1 and the lithium niobate crystal substrate 2 to accelerate the reduction reaction.
  • a dense oxide film 11 is easily formed on the surface of the metal piece 1, and the oxide film 11 belongs to a steady state and is not easily reacted with the lithium niobate crystal substrate 2.
  • this embodiment is roughened. The treatment can effectively remove the oxide film 11 on the surface of the metal sheet 1 to form a clean metal surface, thereby facilitating the reduction reaction between the metal and the lithium niobate chip.
  • This embodiment differs from the first embodiment in that the surface of the lithium niobate crystal substrate 2 is roughened, and the coarsening is carried out by wet etching using hydrofluoric acid, nitric acid or a mixture of the two.
  • the etching temperature is between 20 and 80 ° C
  • the wet etching of the metal sheet is 3 to 10 minutes
  • the wet etching of the lithium niobate crystal substrate is 3 to 10 hours.
  • the lithium niobate crystal substrate 2 has a surface roughness Ra of 0.1 to 10 ⁇ m. Referring to Fig. 4, the roughened lithium niobate crystal substrate 2 and the unroughened metal sheet 1 are stacked for reduction treatment.
  • the damaged layer 21 makes it difficult for the reducing gas to be reduced with the lithium niobate crystal substrate 2. reaction.
  • the damaged layer is removed by wet etching, and the surface of the lithium niobate crystal substrate 2 is further roughened to reduce the reducing gas and the non-damaged lithium niobate crystal substrate 2.
  • the blackening process is mostly performed after slicing.
  • the present embodiment proposes to respectively roughen the metal piece 1 and the lithium niobate crystal substrate 2, respectively.
  • Technical solution roughening using hydrofluoric acid, nitric acid or a mixture of the two is carried out by wet etching, the wet etching temperature is between 20 and 80 ° C, and the wet etching of the metal sheet is 3 to 10 Minutes, the wet etching of the lithium niobate crystal substrate is 3 to 10 hours.
  • the surface roughness Ra of the metal piece 1 and the lithium niobate crystal substrate 2 is 0. l ⁇ 10um.
  • the roughened metal sheet 1 and the lithium niobate crystal substrate 2 are alternately stacked in a contact manner in a cavity, wherein the material of the metal sheet 1 may be Al, Ti, Zn or Fe, metal sheet.
  • the thickness D of 1 is 0.05 to 20 m, and the lithium niobate crystal substrate 2 is subjected to reduction treatment in an environment lower than the Curie temperature.
  • the blackening treatment environment temperature is 350 ⁇ 600 °C, and the processing time is 3 ⁇ 12 hours.
  • the blackening treatment introduces a flowing chemical reducing gas at a flow rate of 0.3 to 5.0 liters/min, and the chemical reducing gas component includes nitrogen gas.
  • the reduction treatment is carried out in the furnace, and the pressure in the chamber during the blackening process is +3.0KPa ⁇ 20.0KPa.
  • the production cost is high because of the rare metal, and the production cost of the metal Al, Ti, Zn or Fe sheet can be greatly reduced.
  • A1 is preferably used as the metal sheet material.
  • the flowing reducing gas is used in the blackening process, so if the flatness of the lithium niobate crystal substrate 2 is better, the reducing reaction gas is less likely to flow between the chips to lower the reduction reaction rate, metal
  • the sheet 1 is coarsened with the lithium niobate crystal substrate 2 and then stacked, further promoting the flow of the reducing gas on the surface of the metal sheet 1 and the lithium niobate crystal substrate 2, and accelerating the reduction reaction.
  • the surface of the metal sheet 1 is likely to form a dense oxide film 11, which belongs to a steady state and is not easily reacted with the lithium niobate crystal substrate 2, and is roughened in this embodiment.
  • the oxide film 11 on the surface of the metal piece 1 can be effectively removed to form a clean metal surface for the metal and the lithium niobate crystal substrate to undergo a reduction reaction.
  • the surface damage layer 21 can be effectively removed by the roughening treatment, and the reducing gas is subjected to a reduction reaction with the non-damaged lithium niobate crystal substrate 2.
  • the lithium niobate crystal substrate is changed from white or light yellow to colored opaque, and the original piezoelectric material characteristics are maintained. After blackening, the lithium niobate crystal substrate 2 is darker in color, and its chip transmittance can be effectively reduced to meet the process requirements of the post-process lithography process.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Materials Engineering (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Metallurgy (AREA)
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  • Inorganic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
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Abstract

一种钽酸锂晶体基片的黑化处理方法，在化学还原气氛中，将金属片与钽酸锂晶体基片之表面进行粗化后以接触方式交替堆叠，置于低于居里温度的环境中，对钽酸锂晶体基片进行还原处理，使钽酸锂晶体基片由白色或淡黄色转变为有色不透明化，依然保持其原有之压电材料特性。钽酸锂晶体基片经还原处理可降低其体电阻率，可改善声表面波滤波器（SAW filter）制造过程中因温度差异引起热释电效应产生的放电现象，并提高叉指电极线条于光刻工艺的精度，有助于提升SAW器件制作的成品率降低生产成本。

Description

一种钽酸锂晶体基片的黑化处理方法
技术领域
[0001] 本发明涉及一种钽酸锂晶体的制造方法， 该钽酸锂晶体使用于弹性表面声波滤 波器件等晶圆上， 利用光刻工艺制作金属叉指电极图案而处理移动电话高频模 拟讯号信号的应用中。
背景技术
[0002] 钽酸锂 (LT)晶体是熔点约为 1650°C、 居里温度约为 600~610°C的铁电体。 而且
， LT基板的主要用途是作为移动电话的高频信号处理用的表面声波（SAW)滤波 器材料， 但是 LT基板于 SAW滤波器器件制作中出现两个主要问题， 将导致器件 成品率降低、 增加生产成本。 第一、 因 LT基板高的光透射率， 使得在 SAW器件 制造工序之一的光刻工序中光在基板背面反射并返回到表面， 产生降低所形成 图案的分辨率的问题。 第二、 因 LT晶体具有高的热释电系数， 容易受温度变化 差异产生在芯片表面积累大量的静电荷， 这些静电荷会在金属叉指电极间或芯 片间自发释放， 进而导致芯片幵裂或金属叉指电极烧毁等问题。
[0003] 因此， 为了解决上述问题， 将 LT晶体的芯片进行还原处理来降低其体电阻率， 此还原处理过程中 LT芯片由白色或淡黄色转变为有色不透明化， 此有色不透明 化的 LT基板能有效抑制高的光透射率解决图案的分辨率降低的问题， 同吋也明 显提高芯片导电率藉以降低热释电效应， 可以避免静电场产生造成芯片幵裂或 金属叉指电极烧毁等问题。 通常 LT芯片还原后其表面会呈现灰色或黑色， 故也 将此还原处理过程称作"黑化"。
[0004] 例如中国发明申请 CN1754014A, 日本信越公司提出将黑化后的钽酸锂晶体基 片与待处理的钽酸锂晶体基片交替层迭进行还原处理的方法,需在流通的还原性 气体或惰性气体中对待处理的钽酸锂晶体基片进行高温深度还原处理后获得黑 化钽酸锂晶体基片， 此种工艺需要以高单价钽酸锂晶体基片先经高温制作成黑 化后的夹片， 且对晶芯片需研磨加工， 对平整度要求高， 因难以保证两种芯片 能紧密贴合， 故还要采用二次还原方式， 导致工艺复杂、 制程吋间长、 处理成 本高。
[0005] 又例如中国发明申请 CN1856597A, 日本住友公司在中国的发明申请公幵了埋 粉还原技术,主要采用单质强还原剂或者单质与化合物混合还原剂 A1和 A1203混 合粉末， 在流动 N2， H2、 CO等气体气氛中进行还原热处理后获得黑化钽酸锂晶 体基片。 此种金属粉末还原工艺对于混合粉末调节比例及均匀性控制具有一定 的难度,且调制混合粉末作业中对人体健康有一定程度的影响。
技术问题
问题的解决方案
技术解决方案
[0006] 本发明的目的在于： 提供一种钽酸锂晶体基片的黑化处理方法， 同吋解决信越 公司工艺复杂和的住友公司工艺条件不易调控和安全隐患等问题。
[0007] 根据本发明， 提供一种钽酸锂晶体基片的黑化处理方法， 将金属片与钽酸锂晶 体基片其中一项或者两项之表面进行粗化后， 置于低于居里温度的还原性环境 中， 以接触方式交替堆叠， 对钽酸锂晶体基片进行还原处理。 通过此方法可让 黑化过程中所需要的反应气体更容易进入到堆叠的材料中， 提升基片黑化的均 匀性。
[0008] 进一步地， 所述金属片的厚度为 0.05~20mm。
[0009] 进一步地， 所述金属片的成分包括 Al， Ti， Zn， Fe其中之一或者这些金属中两 种以上共同构成。
[0010] 进一步地， 金属片、 钽酸锂晶体基片或两者都通过化学蚀刻工艺进行表面粗化
[0011] 进一步地， 所述金属片或钽酸锂晶体基片的表面粗糙度 Ra介于 0.1 um~10um。
[0012] 进一步地， 所述还原性环境含有氢气、 一氧化碳、 一氧化二氮中任意一种气体 或其中任意两种以上气体组合。
[0013] 进- 步地
[0014] 进- 步地
[0015] 进- 步地
[0016] 进- 步地 [0017] 进- 步地， 所述化学蚀刻为湿法蚀刻。
[0018] 进- 步地， 所述湿法蚀刻使用氢氟酸、 硝酸或两者之混合液进行。
[0019] 进- 步地， 所述湿法蚀刻温度介于摄氏 20~80°C。
[0020] 进- 步地， 所述钽酸锂晶体基片的湿法蚀刻吋间为 3~10小吋。
[0021] 进- 步地， 所述金属片的湿法蚀刻吋间为 3~10分钟。
发明的有益效果
有益效果
[0022] 本发明的技术效果在于， 钽酸锂晶体基片经还原处理可降低其体电阻率， 可改 善声表面波滤波器 （SAW filter) 制造过程中因温度差异引起热释电效应产生的 放电现象， 并提高叉指电极线条于光刻工艺的精度， 有助于提升 SAW器件制作 的成品率降低生产成本。 通过本发明可以得到体电阻率为 1*E10~1*E12 Qcm的 表面声波滤波器用 4寸 LT晶体基片晶。 采用本发明黑化处理 LT晶体基片电阻率控 制容易， 仍旧保持 LT晶体基片之压电材料特性且成品基片有色并可通过参数调 整芯片之穿透率， 以达到光刻制程的需求。 本发明的还原工艺相对简单， 操作 安全， 对适合工业量产。
[0023] 本发明的其它特征和优点将在随后的说明书中阐述， 并且， 部分地从说明书中 变得显而易见， 或者通过实施本发明而了解。 本发明的目的和其他优点可通过 在说明书、 权利要求书以及附图中所特别指出的结构来实现和获得。
对附图的简要说明
附图说明
[0024] 附图用来提供对本发明的进一步理解， 并且构成说明书的一部分， 与本发明的 实施例一起用于解释本发明， 并不构成对本发明的限制。 此外， 附图数据是描 述概要， 不是按比例绘制。
[0025] 图 1~3： 实施例 1的黑化处理方法示意图；
[0026] 图 4~6： 实施例 2的黑化处理方法示意图；
[0027] 图 7~8: 实施例 3的黑化处理方法示意图。
[0028] 图中各标号表示： 1 : 金属片， 11 : 氧化膜， 2: 钽酸锂晶体基片， 21 : 损伤层 本发明的实施方式
[0029] 为了能彻底地了解本发明， 将在下列的描述中提出详尽的步骤及其组成， 另外 ， 众所周知的组成或步骤并未描述于细节中， 以避免造成本发明不必要之限制 。 本发明的较佳实施例会详细描述如下， 然而除了这些详细描述之外， 本发明 还可以广泛地施行在其它的实施例中， 且本发明的范围不受限定， 以专利权利 范围为准。
[0030] 本发明提出一种钽酸锂晶体基片的黑化处理方法， 其选用金属片材料在地球蕴 藏量丰富且容易取得， 可改善工艺复杂度和操作者健康隐患等问题。
[0031] 实施例 1
[0032] 本实施例提供一种钽酸锂晶体基片的黑化处理方法， 采用湿法蚀刻将金属片 1 进行表面粗化， 粗化采用氢氟酸、 硝酸或两者之混和液以湿法蚀刻的方式进行 ， 所述湿法蚀刻温度介于摄氏 20~80°C， 金属片的湿法蚀刻吋间为 3~10分钟。 处 理后金属片 1的表面粗糙度 Ra为 0.1~10um， 参照图 1， 在腔体内将粗化后的金属 片 1与钽酸锂晶体基片 2以接触方式交替堆叠， 其中金属片 1的材料可以采用 Al、 Ti， Zn或 Fe， 金属片 1材料中优选采用 Al， 金属片 1的厚度 D为 0.05~20mm， 置于 低于居里温度的环境中， 对钽酸锂晶体基片 2进行还原处理。 具体来说， 黑化处 理吋环境温度为 350~600°C， 处理吋间为 3~12小吋。 黑化处理吋通入流动的化学 还原性气体， 流速为 0.3~5.0升 /分钟， 化学还原性气体成分包括氮气、 氢气、 一 氧化碳、 氩气或其中任意种气体组合， 还原处理在炉膛内进行， 黑化处理过程 中腔体内压强为 +3.0KPa~20.0KPa。 相比使用钽酸锂当处理片， 因钽为稀有金属 所以造成其生产成本高,而采用金属 Al， Ti， Zn或 Fe片生产成本可大幅降低。
[0033] 一方面， 黑化处理过程中使用流动的还原气体,所以若是芯片平坦度越好,将导 致还原反应气体不易在芯片间流动降低了还原反应速率， 粗化后的金属片 1与钽 酸锂晶体基片 2进行堆叠， 还原性气体在金属片 1和钽酸锂晶体基片 2表面更易流 动， 加速还原反应。
[0034] 另一方面， 参看图 2， 金属片 1表面容易生成一层致密的氧化膜 11， 氧化膜 11属 于一种稳态， 不易与钽酸锂晶体基片 2进行反应。 参看图 3， 本实施例通过粗化 处理能有效地将金属片 1表面的氧化膜 11脱除， 形成干净的金属表面， 以利于金 属与钽酸锂芯片进行还原反应。
[0035] 实施例 2
[0036] 本实施例与实施例 1的区别在于， 对钽酸锂晶体基片 2进行表面粗化， 粗化采用 氢氟酸、 硝酸或两者之混和液以湿法蚀刻的方式进行， 湿法蚀刻温度介于摄氏 2 0~80°C, 金属片的湿法蚀刻吋间为 3~10分钟， 钽酸锂晶体基片的湿法蚀刻吋间 为 3~10小吋。 处理后钽酸锂晶体基片 2的表面粗糙度 Ra为 0.1~10um， 参看图 4， 将粗化后的钽酸锂晶体基片 2与未粗化的金属片 1堆叠进行还原处理。
[0037] 比较现有技术将钽酸锂晶体基片研磨后， 获得较好的平坦度再进行还原反应， 粗化的钽酸锂晶体基片,其还原反应表现比研磨后来得好。 原因在于黑化处理过 程中使用还原气体,所以若是芯片平坦度越好,将导致还原反应气体不易在芯片间 流动进行加速还原反应。
[0038] 除上述原因外， 也因为钽酸锂晶体基片 2研磨后表面会有一层损伤层 21， 参看 图 5， 该损伤层 21使其还原气体不易与钽酸锂晶体基片 2进行还原反应。 参看图 6 ， 本实施例通过湿法蚀刻消除损伤层， 同吋进一步对钽酸锂晶体基片 2的表面粗 化， 使还原气体与无损伤的钽酸锂晶体基片 2进行还原反应。
[0039] 实施例 3
[0040] 根据现有技术， 目前黑化工艺大多数于切片后进行， 结合实施例 1和实施例 2， 本实施例提出分别对金属片 1和钽酸锂晶体基片 2分别进行粗化的技术方案， 粗 化采用氢氟酸、 硝酸或两者之混和液以湿法蚀刻的方式进行， 湿法蚀刻温度介 于摄氏 20~80°C， 金属片的湿法蚀刻吋间为 3~10分钟， 钽酸锂晶体基片的湿法蚀 刻吋间为 3~10小吋。 经过粗化后， 金属片 1和钽酸锂晶体基片 2表面粗糙度 Ra为 0. l〜10um。
[0041] 参看图 7， 在腔体内将粗化后的金属片 1与钽酸锂晶体基片 2以接触方式交替堆 叠， 其中金属片 1的材料可以采用 Al、 Ti， Zn或 Fe， 金属片 1的厚度 D为 0.05~20m m， 置于低于居里温度的环境中， 对钽酸锂晶体基片 2进行还原处理。 具体来说 ， 黑化处理吋环境温度为 350~600°C， 处理吋间为 3~12小吋。 黑化处理吋通入流 动的化学还原性气体， 流速为 0.3~5.0升 /分钟， 化学还原性气体成分包括氮气、 氢气、 一氧化碳、 氩气或其中任意种气体组合， 还原处理在炉膛内进行， 黑化 处理过程中腔体内压强为 +3.0KPa~20.0KPa。 相比使用钽酸锂当处理片， 因钽为 稀有金属所以造成其生产成本高,而采用金属 Al， Ti， Zn或 Fe片生产成本可大幅 降低， 本实施例优选采用 A1作为金属片材料。
[0042] 本实施例具有多方面的有益效果：
[0043] 有益效果之一： 黑化处理过程中使用流动的还原气体,所以若是钽酸锂晶体基片 2平坦度越好,将导致还原反应气体不易在芯片间流动降低了还原反应速率， 金属 片 1与钽酸锂晶体基片 2粗化后进行堆叠， 进一步促进了还原性气体在金属片 1和 钽酸锂晶体基片 2表面的流动， 加速还原反应。
[0044] 有益效果之二， 金属片 1表面容易生成一层致密的氧化膜 11， 氧化膜 11属于一 种稳态， 不易与钽酸锂晶体基片 2进行反应， 本实施例通过粗化处理能有效地将 金属片 1表面的氧化膜 11脱除， 形成干净的金属表面， 以利金属与钽酸锂晶体基 片进行还原反应。
[0045] 有益效果之三， 因钽酸锂晶体基片 2研磨后表面会有一层损伤层 21， 该损伤层 2 1使其还原气体不易与钽酸锂晶体基片 2进行还原反应， 本实施例通过粗化处理 能有效地将表面损伤层 21消除， 使还原性气体与无损伤的钽酸锂晶体基片 2进行 还原反应。
[0046] 参照图 8， 本实施例使钽酸锂晶体基片由白色或淡黄色转变为有色不透明化， 依然保持其原有之压电材料特性。 黑化后钽酸锂晶体基片 2颜色较深色， 其芯片 穿透率能有效降低， 满足后制程光刻工艺的制程要求。
[0047] 很明显地， 本发明的说明不应理解为仅仅限制在上述实施例， 而是包括利用本 发明构思的所有可能的实施方式。

Claims

权利要求书
一种钽酸锂晶体基片的黑化处理方法， 将金属片与钽酸锂晶体基片其 中一项或者两项之表面进行粗化后， 置于低于居里温度的还原性环境 中， 以接触方式交替堆叠， 对钽酸锂晶体基片进行还原处理。
根据权利要求 1所述的一种钽酸锂晶体基片的黑化处理方法， 其特征 在于： 所述金属片的厚度为 0.05~20mm。
根据权利要求 1所述的一种钽酸锂晶体基片的黑化处理方法， 其特征 在于： 所述金属片的成分包括 Al， Ti， Zn， Fe其中之一或者这些金属 中两种以上共同构成。
根据权利要求 1所述的一种钽酸锂晶体基片的黑化处理方法， 其特征 在于： 金属片、 钽酸锂晶体基片或两者都通过化学蚀刻工艺进行表面 粗化。
根据权利要求 1所述的一种钽酸锂晶体基片的黑化处理方法， 其特征 在于： 所述金属片或钽酸锂晶体基片的表面粗糙度 Ra介于 0.1 um〜10um。
根据权利要求 1所述的一种钽酸锂晶体基片的黑化处理方法， 其特征 在于： 所述还原性环境含有氢气、 一氧化碳、 一氧化二氮中任意一种 气体或其中任意两种以上气体组合。
根据权利要求 6所述的一种钽酸锂晶体基片的黑化处理方法， 其特征 在于： 所述气体为流动的， 流速为 0.3~5.0升 /分钟。
根据权利要求 1所述的一种钽酸锂晶体基片的黑化处理方法， 其特征 在于： 所述低于居里温度， 温度范围为 350~610°C。
根据权利要求 8所述的一种钽酸锂晶体基片的黑化处理方法， 其特征 在于： 所述还原处理的吋间为 3~12小吋。
根据权利要求 1所述的一种钽酸锂晶体基片的黑化处理方法， 其特征 在于： 所述还原处理在炉膛内进行， 炉膛内压强为 +3.0KPa~20KPa。 根据权利要求 4所述的一种钽酸锂晶体基片的黑化处理方法， 其特征 在于： 所述化学蚀刻为湿法蚀刻。
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