Development of a Method to Evaluate the Surface of Single Crystal Substrates for Super-High-Frequency SAW Devices by UMS Technology

利用 UMS 技术开发评估超高频 SAW 器件单晶衬底表面的方法

• 批准号: 12450119
• 负责人: KUSHIBIKI Jun-ichi
• 金额: $ 9.6万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12450119/
• 关键词: Ultrasonic microspectroscopy; LFB ultrasonic material characterization; Standard specimen; Damaged surface layer; Leaky surface acoustic wave; Evaluation of single crystal materials; Materials for SAW devices; Scanning nonlinear dielectric microsco

In this study, ultrasonic microspectroscopy (UMS) technology, using the line-focus-beam (LFB) and plane-wave ultrasonic material characterization system, has been applied to the problems associated with the homogeneities and modified/damaged surface layers of LiNbO_3 and LiTaO_3 single crystals for super-high-frequency (SHF) surface acoustic wave (SAW) devices. The purpose of this study was to establish the quantitative analysis and evaluation method using this technology.1. The relative and absolute accuracies for the propagation characteristics of leaky SAW (LSAW) measured by the LFB-UMC system have been improved.2. Chemical composition dependences of the acoustical physical constants of LiNbO_3 and LiTaO_3 single crystals were determined. This enables us to calculate the propagation characteristics of LSAW and SAW for the crystals with an arbitrary chemical composition.3. Experimental relationships (calibration lines) among the LSAW velocity, Curie temperature, lattice constants, et … More c., were obtained to evaluate each property of the crystals by a common scale of LSAW velocity.4. A method for improving the crystal growth conditions through the evaluation of the chemical composition distributions of commercially available LiTaO_3 single crystals was proposed and an extremely homogeneous crystal was successfully grown.5. For the demonstration of evaluating modified/damaged surface layers, we fabricated several LiTaO_3 substrates with protonexchanged layers and domain-inverted layers as model specimens. The thickness resolution of the surface layers estimated by LSAW velocity was nanometer order.6. The resolution of scanning nonlinear dielectric microscopy was improved with an atomic size.7. Center frequencies and SAW velocities were measured for 0.5, 1, and 2 GHz-band SAW filters fabricated on LiTaO_3 wafers whose distributions in chemical composition were preexamined by measuring LSAW velocities. The results exhibited that variations of the center frequencies and differences between the calculated and measured SAW velocities became larger as the frequency became higher. It was considered that problems associated with the damaged surface layers of the substrates were detected. Less

本研究利用线聚焦超声束（LFB）和平面波超声材料表征系统，应用超声显微光谱（UMS）技术研究了超高频声表面波（SAW）器件用LiNbO_3和LiTaO_3单晶的均匀性和表面改性/损伤问题。本研究的目的是建立利用该技术进行定量分析和评价的方法. LFB-UMC系统测量漏声表面波传播特性的相对和绝对精度得到了提高.测定了LiNbO_3和LiTaO_3单晶的声物理常数随化学成分的变化。这使我们能够计算的传播特性的LSAW和SAW的晶体与任意的化学成分. LSAW速度、居里温度、晶格常数等之间的实验关系（校准线） ...更多信息 c.将该混合物干燥，通过一个共同的尺度LSAW的速度获得评估的晶体的每一个属性。提出了一种通过评估市售LiTaO_3单晶的化学成分分布来改善晶体生长条件的方法，并成功地生长出了非常均匀的晶体.为了验证表面改性/损伤层的评估，我们制作了几个具有质子交换层和畴反转层的LiTaO_3衬底作为模型样品。由LSAW声速估算的表面层厚度分辨率为纳米量级.扫描非线性介电显微镜的分辨率随着原子尺度的增大而提高.本文测量了在LiTaO_3晶片上制作的0.5，1，2 GHz波段SAW滤波器的中心频率和SAW速度，并通过测量LSAW速度预先检查了LiTaO_3晶片的化学成分分布。结果表明，随着频率的升高，中心频率的变化以及声表面波速度的计算值与实测值之间的差异越来越大。据认为，检测到了与基底的受损表面层相关的问题。少

项目成果

T.Sakai, T.Watanabe, Y.Cho, K.Matsuura, H.Funakubo: "Characterization of Ferroelectric Property of C-Axis- and Non-C-Axis-Oriented Epitaxially Grown Bi_2Vo_<5.5> Thin Films"Jpn. J. Appl. Phys.. 40・11. 6481-6486 (2001)

T.Sakai、T.Watanabe、Y.Cho、K.Matsuura、H.Funakubo：“C 轴和非 C 轴取向外延生长 Bi_2Vo_<5.5> 薄膜的铁电特性表征”Jpn J。应用物理.. 40・11.

J.Kushibiki,T.Okuzawa,J.Hirohashi,and Y.Ohashi: "Line-Focus-Beam Acoustic Microscopy Characterization of Optical-Grade LiTaO_3 Single Crystals"J.Appl.Phys.. 87・9. 4395-4403 (2000)

J.Kushibiki、T.Okuzawa、J.Hirohashi 和 Y.Ohashi：“光学级 LiTaO_3 单晶的线聚焦声学显微镜表征”J.Appl.Phys.. 87・9（2000 年） ）

S.Kazuta,Y.Cho,H.Odagawa,and M.Kadota: "Determination of the Polarities of ZnO Thin Films on Polar and Nonpolar Substrates Using Scanning Nonlinear Dielectric Microscopy"Jpn.J.Appl.Phys.. 39・5B. 3121-3124 (2000)

S. Kazuta、Y. Cho、H. Odakawa 和 M. Kadota：“使用扫描非线性介电显微镜测定极性和非极性基材上 ZnO 薄膜的极性”Jpn.J.Appl.Phys.. 39・5B。 3121-3124 (2000)

H.Odagawa and Y.Cho: "Simultaneous Observation of Nano-Sized Ferroelectric Domains and Surface Morphology Using Scanning Nonlinear Dielectric Microscopy"Surface Science. 463・. L621-L625 (2000)

H.Odakawa 和 Y.Cho：“使用扫描非线性介电显微镜同时观察纳米尺寸的铁电畴和表面形态”表面科学 463·L625。

J.Kushibiki, M.Arakawa, R.Okabe: "High-Accuracy Standard Specimens for the Line-Focus-Beam Ultrasonic Material Characterization System"IEEE Trans. UFFC. 49. 827-835 (2002)

J.Kushibiki、M.Arakawa、R.Okabe：“线聚焦束超声波材料表征系统的高精度标准样本”IEEE Trans。