Young’s Modulus Detection for Ultra-Thin Film by LSAWs Technique with Wavelet and FIR Filter De-Noising
Young’s Modulus Detection for Ultra-Thin Film by LSAWs Technique with Wavelet and FIR Filter De-Noising
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DOI：
10.4028/www.scientific.net/amr.301-303.623
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发表时间：
2011-07
期刊：
影响因子：
--
通讯作者：
X. Shan;X. Xiao;Yuan Sun
中科院分区：
文献类型：
--
作者：
X. Shan;X. Xiao;Yuan Sun
激光表面声波(LSAWs)技术是一种测定薄膜杨氏模数的可行方法。从实验系统中检测到的原始声表面波(SAW)信号经常受到外界噪声的污染。提出了一种基于小波和FIR滤波的图像去噪新方法。小波阈值去噪是去除原始声表面波信号中高频噪声成分的关键，而FIR滤波器可以去除无用的低频噪声。检测信号的有效带宽范围为50~190 MHz。通过改进的最小二乘拟合法将实验色散曲线与理论计算的色散曲线进行匹配，即可得到被测样品的杨氏模数。测得四个低介电常数(Low-k)样品的杨氏模数分别为7.1、6.8、1.1和1.0 Gpa。
Laser-generated surface acoustic waves (LSAWs) technique is a feasible method to determine the Young’s modulus of thin films. The raw surface acoustic wave (SAW) signals detected from the experimental system are often contaminated by external noises. A novel de-noising method is proposed in this paper with wavelet and FIR filter. The wavelet threshold de-noising is essential to reduce the high frequency noise components in the raw SAW signals, while FIR filter can remove the useless low frequency noises. The useful bandwidth of the detected signal ranges from 50 to 190 MHz. Young’s modulus of the detected samples can be obtained by matching the experimental dispersive curves with the theoretical calculated ones via an improved least square fitting method. The Young’s moduli of four low dielectric constant (low-k) samples detected in the measurement are 7.1, 6.8, 1.1 and 1.0 GPa, respectively.