Detection of nanoscale ESD effect on GMR head signal using the wavelet transform technique: HBM and CDM cases

作者：Suwannata N; Rakpongsiri R; Sompongse D; Siritaratiwat A^*

来源：Journal of Electrostatics, 2009, 67(4): 583-589.

DOI：10.1016/j.elstat.2008.12.021

• ESD
• Wavelet transform
• GMR head
• Glitch

An electrical signal anomaly is an undesired signal and is difficult to detect by a commercial instrument due to its short duration and unpredictable fault on a signal. Since a GMR recording head is a stack of nanometer thick multilayers, in particular, a magnetic layer and conductor layers, for magnetic insulating spacers, it is very sensitive to electron movements. Visible damage is understandable and protectable but latent failure cannot be measured. It is possibly observed by using frequency-domain apparatus but certainly it is not real-time detection. Therefore, in order to detect a latent failure head affected by ESD in the time domain, current conventional instruments are ineffective. In this study, the wavelet transform technique using the 4th order Daubechies is proposed to detect the glitches on a magnetic recording head signal in the time domain. It is found that the glitches occur when the ESD level of the charged device model (CDM) and human body model (HBM) on giant magneto resistive (GMR) heads are in ranges of 6-15 V and 40-120 V, respectively. The electrical test parameters and scanning electron microscope (SEM) photo of the recording heads show no visible change in reader sensor. To ensure the results, the GMR damage is observed by SEM when the CDM-ESD and HBM-ESD are 10 V and 130 V, respectively. The glitches in the magnetic response signal of the GMR head are found to increase when the ESD level is increased. Thus, the Daubechies wavelet transform technique can be a novel approach to detect the pre-degradation of a GMR head due to an ESD effect.

• 出版日期2009-7