New Developments in IR Lock-in Thermography
New Developments in IR Lock-in Thermography
复制标题
红外锁定热成像技术的新进展
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
M. Gradhand
中科院分区：
文献类型：
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作者：
O. Breitenstein;J. Rakotoniaina;M. A. Rifai;M. Gradhand
基于红外（IR）相机的锁相热成像已被证明是集成电路（IC）故障分析的有用工具[1，2]。该技术基于向IC施加在3 Hz至1 kHz范围内周期性脉冲的电源电压。任何损耗电能的故障都会导致局部热源周期性振荡，从而导致表面的周期性温度（T-）调制。这些热源由IR相机成像，其输出数字在线锁定处理以产生局部T调制的幅度和相位。这种交流的灵敏度。由于其平均性质和对稳态IR图像的抑制，该技术可以比任何其他直接热成像技术好得多。然而，T调制幅度图像由IR发射率对比度调制，这可能使图像的解释复杂化。然而，这可以通过显示相位图像来避免[1，2]。因此，锁相热成像技术有可能大大扩展热失效分析的应用领域。本文将介绍锁相热成像技术的四项新进展。这些发展是（1）用胶体铋使IC表面变黑，（2）允许使用更高锁定频率的同步欠采样技术，（3）将0°/-90°信号显示为新的高分辨率发射率校正图像类型，以及（4）通过对0°/-90°信号进行数学解卷积来消除热模糊效应。用一个正常工作的运算放大器（μ A741）和一个损坏的电容作为测试器件，证明了这些技术的效果。它将被证明，黑化的IC表面提高了金属化区域的检测灵敏度高达10倍，而其他方法允许提高的有效空间分辨率。我们还将讨论哪种空间分辨率改进技术在不同情况下是最合适的。方法和分析
Lock-in thermography based on an infrared (IR) camera has proven to be a useful tool for failure analysis of integrated circuits (ICs) [1, 2]. This technique is based on the application of a supply voltage to the IC which is periodically pulsed in the 3 Hz to 1 kHz range. Any faults dissipating electrical energy lead to periodically oscillating local heat sources, which cause a periodic temperature (T-) modulation at the surface. These heat sources are imaged by the IR camera with its output digitally on line lock-in processed to yield the amplitude and phase of the local T-modulation. The sensitivity of this a.c. technique can be considerably better than that of any other direct thermal imaging technique due to its averaging nature and suppression of the steady-state IR image. Nevertheless, the T-modulation amplitude images are modulated by the IR emissivity contrast, which may complicate the interpretation of the images. However, this can be avoided by displaying the phase image [1, 2]. Thus, lock-in thermography has the potential to considerably expand the application field of thermal failure analysis. In this contribution four new technical developments of lock-in thermography will be introduced. These developments are (1) blackening the IC surface with colloidal bismuth, (2) the synchronous undersampling technique allowing the use of higher lock-in frequencies, (3) displaying the 0°/-90° signal as a novel high resolution emissivity corrected image type, and (4) removing the thermal blurring effect by mathematically deconvoluting the 0°/-90° signal. The effect of these techniques is demonstrated by using a regularly working operational amplifier (μA 741) and a damaged capacitor as test devices. It will be shown that blackening the IC surface improves the detection sensitivity in metallized regions by up to a factor of 10, whereas the other methods allow improvement of the effective spatial resolution. We will also discuss which of the spatial resolution improvement techniques is most appropriate in different situations. Methods and Analysis