A new method for the hermeticity testing of wafer-level packaging

Abstract

Until now, the determination of microelectronic packages hermeticity has been related to the MIL-STD-883 method 1014 which is based on the helium leak detection method. But this method is no longer suited for small packages due to the resolution limit of the apparatus. Indeed, leaks induced by nonhermetic MEMS packages are often one order of magnitude smaller than the resolution of the helium leak tester. Consequently, characterization of MEMS packages requires new methodologies to measure hermeticity accurately. Two methods will be investigated in the context of this study: the membrane deflection measurement, when exposed to different pressures, using optical profilometry, and the measurement of the variation of gas concentration in a sealed silicon cavity by Fourier transform infrared spectroscopy (FTIR). The calculated leak rates are compared for samples where the standard fine leak test gave no results. The values obtained for the leak rates with the optical test and FTIR test for the same sample are identical, showing the relevance of these two methods. FTIR spectroscopy is a promising method which enhances standard detection limits. It can be used as a reliable process quality control tool.

Low-temperature indium-bonded alkali vapor cell for chip-scale atomic clocks

“…The first method was mechanical; it is based on the measure of the deflection of a Si membrane 24 integrated into dedicated cell samples. If the deflection is small compared to the size of the membrane, the membrane deflection can be linked to the pressure difference P D ¼ P ext À P between the two sides of the membrane.…”

Vacuum quality evaluation for uncooled micro bolometer thermal imager sensors

“…Standard methods of vacuum measurement like the helium leak test are not applicable for small volume packages [8,9] and rest gas analyses are destructive measurements. Other methods like measuring the vacuum related lid deformation changes [10,11] are theoretically possible but not practicable as it is a stationary, complex, slow and inaccurate measurement.…”

Modeling of Thermoacoustic Frequency Characteristics for the Air-Tightness Test Method

“…The main disadvantage of a majority of the methods included in the industrial standards is their destructivity, which limits their use only to the statistical approach. Many authors propose alternative solutions for the methods used in the industry [6][7][8][9][10][11][12][13]. It is possible to divide those methods into two main groups.…”

“…It is possible to divide those methods into two main groups. The first group of methods uses different types of spectroscopy techniques: Fourier transform infrared spectroscopy [6][7][8], Raman spectroscopy [8], and near-infrared spectroscopy [9]. The second group of methods described in [10][11][12][13] uses different piezoelectric, resistive, or capacitive internal structures of the component which monitor the changes of the internal pressure or the humidity increase inside of the package.…”