In-Operando X-ray diffraction imaging of thermal strains in fully packaged silicon devices

Abstract

The application of X-ray Diffraction Imaging to measure in operando thermal strains at individually powered components within fully packaged LM3046 silicon devices is described. It is shown that as the local strains increase with power dissipated, above a threshold power loading, the associated region of enhanced X-ray intensity increases monotonically. The changes in contrast in the image are discussed. Asterism in section topographs changes sign as the slit is moved across the component, consistent with lattice strain around the device due to the thermal expansion. Above a threshold power, this asterism increases linearly with power loading. By simultaneous measurement of the package surface temperature it is possible to deduce the local component temperature from the extent of the contrast in the X-ray image.

X-ray diffraction imaging of fully packaged n–p–n transistors under accelerated ageing conditions

“…As reported in our previous paper (Tanner et al, 2019), the length of the direct image L D varied quadratically with power dissipated for all the devices measured. Though there was a substantial linear component to the curves, in all cases inclusion of the quadratic term was required to accommodate the measurement error bars.…”

“…Crowding of the emitter-collector current results in heating towards the edge of the collector area, extending the hot spot as the power dissipated increases. [Although the increase in temperature counters the current crowding to some extent, as the temperature T is in kelvin, the change is estimated to be only a factor of two (Tanner et al, 2019)…”

“…Using high-energy XRDI in white beam mode, we demonstrated that the development of the localized thermal strain around the individual devices inside the fully encapsulated LM3046 chip packages can be monitored (Tanner et al, 2019). The device temperature associated with these strains can be estimated by simultaneously measuring the external package temperature.…”

X‐Ray Topography—More than Nice Pictures

“…This fast and nondestructive method allows the tilt or strain measurement in operando as recently reported by Tanner et al [74] and could be also transferred from synchrotron to laboratorybased X-ray section mapping. [71]…”

“…As a last example the fast and nondestructive metrology for packaged electronic devices will be given. The so called B-spline X-Ray diffraction imaging (B-XRDI) is proposed also for in operando studies by the group of McNally [69,70,71,72] and transferred to laboratory sources by Tanner et al [73,74] The strength of X-ray topography in material research will be demonstrated in the following by example of mainly electronic materials, which can be easily transferred to other crystalline materials too.…”