Postdoc for in-depth assessment of acoustic-optical techniques for in-line metrology and FA

Leuven - PostDoc
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About a week ago

Listen to the defect. Use ‘sound’ to make small defects buried inside a stack of chips, films or interconnects visible.

Postdoc for in-depth assessment of acoustic-optical techniques for in-line metrology and FA

What you will do

In 3-D technology, Si wafers are stacked, thinned and electrically connected using micro-bumps, Cu pads and/or through Si-vias (TSV). To optimize and control these processes, non-destructive measurement techniques are required that can be used to find defects such as voids in TSVs, non-bonded areas or delamination in local regions, high local stresses etc.

Because such wafers contain a lot of metal, not all regions can be inspected by optical microscopy. However, acoustic techniques can be used to both ‘activate’ and ‘sense’ the presence of such defects, even inside and through metals.

The aim of this post-doc position is to investigate the sensitivity and applicability of two acoustic techniques: GHz-Scanning Acoustic Microscopy (GHz-SAM) and Laser Ultrasonics.

In the first, a transducer is used to direct GHz-frequency sound in a sample and the same lens is used to detect the sound reflection from different interfaces in the sample. This technique was shown to be very sensitive to the presence of air (voids, delamination) but the exact sensitivity (depth and x-y) is not known.

In the second, a laser is used to excite a TSV or bump and generate an acoustic wave inside the structure. The resulting surface displacement is monitored using an optical interferometer. It was demonstrated that this allows to detect sub-mm voids in TSVs and estimate the depth of voids.
The aim of this post-doc research is to study the interaction of these acoustic waves with defects, and how they affect the output signals. For this purpose, experiments on dedicated test samples combined with finite element modeling are required. From this, the best measurement methodology and settings should be deduced.
Once models and measurement methodology are established, the aim is to apply these to other microelectronics samples, such as thin-film stacks, and see if other applications of the techniques are possible, such as detection of stress fields, material inhomogeneities, cracks, etc.

What we do for you

We offer you the opportunity to join one of the world’s premier research centers in nanotechnology at its headquarters in Leuven, Belgium. With your talent, passion and expertise, you’ll become part of a team that makes the impossible possible. Together, we shape the technology that will determine the society of tomorrow. 
We are proud of our open, multicultural, and informal working environment with ample possibilities to take initiative and show responsibility. We commit to supporting and guiding you in this process; not only with words but also with tangible actions. Through imec.academy, 'our corporate university', we actively invest in your development to further your technical and personal growth. 
We are aware that your valuable contribution makes imec a top player in its field. Your energy and commitment are therefore appreciated by means of a competitive salary.

Who you are

Apply
  • You have a PhD in physics, engineering (mechanical, material, electrical) or equivalent.
  • We value your experience with acoustic measurement techniques and know-how of the theory of acoustic signals and their propagation in samples and interaction with defects in samples. Experience in modelling of acoustic signals and finite element modelling is a plus. Experience in acoustic-optical measurement methods is also a plus.
  • We are looking for an enthusiastic researcher, who is not afraid to take initiative and enjoys innovative research. You have interest in both the experimental and theoretical side of this topic. 
  • We appreciate your critical mind for data analysis.
  • You can work independently but also enjoy contributing to the team.
  • You are fluent in English and have good communication skills (both written and oral). 
This postdoctoral position is funded by imec through KU Leuven. Because of the specific financing statute which targets international mobility for postdocs, only candidates who did not stay or work/study in Belgium for more than 24 months in the past 3 years can be considered for the position (short stays such as holiday, participation in conferences, etc. are not taken into account).
Apply

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