Name: in depth analyses of leds by a combination of x-ray computed tomography (ct) and light microscopy (lm) correlated with scanning electron microscopy (sem)
Uploaded: 2016-06-16T13:00:00
Description: Watch this Scientific Journal Video about In Depth Analyses of LEDs by a Combination of X-ray Computed Tomography CT and Light Microscopy LM Correlated with Scanning Electron Microscopy SEM at JoVE.co

The authors kindly acknowledge financial support from the &#34;Akademische Gesellschaft Lippstadt&#34; as well as from the &#34;Ministerium f&#252;r Innovation, Wissenschaft und Forschung des Landes Nordrhein-Westfalen&#34;. Photographs in Figures 1, 2 and 5 courtesy to Markus Horstmann, Hamm-Lippstadt University of Applied Sciences.

1. Sample Preparation for X-ray Computed Tomography (CT)
<ol>
	<li>Glue sample (LED cf. materials section) to a 2 mm &#216; hollow carbon fiber bar of appropriate length using hot-melt adhesive.</li>
	<li>Adjust position of specimen by using a hot-air gun if needed. Fix the sample in the CT-sample chamber using the three-jaw chuck.</li>
</ol>
2. CT Measurement Setup
<ol>
	<li>Perform warmup and centering procedures according to the control software of the X-ray tube. 
	NOTE: Use ...

<ol>
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High Density Packag. , 1-4 (2011).</li><li>Chen, Z., Zhang, Q., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Study+on+the+reliability+of+application-specific+led+package+by+thermal+shock+testing,+failure+analysis,+and+fluid-solid+coupling+thermo-mechanical+simulation.">Study on the reliability of application-specific led package by thermal shock testing, failure analysis, and fluid-solid coupling thermo-mechanical simulation.</a> IEEE Trans. Components, Packag. Manuf. Technol. 2 (7), 1135-1142 (2012).</li><li>Luniak, M., Holtge, H., Brodmann, R., Wolter, K. -. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+Characterization+of+Electronic+Packages+with+Confocal+Microscopy.">Optical Characterization of Electronic Packages with Confocal Microscopy.</a> 2006 1st Electron. Syst. Technol. Conf. 2 (16), 1813-1815 (2006).</li><li>Marks, M. R., Hassan, Z., Cheong, K. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+Methods+for+Ultrathin+Wafer+and+Die+Quality:+A+Review.">Characterization Methods for Ultrathin Wafer and Die Quality: A Review.</a> IEEE Trans. Components, Packag. Manuf. Technol. 4 (12), 2042-2057 (2014).</li><li>Rosc, J., Hammer, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reliability+assessment+of+contact+wires+in+LED-devices+using+in+situ+X-ray+computed+tomography+and+thermo-mechanical+simulations.">Reliability assessment of contact wires in LED-devices using in situ X-ray computed tomography and thermo-mechanical simulations.</a> Proc. 5th Electron. Syst. Technol. Conf. , 1-6 (2014).</li><li>Zhaohui, C., Qin, Z., Kai, W., Xiaobing, L., Sheng, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reliability+test+and+failure+analysis+of+high+power+LED+packages.">Reliability test and failure analysis of high power LED packages.</a> J. Semicond. 32 (1), 014007 (2011).</li><li>Hamon, B., Bataillou, B., Hamon, B., Mendizabal, L., Gasse, A., Feuillet, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=N-contacts+degradation+analysis+of+white+flip+chip+LEDs+during+reliability+tests.">N-contacts degradation analysis of white flip chip LEDs during reliability tests.</a> 2014 IEEE Int. Reliab. Phys. Symp. , FA.1.1-FA.1.6 (2014).</li><li>Tsai, M. -. Y., Tang, C. -. Y., Yen, C. -. Y., Chang, L. -. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bump+and+Underfill+Effects+on+Thermal+Behaviors+of+Flip-Chip+LED+Packages:+Measurement+and+Modeling.">Bump and Underfill Effects on Thermal Behaviors of Flip-Chip LED Packages: Measurement and Modeling.</a> IEEE Trans. Device Mater. Reliab. 14 (1), 161-168 (2014).</li><li>Wang, F. -. K., Lu, Y. -. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Useful+lifetime+analysis+for+high-power+white+LEDs.">Useful lifetime analysis for high-power white LEDs.</a> Microelectron. Reliab. 54 (6-7), 1307-1315 (2014).</li><li>Liu, Y., Zhao, J., Yuan, C. C. -. A., Zhang, G. Q., Sun, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chip-on-Flexible+Packaging+for+High-Power+Flip-Chip+Light-Emitting+Diode+by+AuSn+and+SAC+Soldering.">Chip-on-Flexible Packaging for High-Power Flip-Chip Light-Emitting Diode by AuSn and SAC Soldering.</a> IEEE Trans. Components, Packag. Manuf. Technol. 4 (11), 1754-1759 (2014).</li><li>Thomas, C., Edelmann, M., Lysenkov, D., Hafner, C., Bernthaler, T., Schneider, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Correlative+Light+and+Electron+Microscopy+(CLEM)+for+Characterization+of+Lithium+Ion+Battery+Materials.">Correlative Light and Electron Microscopy (CLEM) for Characterization of Lithium Ion Battery Materials.</a> Microsc. 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The advantages of this multimodal approach consist in the location-dependent correlation of the acquired data. The multimodal approach described here should be contrasted in subsequent analyses with each technique separately. For example, luminescence properties visible in LM can be linked to compositions as detected using SEM/EDS. The volume information obtained by CT can be extended with in depth analyses of cross-sections prepared in a targeted fashion. CT data also enable fast location of possible areas of interest i...

This article demonstrates the potential and advantages of a combination of X-ray computed tomography (CT) with correlative light and electron microscopy (CLEM) for the exemplary in depth characterization of light emitting diodes (LED). With this technique it is possible to plan the micro preparation of the LED in such a fashion that while a cross section can be imaged microscopically the electrical functionality is preserved in the remainder of the specimen. The procedure has several unique features: firstly, the planned micro preparation by aid of the rendered volume of the entire sample obtained by CT; secondly, the observation of the LED by light microscopy (LM) with the complete variety of imaging techniques available (bright and dark field, polarization contrast, etc.); thirdly, observation of the LED in operation by LM; fourthly, observation of identical regions with the full variety of electron microscopy imaging techniques comprising secondary electron (SE) and back scatter electron (BSE) imaging, as well as energy dispersive X-ray fluorescence spectroscopy (EDX).
LEDs for illumination applications are designed to emit white light, although in certain applications color variability may be favorable. This broad emission cannot be achieved by emission from one compound semiconductor, since LEDs emit radiation in a narrow spectral band (circa 30 nm full width half maximum (FWHM)). Therefore white LED light is commonly generated by the combination a blue LED with phosphors which convert the short-wavelength radiation into broad emission over a large spectral range1. Color variable LED solutions usually make use of at least three primaries, which generally results in higher market prices.2
The use of either CT, LM or SEM is of course well established (e.g., in failure analysis for LEDs3-15), however the comprehensive and purposeful combination of all three techniques described here may offer new insights and will enable faster tracks towards meaningful characterization results.
From 3D microstructural analysis of the packaged device in CT the regions of interest (ROIs) can be identified and selected. With this non-destructive method, electrical connections can also be identified and considered for further preparation. The precise preparation of a 2D cross section allows investigations of the device in operation despite the destructive nature of this method. The cross section can now be characterized by CLEM16,17 which enables a very efficient and flexible characterization of identical ROIs with LM as well as SEM. By this approach, the advantages of both microscopy techniques can be combined. For example, a fast identification of ROIs in the LM is followed by high-resolution imaging in the SEM. But furthermore, the correlation of information from the LM (e.g., color, optical properties, particle distribution) with the visualization and analysis techniques of the SEM (e.g., particle size, surface morphology, element distribution) allows a deeper understanding of functional behavior and microstructure within a white LED.

<table border="0" cellpadding="0" cellspacing="0" width="758">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:263px;">X-Ray Computer Tomograph</td>
			<td style="width:119px;">General Electric</td>
			<td style="width:139px;">not applicable</td>
			<td style="width:239px;">type: nanotom s research edition</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:263px;">acquisition software</td>
			<td style="width:119px;">General Electric</td>
			<td style="width:139px;">not applicable</td>
			<td>phoenix Datos| x2 acquisition and corresponding manual</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:263px;">reconstruction software</td>
			<td style="width:119px;">General Electric</td>
			<td style="width:139px;">not applicable</td>
			<td>phoenix Datos| x2 acquisition and corresponding manual</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:263px;">rendering software</td>
			<td style="width:119px;">Volume Graphics</td>
			<td style="width:139px;">not applicable</td>
			<td>VGStudio Max 2.2 and corresponding manual</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:263px;">grinder (manual)</td>
			<td style="width:119px;">Struers</td>
			<td align="right" style="width:139px;">5296327</td>
			<td>Labopol 21</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:263px;">sample holder</td>
			<td style="width:119px;">Struers</td>
			<td align="right" style="width:139px;">4886102</td>
			<td>UniForce</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:263px;">grinder (automated)</td>
			<td style="width:119px;">Struers</td>
			<td align="right" style="width:139px;">6026127</td>
			<td>Tegramin 25</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:263px;">epoxy resin/hardener</td>
			<td style="width:119px;">Struers</td>
			<td style="width:139px;">40200030/40200031</td>
			<td>Epoxy fix resin / Epoxy fix hardener</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:263px;">Ethanol</td>
			<td style="width:119px;">Struers</td>
			<td align="right" style="width:139px;">950301</td>
			<td>Kleenol</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:263px;">Light Microscope</td>
			<td style="width:119px;">Zeiss</td>
			<td style="width:139px;">not applicable</td>
			<td>Axio Imager M2m&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:263px;">Electron Microscope</td>
			<td style="width:119px;">Zeiss</td>
			<td style="width:139px;">not applicable</td>
			<td>Sigma&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:263px;">CLEM software</td>
			<td style="width:119px;">Zeiss</td>
			<td style="width:139px;">not applicable</td>
			<td>Axio Vision SE64 Rel.4.9 and corresponding manual</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:263px;">CLEM sample holder</td>
			<td style="width:119px;">Zeiss</td>
			<td style="width:139px;">432335-9101-000</td>
			<td>Specimen holder CorrMic MAT Universal B</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:263px;">SEM Adapter for CLEM sample holder</td>
			<td style="width:119px;">Zeiss</td>
			<td style="width:139px;">432335-9151-000</td>
			<td>SEM Adapter for Specimen holder CorrMic MAT Universal B</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:263px;">sputter coater</td>
			<td style="width:119px;">Quorum</td>
			<td style="width:139px;">not applicable</td>
			<td>Q150TES</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:263px;">EDS detector</td>
			<td style="width:119px;">R&#246;ntec</td>
			<td style="width:139px;">not applicable</td>
			<td>X-Flash 1106</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:263px;">solder</td>
			<td style="width:119px;">Stannol</td>
			<td align="right" style="width:139px;">535251</td>
			<td>type: HS10</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:263px;">LED</td>
			<td style="width:119px;">Lumileds</td>
			<td style="width:139px;">not applicable</td>
			<td>LUXEON Rebel warm white, research sample</td>
		</tr>
	</tbody>
</table>

in depth analyses of leds by a combination of x-ray computed tomography (ct) and light microscopy (lm) correlated with scanning electron microscopy (sem)

In failure analysis, device characterization and reverse engineering of light emitting diodes (LEDs), and similar electronic components of micro-characterization, plays an important role. Commonly, different techniques like X-ray computed tomography (CT), light microscopy (LM) and scanning electron microscopy (SEM) are used separately. Similarly, the results have to be treated for each technique independently. Here a comprehensive study is shown which demonstrates the potentials leveraged by linking CT, LM and SEM. In depth characterization is performed on a white emitting LED, which can be operated throughout all characterization steps. Major advantages are: planned preparation of defined cross sections, correlation of optical properties to structural and compositional information, as well as reliable identification of different functional regions. This results from the breadth of information available from identical regions of interest (ROIs): polarization contrast, bright and dark-field LM images, as well as optical images of the LED cross section in operation. This is supplemented by SEM imaging techniques and micro-analysis using energy dispersive X-ray spectroscopy.

The characterized LED is shown in Figure 1. It is a white emitting LED with a Chip size of 1 x 1 mm2 and a partially ceramic luminescent color converter. Gluing the LED in a slightly slanted position onto a carbon fiber bar avoids CT artifacts caused by sample symmetry (Figure 2). Results of the CT measurement allow for planning the position of the cross section of the sample, and ensure electrical operability after partial abrasion (Fi...

Watch this Scientific Journal Video about In Depth Analyses of LEDs by a Combination of X-ray Computed Tomography CT and Light Microscopy LM Correlated with Scanning Electron Microscopy SEM at JoVE.co

In Depth Analyses of LEDs by a Combination of X-ray Computed Tomography CT and Light Microscopy LM Correlated with Scanning Electron Microscopy SEM

A workflow for comprehensive micro-characterization of active optical devices is outlined. It contains structural as well as functional investigations by means of CT, LM and SEM. The method is demonstrated for a white LED which can be still be operated during characterization.

In Depth Analyses of LEDs by a Combination of X-ray Computed Tomography (CT) and Light Microscopy (LM) Correlated with Scanning Electron Microscopy (SEM)

In failure analysis, device characterization and reverse engineering of light emitting diodes (LEDs), and similar electronic components of ...

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