Improved Inspection of Miniaturized Interconnections by Digital X-ray Inspection and Computed Tomography

Transcription

1 Eufanet 3D Workshop, Nov 28/29, 2011 Toulouse/France Improved Inspection of Miniaturized Interconnections by Digital X-ray Inspection and Computed Tomography Jens Lübbehüsen / Thomas Hemberger GE Sensing & Inspection Technologies, Wunstorf/D Limonest/F

2 Improved Inspection... Contents 1. The purpose of non-destructive testing by X-ray in electronics 2. Principles of X-ray inspection and of Computed Tomography, Resolution 3. Application examples: TSV, QFN-A microvias 4. Summary 2

3 The purpose of NDT by X-ray in electronics 1. Production control without damaging products 2. Failure analysis before to or instead of using destructive methods (which might destroy the defect signature) 3. Monitoring the changes in devices during reliability test 3

4 Principles of X-ray Inspection What are X-rays? X-rays are electromagnetic waves like light. Their wavelength is in the range of 0,001 pm to 1 nm Propagate rectilinear, no refraction effects etc. considered 4

5 Principles of X-ray Inspection contrast resolution + dynamics X-ray image 5 bank notes at 50 kv GE DXR flat panel Commercially available 16bit flat panel 5

6 Principles of X-ray Inspection Resolution and penumbra effect Magnification geom: 2.000x total: x Microfocus: F = 2-3 µm nanofocus : F = 600 nm (0,6 µm) resolution limit = focal spot size F detail detectability = appr. 1/3 F (depends on object) Geometric unsharpness: U = (M-1) F 6

7 Principles of X-ray Inspection Tube types as used in electronics applications transmission: nanofocus: smaller minimum FOD higher M lenses, apertures and stabilised acceleration voltage minimise focal spot size. 7

8 Application examples Gold bond wires (LED) 2D image nanofocus contrast enhancement The small gap between land and ball bond indicates that the ball bond is slightly lifted. 8

9 Volume-CT Principle of operation CT is based on a set of X-ray images taken whilst rotating the sample by

10 Resolution System Three contributions from apparatus: voxel size V focal spot size F mechanics U=(M-1)F V=P/M The focal spot size is the ultimate limit of resolution. 10

11 Resolution Sample size d voxel size density tube power focal spot size For a full size scan the voxel size V = d/p where P is number of detector pixels. ROI scans are possible in many cases, Purpose: improve resolution: V = ROI/P 11

12 Application TSV 2D image nanofocus Voiding in TSV Sample provided by contrast enhancement 55 ovhm (detector tilt) view of TSV. A via is not totally filled with copper. 12

13 Application TSV 2D image nanofocus Voiding in TSV Sample provided by contrast enhancement The via with voiding at higher magnification under 45 ovhm (detector tilt) view angle. 13

14 Application TSV nano ct Sample provided by visualisation in pseudo colours 3D visualisation of TSV. 14

15 Application TSV nano ct Sample provided by visualisation in pseudo colours Software simulate the cross section to voiding. 15

16 Application examples QFN-A embedded chip module photography Manufactured by Fraunhofer IZM, Berlin 16

17 Application examples QFN-A embedded chip module Resin: 90 µm schematic 30 µm re Chip: 50 µm Die attach Film (DAF): 20 µm FR4: 50 µm Cu: 12 µm Manufactured by Fraunhofer IZM, Berlin 17

18 Application examples QFN-A embedded chip module nanofocus X-ray image Manufactured by Fraunhofer IZM, Berlin 18

19 Application examples QFN-A embedded chip module nanofocus X-ray image GE DXR250RT 1µm/pixel 8 x 5 s = 40 s Operable sample: Shift detected Vias are of homogenous greyvalue 19

20 Application examples QFN-A embedded chip module nanofocus X-ray image GE DXR250RT 1µm/pixel 8 x 5 s = 40 s Defective sample: Shift detected Bright spot in the centres 20

21 Application examples QFN-A embedded chip module nanofocus X-ray image GE DXR250RT 1µm/pixel 8 x 5 s = 40 s Defective sample: Central voids and shift are visible. The vias are lifted from the pads. 21 J. Lübbehüsen T. Hemberger / Improved...

22 Application examples QFN-A embedded chip module nanofocus X-ray image GE DXR250RT 0,4 µm/pixel 64 x 0,333 s = 21 s Central voids and shift detected 22

23 Application examples QFN-A embedded chip module nanofocus X-ray image 4 Mpx image chain 0,4 µm/pixel 128 x 0,333 s = 42 s Central voids and shift detected 23

24 Application QFN-A Embedded chip module QFN-A2 package 3D CT results sample No.201 (fail) 130 kv 230 µa 12,2 µm/voxel 16 min scan time detector: GE DXR 250 RT E Overview of the entire sample acquisition sequence 24

25 Application QFN-A Embedded chip module QFN-A2 package 3D CT results sample No.201 (fail) 100 kv 110 µa 2,2 µm/voxel 65 min scan time detector: GE DXR 250 RT E Detail of reconstructed volume Blue: Chip, Red Chip pad, Yellow: copper track, Orange: microvia, Green: FR4 fibres 25

26 Application examples QFN-A embedded chip module nanofocus CT slice 4 Mpx image chain 1,2 µm/voxel 4h Defective sample: Lifted and not compressed The vias are hollow 26

27 Application examples QFN-A embedded chip module nanofocus CT slice GE DXR250RT 1,2 µm/voxel 4h Comparison good - bad 27

28 Application examples QFN-A embedded chip module nanofocus CT slice GE DXR250RT 1,2 µm/voxel 4h Comparison CT slice mechanical section (method comparison with different samples) 28

29 Application examples QFN-A embedded chip module nanofocus CT 3D visualisation GE DXR250RT 1,2 µm/voxel 4h Defective sample: Vias Lifted and not compressed 29

30 Summary nanoct, i.e. CT based on nanofocus images, yields (sub-) micron detail detectability in three dimensions, depending on the size of the sample. nanofocus X-ray inspection and nanoct partially can substitute or complement destructive methods. Due to better signal to noise ratio the effective image resolution could be improved again. In electronics, 3D integrated devices are a major application. => acknowledgements: ASTRI, Fraunhofer IZM 30

31 Eskerrik asko! Muchas gracias! Grazie mille! Merci beaucoup! Muito obrigado! 谢谢! धयव द! धयव द תודהרבה! Mange tak! راز! Vielen Dank! Большое cпасибо! Tack så mycket! どうもありがとうございます!

32 Contact GE Sensing & Inspection Technologies GmbH Niels-Bohr-Strasse 7 D Wunstorf, Germany info@phoenix-xray.com GE Sensing & Inspection Technologies SCS - Limonest Branch Office 68 chemin des Ormeaux F Limonest, France phoenix-limonest@ge.com