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(TSVs) drilled for a 3D-IC process. The (Figure 5a), DF (Figure 5b), and CF
TSVs are about 30µm wide and 20µm illumination (Figure 5c). All four vias
deep and the pitch between TSVs is about have organic residue in them but it is
120µm. The panel is covered with a metal difficult to see in the BF and DF images.
layer and has been through a “de-smear” The residue is clearly visible in the CF
cleaning process to remove organic images and the brightness of the residue
residue from the vias. Inspections with indicates the amount of residue present
BF and DF illumination have difficulty (brighter is more). Background noise from
detecting the organic residue because the metal surface variations can be seen in
of its transparency. Figure 5 shows the BF and DF images, but is not visible
10X images of the same TSVs under BF in the CF image.

LEADERS IN
MICRO DISPENSING

TECHNOLOGY

SMALL REPEATABLE VOLUMES
ARE A CHALLENGE, BUT NOT
IMPOSSIBLE IF YOU HAVE BEEN Figure 6: CF inspection results shown as a a)
CREATING THEM AS LONG AS WE HAVE. (top) defect map, and b) (bottom) as a histogram
distinguishing lighter and heavier deposits.

Figure 6 shows the CF inspection
TO DO IT WELL, result of the TSV panel. The dots on the
panel map represent defect locations
WE PROVIDE THREE THINGS: and show organic residues present in
TSVs across the entire panel, indicating
that the “de-smear” cleaning process
did not work as expected. The TSVs
Dispensing Expertise in a variety of microelectronic will be filled with metal and organic
packaging applications. residue may cause deplanarization
and lead to con nect ivit y issues.
Feasibility Testing & Process Verification based Organic residue can also add electrical
on years of product engineering, material flow testing resistance in TSVs.
and software control. FOPLP sample. The next example
is a 450mm molding compound panel.
Product Development for patented valves, Figure 7 shows 4X BF (Figure 7a) and
dispensing cartridges, needles, and accessories. CF (Figure 7b) images of RDL and
under bump metallization (UBM) pad
on the panel. The background metal
surface underneath the transparent
f ilm looks just like the RDL and
t h e U BM p a d i n t h e BF i m a ge ,
making it difficult to distinguish the
Our Micro Dispensing product line is proven and trusted by
manufacturers in semiconductor, electronics assembly, medical upper layer metal patterns from the
device and electro-mechanical assembly the world over. underlying metal layer. The metal
texture and graininess also add noise
www.dltechnology.com.
to the image, making it difficult to
detect defects and interfering with
216 River Street, Haverhill, MA 01832 • P: 978.374.6451 • F: 978.372.4889 • info@dltechnology.com the detection algorithm. Inspection
with BF illumination resulted in high

42 Chip Scale Review January • February • 2021 [ChipScaleReview.com]
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