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September 2007

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Subject:
From:
Leo Higgins <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Leo Higgins <[log in to unmask]>
Date:
Thu, 6 Sep 2007 13:47:59 -0700
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Hi Vladimir,

     The apparent crack on the left edge of the pad and across the top looks like a crack one could expect from a thin film deposited from a drying liquid........at least to me.  The apparent cracks branch off, and terminate in a few places which seem to suggest shrinkage stress relief in the deposited film.  The color of the pad area appears much darker than expected after viewing thousands of SE and BSE images of bond pads.  The brightness of the passivation overlapping the buried edge of the Al pad is considerably greater than the Al pad area, and this is not expected.  Since Al and Si are 13 and 14 in atomic number I am more used to seeing similar gray scales for SE and BSE images, as seen in photo 25b ( I do not know if this is SE or BSE).  Finally, the disturbed Al in the probe mark area is quite bright.  So while much of this may be due to charging, this brightness is more like what I would expect Al to look like.



Best regards,
Leo

          
Leo M. Higgins III, Ph.D.
Sr. Vice President, Engg and Technology
ASAT, Inc. 
13809 Research Blvd., Suite 635
Austin, Texas     78750

office phone   512-249-4758
mobile           512-423-2002
[log in to unmask]
www.asat.com



-----Original Message-----
From: Igoshev, Vladimir [mailto:[log in to unmask]]
Sent: Thursday, September 06, 2007 3:36 PM
To: TechNet E-Mail Forum; Leo Higgins
Subject: RE: [TN] Semi guys, need support


Hi Leo,

Very interesting comments. 

I'm curious, why you think that "hair-like" feature in Fig. 20b
represents a crack. It seems (at least to me) to be too curved and
smooth for a typical crack. I thought it might represent something like
mad-cracks (in a corrosion product), but then I would expect to see some
really dark contrast areas (because of the BSE detector used at a
relatively low kV) and they are not there. In fact the image (20b) is
rather uniform in contrast (with the exception of darker areas along the
edge of the pad due to the surface topography).

Best regards,

Vladimir



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Leo Higgins
Sent: Thursday, September 06, 2007 4:17 PM
To: [log in to unmask]
Subject: Re: [TN] Semi guys, need support

Based upon a quick look at the photos and spectrum:

1. Fluorine peak in the spectrum is not desirable but some F is often
seen so formation of fluorides does not appear to be the main concern.

2. Photo 20b shows what appears to be cracking of a layer of material
overlaying the surface of the pad.  Cracking is clearly visible around
the inside edge of the bond pad and this seems to clearly indicate a
considerable amount, and a nearly continuous layer of contamination
across the bond pad. The photo indicates the use of a backscattered
electron detector, and this type of image shows an enhanced sensitivity
to atomic number, so the very dark surface of the bond pad makes me
believe a low atomic number film is on the surface.  I do not know from
which sample and from which location the spectrum was taken, but if
taken from somewhere on this bond pad, the high Carbon peak makes
organic contamination appear to be a big problem.  

2. It would be very helpful to know from what sample and sample site the
EDX data was collected.  The spectrum shows a fairly large Cl peak.
Photo 9 shows what appears to be corrosion sites or etch pits.  So
perhaps this is related to the Cl due to formation and dissolution of
AlCl3.  

3.  Photos 4 and 25b show pads that appear to exhibit scattered, and
widespread contaminated corrosion sites.  

4.  Is it possible the contamination came from the "chip trays"?  Off
gassing of anti-ESD materials and surfactants could be a source of some
contamination.

This is all I can say without further input. 





Best regards,
Leo

          
Leo M. Higgins III, Ph.D.
Sr. Vice President, Engg and Technology
ASAT, Inc. 
13809 Research Blvd., Suite 635
Austin, Texas     78750

office phone   512-249-4758
mobile           512-423-2002
[log in to unmask]
www.asat.com



-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Steve Gregory
Sent: Thursday, September 06, 2007 10:16 AM
To: [log in to unmask]
Subject: Re: [TN] Semi guys, need support


Hi Inge and Everyone!

I've got your pictures up. Go to:

http://stevezeva.homestead.com/files/RYT809205_25b.jpg

http://stevezeva.homestead.com/files/RYT809205_20b.jpg

http://stevezeva.homestead.com/files/RYT809205_4.jpg

http://stevezeva.homestead.com/files/RYT809205_9.jpg

http://stevezeva.homestead.com/files/Spectrum_RYT809205_flat.jpg

Sorry I can't help with any input, but this kind of stuff is w-a-a-a-y
out of my league...

Steve

 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Hernefjord Ingemar
Sent: Thursday, September 06, 2007 9:01 AM
To: [log in to unmask]
Subject: [TN] Semi guys, need support

 25 micron gold ball bonding bad yield, ball lifts, poor adhesion on Al
pads. Triple diff line tranceiver chip. Weird micrographic exteriour,
EDAX gives C,F,O, Cl,Cu,Al,Fe. Cu can be ppm alloy but the others
unwanted on semi chip bond pads I think. 1kV SEI SEM reveals strange
superficial structure. Chip not contaminated by us, fresh opened chip
trays show this face. Question: what semi manufacturing problem can this
be? Will post a few pics to Steve's gallery.

TrikeMan? 

/Inge

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