(r7) Connectivity < ATLAS/PUUKA

ATLAS/PUUKA Web>Tasks>Connectivity (revision 7) (raw view)~~EditAttach~~

The connective task has two main areas of work, TSV and flip-chip bonding development.

---++ Flip-chip bonding at STFC-RAL

STFC/RAL are developing a fine pitched Indium flip-chip process. The samples first have an under bump metal (UBM) layer deposited upon them where the bump is to be grown. The UBM used to date is Ti/W, Ni, Au. The Ti/W is an adhesion layer to the Aluminium pad of the device. The nickel is the solderable metal layer and the Au is an oxidation barrier. The indium is deposited in a thermal reactor at RAL. The Indium is heated under vacuum and condenses on the sample that is held at a lower temperature. The samples can then be flip-chipped bonded. The flip-chip process is to work at room temperature or slightly elevated temperatures.

There is some worry that the Indium bumps require more pressure to form a bump than should be the case. One suggestion for this high pressure is that the gold used in the UBM is moving into the Indium and forming an Indium/Gold alloy which requires more force to deform. A SEM/FIB/EDX study of an Indium bump formed on a silicon substrate was performed in Glasgow to try and test the hypothesis that the gold had moved into the Indium. The report is found here:

   * [[%ATTACHURL%/Report_on_SEM_Secondary_electron_images_and_EDX_measurements_on_In_bumps_from_RAL.docx][Report_on_SEM_Secondary_electron_images_and_EDX_measurements_on_In_bumps_from_RAL.docx]]: Report on SEM for Indium bump from RAL

The report's conclusion is that the gold does indeed appear to have migrated into the Indium bump.

---++ First Indium Flip-chip bonded FE-I4

The first indium assembly wafer ID : VMB6NJH die 3

Sensor : CPII Live FE-I4 MPI Guard IBL

<br /> [[%ATTACHURLPATH%/Indium_BumpYield_28032014.pptx][Indium_BumpYield_28032014.pptx]]: Bump Yield Studies March 2013

---++ Indium Flip-Chipped Modules September 2014
---+ 

Indium bumps require pressure only to make connections so no high temperatures are required to melt alloy, which reduces bowing effects.

---++++ Modules under test:

| *ID* | *Bond Force* | *Comment* |
| 14-07-24-S2 | 20kg | biased to 40V |
| 14-07-25-S2 | 10kg | short on VDDA line |
| 14-07-25-S4 | 5kg | biased to 40V (operated at 20V) |

---++ IV Scans

IV Scans on wafer and after processing

<img alt="Screen_Shot_2014-09-25_at_14.50.52.png" height="422" src="%ATTACHURL%/Screen_Shot_2014-09-25_at_14.50.52.png" width="613" />

---+ Characterisation
---+++ USBPix

Bump yield studies performed in August 2014 by Dan Smaranda and Richard Bates

[[%ATTACHURL%/21082014_Indium-DanSmaranda.pdf][21082014_Indium-DanSmaranda.pdf]]
---+++ RCE System

All modules tuned to and operated at 3000e threshold, 10ToT @ 16ke reference charge.
---+++++ Tuning

Module 14-07-24_S2:

Tune to 3000e, 10ToT @ 16ke

[[%ATTACHURL%/14-07-24_S2_3000eTuning.pptx][14-07-24_S2_3000eTuning.pptx]]

Module 14-07-25_S4:

Tune to 3000e, 10ToT @ 16ke

[[%ATTACHURL%/14-07-25_S4_3000eTuning.pptx][14-07-25_S4_3000eTuning.pptx]]
---+++++ Bump Yield Studies 

Bump Yield assessed by performing Threshold Scans with and without sensor bias and performing source scans with Strontium-90 beta source and Americium-241 60keV gamma ray source.

[[%ATTACHURL%/Indium-Characterisation_0914.pptx][Indium-Characterisation_0914.pptx]]

---++ Bump yield results
| *Module* | *Bond Force* | *<p>Bump Yield</p> <p>(Sigma plot)</p>* | *<p>Bump Yield</p> <p>(Source Scans)</p>* |
| Indium1 | ? | 99.48% | 99.38% |
| 14-07-24-S2 | 20kg | 82.85% | 82.35% |
| 14-07-25-S4 | 5kg | 23.37% | 22.54% |
---++ Comments

<br /><br />
---++ [[TSV]]

Details of the TSV activity are given on the next page.

-- Main.RichardBates - 2011-06-09

Attachments

Topic attachments
I	Attachment	History	Action	Size	Date	Who	Comment
pptx	14-07-24_S2_3000eTuning.pptx	r1	manage	159.3 K	2014-10-01 - 14:43	KateDoonan
pptx	14-07-25_S4_3000eTuning.pptx	r1	manage	154.1 K	2014-10-01 - 14:43	KateDoonan
pdf	21082014_Indium-DanSmaranda.pdf	r1	manage	598.7 K	2014-09-25 - 13:38	KateDoonan	Bump Yield Studies by Richard Bates and Dan Smaranda 08/2014
pptx	Indium-Characterisation_0914.pptx	r1	manage	580.0 K	2014-09-25 - 13:39	KateDoonan	Bump yield studies by Kate Sexton
pptx	Indium_BumpYield_28032014.pptx	r1	manage	636.5 K	2014-04-03 - 07:27	RichardBates	Bump Yield Studies March 2013
docx	Report_on_SEM_Secondary_electron_images_and_EDX_measurements_on_In_bumps_from_RAL.docx	r2 r1	manage	9890.4 K	2012-06-14 - 14:27	RichardBates	Report on SEM for Indium bump from RAL
png	Screen_Shot_2014-09-25_at_14.50.52.png	r1	manage	156.1 K	2014-09-25 - 13:51	KateDoonan	IV Characteristics of Modules before and after processing

Topic revision: r7 - 2014-10-01 - KateDoonan

ATLAS/PUUKA