1. Inspiration to solve a difficult yield
issue-interlayer delamination in
polyimide dielectrics
Paul A. Zucco
While at IBM Microelectronics, East Fishkill , NY Facility

2. Articles
Interdiffusion in Polyimide Thin Films
1986 MRS Spring Meeting.
Article author query
kramer ej [Google Scholar]
volksen w [Google Scholar]
russell tp [Google Scholar]
E. J. Kramera1, W. Volksena2 and T. P. Russella2
a1 Department of Materials Science and the Materials Science Center, Cornell University, Ithaca, NY
14850
a2 IBM Almaden Research Center, San Jose, CA 95120
Abstract
The interdiffusion in thin films of polyimide has been investigated using the forward recoil spectrometry
(FRES) technique. Films 5–10 μm in thickness of polyamic acid spin coated onto a silicon substrate were
imidized at a temperature TI. A second film, ∼300Å in thickness of perdeuterated polyamic acid was
spin-coated onto the first layer and heated to a temperature TD to allow interdiffusion of the two films
and imidization of the second coating. Depth profiling of the deuterated polymer by FRES showed that
no interdiffusion occurred if TI>TD and TI>200°C. Substantial interdiffusion occurred if TD>TI and TI<400°
C. Time averaged tracer diffusion coefficients were found to vary with the TD and TI, as well as the
length of time allowed for interdiffusion. Since conversion of the deuterated polyamic acid to polyimide
occurs at the diffusion temperature, the results are consistent with a relatively large diffusion
coefficient for the polyamic acid (D>2.5× 10−14 cm2/sec) which decreases to a negligible value as the
molecule is fully converted to the corresponding polyimide
Inspiration from the Literature:

3. Challenge
1. Create a dual layer metalized Polyimide dielectric coating
2. Double layer polyimide must survive a chemical polishing step

4. Issue-yield loss
Root Cause:
Second layer of polyimide applied as polyamic acid was delaminating due to shear
stress from the chemical mechanical polish

5. Proposed Solution
1. Reduce shear stress on film
2. Improve inter-polymer diffusion
3. Under cure first layer to allow diffusion without crazing

6. Steps
1. Could not reduce stress in shear. Cu metal was being removed along with polyimide
to create a plannarized surface
The main goal became improving the strength of the interface between the two coatings.
This is where the work performed by Prof. Kramer and the Almaden Research team
directed us to:
a. Putdown the first polyamic acid film and only partially imidize the film. This allowed the
solvent from the second layer to pre-swell the surface.
b. This allowed the polymer chains to inter-diffuse prior to full imidization of both films.

7. Results
By establishing the extent of imidization of the first layer using FTIR and by fully curing the
Two layers the yield loss became less than 1%.

8. Conference Paper Flip-chip interconnection technology for advanced thermal conduction modules
S.K. Ray S.K. Ray Remove suggestion K. Beckham K.
Beckham Remove suggestion R. Master R. Master Remove
suggestion IBM Corp., East Fishkill, NY DOI: 10.1109/ECTC.1991.163967 Conference:
Electronic Components and Technology Conference, 1991. Proceedings., 41st Source: IEEE Xplore
ABSTRACT Area array solder bumps on silicon devices, known as C4 balls,have been successfully used in
terminating logic and memory devices toceramic substrates in numerous IBM products over two decades.
With theIBM System 390/ES9000 series of mainframe computers, this highlyreliable chip termination
technology has achieved improvedinterconnection density and total number of chip I/O connections
permodule. In addition, in the models 820 and 900 of ES9000 series, a novelmaterials set, namely glass-
ceramic with Cu internal metallization alongwith thin-film redistribution wiring on top, has been
introduced formultilayered ceramic substrates. Key elements of advanced glass-ceramicsubstrate
technology relevant to flip-chip joining are reviewed. This isfollowed by a discussion of device join and
replace processes used inadvanced thermal conduction modules which also have decouplingcapacitors
which are attached by C4 solder reflow. Optimization of thetop surface metallurgy and device join
parameters necessary to achievereliable joining of more than 70000 solder balls per module is discussed
Flip-chip interconnection technology for advanced thermal conduction modules - ResearchGate. Available
from: http://www.researchgate.net/publication/3523482_Flip-
chip_interconnection_technology_for_advanced_thermal_conduction_modules [accessed Oct 14, 2015].