Passivation Cracks in a Four-Level Metal Low-K Dielectric Backend Process

Author(s):  
Michael C. Olewine ◽  
John F. DiGregorio ◽  
Gus J. Colovos ◽  
Kevin F. Saiz ◽  
Hongjiang Sun

Abstract Mechanical stress problems in integrated circuit devices are becoming more severe as the number of metal interconnect levels increases and new materials such as low-k dielectrics are introduced. We studied dielectric cracking in a four-level Al-Cu interconnect structure that uses hydrogen silsesquioxane (HSQ), a low dielectric constant (low-k) material. The cracks extended down through the passivation layers to the HSQ layer. For the first time we report on passivation dielectric cracks directly related to the level of residual fluorine in a plasma enhanced chemical vapor deposition (PECVD) reactor. It is shown that a silicon nitride pre-coat deposition removes fluorine (F) from the reactor ambient and prevents the dielectric cracks.

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Zhao Xiong-Yan ◽  
Wang Ming-Zhu ◽  
Wang Zhi

AbstractA novel low dielectric constant polymer, plasma-polymerized 1-cyano isoquinoline (PPCIQ) was prepared by plasma polymerization for the first time. The structure and surface compositions of the deposited PPCIQ thin films were investigated by Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). The results show that a high retention of the aromatic ring structure of the starting monomer in the deposited plasma films is obtained when a low discharge power of 15 W was used during film formation. In the case of higher discharge power of 35 W, more severe monomer molecular fragmentation can be observed. The dielectric properties measurements show that a low dielctric constant of 2.62 can be obtained for PPCIQ thin film deposited at 15 W.


1999 ◽  
Vol 565 ◽  
Author(s):  
J. N. Bremmer ◽  
D. Gray ◽  
Y. Liu ◽  
K. Gruszynski ◽  
S. Marcus

AbstractLow dielectric constant hydrogen silsesquioxane films were achieved by rapid thermal cure processing with production viable equipment. A reduced dielectric constant of k = 2.5–2.6 is demonstrated by optimizing rapid thermal cure process conditions to produce low density hydrogen silsesquioxane thin films. This is a significant reduction relative to production proven furnace cure processed hydrogen silsesquioxane with k = 2.9. Concurrent with reduced k performance is a characteristic film expansion which contributes to formation of a low density structure. A mechanism for film expansion and relevance to low k performance is described; and issues relative to integration of rapid thermal processed low k hydrogen silsesquioxane are discussed.


1998 ◽  
Vol 511 ◽  
Author(s):  
E. O. Shaffer ◽  
M. E. Mills ◽  
D. Hawn ◽  
M. Van Gestel ◽  
A. Knorr ◽  
...  

ABSTRACTCurrently, the IC industry is researching the integration of a variety of materials to meet the low dielectric constant requirement for improved back-end of line (BEOL) interconnect performance. One critical dimension for successful ntegration of these new materials is maintaining mechanical integrity through multilayer processes. This includes both cohesive and adhesive fracture resistance. The latter adds additional complexity in that adhesive toughness is a function of the adherend materials and the processes used to join them. Hence, many good dielectric materials may be rematurely eliminated from further research not because of inherently poor adhesion but because of the necessity to optimize processing strategies.In this paper, we use the modified Edge Liftoff Test (m-ELT) to quantify the mechanical adhesion of multilayer blanket coatings. A specific example is used to demonstrate the utility of combining the m-ELT with surface analysis to optimize the reliability of low-K dielectric resins for use in ULSI applications. The system studied consists of a Cyclotene™ 5021(BCB) low-K material integrated with CVD aluminum for single level, damascene structures. The effects of liner layer metallurgy and surface plasma treatments are measured. Surface analysis is done on the failed parts to understand the location of the failure. In this way recommendations for process optimization can be made.


1999 ◽  
Vol 565 ◽  
Author(s):  
Hideki Gomi ◽  
Koji Kishimoto ◽  
Tatsuya Usami ◽  
Ken-ichi Koyanagi ◽  
Takashi Yokoyama ◽  
...  

AbstractThe technologies utilizing Fluorinated Silicon Oxide (FSG, k=3.6) and Hydrogen Silsesquioxane (HSQ, k=3.0) have been established for 0.25-μm and 0.18-μm generation ULSIs. However, low-k materials for the next generation ULSIs, which have a dielectric constant of less than 3.0, have not become mature yet. In this paper, we review process integration issues in applying FSG and HSQ, and describe integration results and device performance using Fluorinated Amorphous Carbon (a-C:F, k=2.5) as one of the promising low-k materials for the next generation ULSIs.


1999 ◽  
Vol 564 ◽  
Author(s):  
Hideki Gomi ◽  
Koji Kishimoto ◽  
Tatsuya Usami ◽  
Ken-ichi Koyanagi ◽  
Takashi Yokoyama ◽  
...  

AbstractThe technologies utilizing Fluorinated Silicon Oxide (FSG, k=3.6) and Hydrogen Silsesquioxane (HSQ, k=3.0) have been established for 0.25-µm and 0.1 8-µm generation ULSIs. However, low-k materials for the next generation ULSIs, which have a dielectric constant of less than 3.0, have not become mature yet. In this paper, we review process integration issues in applying FSG and HSQ, and describe integration results and device performance using Fluorinated Amorphous Carbon (a-C:F, k=2.5) as one of the promising low-k materials for the next generation ULSIs.


MRS Bulletin ◽  
1997 ◽  
Vol 22 (10) ◽  
pp. 33-38 ◽  
Author(s):  
Nigel P. Hacker

Low-dielectric-constant materials (k < 3.0) have the advantage of facilitating manufacture of higher performance integrated-circuit (IC) devices with minimal increases in chip size. The reduced capacitance given by these materials permits shrinkage of spacing between metal lines to below 0.25 μm and the ability to decrease the number of levels of metal in a device. The technologies being considered for low-k applications are chemical vapor deposition (CVD) or spin-on of polymeric materials. For both types of processes, there are methods and materials capable of giving k < 3.0 dielectric stacks. This article will focus on the spin-on approach and discuss the properties of both organic and inorganic spin-on polymers.While CVD SiO2 has been the mainstay of the industry, spin-on materials are appropriate for many dielectric applications. Polyimides have applications as electrical insulators, and traditional spin-on silicates or siloxanes (k > 3.0) have served as planarizing dielectrics during the last 15 years. The newer spin-on polymers have greatly enhanced mechanical, thermal, and chemical properties, exhibiting lower dielectric constants than the traditional materials.


1999 ◽  
Vol 565 ◽  
Author(s):  
Y. Shimogaki ◽  
S. W. Lim ◽  
E. G. Loh ◽  
Y. Nakano ◽  
K. Tada ◽  
...  

AbstractLow dielectric constant F-doped silicon oxide films (SiO:F) can be prepared by adding fluorine source, like as CF4 to the conventional PECVD processes. We could obtain SiO:F films with dielectric constant as low as 2.6 from the reaction mixture of SiH4/N2 O/CF4. The structural changes of the oxides were sensitively detected by Raman spectroscopy. The three-fold ring and network structure of the silicon oxides were selectively decreased by adding fluorine into the film. These structural changes contribute to the decrease ionic polarization of the film, but it was not the major factor for the low dielectric constant. The addition of fluorine was very effective to eliminate the Si-OH in the film and the disappearance of the Si-OH was the key factor to obtain low dielectric constant. A kinetic analysis of the process was also performed to investigate the reaction mechanism. We focused on the effect of gas flow rate, i.e. the residence time of the precursors in the reactor, on growth rate and step coverage of SiO:F films. It revealed that there exists two species to form SiO:F films. One is the reactive species which contributes to increase the growth rate and the other one is the less reactive species which contributes to have uniform step coverage. The same approach was made on the PECVD process to produce low-k C:F films from C2F4, and we found ionic species is the main precursor to form C:F films.


2003 ◽  
Vol 766 ◽  
Author(s):  
Jin-Heong Yim ◽  
Jung-Bae Kim ◽  
Hyun-Dam Jeong ◽  
Yi-Yeoul Lyu ◽  
Sang Kook Mah ◽  
...  

AbstractPorous low dielectric films containing nano pores (∼20Å) with low dielectric constant (<2.2), have been prepared by using various kinds of cyclodextrin derivatives as porogenic materials. The pore structure such as pore size and interconnectivity can be controlled by changing functional groups of the cyclodextrin derivatives. We found that mechanical properties of porous low-k thin film prepared with mCSSQ (modified cyclic silsesquioxane) precursor and cyclodextrin derivatives were correlated with the pore interconnection length. The longer the interconnection length of nanopores in the thin film, the worse the mechanical properties of the thin film (such as hardness and modulus) even though the pore diameter of the films were microporous (∼2nm).


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