Tailoring the surface morphology of polyimide for improved adhesion

Saraf, Ravi F.; Roldan, J.M.; Derderian, T.

doi:10.1147/rd.384.0441

Cited by 19 publications

(12 citation statements)

References 26 publications

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“…Interface chemistry effects can play a key role in adhesion strength 16–19. The atomic composition and functional groups of plasma polymers, which can be determined by using electron spectroscopy for chemical analysis (ESCA), are helpful in characterizing the interfacial chemistry between sputtered copper and plasma‐modified polyimide.…”

Section: Introductionmentioning

confidence: 99%

Nitrogen plasma modification on polyimide films for copper metallization on microelectronic flex substrates

Lin

Liu

Tsai

2005

J Polym Sci B Polym Phys

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Surface modification of polyimide films Kapton E(N) and Upilex S by nitrogen plasmas were investigated for their enhanced adhesion strength with sputtered coppers. Peel tests demonstrate this improvement, with peel strengths of 7 and 12 N/m for unmodified Kapton E(N) and Upilex S, and 1522 and 1401 N/m for nitrogen plasma‐modified Kapton E(N) and Upilex S at certain plasma conditions. Atomic force microscopy (AFM) and the sessile drop method indicated the surface roughness, and the surface energy of polyimide films were highly increased by nitrogen plasmas. This study shows the enhanced adhesion strengths of polyimide films with sputtered coppers by nitrogen plasmas, and these nitrogen plasmas were strongly affected by the surface characteristics of polyimide films. Electron spectroscopy for chemical analysis (ESCA) observed the increased surface energy on polyimide films by nitrogen plasmas was due to the increased surface composition of O and the increased chemical bond of CO. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2023–2038, 2005

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Section: Introductionmentioning

confidence: 99%

Nitrogen plasma modification on polyimide films for copper metallization on microelectronic flex substrates

Lin

Liu

Tsai

2005

J Polym Sci B Polym Phys

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“…1 It can also exhibit unusual light-emitting properties for optoelectronics applications. In many film growth techniques, rough surfaces have been systematically avoided.…”

Section: Introductionmentioning

confidence: 99%

X-ray truncation rod study of Ge(001) surface roughening by molecular beam homoepitaxial growth

Hong

Aburano

Chung

et al. 1996

Journal of Applied Physics

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Articles you may be interested inEvolution of surface roughness in epitaxial Si0.7Ge0.3(001) as a function of growth temperature (200-600°C) and Si(001) substrate miscut A new apparatus for surface xray absorption and diffraction studies using synchrotron radiation Rev.Surface roughness was determined by x-ray diffraction for Ge films on Ge͑001͒ grown by molecular beam epitaxy at room temperature. The truncation rod intensities and transverse-scan line profiles were measured as a function of perpendicular momentum transfer. Depending on the initial morphology of the surface, the same growth condition resulted in very different surface morphologies. Two types of initial surfaces were used. One was an atomically flat surface with very large terraces. The other, characterized by a roughness exponent ␣ϭ1, had a high density of steps. Deposition on the flat surfaces resulted in a fairly smooth surface, but with a graded crystalline density below the surface. Deposition on the ␣ϭ1 surfaces resulted in a more jagged surface characterized by an increase in the average height-height correlation function and a final roughness exponent of ␣ϭ1/2. Additional and complementary information about the surface structure was obtained by scanning tunneling microscopy observations.

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“…Adhesive layers of other metals such as chromium, zinc, tin, and indium have been used at the PI-electroless metal interface, and the strength of adhesion improved to several hundred N/m. [8][9][10] The use of plasma treatment to produce chemical and physical surface modifications of polymers has been widely reported. PIs have been subjected to Ar, O, N, and NH 3 plasma treatments in order to make the polymer surface more reactive toward electroless copper deposition and improve adhesion.…”

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“…ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 131.215.225 9. Downloaded on 2015-06-30 to IP…”

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Plasma Treatment and Surface Analysis of Polyimide Films for Electroless Copper Buildup Process

Bhusari

Hayden

Tanikella

et al. 2005

J. Electrochem. Soc.

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We report here a detailed characterization of the surface chemical states and morphology of polyimide ͑PI͒ films following modifications by plasma treatment and electroless copper deposition. NH 3 and Ar plasma treatments have been successfully used to achieve morphological and chemical modification of the PI surface so that electroless copper plating can occur. The adhesion strength of the electroless copper to the PI surface was measured and correlated with the plasma-induced chemical and physical modifications of the PI surface. The NH 3 plasma causes primarily chemical changes to the PI surface through creation of nitrogen moieties ͑i.e., -NvCϽ͒ on the surface. The Ar plasma treatment brings about mainly physical changes to the surface ͑i.e., surface roughening͒. The combined-plasma treatment ͑Ar plasma followed by NH 3 plasma͒ combines the desirable chemical and physical effects of each treatment, yielding a PI surface with higher roughness for physical anchoring of the copper and surface bonding sites ͑nitrogen and oxygen sites͒. During the electroless copper surface activation step with tin chloride and palladium chloride, tin bonds mainly with the oxygen on the surface, whereas palladium reacts with tin chloride as well as with the surface nitrogen. A direct relationship has been observed between surface palladium concentration and the abundance of the -NvCϽ sites on the surface. This suggests that the nitrogen radicals created during the NH 3 plasma are incorporated into the surface and serve as bonding sites for the palladium. In the subsequent electroless Cu deposition, there was a direct correlation between the palladium surface concentration and Cu coverage. The adhesion strength of the electroless copper to the PI correlated well to the surface modifications and plasma treatment conditions. For the first time, a specific bonding configuration on the PI surface is shown to promote adsorption of palladium, which in turn promotes covalent bonding with Cu. The relative importance of surface roughness and chemical bonding on the adhesion strength is discussed.Electroless metallization of advanced low-k polymers is of great interest for future high-density packaging substrates. Polyimides ͑PI͒ are an important class of polymers with desirable properties for these packaging and interconnect applications. However, PIs are difficult to activate for subsequent electroless metallization via conventional chemical "swell and etch" treatments. 1 These treatments are widely used for activating epoxy substrates and provide excellent adhesion strength between the electroless copper and the epoxy. Adhesion peel strengths on the order of 460 N/m have been reported for Cu on epoxy substrates. 2 Since the conventional swell and etch treatment has been found to be ineffective to activate the PI surface for electroless Cu deposition, several alternative surface treatments have been attempted in order to activate the PI surfaces. In work performed by Okamura et al., 3 a KOH treatment has been used to cleave the imide ring ...

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Tailoring the surface morphology of polyimide for improved adhesion

Cited by 19 publications

References 26 publications

Nitrogen plasma modification on polyimide films for copper metallization on microelectronic flex substrates

Nitrogen plasma modification on polyimide films for copper metallization on microelectronic flex substrates

X-ray truncation rod study of Ge(001) surface roughening by molecular beam homoepitaxial growth

Plasma Treatment and Surface Analysis of Polyimide Films for Electroless Copper Buildup Process

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