Pyromellitic Dianhydride-oxydianiline Research Articles

Changes in the Peeled Surfaces of Copper Thin Films Deposited on Polyimide Substrates After Heat Treatment

Peel strength between a copper (Cu) thin film and a polyimide (pyromellitic dianhydride-oxydianiline, or PMDA-ODA) substrate is reduced by heat treatment at 150°C in air. In this work, we investigated the peel strength, the morphology of the interface between Cu films and polyimide substrates using optical microscopy and electron microscopy, and chemical change of the interface using Auger electron spectroscopy (AES) and micro X-ray photoelectron spectroscopy (XPS). The analysis showed that CuO “lumps” were present on the peeled surface of PMDA-ODA after heat treatment at 150°C in air. The peeled surfaces of other polyimide substrates were also analyzed: biphenyl dianhydride-para phenylene diamine (BPDA-PDA) and biphenyl dianhydride-oxydianiline (BPDA-ODA). CuO lumps were present on the peeled surface of BPDA-ODA after the heat treatment, but not that of BPDA-PDA. Compared with the adhesion strength for the Cu thin film, the adhesion strength was high for the Cu/PMDA-ODA and Cu/BPDA-ODA laminates, but the adhesion strength was very low for the Cu/BPDA-PDA laminate. This low strength is the reason that CuO lumps were not detected on the peeled surface of the BPDA-PDA substrate. These CuO lumps were related to the adhesion degradation of the Cu/polyimide laminates after the heat treatment.

Changes in the adhesion strength between copper thin films and polyimide substrates after heat treatment

The adhesion strength between a copper (Cu) thin film and a polyimide [pyromellitic dianhydride-oxydianiline (PMDA-ODA)] substrate is reduced by heat treatment at 150°C in air. In this work, we determined the changes in adhesion strength between Cu films and polyimide substrates using Auger electron spectroscopy (AES), attenuated total reflection Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The analysis showed that the weak boundary layer (WBL) shifted towards the Cu interface as the heat treatment time was increased. To confirm this shift, we looked at two other polyimide substrates: biphenyl dianhydride-p-phenylene diamine (BPDA-PDA) and biphenyl dianhydride-oxydianiline (BPDA-ODA). Comparing the adhesion strength for the Cu thin film, the adhesion strength was high for the Cu/PMDA-ODA and Cu/BPDA-ODA laminates, but very low for the Cu/BPDA-PDA laminate. One of the possible reasons for this behavior could be that the ether moiety between the two benzene rings in ODA is related to the adhesion between a Cu film and an 02-plasma-treated polyimide (PI) substrate. The relationship between the adhesion strength and chemical bonding states is also discussed. We conclude that a Cu thin film sputtered onto a PI substrate is apt to peel at the oxidized interface, due to the heat treatment.

The polyimide (PMDA-ODA) titanium interface. Part 3. A theoretical study

Ab initio SCF calculations are used to determine the possible interaction sites in model structures of the polyimide pyromellitic dianhydride-oxydianiline (PMDA-ODA) interacting with Ti atoms. The results are compared with the observed XPS spectra. Several sites of interaction for one or two atoms of Ti with model molecules have been investigated. It is shown that for one interacting Ti a favorable structure corresponds to the formation of a π-complex between Ti and the aromatic ring of the PMDA unit. Other possible sites are, the center of one heterocycle of PMDA, one >C=O group of PMDA and one aromatic ring of ODA. When two Ti atoms interact with PMDA-ODA with the first atom located over the aromatic ring of PMDA, then the possible sites of interaction for the second atom are, one aromatic ring of ODA, one >C=O group of PMDA and one heterocycle of PMDA. Calculated Koopmans' ionization energies, for two Ti atoms located at their most stable positions, reproduce the main features of the XPS spectra of the Ti/polyimide system except for the low energy C1s peak observed at about 282 eV. Our calculations confirm that this peak can be assigned to a carbide bond between one carbon and a Ti atom.

Effect of polyimide processing on multichip glass ceramic module fabrications

This paper discusses the yield analysis of the thin film wiring layers fabricated on the 127 mm multichip glass ceramic modules (MCM-D), currently used on the IBM Enterprise System/9000 family of computer processors. To select a suitable polyimide (PI) for the thin film wiring layer, modules were fabricated with either the 3,3',4,4'-benzophenone tetracarboxylic dianhydride-1,3-bis(3-aminophenoxy)benzene (BTDA-APB) or the pyromellitic dianhydride-oxydianiline (PMDA-ODA) polyimide. By keeping all other processing parameters and structures the same, the wiring layers fabricated with the PMDA-ODA polyimide exhibited significantly better yield than those made of the BTDA-APB PI. The yield loss in the modules fabricated with the BTDA-APB PI occurred during thermal processing, where some of the transmission lines fabricated atop the PI were found cracked. Further investigations indicate that, during lift-off processing, the presence of a small contaminant, such as a fiber, metal flake, a particle, or polishing scratches can expose the PI to the hot N-methylpyrollidinone (NMP) solvent. Depending on the polyimide used for thin film processing, the diffusion and swelling of the PI by the low molecular weight organic solvent can potentially produce significant damage to the polyimide/Cu wiring structure and the consequent yield loss of the modules due to line opens. The magnitude of the damage was found to depend on the rate of solvent diffusion, process temperature, lift-off time and the amount of PI swelling during processing. To understand these important process parameters in detail, in-plan solvent diffusion and PI swelling in the PMDA-ODA and BTDA-APB films were quantitatively measured. It was found that the rate of in-plane (X-Y plane) solvent diffusion in BTDA-APB is D=0.0617 /spl times/ex-(-9.4 Kcal/RT) cm/sup 2//s versus D=0.00155/spl times/exp(-10.24 Kcal/RT) cm/sup 2//s for the PMDA-ODA film. Both types of PI films were fully imidized at 375/spl deg/C in nitrogen for 1 h. Thus, the rate of lateral diffusion of NMP in BTDA-APB is approximately 150 times faster than that of the PMDA-ODA film at 85/spl deg/C. Furthermore, the swelling of PMDA-ODA PI in the 85/spl deg/C NMP bath is 45% versus 82% for the BTDA-APB PI. The poor elongation property of the BTDA-APB film (strain at break /spl sim/4-7% versus 90-130% for the PMDA-ODA PI) further aggravated the solvent problem, BTDA-APB was always found cracked or crazed after being exposed to the NMP solvent, making it very vulnerable to the lift-off process. Consequently, by selecting the PMDA-ODA polyimide for module manufacturing, along with an improved clean room manufacturing facility, the glass ceramic MCM-D has become an extremely reliable product with excellent manufacturing yield.

加熱によるポリイミド銅積層体の剥離強度変化

The adhesive strength between Cu thin films and polyimide (pyromellitic dianhydride-oxydianiline) substrates is known to be reduced after heat treatment at 150°C in air. In order to investigatethe interface between the Cu thin film and polyimide substrate, optical microscopic observations, electron microscopic observations, AES analysis, FT-IR analysis, and XPS analysis were performed. The weak boundary layer (WBL) is found to move toward the Cu interface as the heat treatment proceeds. Observation of the peeled surfaces after heat treatment shows that Cu or Cu2O particles are present on the polyimide surface. The relationship between the adhesive strength and the chemical bonding states is also discussed.

Fabrication of New Multilayer Heterostructures Based on Self-Assembled Layers of Poly(amic acid) with Various Electroactive Polymers

ABSTRACTSelf-assembled films of pyromellitic dianhydride oxydianiline (PMDA-ODA) were fabricated through the alternate adsorption of poly(amic acid) and various polycations including poly(allyl amine) (PAH), polyaniline (PAni), and the tetrahydrothiophene precursor of poly(p-phenylene vinylene) (PPV). In all cases, a linear build-up in thickness with increasing number of bilayers was observed with a high sensitivity of the average bilayer thickness to the ionic strength of the poly(amic acid) solution. By controlling the ionic strength of the PAA solution, the bilayer thickness could be varied from 10 to 100 Å, depending on the polycation used. Examination of the self-assembled films of poly(amic acid) and PAni showed that a conductivity of 0.5 S/cm could be achieved prior to conversion of the polyimide, but that the conductivity was drastically reduced when either the ionic strength of the poly(amic acid) solution was increased or when the poly(amic acid) was converted to polyimide. The self-assembly of poly(amic acid) with precursor PPV demonstrated that it was possible to produce a film which can be self-assembled as two ionic precursor polymers and then thermally converted into a film composed of two non- ionic polymers. Advancing sessile water drop contact angle measurements revealed that very hydrophobic surfaces can be generated upon conversion of the PAA/precursor PPV films.

Thermal And Mechanical Properties Of Polyimide Films

AbstractIn recent years, polyimide film has become a commonly used insulator for microelectronic devices including advanced semiconductor chip and high density packaging. It has the advantages of low dielectric constant, thermal stability and low processing cost. In general, it is important to understand both the thermal and mechanical properties of a microelectronic material. Thermal and mechanical properties play very important roles in terms of determining the device structural integrity. Mismatch of material properties could cause feasibility and reliability problems. These properties are also essential for mechanical stress and thermal stress modeling studies. Biphenyldianhydride-Phenylenediamine (BPDA-PDA) and Pyromellitic Dianhydride-Oxydianiline (PMDA-ODA) are two commonly used polyimide films in electronic industry. Their thermal expansion coefficients and mechanical properties were studied and reported here.

Physical and Spectroscopic Studies of the Nucleation and Growth of Copper Thin Films on Polyimide Surfaces by Chemical Vapor Deposition

The chemical vapor deposition (CVD) of copper from (hexafluoroacetylacetonate)(vinyltrimethylsilane)-copper(I) [Cu[sup I](hfac)(vtms)] and the thermal evaporation of copper on pyromellitic dianhydride-oxydianiline (PMDA-ODA) polyimide have been studied with a variety of techniques including reflection absorption infrared spectroscopy (RAIRS), ellipsometry, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). Our studies reveal that the nucleation and growth of Cu by CVD occurs by the preferential reaction of surface carbonyl groups, (C=O)[sub a], of PMDA-ODA with the CVD reagent. Preferential trapping of thermally deposited metal atoms also has been seen, although the nucleation processes appear to be less chemically specific than is seen in CVD growth on this substrate. Carbonyl groups at the surface of the polyimide react with the precursor molecules at 300 K, although the reactive sticking probabilities appear to be low ([much lt]10[sup [minus]3]). The facility of nucleation on the polyimide surface depends on both the number and orientation of the carbony groups on the polymer surface which, in turn, depends sensitively on the thickness of the film. The nucleation of Cu growth from Cu[sup I](hfac)(vtms) is found to proceed from surface reactions mediated by these surface groups. 63 refs., 19 figs., 2 tabs.

Formation of polyimide- Cu complexes: improvement of direct Cu-on-PI and PI-on-Cu adhesion

Polyimides containing triazole or imidazole functionalities have been synthesized. Poly(3,3',4,4'-benzophenone tetracarboxylic dianhydride-3,5-diamino-1,2,4-triazole) (BTDA-TADA) contains triazole groups as repeat units and poly(4,4'-oxydiphthalic anhydride-1,3-aminophenoxybenzene-8-azaadenine) (ODPA-APB-8-azaadenine) consists of triazole (8-azaadenine) groups as the end caps. While the BTDA-TADA polyimide starts to decompose at 350°C, the ODPA-APB-8-azaadenine polyimide is thermally stable at 400°C. The peel strength of copper to BTDA-TADA polyimide without surface modification is 200-400 J/m2. For the adhesion of polyimide to copper, ODPA-APB-8-azaadenine polyisoimide (1.0 μm) and poly(pyromellitic dianhydride-oxydianiline) (20 μm) were coated onto the copper substrate and then the two layers were cured together to polyimides at 400°C. Peel strengths of 500-800 J/m2 were obtained. The failure of the copper/polyimide interface by peeling either the copper or the polymer layer occurred in the near-interfa...

Fracture of metal-polymer line structures. II. Rigid-rodlike polyimide

The fracture behavior of the Au/Cr line structures formed on a rigid-rodlike polyimide, biphenylenetetracarboxylic dianhydride-phenylenediamine (BPDA-PDA), film substrate has been investigated using a stretch deformation technique and compared with that of the Au/Cr line structures formed on a semiflexible polyimide, pyromellitic dianhydride-oxydianiline. In general, the effects of metal line dimensions on the deformation behavior can be attributed to the changes in the mechanical environment induced by metal confinement at the line interface. This gives rise to a fracture behavior and geometrical dependence of these two polyimide structures which are qualitatively similar in most aspects. However, the fracture energy and crack propagation rate of these two polyimide line structures are quantitatively different, with values about twice higher for the BPDA-PDA line structures. This cannot be accounted for solely by the different chemical bonding; instead, the high fracture toughness of the BPDA-PDA structure has to be attributed to its superior mechanical properties, particularly its plastic deformation characteristics, which are related to its molecular structure.

Fracture of metal-polymer line structures. I. Semiflexible polyimide

The fracture characteristics of metal/polymer line structures formed by depositing Au/Cr lines on a semiflexible polyimide, pyromellitic dianhydride-oxydianiline (PMDA-ODA), substrate have been investigated using a stretch deformation technique. The delamination behavior, fracture morphology, fracture energy, and energy dissipation rate have been determined as a function of line width and thickness. The metal dimension was found to influence the crack formation mode and morphology. The experimental studies were supplemented by finite-element analysis to evaluate the stress distribution and deformation energetics of the line structure, which takes into account the plastic deformation of the metal and the polymer. Results from this analysis show that the observed fracture characteristics can be attributed to the edge and thickness effects induced by metal confinement. Essentially, the deformation behavior is determined by the mechanical environment induced by metal confinement at the interface. Plastic deformation of both metal and polymer plays an important role in controlling the stress distributions as well as the deformation energetics. The fracture energy of the metal-polyimide interface determined by an overall energy balance method was consistent with that obtained from energy dissipation rate. The average value is 25 J/m2 for the Au/Cr/PMDA-ODA line structure.

Chemical evaluation of Cu–polyimide interfaces

The interactions of copper overlayers with four different polyimides [pyromellitic dianhydride–oxydianiline (PMDA–ODA), benzophenonetetracarboxylic dianhydride–diaminobenzophenone (BTDA–DABP); oxydiphthalic anhydride–oxydianiline (ODPA–ODA); and pyromellitic dianhydride–phenylene diamine (PMDA–PDA)] have been studied by x-ray photoelectron spectroscopy. Emergent etherlike functionalities on polyimides without innate ether groups suggest a copper-induced partial reduction of carbonyl groups. A surface behavior diagram of the carbon chemistry confirms this reaction by indicating a partial conversion of carbonyl moieties to etherlike moieties.

Solvent and isomer effects on the imidization of pyromellitic dianhydride-oxydianiline-based poly(amic ethyl ester)s

The imidization behaviour of the isomeric poly(amic ethyl ester) (PAE) precursor molecules of the polyimide pyromellitic dianhydride—oxydianiline was followed using forward recoil spectrometry. The degree of imidization after 1 h at various temperatures was found to depend strongly on the spin-casting solvent. Films cast from dimethyl sulfoxide (DMSO) showed an imide fraction, f, which was independent of depth and of isomeric precursor (i.e. whether the precursor was para-PAE, meta-PAE or a random mixture of meta and para (mixed-PAE).) In films spun cast from N-methylpyrrolidone (NMP), however, fs for the para- and mixed-PAE were larger than that for the meta-PAE. In addition the fs for the para-PAE and mixed-PAE were found to be greater for films cast from NMP than from DMSO for any given thermal treatment. For the meta-PAE, f was independent of the casting solvent. Over an imidization temperature range of 180–280°C f was found to vary with depth, being lower than the bulk value over the first 3000 Å from the film surface. These observations appear to be related to a retention of the NMP with f being larger where NMP is retained.

Observation of nanometer ordering in multilayer films of pyromellitic dianhydride–oxydianiline using the scanning tunneling microscope and ultrahigh vacuum

We have obtained topographic images and spatially resolved spectroscopic information of uncoated pyromellitic dianhydride–oxydianiline (PMDA-ODA) films. We find that prolonged exposure to vacuum is a key to successful imaging of this nominally insulating film surface. It is postulated that water desorption from the film is responsible. This mechanism may apply to many other organic materials. Topographic results indicate that there is a fair amount of ordering in this polymer, at least for dip-coated films. Finally, we see that PMDA-ODA has low-density states very close to the pseudo-Fermi energy, in contrast to the wide band gap predicted by ultraviolet photoelectron spectroscopy results. This provides an explanation for the anomalous conductivity seen in these thin films.

Structural characterization of an ordered aromatic polyimide: pyromellitic dianhydride-oxydianiline

The three-dimensional (3-D) ordered structure of semiflexible pyromellitic dianhydride oxydianiline (PMDA-ODA) is calculated using the CHARMM molecular modeling program. Polymorphism in the ordered chain conformational is calculated with chain periodicities n= 2,3, and 4, where n is the number of monomers within the period. A planar zigzag chain cross-section is observed in the n= 2 and 4 structures while a triangular cross-section is observed in the n= 3 structure. The optimum ordered chains are packed to form a 3-D crystal by consitering relative chain translations parallel and perpendicular to the chain axis by adjusting the number of basis chains, m in the unit cell

Grazing incidence x-ray scattering studies of thin films of an aromatic polyimide

Grazing incidence X-ray scattering measurement of the near surface structure of poly(pyromellitic dianhydride-oxydianiline) (PMDA-ODA) are reported. The structure parallel to the film surface was investigated as a function of thermal treatment and film thickness. The PMDA-ODA structure was studied as a function of the X-ray penetration depth. For thick films (≃2500 A), it was found that near the air surface the PMDA-ODA was more ordered than in the bulk of the specimen, and for thermal treatment above 300°C, a crystalline-like ordering was observed; In the near surface region the PMDA-ODA molecules locally assumed a more planar zigzag conformation. However, the interchain packing, i.e. the coherence of order normal to the chain axis was markedly improved

X-ray photoelectron spectroscopic studies of chemical vapor deposition with TaF5 precursor on polyimide surfaces

Chemical vapor deposition of Ta on the polyimide pyromellitic dianhydride oxydianiline was attempted using TaF5 as the precursor. The deposition temperature was 350 °C. Photoelectron spectroscopy measurements show that Ta is bound in a high oxidation state. Our data show strong evidence that initially the ternary compound TaOF3 is formed on polyimide in a first step. The carbonyl group is the main reactive site upon TaF5 exposure. It has to be noted that no passivation of the surface takes place and that there is no limit for film thickness. At very high doses, however, the film concentration at the surface is suggestive for the stable compound TaO2F. This observation is explained in terms of the formation of a metastable TaOF3 compound in the first stages of film growth and a phase transformation to TaO2F at larger thicknesses. Annealing experiments to 500 °C suggest the transformation to the oxide Ta2O5 that is strongly related to the almost complete loss of fluorine from the film upon heating.

Interaction of polyamic acids and polyamic esters with copper and substituted polysilsesquioxane copolymers

AbstractThe interactions of biphenyldianhydride–p‐phenylenediamine (BPDA–PDA) polyamic acid and ester polymers with copper and copper‐treated surfaces containing polysilsesquioxanes formed from 3‐aminopropyltriethoxysilane (APS) (or copolymers of APS and phenyltriethoxysilane) were compared by grazing‐incidence infrared spectroscopy. This investigation of a flexible dianhydride–stiff diamine copolymer compliments earlier work using the stiff dianhydride–flexible diamine polyamic acid and ester of pyromellitic dianhydride–oxydianiline (PMDA–ODA). Results support earlier findings that amic acids form thermally labile salts on copper but esters do not. Further, while APS forms a copper‐interactive film that insulates amic acid/metal interaction, APS–phenylsilsesquioxane copolymers create an interfacial region interactive with both copper and overlying polyamic acid.

The use of peel tests to examine the self adhesion of polyimide films

Peel tests were used to examine the adhesion between two layers of the polyimide pyromellitic dianhydride-oxydianiline (PMDA ODA). The main thrust of this work was to examine these tests with particular emphasis on yielding in bending of the peeled strips. Two peel geometries and a range of sample thicknesses were used to study interfaces whose strength could be varied over a wide range by changing the cure schedule. The peel strength varied with strip thickness and often reached a peak at an intermediate thickness. The results were shown to agree qualitatively with a combination of two theoretical models for the effects of yielding on peel tests. It was also found that a second problem of polyimide adhesion, the effect of solvent swelling, could significantly enhance the adhesion between polyimide layers.

Interaction of evaporated copper with vapor-deposited thin polyimide films

The interaction of evaporated copper deposits with vapor-deposited, vacuum-cured thin films of pyromellitic dianhydride-oxydianiline (PMDA-ODA) polyimide was studied using x-ray photoelectron spectroscopy (XPS) and Fourier transform infrared reflection absorption spectroscopy (FTIRAS). XPS and FTIRAS measurements indicate a preferential interaction of the copper with the imide part of the molecule, some interaction with the ODA ether oxygen and only a very weak interaction with the phenyl rings. The spectral changes observed show a dependence on the rate of the copper deposition.