Cross‐linking of aqueous base‐developable, photosensitive polynorbornene

Raeis-Zadeh, Mehrsa; Elce, Ed; Knapp, Brian; Kohl, Paul A.

doi:10.1002/app.33273

Cited by 11 publications

(24 citation statements)

References 29 publications

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“…Degradation of the crosslinking moieties and/or densification of the films is possible. 3,4 This data shows that curing and long-term exposure to temperatures at or above 220…”

Section: Resultsmentioning

confidence: 88%

“…4 Efficient polymer patterning and crosslinking with a minimal amount of invasive additives is of interest. PNB patterning was achieved via UV exposure and developing of the DNQ additive.…”

Section: Resultsmentioning

confidence: 99%

“…Negative tone PNB dielectrics have been well studied. [3][4][5][6][7] A positive tone chemistry is desirable for packaging applications, because the film is less sensitive to mask defects or particulates during exposure.Positive tone photo-definability has previously been demonstrated with a bis(diazonaphthoquinone) (DNQ) added to a polynorbornene polymer. 8 The DNQ additive in the PNB film inhibits dissolution by formation of a hydrogen bonded complex.…”

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confidence: 99%

“…3,4 Trimethylolpropane triglycidyl ether (TMPTGE) was used as the crosslinking agent with a random PNB copolymer of a fluoroalcohol norbornene and carboxylic acid norbornene, shown in Figure 1. DNQ was used as the photo active compound.…”

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confidence: 99%

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Positive Tone, Polynorbornene Dielectric Crosslinking

Schwartz

Mueller

Elce

et al. 2014

ECS J. Solid State Sci. Technol.

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The processing and properties of a positive-tone, aqueous develop, epoxy crosslinked permanent dielectric based on a polynorbornene (PNB) backbone and bis(diazonaphthoquinone) (DNQ) photosensitive compound were investigated. The developing and cure properties of the films were studied as a function of cure temperature, epoxy crosslinker loading and DNQ loading. Reduced modulus measurements showed that crosslinking of the polymer film occurred via reaction of the polymer with DNQ. The final modulus of the DNQ-crosslinked film was 4.0 GPa. Swelling measurements for a UV exposed film showed material leaching from the film. Residual solvent from swelling measurements was analysed by gel permeation chromatography which showed the indene carboxylic acid form of DNQ leached out of the polymer film. The unexposed film did not exhibit material loss through leaching. When developed, films showed a decline in modulus to 2.6 GPa, likely due to the reaction of DNQ with the aqueous base developer forming nonreactive byproducts that did not contribute to crosslinking. An epoxy crosslinker was added to the formulation which helped crosslink the polymer film by inhibiting uptake of the aqueous base during developing. The epoxy inhibition of the base uptake was confirmed by quartz crystal microbalance, where an increase in epoxy loading led to a decrease in base uptake of the film during developing. Microelectronics packaging faces a continuing challenge to accommodate scaling of electronic components to smaller size and higher performance. A higher density of electronic components requires superior dielectrics, such as in the form of photo-definable dielectrics to insulate the components electrically and mechanically support them. 1 Polynorbornene (PNB) has shown promise for use as a dielectric because of its low dielectric constant and good mechanical properties. 2The photo-definability can be achieved with a negative tone or positive tone chemistry. Negative tone materials become less soluble in a developer when exposed to UV radiation, whereas positive tone materials become more soluble in a developer when exposed to UV irradiation. Negative tone PNB dielectrics have been well studied. [3][4][5][6][7] A positive tone chemistry is desirable for packaging applications, because the film is less sensitive to mask defects or particulates during exposure.Positive tone photo-definability has previously been demonstrated with a bis(diazonaphthoquinone) (DNQ) added to a polynorbornene polymer. 8 The DNQ additive in the PNB film inhibits dissolution by formation of a hydrogen bonded complex. Ultraviolet exposure causes the DNQ to undergo the Wolff rearrangement to form an indene carboxylic acid. Unlike DNQ, the indene carboxylic acid does not extensively hydrogen bond to the PNB, leading to the solubility switch of the PNB in aqueous base.9 DNQ-based photochemistry is compatible with an aqueous developer which is more environmentally friendly than solvent-based developers.A permanent dielectric can be achieved with an epoxy-based cross...

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“…Degradation of the crosslinking moieties and/or densification of the films is possible. 3,4 This data shows that curing and long-term exposure to temperatures at or above 220…”

Section: Resultsmentioning

confidence: 88%

“…4 Efficient polymer patterning and crosslinking with a minimal amount of invasive additives is of interest. PNB patterning was achieved via UV exposure and developing of the DNQ additive.…”

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Positive Tone, Polynorbornene Dielectric Crosslinking

Schwartz

Mueller

Elce

et al. 2014

ECS J. Solid State Sci. Technol.

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High‐contrast, high‐sensitivity aqueous base‐developable polynorbornene dielectric

Raeis-Zadeh

Kohl

2012

J of Applied Polymer Sci

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The impact of multifunctional epoxy-based additives on the crosslinking, photolithographic properties, and adhesion properties of a tetramethyl ammonium hydroxide developable, polynorbornene (PNB)-based dielectric was investigated. Three different multifunctional epoxy additives were investigated: di-functional, tri-functional, and tetra-functional epoxy compounds. The tetrafunctional epoxy crosslinker enhanced the UV absorbing properties of the polymer at 365 nm wavelength. It was found that the epoxy photo-catalyst could be efficiently activated without a photosensitizer when the tetra-functional epoxy was used. The polymer mixture with additional (3 wt %) tetra-functional epoxy crosslinker and without a UV sensitizer showed improved sensitivity by a factor of 4.7 as compared to a polymer mixture containing the same number of equivalents of non-UV sensitive epoxy with a UV sensitizer. The contrast improved from 7.4 for the polymer mixture with non-UV absorbing epoxy and a UV sensitizer to 33.4 for the new formulation with 3 wt % tetra-functional epoxy and no UV sensitizer. The addition of the tetra-functional epoxy crosslinker also improved the polymer-to-substrate adhesion, which permitted longer development times, and allowed the fabrication of high-aspectratio structures. Hollow-core pillars were fabricated in 96-mm thick polymer films with a depth-to-width aspect-ratio of 14 : 1. The degree of crosslinking in the cured films was studied by nanoindentation and swelling measurements. Figure 7. Influence of 2-EP, 3-EP, and 4-EP crosslinker on swelling of crosslinked cured polymer.ARTICLE 4372

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Positive‐tone, aqueous‐developable, polynorbornene dielectric: Lithographic, and dissolution properties

Mueller

Elce

Grillo

et al. 2012

J of Applied Polymer Sci

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A positive-tone, aqueous base soluble, polynorbornene (PNB) dielectric formulation has been developed. The photolithographic solubility switching mechanism is based on diazonaphthoquinone (DNQ) inhibition of PNB resin functionalized with pendent fluoroalcohol and carboxylic acid substituents. The optical contrast (at 365 nm) was found to be 2.3. The maximum height-towidth aspect ratio of developed line and space features was 3 : 2. The sensitivity, D 100 , of a formulation containing 20 pphr of DNQ photoactive compound (PAC) was calculated to be 408 mJ cm À2 . The effects of the PAC molecule structure on miscibility and dissolution of the photosensitive films in aqueous base developer were studied. The effect of the monomer composition of the PNB polymer on the dissolution rate of the formulated PNB resin was evaluated. A unique dissolution and swelling behavior was observed. The effect is attributed to a copolymer synthesized with two monomers each of which is susceptible to deprotonation in aqueous base. FTIR measurements showed that the pure PNBFA has a small percentage of free hydroxyl groups, which did not change appreciably by the addition of PAC to the mixture.The polymers used in this study were homopolymers or copolymers of functionalized PNB monomers. 10 Functionalized monomers, a norbornene fluoroalcohol (NBFA) and a norbornene carboxylic acid (NBCBA), impart solubility in aqueous base. The NBCBA functionality also provides sites for polymer crosslinking with small-molecule, multifunctional epoxy additives.

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Cross‐linking of aqueous base‐developable, photosensitive polynorbornene

Cited by 11 publications

References 29 publications

Positive Tone, Polynorbornene Dielectric Crosslinking

Positive Tone, Polynorbornene Dielectric Crosslinking

High‐contrast, high‐sensitivity aqueous base‐developable polynorbornene dielectric

Positive‐tone, aqueous‐developable, polynorbornene dielectric: Lithographic, and dissolution properties

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