Novel positive‐type photosensitive polyimide with low dielectric constant

Jin, Xing Zhou; Ishii, Hiroyuki

doi:10.1002/app.21994

Cited by 31 publications

(21 citation statements)

References 14 publications

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“…It is noted that both the sensitivity and contrast are better than existing positive tone dielectrics. 7,8 SEM micrographs of patterned films are shown in Figure 10. Since soft contact photolithography was employed, diffraction limited the minimum feature size achievable.…”

Section: Methodsmentioning

confidence: 99%

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Improved Mechanical Properties of Chemically Amplified, Positive Tone, Polynorbornene Dielectric

Mueller

Schwartz

Sutlief

et al. 2014

ECS J. Solid State Sci. Technol.

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The mechanical properties of an aqueous developed, chemically amplified, polynorbornene-based permanent dielectric have been investigated. The previously reported hexafluoroisopropanol norbornene and tert-butyl ester norbornene copolymer has been modified via two routes to improve the mechanical properties of the polymer and enable thick-film deposition. First, a third monomer, butyl norbornene (ButylNB) was added to the polymer backbone. The inclusion of 24 mol% ButylNB lowered the elastic modulus from 2.64 to 2.35 GPa and raised the dielectric constant from 2.78 to 3.48. The second approach added a low molecular weight, plasticizing additive in the copolymer formulation. Many additives were immiscible with the resin or did not affect the mechanical properties. Trimethyololpropane ethoxylate (TMPEO) was found to be a miscible additive that improved mechanical properties and could participate in crosslinking the final dielectric material. TMPEO interacted with the PAG, lowering its decomposition temperature. An optimal formulation and processing scheme were determined. A formulation with 10 pphr TMPEO was measured to have a dielectric constant of 2.94, an elastic modulus of 1.95 GPa, a sensitivity at 365 nm of 175 mJ/cm 2 , and a contrast of 4. Photo-definable, permanent, low-k dielectrics are widely used in the fabrication of microelectronic devices and packages.1-5 These dielectrics electrically isolate the interconnect and mechanically stabilize the structures for the life of the device. On integrated circuits, organic dielectrics can be used for interlayer isolation and/or the stress buffer layer on top of the device. Stress buffer layers protect the top surface of the chip and can mitigate mechanical failures that arise from a mismatch of the coefficient of thermal expansion between the chip and package during thermal cycling. In microelectronics packages, low-k dielectrics can be used in the buildup layers, electrically separating the electrical conductors. Low permittivity is critical for use in these applications, as it affects device performance, energy loss, and signal integrity.Photo-definability is an attractive property for permanent polymeric dielectrics. The ability to directly pattern the dielectric by photolithographic techniques mitigates the need for a separate photoresist and pattern transfer steps. This can lower the overall fabrication cost and reduce the number of individual process steps.2 For stress buffer and redistribution applications, positive tone photo-definable dielectrics are more desirable than negative tone ones because the lithographic mask is mostly opaque mask and less prone to transfer particle defects. Also, holes and lines in positive tone materials exhibit sloped sidewalls (opening wider at the top) which is beneficial for void-free plating of the copper interconnects. Aqueous developability is another attractive property, as it mitigates the need for environmentally harmful organic solvent developers. Further, the dielectric should exhibit high sensitivity and contrast ...

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Section: Methodsmentioning

confidence: 99%

“…These lithographic values are more than an order of magnitude better than those reported for other positive tone dielectrics. 7,8 Mechanical and electrical properties of this dielectric were also evaluated. A formulation with 60/40 mol% HFANB/TBENB exhibited a dielectric constant of 2.78 and an elastic modulus of 2.60 GPa.…”

mentioning

confidence: 99%

Improved Mechanical Properties of Chemically Amplified, Positive Tone, Polynorbornene Dielectric

Mueller

Schwartz

Sutlief

et al. 2014

ECS J. Solid State Sci. Technol.

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“…Moreover, alkaline-developable soluble polyhydroxyimides (PHIs) can be obtained by the introduction of phenolic hydroxyl groups, as reported in previous articles. 8,[12][13][14] We recently reported various photosensitive thermally stable polymers having phenolic hydroxyl groups combined with a crosslinker, 4,4 0 -methylenebis[2,6-bis(hydroxymethyl)phenol] (MBHP), and they showed very high sensitivity. [15][16][17] These findings prompted us to develop a novel photosensitive PHI [chemically amplified photosensitive polyhydroxyimide (PSPHI)] containing MBHP as the crosslinker that would provide higher sensitivity in comparison with previous PSPHIs.…”

Section: Introductionmentioning

confidence: 99%

Alkaline‐developable, chemically amplified, negative‐type photosensitive polyimide based on polyhydroxyimide, a crosslinker, and a photoacid generator

Saito

Mizoguchi

Higashihara

et al. 2009

J of Applied Polymer Sci

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A chemically amplified photosensitive polyimide based on polyhydroxyimide (PHI) from cyclobutanetetracarboxylic dianhydride and 4,4 0 -(hexafluoroisopropylidene)bis(2-aminophenol), 4,4 0 -methylenebis[2,6-bis (hydroxymethyl)phenol] (MBHP) as a crosslinker, and (5-propylsulfonyloxyimino-5H-thiophen-2-ylidene)-(2-methylphenyl)acetonitrile (PTMA) as a photoacid generator was developed to obtain the abilities of low temperature patterning, low dielectric constant, and high sensitivity. The chemically amplified photosensitive polyimide, consisting of PHI (70 wt %), MBHP (20 wt %), and PTMA (10 wt %), showed a high sensitivity (D 0.5 ) of 5.9 mJ/cm 2 and a good contrast (c 0.5 ) of 3.9, respectively, producing a clear negative-tone line-and-space pattern with 6-lm resolution. Furthermore, the chemically amplified photosensitive polyimide showed a high transparency in the i-line region and a low dielectric constant of 2.54.

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“…There is a need for thick-film, positive-tone, photosensitive dielectrics for packaging, and wafer passivation applications. 1,5,6 Positive-tone materials are better suited for interlevel dielectrics and passivation layers over substrates because lithographic masks have reduced sensitivity to particulates (dark field masks) and there is less swelling than with negative-tone systems. Positive-tone materials require fewer photochemical reactions to form vias through passivation layers.…”

Section: Introductionmentioning

confidence: 99%

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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Novel positive‐type photosensitive polyimide with low dielectric constant

Cited by 31 publications

References 14 publications

Improved Mechanical Properties of Chemically Amplified, Positive Tone, Polynorbornene Dielectric

Improved Mechanical Properties of Chemically Amplified, Positive Tone, Polynorbornene Dielectric

Alkaline‐developable, chemically amplified, negative‐type photosensitive polyimide based on polyhydroxyimide, a crosslinker, and a photoacid generator

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

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