Chemically amplified, positive tone, cross‐linkable thick‐film polymer

Mueller, Brennen K.; Kohl, Paul A.

doi:10.1002/app.39225

Cited by 2 publications

(4 citation statements)

References 17 publications

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“…The sensitivity and contrast of the chemically amplified PNB were found to be higher than the previously reported polymethacrylate polymer, which were 32.2 mJ/cm 2 and 5.2, respectively. 13 This is likely due to the higher acidity of the hexafluoroalcohol in the case of the PNB, which renders this polymer more readily dissolved in aqueous base developer.…”

Section: Resultsmentioning

confidence: 99%

“…13 The solubility switch was achieved by acid catalyzed deprotection of the tert-butyl ester to form an aqueous base soluble carboxylic acid. Formulations with 1 and 3 pphr PAG were found to have a contrast between 12.7 and 5.2, respectively.…”

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confidence: 99%

“…The functional chemistry for a chemically amplified, crosslinkable polymer has recently been demonstrated with a copolymer of tert-butyl methacrylate and 2-hydroxyethyl methacryate. 13 The solubility switch was achieved by acid catalyzed deprotection of the tert-butyl ester to form an aqueous base soluble carboxylic acid. Formulations with 1 and 3 pphr PAG were found to have a contrast between 12.7 and 5.2, respectively.…”

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confidence: 99%

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Chemically Amplified, Positive Tone, Polynorbornene Dielectric for Microelectronics Packaging

Mueller

Schwartz

Sutlief

et al. 2014

ECS J. Solid State Sci. Technol.

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A low permittivity, positive tone, polynorbornene dielectric has been developed that exhibits excellent lithographic and electrical properties. The polymer resin is a random copolymer of a norbornene hexafluoroalcohol (NBHFA) and a norbornene tert-butyl ester (NBTBE). High optical sensitivity and contrast were achieved using a chemically amplified solubility switching mechanism through the acid-catalyzed deprotection of the tert-butyl ester functionality. After developing in aqueous base, the film was thermally cured through a Fischer esterification reaction, resulting in a cross-linked permanent dielectric. The effect of the photoacid generator (PAG) concentration on the lithographic patterning and curing reactions was studied. Higher PAG loading was favorable for both sensitivity and dielectric constant. The sensitivity of a formulation was measured as low as 8.09 mJ/cm 2 . The molar ratio of the two monomers composing the polymer was varied. A higher NBHFA content was favorable because it resulted in a lower modulus, lower shrinkage, and lower dielectric constant and loss. A formulation with 70 mol% of the NBHFA had a modulus of 2.60 GPa, a 12.2% volume decrease during cure, and a dielectric constant of 2.23. The direction-dependent coefficient of thermal expansion was measured, and it was found that the anisotropy of the PNB films decreased with higher NBTBE content. Permanent dielectric materials are used in microelectronic devices and packages to separate and insulate components and interconnect. Low dielectric constant (low-k) insulators are desirable for on-chip, chip-to-chip, chip-to-package, and on-package wiring to avoid electrical delay and lower the energy consumed in the signal interconnect. [1][2][3] Polymers are widely used for these purposes because they offer a low-stress, easily processed alternative to inorganic dielectrics. [2][3][4][5] In addition, photosensitive dielectrics are desirable because they can be directly patterned by photolithographic means. Lithographically printed dielectrics do not require the use of photoresist or additional pattern transfer steps, which can be costly and expose the device to aggressive wet or dry etch process steps.Positive tone dielectrics are especially attractive because they result in sloped sidewalls that are generally favored for void-free electroplating of copper. Positive tone materials also exhibit better process yield because exposures through dark-field masks are less susceptible to particle defects. The ability to develop the latent image in an aqueous base developer mitigates the need for environmentally unfriendly organic solvent developers. High sensitivity is very important since it directly leads to higher throughput and tool utilization since less optical energy is required for the solubility switching reaction. The sensitivity of the photopatternable material is coupled to the quantum efficiency of the photoactive compound. Poor quantum efficiency often requires a high loading of the photoactive compounds to effect the inhibition or solu...

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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Chemically Amplified, Positive Tone, Polynorbornene Dielectric for Microelectronics Packaging

Mueller

Schwartz

Sutlief

et al. 2014

ECS J. Solid State Sci. Technol.

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“…Our lab has previously reported a polymer chemistry that is chemically amplified and cross-linkable (8). The proof of concept polymer was synthesized as a random copolymer of tert-butyl methacrylate and 2-hydroxyethyl methacrylate.…”

Section: Introductionmentioning

confidence: 99%

High Sensitivity, Positive Tone, Low-k Polynorbornene Dielectrics

et al. 2014

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A highly light sensitive, positive tone, low-k dielectric has been developed with excellent lithographic, mechanical, and electrical properties. The photolithographic solubility switching mechanism is based on well-studied, chemically amplified chemistry. The dielectric is composed of a polynorbornene backbone with pendent fluoroalcohol and tert-butyl ester functional groups. The effects of the photoacid generator and monomer ratio on lithographic, mechanical, and electrical properties are studied. The sensitivity (D100 = 8.09 mJ/cm2) and contrast (γ ≥ 14.2) are an order of magnitude higher than existing positive tone dielectrics. The dielectric can be cross-linked via a Fischer esterification after patterning. For one monomer composition (60% fluoroalcohol), the modulus and hardness were measured to be 2.99 GPa and 0.252 GPa, respectively. The dielectric constant for this composition was found to be 2.78.

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Chemically amplified, positive tone, cross‐linkable thick‐film polymer

Cited by 2 publications

References 17 publications

Chemically Amplified, Positive Tone, Polynorbornene Dielectric for Microelectronics Packaging

Chemically Amplified, Positive Tone, Polynorbornene Dielectric for Microelectronics Packaging

High Sensitivity, Positive Tone, Low-k Polynorbornene Dielectrics

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