A Novel Low Temperature Curable Photosensitive Polybenzoxazole

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ABSTRACT:A positive-type photosensitive polybenzoxazole (PSPBO) based on a poly(o-hydroxy amide) (PHA), a dissolution inhibitor (DI) 9,9-bis(4-tert-butoxycarbonyloxyphenyl)fluorene (t-BocBHF), a thermoacid generator (TAG) isopropyl p-toluenesufonate (ITS), and a photoacid generator (PAG) (5-propylsulfonyloxyimino-5H-thiophene-2-ylidene)-(2-methylphenyl)acetonitrile (PTMA) has been developed. ITS was easily prepared by reaction of p-toluenesulfonyl chloride with isopropyl alcohol. The dissolution behavior of the PSPBO system was studied in relation to PTMA loadings, and post exposure baking (PEB) temperature and time. The PSPBO consisting of PHA (73 wt %), t-BocBHF (18 wt %), ITS (7.5 wt %), and PTMA (1.5 wt %) exhibited a sensitivity of 33 mJ/cm 2 and a contrast of 5.1 when exposed to 365 nm light (i-line) and developed with an aqueous alkaline developer, 2.38 wt % tetramethylammonium hydroxide solution (TMAHaq)/2.5 wt % iso-propanol (i-PrOH). A clear positive image with 3 mm features was produced by contact-printing and converted into a poly(benzoxazole) (PBO) pattern upon heating at 250 C for 20 min. Thus, the ITS is effective as a TAG for improving the sensitivity and low temperature cyclization of PHA into the PBO as well to meet practical requirement in the industry. 1-5 are used as buffer coatings to protect bare chips from stresses induced by fillers or thermal mismatches between a passivation layer and molding materials. These compounds possess high mechanical strength, thermal stability, and low dielectric constants. They have been developed to simplify processes in which a precursor of polybenzoxazoles (PBOs), poly(o-hydroxy amide) (PHA), is used as a polymer matrix. The phenolic hydroxyl groups in PHA promote solubility of 2.38 wt % tetramethylammonium hydroxide solution (TMAHaq), used as the aqueous alkaline developer. Previously, PHA obtained from 4,4 0 -(hexafluoroisopropylidene)bis(o-aminophenol) (6FAP) and 4,4 0 -oxybis(benzoic acid) derivatives was used because of its high transparency at a wavelength of 365 nm (i-line). A conventional PSPBO was formulated by adding the photo-sensitizer diazonaphthoquinone (DNQ) to PHA. The sensitivity of photopolymers is important in the design of photoresist materials. The conventional PSPBO based on DNQ, however, possesses low sensitivity (>100 mJ/cm 2 ) and a strong absorbance at 365 nm, and is difficult to use for thick patterns. To overcome these problems, a chemically amplified technique was introduced to develop PSPBOs coupled with a photoacid generator (PAG), 7 for which 9,9-bis(4-tert-butoxycarbonyloxyphenyl)fluorene (tBocBHF) was used as a dissolution inhibitor (DI). 8This three-component, positive-type, alkaline-developable PSPBO showed the sensitivity and contrast of 34 mJ/cm 2 and 5.8, respectively with i-line exposure, to produce a 20 mm image in 10 mm thick film. A positive image of PHA is converted into that of PBO by thermal treatment at 350 C. This high-temperature process is not applicable to conventional electronic applications containing on...

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Photosensitive Poly(benzoxazole) Based on Poly(o-hydroxy amide), Dissolution Inhibitor, Thermoacid Generator, and Photoacid Generator

Ogura

Yamaguchi

Shibasaki

et al. 2007

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“…This high transparency could be explained as arising from twisting of the polymer main chain induced by substituted groups, restricting formation of charge-transfer complexes and intramolecular hydrogen bonds. 40 …”

Section: Fluorine-free Aromatic Pha With I-line Transparency For Pspbomentioning

confidence: 99%

“…By using PTMA as an effective thermo-acid generator to lower the cyclization temperature of PHA down to 250 C, a PSPBO system was formulated, 43 where the resist film based on PHA-F (75 wt %), S-4DNQ (15 wt %), and PTMA (10 wt %) showed a photosensitivity of 60 mJ/cm 2 with i-line exposure (film thickness, 2.4 mm). A positive-tone image featuring an 8 mm line-and-space pattern was obtained, following development with 2.38 wt % TMAHaq.…”

Section: Catalysts For Low-temperature Cyclization Of Phamentioning

confidence: 99%

Recent Development of Photosensitive Polybenzoxazoles

Fukukawa

Ueda

2006

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ABSTRACT:Photosensitive polybenzoxazoles (PSPBOs) have been attracting great attention as insulating materials in microelectronic industry, and can be directly patterned to simplify processing steps. This article reviews recent works on development of PSPBOs. After brief introduction, a typical formulation method of PSPBOs was described, followed by a facile synthetic method of a precursor of PBOs, highly sensitive PSPBOs, highly transparent poly(ohydroxy amide)s (PHAs), an efficient catalyst for low-temperature cyclization of PHA, and finally other applications of PSPBOs.

“…2 Thus, the photosensitive polybenzoxazole (PSPBO) is attracting great attention as substitute for conventional PSPI in recent years. [3][4][5][6][7][8][9][10][11][12] The commercially available PSPBO is based on poly(o-hydroxy amide) (PHA), which is usually prepared by polycondensation of 4,4 0 -(hexafluoroisopropylidene)bis(o-aminophenol) (12) and 4,4 0 -oxybis-(benzoic acid) (8a) using a condensation agent, because of its high transparency at 365 nm wavelength (i-line). 13,14 There is an increasing demand for thicker films for small package to act as a buffer layer andray shielding applications, 15,16 consequently, it is quite important to develop a novel photosensitive polymer with higher transparency for UV lithography.…”

mentioning

confidence: 99%

Highly Transparent Photosensitive Polybenzoxazole: Poly(o-hydroxy amide) Derived from 4,4′-(Hexafluoroisopropylidene)bis(o-aminophenol) and o-Substituted Dicarboxylic Acid Chlorides

Shibasaki

Toyokawa

Ando

et al. 2006

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ABSTRACT:A novel poly(o-hydroxyamide) (PHA) as a precursor of photosensitive polybenzoxazole (PSPBO) that exhibits high transparency at 365 nm wavelength (i-line) has been developed. Time-dependent density functional theory (TD-DFT) calculations using the B3LYP hybrid functional were performed to predict the transparencies of various o-hydroxyamides in the i-line region. Based on these results, 2,2 0 -dimethyl-biphenyl-3,3 0 -dicarboxylic acid chloride was prepared and polymerized with 4,4 0 -(hexafluoroisopropylidene)bis(o-aminophenol). The resulting PHA-3 showed a high transparency (92%, 1:0 Â 10 À3 mol/L in N,N-dimethylacetamide (DMAc)), superior to that of the conventional PHA-1 (83% at the same concentration in DMAc) derived from 4, The thermal and dielectric characteristics of photosensitive polyimide (PSPI) are acceptable for a number of applications in the semiconductor industry, and a wide variety of PSPI has been developed and are made commercially available to meet requirements of different applications, such as inter-level insulation, stress buffer layer, and -ray shielding layers of semiconductor devices.1 PI, however, has numerous imide groups that increase water uptake and dielectric constant.2 Polybenzoxazole (PBO) is known as an super engineering thermoplastics, and its properties are comparable with PI. In addition, the absence of carbonyl group in PBO results in lower water uptake and dielectric constant.2 Thus, the photosensitive polybenzoxazole (PSPBO) is attracting great attention as substitute for conventional PSPI in recent years. 3-12The commercially available PSPBO is based on poly(o-hydroxy amide) (PHA), which is usually prepared by polycondensation of 4,4 0 -(hexafluoroisopropylidene)bis(o-aminophenol) (12) and 4,4 0 -oxybis-(benzoic acid) (8a) using a condensation agent, because of its high transparency at 365 nm wavelength (i-line). 13,14 There is an increasing demand for thicker films for small package to act as a buffer layer andray shielding applications, 15,16 consequently, it is quite important to develop a novel photosensitive polymer with higher transparency for UV lithography. The absorption of PI and PBO in i-line region corresponds to the excitation of electrons such as transitions involving p, s, and n electrons, charge-transfer (CT) electrons, and d and f electrons. Recently, we have demonstrated that the time-dependent density functional theory (TD-DFT) calculations using the B3LYP hybrid functional with the 6-311++G(d,p) basis set can well reproduce UV spectra in the measurements of model compounds without incorporation of empirical corrections.17 Utilizing this method, the absorption in i-line region of the above mentioned PHA was found to be the CT type transition between the benzoic acid and the o-hydroxyamide rings. Therefore, we designed and prepared a novel transparent PSPBO based on 4,4 0 -sulfonylbis(o-aminophenol) (13) and 4,4 0 -oxybis(benzoyl chloride) (8b) for i-line lithography.18 Introduction of a sulfone group as a substitute for hexafluoroisopropylidene...