An Alkaline-Developable, Negative-Working Photosensitive Polybenzoxazole Based on Poly(o-hydroxyamide), a Vinyl Sulfone-Type Cross-Linker, and a Novel Photobase Generator

Abstract

An alkaline-developable, negative-working, photosensitive polybenzoxazole (PSPBO) based on poly(o-hydroxyamide) (PHA), a cross-linker 1,6-bis(vinyl sulfone)hexane (HBVS) having a flexible aliphatic chain, and N-{ [(4,5-methylenedioxy-2-R-methylnitrobenzyl)oxy]carbonyl}-2,6-dimethylpiperidine (MNCDP) as a novel photobase generator (PBG) has been developed to avoid the corrosion of copper (Cu) circuits in microchips by photogenerated acid from photoacid generators (PAGs). The resist consisting of PHA (75 wt %), HBVS (10 wt %), and MNCDP (15 wt %) showed excellent sensitivity (D 0.5 ) of 62 mJ/cm 2 and a high contrast (γ 0.5 ) of 4.1 when it was exposed to 365 nm wavelength light (i-line), postexposure baked (PEB) at 170 °C for 2 min, and developed with tetramethylammonium hydroxide aqueous solution (TMAH(aq)) at 25 °C. A fine negative pattern having 8 µm resolution on the 2.1 µm-thick film was obtained by exposure to 150 mJ/cm 2 of i-line by using a contact-printed mode. The resulting polymer film cured at 350 °C in an air atmosphere had a low dielectric constant (ε: 2.78), high thermal stability, good mechanical properties, and low water absorption, all of which properties were comparable to those of PBO film. This novel patterning system with both a new PBG and crosslinker can be one of the candidates for the next generation microchips fabrication process which avoids corrosion of Cu circuits in semiconductor devices.

Low‐CTE photosensitive polyimide based on semialicyclic poly(amic acid) and photobase generator

“…A dielectric constant (ε) is one of the important properties of PSPIs as insulator materials. The ε of polymer film at 10 MHz is calculated from the average refractive index ( n AV ) of the film according to a modification of Maxwell's equation, ε = 1.1 n 31. The PAA and PSPI solutions were spin‐casted on a quartz plate, and the films were imidized by heating.…”

“…MHz is calculated from the average refractive index (n AV ) of the film according to a modification of Maxwell's equation, e ¼ 1.1 n 2 AV . 31 The PAA and PSPI solutions were spin-casted on a quartz plate, and the films were imidized by heating. Table 3 shows the refractive indices and the optically estimated e values of the PI and PSPI films.…”

Development of Thermally Stable and Photosensitive Polymers

“…An alkaline-developable, negative-working photosensitive polybenzoxazole based on poly(ohydroxyamide), a vinyl sulfone-type cross-linker, and a novel photobase generator [21] 10 µm Figure 6. SEM image of PBO pattern cured at 250℃ for 20 min under nitrogen.…”

Photoresist materials comprising photobase generators and epoxy resins bearing carboxylic acids to lead to marked enhancement of base‐catalyzed cross‐linking reactions

“…However, there is a drawback, in that the acidic species from PAGs will induce corrosion in next‐generation microchips. One of the approaches to overcome this problem is the use of photobase generators (PBGs), which generate base catalysts . Although photosensitive materials based on base‐catalyzed reactions have merit in preventing erosion of metallic substrates, PBGs generally have lower quantum yields than PAGs .…”