A patterning method includes providing a photosensitive composition on a material layer. The photosensitive composition includes one part by weight of a photo sensitive compound, 1.5 to 8 parts by weight of a resin, and 10 to 40 parts by weight of a diluent. The photosensitive compound has a chemical structure of ##STR00001##
The patterning method further includes removing the diluent in the photosensitive composition to form a photoresist layer, exposing the photoresist layer, and removing an exposed part of the photoresist layer to expose a part of the material layer.

Provided is a compound containing a phenolic hydroxy group which has excellent heat resistance, a resist composition which has excellent thermal decomposition resistance, optical sensitivity and resolution, and a composition for a resist underlayer coating which has excellent thermal decomposition resistance and dry etching resistance. The compound containing a phenolic hydroxy group has a molecular structure represented by Structural Formula (1) below: ##STR00001##
wherein R.sup.1 is a hydrogen atom, an alkyl group or an aryl group, n is an integer of 2 to 10, R.sup.2 is any one of an alkyl group, an alkoxy group, an aryl group, an aralkyl group and a halogen atom, m is an integer of 0 to 4, and when m is 2 or greater, a plurality of R.sup.2's may be the same as or different from each other and may be bonded to either one of two aromatic rings of the naphthylene skeleton.

Provided are a photosensitive resin composition which has excellent pattern processabilities (high sensitivity and high resolution) and is excellent in chemical resistance and thermal resistance after thermally treated; a heat-resistant resin or heat-resistant resin precursor used for the composition; and a diamine compound which is a raw material of the resin and the precursor. The diamine compound is a diamine compound represented by a general formula (1).

##STR00001##

A photosensitive composition for the formation of resist underlayer films that contains a novolac phenolic resin resulting from an acid-catalyzed reaction between one or more phenolic trinuclear compounds (A) selected from the group consisting of the compounds of general formula (1) and the compounds of general formula (2) and an aldehyde (B).

##STR00001##

In the formulae, R.sup.1, R.sup.2, and R.sup.3 each independently represent a substituted or unsubstituted alkyl having 1 to 8 carbon atoms, R.sup.4 represents hydrogen, substituted or unsubstituted alkyl, or substituted or unsubstituted aryl, p and q are each independently an integer of 1 to 4, r is an integer of 0 to 4, and s is 1 or 2, with the proviso that the sum of r and s is 5 or less.

A resin composition which is configured such that if the resin composition is formed into a resin composition film that has a thickness of 3.0 μm after a heat treatment at a temperature within the range of 200-350° C., the resin composition film forms a heat-resistant resin film that has a light transmittance of 50% or more at a wavelength of 365-436 nm before the heat treatment, while having a light transmittance of 10% or less at a wavelength of 365-436 nm after the heat treatment. Provided is a resin composition having a function of absorbing ultraviolet light and visible light in a short wavelength range, which is suitable for the formation of a planarization film, an insulating layer and a partition wall that are used for organic light emitting devices or display devices.

The invention provides a novolak resin having excellent properties such as heat resistance, alkali developability, photosensitivity and resolution, a photosensitive composition including the novolak resin, a curable composition including the novolak resin, a cured product thereof, and a resist material which uses the photosensitive composition or the curable composition. The novolak resin is one obtained from a compound (A) having a tris(hydroxyaryl)methine group and an aldehyde compound (B) as essential reaction ingredients. The photosensitive composition includes the novolak resin. The curable composition includes the novolak resin, and the cured product is one obtained from such a composition. The resist material uses the photosensitive composition or the curable composition.

A positive-type photosensitive resin composition includes (A) a phenol resin modified by a compound having an unsaturated hydrocarbon group having 4 to 100 carbon atoms; (B) a compound that produces an acid by light; (C) a thermal crosslinking agent; and (D) a solvent. The positive-type photosensitive resin composition according to the present invention can be developed by an alkaline aqueous solution, and an effect thereof is that a resist pattern having sufficiently high sensitivity and resolution, excellent adhesion, and good thermal shock resistance can be formed.

A modified novolak phenolic resin is obtained by reacting a novolak phenolic resin containing at least 50 wt % of p-cresol with a crosslinker. This method increases the molecular weight of the existing novolak phenolic resin containing at least 50 wt % of p-cresol to such a level that the resulting modified novolak phenolic resin has heat resistance enough for the photoresist application.

The present invention employs a compound represented by the following formula (1) and/or a resin comprising the compound as a constituent: ##STR00001## wherein R.sup.1 is a 2n-valent group of 1 to 60 carbon atoms or a single bond; R.sup.2 to R.sup.5 are each independently a linear, branched, or cyclic alkyl group of 1 to 10 carbon atoms, an aryl group of 6 to 10 carbon atoms, an alkenyl group of 2 to 10 carbon atoms, an alkoxy group of 1 to 30 carbon atoms, a halogen atom, a thiol group, a hydroxy group, or a group in which a hydrogen atom of a hydroxy group is replaced with an acid dissociation group, provided that at least one selected from R.sup.2 to R.sup.5 is a group in which a hydrogen atom of a hydroxy group is replaced with an acid dissociation group; m.sup.2 and m.sup.3 are each independently an integer of 0 to 8; m.sup.4 and m.sup.5 are each independently an integer of 0 to 9, provided that m.sup.2, m.sup.3, m.sup.4, and m.sup.5 are not 0 at the same time; n is an integer of 1 to 4; and p.sup.2 to p.sup.5 are each independently an integer of 0 to 2.

The present invention provides a photosensitive composition having excellent heat resistance, low absorbance at the exposure light at wavelengths of g-line, h-line, and i-line, and satisfactory sensitivity even when the thickness of a resist film is increased, and also provides a resist material, a coating film thereof, a novolac phenol resin suitable for these applications, and a method for producing the phenol resin. Specifically, there is provided a novolac phenol resin produced by reacting a phenolic trinuclear compound (A) with formaldehyde under an acid catalyst, the phenolic trinuclear compound (A) including a phenolic trinuclear compound (A1) produced by condensation reaction of dialkyl-substituted phenol with a hydroxyl group-containing aromatic aldehyde and a phenol trinuclear compound (A2) produced by condensation reaction of dialkyl-substituted phenol having alkyl groups at the 2- and 3-positions, 2- and 5-position, the 3- and 4-positions, or 3- and 5-positions with an aromatic aldehyde not having a hydroxyl group, wherein the molar ratio of the phenolic trinuclear compound (A1) to the phenolic trinuclear compound (A2) is 20:80 to 90:10.