An object of the present invention is to provide a film forming material for lithography that is applicable to a wet process, and is useful for forming a photoresist underlayer film excellent in heat resistance, etching resistance, embedding properties to a supporting material having difference in level, and film flatness; and the like. The problem described above can be solved by the following film forming material for lithography. A film forming material for lithography comprising: a compound having a group of formula (0A):

##STR00001##

(In formula (0A), R.sup.A is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; and R.sup.B is an alkyl group having 1 to 4 carbon atoms.); and a compound having a group of formula (0B):

##STR00002##

A transparent polyimide film, prepared from a copolymerized polyamide acid according to a chemical cyclization method, is provided. The copolymerized polyamide acid requires at least a semi-aromatic polyamide acid, and the semi-aromatic polyamide acid is formed by reacting cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA) and 2,2-bis(trifluoromethyl)diaminodiphenyl (TFMB). The molar number of dianhydrides of the semi-aromatic polyamide acid is more than 20% of the total molar number of anhydrides of the copolymerized polyamide acid, so that the transparent polyimide film has a light transmittance greater than 80%, a chroma b* less than 5, and a CTE less than 35 ppm/ C.

An object of the present invention is to provide a novel photosensitive resin precursor that can be developed with an alkali and ring-closed even at low temperatures, and preferably has excellent thermal properties and excellent electric properties after curing, and also to provide a use application thereof. As means for achieving the object, disclosed are a bismaleimide compound comprising, in one molecule, two partial structures in each of which a carbon atom having a substituent represented by the following formula (A) (wherein Y represents a direct bond or a divalent linking group), and a carbon atom having a hydroxy group are directly bonded to each other, a polymer which is a self-polymer of the bismaleimide compound, and a benzoxazole which is an intramolecular dehydrated ring-closed product of the polymer. ##STR00001##

The present invention relates to a polyamide-imide based precursor, a polymer prepared from the precursor, an optical film comprising the polymer, and a display device comprising the optical film. A polymer according to an embodiment of the present invention comprises amide repeating units and imide repeating units that are disposed uniformly and alternately, and an optical film comprising such a polymer can exhibit excellent light transmittance, a low yellow index (Y.I), and superb stability.

The present invention provides a tetracarboxylic acid diester compound shown by the following general formula (1),

##STR00001##

wherein X.sub.1 represents a tetravalent organic group; and R.sub.1 represents a group shown by the following general formula (2),

Y.sub.1.sub.nRf).sub.k (2)

wherein the dotted line represents a bond; Y.sub.1 represents an organic group with a valency of k+1; Rf represents a linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms or an aromatic group in which a part or all of hydrogen atoms is/are substituted with a fluorine atom(s); k represents 1, 2, or 3; and n represents 0 or 1. There can be provided a tetracarboxylic acid diester compound that can give a polyimide precursor polymer soluble in a safe organic solvent widely used as a solvent of a composition, and usable as a base resin of a negative photosensitive resin composition.

The present invention aims to provide a curable resin composition capable of forming a film which, even when made thick, is less likely to crack at high temperature under a nitrogen atmosphere, a cured film formed using the curable resin composition, a stack including the cured film, an imaging device including the stack, an semiconductor device including the stack, a method for producing the stack, and a method for producing an element including a bonding electrode for use in production of the stack. Provided is a curable resin composition containing: a polyimide; and a silsesquioxane, the polyimide being contained in an amount of 0.5 parts by weight or more and 50 parts by weight or less relative to 100 parts by weight of the silsesquioxane.

The present invention aims to provide a curable resin composition that can planarize bonding surfaces and connect elements without leaving surface voids even when the elements have irregularities on the surface, thus imparting high bonding reliability between the elements, a cured film formed using the curable resin composition, a stack including the cured film, an imaging device including the stack, an semiconductor device including the stack, a method for producing the stack, and a method for producing an element including a bonding electrode for use in production of the stack. Provided is a curable resin composition containing: an organosilicon compound; and a solvent, the curable resin composition having a viscosity at 25 C. of 2,000 cP or less, the solvent being contained in an amount of 50% by weight or less in the curable resin composition, the curable resin composition having an adhesion of a score of 0 to 2 as measured by a cross-cut method in conformity with JIS K5600-5-6 using a measurement sample obtained by spin-coating a silicon wafer with the composition, evaporating the solvent, and then heat curing at 300 C. for one hour to form a film.

A modified bismaleimide resin is made by modify bismaleimide with aromatic diamine that contains fluoro substituents through chain-growth polymerization; and modified bismaleimide resin is excellent in physical properties including a low dielectric constant Dk (3 GHz) less than 3.0, a dissipation factors (3 GHz) less than 0.02, a low resin water absorptivity ranging from 0.21% to 0.33% and an excellent processability, and is particularly suited for producing a copper clad laminate that is required to have dielectric constant Dk (3 GHz) less than 3.

A polyimide which is obtained by a reaction of an aromatic diamine having a 1,1,1-trifluoro-2,2-ethanediyl group (C(CF.sub.3)H), as a linkage skeleton, with a tetracarboxylic dianhydride is easily dissolved in an organic solvent and exhibits excellent film forming properties. In addition, the thus-obtained polyimide can be used for an optical film and a display device.

The present disclosure relates to a poly(amide-imide) copolymer in which each of at least one of imide repeating units and at least one of amide repeating units is substituted with a functional group including Chemical Formula 1, ##STR00001##
wherein, R.sub.1 is hydrogen or an alkyl group having 1 to 10 carbon atoms, and L is a single bond or an alkylene having 1 to 10 carbon atoms, and a composition and a polymer film comprising the same.