Abstract: A surface treatment agent including a compound represented by the general formula HO—P(?O)R1R2 in which R1 and R2 are each independently bonded to the phosphorus atom and are each independently a hydrogen atom, an alkyl group, a fluorinated alkyl group, or an aromatic hydrocarbon group which may have a substituent, provided that R1 and R2 are not hydrogen atoms at the same time, and an organic solvent.

Abstract: A surface treatment method for the substrate surface including two or more regions, the method including reacting a compound having the formula R1—P(?O)(OR2)(OR3), a basic nitrogen-containing compound, and the regions with each other such that a water contact angle on the metal region is greater by 10° or more with respect to a water contact angle on an insulator region close to the metal region. In compound (P-1), R1 is an alkyl group, an alkoxy group, a fluorinated alkyl group or an optionally substituted aromatic hydrocarbon group and R2 and R3 are each independently a hydrogen atom, an alkyl group, a fluorinated alkyl group or an optionally substituted aromatic hydrocarbon group.

Abstract: A surface treatment agent including a compound (P) represented by R1—P(?O) (OR2) (OR3) in which R1 is an alkyl group, an alkoxy group, a fluorinated alkyl group, or an aromatic hydrocarbon group which may have a substituent, and R2 and R3 are each independently a hydrogen atom, an alkyl group, a fluorinated alkyl group, or an aromatic hydrocarbon group which may have a substituent; a compound (S) represented by R—SH . . . in which R is an alkyl group having 3 or more carbon atoms, a fluorinated alkyl group having 3 or more carbon atoms, or an aromatic hydrocarbon group which may have a substituent; and a solvent.

Abstract: A surface treatment agent used for treating a substrate having a surface that has two or more regions made of different materials, in which at least one of the two or more regions has a metal surface, and pretreated with an oxidizing agent, the agent including a compound (P) represented by R1—P(?O)(OR2)(OR3), and an organic solvent (S) having a relative dielectric constant of 35 or less. In the formula, R1 represents an alkyl group or the like, and R2 and R3 represent a hydrogen atom or an alkyl group.

Abstract: A surface treatment agent including a compound represented by the following general formula (P-1) and an acid. In the formula, R1 represents a linear or branched alkyl group having 8 or more carbon atoms, a linear or branched fluorinated alkyl group having 8 or more carbon atoms, or an aromatic hydrocarbon group; R2 and R3 each independently represents a hydrogen atom, a linear or branched alkyl group having 8 or more carbon atoms, a linear or branched fluorinated alkyl group having 8 or more carbon atoms, or an aromatic hydrocarbon group R1—P(?O)(OR2)(OR3)??(P-1).

Abstract: A surface treatment agent used for treating a substrate which has a surface having two or more regions made of materials that are different from each other, the agent including a compound (H) represented by Formula (H-1).

Abstract: A surface treatment agent including a compound represented by the following general formula (P-1) and an acid. In the formula, R1 represents a linear or branched alkyl group having 8 or more carbon atoms, a linear or branched fluorinated alkyl group having 8 or more carbon atoms, or an aromatic hydrocarbon group; R2 and R3 each independently represents a hydrogen atom, a linear or branched alkyl group having 8 or more carbon atoms, a linear or branched fluorinated alkyl group having 8 or more carbon atoms, or an aromatic hydrocarbon group R1—P(?O)(OR2)(OR3)??(P-1).