Impurity diffusion agent composition and method for manufacturing semiconductor substrate

A diffusion agent composition used for diffusion of impurities into a semiconductor substrate, comprising an impurity diffusion component (A) which can be applied onto a surface of a semiconductor substrate to form a diffusion layer, and

• an organic solvent (S),
• wherein said impurity diffusion component (A) is a boron compound including a nitrogen atom, and
• wherein the boron compound is a compound represented by the following formula (a1) or the following formula (a2):
• wherein R1, R2, R3, and R4 each independently represents a hydrogen atom, a hydroxyl group, an organic group which does not contain a nitrogen atom, or a nitrogen atom-containing group;
• at least one of R1, R2, R3, and R4 is a nitrogen atom-containing group;
• and R1 and R2, R2 and R4, R3 and R4, as well as R1 and R3, may each independently be bonded to each other to form a ring, and in the formula (a2), R5, R6, and R7 each independently represents a hydrogen atom, a hydroxyl group, an organic group which does not contain a nitrogen atom, or a nitrogen atom-containing group;
• at least one of R5, R6, and R7 is a nitrogen atom-containing group;
• and two of R5, R6, and R7 may be bonded to each other to form a ring.