Provided is a paste composition that enables the formation of a diffusion layer with a high concentration of n-type dopant element on a semiconductor substrate in a simple manner. The paste composition is intended to form a film on a semiconductor substrate. The paste composition contains an aluminum powder, a compound containing an n-type dopant element, a resin, and a solvent. The n-type dopant element is one, two, or more elements selected from the group consisting of phosphorus, antimony, arsenic, and bismuth. The content of the n-type dopant element in the n-type dopant element-containing compound is 1.5 parts by mass or more and 1000 parts by mass or less, per 100 parts by mass of aluminum contained in the aluminum powder.