A method of manufacturing a diamond substrate, a diamond substrate, and a diamond composite substrate

Method for producing a diamond substrate, by implanting ions to the main surface (11) of the diamond seed substrate (10) to form an ion implantation layer (15) to the main surface (11) of the diamond seed substrate (10) a step, by growing by vapor phase synthesis diamond growth layer (20) to the main surface (11) of the diamond seed substrate (10) after implantation of ions, a process of forming a diamond structure (30), and a step of performing heat treatment on the diamond structure (30). By performing the heat treatment, a diamond structure (30), in the ion implantation layer (15), the first structure does not include diamond growth layer (20) containing a diamond seed substrate (10) and (40), diamond It is separated into the diamond substrate comprising growing layer (20) (50). Thus, the manufacturing method capable of manufacturing a diamond substrate with a diamond substrate (50) in a short time and at low cost large area is provided.