Method for preparing lower electrode of metal-insulator-metal semiconductor device

The invention relates to a method for preparing a lower electrode of a metal-insulator-metal semiconductor device, comprising the following steps of: providing a semiconductor substrate to form an insulation dielectric layer on the surface of the semiconductor substrate; forming a titanium liner on the surface of the insulation dielectric layer; forming a first titanium nitride layer on the surface of the titanium liner; forming a metal layer on the surface of the first titanium nitride layer by multiple steps; and forming a second titanium nitride layer on the surface of the metal layer. The preparation method disclosed by the invention is beneficial to reducing a breakdown voltage of the metal-insulator-metal semiconductor device.