On a main surface of a silicon substrate of one conductivity type, a diffusion layer of the opposite conductivity type is formed, and the main surface of the silicon substrate is covered by an insulator film. The insulator film is formed with a contact hole which extends to reach the diffusion layer of the opposite conductivity type. A contact plug is provided in the contact hole. The contact plug fills the contact hole and comprises a first silicon layer of the opposite conductivity type directly connected to the diffusion layer of the opposite conductivity type, a silicon-germanium alloy layer of the opposite conductivity type directly contact to the first silicon layer, and a second silicon layer of the opposite conductivity type directly contact to the silicon-germanium alloy layer. Wiring is provided on the surface of the insulator film in direct contact to the contact plug. As a result, increase in leakage at the junction of the diffusion layer is prevented by the low-resistance contact plug including the silicon-germanium alloy.
A method of manufacturing a contact plug in a semiconductor device is disclosed. In-situ thermal doping of an impurity such as phosphorous (P) during the process by which polysilicon for a contact plug is formed by selective growth method and after in-situ doping after the growth process is employed in order to increase the concentration of the impurity in the contact plug. As a result, the disclosed method can reduce the interfacial resistance at the plug to improve the electrical characteristics of a device of more than 1 G bits.
A method for growing an epitaxial silicon-germanium layer is described. The method includes removing a native oxide layer on the silicon substrate surface. A HF vapor treatment process is then conducted on the silicon substrate. Thereafter, a germanium layer is formed on the silicon substrate, followed by performing a rapid thermal anneal process under an inert gas to form a silicon-germanium alloy layer on the surface of the silicon substrate.
A semiconductor memory device and fabrication method of same includes the processes of forming sacrifice gates on a silicon substrate with the sacrifice gates apart from each other. A first conductive layer is formed on an exposed portion of the silicon substrate between the sacrifice gates and a first inter-insulation layer is formed that exposes the first conductive layer and the sacrifice gates. The exposed sacrifice gates are removed to form openings and damascene gates are subsequently formed in the openings. Capping layers are formed on the top of the gates and a second conductive layer is formed on the exposed first conductive layer. A second inter-insulation layer is formed on the silicon substrate, and bit line contacts that expose the second conductive layer are formed by etching the second inter-insulation layer.
A semiconductor memory device and fabrication method of same includes the processes of forming sacrifice gates on a silicon substrate with the sacrifice gates apart from each other. A first conductive layer is formed on an exposed portion of the silicon substrate between the sacrifice gates and a first inter-insulation layer is formed that exposes the first conductive layer and the sacrifice gates. The exposed sacrifice gates are removed to form openings and damascene gates are subsequently formed in the openings. Capping layers are formed on the top of the gates and a second conductive layer is formed on the exposed first conductive layer. A second inter-insulation layer is formed on the silicon substrate, and bit line contacts that expose the second conductive layer are formed by etching the second inter-insulation layer.
