| 摘要 |
A method for fabricating a semiconductor device is provided to decrease a protrusion part under a metal-based layer for a gate by performing an additional etch process on the metal-based layer whose lower width is greater than its upper width in etching layers for forming a gate. A semiconductor substrate(200) is prepared which has an isolation layer(201) for defining an active region. A partial thickness of both sides of the lengthwise direction of the active region is etched to step the active region. A gate insulation layer(210), a polysilicon layer(220), a metal-based layer(230) and a hard mask layer(240) are sequentially formed on the resultant structure. The hard mask layer, the metal-based layer, the polysilicon layer and the gate insulation layer are etched to form a gate on the step part of the active region. A mask layer is formed on the resultant structure to cover the gate. The mask layer formed on the substrate is etched to the height of at least the polysilicon layer to expose the sidewall of the metal-based layer whose lower width is greater than its upper width such that the metal-based layer is formed in a process for forming the gate. By using the residual mask layer as an etch barrier, the protruded lower sidewall of the metal-based layer is removed. The residual mask layer is removed. The mask layer can be a photoresist layer or an SOG(spin on glass) layer.
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