Method for forming mosfet
AssigneeUnited Microelectronics Corp.
InventorChuan-Fu Wang
Life of this patent
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Abstract
A method for forming a MOSFET is described. The feature of this invention is that an epitaxial silicon layer with device isolation structures is formed over a substrate, wherein each device isolation structure is made of oxide. The invention need not etch the substrate for forming a device isolation structure. As a result, the invention not only prevents stress and dislocation generation and avoids leakage current, but also provides an easily method for forming a device isolation structure.
Claims14
A method for forming a MOSFET, comprising the steps of:
- providing a substrate;
- forming a mask layer having an opening to expose the substrate;
- filling the opening with an epitaxial silicon layer, wherein a surface level of the epitaxial silicon layer is substantially the same as that of the mask layer;
- after filling the opening with the epetaxial silicon layer, removing the entire mask layer to expose the substrate;
- forming an oxide layer on the exposed substrate, wherein a surface level of the oxide layer is substantially the same as that of the epitaxial silicon layer;
- and
- forming a gate on the epitaxial silicon layer and source/drain regions in the epitaxial silicon layer.
A method for forming a MOSFET, comprising the steps of:
- forming a pad oxide layer and a silicon nitride layer on a substrate in sequence;
- forming an opening in the silicon nitride layer and the pad oxide layer to expose a portion of the substrate;
- filling the opening with an epitaxial silicon layer, wherein a surface level of the epitaxial silicon layer is substantially the same as that of the silicon nitride layer;
- after filling the opening with an epitaxial silicon layer, removing the entire silicon nitride layer to expose the pad oxide layer;
- forming an oxide layer over the substrate;
- planarizing the oxide layer to expose the epitaxial silicon layer;
- and
- forming a gate on the epitaxial silicon layer and source/drain regions in the epitaxial silicon layer.
A method for forming a device isolation structure, comprising the steps of:
- forming a mask layer with an opening on a substrate to expose a portion of the substrate;
- filling the opening with an epitaxial silicon layer, wherein a surface level of the epitaxial silicon layer is substantially the same as that of the mask layer;
- removing the mask layer to expose the substrate;
- and
- forming an oxide layer on the substrate, wherein a surface level of the oxide layer is substantially the same as that of the epitaxial silicon layer.
Dependencies are inferred from the claim text.