Methods of manufacturing MOSFET devices
View Patent ↗Example methods of manufacturing MOSFET devices are disclosed. One example method may include an oxidation, an etching, an ion implanting for a threshold voltage control to form an elevated source/drain region and thereby implements an ultra shallow junction.
1. A method for manufacturing a MOSFET device, the method comprising:
forming a shallow trench isolation in a substrate;
farming a first oxide layer on a surface of an active region of the substrate and implanting ions thereinto for forming a lightly doped drain in the active region prior to the formation of a gate;
forming a first nitride layer;
removing a part of the first nitride layer and the first oxide layer and etching the substrate corresponding to the part, including the tightly doped drain, by a depth of about 200 to about 1000 angstroms to define a gate region;
forming a second oxide layer aver an exposed portion of the substrate;
implanting ions into the substrate;
removing the second oxide layer;
depositing a gate insulating layer and a polysilicon layer into the removed parts of the first nitride layer and the first aid do layer;
polishing until the first nitride layer is exposed;
removing the first nitride layer, depositing an oxide layer conformally and depositing a second nitride layer;
etching the second nitride layer to form a gate sidewall;
implanting ions into the substrate to form a source and drain at locations which are deeper than that of the lightly doped drain and at sides of the gate; and
removing an exposed oxide layer.
2. A method as defined by claim 1 , wherein the substrate comprises a silicon substrate.
3. A method as defined by claim 1 , wherein the shallow trench isolation comprises an oxide layer.
4. A method as defined by claim 1 , wherein forming the second oxide layer comprises oxidizing the exposed substrate at a temperature of from about 600 to about 800° C., such that the second oxide layer has a thickness of about 100 angstroms.
5. A method as defined by claim 1 , wherein the polishing comprises chemical mechanical polishing.
6. A method as defined by claim 1 , wherein removing the second nitride layer comprises etch back processing.
7. A method for manufacturing a MOSFET device, the method comprising:
implanting ions into an active region of a substrate to form a lightly doped drain (LDD) prior to forming a gate;
forming a first nitride layer on the substrate, including the active region;
removing a part of the first nitride layer and etching to exposed substrate, including the LDD, to a predetermined depth to define a gate region;
implanting ions into the substrate to control a voltage threshold of the MOSFET device;
forming a gate insulating layer and a polysilicon layer in the gate region;
removing to first nitride layer, then depositing an oxide layer and a second nitride layer on to polysilicon layer;
etching the second nitride layer to form a gate sidewall; and
implanting ions into the substrate to form a source and drain at locations which are deeper than that of the LDD and at sides of the gate.
8. A method as defined by claim 7 , wherein the substrate comprises a silicon substrate.
9. A method as defined by claim 7 , further comprising forming a shallow trench isolation in the substrate to define the active region prior to implanting ions to form a LDD.
10. A method as defined by claim 9 , wherein the shallow trench isolation comprises an oxide layer.
11. A method as defined by claim 7 , wherein forming the polysilicon layer comprises depositing polysilicon onto the gate insulating layer in the gate region and chemical mechanical polishing the polysilicon.
12. A method as defined by claim 11 , wherein forming the gate insulating layer comprises depositing the gate insulating layer in the gate region.
13. A method as defined by claim 7 , wherein removing the second nitride layer comprises etch back processing.
14. A method as defined by claim 7 , wherein the predetermined depth is from about 200 to about 1000 angstroms.
15. A method as defined by claim 7 , further comprising, prior to implanting ions into the substrate to control the voltage threshold of the MOSFET device, forming a second oxide layer over an exposed portion of the substrate.
16. A method as defined by claim 15 , further comprising, after implanting ions into the substrate to control the voltage threshold or the MOSFET device, removing the second oxide layer.
17. A method as defined by claim 7 , further comprising, after implanting ions into the substrate to form the source and drain, removing an exposed oxide layer.