Method of forming a transistor with a channel region in a layer of composite material
AssigneeNational Semiconductor Corporation
InventorAbdalla Aly Naem
Life of this patent
Estimating the term…
Abstract
The vertical diffusion of dopants from the gate and the bulk material into the channel region, and the lateral diffusion of dopants from the source and drain regions into the channel region resulting from thermal cycling during the fabrication of a MOS transistor is minimized by forming the source and drain regions in a layer of composite material that includes silicon, germanium, and carbon.
Claims18
A method of forming a MOS transistor on a semiconductor material of a first conductivity type, the method comprising:
- forming a layer of composite material of the first conductivity type on the semiconductor material, the layer of composite material including a first layer, a second layer that contacts a top surface of the first layer, a third layer that contacts a top surface of the second layer, and a fourth layer that contacts a top surface of the third layer, the first layer including silicon and carbon, the second layer including silicon and being substantially free of carbon, the third layer including silicon and carbon, the fourth layer including silicon and being substantially free of carbon;
- forming an insulation layer on the layer of composite material;
- forming a layer of conductive material on the insulation layer;
- etching the layer of conductive material to form a gate;
- and
- forming spaced-apart source and drain regions of a second conductivity type in the layer of composite material on opposite sides of the gate, an isolation region adjoining the semiconductor material, the isolation region having a top surface, the semiconductor material having a top surface that is substantially coplanar with the top surface of the isolation region.
A method of forming a MOS transistor on a semiconductor material of a first conductivity type, the method comprising:
- forming a layer of composite material of the first conductivity type on the semiconductor material, the layer of composite material including a first layer, a second layer that contacts a top surface of the first layer, and a third layer that contacts a top surface of the second layer, the first layer including silicon and carbon, the second layer including silicon and being substantially free of carbon, the third layer including silicon and carbon;
- forming an insulation layer on the layer of composite material;
- forming a layer of conductive material on the insulation layer;
- etching the layer of conductive material to form a gate;
- and
- forming spaced-apart source and drain regions of a second conductivity type in the layer of composite material on opposite sides of the gate.
A method of forming a MOS transistor on a semiconductor material of a first conductivity type, the method comprising:
- forming a layer of composite material of the first conductivity type on the semiconductor material, the layer of composite material including a first layer, a second layer that contacts a top surface of the first layer, and a third layer that contacts a top surface of the second layer, the first layer including silicon and carbon, the second layer including silicon and being substantially free of carbon, the third layer including silicon and carbon;
- forming an insulation layer on the layer of composite material;
- forming a layer of conductive material on the insulation layer;
- etching the layer of conductive material to form a gate;
- forming spaced-apart source and drain regions of a second conductivity type in the layer of composite material on opposite sides of the gate;
- forming a first material on a top surface of the semiconductor material before the layer of composite material is formed;
- removing a portion of the first material to expose a region of the top surface of the semiconductor material and leave a remaining portion of the first material on the top surface of the semiconductor material, the layer of composite material being formed on the top surface of the semiconductor material and surrounded by the first material;
- and
- removing the remaining portion of the first material from the top surface of the semiconductor material before the insulation layer is formed.
Dependencies are inferred from the claim text.