Process for fabricating semiconductor device with field effect transistor changeable in threshold voltage with hydrogen ion after formation of wirings
AssigneeNEC Corporation
InventorShinya Ito
Life of this patent
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Abstract
After completion of wiring strips on an inter-level insulating structure, a field effect transistor is checked to see whether or not the threshold voltage falls within a design range, if the threshold voltage is out of the design range, hydrogen ion is implanted through the inter-level insulating structure, the gate electrode and the gate insulating layer into the channel region of the field effect transistor, and the resultant semiconductor structure is annealed at 400 degrees in centigrade for 20 minutes so as to partially deactivate the dopant impurity in the channel region.
Claims24
A process for fabricating a semiconductor device, comprising the steps of:
- a) fabricating at least one MOS transistor having at least a gate insulating layer, a gate electrode, a source region, a channel region and a drain region on a semiconductor substrate;
- b) forming an inter-level insulating layer for covering at least said MOS transistor;
- c) forming contact holes in said inter-level insulating layer in such a manner that portions of said source regions and said drain regions of said MOS transistor are exposed;
- d) burying at least some of said contact holes with portions of a wiring layer;
- e) introducing hydrogen in such a manner that the hydrogen concentration is maximized in said channel region of said MOS transistor;
- and
- f) treating the resulting structure with heat,
- wherein a threshold voltage of said MOS transistor is measured after the formation of said wiring layer, and the dose of said hydrogen is determined on the basis of a difference between said threshold voltage and a target threshold voltage.
A process for fabricating a semiconductor device, comprising the steps of:
- (a) fabricating a plurality of MOS transistor and at least one monitor MOS transistor on a semiconductor substrate;
- (b) measuring a threshold voltage of said monitor MOS transistor;
- (c) determining a dose of hydrogen ion for an ion implantation process on the basis of a difference between said threshold voltage and a target threshold voltage;
- and
- (d) introducing hydrogen ion into at least one of said plurality of MOS transistors at said dose to control a threshold voltage of said at least one of said plurality of MOS transistors.
Dependencies are inferred from the claim text.