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US 7,402,472 B2Granted
Method of making a nitrided gate dielectric
AssigneeFreescale Semiconductor, Inc.
InventorsSangwoo Lim, Paul A. Grudowski, Tien Ying Luo, Olubunmi O. Adetutu, Hsing H. Tseng
Life of this patent
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Abstract
A gate dielectric is treated with a nitridation step and an anneal. After this, an additional nitridation step and anneal is performed. The second nitridation and anneal results in an improvement in the relationship between gate leakage current density and current drive of the transistors that are ultimately formed.
Claims11
A method for forming a gate dielectric, comprising:
- forming a dielectric layer overlying a substrate;
- performing a first nitridation step by exposing the dielectric layer to plasma nitridation to form a plasma nitrided dielectric layer;
- forming an oxide layer at an interface between the substrate and the plasma nitrided dielectric layer by annealing, in the presence of oxygen, the nitrided dielectric layer to displace a portion of nitrogen from the interface thereby forming an atomically smoother interface;
- performing a second nitridation step by exposing the plasma nitrided dielectric layer to plasma nitridation to add more nitrogen to the plasma nitrided dielectric layer;
- and
- after the second nitridation step, annealing the plasma nitrided dielectric in the presence of oxygen layer to treat the interface between the substrate and the plasma nitrided dielectric layer by further smoothing the interface and thereby form the gate dielectric so that the interface is substantially nitrogen free;
- wherein the gate dielectric is formed without a deposition after the step of forming the dielectric layer.
4 more elements
A method for forming a gate nitrided dielectric, comprising:
- (a) forming a dielectric layer overlying a substrate and creating an oxide layer at an interface between the substrate and the dielectric layer;
- (b) exposing the dielectric layer to a plasma nitridation to form a plasma nitrided dielectric layer;
- (c) annealing the plasma nitrided dielectric layer at a predetermined temperature in the presence of oxygen;
- and
- (d) repeating steps (b) and (c) a predetermined number of times from one to one hundred to form a gate dielectric that has an interface with the substrate that is substantially nitrogen free.
2 more elements
A method for forming a transistor in and on a semiconductor, comprising:
- (a) forming a gate dielectric layer overlying a substrate, wherein the substrate comprises the semiconductor;
- (b) exposing the gate dielectric layer to a nitrogen ambient to form nitrogen in the gate dielectric layer and thereby form a nitrided gate dielectric layer;
- and
- (c) annealing the nitrided gate dielectric layer in the presence of oxygen;
- and
- repeating steps (b) and (c) a predetermined number of times to result in an interface between the nitrided gate dielectric layer and the substrate being substantially nitrogen free;
- forming a gate electrode overlying the nitrided gate dielectric layer that has a substantially nitrogen free interface with the substrate;
- and
- forming first and second current electrodes adjacent the gate electrode to provide a the transistor in and on the semiconductor.
6 more elements
Dependencies are inferred from the claim text.