Method of fabricating a highly reliable gate oxide
First Claim
1. A method for forming a gate structure for a semiconductor device comprising the steps of:
- forming a hafnium layer on a semiconductor substrate by thermal evaporation at a temperature of about 150°
C. to about 200°
C.;
converting said hafnium layer to a hafnium oxide layer by oxidizing said hafnium layer; and
forming a conductive layer over said hafnium oxide layer.
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Abstract
An ultra-thin gate oxide layer of hafnium oxide (HfO2) and a method of formation are disclosed. The ultra-thin gate oxide layer of hafnium oxide (HfO2) is formed by a two-step process. A thin hafnium (Hf) film is first formed by thermal evaporation at a low substrate temperature, after which the thin hafnium film is radically oxidized using a krypton/oxygen (Kr/O2) high-density plasma to form the ultra-thin gate oxide layer of hafnium oxide (HfO2). The ultra-thin gate oxide layer of hafnium oxide (HfO2) formed by the method of the present invention is thermally stable in contact with silicon and is resistive to impurity diffusion at the HfO2/silicon interface. The formation of the ultra-thin gate oxide layer of hafnium oxide (HfO2) eliminates the need for a diffusion barrier layer, allows thickness uniformity of the field oxide on the isolation regions and, more importantly, preserves the atomically smooth surface of the silicon substrate.
466 Citations
39 Claims
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1. A method for forming a gate structure for a semiconductor device comprising the steps of:
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forming a hafnium layer on a semiconductor substrate by thermal evaporation at a temperature of about 150°
C. to about 200°
C.;
converting said hafnium layer to a hafnium oxide layer by oxidizing said hafnium layer; and
forming a conductive layer over said hafnium oxide layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of forming a memory cell comprising the steps of:
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forming at least one gate stack over a substrate, said gate stack comprising a hafnium oxide layer of about 10 Angstroms to about 100 Angstroms thick and a conductive layer over and in contact with said hafnium oxide layer, wherein said hafnium oxide layer is formed by oxidizing a hafnium layer with a high-density krypton plasma;
forming source and drain regions in said substrate on opposite sides of each of said plurality of gate stacks; and
forming a storage device connected to one of said source and drain regions. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A method of providing an oxide layer over of a surface of a silicon substrate comprising the steps of:
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thermally evaporating a hafnium layer over said surface at a temperature of about 150°
C. to about 200°
C.; and
oxidizing said hafnium layer with a high-density krypton plasma to form a hafnium oxide layer. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37)
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38. A method of forming a gate structure for a semiconductor device comprising the steps of:
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thermally evaporating a hafnium layer over a surface of a silicon substrate at a temperature of about 150°
C. to about 200°
C.;
oxidizing said hafnium layer with a high-density 3% oxygen/krypton plasma at about 400°
C. and at about 1 Torr to form a hafnium oxide layer; and
forming a conductive layer over said hafnium oxide layer.
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39. A method of providing a hafnium oxide layer having a thickness of about 10 Angstroms over of a surface of a silicon substrate comprising the steps of:
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thermally evaporating a hafnium layer over said surface at a temperature of about 150°
C. to about 200°
C.; and
oxidizing said hafnium layer with a high-density 3% oxygen/krypton plasma at about 400°
C. and at about 1 Torr to form said hafnium oxide layer.
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Specification