Second implanted matrix for agglomeration control and thermal stability
First Claim
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1. A method for agglomeration control at an interface of a refractory metal silicide layer and a silicon layer, comprising:
- bombarding a silicon layer over a semiconductor wafer with a first ion source to implant ions as a first diffusion barrier matrix at a predetermined depth within said silicon layer;
bombarding said silicon layer with a second ion source to implant ions as a second diffusion barrier matrix at the surface of said silicon layer;
depositing a metallization layer comprising a refractory metal above and on said silicon layer; and
heat treating said silicon layer and said metallization layer to react said metallization layer with said silicon layer so as to form a refractory metal silicide layer, said refractory metal silicide layer extending to said predetermined depth within said silicon layer so as to interface with said first diffusion barrier matrix.
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Abstract
A semiconductor device on a semiconductor wafer, wherein improvements are realized to agglomeration control, resistivity, and thermal stability of a titanium disilicide layer on a polysilicon layer. Agglomeration control is achieved through the use of two carefully selected low dose barrier diffusion matrix implants into the polysilicon layer, one of which is situated at an interface between the layer of polysilicon and the resultant layer of titanium disilicide film after heat treatment, and the other of which is near the surface of the resultant layer of titanium disilicide film after heat treatment.
33 Citations
36 Claims
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1. A method for agglomeration control at an interface of a refractory metal silicide layer and a silicon layer, comprising:
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bombarding a silicon layer over a semiconductor wafer with a first ion source to implant ions as a first diffusion barrier matrix at a predetermined depth within said silicon layer; bombarding said silicon layer with a second ion source to implant ions as a second diffusion barrier matrix at the surface of said silicon layer; depositing a metallization layer comprising a refractory metal above and on said silicon layer; and heat treating said silicon layer and said metallization layer to react said metallization layer with said silicon layer so as to form a refractory metal silicide layer, said refractory metal silicide layer extending to said predetermined depth within said silicon layer so as to interface with said first diffusion barrier matrix. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for fabricating a polysilicon gate MOS transistor structure, comprising:
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forming a device separation field oxide film on a portion of a silicon substrate of a semiconductor wafer using a field oxidation process; forming on said silicon substrate an insulating film and a silicon film above and on said insulating film; patterning said insulating film and said silicon film to form a gate insulating film and a gate above and on said gate insulating film, and to expose a portion of said silicon substrate; forming an insulating side wall spacer on lateral sides of said gate insulating film and said gate, and in contact with said silicon substrate; implanting a first diffusion barrier matrix with a first ion source within said gate at a predetermined depth; implanting a second diffusion barrier matrix with a second ion source at the surface of said gate; depositing a refractory metal film on said silicon substrate and said gate; applying a heat treatment process to said semiconductor wafer sufficient to form a refractory metal silicide film that extends down to an interface with said first diffusion barrier matrix and also extends laterally upon said silicon substrate between said side wall spacer and said device separation field oxide film; and removing substantially all of said refractory metal film on said silicon substrate and said gate that is unconverted to a refractory metal silicide film, whereby said second diffusion barrier matrix is separated from said first diffusion barrier matrix and is situated below a top surface of said refractory metal silicide film. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
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23. A method for fabricating a polysilicon gate MOS transistor structure, comprising:
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forming a device separation field oxide film on a portion of a silicon substrate of a semiconductor wafer using a field oxidation process; forming on said silicon substrate an insulating film and a silicon film above and on said insulating film; implanting a first diffusion barrier matrix with a first ion source within said silicon film at a predetermined depth; implanting a second diffusion barrier matrix with a second ion source at the surface of said silicon film; patterning said insulating film and said silicon film to form a gate insulating film and a gate above and on said gate insulating film, and to expose a portion of said silicon substrate; forming an insulating side wall spacer on lateral sides of said gate insulating film and said gate, and in contact with said silicon substrate; depositing a refractory metal film on said silicon substrate and said gate; applying a heat treatment process to said semiconductor wafer sufficient to form a refractory metal silicide film that extends down to an interface with said first diffusion barrier matrix and also extends laterally upon said silicon substrate between said side wall spacer and said device separation field oxide film; and removing substantially all of said refractory metal film on said silicon substrate and said gate that is unconverted to a refractory metal silicide film, whereby said second diffusion barrier matrix is separated from said first diffusion barrier matrix and is situated below a top surface of said refractory metal silicide film. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30)
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31. A method for forming a semiconductor device structure over a silicon substrate, said method comprising:
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providing said silicon substrate; forming a gate oxide layer over said silicon substrate, said gate oxide layer having a thickness in a range from about 50 Å
to about 150 Å
;forming a silicon layer on said gate oxide layer, said silicon layer comprising a material selected from the group consisting of monocrystalline silicon, amorphous silicon, and polysilicon, said silicon layer having a thickness in a range from about 1,000 Å
to about 2,000 Å
;implanting first ions into said silicon layer at a predetermined depth so as to form a first diffusion barrier matrix in said silicon layer, said first ions being selected from the group consisting of phosphorus ions, nitrogen ions, molybdenum ions, tungsten ions and cobalt ions, said predetermined depth being in a range from about 200 Å
to about 1,000 Å
;patterning both of said gate oxide layer and said silicon layer to form therefrom a gate structure over said silicon substrate; implanting second ions at the surface of said silicon layer so as to form a second diffusion barrier matrix in said silicon layer, said second ions being selected from the group consisting of phosphorus ions, nitrogen ions, molybdenum ions, tungsten ions and cobalt ions; and forming a metallization layer over said gate structure and on said silicon layer, said metallization layer comprising a refractory metal material selected from the group consisting of titanium, tungsten, cobalt, molybdenum, and combinations thereof. - View Dependent Claims (32, 33, 34, 35, 36)
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Specification