FinFET structure using differing gate dielectric materials and gate electrode materials

A semiconductor structure includes a first finFET and a second finFET. The first finFET and the second finFET may comprise an n-finFET and a p-finFET to provide a CMOS finFET structure. Within the semiconductor structure, at least one of: (1) a first gate dielectric within the first finFET and a second gate dielectric within the second finFET comprise different gate dielectric materials; and/or (2) a first gate electrode within the first finFET and a second gate electrode within the second finFET comprise different gate electrode materials.

BACKGROUND

1. Field of the Invention

The invention relates generally to finFET structures. More particularly, the invention relates to finFET structures with enhanced performance.

2. Description of the Related Art

Semiconductor structures include both passive semiconductor devices such as resistors and capacitors, as well as active devices such as transistors and diodes. Field effect transistor devices are common transistor devices within semiconductor structures. Field effect transistor devices are often fabricated in complementary pairs to provide complementary metal oxide semiconductor (CMOS) structures. CMOS structures and CMOS devices are desirable insofar as CMOS structures and CMOS devices generally consume less power than other transistor structures and transistor devices.

Field effect transistor structure and device dimensions have been scaled effectively to increasingly smaller dimensions over the period of several decades. While such scaling is projected to continue, nonetheless field effect transistor performance improvements as a function of field effect transistor scaling are becoming more difficult to achieve. To that end, materials of construction of field effect transistors are now often routinely selected and controlled in an effort to provide additional avenues to enhance field effect transistor performance.

Various field effect transistor structures having desirable properties, including in particular CMOS structures, are known in the semiconductor fabrication art.

For example, Lee et al., in U.S. Pat. No. 6,653,698, teaches a CMOS structure that provides individual n-FET and p-FET devices having individual work functions. To realize such a CMOS structure, the individual n-FET and p-FET gate electrodes are fabricated at least in part from different metal gate materials.

In addition, Polischuk et al., in U.S. Pat. No. 6,794,234, also teaches a CMOS structure that provides individual n-FET and p-FET devices having individual work functions. To realize such as CMOS structure, the individual n-FET and p-FET gate electrodes are fabricated at least in part from different interdiffused metal gate materials.

Semiconductor device and semiconductor structure dimensions are certain to continue to decrease as semiconductor technology advances. Thus, desirable are novel semiconductor devices and semiconductor structures, including in particular CMOS devices and CMOS structures, that provide for enhanced performance.

SUMMARY

The invention provides a semiconductor structure and a method for fabricating the semiconductor structure. The semiconductor structure includes in particular a first finFET structure and a second finFET structure that in an aggregate may comprise a CMOS finFET structure. Within the semiconductor structure in accordance with the invention with respect to the first finFET structure and the second finFET structure, the first finFET structure and the second finFET structure are fabricated using at least one, and preferably both, of a different gate dielectric material and a different gate electrode material (i.e., a different gate dielectric material and/or a different gate electrode material).

A particular semiconductor structure in accordance with the invention includes a first finFET that includes a first semiconductor fin located over a substrate, a first gate dielectric located upon the first semiconductor fin and a first gate electrode located to straddle the first semiconductor fin to provide a first channel region beneath the first gate electrode that separates a plurality of source and drain regions within the first semiconductor fin. This particular semiconductor structure also includes a second finFET that includes a second semiconductor fin located over the substrate, a second gate dielectric located upon the second semiconductor fin and a second gate electrode located to straddle the second semiconductor fin to provide a second channel region beneath the second gate electrode that separates a plurality of source and drain regions within the second semiconductor fin. Within this particular semiconductor structure, at least either: (1) the first gate dielectric and the second gate dielectric comprise different gate dielectric materials; or (2) the first gate electrode and the second gate electrode comprise different gate electrode materials.

A particular method for fabricating a semiconductor structure in accordance with the invention includes forming over a substrate a first finFET that includes a first semiconductor fin formed over the substrate, a first gate dielectric formed upon the first semiconductor fin and a first gate electrode formed to straddle the first semiconductor fin to provide a first channel region beneath the first gate electrode that separates a plurality of source and drain regions within the first semiconductor fin. This particular method also includes forming over the substrate a second finFET that includes a second semiconductor fin formed over the substrate, a second gate dielectric formed upon the second semiconductor fin and a second gate electrode formed to straddle the second semiconductor fin to provide a second channel region beneath the second gate electrode that separates a plurality of source and drain regions within the second semiconductor fin. Within this particular method, at least either: (1) the first gate dielectric and the second gate dielectric comprise different gate dielectric materials; or (2) the first gate electrode and the second gate electrode comprise different gate electrode materials.

Another particular method for fabricating a semiconductor structure in accordance with the invention includes forming a first semiconductor fin and a second semiconductor fin over a substrate. This other particular method also includes forming a first gate dielectric upon the first semiconductor fin and a first gate electrode upon the first gate dielectric to define the locations of a channel and a plurality of source and drain regions within the first semiconductor fin. This particular method also includes forming a second gate dielectric different than the first gate dielectric upon the second semiconductor fin and a second gate electrode different than the first gate electrode upon the second gate dielectric, to define the locations of a channel and a plurality of source and drain regions within the second semiconductor fin.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention, which includes a semiconductor structure and a method for fabricating the semiconductor structure, is understood within the context of the description set forth below. The description set forth below is understood within the context of the drawings described above. Since the drawings are intended for illustrative purposes, the drawings are not necessarily drawn to scale.

FIG. 1toFIG. 12Bshow a series of schematic cross-sectional diagrams illustrating the results of progressive stages in fabricating a semiconductor structure in accordance with a particular embodiment of the invention. This particular embodiment of the invention comprises a first embodiment of the invention.FIG. 1shows a schematic cross-sectional diagram of the semiconductor structure at an early stage in the fabrication thereof in accordance with this particular embodiment.

FIG. 1shows a base semiconductor substrate10. A buried dielectric layer12is located upon the base semiconductor substrate10, and a surface semiconductor layer14is located upon the buried dielectric layer12. In an aggregate, the base semiconductor substrate10, the buried dielectric layer12and the surface semiconductor layer14comprise a semiconductor-on-insulator substrate.

The base semiconductor substrate10may comprise any of several semiconductor materials. Non-limiting examples include silicon, germanium, silicon-germanium alloy, silicon carbide, silicon-germanium carbide alloy and compound (i.e., III-V and II-VI) semiconductor materials. Non-limiting examples of compound semiconductor materials include gallium arsenide, indium arsenide and indium phosphide semiconductor materials. Typically, the base semiconductor substrate10has a thickness from about 1 to about 3 millimeters.

The buried dielectric layer12may comprise any of several dielectric materials. Non-limiting examples include oxides, nitrides and oxynitrides, particularly of silicon, but oxides, nitrides and oxynitrides of other elements are not excluded. The buried dielectric layer12may comprise a crystalline or a non-crystalline dielectric material, with crystalline dielectric materials being highly preferred. The buried dielectric layer12may be formed using any of several methods. Non-limiting examples include ion implantation methods, thermal or plasma oxidation or nitridation methods, chemical vapor deposition methods and physical vapor deposition methods. Typically, the buried dielectric layer12comprises an oxide of the semiconductor material from which is comprised the base semiconductor substrate10. Typically, the buried dielectric layer12has a thickness from about 500 to about 2000 angstroms

The surface semiconductor layer14may comprise any of the several semiconductor materials from which the base semiconductor substrate10may be comprised. The surface semiconductor layer14and the base semiconductor substrate10may comprise either identical or different semiconductor materials with respect to chemical composition, dopant polarity, dopant concentration and crystallographic orientation. Typically, the surface semiconductor layer14may have a thickness from about 50 to about 1500 angstroms.

FIG. 1also shows: (1) a pad dielectric16located upon the surface semiconductor layer14; (2) a hard mask18located upon the pad dielectric16; and (3) a plurality of photoresist layers20located upon the hard mask18.

The pad dielectric16may comprise any of several pad dielectric materials. Silicon oxide and silicon oxynitride pad dielectric materials are common. Other pad dielectric materials, that may include, but are not necessarily limited to oxides and oxynitrides of elements other than silicon, are not excluded. Commonly, the pad dielectric16comprises a thermal silicon oxide pad dielectric material, although the embodiment and the invention also contemplate the use of other methods, such as but not limited to chemical vapor deposition methods and physical vapor deposition methods, for forming the pad dielectric16.

The hard mask18comprises a hard mask material. Silicon nitride and silicon oxynitride hard mask materials are common hard mask materials, but the use of silicon nitride and silicon oxynitride hard mask materials also by no means limits the embodiment or the invention. The hard mask18may in general be formed using methods and materials that are analogous, equivalent or identical to the methods and materials that are used for forming the pad dielectric16. Typically, the hard mask18comprises a silicon oxynitride hard mask material or a silicon oxide hard mask material that has a thickness from about 500 to about 1500 angstroms.

The photoresist layers20may comprise any of several photoresist materials. Positive photoresist materials, negative photoresist materials and hybrid (i.e., both positive acting and negative acting) photoresist materials are common. Positive and negative photoresist materials are more particularly common. Typically, the photoresist layers20comprise a positive photoresist material or a negative photoresist material that has a thickness from about 2000 to about 5000 angstroms.

FIG. 2shows a plurality of hard masks18′ located upon a plurality of pad dielectrics16′ in turn located upon a plurality of semiconductor fins14′ that are etched from the corresponding hard mask18, pad dielectric16and surface semiconductor layer14, while using the plurality of photoresist layers20as etch mask layers. The foregoing etching typically uses a plasma etch method, or a series of plasma etch methods, that uses a series of etchant gas compositions appropriate to the materials from which are comprised the hard mask18, the pad dielectric16and the surface semiconductor layer14. Generally, silicon containing dielectric materials may be efficiently etched while using a fluorine containing etchant gas composition, while silicon containing semiconductor materials may be efficiently etched using a chlorine containing etchant gas composition. The foregoing plasma etch method, or series of plasma etch methods, will typically comprise an anisotropic plasma, or a series of anisotropic plasmas, that provides nominally straight sidewalls to the hard masks18′, the pad dielectrics16′ and the semiconductor fins14′. Although not particularly illustrated withinFIG. 2, the semiconductor fin14′ stack located at the left hand side of the semiconductor structure ofFIG. 2is intended for eventual fabrication of an n-finFET that will be designated as a second transistor, while the semiconductor fin14′ stack located at the right hand side of the semiconductor structure ofFIG. 2is intended for fabrication of a p-finFET that will be designated as a first transistor.

FIG. 3first shows the results of stripping the photoresist layers20from the hard masks18′ within the semiconductor structure ofFIG. 2. The photoresist layers20may be stripped using methods and materials that are conventional in the semiconductor fabrication art. Included in particular are wet chemical photoresist stripping methods, dry plasma photoresist stripping methods and aggregates of wet chemical photoresist stripping methods and dry plasma photoresist stripping methods.

FIG. 3next shows first gate dielectrics21located upon sidewalls of the semiconductor fins14′.

The first gate dielectrics21may comprise conventional dielectric materials such as oxides, nitrides and oxynitrides of silicon that have a dielectric constant from about 4 (i.e., typically a silicon oxide) to about 8 (i.e., typically a silicon nitride), measured in vacuum. Alternatively, the first gate dielectrics21may comprise generally higher dielectric constant dielectric materials having a dielectric constant from about 8 to at least about 100. Such higher dielectric constant dielectric materials may include, but are not necessarily limited to hafnium oxides, hafnium silicates, zirconium oxides, lanthanum oxides, titanium oxides, barium-strontium-titanates (BSTs) and lead-zirconate-titanates (PZTs). The first gate dielectrics21may be formed using any of several methods that are appropriate to their material of composition. Non limiting examples include thermal or plasma oxidation or nitridation methods, chemical vapor deposition methods (including atomic layer deposition methods) and physical vapor deposition methods. Typically, the first gate dielectrics21comprise a thermal silicon oxide dielectric material that has a thickness from about 5 to about 50 angstroms. As a result of using such a thermal oxidation method, the first gate dielectrics21are formed as separated and distinct layers. Alternatively, when the first gate dielectrics21comprise a deposited dielectric material rather than a thermally grown dielectric material, the first gate dielectrics21are typically formed as a single contiguous layer.

After forming the first gate dielectrics21,FIG. 3finally shows a tri-layer stack formed and located upon the resulting semiconductor structure. The tri-layer stack includes a first gate conductor layer22located and formed upon the resulting semiconductor structure, an etch stop layer24located upon the first gate conductor layer22and a first capping layer26located upon the etch stop layer24.

Within the instant embodiment, the first gate conductor layer22may comprise any of several gate conductor materials. In particular, first gate conductor layer22may comprise materials including but not limited to certain metals, metal alloys, metal nitrides and metal silicides, as well as laminates thereof and composites thereof. The first gate conductor layer22may also comprise doped polysilicon and polysilicon-germanium alloy materials (i.e., having a dopant concentration from about 1e18 to about 1e22 dopant atoms per cubic centimeter) and polycide materials (doped polysilicon/metal silicide stack materials). Similarly, the foregoing gate conductor materials may also be formed using any of several methods. Non-limiting examples include salicide methods, chemical vapor deposition methods and physical vapor deposition methods, such as, but not limited to evaporative methods and sputtering methods. Typically, the first gate conductor layer22comprises a doped polysilicon material that has a thickness from about 200 to about 500 angstroms.

The etch stop layer24may comprise any of several etch stop materials. Conductor etch stop materials, semiconductor etch stop materials and dielectric etch stop materials are common. Dielectric etch stop materials are generally most common. Particular dielectric etch stop materials include silicon oxides, silicon nitrides and silicon oxynitrides that are formed using methods and materials analogous, equivalent or identical to the methods and materials that are used for fabricating the buried dielectric layer24. Other etch stop materials, as well as methods for fabrication thereof, are not excluded. Typically, the etch stop layer24comprises a dielectric etch stop material, such as but not limited to a thermal silicon oxide dielectric etch stop material, that has a thickness from about 30 to about 100 angstroms.

The first capping layer26may comprise any of several capping materials. Conductor capping materials, semiconductor capping materials and dielectric capping materials all comprise candidate capping materials. While by no means limiting the embodiment, the first capping layer26typically comprises a doped polysilicon conductor capping material analogous, equivalent or identical to the doped polysilicon material from which is comprised the first gate conductor layer22. Typically, the first capping layer26has a thickness from about 300 to about 500 angstroms.

FIG. 4shows a block mask28located covering the right hand side of the semiconductor structure whose schematic cross-sectional diagram is illustrated inFIG. 3.

The block mask28typically comprises a photoresist material analogous, equivalent or identical to the photoresist material from which is comprised the photoresist layers20that are illustrated inFIG. 1. However, the block mask28is formed with generally larger dimensions in comparison with the photoresist layers20. Positive photoresist materials and negative photoresist materials are again most common for forming the block mask28, but by no means limit the invention.

FIG. 5first shows the results of sequentially etching the capping layer26, the etch stop layer24and the first gate conductor layer22while using the block mask28as an etch mask, to form a corresponding capping layer26′, etch stop layer24′ and first gate conductor layer22′. Similarly with related processing steps within the instant embodiment, the foregoing etching is undertaken using a plasma etch method (i.e., typically an anisotropic plasma etch method) that is otherwise generally conventional in the semiconductor fabrication art. Again, typically, a fluorine containing etchant gas composition is used for etching a silicon containing dielectric material, while a chlorine containing etchant gas composition or a bromine containing etchant gas composition is used for etching a silicon containing semiconductor material.

FIG. 5next shows the results of stripping the block mask28from the resulting semiconductor structure. The block mask28may be stripped using methods and materials that are used for stripping the photoresist layers20from the semiconductor structure whose schematic cross-sectional diagram is illustrated inFIG. 1to provide in part the semiconductor structure whose schematic cross-sectional diagram is illustrated inFIG. 2.

FIG. 5finally shows a second tri-layer stack formed and located upon the semiconductor structure that results from etching the first gate conductor layer22, the etch stop layer24and the first capping layer26to form the corresponding first gate conductor layer22′, the etch stop layer24′ and the first capping layer26′, and then stripping from the first capping layer26the block mask28. The second tri-layer stack includes: (1) a second gate dielectric30located upon all surfaces of the post-etched and post-photoresist stripped semiconductor structure, but in particular upon sidewalls of the left hand semiconductor fin14′; (2) a second gate conductor layer32located upon the second gate dielectric30; and (3) a second capping layer34located upon the second gate conductor layer32.

The second gate dielectric30may comprise a gate dielectric material selected from the same group of gate dielectric materials as the first gate dielectrics21. However, within the instant embodiment the first gate dielectrics21and the second gate dielectric30comprise different dielectric materials selected from that group. Similarly, the second gate conductor layer32may comprise a gate conductor material selected from the same group of gate conductor materials as the first gate conductor layer22. However, and also within the context of the instant embodiment, the second gate conductor layer32also comprises a different gate conductor material in comparison with the first gate conductor layer22. Within the instant embodiment, the second gate dielectric30typically comprises a higher dielectric constant dielectric material in comparison with the first gate dielectrics21that typically comprises a thermal silicon oxide dielectric material. Within the instant embodiment, the second gate conductor layer32typically comprises a metal, metal alloy, metal nitride or metal silicide gate conductor material, such as but not limited to a titanium nitride gate conductor material, in comparison with the first gate conductor layer22′ which typically comprises a doped polysilicon gate conductor material. Typically, the second gate dielectric30has a thickness from about 5 to about 50 angstroms and the second gate conductor layer32has a thickness from about 200 to about 500 angstroms.

Finally, within the context of further disclosure below, the second capping layer34will typically comprise a conductor capping material, although the instant embodiment is not necessarily so limited, given the possibility of alternative subsequent etch schemes in comparison with the etch scheme that is described in further detail below. Typically, and for reasons that will become more apparent within the context of further disclosure below, the second capping layer34preferably comprises a doped polysilicon capping material. Preferably, the second capping layer34has a thickness from about 300 to about 500 angstroms.

FIG. 6shows a block mask28′ located upon the left hand side of the semiconductor structure whose schematic cross-sectional diagram is illustrated inFIG. 5. The block mask28′ as illustrated inFIG. 6is otherwise analogous, equivalent or identical to the block mask28that is illustrated inFIG. 4, but located upon a left hand side of the semiconductor structure whose schematic cross-sectional diagram is illustrated inFIG. 5rather than the right hand side of the semiconductor structure whose schematic cross-sectional diagram is illustrated inFIG. 5. As is illustrated within the schematic cross-sectional diagram ofFIG. 6, the block mask28′ is located in a fashion that it covers the step formed by the first gate conductor layer22′, the etch stop layer24′ and the first capping layer26′.

FIG. 7first shows the results of etching the second capping layer34, the second gate conductor layer32and the second gate dielectric30to form a corresponding second capping layer34′ (in part), a second gate conductor layer32′ and second gate dielectric30′. The foregoing etching may be effected using methods and materials that are otherwise generally conventional in the semiconductor fabrication art. Included in particular are dry plasma etch methods that use an appropriate etchant gas composition with respect to the materials from which are formed the second capping layer34, the second gate conductor layer32and the second gate dielectric30.

FIG. 7also shows the results of stripping the first capping layer26′ from the etch stop layer24′. Stripping of the first capping layer26′ from the etch stop layer24′ is typically undertaken using an isotropic etchant that provides for an undercut of the second capping layer34′ beneath the block mask28′ Such an isotropic etchant typically comprises a wet chemical etchant, such as an acidic wet chemical acidic etchant. Under certain circumstances, however, dry plasma etchants may also exhibit isotropic characteristics.

FIG. 8first shows the results of isotropically etching portions of the second gate dielectric30′ and the second gate conductor layer32′ exposed beneath the block mask28′ that is illustrated inFIG. 7to form the second gate dielectric30″ and the second gate conductor layer32″. Such isotropic etching may be effected using methods and materials that are otherwise generally conventional in the semiconductor fabrication art. Included in particular are wet chemical etch methods and dry plasma etch methods.

FIG. 8next shows the results of isotropically stripping completely the first capping layer26′ from the etch stop layer24′, and partially etching an exposed portion of the second capping layer34′ beneath the block mask28′ to form a second capping layer34″. The foregoing isotropic stripping and isotropic etching may be effected using an isotropic etchant as is similarly also conventional in the semiconductor fabrication art. Included in particular are wet chemical stripping methods and materials, and dry plasma stripping methods and materials.

FIG. 8finally shows the results of stripping the block mask28′ from the second capping layer34″ and the etch stop layer24′ from the first gate conductor layer22′ to provide the semiconductor structure that is illustrated inFIG. 8. The foregoing stripping of the block mask28′ and the etch stop layer24′ may also be effected using methods and materials that are generally conventional in the semiconductor fabrication art. Also included in particular, but also not limiting the embodiment or the invention, are wet chemical stripping methods and materials, and dry plasma stripping methods and materials.

FIG. 9shows a gate conductor capping layer36located upon the semiconductor structure ofFIG. 8. In general the gate conductor capping layer36may comprise any of the several materials disclosed above from which is comprised the first gate conductor layer22and the second gate conductor layer32. However, within the context of the instant embodiment when the first gate conductor layer22comprises a doped polysilicon conductor material and the second capping layer34″ also comprises a doped polysilicon conductor material, the gate conductor capping layer36preferably also comprises a doped polysilicon material that in effect incorporates the first gate conductor layer22′ and the second capping layer34″. Typically, the gate conductor capping layer36comprises a doped polysilicon material that has a thickness from about 300 to about 700 angstroms.

FIG. 10AandFIG. 10Bshow a schematic cross-sectional diagram and a schematic plan-view diagram illustrating the results of further processing of the semiconductor structure whose schematic cross-sectional diagram is illustrated inFIG. 9.

FIG. 10AandFIG. 10Bshow a plurality of mask layers38located upon the gate conductor capping layer36and nominally centered over each of the semiconductor fins14′.

The plurality of mask layers38may comprise photoresist materials and be formed using methods, that are otherwise analogous or equivalent to the photoresist materials and methods that are used for forming the block masks28and28′, and the photoresist layers20. However, the dimensions of the mask layers38, while in some instances similar to the photoresist layers20, may in general be smaller than the aerial dimensions of the block masks28and28′.

FIG. 11AandFIG. 11Bshow a schematic cross-sectional diagram and a schematic plan-view diagram illustrating the results of further processing of the semiconductor structure whose schematic cross-sectional diagram and schematic plan-view diagram are illustrated inFIG. 10AandFIG. 10B.

FIG. 11AandFIG. 11Bshow the results of patterning the gate conductor capping layer36and the second gate conductor layer32″ to form plurality of gate conductor capping layers36′ located one each over each of the plurality of semiconductor fins14′ and a second gate conductor layer32′″ located over the left hand semiconductor fin but not the right hand semiconductor fin14′. The foregoing etching is undertaken using methods and materials that are generally conventional in the semiconductor fabrication art. Included in particular are anisotropic dry plasma etch methods that provide generally straight sidewalls to the gate conductor capping layers36′ and the second gate conductor layer32′″.

FIG. 12AandFIG. 12Bshow a schematic cross-sectional diagram and a schematic plan-view diagram illustrating the results of further processing of the semiconductor structures whose schematic cross-sectional diagram and schematic plan-view diagram are illustrated inFIG. 11AandFIG. 11B.

FIG. 12AandFIG. 12Bshow the results of stripping the mask layers38from the semiconductor structure ofFIG. 11AandFIG. 11B, and in particular from the gate conductor capping layers36′. The mask layers38may be stripped using methods and materials that are generally conventional in the semiconductor fabrication art. Included in particular are wet chemical etch methods, dry plasma etch methods and aggregates of wet chemical etch methods and dry plasma etch methods.

As is understood by a person skilled in the art, the semiconductor structures ofFIG. 12AandFIG. 12Bmay be further processed to provide fully functional finFET devices. Such further processing may include, but is not necessarily limited to, ion implantation processing to provide source and drain regions within the semiconductor fins14′, where the source and drain regions are separated channel regions within the semiconductor fins14′ that are aligned beneath the gate conductor capping layers36′.

FIG. 12AandFIG. 12Bshow a schematic cross-sectional diagram and a schematic plan-view diagram of a semiconductor structure in accordance with an embodiment of the invention that comprises a first embodiment of the invention. The semiconductor structure includes a plurality of finFET structures and in particular a first finFET structure T1and a second finFET structure T2. Preferably, the first finFET structure T1is a p-finFET and the second finFET structure is an n-finFET to thus provide a CMOS finFET structure. Within this particular embodiment, the first finFET structure T1includes a first gate dielectric21that preferably comprises a silicon oxide dielectric material, and a first gate electrode that comprises only the gate conductor capping layer36′ that preferably comprises a doped polysilicon gate conductor material. Within this particular embodiment, the second finFET structure T2includes a second gate dielectric30″ different than the first gate dielectric21(i.e., typically comprising a higher dielectric constant dielectric material), and a second gate electrode that comprises a second gate conductor layer32′″ (i.e., that typically comprises a titanium nitride gate conductor material) upon which is located another gate conductor capping layer36′. Thus this particular embodiment provides a CMOS finFET structure where an n-finFET and a p-finFET have both a different gate dielectric material composition and a different gate electrode material composition.

As is understood by a person skilled in the art, such a differing gate electrode material composition and gate dielectric material composition may provide for enhanced performance optimization of the individual n-finFET T2and p-finFET T1within the finFET CMOS structure whose schematic cross-sectional diagram is illustrated inFIG. 12AandFIG. 12B.

FIG. 13AtoFIG. 15Bshow a series of schematic cross-sectional diagrams and schematic plan-view diagrams illustrating the results of progressive stages in fabricating a semiconductor structure in accordance with another embodiment of invention. This other embodiment of the invention comprises a second embodiment of the invention.

FIG. 13AtoFIG. 15Bcorrespond generally withFIG. 10AtoFIG. 12Bbut wherein the mask layers38that are illustrated inFIG. 10AtoFIG. 11Bhave been replaced by a single mask layer38′ that covers both of the semiconductor fins14′. As a result of using the mask layer38′ rather than the plurality of mask layers38, this second embodiment provides a single gate electrode capping layer36″ that spans between the semiconductor fins14′, as illustrated most particularly inFIG. 15AandFIG. 15B.

FIG. 15AandFIG. 15Bshow a schematic cross-sectional diagram and a schematic plan-view diagram of a semiconductor structure in accordance with a second embodiment of the invention. Similarly with the first embodiment as is illustrated inFIG. 12AandFIG. 12B, the second embodiment is also preferably comprises an n-finFET and a p-finFET to provide a CMOS finFET structure. Within the finFET CMOS structure that is illustrated inFIG. 15AandFIG. 15B, an n-finFET T2has at least one, and preferably both, a different gate dielectric composition and a different gate electrode composition, in comparison with a p-finFET T1.

As is illustrated inFIG. 15AandFIG. 15B, within the finFET CMOS structure, the n-finFET T2includes a second gate dielectric30″ that preferably comprises a higher dielectric constant dielectric material than the first gate dielectrics21that are included within the p-finFET T1. Similarly, the n-finFET T2also comprises a second gate electrode that comprises a second gate conductor layer32′″ and the contiguous gate conductor capping layer36″ while the p-finFET T1comprises a first gate that comprises only the contiguous gate conductor capping layer36″. Thus, within the second embodiment as well as the first embodiment, both the gate dielectrics and the gate electrodes of the n-finFET and the p-finFET comprise different materials.

The semiconductor structure in accordance with the second embodiment of the invention provides value in comparison with the semiconductor structure in accordance with the first embodiment insofar as the shorted gate electrodes through the contiguous gate electrode capping layer36″ may be useful in forming ring oscillators, inverters, synchronous random access memory (SRAM) and related semiconductor devices. As noted above, either of the embodiments disclosed above is desirable within the context of a CMOS structure insofar as individual n-finFET structures and p-finFET structures therein include at least one, and preferably both, of different gate dielectric materials and different gate electrode materials. The different gate dielectric materials and different gate electrode materials provide an opportunity for efficiently designing and optimizing an n-finFET with different operating parameters in comparison with a p-finFET.

The preferred embodiments of the invention are illustrative of the invention rather than limiting of the invention. Revisions and modifications may be made to methods materials, structures and dimensions of a CMOS finFET structure in accordance with the preferred embodiments, while still providing a semiconductor structure and method for fabrication thereof in accordance with the invention, further in accordance with the accompanying claims.