Abstract:
By aligning the primary flat of a wafer with a (100) plane rather than a (110) plane, devices can be formed with primary currents flowing along the (100) plane. In this case, the device will intersect the (111) plane at approximately 54.7 degrees. This intersect angle significantly reduces stress propagation/relief along the (111) direction and consequently reduces defects as well as leakage and parasitic currents. The leakage current reduction is a direct consequence of the change in the dislocation length required to short the source-drain junction. By using this technique the leakage current is reduced by up to two orders of magnitude for an N-channel CMOS device.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to the fabrication of integrated circuits and, more specifically, a method for fabricating field effect transistors (FETs) wherein source-drain current flows along a (100) crystal plane.  
       BACKGROUND  
       [0002]     Semiconductor integrated circuit chips are constructed as dice on wafers. A typical wafer material is crystalline silicon. Wafers are cut from single crystal silicon ingots grown from polysilicon by means of, for example, Czochralski method (CZ) crystal growth. CZ wafers are preferred for VLSI applications as they can withstand high thermal stresses and are able to offer an internal gettering mechanism that can remove unwanted impurities from device structures on a wafer surface. This also gives the wafer a uniform internal structure based on silicon&#39;s diamond cubic lattice structure. Although the diamond cubic lattice provides strength and rigidity to the wafer, defects in the crystal lattice, for example, slip dislocations, can adversely affect fabricated circuit electrical properties leading to a reduction in the number of good dice per wafer. A schematic representation of the diamond cubic lattice structure of silicon is depicted in  FIG. 1A .  
         [0003]     The atoms in a crystal lattice structure of a silicon wafer align with each other to form planes traversing the wafer in multiple directions. Three principal planes, and their respective orientations, (100), (110), and (111), are shown in  FIGS. 1B-1D . Equivalent planes are designated by braces, for example, {111}, {110}, and {100}, represent equivalents to the (111), (110), and (100) principal planes, respectively. In many applications, orienting the crystal to an equivalent plane will achieve the same result as aligning it to its principal plane. Many structural properties of silicon depend on its planar orientation. Plane (111) has the highest number of atoms per unit of surface area and is said to be packed very tightly. This high atomic density results in a greater number of available charge carriers, which allows for faster current propagation. Concurrently, the more tightly a crystal plane is packed, the higher the probability that slip dislocations and other defects will occur. These defects can cause parasitic currents as well as charge leaks that can lead to poor performance and device failure.  
         [0004]     To help identify crystalline planes, wafers are typically fabricated with a notch or flat relative to a selected crystalline plane. Throughout the integrated circuit (IC) manufacturing industry, automated wafer handling equipment utilize these notches or flats, fabricated in the wafers, to align the wafer, allowing devices on a wafer to be aligned with a specific crystal plane. A development in the art has been the shift to formation of semiconductor devices on a silicon wafer wherein the devices are aligned so that source-drain current in those devices travel along a {110} plane, usually the (110) plane. As indicated above, a {110} plane has a more closely packed atomic structure than a {100} plane, which coincides with a higher charge mobility in devices aligned such that current flows along the (110) plane, as compared to devices aligned such that current flows along the (100) plane. A result of this characteristic of silicon crystals is faster data throughput where device current is aligned along the (110) plane. Several U.S. patents teach the alignment of devices to a (110) plane, for example, U.S. Pat. No. 5,729,045, to Buynosik, entitled “Field Effect Transistor With Higher Mobility,” discloses a method of increasing the performance of an FET by aligning channel current with the (110) crystal plane of a (100) wafer. However, the Buynosik device is inappropriate for contemporary high-density device fabrication since any defects present in the crystal lattice can have severe deleterious effects on an electronic device. Buynosik teaches neither how to eliminate or deal with the lattice defects.  
         [0005]     In fact, an ongoing trend in microelectronics devices is a reduction in device size. Concurrently, with the scaling down of IC devices, device current paths are smaller and device currents are decreased. One result is that crystal defects and unintentional currents are proportionally larger as IC devices become smaller.  
         [0006]     One approach to reducing the problems associated with the defects discussed above is to improve the quality of the wafer itself. One method of improving the wafer is through an epitaxial deposition wherein a thin layer of single crystal silicon material is deposited on the surface of a silicon crystal substrate. These wafers are commonly known as epi wafers. Experimentation has shown that these types of wafers have higher yields than standard wafers.  
         [0007]     In  FIG. 2 , a silicon wafer  201  is shown with a single MOSFET device including a source  205 , a drain  207 , and a gate  209 , wherein a source-drain current channel is aligned to a primary flat  203 . The primary flat is typically aligned with the (110) plane and the arrow (vector) indicates a [110] direction, which is normal to the (110) plane. Most commercially available epitaxial wafers are manufactured with the primary flat aligned with the (110) plane. Traditionally, fabrication equipment aligns a wafer using a primary flat (or notch) as a reference. With a primary flat aligned with a (110) plane, devices constructed from these epitaxial wafers have current channels that are aligned along the (110) plane. With larger scale devices, this has not been a problem since any defects formed had little influence on device performance and could be ignored. However, with design rules ever decreasing, any defects present in the crystal lattice can start to have severe deleterious effects on an electronic device.  
       SUMMARY  
       [0008]     By aligning the primary flat (or notch) of, for example, an epi wafer with a (100) plane rather than a (110) plane, devices can be formed with primary currents flowing along the (100) plane. In this case, the device will intersect the (111) plane at approximately 54.7 degrees. This intersect angle significantly reduces stress propagation/relief along the (111) direction and consequently reduces defects as well as leakage and parasitic currents. Leakage current reduction is a direct consequence of the change in the dislocation length required to short the source-drain junction. By using this technique, the leakage current is reduced by up to two orders of magnitude for an n-channel CMOS device.  
         [0009]     Defects, such as slip dislocation and gettering points for impurities, are also reduced by employing the techniques presented herein.  
         [0010]     One application of an embodiment of the present invention relates to the fabrication of metal-oxide-semiconductor field effect transistors (MOSFETs). MOSFET technology is a dominant electronic device technology in use today. Performance enhancement between generations of devices is generally achieved by reducing an overall size of the device, resulting in an enhancement in device speed. This size reduction is generally referred to as device scaling. As MOSFETs are scaled to channel lengths below about 200 nm, conventional MOSFETs suffer from several problems.  
         [0011]     An improvement in MOSFET performance and yield has been observed by incorporating the present invention into the MOSFET fabrication process. By aligning the MOSFET channel so that source-drain channel current flows in the (100) plane, manufacturing related defects and related leakage and parasitic currents are reduced. Another application of various embodiments of the present invention is in the fabrication of a specific type of MOSFET device called a FinFET. A FinFET is a MOSFET with a raised current channel (fin) that utilizes a gate electrode on at least three sides of the channel. Aligning the fin with the (100) plane results in a reduction in capacitance between the gate electrode and FinFET channel and body, and superior electrical isolation between the gate electrode and FinFET channel and body. A further benefit of this fabrication method utilizing a (100) channel direction is that the corners of the gate electrode are inherently rounded, reducing local electric fields and consequently increasing the breakdown voltage and improving uniformity of an electric field in a gate dielectric. Additionally, the (100) channel direction fabrication method described herein reduces stress in silicon “corners.” This benefit is especially pronounced during high temperature processing (e.g., during growth of a thermal silicon dioxide gate dielectric). One result of the reduction in stress is that, for example, less boron p-type doping atoms diffuse out of corner regions into any adjacent existing oxide or growing oxide. There is thus less segregation of the boron into the silicon dioxide. Silicon corner regions maintain a higher doping concentration and, hence, a higher MOS threshold voltage for formation of a parasitic channel in the finished device. Reduction or elimination in the formation of the parasitic channel at low MOS gate voltages produces a substantial reduction in leakage current of the device.  
         [0012]     Concepts and techniques discussed herein may be added to various electronic devices as a mechanism by which leakage current is reduced. A skilled artisan will recognize that the present invention may be incorporated into other embodiments where parasitic device current, defects, and leakage current reduction is desired. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1A  shows a schematic of a unit cell for a diamond cubic lattice crystal as known in the prior art.  
         [0014]      FIGS. 1B-1D  show various crystal plane orientations as known in the prior art.  
         [0015]      FIG. 2  shows prior art alignment of a primary flat and device orientation on a commercially available epitaxial wafer.  
         [0016]      FIG. 3  shows the alignment of a primary flat and device orientation on a wafer with a (100) primary flat orientation.  
         [0017]      FIGS. 4A-4O  show exemplary process steps for one embodiment of the present invention.  
         [0018]      FIGS. 5A-5I  show exemplary process steps for another embodiment of the present invention.  
         [0019]      FIGS. 6A-6K  show an exemplary FinFET device fabricated using various process steps of various embodiments of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0020]     As device dimensions continue to shrink and thermal cycling continues to increase due to an increase in fabrication steps, defects (e.g., crystalline, contamination, etc.) have a more significant impact on device yield and performance. By aligning the primary flat (or notch) of, for example, an epi wafer with the (100) plane rather than the (110) plane, devices can be formed with traditional fabrication equipment wherein primary currents flow along the (100) plane rather than the (110) plane. In  FIG. 3 , an epi wafer  301 , is shown with a single MOSFET device, including a source  305 , a drain  307 , and a gate  309  wherein a source-drain current channel is aligned to a primary flat  303 . The primary flat  303  is aligned with the (100) plane. Fabricating devices with a primary current path aligned with the (100) plane reduces defects in and parallel to primary current paths and consequently reduces leakage and parasitic currents, as well as increases device yields.  
         [0021]     An exemplary embodiment utilizing the present invention is an n-channel MOSFET device with source-drain current that flows along the (100) plane. While the (100) plane is referred to throughout, a skilled artisan will recognize that many equivalent planes will result in a similar advantageous intersect angle with {110}, and {111} planes. As MOSFET fabrication technology is well known in the art, the description that follows with reference to  FIGS. 4A-4O  and  FIGS. 5A-5I  is accordingly brief.  
         [0022]     With reference to  FIG. 4A , a substrate  401  has a dielectric layer  403  formed thereon. An active layer  405 A is formed over the dielectric layer  403 . In one specific exemplary embodiment, a combination of the substrate  401 , the dielectric layer  403 , and the active layer  405 A is a silicon-on-insulator (SOI) wafer. In this embodiment, the dielectric layer  403  is a buried oxide layer having a nominal thickness of 500 nm with a practical range of thicknesses being about 15 nm to 1 μm. A thickness of the SOI active layer is nominally 2 μm with a practical range of thicknesses being about 0.3μ to 25 μm.  
         [0023]     In another specific exemplary embodiment, the substrate  401  could be virtually any material capable of withstanding process temperatures and common chemicals encountered during semiconductor fabrication processes. Such materials would include quartz reticles or glass or plastic substrates (i.e., backplanes) used for flat panel displays. In this exemplary embodiment, the dielectric layer  403  may not be required. The active layer  405 A could be a deposited polysilicon layer that is deposited and then annealed (e.g., by rapid thermal annealing (RTA) or excimer laser annealing (ELA)) to regain a monocrystalline form.  
         [0024]     In another specific exemplary embodiment, the active layer  405 A could be a thinned wafer bonded to a suitable substrate. In this embodiment, the bonded wafer is a doped p-type wafer with an epitaxial silicon layer formed thereon, although one skilled in the art will recognize that an n-type doped semiconductor wafer may be used to fabricate a p-type integrated circuit. Alternatively, a group III-V or II-VI bonded semiconductor substrate or an oxygen-implanted silicon (SIMOX) substrate may be used.  
         [0025]     Overlying the active layer  405 A is a first dielectric layer  407 A, a second dielectric layer  409 A, and a first photoresist layer  411 A. In a specific exemplary embodiment, the two dielectric layers  407 A,  409 A are a pad oxide with a 20 nm nominal thickness (having a practical range of about 16 nm to 50 nm) and a 120 nm nitride layer (having a practical range of about 100 nm to 200 nm), respectively.  
         [0026]     In  FIG. 4B , the first photoresist layer  411 A is patterned to produce an etched first photoresist layer  411 B. The etched first photoresist layer  411 B serves as a mask to etch exposed areas of the underlying active layer  405 A. If the active layer  405 A is comprised of silicon, silicon may be wet-etched, for example, with potassium hydroxide (KOH) or tetra-methyl ammonium hydroxide (TMAH). Dry-etch techniques, such as a reactive ion etch (RIE) with a fluorine rich plasma (e.g., SF 6 ) are also known in the art for etching silicon. Once etched, an etched active layer  405 B is produced having a plurality of etched trenches  413 . The plurality of trenches  413  may be, for example, approximately 500 nm in depth but a useful range may span from 150 nm to 800 nm in depth.  
         [0027]     The etched first photoresist layer  411 B is then removed ( FIG. 4C ) and a liner dielectric layer  415  is formed over exposed areas of the etched active layer  405 B (i.e., sidewalls and bottoms of the plurality of etched trenches  413 ). The liner dielectric layer  415  may be, for example, a thermal oxide grown to approximately 30 nm in thickness. The liner dielectric layer  415  may also be deposited by techniques known in the art (e.g., by chemical vapor deposition (CVD) or atomic layer deposition (ALD)).  
         [0028]     In  FIG. 4D , a second patterned and etched photoresist layer  417  serves as a mask for an ion implant  419  step. The ion implant  419  step produces a plurality of doped regions  421 . As one of skill in the art recognizes, the ion implant  419  step may readily be substituted with a dopant diffusion step.  
         [0029]     A shallow trench isolation (STI) blanket dielectric fill layer  423 A is formed (e.g., oxide formed by CVD or high density plasma (HDP) assisted deposition) so as to cover the etched second dielectric layer  409 B ( FIG. 4E ). A precise thickness of additional coverage is not critical but typically ranges from 50 nm to 300 nm over the etched second dielectric layer  409 B. The dielectric fill layer  423 A is then planarized ( FIG. 4F ) to be roughly coplanar with an uppermost portion of the etched second dielectric layer  409 B. The planarization step may be accomplished by a chemical-mechanical planarization (CMP) step using an appropriate abrasive slurry. Based on film thicknesses given various specific exemplary embodiments, supra, a planarized STI dielectric fill  423 B may be approximately 700 nm in thickness. Any remaining portion of the planarized STI dielectric fill  423 B overlying the etched second dielectric layer  409 B may be removed with a selective etchant, leaving an etched planarized STI dielectric fill  423 C ( FIG. 4G ). For example, if the planarized STI dielectric fill  423 B is comprised of oxide and the etched second dielectric layer  409 B is nitride, a chemical etchant such as hydrofluoric acid (commonly contained in a standard buffered oxide etch (BOE)), or orthophosphoric acid, or alternatively a selective dry etch technique (e.g., reactive-ion-etching (RIE)) will effectively remove the oxide while having little effect on the nitride.  
         [0030]     The etched second dielectric layer  409 B is then removed ( FIG. 4H ) followed by removal of the etched first dielectric layer  407 B ( FIG. 4I ). Assuming the etched first dielectric layer  407 B and the etched planarized STI dielectric fill  423 C are fabricated of materials having similar etch characteristics, removing the first dielectric layer  407 B also produces a secondarily-etched planarized STI dielectric fill  423 D.  
         [0031]     With reference to  FIG. 4J , a thin (e.g., approximately 20 nm) sacrificial dielectric layer  425  is either grown (e.g., if the material chosen for the sacrificial layer is silicon dioxide) or deposited on exposed areas of the etched active layer. The sacrificial dielectric layer  425  serves at least two purposes: (1) to remove contaminants, thereby cleaning exposed active regions; and (2) to act as a screening layer for subsequent dopant diffusions or implants (not shown). After the sacrificial dielectric layer  425  is formed, various device specific dopant regions may be added to the etched active layer  405 B with additional photoresist masking steps added as required. For example, a doped channel region for an MOS device could be added at this point in the process flow. Such techniques are device dependent and are known to one of skill in the art.  
         [0032]     The sacrificial dielectric layer  425  is then stripped ( FIG. 4K ). The sacrificial dielectric layer  425  may be stripped by various wet etch or dry etch techniques as described herein with reference to other similar film layers. If the sacrificial dielectric layer  425  and the STI dielectric fill  423 D are formed from a similar material (e.g., both are comprised of oxide), then stripping the sacrificial dielectric layer  425  slightly thins the STI dielectric fill  423 D as well, leaving a final STI dielectric  423 E as indicated in  FIG. 4K .  
         [0033]     In  FIG. 4L , a gate dielectric  427  is formed (e.g., by thermal oxidation or deposition) over now-cleaned and exposed areas of the etched active layer  405 B. In a specific exemplary embodiment, the gate dielectric  427  is approximately 80 Å in thickness, although gate thicknesses from 20 Å-300 Å are known in the art.  
         [0034]     A semiconductor gate layer  429 A (e.g., polysilicon) is deposited ( FIG. 4M ). In a specific exemplary embodiment, the semiconductor gate layer is approximately 350 nm thick but may range in thickness from 150 nm to 600 nm. Functionally, the semiconductor gate layer  429 A will serve various purposes, depending upon a type of device being fabricated. For example, in a Flash memory device, the semiconductor gate layer  429 A could serve as a floating gate. In an MOS transistor, the semiconductor gate layer  429 A could serve as a control gate.  
         [0035]     With reference to  FIG. 4N   1 , a third patterned and etched photoresist layer  431  is formed, allowing etching and formation of an etched gate layer  429 B. A physical width, “w,” of a final transistor fabricated from such a structure is indicated in  FIG. 4N   1 . In this arrangement, current flow in a final transistor form would be normal to the page view.  
         [0036]     A magnified area “A” is shown in more detail in  FIG. 4N   2 . Where the etched active layer  405 B has an orientation on, for example a wafer where the primary flat (or notch) is in a (100) plane (also referred to as a “C-Flat wafer, see  FIG. 3 ), upper corners (i.e., proximate to STI top corners) of the etched active layer  405 B are necessarily rounded during fabrication. This rounding produces a much more uniform electric field than the sharp corner produced by the prior art. When the electric field is more uniform, leakage current is suppressed by as much as two orders of magnitude between a MOSFET source and drain region. Consequently, leakage of charge into or through the gate dielectric  427  is diminished.  
         [0037]     In  FIG. 4O , a final gate  429 C overlays a channel region of a MOS transistor (only a single gate is shown for clarity; a skilled artisan will recognize that gates may be located over each of the active areas overlaying the gate dielectric areas  427 ). The gate  429 C is surrounded on either side by source and drain dopant regions. (Note: actual doped regions are not shown but merely indicated by areas  433  where such doped region will occur after subsequent processing. Such subsequent process steps are well-known to a skilled artisan.)  
         [0038]     In another exemplary embodiment of the present invention and with reference to  FIGS. 5A through 5I , additional and alternative fabrication techniques are depicted. Similar feature types defined in  FIGS. 5A through 5I  share similar range thicknesses as discussed with reference to  FIGS. 4A through 4O , supra. A skilled artisan will also recognize that process steps may be intermixed between fabrication steps outlined between the various sets of figures.  
         [0039]     In  FIG. 5A , a substrate  500  has a dielectric layer  501  formed thereon. In a specific exemplary embodiment, the substrate  500  is a doped p-type wafer with an epitaxial silicon layer formed thereon, although one skilled in the art will recognize that an n-type doped semiconductor wafer may be used to fabricate a p-type integrated circuit. Alternatively, any of the substrate variations described with reference to  FIG. 4A , supra, may be used. The epitaxial silicon layer is doped with a lower concentration of a dopant of the same type as the substrate  500 . A polysilicon layer  503 , is then formed by, for example, chemical vapor deposition (CVD). In a specific exemplary embodiment, the dielectric layer  501  is silicon dioxide, formed by, for example, thermal oxidation.  
         [0040]     In  FIG. 5B , a second dielectric layer  504  is formed over the polysilicon layer  503 . In a specific exemplary embodiment, the second dielectric layer  504  is silicon dioxide and is formed by, for example, CVD.  
         [0041]     With reference to  FIG. 5C , a photoresist mask  505 , with patterned apertures exposing a source region aperture  507 , and a drain region aperture  509  in the second dielectric layer  504  is formed over the polysilicon layer  503 . Both a plan view and cross section are shown.  
         [0042]     With reference to  FIG. 5D , the second dielectric layer  504  has been etched to reveal a source window  511 , and a drain window  513 ; the source window  511  and drain window  513  being aligned along a (100) plane so as to result in current flow along the (100) plane. The photoresist mask  505  has been removed. In a specific exemplary embodiment, the second dielectric layer  504  is etched using hydrofluoric acid, which attacks silicon dioxide rapidly with respect to the photoresist layer  504  and the polysilicon layer  503 . In a subsequent step, the source and drain windows  511 ,  513 , are further doped with an n-type dopant, for example, phosphorous, creating a source region  515 , and a drain region  517 . In a specific exemplary embodiment, the doping is achieved by ion-implantation, although alternative means of doping, such as diffusion, can be used. As is known to a skilled artisan, concentration levels will vary dependent on device type. The second dielectric layer  504  is used to mask the area which is doped.  
         [0043]     With reference to  FIG. 5E , a third dielectric layer  519 , is formed over the second dielectric layer  504  by, for example, physical vapor deposition (PVD). While some of the dopant will diffuse into the epitaxial semiconductor layer  503  and the third dielectric layer  519 , the concentration of dopant will remain much higher in the implanted region with respect to the epitaxial semiconductor layer  503 .  
         [0044]     With reference to  FIG. 5F , the central portion of the third dielectric layer  519  has been etched to a level coplanar with the surface of the source and drain regions  515 ,  517 . The etched area defines a gate region (discussed below).  
         [0045]     With reference to  FIG. 5G , a gate dielectric  520 , is formed over the gate region. In an exemplary embodiment, a thin oxide layer is formed by, for example, thermal oxidization. In a subsequent step, contact holes  521 ,  523 , are formed using a photoresist to define the area to be etched, then etching the oxide layer  519  by, for example, hydrofluoric acid.  FIG. 5G  includes a top view as well.  
         [0046]     With reference to  FIG. 5H , a metallization layer  525 , is conformally formed by, for example, ion beam deposition. In a specific embodiment, the metallization layer  525  is aluminum.  
         [0047]     With reference to  FIG. 5I , a photoresist layer (not shown) is applied to the metallization layer  525  and is patterned to result in electrical separation of a source contact  527 , a drain contact  529 , and a gate contact  531 . The metallization layer is etched by, for example, ion beam milling. A top view is included.  
         [0048]     By fabricating the device with the source and drain aligned with the (100) plane so that source-drain channel current flows along the (100) plane, fabrication induced crystal defects and resultant leakage and parasitic device currents can be reduced.  
         [0049]     Another exemplary embodiment utilizing the present invention is a FinFET device with source-drain current that flows along a (100) plane. In a specific embodiment, a silicon substrate with a commercially available epitaxial silicon layer grown on the surface is used. While the (100) plane is referred to throughout, a skilled artisan will recognize many equivalent planes that will result in an advantageous intersect angle with {110}, and {111} planes.  
         [0050]     With reference to  FIG. 6A , a silicon portion  601 A of a silicon-on-insulator (SOI) substrate has a thin silicon dioxide layer  603 A, a thicker silicon nitride layer  605 A, and a patterned photoresist mask layer  607 . In a specific exemplary embodiment, the substrate is a silicon-on-insulator wafer. However, a skilled artisan will recognize that other semiconductor materials may be used instead of an SOI wafer for the substrate. Other semiconductor materials include, for example, elemental semiconductors such as germanium, compound semiconductors such as group III-V, and II-VI materials, and semiconducting alloys (e.g., Al x Ga 1-x As, HG 1-x CD x Te). If elemental semiconductors other than silicon, or compound semiconductors are employed, an atomic layer deposition (ALD) process may be employed for producing thin, high quality oxide layers.  
         [0051]     The silicon dioxide layer  603 A is a pad oxide to prevent thermally-induced stresses from developing between particular dissimilar materials, such as between silicon and the silicon nitride layer  605 A. The silicon dioxide layer  603 A may be thermally grown or deposited. The silicon nitride layer  605 A is then formed over the silicon dioxide layer  603 A by, for example, chemical vapor deposition (CVD). In a specific exemplary embodiment, the silicon dioxide layer  605 A is between 50 Å and 200 Å while the silicon nitride layer  605 A is between 400 Å and 2000 Å. The patterned photoresist mask layer  607  may be repeated a number of times and disposed laterally over a surface of the substrate  601 A to fabricate multiple surrounded-gate devices. For clarity, only one such device will be shown and described herein.  
         [0052]      FIG. 6B  indicates a fin area  602  being fabricated from the silicon portion of an SOI wafer, exposing an insulating portion  601 B. To form the fin area  602 , the photoresist mask layer  607  defines an area for which underlying areas will not be etched. These layers (i.e., the silicon nitride layer  605 A and silicon dioxide layer  603 A) are etched in accordance with methods well-known in the semiconductor arts. For example, depending upon a chemical composition of a given layer, etching may be accomplished through various wet etch (e.g., in hydrofluoric acid, such as contained in a standard buffered oxide etch, or orthophosphoric acid) or dry-etch techniques (e.g., reactive-ion etch (RIE)). Once an etched silicon nitride layer  605 B and an etched silicon dioxide layer  603 B are formed, the underlying substrate  601 A is etched, defining the etched substrate  601 B. If the substrate  601 A is comprised of silicon, silicon may be wet-etched, for example, with potassium hydroxide (KOH) or tetra-methyl ammonium hydroxide (TMAH). Dry-etch techniques, such as a reactive ion etch (RIE) with a fluorine rich plasma (e.g., SF 6 ) are also known in the art for etching silicon. The fin is aligned along the (100) plane so that source-drain current will flow along the (100) plane.  
         [0053]     A sidewall slope of the fin area  602  may be controlled through a choice of the chemistry used in a dry-etch recipe and/or through a choice of the substrate  601 A if a monocrystalline semiconductor is used. If a silicon wafer is chosen for the substrate  601 A, a dry-etch process may be chosen to etch approximately 90° sidewalls on the fin area  602 . Therefore, the fin area  602  can be fabricated in such a way so as to maximize a given surface area to volume ratio of the fin  602  thereby allowing electrical characteristics (e.g., carrier mobility) of the FET device to be modified and tuned.  
         [0054]     After producing the fin area  602 , the photoresist mask layer  607  is removed ( FIG. 6C ) and a gate oxide layer  609  is thermally grown ( FIG. 6D ) after an appropriate pre-oxidation clean. In other exemplary embodiments, the gate oxide layer may be conformally deposited by CVD. Thinner layers of gate oxide (e.g., 20 Å to 30 Å) may be deposited by techniques such as atomic layer deposition (ALD).  
         [0055]     In  FIG. 6E , a dielectric fill layer  611 A is deposited over the gate oxide layer  609 . The dielectric fill process may be similar to shallow-trench isolation (STI) type fills known in the art, for example, a high density plasma (HDP) oxide fill. The dielectric fill layer  611 A may be comprised of any insulative material such as silicon dioxide, sapphire, borophosphosilicate glass (BPSG), or any of a number of other materials deposited or otherwise formed over the gate oxide layer  609 . The dielectric fill layer  611 A may also be comprised of oxynitride or a high-k dielectric material. However, if oxynitride is used for the dielectric fill layer  611 A, then an additional masking step will be used to prevent the etched oxynitride layer  605 B from being etched away in subsequent process steps. The dielectric fill layer  611 A may be brought to a level roughly coplanar with an uppermost part of the etched silicon nitride layer  605 B through, for example, chemical mechanical planarization (CMP).  
         [0056]     The dielectric fill layer  611 A is then etched, producing an etched dielectric fill layer  611 B ( FIG. 6F ). A high-selectivity etchant prevents the etched silicon nitride layer  605 B from being substantially etched away during the dielectric fill layer  611 A etch. Further, if the gate oxide layer  609  is comprised of thermally grown silicon dioxide, the gate oxide layer  609  will etch more slowly than an HDP layer used for the dielectric fill layer  611 A (i.e., an etch rate of thermal oxide is lower than HDP oxide as HDP is less dense). If an exposed portion of the gate oxide layer  609  (i.e., the portion above the etched dielectric fill layer  611 B) is not etched completely, it will be removed prior to a final gate oxidation step described infra.  
         [0057]     With reference to  FIG. 6G , the etched silicon nitride layer  605 B, the etched silicon dioxide layer  603 B, and exposed portions of the gate oxide layer  609  are substantially etched away using techniques known to a skilled artisan. An exposed section of the fin area  602  defines an active region of the FET device. The active region has a given height, H, length, L 1 , and width, W. In a specific exemplary embodiment, the active region height, H, is approximately 100 nm to 450 nm. The width of the active region, W, is approximately 100 nm or less and the length, L 1 , is dependent on a number of factors such as device design rules and gate widths.  
         [0058]     A thermal oxidation, ALD, or high-k oxide deposition process forms a final thin gate oxide  613 A ( FIG. 6H ) over the active region. In a specific exemplary embodiment, the final thin gate oxide is grown or deposited to a thickness of approximately 20 Å to 30 Å. A polysilicon layer  615 A is then conformally deposited ( FIG. 6H ). The polysilicon layer  615 A will form a gate region, described infra. A patterned second photoresist layer  617  is formed and patterned to define the gate; the gate having a width commensurate with a length, L 2 , of the patterned second photoresist layer  617 .  FIG. 6I  is a plan view of the FET device and thus provides clarity in understanding a layout of the device after the second photoresist layer  617  is added. The hidden section is an uppermost portion of the channel active region of  FIG. 6G .  
         [0059]     With reference to  FIG. 6J , a selective etch process (either wet-etch or dry-etch) is used to fully define a gate region  615 B of the device. Generally, a high selectivity to either silicon or silicon dioxide is accomplished using CHF 3 /O 2 , CH 2 F 2 , or CH 3 F chemistry. Doped areas are added (e.g., by diffusion or implantation) to define a drain contact region  619  and a source contact region  621  of the device. The patterned second photoresist layer  617  is then removed.  FIG. 6K  provides a plan view—showing source, gate, and drain contact areas—of a completed FinFET device fabricated according to exemplary embodiments descried herein.  
         [0060]     In the foregoing specification, the present invention has been described with reference to specific embodiments thereof. It will, however, be evident to a skilled artisan that various modifications and changes can be made thereto without departing from the broader spirit and scope of the invention as set forth in the appended claims. For example, skilled artisans will appreciate that other types of semiconducting (e.g., any crystalline semiconducting material) and insulating materials other than those listed may be employed. Additional particular process fabrication and deposition techniques, such as low pressure chemical vapor deposition (LPCVD), ultra-high vacuum CVD (UHCVD), and low pressure tetra-ethoxysilane (LPTEOS) may be readily employed for various layers and still be within the scope of the present invention. Although the exemplary embodiments are described in terms of MOS integrated circuit devices, a person of ordinary skill in the art will recognize that other fabrication techniques, such as bipolar or BiCMOS techniques, may readily be employed as well.  
         [0061]     While fabrication methods aligning primary device current with the (100) plane is referred to with respect to the exemplary embodiments included herein, a skilled artisan will recognize the use of many equivalent planes that will result in an advantageous intersect angle with {110}, and {111} planes without departing from the scope of the present invention. Additionally, concepts and techniques discussed herein may be added to various electronic devices as a mechanism by which leakage current is reduced. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.