Abstract:
A method of manufacturing multiple finFET devices having different thickness gate oxides. The method may include depositing a first dielectric layer on top of the semiconductor substrate, on top of a first fin, and on top of a second fin; forming a first dummy gate stack; forming a second dummy gate stack; removing the first and second dummy gates selective to the first and second gate oxides; masking a portion of the semiconductor structure comprising the second fin, and removing the first gate oxide from atop the first fin; and depositing a second dielectric layer within the first opening, and within the second opening, the second dielectric layer being located on top of the first fin and adjacent to the exposed sidewalls of the first pair of dielectric spacers, and on top of the second gate oxide and adjacent to the exposed sidewalls of the second pair of dielectric spacers.

Description:
FIELD OF THE INVENTION 
       [0001]    The present disclosure generally relates to integrated circuits, and more particularly to fabricating semiconductor devices having different thickness gate oxides on the same semiconductor substrate. 
       BACKGROUND OF INVENTION 
       [0002]    An increasing demand exists for providing semiconductor devices having gate oxide layers of varying thicknesses, for example field effect transistors (FET). In fact, the gate oxide thickness is a major concern in terms of reliability when providing integrated circuit devices containing transistors and other circuit elements that operate at differing voltage levels. By way of example, a relatively thin gate oxide may typically range from 8 Å to 20 Å in thickness, while a relatively thick gate oxide may typically range from 12 Å to 60 Å in thickness. 
         [0003]    Device scaling trends have led to low voltage operation with relatively thin gate oxide; whereas, some circuit applications still require a relatively thick gate oxide, such as driver or receiver circuitry at the chip I/O, and some analog output devices. The thick gate oxide is necessary for high voltage devices in order to ensure reliability, while the thin gate oxide is desirable for the relatively fast logic devices that use low voltages at the gate. Use of relatively thick gate oxide for the lower voltage transistors cause poor device performance and significantly decrease the speed, therefore the need for multiple thickness gate oxides. 
         [0004]    Moreover, with the trend of trying to put as many different circuits as possible in the same chip to achieve more functionality and improved performance (such as Merged logic-DRAM, embedded NVM micro-controls), there are even more different possible combinations for different parts of circuits in the same chip to have different gate oxide thickness to achieve the optimized performance and reliability at the system level. 
         [0005]    Referring to  FIG. 22 , typical fabrication of a semiconductor device, such as a planar FET, includes oxidizing a surface of a substrate  202  to form a dielectric layer. The oxidized dielectric layer may be referred to as a grown dielectric layer. Next, a layer of polysilicon may be deposited on top of the grown dielectric layer. The grown dielectric layer and the polysilicon layer are patterned and etched to form dummy gate stacks. Each dummy gate stack has a gate oxide made from the grown dielectric layer. The gate oxides may a common thickness. Also, each gate stack includes a dummy gate (not shown) made from the polysilicon layer. 
         [0006]    After etching the gate stacks spacers  210   a ,  210   b ,  216   a ,  216   b  may be formed on opposite sides of each dummy gate stack as shown in the figure. Next, an inter layer dielectric (ILD) material  204  may be disposed between the devices to electrically insulate one device from another. The ILD  204  may be polished preferably using a chemical and mechanical polishing (CMP) process to expose the tops of the dummy gates stacks. The exposed polysilicon dummy gates (note shown) may then be removed using an etching process and are typically replaced with a metal gate terminal  208 ,  214 . The dummy gates may be replaced with a metal or any other semiconducting material known to a person of ordinary skill in the art. Alternatively, the entire dummy gate stack including the polysilicon dummy gate and the gate oxide may be removed with an etching technique and replaced with a high-k dielectric and metal gate terminal. This technique may be referred to as replacement gate (RG) or gate-last processing. 
         [0007]    During the RG processing there exists a potential for the thickness of the gate oxide to be compromised by the etching process during the removal of the polysilicon dummy gate in preparation for depositing a gate terminal  208 ,  214 . The thickness of the gate oxide may be harmed by either the etchants used to remove the polysilicon dummy gates or a post etching process, typically RIE, used to clean and remove polymers attacking the underlying gate oxide  206 . 
         [0008]    Further, to fabricate different gate oxide thicknesses (e.g.  206  and  212 ) on the same semiconductor substrate an additional iteration of the process described above (oxidize-mask-etch) is required for each additional thickness desired. However, such an approach typically significantly increases the overall manufacturing cost and degrades the reliability as well as yield due to the potential contamination caused by resist residues from the patterning required. Besides, controlling the gate oxide thickness is more difficult because the thick oxide layer results from the combination of multiple oxide formation cycles, and it may be damaged by the etching process described above. This introduces multiple sources of variability due to the multiple steps required to fabricate the thick gate oxide layers. Additionally, the oxidize-mask-etch process described above may cause ILD loss because the ILD remains unprotected during processing. An unprotected ILD can have recesses that fill with Al or other metals during replacement gate processing. Excess metal collected in these recesses can lead to a short circuit. 
         [0009]    A similar RG technique may be used to fabricate finFET devices. Fabrication of finFET devices using RG techniques includes patterning and etching fins into a semiconductor substrate. The semiconductor substrate may include any bulk substrate or SOI substrate know to a person of ordinary skill in the art. A first gate dielectric may be grown on the fins by oxidizing the surface of the semiconductor substrate. The process of growing the first gate dielectric includes oxidizing the surface of the semiconductor substrate. This process consumes some of the semiconductor material in effect reducing the width of the fins. Next, a polysilicon layer may be deposited on top of the gate dielectric layer from which dummy gates may be pattered and etched. After etching, a portion of the gate dielectric may remain beneath the dummy gates, and the dummy gate and gate dielectric form dummy gate stacks. A pair of spacers may be disposed on opposite sidewalls of each dummy gate stacks. The dummy gates may then be removed to create openings. Some openings may be masked while others may remain open. A second gate dielectric may be grown on top of the first gate dielectric in the unmasked openings. Next, the mask may be removed and metal gate terminals may be formed in the openings between the spacers and on top of the first gate dielectric and the second gate dielectric. 
       SUMMARY 
       [0010]    According to one embodiment of the present disclosure, a method of manufacturing a semiconductor structure including multiple finFET devices each including different thickness gate oxides and formed in a semiconductor substrate is provided. The method may include depositing a first dielectric layer on top of the semiconductor substrate, on top of a first fin, and on top of a second fin, forming a first dummy gate stack including a first dummy gate located on top of a first gate oxide above the first fin, and a first pair of dielectric spacers disposed on opposite sides of the first dummy gate stack, and forming a second dummy gate stack including a second dummy gate located on top of a second gate oxide above the second fin, and a second pair of dielectric spacers disposed on opposite sides of the second dummy gate stack. The method may also include removing the first dummy gate and the second dummy gate selective to the first and second gate oxides, and creating a first opening defined by exposed sidewalls of the first pair of dielectric spacers and a second opening defined by exposed sidewalls of the second pair of dielectric spacers, masking a portion of the semiconductor structure including the second fin, and removing the first gate oxide from atop the first fin, and depositing a second dielectric layer within the first opening, and within the second opening, the second dielectric layer being located on top of the first fin and adjacent to the exposed sidewalls of the first pair of dielectric spacers, the second dielectric layer being located on top of the second gate oxide and adjacent to the exposed sidewalls of the second pair of dielectric spacers. 
         [0011]    According another exemplary embodiment, a semiconductor structure including multiple finFET devices each including different thickness gate oxides and formed in a semiconductor substrate is provided. The structure may include a semiconductor substrate including a first fin and a second fin, a first gate stack including a first terminal located above the first fin, and a first pair of dielectric spacers disposed on opposite sides of the first gate stack, the first gate stack including a dielectric layer located between the first fin and the gate terminal and between the gate terminal and the pair of spacers, and a second gate stack including a gate oxide and a second terminal located above the second fin, and a second pair of dielectric spacers disposed on opposite sides of the second gate stack, the gate oxide being located on top of the second fin and the gate terminal being located on top of the gate oxide, the second gate stack including the dielectric layer located between the gate oxide and the gate terminal and between the gate terminal and the pair of spacers. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0012]    The following detailed description, given by way of example and not intend to limit the disclosure solely thereto, will best be appreciated in conjunction with the accompanying drawings, in which: 
           [0013]      FIGS. 1-21  illustrate the steps of a method of fabricating a semiconductor structure according to one embodiment. 
           [0014]      FIG. 1  depicts an isometric view of a first and a second fin formed in a semiconductor substrate according to one embodiment. 
           [0015]      FIG. 2  depicts the deposition of a first dielectric layer according to one embodiment. 
           [0016]      FIG. 3  depicts the deposition of a sacrificial layer according to one embodiment. 
           [0017]      FIG. 4  depicts the formation of dummy gates according to one embodiment. 
           [0018]      FIG. 5  depicts the formation of spacers on opposite sides of the dummy gates according to one embodiment. 
           [0019]      FIG. 6  depicts the deposition of an inter-layer dielectric formed on top of the semiconductor substrate and surrounding the dummy gates according to one embodiment. 
           [0020]      FIG. 7  depicts the removal of the dummy gates according to one embodiment. 
           [0021]      FIG. 8  depicts cross-sectional view A-A of  FIG. 7 , in which the dummy gates are removed. 
           [0022]      FIG. 9  depicts cross-sectional view B-B of  FIG. 7 , in which the dummy gates are removed. 
           [0023]      FIG. 10  depicts the deposition of a resist mask on top of the first dielectric layer above the second fin and the subsequent removal of the first dielectric layer from atop the first fin according to one embodiment. 
           [0024]      FIG. 11  depicts cross-sectional view C-C of  FIG. 10 , in which the first dielectric layer is removed from atop the first fin. 
           [0025]      FIG. 12  depicts cross-sectional view D-D of  FIG. 10 , in which the first dielectric layer is removed from atop the first fin. 
           [0026]      FIG. 13  depicts cross-sectional view E-E of  FIG. 10 , in which the first dielectric layer is removed from atop the first fin. 
           [0027]      FIG. 14  depicts the deposition of a second dielectric layer on top of the first fin and on top of the first dielectric layer above the second fin according to one embodiment. 
           [0028]      FIG. 15  depicts cross-sectional view F-F of  FIG. 14 , in which the second dielectric layer is deposited on top of the first fin and on top of the first dielectric layer above the second fin. 
           [0029]      FIG. 16  depicts cross-sectional view F-F of  FIG. 14 , in which the second dielectric layer is deposited on top of the first fin and on top of the first dielectric layer above the second fin. 
           [0030]      FIG. 17  depicts cross-sectional view F-F of  FIG. 14 , in which the second dielectric layer is deposited on top of the first fin and on top of the first dielectric layer above the second fin. 
           [0031]      FIG. 18  depicts the deposition of gate terminals on top of the second dielectric layer according to one embodiment. 
           [0032]      FIG. 19  depicts cross-sectional view I-I of  FIG. 18 , in which gate terminals are formed on top of the second dielectric layer. 
           [0033]      FIG. 20  depicts cross-sectional view I-I of  FIG. 18 , in which gate terminals are formed on top of the second dielectric layer. 
           [0034]      FIG. 21  depicts cross-sectional view I-I of  FIG. 18 , in which gate terminals are formed on top of the second dielectric layer. 
           [0035]      FIG. 22  is a cross-sectional side view diagram of a conventional semiconductor structure with two planar FET devices each having different thickness gate oxides. 
       
    
    
     DETAILED DESCRIPTION 
       [0036]    Detailed embodiments of the claimed structures and methods are disclosed herein; however, it can be understood that the disclosed embodiments are merely illustrative of the claimed structures and methods that may be embodied in various forms. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiment set forth herein. Rather, these exemplary embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of this disclosure to those skilled in the art. In the description, details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the presented embodiments. 
         [0037]    The drawings are not necessarily to scale. The drawings are merely schematic representations, not intended to portray specific parameters of the invention. The drawings are intended to depict only typical embodiments of the invention. In the drawings, like numbering represents like elements. 
         [0038]    A finFET device includes a plurality of fins formed in a wafer; a gate covering a portion of the fins, wherein the portion of the fins covered by the gate serves as a channel region of the device and portions of the fins extending out from under the gate serve as source and drain regions of the device; and spacers on opposite sides of the gate. 
         [0039]    In a RG fabrication approach, a semiconductor substrate may be patterned and etched to form fins. Next, a dummy gate may be formed in a direction perpendicular to the length of the fins. For example, the dummy gate may be pattered and etched from a polysilicon layer. A pair of spacers can be disposed on opposite sidewalls of the dummy gate. Later, the dummy gate may be removed from between the pair of spacers, as by, for example, an anisotropic vertical etch process such as a reactive ion etch (RIE). This creates an opening between the spacers where a metal gate may then be formed between the spacers. A gate dielectric may be configured below the metal gate. Devices may include gate dielectrics with different thicknesses. Formation of multiple finFET devices having different thickness gate dielectrics using RG fabrication techniques is described in greater detail below. 
         [0040]    Referring now to  FIGS. 1-15 , exemplary process steps of forming FETs, such as finFETs, having different thickness gate oxides on a single semiconductor integrated circuit in accordance with one embodiment of the present invention are shown. In particular, a high performance finFET device may have a thin gate oxide, and an I/O finFET device may have a thick gate oxide. Standard replacement gate (RG) processing techniques, as described above, may be used to form both high performance finFET devices and I/O finFET devices. The particular process point in which the gate oxide layers are formed during standard RG processing may vary. These variations are described in detail below as different embodiments. 
         [0041]    Referring now to  FIG. 1 , a first fin  102  and a second fin  104  are shown formed in an SOI substrate. It should be noted that the fins  102  and  104  may be formed in any semiconductor substrate know to a person having ordinary skill in the art. The first fin  102  depicts the beginning stages of the fabrication of a single high performance device while the second fin  104  depicts the beginning stages of the fabrication of a single I/O device. It should be noted that a single integrated circuit may include multiple high performance devices and multiple I/O devices. Conventional photolithography techniques known to a person having ordinary skill in the art may be used to form the fins  102 ,  104  in the SOI substrate. 
         [0042]    With continued reference to  FIG. 1 , a silicon-on-insulator (SOI) substrate  140  is shown. The SOI substrate  140  may include a buried oxide (BOX) layer  142  and a silicon-on-insulator (SOI) layer  144  formed on top of the BOX layer  142 . In one embodiment, the SOI substrate  140  may have an oxide layer  146  and a nitride layer  148  formed on a top surface of the SOI layer  144 , where the nitride layer  148  may be located directly on top of the oxide layer  146 . 
         [0043]    The BOX layer  142  may be formed from any of several dielectric materials. Non-limiting examples include, for example, oxides, nitrides and oxynitrides of silicon. The BOX layer  142  may also include oxides, nitrides and oxynitrides of elements other than silicon. In addition, the BOX layer  142  may include crystalline or non-crystalline dielectric material. Moreover, the BOX layer  142  may 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. The BOX layer  142  may include a thickness ranging from about 5 nm to about 200 nm. In one embodiment, the BOX layer  142  may be about 25 nm thick. 
         [0044]    The SOI layer  144  may be made from any of several known semiconductor materials such as, for example, a bulk silicon substrate. Other non-limiting examples include silicon, germanium, silicon-germanium alloy, silicon carbide, silicon-germanium carbide alloy, and compound (e.g. III-V and II-VI) semiconductor materials. Non-limiting examples of compound semiconductor materials include gallium arsenide, indium arsenide, and indium phosphide. Typically, the SOI layer  144  includes a thickness ranging from about 5 nm to about 100 nm. Methods for making the SOI layer  144  are well known in the art. Non-limiting examples include SIMOX (Separation by Implantation of OXygen), wafer bonding, and ELTRAN® (Epitaxial Layer TRANsfer). 
         [0045]    The oxide layer  146  may include a silicon oxide or a silicon oxynitride. In one embodiment, the oxide layer  146  can be formed, for example, by thermal or plasma conversion of a top surface of the SOI layer  144  into a dielectric material such as silicon oxide or silicon oxynitride. In one embodiment, the oxide layer  146  can be formed by deposition of silicon oxide or silicon oxynitride by chemical vapor deposition (CVD) or atomic layer deposition (ALD). The oxide layer  146  may have a thickness ranging from about 1 nm to about 10 nm, although a thickness less than 1 nm and greater than 10 nm may be acceptable. In one embodiment, the oxide layer  146  may be about 5 nm thick. 
         [0046]    The nitride layer  148  may include an insulating material such as, for example, silicon nitride. The nitride layer  148  may be formed using conventional deposition methods, for example, low-pressure chemical vapor deposition (LPCVD). In one embodiment, the nitride layer  148  may have a thickness ranging from about 5 nm to about 100 nm. In one particular embodiment, the nitride layer  148  may be about 50 nm thick. 
         [0047]    Referring now to  FIG. 2 , a first dielectric layer  106  may be deposited conformal to the surface of the SOI substrate  140 , the first fin  102 , and the second fin  104 . In one embodiment, the first dielectric layer  106  may include, but is not limited to, a material made from hafnium silicate (HfSiO x ), hafnium oxide (HfO 2 ), zirconium silicate (ZrSiO x ), zirconium oxide (ZrO 2 ), silicon nitride (Si 3 N 4 ), silicon oxynitride (SiON), or other high-k material (greater than 4.0) or any combination of these materials. In one embodiment, the first dielectric layer  106  may include silicon oxide (SiO 2 ) deposited using an atomic layer deposition (ALD) technique. The first dielectric layer  106  may have a thickness ranging from about 12 Å to 60 Å, although a thickness of the first dielectric layer  106  less than 12 Å or greater than 60 Å is acceptable. 
         [0048]    Now referring to  FIG. 3 , a sacrificial layer  107  is formed on top of the first dielectric layer  106 . The sacrificial layer  107  may be used to form dummy gates to be used in conjunction with standard replacement gate processing. The sacrificial layer  107  may be deposited using any suitable technique such as atomic layer deposition (ALD), chemical vapor deposition (CVD), or physical vapor deposition (PVD). In one embodiment, the sacrificial layer  107  may be made from polysilicon. A chemical mechanical polishing (CMP) technique may be used to smooth a top surface of the sacrificial layer  107 . 
         [0049]    With continued reference to  FIG. 3 , a first resist mask  108  may be applied to the top surface of the sacrificial layer  107 . Conventional photolithography techniques known to a person having ordinary skill in the art may be used to pattern dummy gates (shown in  FIG. 4 ) from the sacrificial layer  107  using the first resist mask  108 . Portions of the sacrificial layer  107  and the first dielectric layer  106  not covered by the first resist mask  108  may be removed selective to the BOX layer  142 , the first fin  102 , and the second fin  104 . In one embodiment, for example, reactive ion etching (RIE) may be used to remove the sacrificial layer  107  and the first dielectric layer  106  not covered by the resist mask. 
         [0050]    Now referring to  FIG. 4 , a first gate stack  109  and a second gate stack  111  patterned from the sacrificial layer  107 ,  FIG. 3 , and the first dielectric layer  106  are shown. The first resist mask  108 ,  FIG. 3 , may be removed after patterning of the first and second gate stacks  109  and  111 . The first gate stack  109  may include a first dummy gate  110  and a portion of the first dielectric layer  106 . The second gate stack  111  may include a second dummy gate  112  and a portion of the first dielectric layer  106 . 
         [0051]    Now referring to  FIG. 5 , a first pair of dielectric spacers  114   a ,  114   b  may be formed on opposite sides of the first dummy gate  110  and a second pair of dielectric spacers  116   a ,  116   b  may be formed on opposite sides of the second dummy gate  112 . Conventional photolithography techniques known to a person having ordinary skill in the art may be used to form the first pair of dielectric spacers  114   a ,  114   b  and the second pair of dielectric spacers  116   a ,  116   b.    
         [0052]    Now referring to  FIG. 6 , an interlayer dielectric (ILD) material  118 , deposited on top of the SOI substrate  140 , the first fin  102 , the second fin  104 , the first pair of spacers  114   a ,  114   b , and the second pair of spacers  116   a ,  116   b , is shown. A CMP technique may be used to smooth a top surface of the ILD material  118 , the first dummy gate  110 , and the second dummy gate  112 . 
         [0053]    Now referring to  FIG. 7 , the first dummy gate  110 ,  FIG. 6 , and the second dummy gate  112 ,  FIG. 6 , may be removed selective to the first dielectric layer  106 . In one embodiment, isotropic wet etching may be used to remove the first dummy gate  110 ,  FIG. 6 , and the second dummy gate  112 ,  FIG. 6 . In one embodiment, the isotropic wet etching technique may use one of the following compounds, tetra methyl ammonium hydroxide (TMAH), warm or hot ammonia, or hot tetra eethyl ammonium hydroxide (TEMH). In on embodiment, the isotropic wet etching technique may use ammonium hydroxide. In one embodiment, for example, reactive ion etching (RIE) may be used to remove the first dummy gate  110 ,  FIG. 6 , and the second dummy gate  112 ,  FIG. 6 . Removal of the first dummy gate  110 ,  FIG. 6 , and the second dummy gate  112 ,  FIG. 6 , creates a first opening  120  and a second opening  122 , as shown in the figure. 
         [0054]      FIGS. 8 and 9  each depict a cross-sectional view of  FIG. 7 . Cross section A-A is depicted in  FIG. 8 . Cross section B-B is depicted in  FIG. 9 . Referring to both  FIGS. 8 and 9 , the first dielectric layer  106  is shown conformal to the BOX layer  142 , the first fin  102 , and the second fin  104 , but only in the openings  120 ,  122 ,  FIG. 7 , created by the removal of the first dummy gate  110 ,  FIG. 6 , and the second dummy gate  112 ,  FIG. 6 . Therefore, the first dielectric layer  106  may be deposited conformal to the fins  102 ,  104  of both the high performance finFET device and the I/O finFET device, as shown in the figure. 
         [0055]    Referring now to  FIG. 10 , a second resist mask  124  is shown in place of the second dummy gate  112 ,  FIG. 6 , in the second opening  122 ,  FIG. 7 . After the second dummy gate  112 ,  FIG. 6 , is removed the second resist mask  124  may be applied directly on top of the first dielectric layer  106 , but only within the second opening  122 ,  FIG. 7 . The second resist mask  124  may be not applied on top of the first dielectric layer  106  within the first opening  120 . Therefore, the second resist mask  124  may be applied directly on top of the first dielectric later  106  of the I/O finFET device and not on top of the first dielectric layer  106  of the high performance finFET device. The first dielectric layer  106  may then be removed from all areas not protected by the second resist mask  124 . More specifically, an etching technique may be used to remove the first dielectric layer  106  from within the first opening  120  selective to the BOX layer  142  and the fin  102 . In one embodiment, isotropic wet etching may be used to remove the first dielectric layer  106 . In one embodiment, the isotropic wet etching technique may use one of the following compounds, tetra methyl ammonium hydroxide (TMAH), warm or hot ammonia, or hot tetra eethyl ammonium hydroxide (TEMH). In one embodiment, the isotropic wet etching technique may use ammonium hydroxide. In one embodiment, for example, reactive ion etching (RIE) may be used to remove the first dielectric layer  106  from within the first opening  120 . Therefore, the removal technique described above removes the first dielectric layer  106  only from within the first opening  120  and not from within the second opening  122 ,  FIG. 7 . Therefore, the first dielectric layer  106  remains within the second opening  122 ,  FIG. 7  and on top of the second fin  104  of the I/O device after the removal process described above. 
         [0056]    Removal of the first dielectric layer  106  from within the first opening  120  exposes the BOX layer  142  and first fin  102  within that opening. The surface of the BOX  142  layer and the first fin  102  remain undamaged throughout the removal process because the etching technique may be limited to remove on the deposited thickness of the first dielectric layer  106 . This is possible because the first dielectric layer  106  may be deposited conformal to the surface geometry of the BOX layer  142  and the first fin  102  and have a constant thickness. 
         [0057]      FIGS. 11 ,  12 , and  13  each depict a cross-sectional view of  FIG. 10 . Cross section C-C is depicted in  FIG. 11 . Cross section D-D is depicted in  FIG. 12 . Cross section E-E is depicted in  FIG. 13 . Referring to  FIGS. 11 ,  12  and  13 , the first dielectric layer  106  is shown conformal to the BOX layer  142  and the second fin  104  within the second opening  122 ,  FIG. 7 . The first dielectric layer  106  is no longer shown conformal to the BOX layer  142  and the first fin  102  within the first opening  120 . Therefore the first dielectric layer  106  remains deposited conformal to the second fin  104  of the I/O finFET device and no longer exists on top of the first fin  102  of the high performance device. 
         [0058]    Referring now to  FIG. 14 , a second dielectric layer  126  may be deposited conformal to the surface of the SOI substrate  140  and the first fin  102  within the first opening  120 , and conformal to the first dielectric layer  106  within the second opening  122 . In one embodiment, the second dielectric layer  126  may include, but is not limited to, a material made from hafnium silicate (HfSiO x ), hafnium oxide (HfO 2 ), zirconium silicate (ZrSiO x ), zirconium oxide (ZrO 2 ), silicon nitride (Si 3 N 4 ), silicon oxynitride (SiON), or other high-k material (greater than 4.0) or any combination of these materials. In one embodiment, the second dielectric layer  126  may include silicon oxide (SiO 2 ) deposited using an atomic layer deposition (ALD) technique. The second dielectric layer  126  may have a thickness ranging from about 8 Å to 20 Å, although a thickness of the second dielectric layer  126  less than 8 Å or greater than 20 Å is acceptable. 
         [0059]      FIGS. 15 ,  16 , and  17  each depict a cross-sectional view of  FIG. 14 . Cross section F-F is depicted in  FIG. 15 . Cross section G-G is depicted in  FIG. 16 . Cross section H-H is depicted in  FIG. 17 . Referring to  FIGS. 15 ,  16  and  17 , the second dielectric layer  126  is shown conformal to the SOI substrate  140  and the first fin  102  within the first opening  120 , and conformal to the first dielectric layer  106  within the second opening  122 . Therefore, the second dielectric layer  126  may serve as the gate oxide for the high performance device and both the first dielectric layer  106  and the second dielectric layer  126  may serve as the gate oxide for the I/O device. 
         [0060]    Referring now to  FIG. 18 , a first gate terminal  128  and a second gate terminal  130  may be deposited. The formation of the gate terminals  128 ,  130  may include any now known or later developed replacement gate techniques. The first gate terminal  128  and the second gate terminal  130  may include any work function metal, seal metal, or low resistance bulk metal fill appropriate for the finFET device to be created. For example, materials such as aluminum, titanium nitride (TiN) ruthenium (Ru), titanium aluminum (TiAl), tantalum nitride (TaN), or tantalum carbide (TaC) may be used. Although shown as a single metal deposition, it is understood that multiple metal depositions using appropriate masking techniques may be employed to provide the appropriate metal over the correct areas. In one embodiment, a high-k layer may be deposited on top of the gate oxides before depositing the gate terminals. Finally, a CMP process may be used to remove excess metal deposited on the top surface of the ILD  118  during the formation of the first gate terminal  128  and the second gate terminal  130 . 
         [0061]      FIGS. 19 ,  20 , and  21  each depict a cross-sectional view of  FIG. 18 . Cross section I-I is depicted in  FIG. 19 . Cross section J-J is depicted in  FIG. 20 . Cross section K-K is depicted in  FIG. 21 . Referring to  FIGS. 19 ,  20  and  21 , the first gate terminal  128  is shown on top of the second dielectric layer  126  above the first fin  102 , and the second gate terminal  130  is shown on top of the second dielectric layer  126  above the first dielectric layer  106  and the second fin  104 . Therefore, the first gate terminal  128  may serve as the gate terminal for the high performance device and the second gate terminal  130  may serve as the gate terminal for the I/O device. 
         [0062]    Without reference to a particular drawing or set of drawings one variation of the above process is described below. In one embodiment, the sacrificial layer  107  may be deposited on top of the first and second fins  102 ,  104  followed by a CMP technique to smooth the top surface of the sacrificial layer  107 . Next, the first dummy gate  110  and the second dummy gate  112  may be formed from the sacrificial layer  107  using conventional photolithography techniques. The spacers  114   a ,  114   b ,  116   a ,  116   b  may then be formed on opposite sides of the dummy gates  110 ,  112 . Next, the ILD material  118  may be deposited on top of the SOI substrate, the first fin  102 , the second fin  104 , the first pair of spacers  114   a ,  114   b , and the second pair of spacers  116   a ,  116   b . A CMP technique may be used to smooth the top surface of the ILD material  118 , the first dummy gate  110 , and the second dummy gate  112 . The dummy gates  110 ,  112  may then be removed selective to the second dielectric layer  126  crating the openings  120 ,  122 . 
         [0063]    Next, a resist mask (not shown) may be applied above the first fin  102  and the first dielectric layer  106  may be deposited conformal to the surface of the SOI substrate and the second fin  104 , but only within the opening  122 . The resist mark may then be removed and another resist mask (not shown) may be deposited directly on top of the first dielectric  106  layer formed over the second fin  104 . Next, the second dielectric layer  126  may be deposited conformal to the surface of the SOI substrate and the first fin  102 , but only within the opening  120 . After the another resist mask is removed, gate terminals  128 ,  130  may then be formed within the openings  120 ,  122 , and on top of the first dielectric layer  106  and the second dielectric layer  126 . 
         [0064]    Without reference to a particular drawing or set of drawings one variation of the above process is described below. In one embodiment, the first dielectric layer  106  may be deposited conformal to the surface of the SOI substrate, the first fin  102 , and the second fin  104 . Next, a second resist mask  124  may be deposited directly on top of the first dielectric  106  layer formed over the second fin  104 . The second resist mask  124  may not be deposited on top of the first dielectric layer  106  formed over the first fin  102 . The first dielectric layer  106  may then be removed from atop the first fin  102 . Next, the second dielectric layer  126  may be deposited on top of the first fin  102  and on top of the first dielectric layer  106 . The sacrificial layer  107  may then be deposited on top of the second dielectric layer  126  followed by a CMP technique to smooth the top surface of the sacrificial layer  107 . 
         [0065]    Next, the first dummy gate  110  and the second dummy gate  112  may be formed from the sacrificial layer  107  using conventional photolithography techniques. The spacers  114   a ,  114   b ,  116   a ,  116   b  may then be formed on opposite sides of the dummy gates  110 ,  112 . Next, the ILD material  118  may be deposited on top of the SOI substrate, the first fin  102 , the second fin  104 , the first pair of spacers  114   a ,  114   b , and the second pair of spacers  116   a ,  116   b . A CMP technique may be used to smooth the top surface of the ILD material  118 , the first dummy gate  110 , and the second dummy gate  112 . The dummy gates  110 ,  112  may then be removed selective to the second dielectric layer  126  crating the openings  120 ,  122 . Next, gate terminals  128 ,  130  may be formed within the openings  120 ,  122 . 
         [0066]    Without reference to a particular drawing or set of drawings one variation of the above process is described below. In one embodiment, a thin barrier layer can be deposited on to the surface of the SOI substrate, the first fin  102 , and the second fin  104 . The thin barrier layer may be made from a material that will allow for easy removal of the sacrificial layer without causing damage to the underlying substrate. In one embodiment, the thin barrier layer may be made from an oxide or a nitride. Next, the sacrificial layer  107  may be deposited on top of the thin barrier layer followed by a CMP technique to smooth the top surface of the sacrificial layer  107 . Next, the first dummy gate  110  and the second dummy gate  112  may be formed from the sacrificial layer  107  using conventional photolithography techniques. The spacers  114   a ,  114   b ,  116   a ,  116   b  may then be formed on opposite sides of the dummy gates  110 ,  112 . Next, the ILD material  118  may be deposited on top of the SOI substrate, the first fin  102 , the second fin  104 , the first pair of spacers  114   a ,  114   b , and the second pair of spacers  116   a ,  116   b . A CMP technique may be used to smooth the top surface of the ILD material  118 , the first dummy gate  110 , and the second dummy gate  112 . The dummy gates  110 ,  112  may then be removed selective to the thin barrier layer crating the openings  120 ,  122 . 
         [0067]    Next, the first dielectric layer  106  may be deposited conformal to the surface of the SOI substrate, the first fin  102 , and the second fin  104 , but only within the openings  120 ,  122 . A second resist mask  124  may be deposited directly on top of the first dielectric  106  layer formed over the second fin  104 . The resist mask  124  may not be deposited on top of the first dielectric layer  106  formed over the first fin  102 . Next, the first dielectric layer  106  may be removed from atop the first fin  102 . Next, the second dielectric layer  126  may be deposited on top of the first fin  102  and on top of the first dielectric layer  106 . Gate terminals  128 ,  130  may then be formed within the openings  120 ,  122 . 
         [0068]    The descriptions of the various embodiments of the present disclosure have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the embodiment, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.