Patent Publication Number: US-11664268-B2

Title: Dummy fin structures and methods of forming same

Description:
PRIORITY CLAIM AND CROSS-REFERENCE 
     This patent application is a continuation of U.S. application Ser. No. 16/713,981, filed Dec. 13, 2019, which is a continuation of U.S. application Ser. No. 16/103,988, filed on Aug. 16, 2018, now U.S. Pat. No. 10,510,580, issued Dec. 17, 2019, which claims priority to U.S. Provisional Application No. 62/566,045, filed on Sep. 29, 2017 and entitled “Dummy Fin Structures and Methods of Forming Same,” which application is hereby incorporated by reference herein as if reproduced in its entirety. 
    
    
     BACKGROUND 
     Semiconductor devices are used in a variety of electronic applications, such as, for example, personal computers, cell phones, digital cameras, and other electronic equipment. Semiconductor devices are typically fabricated by sequentially depositing insulating or dielectric layers, conductive layers, and semiconductor layers of material over a semiconductor substrate, and patterning the various material layers using lithography to form circuit components and elements thereon. 
     The semiconductor industry continues to improve the integration density of various electronic components (e.g., transistors, diodes, resistors, capacitors, etc.) by continual reductions in minimum feature size, which allow more components to be integrated into a given area. However, as the minimum features sizes are reduced, additional problems arise that should be addressed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. 
         FIG.  1    illustrates an example of a FinFET in a three-dimensional view, in accordance with some embodiments. 
         FIGS.  2 ,  3 ,  4 ,  5 ,  6 ,  7 A,  7 B,  8 ,  9 ,  10 A,  10 B,  10 C,  11 A,  11 B,  11 C,  11 D,  12 A,  12 B,  12 C,  13 A,  13 B ,  13 C,  14 A,  14 B,  14 C,  14 D,  15 A,  15 B,  15 C,  16 A,  16 B,  16 C,  17 A,  17 B, and  17 C illustrate varying views of intermediary stages of manufacturing a device in accordance with some embodiments. 
         FIGS.  17 D,  17 E, and  17 F  illustrate varying views of a device in accordance with some alternative embodiments. 
         FIGS.  18  through  22    illustrate cross-sectional views of intermediary stages of manufacturing a device in accordance with some alternative embodiments. 
         FIGS.  23  through  27 ,  28 A,  28 B, and  28 C  illustrate cross-sectional views of intermediary stages of manufacturing a device in accordance with some alternative embodiments. 
         FIGS.  28 D,  28 E, and  28 F  illustrate varying views of a device in accordance with some alternative embodiments. 
         FIGS.  29 ,  30 A,  30 B, and  30 C  illustrate cross-sectional views of intermediary stages of manufacturing a device in accordance with some alternative embodiments. 
         FIGS.  31 ,  32 A,  32 B, and  32 C  illustrate cross-sectional views of intermediary stages of manufacturing a device in accordance with some alternative embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. 
     Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly. 
     Various embodiments provide structures and processes for forming dummy fins on a semiconductor substrate having fin field effect transistors (finFET). During the fabrication process of embodiment finFET devices, dummy gate stacks may be initially formed over and along sidewalls of semiconductor fins. These dummy gate stacks are used as placeholders to define the position of subsequently formed functional gate stacks during various manufacturing processes (e.g., the formation of source/drain regions and the like). This process may also be referred to as a replacement gate process. 
     As a result of downsizing semiconductor features, fine-pitched dummy gate stacks may be formed in advanced technology nodes. During formation of fine-pitched dummy gate stacks, it may be desirable to maintain a uniform pattern of dummy gate stacks even in areas where no semiconductor fins are formed. For example, dummy gate stacks may be disposed directly on isolation regions disposed around the semiconductor fins in areas with uneven fin spacing and/or between boundaries of different finFET regions. However due to the fin-pitch and high aspect ratio of dummy gate stacks that are not formed over and along sidewalls of fins, these “unanchored” dummy gate stacks may be prone to collapse during the manufacturing process. For example, anchored dummy gate stacks are formed over and along sidewalls of semiconductor fins and are structurally supported by the semiconductor fins on which they are disposed. In contrast, unanchored dummy gate stacks are only formed over an insolation region (e.g., and not along sidewalls of the insolation region) and are less physically secure compared to anchored gate stacks. Various embodiments aim to reduce manufacturing defects by forming dummy fins (e.g., comprising one or more insulating layers) in order to anchor dummy gate stacks not formed on semiconductor fins. It has been observed that anchoring dummy gate stacks in this manner results in fewer manufacturing defects. Another benefit of dummy fins is the ability to use the dummy fins to reduce source/drain bridging during source/drain epitaxial growth processes as described in greater detail below. 
       FIG.  1    illustrates an example of a FinFET in a three-dimensional view, in accordance with some embodiments. The FinFET comprises a fin  52  on a substrate  50  (e.g., a semiconductor substrate). Isolation regions  64  are disposed in the substrate  50 , and the fin  52  protrudes above and from between neighboring isolation regions  64 . Although the isolation regions  64  are described/illustrated as being separate from the substrate  50 , as used herein the term “substrate” may be used to refer to just the semiconductor substrate or a semiconductor substrate inclusive of isolation regions. A gate dielectric layer  92  is along sidewalls and over a top surface of the fin  52 , and a gate electrode  94  is over the gate dielectric layer  92 . Source/drain regions  82  are disposed in opposite sides of the fin  52  with respect to the gate dielectric layer  92  and gate electrode  94 .  FIG.  1    further illustrates reference cross-sections that are used in later figures. Cross-section A-A is along a longitudinal axis of the gate electrode  94  and in a direction, for example perpendicular to the direction of current flow between the source/drain regions  82  of the FinFET. Cross-section B-B is parallel to cross-section A-A and extends through a source/drain region of the FinFET. Cross-section C-C is perpendicular to cross-section A-A and is along a longitudinal axis of the fin  52  and in a direction of, for example, a current flow between the source/drain regions  82  of the FinFET. Subsequent figures refer to these reference cross-sections for clarity. 
       FIGS.  2  through  17 C  are varying views of intermediate stages in the manufacturing of FinFETs, in accordance with some embodiments.  FIGS.  2  through  8 ,  18  through  27 ,  29 , and  30    illustrate reference cross-section A-A illustrated in  FIG.  1   , except for multiple fins/FinFETs.  FIG.  9    illustrates a top-down view. In  FIGS.  10 A through  17 C and  28 A through  28 C , figures ending with an “A” designation are illustrated along reference cross-section A-A illustrated in  FIG.  1   ; figures ending with a “B” designation are illustrated along a similar cross-section B-B illustrated in  FIG.  1   ; and figures ending with “C” designation are illustrated along a similar cross-section C-C illustrated in  FIG.  1   , except for multiple fins/FinFETs. Further,  FIGS.  17 D and  28 D  are illustrated along reference cross-section A-A illustrated in  FIG.  1   ;  FIGS.  17 E,  14 D, and  28 E  are illustrated along reference cross-section B-B in  FIG.  1   ; and  FIGS.  17 F and  27 F  are illustrated along reference cross-section C-C in  FIG.  1   . 
     In  FIG.  2   , a substrate  50  is provided. The substrate  50  may be a semiconductor substrate, such as a bulk semiconductor, a semiconductor-on-insulator (SOI) substrate, or the like, which may be doped (e.g., with a p-type or an n-type dopant) or undoped. The substrate  50  may be a wafer, such as a silicon wafer. Generally, an SOI substrate is a layer of a semiconductor material formed on an insulator layer. The insulator layer may be, for example, a buried oxide (BOX) layer, a silicon oxide layer, or the like. The insulator layer is provided on a substrate, typically a silicon or glass substrate. Other substrates, such as a multi-layered or gradient substrate may also be used. In some embodiments, the semiconductor material of the substrate  50  may include silicon; germanium; a compound semiconductor including silicon carbide, gallium arsenic, gallium phosphide, indium phosphide, indium arsenide, and/or indium antimonide; an alloy semiconductor including SiGe, GaAsP, AlInAs, AlGaAs, GaInAs, GaInP, and/or GaInAsP; or combinations thereof. 
     The substrate  50  has a region  50 C and a region  50 D. The region  50 C can be for forming n-type devices, such as NMOS transistors, e.g., n-type FinFETs. The region  50 D can be for forming p-type devices, such as PMOS transistors, e.g., p-type FinFETs. The region  50 C may be physically separated from the region  50 D (as illustrated by divider  51 ), and any number of device features (e.g., other active devices, doped regions, isolation structures, etc.) may be disposed between the region  50 C and the region  50 D. In some embodiments, both the region  50 C and the region  50 D are used to form the same type of devices, such as both regions being for n-type devices or p-type devices. In subsequent description, only one region (e.g., either region  50 C or  50 D) is illustrated and any differences in forming different features in the other regions are described. 
     In  FIG.  3   , fins  52  are formed in the substrate  50 . The fins  52  are semiconductor strips. In some embodiments, the fins  52  may be formed in the substrate  50  by etching trenches in the substrate  50 . The etching may be any acceptable etch process, such as a reactive ion etch (RIE), neutral beam etch (NBE), the like, or a combination thereof. The etch may be anisotropic. In such embodiment, a mask layer  54  may be used to define a pattern of the fins  52 . In some embodiments, the mask layer  54  may comprise silicon oxide, silicon nitride, silicon oxynitride, or the like. In some embodiments, the mask layer  54  comprises multiple sub-layers, such as a sub-layer of silicon nitride over a sub-layer of silicon oxide. 
     The fins may be patterned by any suitable method. For example, the fins may be patterned using one or more photolithography processes, including double-patterning or multi-patterning processes. Generally, double-patterning or multi-patterning processes combine photolithography and self-aligned processes, allowing patterns to be created that have, for example, pitches smaller than what is otherwise obtainable using a single, direct photolithography process. For example, in one embodiment, a sacrificial layer is formed over a substrate and patterned using a photolithography process. Spacers are formed alongside the patterned sacrificial layer using a self-aligned process. The sacrificial layer is then removed, and the remaining spacers may then be used to pattern the fins. 
     In  FIG.  4   , a dielectric liner  56  is deposited over and along sidewalls of the fins  52 . The dielectric liner  56  may further extend along top surfaces of the fins  52  and top surfaces of the substrate  50  between the fins  52 . The deposition of the dielectric liner  56  may be performed using a conformal deposition process, such as, chemical vapor deposition (CVD), atomic layer deposition (ALD), or the like. The dielectric liner  56  may comprise any suitable insulating material, such as, silicon oxide, or the like. 
     In  FIG.  5   , an optional dielectric liner  58  is deposited over the dielectric liner  56  such that the dielectric liner  58  is disposed along sidewalls and top surfaces of the fins  52 . The dielectric liner  58  may further extend along top surfaces of the substrate  50  between the fins  52 . The deposition of the dielectric liner  58  may be performed using a conformal deposition process, such as, CVD, ALD, or the like. The dielectric liner  58  may comprise a carbon-containing dielectric film (e.g., a carbon-containing oxide, such as, SiOC), a metal-containing dielectric film (e.g., a metal-containing oxide, such as, a combination of SiO and a metal), combinations thereof, or the like. In other embodiments, the dielectric liner  58  may be omitted (see e.g.,  FIGS.  17 C- 17 E ). 
     In  FIG.  6   , a dielectric material  60  is deposited over the dielectric films  56  and  58 . The dielectric material  60  may be deposited between the fins  52  to fill or overfill areas between the fins  52 . In some embodiments, the dielectric material  60  may be deposited using a flowable deposition process, a spin-on process, or the like. In some embodiments, the deposition of the dielectric material  60  may define voids  61  between adjacent ones of the fins  52  and between the dielectric material  60  and the dielectric films  56 / 58 . The voids  61  may be formed, for example, due to a high aspect ratio between adjacent ones of the fins  52 . A height of voids  61  may be less than a final height of subsequently formed dummy fins (e.g., tops of voids  61  may be lower than tops of dummy fins  62 , see  FIG.  8   ). It has been observed that by observing this height relationship, device performance is not negatively affected by the presence of the voids  61 . In other embodiments, the voids  61  are not formed. The dielectric material  60  may comprise a carbon-containing dielectric film (e.g., a carbon-containing oxide, such as, SiOC), a metal-containing dielectric film (e.g., a metal-containing oxide, such as, a combination of SiO and a metal), or the like. In some embodiments, a carbon and/or metal percentage by weight of the dielectric material  60  is less than a corresponding carbon/metal percentage by weight of the dielectric liner  58  (if present). For example, the dielectric liner  58  may comprise SiOC with more than 10% by weight of carbon, and the dielectric material  60  may comprise SiOC with less than 10% by weight of carbon. 
     In  FIG.  7 A , a planarization (e.g., a chemical mechanical polish (CMP)) and/or etch back process (e.g., a dry etching process) is used to expose upper surfaces of the fins  52 . In particular, upper portions of the dielectric material  60 , the dielectric liner  58  (if present), the dielectric liner  56 , and the mask layer  54  are removed so that fins  52  are exposed. In some embodiments, exposing the fins  52  results in upper surfaces of the dielectric material  60 , the dielectric liner  58 , the dielectric liner  56 , and the fins  52  being substantially coplanar. In other embodiments, exposing the fins  52  results in upper surfaces of the dielectric material  60 , the dielectric liner  58 , the dielectric liner  56 , and the fins  52  being non-coplanar (see e.g.,  FIG.  7 B ). Variances in height may be due to the different material compositions of the fins  52 , the dielectric liner  56 , the dielectric liner  58  (if present), and the dielectric material  60  being polished/etched at different rates during an applicable planarization process. Although subsequent figures illustrate these upper surfaces as being coplanar for ease of illustration, it is understood that embodiments with non-coplanar upper surfaces, such as illustrated by  FIG.  7 B , are also contemplated in subsequent processing steps and/or subsequently described embodiments. 
     In  FIG.  8   , an additional etch back process is performed on the dielectric liner  56 . The dielectric liner  56  is recessed such that portions of semiconductor fins  52  and dummy fins  62  protrude above top surfaces of the dielectric liner  56 . In some embodiments, after recessing, a height of the semiconductor fins  52  may be substantially the same as a height of the dummy fins  62 . Dummy fins  62  are made of upper portions of the dielectric liner  58  (if present) and upper portions of the dielectric material  60 , which extend above a top surface of the dielectric liner  56 . Thus, the dummy fins  62  may have a different material composition than semiconductor fins  52 , and the dummy fins  62  may be insulating fins. Further, remaining portions of the dielectric liner  56 , lower portions of the dielectric liner  58 , and lower portions of the dielectric material  60  (referred to collectively as isolation region  64 ) provide electrical isolation between adjacent fins  52  and may further provide shallow trench isolation (STI) regions between the fins  52  such that a separate STI region need not be formed. 
     In other embodiments, a separate STI region is formed (e.g., between a bottom surface of the dielectric film  56  and the substrate  50 ). For example,  FIG.  29    illustrates an embodiment where a separate STI region  204  is formed between bottom surfaces of the dielectric film  56  and top surfaces of the substrate  50  (labeled as  50 A). STI region  204  may comprise a suitable insulating material, such as, silicon oxide, silicon nitride, silicon oxynitride, combinations thereof, or the like. In the embodiment of  FIG.  29   , individual fins  52  may be connected by a mesa  50 A (sometimes referred to as a crown). Mesa  50 A is a portion of the substrate  50 . Multiple fins  52  may extend from a single mesa  50 A, which is connected to a lower portion of the substrate  50  (labeled as  50 B). Mesa  50 A may provide improved structural stability in the formation of high aspect ratio fins (e.g., fins  52 ). STI region  204  may be formed to extend along lower portions of the fins  52  as well as along sidewalls of the mesa  50 A. Mesa  50 A may be patterned and STI region  204  may be formed prior to the deposition of the dielectric film  56  in various embodiments. Although subsequent figures illustrate embodiments where the mesa  50 A and STI region  204  are excluded, this is for ease of illustration only. It should be recognized that the embodiment of  FIG.  29    may be incorporated into subsequent process steps and combined with subsequent descriptions. For example,  FIGS.  30 A,  30 B, and  30 C  illustrate a finFET device after further processing, e.g., using similar processes as described below in  FIGS.  10 A through  17 C  where like reference numerals indicate like elements formed using like processes, incorporating a separate STI region as described with respect to  FIG.  29   .  FIG.  30 A  is taken along reference cross-section A-A of  FIG.  1   ;  FIG.  30 B  is taken along reference cross-section B-B of  FIG.  1   ; and  FIG.  30 C  is taken along reference cross-section C-C of  FIG.  1   . 
     Referring back to  FIG.  8   , patterning dielectric liner  56  may use a selective etching process which selectively etches the dielectric liner  56  at a faster rate than the dielectric liner  58 , the dielectric material  60 , and the fins  52 . For example, the etching process may use fluorine and nitrogen containing chemistries, or the like, and the etching may be performed at a temperature of about 30° C. to about 120° C. Such selective etching may be enabled, for example, by the inclusion of carbon and/or a metal in the dielectric liner  58  and the dielectric material  60 . 
     In some embodiments, it may be advantageous to epitaxially grow a material in an NMOS region different from the material in a PMOS region. In various embodiments, the fins  52  may be formed from silicon germanium (Si x Ge 1-x , where x can be in the range of 0 to 1), silicon carbide, pure or substantially pure germanium, a III-V compound semiconductor, a II-VI compound semiconductor, or the like. For example, the available materials for forming III-V compound semiconductor include, but are not limited to, InAs, AlAs, GaAs, InP, GaN, InGaAs, InAlAs, GaSb, AlSb, AlP, GaP, and the like. 
     Further in  FIG.  8   , appropriate wells (not shown) may be formed in the fins the fins  52  and/or the substrate  50 . In some embodiments, a P well may be formed in the region  50 C, and an N well may be formed in the region  50 D. In some embodiments, a P well or an N well are formed in both the region  50 C and the region  50 D. 
     In the embodiments with different well types, the different implant steps for the region  50 C and the region  50 D (see  FIG.  2   ) may be achieved using a photoresist or other masks (not shown). For example, a photoresist may be formed over the fins  52  and the dummy fins  62  in the region  50 C. The photoresist is patterned to expose the region  50 D of the substrate  50 , such as a PMOS region. The photoresist can be formed by using a spin-on technique and can be patterned using acceptable photolithography techniques. Once the photoresist is patterned, an n-type impurity implant is performed in the region  50 D, and the photoresist may act as a mask to substantially prevent n-type impurities from being implanted into the region  50 C, such as an NMOS region. The n-type impurities may be phosphorus, arsenic, or the like implanted in the region to a concentration of equal to or less than 10 18  cm −3 , such as between about 10 17  cm −3  and about 10 18  cm −3 . After the implant, the photoresist is removed, such as by an acceptable ashing process. 
     Following the implanting of the region  50 D, a photoresist is formed over the fins  52  and the dummy fins  62  in the region  50 D. The photoresist is patterned to expose the region  50 C of the substrate  50 , such as the NMOS region. The photoresist can be formed by using a spin-on technique and can be patterned using acceptable photolithography techniques. Once the photoresist is patterned, a p-type impurity implant may be performed in the region  50 C, and the photoresist may act as a mask to substantially prevent p-type impurities from being implanted into the region  50 D, such as the PMOS region. The p-type impurities may be boron, BF 2 , or the like implanted in the region to a concentration of equal to or less than 10 18  cm −3 , such as between about 10 17  cm −3  and about 10 18  cm −3 . After the implant, the photoresist may be removed, such as by an acceptable ashing process. 
     After the implants of the region  50 C and the region  50 D, an anneal may be performed to activate the p-type and/or n-type impurities that were implanted. In some embodiments, the grown materials of epitaxial fins may be in situ doped during growth, which may obviate the implantations, although in situ and implantation doping may be used together. 
       FIG.  9    illustrates a top-down view of the fins  52  and the dummy fins  62 . As illustrated, the fins  52  are surrounded by insulating materials (e.g., a combination of the dielectric film  56 , the dielectric film  58 , and the dielectric material  60 ). Further, in the dummy fins  62 , the dielectric material  60  may be surrounded by the dielectric film  58 .  FIG.  9    illustrates various cross-sections, which are referenced in subsequent figures. Cross-section D-D corresponds to cross-section A-A of  FIG.  1   ; cross-section E-E corresponds to cross-section B-B of  FIG.  1   , and cross-section F-F corresponds to cross-section C-C of  FIG.  1   . 
     In  FIGS.  10 A,  10 B, and  10 C , a dummy dielectric layer  66  is formed on the fins  52  and the dummy fins  62 .  FIG.  10 A  illustrates a cross-sectional view taken along line D-D of  FIG.  9    and line A-A of  FIG.  1   ;  FIG.  10 B  illustrates a cross-sectional view taken along line E-E of  FIG.  9    and line B-B of  FIG.  1   ; and  FIG.  10 C  illustrates a cross-sectional view taken along line F-F of  FIG.  9    and line C-C of  FIG.  1   . The dummy dielectric layer  66  may be, for example, silicon oxide, silicon nitride, a combination thereof, or the like, and may be deposited or thermally grown according to acceptable techniques. For example,  FIGS.  10 A through  10 C  illustrate the dummy dielectric layer  66  formed using an embodiment thermal oxidation process where the dummy dielectric layer  66  is be selectively grown on the semiconductor fins  52  without being grown on the dummy fins  62 . In other embodiments (e.g., where dummy dielectric layer  66  is deposited), the dummy dielectric layer  66  is formed on the semiconductor fins  52  as well as the dummy fins  62 . A dummy gate layer  68  is formed over the dummy dielectric layer  66 , and a mask layer  70  is formed over the dummy gate layer  68 . The dummy gate layer  68  may be deposited over the dummy dielectric layer  68  and then planarized, such as by a CMP. The mask layer  70  may be deposited over the dummy gate layer  68 . The dummy gate layer  68  may be a conductive material and may be selected from a group including polycrystalline-silicon (polysilicon), polycrystalline silicon-germanium (poly-SiGe), metallic nitrides, metallic silicides, metallic oxides, and metals. In one embodiment, amorphous silicon is deposited and recrystallized to create polysilicon. The dummy gate layer  68  may be deposited by physical vapor deposition (PVD), CVD, sputter deposition, or other techniques known and used in the art for depositing conductive materials. The dummy gate layer  68  may be made of other materials that have a high etching selectivity from the etching of isolation regions. The mask layer  70  may include, for example, SiN, SiON, or the like. In this example, a single dummy gate layer  68  and a single mask layer  70  are formed across the region  50 C and the region  50 D (see  FIG.  2   ). In some embodiments, separate dummy gate layers may be formed in the region  50 C and the region  50 D, and separate mask layers may be formed in the region  50 C and the region  50 D. 
       FIGS.  11 A through  17 C  illustrate various additional steps in the manufacturing of embodiment devices.  FIGS.  11 A through  16 C  illustrate features in either of the region  50 C and the region  50 D. For example, the structures illustrated in  FIGS.  11 A through  16 C  may be applicable to both the region  50 C and the region  50 D. Differences (if any) in the structures of the region  50 C and the region  50 D are described in the text accompanying each figure. 
     In  FIGS.  11 A,  11 B,  11 C, and  11 D , the mask layer  70  may be patterned using acceptable photolithography and etching techniques to form masks  70 .  FIG.  11 D  illustrates a top down view of the semiconductor device.  FIG.  11    illustrates various cross-sections, which are referenced in subsequent figures. Cross-section D-D corresponds to cross-section A-A of  FIG.  1   ; cross-section E-E corresponds to cross-section B-B of  FIG.  1   , and cross-section F-F corresponds to cross-section C-C of  FIG.  1   .  FIG.  11 A  illustrates a cross-sectional view taken along line A-A of  FIG.  1    and line D-D of  FIG.  11 D ;  FIG.  11 B  illustrates a cross-sectional view taken along line B-B of  FIG.  1    and line E-E of  FIG.  11 D ; and  FIG.  11 C  illustrates a cross-sectional view taken along line C-C of  FIG.  1    and line F-F of  FIG.  11 D . 
     The pattern of the masks  70  then may be transferred to the dummy gate layer  78  and the dummy dielectric layer  66  by an acceptable etching technique to form dummy gates  72 . The dummy gates  72  cover respective channel regions of the fins  52 . The pattern of the masks  70  may be used to physically separate each of the dummy gates  72  from adjacent dummy gates. The dummy gates  72  may also have a lengthwise direction substantially perpendicular to the lengthwise direction of respective epitaxial fins  52  and the dummy fins  62 . Further the dummy fins  62  may provide additional structural support for the dummy gates  72  formed over and along sidewalls of the dummy fins  62 . For example, absent the dummy fins  62 , the dummy gates  72  not disposed over the fins  52  may be formed with planar bottom surfaces. In such embodiments (e.g., absent the dummy fins  62 ), the dummy gates  72  with planar bottom surfaces has less structural support and may collapse especially when the dummy gates  72  have high aspect ratios (e.g., with heights in a range of about 130 nm to about 160 nm and widths in the range of about 10 nm to about 20 nm), resulting in manufacturing defects, Thus, the inclusion of the dummy fins  62  in various embodiments may advantageously improve the structural support for the dummy gates  72  and reduce manufacturing defects. 
     Further, gate seal spacers (not explicitly illustrated) can be formed on exposed surfaces of the dummy gates  72 , the masks  70 , and/or the fins  52 . A thermal oxidation or a deposition followed by an anisotropic etch may form the gate seal spacers. 
     After the formation of the gate seal spacers, implants for lightly doped source/drain (LDD) regions (not explicitly illustrated) may be performed. In the embodiments with different device types, similar to the implants discussed above in  FIG.  8   , a mask, such as a photoresist, may be formed over the region  50 C, while exposing the region  50 D, and appropriate type (e.g., n-type or p-type) impurities may be implanted into the exposed fins  58  in the region  50 D. The mask may then be removed. Subsequently, a mask, such as a photoresist, may be formed over the region  50 D while exposing the region  50 C, and appropriate type impurities may be implanted into the exposed fins  52  in the region  50 C. The mask may then be removed. The n-type impurities may be the any of the n-type impurities previously discussed, and the p-type impurities may be the any of the p-type impurities previously discussed. The lightly doped source/drain regions may have a concentration of impurities of from about 10 15  cm −3  to about 10 16  cm −3 . An anneal may be used to activate the implanted impurities. 
     In  FIGS.  12 A,  12 B, and  12 C , gate spacers  74  are formed on the gate seal spacers (not explicitly illustrated) along sidewalls of the dummy gates  72 . The gate spacers  74  may be formed by conformally depositing a material and subsequently anisotropically etching the material. The material of the gate spacers  74  may be silicon nitride, SiCN, a combination thereof, or the like. 
     In  FIGS.  13 A,  13 B,  13 C,  14 A,  14 B, and  14 C  epitaxial source/drain regions  82  are formed in the fins  52 . The epitaxial source/drain regions  82  are formed in the fins  58  such that each dummy gate  72  is disposed between respective neighboring pairs of the epitaxial source/drain regions  82 . In some embodiments that epitaxial source/drain regions  82  may extend into the fins  52 . In some embodiments, the gate spacers  74  are used to separate the epitaxial source/drain regions  82  from the dummy gates  72  by an appropriate lateral distance so that the epitaxial source/drain regions  82  do not short out subsequently formed gates of the resulting FinFETs. 
     Referring first to  FIGS.  13 A,  13 B, and  13 C , portions of the semiconductor fins  52  are etched, such as portions of the fins  52  not masked by the dummy gates  72  in cross-sections B-B and C-C of  FIG.  1    (see  FIGS.  13 B and  13 C ). Etching the semiconductor fins  52  may recess the semiconductor fins  52  below a top surface of dielectric film  56 . Recessing the fins  52  may use a selective etch process which etches the fins  52  without significantly etching the dummy gates  72  or the dummy fins  62 . In various embodiments, the fins  52  may be recessed separately in the regions  50 B and  50 C, for example, while the other region is masked. 
     In  FIGS.  14 A,  14 B, and  14 C , the epitaxial source/drain regions  82  in the region  50 C, e.g., the NMOS region, may be formed by masking the region  50 D, e.g., the PMOS region, and etching source/drain regions of the fins  58  in the region  50 C form recesses in the fins  58 . Then, the epitaxial source/drain regions  82  in the region  50 C are epitaxially grown in the recesses. The epitaxial source/drain regions  82  may include any acceptable material, such as appropriate for n-type FinFETs. For example, if the fin  58  is silicon, the epitaxial source/drain regions  82  in the region  50 C may include silicon, SiC, SiCP, SiP, or the like. The epitaxial source/drain regions  82  in the region  50 C may have surfaces raised from respective surfaces of the fins  58  and may have facets. In some embodiments, the dummy fins  62  provide physical separation between adjacent ones of the epitaxial source/drain regions  82  in the region  50 C and prevent merging of adjacent epitaxial source/drain regions  82  in the region  50 C during epitaxy. 
     The epitaxial source/drain regions  82  in the region  50 D, e.g., the PMOS region, may be formed by masking the region  50 C, e.g., the NMOS region, and etching source/drain regions of the fins  58  in the region  50 D to form recesses in the fins  58 . Then, the epitaxial source/drain regions  82  in the region  50 D are epitaxially grown in the recesses. The epitaxial source/drain regions  82  may include any acceptable material, such as appropriate for p-type FinFETs. For example, if the fin  58  is silicon, the epitaxial source/drain regions  82  in the region  50 D may comprise SiGe, SiGeB, Ge, GeSn, or the like. The epitaxial source/drain regions  82  in the region  50 D may also have surfaces raised from respective surfaces of the fins  58  and may have facets. In some embodiments, the dummy fins  62  provide physical separation between adjacent ones of the epitaxial source/drain regions  82  in the region  50 D and prevents merging of adjacent epitaxial source/drain regions  82  in the region  50 D during epitaxy. 
     The epitaxial source/drain regions  82  and/or the fins  52  may be implanted with dopants to form source/drain regions, similar to the process previously discussed for forming lightly doped source/drain regions, followed by an anneal. The source/drain regions may have an impurity concentration of between about 10 19  cm −3  and about 10 21  cm −3 . The n-type and/or p-type impurities for source/drain regions may be any of the impurities previously discussed. In some embodiments, the epitaxial source/drain regions  82  may be in situ doped during growth. 
     As a result of the epitaxy processes used to form the epitaxial source/drain regions  82  in the region  50 C and the region  50 D, upper surfaces of the epitaxial source/drain regions  82  have facets which expand laterally outward beyond a sidewalls of the fins  52 . As illustrated in  FIG.  14 B , the upper surfaces of the epitaxial source/drain regions  82  may contact sidewalls of the dummy fins  62 , and the dummy fins  62  may prevent adjacent epitaxial source/drain regions  82  from merging. This may be particularly beneficial in fine-pitched areas (e.g., memory areas) of a chip where different devices are closely spaced together, and the dummy fins  62  may be used to prevent merging of epitaxial source/drain regions  82  of different devices (e.g., an n-type device and a p-type device) that are adjacent to each other. Alternatively as illustrated by  FIG.  14 D , the dummy fins  62  may be etched back prior to forming the epitaxial source/drain regions  82 . For example, a height H 2  of the dummy fins  52  in  FIG.  14 D  may be less than a height H 1  of the dummy fins  52  in  FIGS.  13 B and  14 B . As a result of the etching, the dummy fins  62  do not prevent the merging of adjacent epitaxial source/drain regions. Thus, in  FIG.  14 D , some epitaxial source/drain regions  82  extend over the dummy fins  52  and have a merged profile. Merged epitaxial source/drain regions may be beneficial for enlarging a current transport area of the device, which lowers resistance. In some embodiments, the different profiles of epitaxial source/drain regions  82  and dummy fins  62  in  FIGS.  14 B and  14 D  may be combined in a single die. For example, epitaxial source/drain regions  82  and dummy fins  62  having a configuration (e.g., unmerged source/drain regions) illustrated by  FIG.  14 B  may be found in a first area of a die, and epitaxial source/drain regions  82  and dummy fins  62  having a configuration (e.g., merged source/drain regions) illustrated by  FIG.  14 D  may be found in a second area of a die. In a specific example, the first area of the die is a memory area, and the second area of the die is a logic area. Subsequent embodiments only illustrate unmerged epitaxial source/drain regions  82 ; however, the merged epitaxial source/drain regions  82  described in conjunction with  FIG.  14 D  may also be applied to the subsequent embodiments either in lieu of or in combination with the unmerged epitaxial source/drain regions. 
     In  FIGS.  15 A,  15 B, and  15 C , an ILD  88  is deposited over the structure illustrated in  FIGS.  14 A,  14 B , ad  14 C. The ILD  88  may be formed of a dielectric material, and may be deposited by any suitable method, such as CVD, plasma-enhanced CVD (PECVD), or FCVD. Dielectric materials may include Phospho-Silicate Glass (PSG), Boro-Silicate Glass (BSG), Boron-Doped Phospho-Silicate Glass (BPSG), undoped Silicate Glass (USG), or the like. Other insulation materials formed by any acceptable process may be used. In some embodiments, a contact etch stop layer (CESL), not illustrated, is disposed between the ILD  88  and the epitaxial source/drain regions  82 , the hard mask  70 , and the gate spacers  74 . 
     Subsequently, a planarization process, such as a CMP, may be performed to level the top surface of the ILD  88  with the top surfaces of the dummy gate electrodes  68 . In an embodiment, the planarization process is performed using the planarization system  200 . The planarization process may also remove the masks  74  on the dummy gate electrodes  68 , and portions of the gate seal spacers and the gate spacers  74  along sidewalls of the masks  70 . After the planarization process, top surfaces of the dummy gate electrodes  68 , the gate spacers  74 , and the ILD  88  are level. Accordingly, the top surfaces of the dummy gate electrodes  68  are exposed through the ILD  88 . 
     After planarization, the dummy gate electrodes  68  and portions of the dummy dielectric layer  60  directly underlying the exposed dummy gate electrodes  68  are removed in an etching step(s), so that recesses are formed. In some embodiments, the dummy gate electrodes  68  are removed by an anisotropic dry etch process. For example, the etching process may include a dry etch process using reaction gas(es) that selectively etch dummy gate electrodes  68  without etching the ILD  88  or the gate spacers  74 . Each recess exposes a channel region of a respective fin  52 . Each channel region is disposed between neighboring pairs of the epitaxial source/drain regions  82 . During the removal, the dummy dielectric layer  60  may be used as an etch stop layer when the dummy gate electrodes  68  are etched. The dummy dielectric layer  60  may then be removed after the removal of the dummy gate electrodes  68 . 
     In  FIGS.  16 A,  16 B, and  16 C , gate dielectric layers  92  and gate electrodes  94  are formed for replacement gates. Gate dielectric layers  92  are deposited conformally in the recesses, such as on the top surfaces and the sidewalls of the fins  52 /dummy fins  62  and on sidewalls of the gate seal spacers  74 . The gate dielectric layers  92  may also be formed on top surface of the ILD  88 . In accordance with some embodiments, the gate dielectric layers  92  comprise silicon oxide, silicon nitride, or multilayers thereof. In some embodiments, the gate dielectric layers  92  are a high-k dielectric material, and in these embodiments, the gate dielectric layers  92  may have a k value greater than about 7.0, and may include a metal oxide or a silicate of Hf, Al, Zr, La, Mg, Ba, Ti, Pb, and combinations thereof. The formation methods of the gate dielectric layers  92  may include Molecular-Beam Deposition (MBD), ALD, PECVD, and the like. 
     The gate electrodes  94  are deposited over the gate dielectric layers  92 , respectively. The gate electrodes  94  may be a metal-containing material such as TiN, TaN, TaC, Co, Ru, Al, combinations thereof, or multi-layers thereof. For example, although a single gate electrode  94  is illustrated, any number of work function tuning layers may be deposited in the recesses  90 . After the filling of the gate electrodes  94 , a planarization process, such as a CMP, may be performed to remove the excess portions of the gate dielectric layers  92  and the material of the gate electrodes  94 , which excess portions are over the top surface of the ILD  88 . The remaining portions of material of the gate electrodes  94  and the gate dielectric layers  92  thus form replacement gates of the resulting FinFETs. The gate electrodes  94  and the gate dielectric layers  92  may be collectively referred to as a “gate” or a “gate stack.” The gate and the gate stacks may extend along sidewalls of a channel region of the fins  52  and along sidewalls of the dummy fins  62 . 
     The formation of the gate dielectric layers  92  in the region  50 C and the region  50 D may occur simultaneously such that the gate dielectric layers  92  in each region are formed from the same materials, and the formation of the gate electrodes  94  may occur simultaneously such that the gate electrodes  94  in each region are formed from the same materials. In some embodiments, the gate dielectric layers  92  in each region may be formed by distinct processes, such that the gate dielectric layers  92  may be different materials, and the gate electrodes  94  in each region may be formed by distinct processes, such that the gate electrodes  94  may be different materials. Various masking steps may be used to mask and expose appropriate regions when using distinct processes. 
     In  FIGS.  17 A,  17 B, and  17 C , an ILD  108  is deposited over the ILD  88 . In an embodiment, the ILD  108  is a flowable film formed by a flowable CVD method. In some embodiments, the ILD  108  is formed of a dielectric material such as PSG, BSG, BPSG, USG, or the like, and may be deposited by any suitable method, such as CVD and PECVD. 
     Also in  FIGS.  17 A,  17 B, and  17 C , contacts  110  and  112  are formed through the ILD  108  and the ILD  88  using embodiment contact formation processes. In some embodiments, an anneal process may be performed to form a silicide at the interface between the epitaxial source/drain regions  82  and the contacts  112  prior to the contacts  112  being formed. The contact  110  is physically and electrically connected to the gate electrode  94 , and the contacts  112  are physically and electrically connected to the epitaxial source/drain regions  82 .  FIG.  17 C  illustrate the contacts  110  and  112  in a same cross-section; however, in other embodiments, the contacts  110  and  112  may be disposed in different cross-sections. Further, the position of contacts  110  and  112  in  FIGS.  17 A,  17 B, and  17 B  are merely illustrative and not intended to be limiting in any way. For example, the contact  110  may be vertically aligned with a semiconductor fin  52  as illustrated or may be disposed at a different location on the gate electrode  94 . Furthermore, the contacts  112  may be formed prior to, simultaneously with, or after forming the contacts  110 . 
       FIGS.  17 D,  17 E, and  17 F  illustrate a device where the dielectric film  58  is omitted. In such embodiments, the dummy fins  62  are defined by portions of the dielectric film  60  extending above the dielectric film  56 . Because the dummy fins  62  is defined by a single film, the dummy fins  62  may have a same material composition throughout. Further, a combination of the dielectric film  56 , lower portions of the dielectric film  60 , and voids  61  (if present) may provide isolation between adjacent semiconductor fins  52 . 
       FIGS.  18  through  22    illustrate cross sectional views of intermediary steps of manufacturing a device in accordance with other embodiments. Unlike the embodiments of  FIGS.  2  through  9   , in  FIGS.  18  through  22   , the mask layer  54  is removed (e.g., using a suitable planarization or etch back process) prior to the formation of the dielectric film  56 . In such embodiments, the dielectric film  56  may be formed directly on a top surface of the semiconductor fins  52  without any intervening mask layers  54 . Subsequent processing may be substantially similar to the embodiment of  FIGS.  2  through  9    where like reference numerals indicate like elements formed using like processes. For example, in  FIG.  19   , an optional dielectric film  58  is deposited over the dielectric film  56 . In  FIG.  20   , a dielectric material  60  is deposited over the dielectric film  56  and the dielectric film  58  (if present). The dielectric material  60  is deposited to at least partially fill areas between the semiconductor fins  52 , and the dielectric material  60  is further deposited to overfill and cover the dielectric films  56  and  58  (if present). In  FIG.  21   , a planarization process is applied to the dielectric material  60  to expose top surfaces of the fins  52 , the dielectric film  56 , and the dielectric film  58  (if present). Although  FIG.  21    illustrates the fins  52 , the dielectric film  56 , the dielectric film  58 , and the dielectric material  60  as being co-planar after planarization, in other embodiments, these top surfaces may be non-planar (e.g., as illustrated by  FIG.  7 B ). Subsequently, in  FIG.  22   , an etch back process is performed on the dielectric film  56  to define semiconductor fins  52  and dummy fins  62  (e.g., comprising upper portions of the dielectric film  58  (if present) and of the dielectric material  60 ). After the semiconductor fins  52  and the dummy fins  62  are formed (see  FIG.  22   ), additional process steps, similar to those discussed above with respect to  FIGS.  10 A through  17 C  may be performed in order to form functional finFET devices. Although  FIGS.  18  through  22    illustrate the inclusion of optional dielectric film  58 , in other embodiments dielectric film  58  may be excluded and the dielectric material  60  may be deposited directly on the dielectric film  56 . 
       FIGS.  23  through  27    illustrate cross sectional views of intermediary steps of manufacturing a device in accordance with other embodiments.  FIG.  23    illustrates a cross-sectional at a stage of manufacture similar to  FIG.  6    where like reference numerals indicate like elements formed using like processes. Although  FIG.  23    illustrates the inclusion of dielectric film  58 , dielectric film  58  is optional. In other embodiments, dielectric film  58  is excluded (see e.g.,  FIGS.  28 D,  28 E, and  28 F ). 
     In  FIG.  24   , an etch back process is used to pattern the dielectric material  60  such that the dielectric film  58  (if present) or the dielectric film  56  (if optional dielectric film  58  is excluded) is exposed. In  FIG.  25   , a dielectric material  202  is deposited over the dielectric film  56  and dielectric film  58  (if present). In some embodiments, the dielectric material  202  may be deposited using a flowable deposition process, a spin-on process, or the like. The dielectric material  202  may comprise a carbon-containing dielectric film (e.g., a carbon-containing oxide, such as, SiOC), a metal-containing dielectric film (e.g., a metal-containing oxide, such as, a combination of SiO and a metal), or the like. In some embodiments, a carbon and/or metal percentage by weight of the dielectric material  60  is less than a corresponding carbon/metal percentage by weight of the dielectric liner  58 . For example, the dielectric liner  58  may comprise SiOC with more than 10% by weight of carbon, and the dielectric material  60  may comprise SiOC with less than 10% by weight of carbon. A material composition of the dielectric material  202  and the dielectric material  60  may be the same or different. For example, the dielectric material  202  and the dielectric material  60  may have a same percentage by weight of carbon/metal or a different percentage by weight of carbon/metal. In some embodiments, the dielectric material  202  provides additional protection for and encapsulates the dielectric material  60 . 
     In  FIG.  26   , a planarization (e.g., a CMP and/or etch back process (e.g., a dry etching process)) is used to expose upper surfaces of the dielectric film  56 . In some embodiments, exposing the dielectric film  56  results in upper surfaces of the dielectric material  202  and the dielectric film  56  being substantially coplanar. 
     In  FIG.  27   , an additional etch back process is performed on the dielectric liner  56 . The dielectric liner  56  is recessed such that semiconductor fins  52  and dummy fins  62  protrude above top surfaces of the etched dielectric liner  56 . After the dielectric liner  56  is recessed, the hard mask  54  may also be removed from top surfaces of the fins  52  using, for example, an acceptable etching process. In some embodiments, after recessing, a height of the semiconductor fins  52  may be less than a height of the dummy fins  62 . Dummy fins  62  are made of upper portions of the dielectric liner  58  (if present), upper portions of the dielectric material  60 , and remaining portions of the dielectric material  202 . Thus, dummy fins  62  may have a different material composition than semiconductor fins  52  and may be insulating fins. Further, remaining portions of the dielectric liner  56 , lower portions of the dielectric liner  58 , and lower portions of the dielectric material  60  (referred to collectively as isolation region  64 ) provide electrical isolation between adjacent fins  52  and may further provide STI regions between the fins  52  such that an separate STI region need not be formed. 
     In other embodiments, a separate STI region is formed (e.g., between a bottom surface of the dielectric film  56  and the substrate  50 ). For example,  FIG.  31    illustrates an embodiment where a separate STI region  204  is formed between bottoms of the dielectric film  56  and the substrate  50  (labeled as  50 A). In the embodiment of  FIGS.  30 A,  30 B, and  30 C , individual fins  52  may be connected by a mesa  50 A (sometimes referred to as a crown). Mesa  50 A is a portion of the substrate  50 . Multiple fins  52  may extend from a single mesa  50 A, which is connected to a lower portion of the substrate  50  (labeled as  50 B). Mesa  50 A may provide improved structural stability in the formation of high aspect ratio fins (e.g., fins  52 ). STI region  204  may be formed to extend along lower portions of the fins  52  as well as along sidewalls of the mesa  50 A. Although subsequent figures illustrate embodiments where the mesa  50 A and STI region  204  are excluded, this is for ease of illustration only. It should be recognized that the embodiment of  FIG.  31    may be incorporated into subsequent process steps and combined with subsequent descriptions. For example,  FIGS.  32 A,  32 B, and  32 C  illustrate a finFET device after further processing, e.g., using similar processes as described below in  FIGS.  10 A through  17 C  where like reference numerals indicate like elements formed using like processes, incorporating a separate STI region and the dielectric film  202  as described with respect to  FIG.  31   .  FIG.  32 A  is taken along reference cross-section A-A of  FIG.  1   ;  FIG.  32 B  is taken along reference cross-section B-B of  FIG.  1   ; and  FIG.  32 C  is taken along reference cross-section C-C of  FIG.  1   . 
     In some embodiments, etching back the dielectric liner  56  may use a selective etching process which selectively etches the dielectric liner  56  at a faster rate than the dielectric liner  58 , the dielectric material  60 , and the fins  52 . Such selective etching may be enabled, for example, by the inclusion of carbon and/or a metal in the dielectric liner  58  and the dielectric material  60 . 
     After the semiconductor fins  52  and the dummy fins  62  are formed (see  FIG.  27   ), additional process steps, similar to those discussed above with respect to  FIGS.  10 A through  17 C  may be performed in order to form functional finFET devices. The resulting structures are illustrated in  FIG.  28 A  (illustrating a device along a similar cross section as A-A in  FIG.  1   ),  28 B (illustrating a device along a similar cross section as A-A in  FIG.  1   ), and  28 C (illustrating a device along a similar cross section as A-A in  FIG.  1   ) where like reference numerals indicate like elements formed using like processes. Further, because dummy fins  62  extend above the semiconductor fins  62 , the dummy fins  62  may be even more effective in reducing the merging of adjacent source/drain epitaxial regions  82 . Although  FIGS.  23  through  27    illustrate the removal of the mask layer  54  after forming the dielectric material  202 , in other embodiments, the mask layer  54  may be removed prior to the deposition of the dielectric film  56  (e.g., as depicted in  FIG.  18   ). In such embodiments, the dielectric film  56  may be formed directly on sidewalls and a top surface of the fins  52  (see  FIG.  18   ). 
       FIGS.  28 D,  28 E, and  28 F  illustrate a device similar to the device depicted in  FIGS.  28 A,  28 B, and  28 C  where the dielectric film  58  is omitted. In  FIGS.  28 D,  27 E, and  27 F , like reference numerals indicate like elements formed by like processes as  FIGS.  28 A,  28 B, and  28 C . In such embodiments, the dummy fins  62  are defined by portions of the dielectric film  60  extending above the dielectric film  56  and the dielectric material  202 . Further, a combination of the dielectric film  56 , lower portions of the dielectric film  60 , and voids  61  (if present) may provide isolation between adjacent semiconductor fins  52 . 
     In accordance with an embodiment, a method includes depositing a first dielectric film over and along sidewalls of a semiconductor fin, the semiconductor fin extending upwards from a semiconductor substrate; depositing a dielectric material over the first dielectric film; recessing the first dielectric film below a top surface of the semiconductor fin to define a dummy fin, the dummy fin comprising an upper portion of the dielectric material; and forming a gate stack over and along sidewalls of the semiconductor fin and the dummy fin. In an embodiment, depositing the dielectric material comprises covering a top surface of the first dielectric film with the dielectric material, the method further comprising planarizing the dielectric material to expose the first dielectric film. In an embodiment, depositing the dielectric material comprises defining a void under the dielectric material between the semiconductor fin and a second semiconductor fin. In an embodiment, recessing the first dielectric film comprises etching the first dielectric film at a faster rate than the dielectric material. In an embodiment, the method further includes prior to depositing the dielectric material, depositing a second dielectric film over the first dielectric film, and wherein the dummy fin comprises an upper portion formed of the second dielectric film. In an embodiment, the method further includes prior to recessing the first dielectric film, recessing the dielectric material below a topmost surface of the first dielectric film; depositing a second dielectric material over the dielectric material and the first dielectric film; and planarizing the second dielectric material to expose the first dielectric film. In an embodiment, the method further includes patterning the semiconductor substrate using a mask layer to define the semiconductor fin, wherein the first dielectric film is deposited over and along sidewalls of the mask layer. In an embodiment, the method further includes patterning the semiconductor substrate using a mask layer to define the semiconductor fin; and prior to depositing the first dielectric film, removing the mask layer. 
     In accordance with an embodiment, a device includes a first semiconductor fin and a second semiconductor fin extending upwards from a semiconductor substrate; an isolation region comprising a first dielectric film and disposed between the first semiconductor fin and the second semiconductor fin; a dummy fin extending upwards from the isolation region, wherein the dummy fin comprises a first dielectric material extending from below a topmost surface of the first dielectric film to above the topmost surface of the first dielectric film; and a gate stack disposed over and extending along sidewalls of the first semiconductor fin, over and along sidewalls of the second semiconductor fin, and over and along sidewalls of the dummy fin. In an embodiment, the first dielectric film comprises silicon oxide, and wherein the first dielectric material comprises a carbon containing oxide, a metal containing oxide, or a combination thereof. In an embodiment, the dummy fin comprises a second dielectric film disposed between the first dielectric film and the first dielectric material. In an embodiment, a carbon percentage by weight of the second dielectric film is greater than a carbon percentage by weight of the first dielectric material. In an embodiment, a metal percentage by weight of the second dielectric film is greater than a metal percentage by weight of the first dielectric material. In an embodiment, the dummy fin further comprises a second dielectric material covering a top surface of the first dielectric material. In an embodiment, top surfaces of the dummy fin and the first semiconductor fin are substantially level. In an embodiment, the dummy fin extends higher than the first semiconductor fin. In an embodiment, the device further includes a semiconductor mesa connecting the first semiconductor fin and the second semiconductor fin, wherein the isolation region further comprises a third dielectric material disposed between the first dielectric film and the semiconductor mesa, and wherein the third dielectric material further extends along sidewalls of the semiconductor mesa. In an embodiment, the device further includes a second dummy fin disposed on an opposing side of the first semiconductor fin as the dummy fin, wherein the second dummy fin extends upwards from the isolation region, wherein the second dummy fin comprises the first dielectric material; and a source/drain region disposed between the dummy fin and the second dummy fin. 
     In accordance with an embodiment, a method includes depositing a first dielectric film over and along sidewalls of a plurality of semiconductor fins; depositing a dielectric material over the first dielectric film, wherein the dielectric material comprises carbon, metal, or a combination thereof, and wherein the dielectric material is deposited between each of the plurality of semiconductor fins; planarizing the dielectric material to expose the first dielectric film; etching the first dielectric film using an etchant that etches the first dielectric film at a faster rate than the dielectric material, wherein etching the first dielectric film defines a plurality of dummy fins extending above a top surface of the first dielectric film, and wherein the plurality of dummy fins comprises at least a portion of the dielectric material; and forming a gate stack over and along sidewalls of the plurality of semiconductor fins and over and along sidewalls of the plurality of dummy fins. In an embodiment, the method further includes prior to depositing the dielectric material, depositing a second dielectric film over the first dielectric film, wherein the second dielectric film comprises carbon, metal or a combination thereof, and wherein the plurality of dummy fins comprises at least a portion of the second dielectric film. 
     The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.