Patent Publication Number: US-2015084187-A1

Title: Methods of forming hydrophobic surfaces on semiconductor device structures, methods of forming semiconductor device structures, and semiconductor device structures

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 13/464,645, filed May 4, 2012, pending, the disclosure of which is hereby incorporated herein in its entirety by this reference. 
    
    
     TECHNICAL FIELD 
     Embodiments of the disclosure relate to the field of semiconductor device design and fabrication. More specifically, the disclosure, in various embodiments, relates to methods of forming hydrophobic surfaces on semiconductor device structures, methods of forming semiconductor device structures, and to semiconductor device structures. 
     BACKGROUND 
     A continuing goal of integrated circuit fabrication is to increase integration density. One approach used to achieve increased integration density involves reducing the lateral footprint of individual structures by increasing the aspect ratio (i.e., ratio of height to width or diameter) of the individual structures and the proximity of adjacent structures. However, one problem with this approach is that spaces between closely adjacent high aspect ratio (HAR) structures can act as capillaries during post-formation processes (e.g., “release-related” processes such as cleaning, rinsing, and drying, and “in-use” processes such as post-drying processes), such that liquid (e.g., water) is drawn into such spaces. High surface tension forces resulting from the liquid in the spaces between adjacent HAR structures can cause the adjacent HAR structures to topple or collapse toward each other, bringing the adjacent HAR structures into contact with each other. The gap between the adjacent HAR structures can produce surface forces (e.g., Van der Waals, electrostatic, hydrogen bonding, capillary, solid bridging, etc.) that cause the adjacent HAR structures to statically adhere to each other. Such static adhesion is commonly referred to in the art as “stiction.” Stiction between the adjacent HAR structures can substantially impede desired functions of a semiconductor device structure or even render the semiconductor device structure inoperable (e.g., by substantially damaging components of the semiconductor device structure). 
     A need, therefore, exists for new, simple, and cost-efficient methods of reducing stiction between adjacent HAR structures of a semiconductor device structure. It would be further desirable for the new methods to be applicable to the formation of a variety of semiconductor device structures. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIGS. 1A through 1D  are partial cross-sectional views of a semiconductor device structure and illustrate various stages of a method of forming a plurality of capacitors in accordance with embodiments of the disclosure; 
         FIG. 2A and 2B  are partial cross-sectional views of a semiconductor device structure and illustrate various stages of another method of forming a plurality of capacitors in accordance with embodiments of the disclosure; 
         FIG. 3  is an X-ray photoelectron spectroscopy (XPS) survey spectrum showing the surface chemistry of a surface modified using an embodiment of the method of the disclosure, as described in Example 1; 
         FIGS. 4A and 4B  are, respectively, positive mode and negative mode survey mass spectra showing the chemistry of films formed on titanium nitride surfaces using an embodiment of the method of the disclosure, as described in Example 2; 
         FIGS. 5A through 8B  are graphs illustrating the thermal desorption profiles of select positive ions and select negative ions for a control sample and for multiple coupon samples formed using an embodiment of the method of the disclosure, as described in Example 2; 
         FIGS. 9A and 9B  are graphs respectively illustrating the C 2 H 3  thermal desorption profiles and the PO 2   −  thermal desorption profiles for a control sample and for multiple coupon samples formed using an embodiment of the method of the disclosure, as described in Example 2; 
         FIGS. 10A through 10C  are photographs showing the contact angle of an uncleaned titanium nitride surface, a clean titanium nitride surface, and a titanium nitride surface modified with a film formed using an embodiment of the method of the disclosure, respectively, as described in Example 3; 
         FIG. 11  is a scanning electron micrograph (SEM) showing a top-down view of a plurality of structures of a semiconductor device structure, as described in Example 4; 
         FIGS. 12A and 12B  are SEMs showing a plurality of structures formed using conventional methods, as described in Example 4; and 
         FIGS. 13A and 13B  are SEMs showing a plurality of structures formed using an embodiment of the method of the disclosure, as described in Example 4. 
     
    
    
     DETAILED DESCRIPTION 
     Semiconductor device structures including at least one hydrophobic surface are disclosed, as are methods of forming such structures and devices. The hydrophobic surface may be formed by exposing at least one structure having titanium exposed on a surface thereof with a plurality of precursor compounds to form a hydrophobic material on the at least one structure. By modifying the exposed surface of the at least one structure, the surface of the at least one structure may become hydrophobic. Each of the plurality of precursor compounds includes a reactive head group (e.g., a phosphonate group, or a phosphate group) that may react with and attach to a titanium atom of the at least one structure, and a hydrophobic tail group (e.g., a hydrocarbon group) that may form a portion of the hydrophobic surface. The hydrophobic material may be used as at least one of an anti-stiction material, a passivation material, and a lubricant for the at least one structure. As used herein, the term “anti-stiction material” means and includes a material that substantially limits or even prevents adhesion of adjacent structures by effecting at least one of forces resulting in the contact of the adjacent structures (e.g., adhesion forces between the adjacent structures and a liquid moving between the adjacent structures) and forces adhering the adjacent structures to each other upon contact. For example, the hydrophobic material may decrease the surface energy of adjacent structures of plurality of structures to substantially reduce surface forces which may otherwise result in contact and adhesion of the adjacent structures. The hydrophobic material may be incorporated into a semiconductor device structure, such as a dynamic random access memory (DRAM) structure, a NAND structure, and a microelectromechanical system (MEMS) structure. 
     The following description provides specific details, such as material types, material thicknesses, and processing conditions in order to provide a thorough description of embodiments of the disclosure. However, a person of ordinary skill in the art will understand that the embodiments of the disclosure may be practiced without employing these specific details. Indeed, the embodiments of the disclosure may be practiced in conjunction with conventional fabrication techniques employed in the industry. In addition, the description provided below does not form a complete process flow for manufacturing a semiconductor device. The semiconductor device structures described below do not form a complete semiconductor device. Only those process acts and structures necessary to understand the embodiments of the disclosure are described in detail below. Additional acts to form the complete semiconductor device from semiconductor device structures may be performed by conventional fabrication techniques. Also note, any drawings accompanying the present application are for illustrative purposes only, and are thus not drawn to scale. Additionally, elements common between figures may retain the same numerical designation. 
     As used herein, relational terms, such as “first,” “second,” “top,” “bottom,” “upper,” “lower,” “over,” “under,” etc., are used for clarity and convenience in understanding the disclosure and accompanying drawings and does not connote or depend on any specific preference, orientation, or order, except where the context clearly indicates otherwise. 
       FIGS. 1A through 1D , are simplified partial cross-sectional views illustrating embodiments of a method of forming a semiconductor device structure that includes forming hydrophobic surfaces on a plurality of structures. With the description as provided below, it will be readily apparent to one of ordinary skill in the art that the methods described herein may be used in various applications. In other words, the methods of the disclosure may be used whenever it is desired to increase the hydrophobicity and/or reduce the surface energy of at least a portion of at least one structure. 
     Referring to  FIG. 1A , a semiconductor device structure  100  may include a substrate  102 , a plurality of structures  104 , and a retaining structure  106 . The plurality of structures  104  may be located in, on, or over the substrate  102 . As used herein, the term “substrate” means and includes a base material or construction upon which additional materials are formed. The substrate  102  may be a semiconductor substrate, a base semiconductor layer on a supporting structure, a metal electrode or a semiconductor substrate having one or more layers, structures or regions formed thereon. The substrate  102  may be a conventional silicon substrate or other bulk substrate comprising a layer of semiconductive material. As used herein, the term “bulk substrate” means and includes not only silicon wafers, but also silicon-on-insulator (SOI) substrates, such as silicon-on-sapphire (SOS) substrates and silicon-on-glass (SOG) substrates, epitaxial layers of silicon on a base semiconductor foundation, and other semiconductor or optoelectronic materials, such as silicon-germanium, germanium, gallium arsenide, gallium nitride, and indium phosphide. The substrate  102  may be doped or undoped. As depicted in  FIG. 1A , in one or more embodiments, electrically conductive structures  108  may be located between the substrate  102  and the plurality of structures  104 . The electrically conductive structures  108  may be, for example, at least one of doped regions of the substrate  102  and pedestals of a conductive material (e.g., a conductive metal material) located in, on, or over the substrate  102 . 
     The retaining structure  106  (also referred to as a “lattice structure”) may be located over at least a portion of each of the plurality of structures  104 , such as over an upper region  110  of sidewalls  112  of each of the plurality of structures  104 . The retaining structure  106  may be configured to provide structural support to each of the plurality of structures  104 . By way of non-limiting example, the retaining structure  106  may substantially limit or prevent at least one of toppling, collapse, and wobbling of each of the plurality of structures  104 . The retaining structure  106  may include a plurality of holes or vias facilitating access to spaces between adjacent structures of the plurality of structures  104 . The retaining structure  106  may have any desired thickness, such as a thickness within a range of from about 50 Å to about 3000 Å, or from about 50 Å to about 1000 Å. The retaining structure  106  may be substantially homogeneous (e.g., formed of and including a single, substantially uniform material composition), or may be substantially heterogeneous (e.g., formed of and including at least one of a non-uniform material composition, and a plurality of material compositions). The retaining structure  106  may be formed of and include at least one of silicon nitride (SiN) and a silicon oxide. In at least some embodiments, the retaining structure is formed of and includes SiN. While in  FIG. 1A  it may appear as though retaining structure  106  is floating, the retaining structure  106  is supported by regions of the semiconductor device structure  100  that are not visible in the cross-section shown in  FIG. 1A . Such supporting regions may be analogous to those shown and described in U.S. Patent Publication No. 2005/0054159, now U.S. Pat. No. 7,125,781, issued Oct. 24, 2006. 
     As shown in  FIG. 1A , each of the plurality of structures  104  may be a container-shaped structure, including a sidewall or sidewalls  112  integral with a floor  114 . For example, a cylindrical container-shaped structure may have only a single, continuous sidewall  112 , while a polygonal-shaped container structure may have a plurality of sidewalls  112 . Inner sidewall surfaces  116  and an upper floor surface  118  of each of the plurality of structures  104  define openings  120  bounded by the sidewall or sidewalls  112  of each of the plurality of structures  104 . In additional embodiments, each of the plurality of structures  104  may be of a different shape including, but not limited to, one of a rectangular column, a cylindrical column, a dome, a pyramid, a frusto pyramid, a cone, a frusto cone, a fin, a pillar, a stud, and an irregular shape. Accordingly, each of the plurality of structures  104  may have a desired lateral cross-sectional shape including, but not limited to, an annular shape, a circular shape, a tetragonal shape (e.g., square, rectangular, trapezium, trapezoidal, parallelogram, etc.), a triangular shape, a semicircular shape, an ovular shape, and an elliptical shape. In at least some embodiments, the lateral cross-sectional shape of each of the plurality of structures  104  is substantially annular. 
     The dimensions of each of the plurality of structures  104  may be varied as desired. By way of non-limiting example, as shown in  FIG. 1A , at least where each of the plurality of structures  104  has a container-shaped structure, a diameter D 1  (or width) of each of the plurality of structures  104  may be less than or equal to about 650 Angstroms (Å), such as less than or equal to about 400 Å, or less than or equal to about 200 Å. In at least some embodiments, the diameter D 1  of each of the plurality of structures  104  is within a range of from about 400 Å to about 650 Å. By way of additional non-limiting example, at least where each of the plurality of structures  104  has a container-shaped structure, a height H 1  of the plurality of structures  104  may be greater than or equal to about 1.0×10 4  Å, such as greater than or equal to about 1.5×10 4  Å, or greater than or equal to about 2.0×10 4  Å. In at least some embodiments, the height H 1  of each of the plurality of structures  104  is within a range of from about 1.0×10 4  Å to about 2.0×10 4  Å. Each of the plurality of structures  104  may be a high aspect ratio (HAR) structure. As used herein, the term “high aspect ratio structure” means and includes that the height of the structure is greater than or equal to five times a diameter, or width, of the structure (i.e., the structure has an aspect ratio of greater than or equal to 5:1). For example, an aspect ratio of each of the plurality of structures  104  may be within a range of from about 5:1 to about 100:1, such as from about 10:1 to about 50:1, or from about 20:1 to about 30:1. In addition, as shown in  FIG. 1A , if each of the plurality of structures  104  as a container-shaped structure, the sidewalls  112  of each of the plurality of structures  104  may have a thickness T 1  within a range of from about 40 Å to about 100 Å, such as from about 55 Å to about 80 Å, or from about 60 Å to about 70 Å. In at least some embodiment, the thickness T 1  of each the sidewalls  112  is about 65 Å. 
     Each of the plurality of structures  104  may be formed of and include at least one of a titanium material, a zirconium material, and a hafnium material. By way of non-limiting example, each of the plurality of structures  104  may be formed of and include at least one of elemental titanium (Ti), titanium nitride (TiN), titanium carbide (TiC), a titanium silicide (e.g., TiSi, TiSi 2 ), a titanium oxide (e.g., TiO, TiO 2 ), a titanium alloy (e.g., an alloy including titanium and at least one of zinc, cadmium, mercury, aluminum, gallium, indium, tin, silicon, germanium, lead, arsenic, and antimony). Accordingly, each of the plurality of structures  104  may be considered to be a titanium-containing structure. The titanium material of the structures  104  is hydrophilic, thus making the structures  104  susceptible to stiction. In at least some embodiments, each of the plurality of structures  104  is formed of and includes TiN. 
     Each of the plurality of structures  104  may be disposed at select locations across a surface of the substrate  102 . By way of non-limiting example, the plurality of structures  104  may be disposed in an ordered array over and in contact with the substrate  102 . The ordered array may include a plurality of rows and a plurality of columns across the surface of the substrate  102 . The plurality of rows may run in a direction substantially perpendicular to the plurality of columns. In additional embodiments, each of the plurality of structures  104  may be disposed at random locations across the surface of the substrate  102 . 
     The plurality of structures  104  may be substantially isolated from one another, such that at least a majority of the plurality of structures  104  do not contact an adjacent structure of the plurality of structures  104 . As shown  FIG. 1A , in one or more embodiments, adjacent structures of the plurality of structures  104  may be separated or spaced by a distance S 1  of less than or equal to about 650 Å, such less than or equal to about 400 Å, or less than or equal to about 200 Å. The distance S 1  between the adjacent structures may be, for example, within a range of from about 200 Å to about 600 Å. As shown in  FIG. 1A , at least where each of the plurality of structures  104  is a container-shaped structure, outer sidewall surfaces  122  of the adjacent structures of the plurality of structures  104 , a bottom surface  124  of the retaining structure  106 , and a top surface  126  of the substrate  102  may define capillaries  128  between the adjacent structures. 
     The semiconductor device structure  100  may be formed using conventional techniques and conventional processing equipment (not shown), which are not described in detail herein. As a non-limiting example, the semiconductor device structure  100  may be formed using techniques substantially similar to those shown and described in U.S. Patent Publication No. 2005/0054159, now U.S. Pat. No. 7,125,781, issued Oct. 24, 2006. 
     Following the formation of the semiconductor device structure  100 , the semiconductor device structure  100  may be cleaned and rinsed using conventional techniques and processing equipment, which are not described in detail herein. By way of non-limiting example, the semiconductor device structure  100  may be exposed to an aqueous halogen acid (e.g., hydrofluoric acid), followed by exposure to tetramethylammonium hydroxide (TMAH), followed by another exposure to an aqueous halogen acid (e.g., hydrofluoric acid), followed by at least one rinse with one or more of deionized water and isopropanol. 
     Referring to  FIG. 1B , a hydrophobic material  130  may be formed (e.g., by way of spin coating, spray coating, dip coating, immersion, soaking, steeping, etc.) over and in contact with at least exposed surfaces of each of the plurality of structures  104  (e.g., the inner sidewall surfaces  116 , the upper floor surface  118 , and exposed portions of the outer sidewall surfaces  122 ). The hydrophobic material  130  may be formed substantially continuously across the exposed surfaces of the plurality of structures  104 . The hydrophobic material  130  may substantially conform to the exposed surfaces of the plurality of structures  104 . As shown in  FIG. 1B , the hydrophobic material  130  may be selectively formed over and in contact with the exposed surfaces of the plurality of structures  104  such that other exposed surfaces of the semiconductor device structure  100  (e.g., exposed surfaces of the substrate  102  and exposed surfaces of the retaining structure  106 ) remain substantially free of the hydrophobic material  130  (i.e., the hydrophobic material  130  is not substantially formed over and in contact with the other exposed surfaces of the semiconductor device structure  100 ). In additional embodiments, the hydrophobic material  130  may be formed over and in contact with the exposed surfaces of the plurality of structures  104  and over and in contact with at least one of the other exposed surfaces of the semiconductor device structure  100  (e.g., at least one of the exposed surfaces of the substrate  102  and the exposed surfaces of the retaining structure  106 ). 
     The hydrophobic material  130  may be formed of and include a plurality of hydrophobic compounds attached to the plurality of structures  104 . The hydrophobic material  130  may be a monolayer of the plurality of hydrophobic compounds. Each of the plurality of hydrophobic compounds may include a polar head group bonded (e.g., by way of a covalent bond) with a Ti atom of the plurality of structures  104  and a hydrophobic tail group directly bonded to the polar head group. The polar head group may be a phosphonate group or a phosphate group. The hydrophobic tail group may be a hydrocarbon group, such as an aliphatic group, a cyclic group, or a combination thereof As used herein, the term “aliphatic group” means and includes a saturated or unsaturated, linear or branched hydrocarbon group, such as an alkyl group, an alkenyl group, or an alkynyl group. A suitable alkyl group may be a saturated, linear or branched hydrocarbon group including from 6 carbon atoms to 18 carbon atoms, such as hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, or octadecyl. A suitable alkenyl group may be an unsaturated, linear or branched hydrocarbon group including from 6 carbon atoms to 18 carbon atoms and at least one carbon-carbon double bond. A suitable alkynyl group may be an unsaturated, linear or branched hydrocarbon group including from 6 carbon atoms to 18 carbon atoms and at least one carbon-carbon triple bond. As used herein, the term “cyclic group” means and includes at least one closed ring hydrocarbon group, such as an alicyclic group, an aryl group, or a combination thereof. A suitable alicyclic group may be a closed ring hydrocarbon group including from 5 to 8 carbons, such as cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, or alkyl-substituted derivatives thereof. A suitable aryl group may include a closed aromatic ring or closed aromatic ring system including from 6 carbon atoms to 22 carbon atoms such as phenyl, biphenyl, naphthyl, anthryl, or alkyl-substituted derivatives thereof Suitable combinations of aliphatic groups and cyclic groups may include, for example, alkyl-substituted aryl groups, and arylalkyl groups. The hydrophobic tail groups of the plurality of hydrophobic compounds facilitate the formation of hydrophobic surfaces  132  on the hydrophobic material  130 . For example, a terminal methyl group of the hydrophobic tail group of each of the plurality of hydrophobic compounds may form a portion of the hydrophobic surfaces  132 . The terminal methyl group may also enable the hydrophobic surfaces  132  to have a relatively low coefficient of friction. In addition, at least one of Van der Waals attractions between hydrophobic tail groups of adjacent hydrophobic compounds, pi-pi orbital interaction between adjacent conjugated moieties, and intermolecular cross-linking may enhance the stability and mechanical integrity of the hydrophobic material  130 . Each of the plurality of hydrophobic compounds in the hydrophobic material  130  may be the same, or at least one of the plurality of hydrophobic compounds may be different than at least one other of the plurality of hydrophobic compounds. The hydrophobic material  130  may exhibit a high degree of molecular order. 
     Accordingly, a method of forming a semiconductor device structure may comprise forming adjacent structures comprising exposed titanium atoms. A hydrophobic material comprising a plurality of hydrophobic compounds may be formed on the plurality of structures. Each of the plurality of hydrophobic compounds may have a phosphate group bonded to an exposed titanium atom of the adjacent structures. 
     Furthermore, a semiconductor device structure of the disclosure may include at least one structure comprising titanium, and a hydrophobic material over at least one structure and comprising a plurality of hydrophobic compounds. Each of the hydrophobic compounds may comprise a polar head group bonded to a titanium atom of the at least one structure, and a hydrophobic tail group bonded to the polar head group and comprising a hydrocarbon group. 
     The hydrophobic material  130  may be formulated and configured such that the hydrophobic surfaces  132  form a contact angle of greater than about ninety degrees (90°) with an aqueous solution, such as greater than or equal to about one-hundred degrees (100°) with the aqueous solution, or greater than or equal to about one-hundred and ten degrees (110°) with the aqueous solution, or greater than or equal to about one-hundred and twenty degrees (120°) with the aqueous solution. As used herein, the term “hydrophobic surface” means and includes a surface exhibiting a contact angle of greater than or equal to about ninety-degrees (90°) when measured in accordance with ASTM Test Method D7334-08, entitled  Standard Practice For Surface Wettabiltiy of Coatings, Substrates and Pigments by Advancing Contact Angle Measurement.  As used herein, the term “contact angle” means and includes the angle between a liquid-solid interface and a plane tangent to the liquid-gas interface at a point where a droplet of liquid (e.g., water) meets the solid surface. As used herein, the term “aqueous solution” means and includes a solution of at least one solute in water, a suspension of at least one solute in water, an emulsion of at least one solute in water, combinations thereof, or water substantially free of solute. 
     A thickness of the hydrophobic material  130  may be such that the hydrophobic material  130  does not substantially alter the distance S 1  between the adjacent structures of the plurality of structures  104 . The thickness of the hydrophobic material  130  at least partially depends on the molecular size and orientation of the plurality of hydrophobic compounds. By way of non-limiting example, at least where the hydrophobic tail group of each of the plurality of hydrophobic compounds is an aliphatic group including from 6 carbon atoms to 18 carbon atoms, the thickness of the hydrophobic material  130  may be within a range of from about 10 Å to about 25 Å. In at least some embodiments, the thickness of the hydrophobic material  130  is within a range of from about 10 Å to about 12 Å. 
     An orientation of the hydrophobic tail group of each of the plurality of hydrophobic compounds of the hydrophobic material  130  may approach a direction perpendicular to that of a surface to which the hydrophobic compound is attached. By way of non-limiting example, the orientation of each of the plurality of hydrophobic compounds may be from about ten degrees (10°) off-perpendicular to about thirty degrees (30°) off-perpendicular, or from about fifteen degrees (15°) off-perpendicular to about twenty-five degrees (25°) off-perpendicular. As used herein, the term “off-perpendicular” means and includes the number of degrees that a hydrophobic tail group of a hydrophobic compound is angled from a direction substantially perpendicular to a surface to which the cross-linked hydrophobic compound is bound or attached. In at least some embodiments, each of the plurality of hydrophobic compounds of the hydrophobic material  130  is about twenty degrees (20°) off-perpendicular. The hydrophobic tail groups of the plurality of hydrophobic compounds may be closely packed and oriented parallel to each other such that the hydrophobic material  130  exhibits stiffness in a direction parallel to an underlying surface of the semiconductor device structure  100  (e.g., an underlying surface of the plurality of structures  104 ). 
     To form the hydrophobic material  130 , the semiconductor device structure  100  may be exposed to a plurality of precursor compounds that interact with the Ti atoms on the exposed surfaces of the plurality of structures  104  to form the plurality of hydrophobic compounds described above. Each of the plurality of precursor compounds may include a reactive head group and a hydrophobic tail group directly bonded to the reactive head group. The reactive head group of each of the plurality of precursor compounds becomes the polar head group of each of the plurality of hydrophobic compounds of the hydrophobic material  130  upon reaction with the Ti atoms of the plurality of structures  104 . The reactive head group may be a phosphonate group or a phosphate group. The hydrophobic tail group of each of the plurality of precursor compounds may be the same as the hydrophobic tail group of each of the plurality of hydrophobic compounds of the hydrophobic material  130 . Each of the plurality of precursor compounds may be selected such that the plurality of precursor compounds do not substantially react with each other (e.g., cross-link) prior to attaching to the plurality of structures  104 . By way of non-limiting example, each of the plurality of precursor compounds may be an organo-phosphonic acid or an organo-phosphoric acid, respectively having the structure shown below: 
     
       
         
         
             
             
         
       
     
     where R is the hydrophobic tail group as previously described above. Non-limiting examples of compounds that may be utilized as the plurality of precursor compounds include mono(n-hexyl) phosphonic acid, mono(n-heptyl) phosphonic acid, mono(n-octyl) phosphonic acid, mono(n-nonyl) phosphonic acid, mono(n-decyl) phosphonic acid, mono(n-undecyl) phosphonic acid, mono(n-dodecyl) phosphonic acid, mono(n-tridecyl) phosphonic acid, mono(n-tetradecyl) phosphonic acid, mono(n-pentadecyl) phosphonic acid, mono(n-hexadecyl) phosphonic acid, mono(n-heptadecyl) phosphonic acid, mono(n-octadecyl) phosphonic acid, mono(2-ethylhexyl) phosphonic acid, mono(isodecyl) phosphonic acid, mono(olyel) phosphonic acid, mono(stearyl) phosphonic acid, or combinations thereof. In at least some embodiments, each of the plurality of precursor compounds is mono(n-octyl) phosphonic acid. 
     Accordingly, a method of forming a hydrophobic surface on a semiconductor device structure may comprise forming at least one structure having at least one exposed surface comprising titanium atoms. The at least one exposed surface of at least one structure may be contacted with at least one of an organo-phosphonic acid and an organo-phosphoric acid to form a material having a hydrophobic surface on the at least one exposed surface of the least one structure. 
     The plurality of structures  104  may be exposed to or treated with the plurality of precursor compounds until substantially all of the Ti atoms on the exposed surfaces of the plurality of structures  104  bond (e.g., through a monodentate interaction, such as covalent bonding) with at least a portion of the plurality of precursor compounds, or until access to remaining Ti atoms on the exposed surfaces of the plurality of structures  104  is substantially impeded or prevented. The plurality of precursor compounds may spontaneously adsorb to the plurality of structures  104 . The formation of the hydrophobic material  130  may terminate when Ti atoms are no longer available (i.e., unreacted with a precursor compound of the plurality of precursor compounds, and accessible for reaction with a precursor compound of the plurality of precursor compounds) on the exposed surfaces of the plurality of structures  104 . Accordingly, the formation of the hydrophobic material  130  on the exposed surfaces of the plurality of structures  104  may be self-assembled and self-limiting. 
     In one of more embodiments, a solution including the plurality of precursor compounds and at least one solvent may be used to contact the exposed surfaces of the plurality of structures  104  with the plurality of precursor compounds. The at least one solvent may be any solvent in which the plurality of precursor compounds is substantially soluble including, but not limited to, an organic solvent, such as an alcohol (e.g., ethanol, isopropanol, etc.). In at least some embodiments, the at least one solvent is isopropanol. The solution may include a concentration of the plurality of precursor compounds sufficient to impart the hydrophobic surface  132  of the hydrophobic material  130  with the contact angle previously described above (e.g., greater than or equal to about ninety degrees (90°)). In one or more embodiments, the concentration of the plurality of precursor compounds may facilitate bonding with at least a majority of the Ti atoms on the exposed surfaces of the plurality of structures  104 . The concentration of the plurality of precursor compounds in the solution may be tailored to the surface area and the surface chemistry (e.g., Ti atom content) of at least the plurality of structures  104 . The solution may include an excess of the plurality of precursor compounds relative to the number of available Ti atoms on the exposed surfaces of the plurality of structures  104 . As a non-limiting example, the concentration of the plurality of precursor compounds in the solution may be within a range of from about 1 milliMolar (mM) to about 10 mM. In at least some embodiments, the semiconductor device structure  100  may be exposed to a 1 mM solution of mono(n-octyl) phosphonic acid in isopropanol. 
     The semiconductor device structure  100  may be exposed to the solution by conventional techniques including, but not limited to, spin coating, spray coating, dip coating, immersion, soaking, or steeping. In at least some embodiments, the semiconductor device structure  100  is immersed in the solution at a sufficient temperature and for a sufficient period of time to facilitate self-assembly of the hydrophobic material  130  in a manner consistent with that described above. By way of non-limiting example, the semiconductor device structure  100  may be immersed in the solution at a temperature within a range of from about ambient temperature (e.g., from about 20° C. to about 25° C.) to just below the boiling point of the at least one solvent of the solution (e.g., below about 82.5° C. if the at least one solvent is isopropanol, such as about 80° C.), for a period of time within a range of from about 30 seconds to about 5 hours, such as from about 1 minute to about 2 hours, or from about 2 minutes to about 1 hour, or from about 2 minutes to about 20 minutes. An increase in the temperature may facilitate a decrease in the period of time the semiconductor device structure  100  is immersed. In at least some embodiments, the semiconductor device structure  100  may be immersed in a 1 mM solution of mono(n-octyl) phosphonic acid in isopropanol at a temperature of about 50° C. for about 10 minutes. 
     In additional embodiments, the semiconductor device structure  100  may be exposed to a gas or vapor including the plurality of precursor compounds. As a non-limiting example, the plurality of precursor compounds may be dissolved in the at least one solvent (e.g., isopropanol) to from the solution, the solution may be heated to above the boiling point of the at least one solvent (e.g., above 82.5° C. if the at least one solvent is isopropanol) to form a vapor including the plurality of precursor compounds, and the semiconductor device structure  100  may be exposed to the vapor (e.g., in a suitable containment vessel, such as a sealed pressure vessel) for sufficient period of time to facilitate self-assembly of the hydrophobic material  130  in a manner consistent with that described above. 
     The hydrophobic surfaces  132  of the hydrophobic material  130  may have a lower surface energy than the surfaces (e.g., the outer sidewall surfaces  122 , and the inner sidewall surfaces  116 ) of the plurality of structures  104 . The lower surface energy of the hydrophobic surfaces  132  may substantially limit or even prevent toppling or collapse of the plurality of structures  104 . Without being bound by theory, it is believed that the hydrophobic surfaces  132  of the hydrophobic material  130  may reduce the adhesion forces between surfaces within the capillaries  128  and a liquid, such as water, within the capillaries  128 . In addition, the lower surface energy of the hydrophobic surfaces  132  may substantially limit or even prevent stiction between the adjacent structures of the plurality of structures  104  in the event that the adjacent structures (including materials thereon, such as the hydrophobic material  130 ) come into contact. Without being bound by theory, it is believed that the hydrophobic material  130  reduces adhesion forces between contacting surfaces. Accordingly, by modifying the structures  104  to increase their hydrophobicity, the hydrophobic material  130  may substantially reduce or even eliminate adhesion-related damage to the semiconductor device structure  100 . 
     Referring to  FIG. 1C , following the formation of the hydrophobic material  130 , the semiconductor device structure  100  may be rinsed (e.g., with isopropanol, water, etc.), dried (e.g., blow dried with an inert gas, such as nitrogen gas; spin dried; dried with conventional supercritical carbon dioxide methods; etc.), and the hydrophobic material  130  ( FIG. 1B ) may be removed. Any process which does not result in stiction of adjacent structures of the plurality of structures  104  may be used to remove the hydrophobic material  130 . The hydrophobic material  130  may be, for example, removed by at least one of annealing (e.g., thermally annealing, reactively annealing, etc.) the semiconductor device structure  100  and exposing the semiconductor device structure  100  to one or more of high energy radiation (e.g., ultraviolet radiation), ozone, plasma, reactive ions, and an oxidizing agent. By way of non-limiting example, the semiconductor device structure  100  may be exposed to a temperature greater than or equal to a desorption temperature of the hydrophobic material  130 , such as greater than or equal to about 150° C., such as from about 200° C. to about 400° C. 
     Referring to  FIG. 1D , following the removal of the hydrophobic material  130 , the semiconductor device structure  100  may be subjected to additional processing. By way of non-limiting example, as shown in  FIG. 1D , a dielectric material  134  may be formed over and in contact with exposed surfaces of the semiconductor device structure  100  (e.g., exposed surfaces of each of the substrate  102 , the retaining structure  106 , and the plurality of structures  104 ), and a conductive material  136  may be formed over and in contact with the dielectric material  134 . The dielectric material  134  may substantially conform to the exposed surfaces of the semiconductor device structure  100 , and the conductive material  136  may fill remaining space within the openings  120  ( FIG. 1C ) and the capillaries  128  ( FIG. 1C ). The dielectric material  134  may be formed of and include at least one electrically insulative material including, but not limited to, an electrically insulative oxide, and an electrically insulative nitride. The conductive material  136  may formed of and include at least one electrically conductive material including, but not limited to, a metal (e.g., platinum, titanium, tungsten, ruthenium, etc.), a metal-containing composition (e.g., a metal nitride, a metal silicide, etc.), and a conductively doped semiconductor material (e.g., conductively doped silicon, conductively doped germanium, etc.). The dielectric material  134  and the conductive material  136  may be formed using conventional techniques, such as a physical vapor deposition (“PVD”) technique, a chemical vapor deposition (“CVD”) technique, or an atomic layer deposition (“ALD”) technique. PVD includes, but is not limited to, sputtering, evaporation, or ionized PVD. Such deposition techniques are known in the art and, therefore, are not described in detail herein. 
     In one or more embodiments, the degradation temperature of the hydrophobic material  130  may be less than or equal to a temperature used to form the dielectric material  134  over and in contact with the exposed surfaces of the semiconductor device structure  100 . Accordingly, in such embodiments, the removal of the hydrophobic material  130  and the formation of the dielectric material  134  may be performed in a single reaction chamber without breaking vacuum to the reaction chamber. The removal of the hydrophobic material  130  and the formation of the dielectric material  134  may be performed in a single processing act, such that the hydrophobic material  130  is volatilized and removed substantially simultaneously with the formation of the dielectric material  134 . In yet additional embodiments, the removal of the hydrophobic material  130  may be omitted, and the dielectric material  134  may be formed over and in contact with the hydrophobic material  130 . 
     With continued reference to  FIG. 1D , the conductive material  136 , dielectric material  134 , and the plurality of structures  104  ( FIG. 1C ) form a plurality of capacitors  138 . The conductive material  136  may be considered to form a capacitor plate extending across the plurality of capacitors  138 . The plurality of capacitors  138  may be electrically coupled to a plurality of bitlines (not shown) through a plurality of transistor gates (not shown). The bitlines and the transistor gates may be conventionally formed at an appropriate processing stage. The transistor gates may be coupled to a plurality of wordlines (not shown). The combination of the wordlines and the bitlines may facilitate addressing of dynamic random access memory (DRAM) cells including the plurality of capacitors  138 . The plurality of capacitors  138  may, therefore, be incorporated into a DRAM array. 
     As previously described above, the method of the disclosure may be applicable to structures beyond those depicted in  FIGS. 1A-1D . By way of non-limiting example and referring to  FIG. 2A , the above process may be used to form hydrophobic material  230  having a hydrophobic surface  232  over and in contact with at least surfaces of a plurality of structures  204  of a semiconductor device structure  200 . As shown in  FIG. 2A , each of the plurality of structures  204  may have a stud-type shape. Each of the plurality of structures  204  may have a diameter D 2  and a height H 2  substantially similar to the diameter D 1  and the height H 1  described above in reference to  FIG. 1A , or at least one of the diameter D 2  and the height H 2  of each of the plurality of structures  204  may be substantially different than the diameter D 1  and the height H 1  described above with reference to  FIG. 1A . In addition, a distance S 2  between adjacent structures of the plurality of structures  204  may be substantially similar to the distance S 1  described above in reference to  FIG. 1A , or the distance S 2  between at least one structure of the plurality of structures  204  and at least one other structure of the plurality of structures  204  may be substantially different than the distance S 1  described above with reference to  FIG. 1A . Each of the plurality of structures  204  may be formed of and include a titanium-containing material (e.g., Ti, TiN, TiC, TiSi, TiSi 2 , TiO, TiO 2 , a Ti alloy, etc.). Furthermore, the formation of the hydrophobic material  230  over and in contact with the plurality of structures  204 , and subsequent processing of the plurality of structures  204  may be substantially similar to that described above with reference to  FIGS. 1B through 1D , resulting in a plurality of capacitors  238  including a dielectric material  234 , a conductive material  236 , and the plurality of structures  204 , as depicted in  FIG. 2B . 
     In additional embodiments, the method of the disclosure may be used to form a hydrophobic material on a substantially planar structure including Ti. In yet additional embodiments, the method of the disclosure may be used to form a hydrophobic material on a titanium material coating at least one structure (e.g., a titanium material coating a structure having one of a rectangular column shape, a cylindrical column shape, a dome shape, a pyramid shape, a frusto-pyramidal shape, a cone shape, a frusto-conical shape, a fin shape, a pillar shape, a container shape, a stud shape, a circular shape, an ovular shape, a quadrilateral shape, and an irregular shape). 
     The properties of the hydrophobic material  130 ,  230  of the disclosure may substantially alleviate adhesion problems (e.g., toppling, collapse, and stiction, such as release-related stiction and in-use stiction) related to the formation of the plurality of capacitors  138 ,  238 . The hydrophobic material  130 ,  230  exhibits low surface energy, a low coefficient of friction, and high wear resistance. In addition, the hydrophobic material  130 ,  230  is chemically inert. In some embodiments, hydrophobic material  130 ,  230  enables beading of the aqueous solution from the hydrophobic surfaces  132 ,  232  and/or changes a meniscus of aqueous solution within capillaries  128 ,  228  from concave to convex. In some embodiments, some stiction may occur in spite of hydrophobic material  130 ,  230 , but the hydrophobic material  130 ,  230  can advantageously provide insulation between adjacent structures (e.g., to substantially avoid electrical shorting). The hydrophobic material  130 ,  230  may substantially improve a yield of undamaged structures  104 ,  204  for the semiconductor device structure  100 ,  200  relative to conventional methods of forming the semiconductor device structure  100 ,  200 . The methods of the disclosure advantageously enable the formation of semiconductor device structures (e.g., DRAM structures, NAND structures, MEMS structures, etc.) memory cells, and semiconductor devices that exhibit increased reliability, performance, and durability. 
     The following examples serve to explain embodiments of the disclosure in more detail. The examples are not to be construed as being exhaustive or exclusive as to the scope of the disclosure. 
     EXAMPLES 
     Example 1 
     X-Ray Photoelectron Spectroscopy (XPS) Surface Analysis 
     Three coupon samples were prepared by treating substrate stacks including TiN (72 Å), Ti (100 Å), and an oxide (1 kÅ) with a 1 mM solution of mono(n-octyl) phosphonic acid in isopropanol under a variety of conditions. A film was formed on the TiN surfaces of each of the coupon samples. The three coupon samples and one control sample were subjected to XPS analysis. The control sample was a substrate stack as described above that was not treated with the 1 mM solution of mono(n-octyl) phosphonic acid in isopropanol. As shown in  FIG. 3 , XPS survey spectra of the six coupon samples detected the presence of C, N, O, P, Ti, and trace F and Si at the surface tested (i.e., the surface including the film). High resolution XPS spectra of C1s, N1s, O1s, P2p, and Ti3s were acquired at 30 degree take-off angle (TOA) for quantification. The surface elemental concentrations in atom % for the six coupon samples and the control sample are shown below in Table 1, along with the atomic ratios of C/Ti. The XPS analysis results indicate the mono(n-octyl) phosphonic acid of the solution bonded to the TiN surfaces of the each of the substrate stacks. The XPS analysis results illustrate the reproducibility of the method of the disclosure. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 XPS Analysis Data 
               
            
           
           
               
               
               
            
               
                   
                 Elemental Concentrations 
                   
               
               
                   
                 (atomic %) at 30° TOA 
                 Atomic 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Sample 
                 C 
                 N 
                 O 
                 P 
                 Ti 
                 Ratio C/Ti 
               
               
                   
               
               
                 Control 
                 12.6 
                 37.1 
                 15.2 
                 ND 
                 35.1 
                 0.36 
               
               
                 S1 
                 35.2 
                 19.9 
                 20.2 
                 1.7 
                 23.0 
                 1.53 
               
               
                 S2 
                 38.4 
                 17.6 
                 19.8 
                 2.7 
                 21.5 
                 1.79 
               
               
                 S3 
                 38.8 
                 18.6 
                 19.6 
                 1.7 
                 21.4 
                 1.82 
               
               
                   
               
            
           
         
       
     
     Example 2 
     TOF-SIMS Analysis 
     Three coupon samples were prepared by treating substrate stacks including TiN (72 Å), Ti (100 Å), and an oxide (1 kÅ) with a 1 mM solution of mono(n-octyl) phosphonic acid in isopropanol under a variety of conditions. A film was formed on the TiN surfaces of each of the coupon samples. The three coupon samples and one control sample were subjected to TOF-SIMS analysis using an IonTOF TOFSIMS 5 instrument, equipped with a hot/cold variable temperature stage using 25 KeV Bi 1   +  primary analysis ions. The control sample was a substrate stack as described above that was not treated with the 1 mM solution of mono(n-octyl) phosphonic acid in isopropanol. 
       FIGS. 4A and 4B  depict positive mode ( FIG. 4A ) and negative mode ( FIG. 4B ) survey mass spectra from each coupon sample and the control sample integrated over the entire temperature desorption profile. From these spectra and knowledge of the molecular structure of mono(n-octyl) phosphonic acid, several secondary ions of interest were selected.  FIGS. 5A and 5B  depict the thermal desorption profiles for selected positive ions ( FIG. 5A ) and selected negative ions ( FIG. 5B ) for the control sample.  FIGS. 6A and 6B  depict the thermal desorption profiles for selected positive ions ( FIG. 6A ) and selected negative ions ( FIG. 6B ) for coupon sample 1.  FIGS. 7A and 7B  depict the thermal desorption profiles for selected positive ions ( FIG. 7A ) and selected negative ions ( FIG. 7B ) for coupon sample 2.  FIGS. 8A and 8B  depict the thermal desorption profiles for selected positive ions ( FIG. 8A ) and selected negative ions ( FIG. 8B ) for coupon sample 3.  FIG. 9A  depicts a C 2 H 3  thermal desorption overlay for the three coupon samples (i.e., coupon samples 1, 2, and 3) and the control sample.  FIG. 9B  depicts a PO 2   −  thermal desorption overlay for the three coupon samples and the control sample. 
     The results of the TOF-SIMS indicate the film of each coupon sample was a monolayer or less in thickness, primarily due to the relative intensities of the Ti and organic fragment secondary ions. Aliphatic organic fragment ions are higher than those resulting from contamination of the control sample. The control sample was freshly prepared, while the coupon samples accumulated contamination for several weeks prior to analysis. The presence of mono(n-octyl) phosphonic acid cross-linked to the TiN surface is indicated by the presence of the PO 2   −  and PO 3   −  secondary ions. The intensity of the phosphate ions is not believed to indicate a linear relationship with coverage in the thermal profile. Namely, the phosphate head group of the mono(n-octyl) phosphonic acid is believed to react with the TiN surface, and cross-linked mono(n-octyl) phosphonic acid may be thermally degraded at the temperatures studied, with the organic portion of the cross-linked mono(n-octyl) phosphonic acid being more thermally labile than the mono(n-octyl) phosphonic acid as a whole. This is suggested by the overlay profiles shown in  FIGS. 9A and 9B , wherein C 2 H 3   +  intensity decreases with increasing temperature ( FIG. 9A ), while PO 2   −  intensity increases with increasing temperature ( FIG. 9B ). 
     Example 3 
     Contact Angle Testing 
     The contact angle of a surface of a substrate stack before and after treatment with mono(n-octyl) phosphonic acid was tested. The substrate stack included TiN (72 Å), Ti (100 Å), and an oxide (1 kÅ). As depicted in  FIG. 10A , the surface of the TiN exhibited a contact angle about fifty-five degrees (55°) prior to cleaning. The surface of the TiN was cleaned by exposure to aqueous hydrofluoric acid (100:1) for two minutes, followed by exposure to tetramethylammonium hydroxide (TMAH) at 80° C. for six minutes, followed by exposure to aqueous hydrofluoric acid (100:1) for one minute. As depicted in  FIG. 10B , the cleaned surface of the TiN exhibited a contact angle about thirty degrees (30°). The substrate stack was then immersed in a 1 mM solution of mono(n-octyl) phosphonic acid in isopropanol at 50° C. for 10 minutes, forming a film on the cleaned surface of the TiN. As depicted in  FIG. 10C , the surface of the film exhibited a contact angle about one-hundred and twenty degrees (120°), indicating that a hydrophobic surface was formed on the TiN. 
     Example 4 
     Comparative Analysis of Structural Integrity 
     A first structure including a plurality of container-shaped TiN structures processed using conventional techniques was compared to a second structure including a plurality of container-shaped TiN structures processed according to the methods of the disclosure. Each of the plurality of container-shaped TiN structures of the first structure and each of the plurality of container-shaped TiN structures of the second structure were cylindrical in shape, and exhibited an length of approximately 15 kÅ, a diameter of approximately 400 Å, and a sidewall thickness of approximately 65 Å.  FIG. 11  is a scanning electron micrograph (SEM) showing a partial top-down view of an as-fabricated structure including such a plurality of container-shaped TiN structures (i.e., prior to conventional processing or processing according to the methods of the disclosure). 
     The plurality of container-shaped TiN structures of the first structure were processed using the following sequence: exposure to aqueous hydrofluoric acid (100:1) for two minutes, exposure to TMAH at 80° C. for three minutes, exposure to aqueous hydrofluoric acid (100:1) for one minute at room temperature (about 20° C.), rinsing with deionized water at room temperature, rinsing with isopropanol at room temperature, and blow drying at room temperature using gaseous nitrogen (N 2 ).  FIGS. 12A and 12B  are SEMs taken at different locations along the first structure following the aforementioned processing sequence. As shown in  FIGS. 12A and 12B , the plurality of container-shaped TiN structures of the first structure exhibited significant toppling and collapse. 
     The plurality of container-shaped TiN structures of the second structure, which included a hydrophobic material formed from mono(n-octyl) phosphonic acid, were processed using the following sequence: exposure to aqueous hydrofluoric acid (100:1) for two minutes, exposure to TMAH at 80° C. for three minutes, exposure to aqueous hydrofluoric acid (100:1) for one minute at room temperature, rinsing with deionized water at room temperature, immersion in a 1 mM solution of mono(n-octyl) phosphonic acid in isopropanol at 50° C. for 10 minutes, rinsing with isopropanol at room temperature, and blow drying at room temperature using gaseous nitrogen (N 2 ).  FIGS. 13A and 13B  are SEMs taken at different locations along the second structure following the aforementioned processing sequence. As shown in  FIGS. 13A and 13B , the plurality of container-shaped TiN structures of the second structure exhibited substantially reduced toppling and collapse as compared to the first structure. 
     While the disclosure is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, the disclosure is not intended to be limited to the particular forms disclosed. Rather, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure as defined by the following appended claims and their legal equivalents.