Patent Publication Number: US-2023140344-A1

Title: Trimmable Semiconductor-Based Capacitor

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application claims filing benefit of U.S. Provisional patent application Ser. No. 63/274,567 having a filing date of Nov. 2, 2021, which is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The subject matter of the present invention relates generally to a semiconductor-based capacitor assembly having selectively tunable capacitance values. 
     BACKGROUND 
     Semiconductor-based capacitors can provide a variety of benefits, such as temperature stability, generally high breakdown voltages, and low leakage currents. Thus, semiconductor-based capacitors may be desirable for use in a wide variety of applications, particularly those applications in which reliability when subjected to substantial mechanical and/or environmental stress is desired or necessary. However, some applications in which semiconductor-based capacitors may be desirable can require precision tunable capacitance of the capacitor. For instance, it may be desirable to finely tune the capacitance after the capacitor assembly is installed in a circuit. 
     Consequently, there is a need for a semiconductor-based capacitor that can offer more variety to enable formation of dynamic capacitor arrays within a limited area. In particular, a semiconductor-based capacitor assembly that is finely tunable in a circuit may be useful. 
     SUMMARY 
     Objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention. 
     The present invention is directed to a capacitor assembly. The capacitor assembly includes: a substrate comprising a semiconductor material; a primary oxide layer formed on a surface of the substrate; a secondary oxide layer formed on a surface of the substrate; a primary conductive layer formed over at least a portion of the primary oxide layer; a secondary conductive layer formed over at least a portion of the secondary oxide layer; a first terminal connected with the primary conductive layer; and a conduction line formed over the substrate. The conduction line is connected between the primary conductive layer and the secondary conductive layer. The capacitor assembly has a capacitance value in a range from a minimum capacitance value to a maximum capacitance value. 
     In one particular embodiment, the primary oxide layer can be spaced apart from the secondary oxide layer. 
     In another embodiment, the secondary conductive layer can include a plurality of discrete conductive regions, wherein each of the plurality of discrete conductive regions are spaced apart from one another. Further, the conduction line can include a plurality of discrete conduction lines connecting each of the plurality of discrete conductive regions to the primary conductive layer. 
     In an additional embodiment, the conduction line can be formed from a thin layer of metal. 
     In yet another embodiment, the conduction line can include a first end connected to the primary conductive layer and a second end connected to the secondary conductive layer, wherein the conduction line is configured to be severed between the first end and the second end, further wherein severing the conduction line reduces a capacitance value of the capacitor assembly to less than the maximum capacitance value. 
     In a further embodiment, the minimum capacitance value can be defined by the primary conductive layer. 
     In still another embodiment, the maximum capacitance value can be defined by both the primary conductive layer and the secondary conductive layer. 
     In an additional embodiment, the capacitance value of the capacitor assembly can be adjusted between the minimum capacitance value and the maximum capacitance value in increments of about 0.05 pF. 
     In another embodiment, the primary oxide layer and the secondary oxide layer can be coplanar. Further, the primary conductive layer and the secondary conductive layer can be coplanar. 
     In a further embodiment, the capacitor assembly can further include an insulator layer formed over the primary oxide layer and/or the secondary oxide layer. Moreover, the insulator layer can be formed between the primary oxide layer and the primary conductive layer and/or between the secondary oxide layer and the secondary conductive layer. 
     In an additional embodiment, the semiconductor material of the substrate can include silicon. 
     In one more embodiment, the primary oxide layer can include silicon oxide and the secondary oxide layer can include silicon oxide. 
     The present invention is further directed to a method of forming a trimmable capacitor assembly. The method includes steps of: forming a primary oxide layer on a surface of a substrate comprising a semiconductor material; forming a secondary oxide layer on a surface of the substrate, wherein the secondary oxide layer is spaced from the primary oxide layer; depositing a primary conductive layer over at least a portion of the primary oxide layer; depositing a secondary conductive layer over at least a portion of the secondary oxide layer; depositing a first terminal on the first conductive layer; and depositing a conduction line over the substrate, wherein the conduction line connects between the primary conductive layer and the secondary conductive layer. 
     In one particular embodiment, the method can further include a step of trimming the conduction line at a point between the primary conductive layer and the secondary conductive layer to sever the connection between the primary conductive layer and the secondary conductive layer. Further, the step of trimming the conduction line can reduce a capacitance value of the capacitor assembly. Moreover, the method can further include a step of coupling the trimmable capacitor assembly to a substrate form an integrated circuit, wherein the step of trimming the conduction line can be performed after formation of the integrated circuit. 
     In another embodiment, the steps of depositing the primary conductive layer and the secondary conductive layer can include depositing a conductive material over the primary oxide layer and the secondary oxide layer and etching the conductive material to form the primary conductive layer and the secondary conductive layer, wherein the primary conductive layer and the secondary conductive layer can be spaced apart. 
     These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: 
         FIG.  1    illustrates a top view of a capacitor assembly according to one particular embodiment of the present invention; 
         FIG.  2    illustrates a top view of another embodiment of a capacitor assembly according to one particular embodiment of the present invention; and 
         FIG.  3    illustrates a side cutaway view of the capacitor assembly of  FIG.  1    taken parallel to an X-direction. 
     
    
    
     DETAILED DESCRIPTION 
     Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
     As used herein, the terms “about,” “approximately,” or “generally,” when used to modify a value, indicates that the value can be raised or lowered by 5% and remain within the disclosed embodiment. Further, when a plurality of ranges are provided, any combination of a minimum value and a maximum value described in the plurality of ranges are contemplated by the present invention. For example, if ranges of “from about 20% to about 80%” and “from about 30% to about 70%” are described, a range of “from about 20% to about 70%” or a range of “from about 30% to about 80%” are also contemplated by the present invention. 
     Generally speaking, the present invention is directed to a capacitor assembly including a primary capacitor and a secondary capacitor formed on a substrate. The primary capacitor and the secondary capacitor can be connected by a conduction line. The conduction line can be formed from a thin metal connection. The conduction line can be severed, i.e., trimmed, to finely tune a capacitance value of the capacitor assembly. The present inventor has found that the capacitor assembly of the present invention can allow for tighter tolerance and wider variance of the capacitance value of the capacitor assembly. Further, the present inventor has found that the capacitor assembly can be trimmed after installing the capacitor assembly in the circuit, thereby enabling fine tuning of the capacitance value of the capacitor assembly for applications requiring precision tunable capacitance. As examples, the capacitance value of the capacitor assembly of the present invention can be tunable in increments as small as about 0.05 pF. 
     The MOS capacitor assembly can include a substrate including a semiconductor material, such as silicon, gallium arsenide, germanium, silicon carbide, strontium titanate, and/or mixtures thereof. The substrate can be doped with one or more suitable dopants, such as boron, arsenic, phosphorus, gallium, aluminum, indium, and antimony. 
     The surface of the substrate can generally be smooth. For example, the surface of the substrate can be free of pores, trenches, or the like. The oxide layer can have a generally uniform thickness on the surface of the oxide layer. For example, the thickness of the oxide layer can vary less than 20% across the oxide layer, in some embodiments less than 10%, and in some embodiments less than 5%. As used herein, the term “generally,” e.g., “generally smooth” or “generally equal”, does not necessarily mean that a characteristic is exactly or perfectly smooth or equal, and may allow a small difference if the respective layers are uniformly connected to adjacent layers within the capacitor assembly and/or when mounted to a substrate such as a circuit board. 
     As used herein, a first layer that is “formed over” a second layer may refer to the first layer being arranged over the second layer with respect to a thickness direction (i.e., the z-direction) of the monolithic substrate. The first layer may be directly in contact with the second layer. However, intermediate layers may also be formed therebetween such that the first layer and second layer do not directly contact each other. 
     The capacitor assembly can include an oxide layer formed on a surface of the substrate. The oxide layer can be or include silicon oxide and/or oxides of other example semiconductor materials described herein. The oxide layer can be grown in situ on the substrate. Lithography (e.g., photolithography) techniques can be used to define the shape of the oxide layer. For instance, portions of the oxide layer can be removed through etching such that the oxide layer is shaped as desired. 
     In some aspects of the invention, the capacitor assembly can include a primary oxide region and a secondary oxide region spaced apart from the primary oxide region. For instance, the oxide layer can be formed on the surface of the substrate, and the shapes of the primary oxide region and the secondary oxide region can be formed, e.g., by lithography techniques, after the oxide layer is formed. However, any suitable methods by which the primary oxide region and the secondary oxide region can be formed on the substrate are contemplated by the present invention. 
     One or more protective layers can be formed over the surface of the substrate. The terminals can be exposed through the protective layers for electrical connection when surface mounting the capacitor. Examples materials for the protective layer include benzocyclobutene (BCB), polyimide, silicon oxynitride, Al2O3, SiO2, Si3N4, epoxy, glass, or another suitable material. 
     For instance, the one or more protective layers can include an insulator layer formed over at least a portion of the oxide layer. The insulator layer can be or include silicon nitride and/or other electrically insulating materials described herein, including but not limited to silicon oxynitride (SiON). The insulator layer(s) can be formed over a first portion of the oxide layer that is distinct from a second portion of the oxide layer that is free of the insulator layer(s). Lithography (e.g., photolithography) techniques can be used to define the shape of the insulator layer, if desired. For instance, portions of the insulator layer can be removed through etching such that the insulator layer is shaped as desired and to expose at least a portion of the oxide layer below the insulator layer. 
     By providing an insulator layer formed over the oxide layer, the reliability of a capacitor can be improved. Specifically, any potential defects, e.g., pores, in the oxide layer and/or in the insulator layer are unlikely to be aligned in the Z-direction. For instance, the insulator layer may cover or fill in any defects, holes or imperfections in the surface of the oxide layer. As a result, forming the insulator layer over at least a portion of the oxide layer can reduce the likelihood that the capacitor will short-circuit. Thus, as described above, the capacitance value of the capacitor can be increased by providing the insulator layer formed over the oxide layer. For instance, the capacitance value may be increased by up to one and a half times when the insulator is formed over the oxide layer. 
     In some aspects of the present invention, the insulator layer can include a primary insulator region and a secondary insulator region spaced from the primary insulator region. The primary insulator region can be formed within a perimeter of the primary oxide region. The secondary insulator region can be formed within a perimeter of the secondary oxide region. The primary insulator region and/or secondary insulator region can be formed over any portion of the primary oxide layer or secondary oxide layer, respectively. For instance, in some aspects of the present invention, the capacitor assembly may include a primary insulator region formed over the primary oxide region, while there may be no secondary insulator region present over the secondary insulator region, or vice versa. 
     The capacitor assembly can include a conductive layer formed over at least a portion of the oxide layer. The conductive layer can be contained within a perimeter of the oxide layer. The conductive layer can be free of direct contact and/or direct electrical connection with the substrate. The conductive layer can be or include metal, such as aluminum, copper, gold, silver, nickel, or mixtures thereof. 
     The conductive layer can include a primary conductive region and a secondary conductive region. The primary conductive region can be formed over the primary oxide region. The secondary conductive region can be formed over the secondary oxide region. The secondary conductive region can be spaced apart from the primary conductive region such that the primary conductive region and the secondary conductive region are not directly in contact with each other. In other words, the material of the primary conductive region does not touch the material of the secondary conductive region, and at least a portion of the surface of the substrate and/or the oxide layer can be exposed between the primary conductive region and the secondary conductive region. 
     The capacitor assembly can include a conduction line connected between the primary conductive region and the secondary conductive region. The conduction line can be formed from a thin line of metal, e.g., aluminum or any other suitable conductive material. The conduction line can be configured to be trimmed, i.e., the connection between the primary conductive region and the secondary conductive region severed. For instance, the conduction line can be trimmed by a laser or any other suitable means. 
     In some aspects of the present invention, the secondary conductive region can comprise a plurality of discrete secondary conductive regions spaced apart from one another. In such an arrangement, the capacitor assembly can include a discrete conduction line connected between each of the plurality of discrete secondary conductive regions and the primary conductive region. 
     The capacitor assembly of the present invention can be formed as a thin-film capacitor assembly, i.e., having one or more thin-film layers. For instance, the conductive layer, the oxide layer, and the insulator layer can each be formed as a thin-film layer, respectively. The thin-film components may be formed of a variety of suitable materials. The thin-film capacitor may include one or more conductive layers. The conductive layer(s) may include a variety of suitable conductive materials. Example conductive materials include copper, nickel, gold, tin, lead, palladium, silver, and alloys thereof. Any conductive metallic or non-metallic material that is suitable for thin-film fabrication may be used, however. 
     Various thin-film techniques can be used to form thin-film layers, such as the conductive layer, insulator layer(s), terminals, or the like. Examples of such techniques that may be employed include chemical deposition (e.g., chemical vapor deposition), physical deposition (e.g., sputtering), or any other suitable deposition technique for forming thin-film elements. Additional examples include any suitable patterning technique (e.g., photolithography), etching, and any other suitable subtractive technique for forming thin-film elements. 
     The thin-film layers can have a range of thicknesses. For example, the thin-film layers can have thicknesses that can range from about 0.0375 micrometers (microns) to about 40 microns, in some embodiments from about 0.1 microns to about 30 microns, in some embodiments from about 0.2 microns to about 20 microns in some embodiments from about 0.4 microns to about 10 microns. 
     The thin-film components may be precisely formed using a variety of suitable subtractive, semi-additive, or fully additive processes. For example, physical vapor deposition and/or chemical deposition may be used. For instance, in some embodiments, the thin-film components may be formed using sputtering, a type of physical vapor deposition. A variety of other suitable processes may be used, however, including plasma-enhanced chemical vapor deposition (PECVD), electroless plating, and electroplating, for example. Lithography masks and etching may be used to produce the desired shape of the thin-film components. A variety of suitable etching techniques may be used including dry etching using a plasma of a reactive or non-reactive gas (e.g., argon, nitrogen, oxygen, chlorine, boron trichloride) and/or wet etching. 
     The capacitor assembly can include a first terminal connected with the conductive layer. For instance, the first terminal can be connected with the first conductive region. As used herein “connected with” can refer to components that are in directly physically contact. “Connected with” can also refer to items that are physically connected by one or intermediate conductive layers such that the items are in direct electrically connection (e.g., without a resistive layer or dielectric layer therebetween). The first terminal can be formed over the conductive layer, e.g., formed over the first conductive region. For instance, the first terminal can be coupled to the conductive layer, e.g., directly contacting with the conductive layer. The first terminal can be contained within a perimeter of the conductive layer, e.g., within a perimeter of the first conductive region. 
     In some aspects of the present invention, only the first conductive region is configured for coupling with the first terminal. For instance, the secondary conductive region may not be configured for coupling with a terminal such as a wire bondable terminal. 
     The capacitor assembly can have a second terminal connected with a surface of the substrate, e.g., a surface of the substrate opposite the surface of the substrate upon which the oxide layer is formed in the Z-direction. The second terminal can connect to a ground or act as a ground on the backside of the substrate. The first terminal can be spaced apart from the second terminal of the substrate in a Z-direction. The second terminal can be formed by a bare surface of the substrate. Additionally or alternatively, the second terminal can include a second conductive layer formed over a surface of the substrate opposite the surface of the substrate upon which the oxide layer is formed in the Z-direction. 
     A capacitor can be formed between the first terminal and the second terminal. The capacitor can have a minimum capacitance value and a maximum capacitance value. The minimum capacitance value can be defined by the area of the primary oxide region and primary conductive region coupled between the first terminal and the second terminal. The maximum capacitance value can be defined by the cumulative capacitance value of the primary oxide region and primary conductive region coupled between the first terminal and the second terminal, and the capacitance value of the capacitive elements formed by the secondary conductive region, the secondary oxide region and the substrate, when each conduction line remains intact. Depending on the area of the capacitor chip, as described above, as well as additional factors including the dielectric constant and properties of the materials used to form the capacitor, the capacitor assembly can maintain a capacitance value in a range between about 0.1 pF and about 1800 pF, such as from about 1 pF to about 1500 pF, for instance from about 10 pF to about 1000 pF. 
     The trimmable capacitor assembly of the present invention can have a precisely tunable capacitance value between the minimum capacitance value and the maximum capacitance value. For instance, one or more conduction lines between one or more of the discrete secondary conductive regions and the primary conductive region can be selectively trimmed or severed in order to disconnect any electrical connection, thereby reducing the capacitance value of the capacitor assembly. In some aspects of the present invention, the capacitance value of the trimmable capacitor assembly can be tuned in increments as small as about 0.05 pF. The increments by which the capacitance value of the trimmable capacitor assembly can be tuned can be directly related to the area of each discrete secondary conductive region and the number of discrete secondary conductive regions present on the capacitor chip, i.e., substrate. 
     A method of forming the capacitor assembly can include steps of: forming a primary oxide layer on a surface of a substrate comprising a semiconductor material; forming a secondary oxide layer on a surface of the substrate, wherein the secondary oxide layer is spaced from the primary oxide layer; depositing a primary conductive layer over at least a portion of the primary oxide layer; depositing a secondary conductive layer over at least a portion of the secondary oxide layer; depositing a first terminal on the first conductive layer; and depositing a conduction line over the substrate, wherein the conduction line connects between the primary conductive layer and the secondary conductive layer. 
     The method can include a step of trimming the conduction line at a point between the primary conductive layer and the secondary conductive layer to sever the connection between the primary conductive layer and the secondary conductive layer. The step of trimming the conduction line can reduce a capacitance value of the capacitor assembly. 
     The method can include a step of coupling the trimmable capacitor assembly to a substrate form an integrated circuit. The step of trimming the conduction line can be performed after formation of the integrated circuit, e.g., after coupling the capacitor assembly to the substrate. 
     The steps of depositing the primary conductive layer and the secondary conductive layer can include depositing a conductive material over the primary oxide layer and the secondary oxide layer and etching the conductive material to form the primary conductive layer and the secondary conductive layer. The primary conductive layer and the secondary conductive layer can be spaced apart. 
     The specific features of the trimmable capacitor assembly of the present invention may be better understood with reference to  FIGS.  1 - 3   . 
       FIG.  1    is a top view of a capacitor assembly  100  according to aspects of the present disclosure. The capacitor assembly  100  can include a substrate  102  including a semiconductor material, such as silicon. The capacitor assembly  100  can include an oxide layer  104  formed on a surface  106  of the substrate  102 . The capacitor assembly  100  can include a conductive layer  108  formed over at least a portion of the oxide layer  104 . The conductive layer  108  can be contained within a perimeter  110  of the oxide layer  104 . The conductive layer  108  can be free of direct contact and/or direct electrical connection with the substrate  102 . 
     The substrate  102  can be a monolithic substrate that includes a surface  106  as described above. The surface  106  can be a top surface of the substrate  102 . The substrate  102  can include a first side and a second side which each extend parallel to an X-direction  10 . The substrate  102  can include a first edge and a second edge which each extend parallel to a Y-direction  20  perpendicular to the X-direction  10 . The top surface  106  can extend between the first side and the second side in the X-direction  10  and between the first edge and the second edge in the Y-direction  20 . The substrate  102  can further include a bottom surface, i.e., backside, that extends parallel to the top surface  106  in a vertical Z-direction  30 . The bottom surface can extend between the first side and the second side in the X-direction  10  and between the first edge and the second edge in the Y-direction  20 . 
     The oxide layer  104  can be formed exclusively on the top surface  106  of the substrate  102 . For instance, the oxide layer  104  can be formed within the perimeter of the surface  106 . The oxide layer  104  can extend over the entire top surface  106 , i.e., from the first side to the second side from the first edge to the second edge, or any portion thereof. For instance, the oxide layer  104  can include a primary oxide region  112  and a secondary oxide region  114 . The primary oxide region  112  and the secondary oxide region  114  can be spaced apart by a trimming region  116 . 
     A ratio of a length  150  of the substrate  102  to a length  152  of the primary oxide region  112  may be less than about 5, such as less than about 3, such as less than about 2. For instance, a ratio of a length  150  of the substrate  102  to a length  152  of the primary oxide region  112  can be in a range from about 1.25:1 to about 5:1. A ratio of a width  154  of the substrate  102  to a width  156  of the primary oxide region  112  may be less than about 5, such as less than about such as less than about 3, such as less than about 2. For instance, a ratio of a width  154  of the substrate  102  to a width  156  of the primary oxide region  112  can be in a range from about 1.25:1 to about 5:1. 
     A ratio of a length  150  of the substrate  102  to a length  158  of the secondary oxide region  114  may be less than about 5, such as less than about 3, such as less than about 2. For instance, a ratio of a length  150  of the substrate  102  to a length  158  of the secondary oxide region  114  can be in a range from about 1.25:1 to about 5:1. A ratio of a width  154  of the substrate  102  to a width  160  of the secondary oxide region  114  may be less than about 5, such as less than about such as less than about 3, such as less than about 2. For instance, a ratio of a width  154  of the substrate  102  to a width  160  of the secondary oxide region  114  can be in a range from about 1.25:1 to about 5:1. 
     The conductive layer  108  can include a primary conductive region  118  formed over the primary oxide region  112 . For instance, the primary conductive region  118  can be formed within a perimeter of the primary oxide region  112 . A primary capacitor can be formed between the primary conductive region  118  and the substrate  102 . The primary conductive region  118  can be free of direct contact and/or direct electrical connection with the substrate  102 . In this regard, the primary conductive region  118  can have the same, or generally similar, shape and size as the primary oxide layer  112 . For instance, a ratio of a length  150  of the substrate  102  to a length  162  of the primary conductive region  118  may be less than about 5, such as less than about 3, such as less than about 2. For instance, a ratio of a length  150  of the substrate  102  to a length  162  of the primary conductive region  112  can be in a range from about 1.25:1 to about 5:1. A ratio of a width  154  of the substrate  102  to a width  164  of the primary conductive region  118  may be less than about 5, such as less than about such as less than about 3, such as less than about 2. For instance, a ratio of a width  154  of the substrate  102  to a width  164  of the primary conductive region  118  can be in a range from about 1.25:1 to about 5:1. 
     A first terminal  140  can be connected with the conductive layer  108 . In particular, the first terminal  140  can be connected with the primary conductive region  118 . The first terminal  140  can be exposed along the surface  106  of the substrate  102 . For example, each of the first terminal  140  can be formed exclusively on the oxide layer  104 , e.g., exclusively on the primary oxide region  112 . The first terminal  140  can be configured for bonding to a substrate such as a circuit board, e.g., by wire bonding or any other suitable means. 
     The capacitor assembly  100  can include a second terminal  138  on the bottom surface  136  of the substrate  102 . The second terminal  130  can be formed by the bare material of the bottom surface  136  of the semiconductor substrate  102 . Additionally or alternatively, the second terminal  138  can be formed from a layer  142  of conductive material formed over the bottom surface  136  of the substrate  102  opposite the top surface  106  in the Z-direction. The second terminal  138  can connect to a ground or act as a ground on the backside of the substrate  102 . 
     Turning again to the conductive layer  108 , the conductive layer  108  can also include a secondary conductive region  120 . The secondary conductive region  120  can be formed over the secondary oxide region  114 , e.g., within a perimeter of the secondary oxide region  114 . The secondary conductive region  120  can be free of direct contact and/or direct electrical connection with the substrate  102 . 
     A conduction line  122  can be provided between the primary conductive region  118  and the secondary conductive region  120 . The conduction line can be formed from a thin layer of conductive material, e.g., metal, such as aluminum or any other suitable material. The conduction line  122  can form an electrical connection between the first conductive region  118  and the second conductive region  120 . The conduction line  122  can have a length  128  extending from a first end  124  of the conduction line  122  connected with the primary conductive region  118  to a second end  126  of the conduction line  122  connected with the secondary conductive region  120 . The conduction line  122  can have a width  130  extending perpendicular to the length  128 . As described above, the conduction line  122  can be trimmed, e.g., laser trimmed, to sever the connection between the primary conductive region  118  and the secondary conductive region  120  along the conduction line  122 . 
     The secondary conductive region  120  can include a plurality of discrete conductive regions  132 . Each of the discrete conductive regions  132  can be formed within the secondary conductive region  120 . Each of the discrete conductive regions  132  can be connected with the primary conductive region  118  by a conduction line  122 . A capacitor can be formed between each of the discrete conductive regions  132  and the substrate  120 . The discrete conductive regions  132  need not be configured for bonding with a circuit. Stated differently, the discrete conductive regions  132  can have dimensions that are not suitable for bonding, e.g., wire-bonding, with a circuit. Instead, the connection between the discrete conductive regions  132  and the primary conductive region  118  via the conduction lines  122  can provide additional capacitance to the overall capacitance value of the capacitor assembly  100 . 
     Each conductive region  132  can have a length  166  and a width  168 . In the embodiment illustrated in  FIGS.  1 - 2   , each of the conductive regions  132  has an approximately equal length  166  and width  168 . However, it is to be understood that the present invention contemplates a plurality of discrete conductive regions  132  which may have varying dimensions in terms of length  166  and width  168 . As the area, determined by the length  166  and width  168 , of each discrete conductive region  132  can determine the incremental capacitance value of each respective discrete capacitor, providing discrete conductive regions  132  having varying dimensions can enable the capacitor assembly to be tuned in varying increments to be customized and/or tuned to a precise capacitance value. 
     Nevertheless, it may be useful for each discrete conductive region  132  to have a length  166  and width  168  that are sufficiently sized to be visible on the surface  106  of the substrate  102 . The visibility of each discrete conductive region  132  can enable easier determination of how and where to trim the conduction line(s)  122  to achieve a precise capacitance value. 
     Thus, a ratio of the length  150  of the substrate  102  to a length  166  of any of the discrete conductive regions  132  can be less than about 50, such as less than about 20, e.g., less than about 10. A ratio of the length  150  of the substrate  102  to a length  166  of any of the discrete conductive regions  132  can be in a range from about 50:1, such as from about 20:1, such as from about 5:1. A ratio of the width  154  of the substrate  102  to the width  168  of any of the discrete conductive regions  132  can be less than about 50, such as less than about 20, e.g., less than about 10. A ratio of the width  154  of the substrate  102  to the width  168  of any of the discrete conductive regions  132  can be in a range from about 50:1, such as from about 20:1, such as from about 5:1. The present inventors have found that such distances and ratios can provide a capacitor assembly with a plurality of capacitive regions defined by each of the discrete conductive regions that can enable precision incremental tuning of the capacitance value of the capacitor assembly  100  in increments as small as about 0.05 pF. 
     As shown in  FIG.  2   , the conduction line  122  can be trimmed or severed between the first end  124  and the second end  126 . The trimmed portion  134  can be disposed within the trimming region  116 . 
     For instance,  FIG.  2    illustrates a capacitor assembly  100  having a plurality of discrete conductive regions  132   a ,  132   b ,  132   c ,  132   d  formed over the secondary oxide region  114 . Each of the discrete conductive regions  132   a ,  132   b ,  132   c ,  132   d  can have varying dimensions. For instance, as shown in  FIG.  2   , discrete conductive regions  132   a ,  132   b ,  132   c ,  132   d  can have a different length  166  in the X-direction. The present invention further contemplates that the discrete conductive regions  132   a ,  132   b ,  132   c ,  132   d  can have varying widths  168  in the Y-direction as well. 
     The directionality of the primary oxide region  112  and the primary conductive region  118  relative to the secondary oxide region  114  and the secondary conductive region  120  in the X-direction  10  and Y-direction  20  is not critical to the present invention. For instance,  FIGS.  1  and  2    illustrate the primary oxide region  112  and the primary conductive region  118  being spaced apart from the secondary oxide region  114  and the secondary conductive region  120  in the X-direction  10 . The present invention further contemplates arrangements of the capacitor assembly  100  in which the primary oxide region  112  and the primary conductive region  118  are spaced apart from the secondary oxide region  114  and the secondary conductive region  120  in the Y-direction  20 . Moreover, the present invention contemplates further arrangements of one or more secondary oxide regions  114  and secondary conductive regions  120  that can be spaced from the primary oxide region  112  and the primary conductive region  118  in one or both of the X-direction  10  and the Y-direction  20 . 
     The present invention further contemplates an insulator layer  140  formed over the oxide layer  104 , e.g., as shown in  FIG.  3   . The insulator layer  140  can be formed directly on the oxide layer  104 . For instance, the insulator layer  140  can be formed between the oxide layer  104  and the conductive layer  108 . The insulator layer  140  can extend over some or all of the oxide layer  104 , e.g., over some or all of the primary oxide region  112  and/or the secondary oxide region  114 . In some aspects of the present invention, the insulator layer  140  can be formed over the primary oxide region  112  and no insulator layer  140  formed over the secondary oxide region  114 . 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.