Patent Publication Number: US-11664270-B2

Title: Metal-insulator-metal (MIM) structure supporting high voltage applications and low voltage applications

Description:
CLAIM OF PRIORITY 
     This application is a Continuation of, and claims priority to, U.S. patent application Ser. No. 16/649,081, filed on Mar. 19, 2020 and titled “METAL-INSULATOR-METAL (MIM) STRUCTURE SUPPORTING HIGH VOLTAGE APPLICATIONS AND LOW VOLTAGE APPLICATIONS,” which is a National Stage Entry of, and claims priority to, PCT Application No. PCT/US2017/068551, filed on Dec. 27, 2017 and titled “METAL-INSULATOR-METAL (MIM) STRUCTURE SUPPORTING HIGH VOLTAGE APPLICATIONS AND LOW VOLTAGE APPLICATIONS,” which is incorporated by reference in its entirety for all purposes. 
    
    
     BACKGROUND 
     Integrated circuit chips often comprise passive components, such as capacitors, resistors, inductors, etc. Metal-Insulator-Metal (MIM) capacitor is a passive component that may be used in many applications, such as Radio Frequency (RF) applications, in analog integrated circuits, etc. MIM capacitors have attracted great attention because of their high capacitance density that supplies small area, increases circuit density, and further reduces the fabrication cost. 
     In many applications, it may be useful to have a MIM to be used as a capacitor in a relatively high voltage application, and an adjacent MIM to be used as a capacitor in a relatively low voltage application. In an example, in a conventional system, if both a high voltage MIM and a low voltage MIM are to be supported on a same wafer or process, this may require multiple mask layers (e.g., each mask layer to form a corresponding metal or insulator layer of a MIM), which may be costly and/or time consuming. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments of the disclosure will be understood more fully from the detailed description given below and from the accompanying drawings of various embodiments of the disclosure, which, however, should not be taken to limit the disclosure to the specific embodiments, but are for explanation and understanding only. 
         FIG.  1 A  illustrates a device comprising two adjacent MIMs, which may be configured for a high voltage operation and a low voltage operation, respectively, according to some embodiments. 
         FIG.  1 B  illustrates a plan view of a via surrounded by a spacer, according to some embodiments. 
         FIGS.  2 A,  2 B,  2 C,  2 D,  2 E,  2 F,  2 G,  2 H,  2 I,  2 J,  2 K,  2 L,  2 M, and  2 N  illustrate example processes for formation of the device of  FIG.  1 A , according to some embodiments. 
         FIG.  3    is flow diagrams illustrating a method of forming the device of  FIG.  1 A  comprising the MIM with the high voltage capacitor and the MIM with the low voltage capacitor, according to some embodiments. 
         FIG.  4    illustrates a computing device or a SoC (System-on-Chip) comprising a device including a MIM with a high voltage capacitor and a MIM with a low voltage capacitor, according to some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     MIM capacitors are a particular type of capacitor, having a top metal plate and a bottom metal plate separated by a capacitor dielectric, which are often implemented in integrated circuits. In an example, a MIM capacitor may have multiple stacked conductive layers, each separated from an adjacent one by an insulator layer. In many applications (e.g., circuits used for RF applications), it may be useful to have a MIM to be used as a capacitor in a relatively high voltage application, and an adjacent MIM to be used as a capacitor in a relatively low voltage application. 
     In an example, an electric field of a capacitor may be given by:
 
 E=V/d,   Equation 1,
 
     where E may be the electric field, V may be the applied voltage, and d may be a distance between adjacent conductive plates. 
     In an example, a capacitance C of a capacitor may be given by:
 
 C=ε·A/d,   Equation 2,
 
     where ε may be a permittivity associated with the capacitor, A may be an area of the capacitor, and d may be the distance between adjacent conductive plates. 
     In an example, an insulator may support limited electrical field, thereby limiting the value of E in equation 1. For example, for higher voltage application (e.g., high V in equation 1), the distance d may have to be increased. However, an increase in the distance d may result in a corresponding decrease in the capacitance. 
     In some embodiments, this disclosure discloses a device having a high voltage MIM capacitor formed adjacent to a low voltage MIM capacitor. In some embodiments, a via for the high voltage MIM capacitor has a larger width than the vias for the low voltage MIM capacitor. As discussed in further details herein, the difference in the dimensions of various vias allow for formation of the adjacent capacitors (e.g., on a same wafer, and using at least in part a same formation process). In some embodiments, the low voltage capacitor has at least a via passing through a conductive plate, without being in contact with the conductive plate (e.g., a spacer may block contact of the via from the conductive plate). Such designs and other features may allow formation of conductive and insulating layers of the high voltage capacitor MIM using a single mask, as discussed in further details herein. Similarly, conductive and insulating layers of the low voltage capacitor MIM may also be formed using a single mask, as discussed in further details herein. Thus, the principles of this disclosure may be used to reduce a number of masks for forming the device comprising the high voltage MIM and adjacent low voltage MIM, thereby resulting in cost, time and/or area improvements. Other technical effects will be evident from the various embodiments and figures. 
     In the following description, numerous details are discussed to provide a more thorough explanation of embodiments of the present disclosure. It will be apparent, however, to one skilled in the art, that embodiments of the present disclosure may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form, rather than in detail, in order to avoid obscuring embodiments of the present disclosure. 
     Note that in the corresponding drawings of the embodiments, signals are represented with lines. Some lines may be thicker, to indicate more constituent signal paths, and/or have arrows at one or more ends, to indicate primary information flow direction. Such indications are not intended to be limiting. Rather, the lines are used in connection with one or more exemplary embodiments to facilitate easier understanding of a circuit or a logical unit. Any represented signal, as dictated by design needs or preferences, may actually comprise one or more signals that may travel in either direction and may be implemented with any suitable type of signal scheme. 
     Throughout the specification, and in the claims, the term “connected” means a direct connection, such as electrical, mechanical, or magnetic connection between the things that are connected, without any intermediary devices. The term “coupled” means a direct or indirect connection, such as a direct electrical, mechanical, or magnetic connection between the things that are connected or an indirect connection, through one or more passive or active intermediary devices. The term “circuit” or “module” may refer to one or more passive and/or active components that are arranged to cooperate with one another to provide a desired function. The term “signal” may refer to at least one current signal, voltage signal, magnetic signal, or data/clock signal. The meaning of “a,” “an,” and “the” include plural references. The meaning of “in” includes “in” and “on.” The terms “substantially,” “close,” “approximately,” “near,” and “about,” generally refer to being within +/−10% of a target value. 
     Unless otherwise specified the use of the ordinal adjectives “first,” “second,” and “third,” etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking or in any other manner. 
     For the purposes of the present disclosure, phrases “A and/or B” and “A or B” mean (A), (B), or (A and B). For the purposes of the present disclosure, the phrase “A, B, and/or C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C). The terms “left,” “fight,” “front,” “back,” “top,” “bottom,” “over,” “under,” and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions. 
       FIG.  1 A  illustrates a device  100  comprising two adjacent MIMs  100   a  and  100   b , which may be configured for a high voltage operation and a low voltage operation, respectively, according to some embodiments. The MIM  100   a  may be configured for high voltage operation, where the high voltage may be, merely as an example, 5 Volts (V) or higher. The MIM  100   b  may be configured for low voltage operation, where the low voltage may be, merely as an example, less than 5 V. In some embodiments, the MIMs  100   a  and  100   b  are configured as two respective capacitors. 
     In some embodiments, the MIM  100   a  comprises conductive layers  104   a  and  104   b , and insulating layers  108   a  and  108   b , arranged in an interleaved stack. In some embodiments, the MIM  100   b  comprises conductive layers  104   c  and  104   d , and insulating layers  108   c  and  108   b , arranged in an interleaved stack. Thus, the insulating layer  108   b  may be common to both the MIMs  100   a  and  100   b . Although  FIG.  1 A  illustrates two conductive layers and two insulating layers in each of the MIMs  100   a  and  100   b , in some embodiments, the principles of this disclosure can be applied to MIMs comprising higher number of stacked conductive layers  104  and insulating layers  108 . 
     Elements referred to herein with a common reference label followed by a particular number or alphabet may be collectively referred to by the reference label alone. For example, conductive layers  104   a ,  104   b ,  104   c ,  104   d  may be collectively and generally referred to as conductive layers  104  in plural, and conductive layer  104  in singular. Similarly, insulating layers  108   a ,  108   b ,  108   c  may be collectively and generally referred to as insulating layers  108  in plural, and insulating layer  108  in singular. 
     In some embodiments and as discussed in further details herein, the conductive layers  104   c  and  104   d  are of a single continuous conductive layer (e.g., the conductive layers  104   c  and  104   d  may be formed by selectively etching the single continuous conductive layer). In an example, the conductive layers  104   c  and  104   d  may be referred to herein as part of a same layer. For example, the conductive layers  104   c  and  104   d  may be referred to herein as an upper layer of the MIMs  100   a  and  100   b , respectively. Similarly, for example, the conductive layers  104   b  and  104   d  may be referred to herein as a middle layer of the MIMs  100   a  and  100   b , respectively. In example, the insulating layers  108   a  and  108   c  may be formed by etching and dividing a single insulating layer. Thus, the insulating layers  108   a  and  108   c  may be referred to herein as a first insulating layer of the MIMs  100   a  and  100   b , respectively (e.g., the insulating layers  108   a  and  108   c  may be referred to using a common label, such as a first insulating layer). In an example, the insulating layer  108   b  may be referred to herein as a second insulating layer of the MIMs  100   a  and  100   b , respectively. 
     In some embodiments, heights of the conductive layers  104   a  and  104   c  along the Z axis in  FIG.  1 A  are similar (e.g., as both the conductive layers  104   a  and  104   c  may be of a same conductive layer, as discussed herein), e.g., with ±10% of each other; a height of the conductive layers  104   b  and  104   d  may be similar (e.g., with ±10% of each other); and a height of the insulating layers  108   a  and  108   c  may be similar (e.g., with ±10% of each other). 
     In some embodiments and as illustrated in  FIG.  1 A , a thickness or height of the insulating layer  108   b  (e.g., along a Z axis) is larger than thicknesses or heights of one or more of the conductive layers  104   a ,  104   b ,  104   c ,  104   d  and/or the insulating layers  108   a  and  108   c . For example, the height of the insulating layer  108   b  may be at least double or more than the heights of the conductive layers  104   a ,  104   b ,  104   c ,  104   d  and/or the insulating layers  108   a  and  108   c . In another example, the height of the insulating layer  108   b  may be up to about 10 times the heights of the conductive layers  104   a ,  104   b ,  104   c ,  104   d  and/or the insulating layers  108   a  and  108   c . For example, because the high voltage capacitor is formed using the insulating layer  108   b , the height of the insulating layer  108   b  may be relatively larger. In contrast, because the low voltage capacitor is formed using the insulating layer  108   c , the height of the insulating layer  108   c  may be relatively smaller. In some embodiments, the heights of the insulating layers  108   b  and  108   c  is based on the voltage ratings of the high voltage capacitor and the low voltage capacitor, respectively. 
     In some embodiments, the insulating layer  108   b  has a higher breakdown voltage than one or both of the insulating layers  108   a  and  108   c . For example, a breakdown voltage of a layer may be based on a composition of the layer, a thickness of the layer, a dielectric strength of the layer, etc. As the thickness or height of the insulating layer  108   b  is larger than thicknesses or heights of the insulating layers  108   a  and  108   c , the insulating layer  108   b  has a higher breakdown voltage than the insulating layers  108   a  and  108   c.    
     In some embodiments, sizes of the stacked layers  104  and  108  determine a capacitance of the MIMs  100   a  and  100   b , and the size of individual ones of the stacked layers  104  and  108  is based on a desired capacitance of the MIMs  100   a  and  100   b . In some embodiments, the dimensions (e.g., length and width, but not necessarily the height) of the layers  104   a ,  108   a , and  104   b  are similar (e.g., the dimensions of these layers may be within 5% of each other), e.g., as these layers may be formed using a single mask, as discussed in further details herein. In some embodiments, the dimensions (e.g., length and width, but not necessarily the height) of the layers  104   c ,  108   c , and  104   d  are similar (e.g., the dimensions of these layers may be within 5% of each other), e.g., as these layers may be formed using a single mask, as discussed in further details herein. 
     In some embodiments, the conductive layers  104  include conductive material, such as, but not limited to, one or more of platinum (Pt), aluminum-copper (AlCu), titanium nitride (TiN), gold (Au), titanium (Ti), tantalum (Ta), tantalum nitride (TaN), tungsten (W), tungsten nitride (WN), copper (Cu), and/or the like. In some embodiments, the insulating layers  108  include insulating or dielectric material, such as, but not limited to, one or more of nickel oxide (NiO), titanium oxide (TiO), hafnium oxide (HfO), zirconium oxide (ZrO), zinc oxide (ZnO), tungsten oxide (WO3), aluminum oxide (Al2O3), tantalum oxide (TaO), molybdenum oxide (MoO), copper oxide (CuO), silicon dioxide (SiO2), silicon nitride (Si3 N4), polymide, and/or the like. 
     In some embodiments, the MIMs  100   a ,  100   b  are formed over an Inter-layer Dielectric (ILD)  112 . For example, a bottom side of the MIMs  100   a ,  100   b  may be encapsutaed by the ILD  112 . In some embodiments, a top side of the MIMs  100   a ,  100   b  (e.g., which may be opposite the bottom side) are encapsulated by ILD  122 . Any appropriate dielectric material (e.g., low k dielectric material) may be used for the ILDs  112  and  122 . 
     In some embodiments, the MIM  100   a  includes a conductive layer  116 , which may form a bottom electrode of the MIM  100   a  (e.g., the conductive layer  116  may also be referred to as bottom electrode  116 , or simply as electrode  116 , of the MIM  100   a ). The electrode  116  may be form on the insulating layer  108   b , and may be aligned to be underneath the stack comprising the layers  104   a ,  108   a , and  104   b . The electrode  116  may include conductive material, such as, but not limited to, one or more of platinum (Pt), aluminum-copper (AlCu), titanium nitride (TiN), gold (Au), titanium (Ti), tantalum (Ta), tantalum nitride (TaN), tungsten (W), tungsten nitride (WN), copper (Cu), and/or the like. Merely as an example, the electrode  116  may comprise copper. 
     In some embodiments, the device  100  includes an interconnect layer  120  including conductive material such as, but not limited to, one or more of platinum (Pt), aluminum-copper (AlCu), titanium nitride (TiN), gold (Au), titanium (Ti), tantalum (Ta), tantalum nitride (TaN), tungsten (W), tungsten nitride (WN), copper (Cu), and/or the like. Merely as an example, the interconnect layer  120  includes copper. In some embodiments, the interconnect layer  120  is not aligned (e.g., may not be underneath) the stack comprising the layers  104   a ,  108   a , and  104   b , or the stack comprising the layers  104   c ,  108   c , and  104   d.    
     In some embodiments, the MIM  100   a  comprises a via  128  that is at least in part through the stack comprising the layers  104   a ,  108   a , and  104   b . For example, the via  128  may extend through the conductive layer  104   a  and the insulating layer  108   a , and may be in contact with the conductive layer  104   b  (e.g., may extend partially or fully through the conductive layer  104   b ). In an example, the via  128  may be in contact with the insulating layer  108   b . In some embodiments, the via  128  is not in contact with the electrode  116  (e.g., the via may not extend through the insulating layer  108   b ). Thus, in an example, the via  128  may electrically connect the conductive layers  104   a  and  104   b.    
     In some embodiments, the insulating layer  108   b  separates the conductive layer  104   b  from the electrode  116 . In some embodiments, when voltage is applied between the via  128  and the electrode  116 , a capacitance is formed between the conductive layer  104   b  and the electrode  116  of the MIM  100   a . In an example, as the insulating layer  108   b  may be relatively thick (e.g., having height larger than the height of the insulating layer  108   c ), the capacitor developed between the conductive layer  104   b  and the electrode  116  of the MIM  100   a  may be able to handle relatively higher voltage (e.g., compared to that of the MIM  100   b ). It may be noted that as the conductive layers  104   a  and  104   b  are connected by the via  128 , these two conductive layers may be at similar potential. 
     Thus, in some embodiments, upper conductive layer  104   a , middle conductive layer  104   b  and lower conductive layer (or electrode)  116  may form a capacitor stack (e.g., along with the interleaved insulating layers  108   a  and  108   b ) associated with the MIM  100   a . As discussed, this capacitor stack may be rated for relatively higher voltage (e.g., compared to that of the MIM  100   b ). 
     In some embodiments, the MIM  100   b  comprises a first via  138  and a second via  168 . The first via  138  may extend at least in part through the stack comprising the layers  104   c ,  108   c ,  104   d ,  108   b . For example, in the embodiment of  FIG.  1 A , the first via  138  extends through the layers  104   c ,  108   c ,  104   d ,  108   b , and may be partially through the ILD  112 . In another embodiment, the first via  138  extends through the layers  104   c ,  108   c , and is in contact with, partially extend, or fully extend through the layer  104   d . In another embodiment, the first via  138  extends through the layers  104   c ,  108   c ,  104   d , and is in contact with, partially extend, or fully extend through the layer  108   b.    
     In some embodiments, the via  138  is coupled to (e.g., in direct contact with, and attached to) the conductive layer  104   d . In some embodiments, the via  138  is not in contact with the conductive layer  104   c . For example, one or more spacers  130  may isolate (e.g., physically and/or electrically isolate) the via  138  from the conductive layer  104   c . For example, the spacer  130  may be between one or more sidewalls of the conductive layer  104   c  and a portion of the via  138  that extends through the conductive layer  104   c . For example, the spacer  130  may act as a blocking layer to block or isolate the via  138  from the conductive layer  104   c . In an example, the spacer  130  may also partially or fully isolate the via  138  from the insulating layer  108   c . Thus, the spacer  130  may result in the via  138  being in contact with the conductive layer  104   d , while being isolated from the conductive layer  104   c.    
       FIG.  1 B  illustrates a plan view of the via  138  surrounded by the spacer  130 , according to some embodiments. For example, the plan view of  FIG.  1 B  may be along the line A of  FIG.  1 A . As illustrated in  FIG.  1 B , the spacers  130  may isolate the via  138  from the conductive layer  104   c . For example, the spacer  130  may be between one or more sidewalls of the conductive layer  104   c  and a portion of the via  138  that extends through the conductive layer  104   c.    
     Referring again to  FIG.  1 A , in some embodiments, the via  168  of the MIM  100   b  is in contact with the conductive layer  104   c , while being isolated from the conductive layer  104   d . For example, the via  168  may be in direct contact with, or at least partially or fully penetrate, the conductive layer  104   c.    
     In some embodiments, the insulating layer  108   c  separates the conductive layer  104   c  from the conductive layer  104   d . In some embodiments, when voltage is applied between the via  138  and the via  168 , a capacitance is formed between the conductive layers  104   c  and  104   d . In an example, as the insulating layer  108   c  may be relatively thin (e.g., having height smaller than the height of the insulating layer  108   b ), the capacitor developed between the conductive layers  104   c  and  104   d  of the MIM  100   b  may be able to handle relatively lower voltage (e.g., compared to that of the MIM  100   a ). In an example, the conductive layer  108   b  may not be used for developing the capacitance in the MIM  100   b.    
     Thus, in some embodiments, upper conductive layer  104   c  and middle conductive layer  104   d  may form a capacitor stack (e.g., along with the interleaved insulating layers  108   c  and  108   b ) associated with the MIM  100   b . As discussed, this capacitor stack may be rated for relatively lower voltage (e.g., compared to that of the MIM  100   a ). 
     Thus, in an example, the capacitor formed using the MIM  100   a  may be used for higher voltage applications, and the capacitor formed using the MIM  100   b  may be used for lower voltage applications. In an example, the high and low voltage capacitors may coexist adjacent to each other in the same chip. 
     In some embodiments, the spacer  130  has high breakdown voltage. For example, the breakdown voltage of the spacer  130  exceeds the breakdown voltage of the insulator layer  108   c , e.g., so that the spacer  130  can withstand higher voltage than the insulating layer  108   c , where the insulating layer  108   c  forms a part of the capacitor associated with the MIM  100   b.    
     In some embodiments, the interconnect layer  120  is coupled to vias  148  and  158 . The interconnect layer  120  may form an interconnection between the vias  148  and  158 . In some embodiments, the vias  148  and  158  respectively comprise spacers  140  and  150  (e.g., as a byproduct of forming the spacers on the via  138 ). In an example, the spacers  148 ,  158  may not be used for any isolation purposes. In some other embodiments and although not illustrated in  FIG.  1 A , the spacers  140  and  150  are absent from the device  100 . In some other embodiments and although not illustrated in  FIG.  1 A , the interconnect layer  120  and/or the vias  148  and  158  are absent from the device  100 . 
     In some embodiments, the via  128  has a width (e.g., a cross-sectional diameter) of about m1; one or more of the vias  138 ,  148 , and  158  has a width (e.g., a cross-sectional diameter) of about m2; and the via  168  has a width (e.g., a cross-sectional diameter) of about m3. In some embodiments, the dimensions m1, m2, and m3 are substantially different, e.g., m1 may be higher than m2, and m2 may be higher than m3. For example, m1 may be at least double or more than m2, and m2 may be at least double or more than m3. The difference in the dimensions m1, m2, and m3 may facilitate selective isolation of the vias  128 - 168 , such that a sidewall of via  128  is unlined (e.g., by spacers  130 - 150 ) and continuity with both conductive layers  104   a  and  104   b  is maintained. 
     Although the components  128 ,  138 ,  148 ,  158 , and  168  are referred to as vias, these components may also be referred to as metal plugs, interconnection structures, and/or the like. 
     Although the insulating layer  108   b  is illustrated to be a continuous layer among the two capacitor stacks of the two MIMs  100   a  and  100   b , in some embodiments (and although not illustrated in  FIG.  1 A ), the insulating layer  108   b  may also be separated to form two discontinuous layers for the two respective capacitor stacks. 
     In some embodiments and although not illustrated in  FIG.  1 A , the thickness of the insulating layer  108   b  can be swapped with the thickness of the insulating layers  108   a  and  108   c . In such an embodiment, the insulating layer  108   b  is thinner than the insulating layers  108   a  and  108   c . In such embodiments, for example, the via  128  is in contact with the conductive layer  104   a , but not in contact with the conductive layer  104   b  (e.g., similar to the via  168  of  FIG.  1 A ), and the electrode  116  extends through the bottom insulating layer  108   b  and is in contact with the conductive layer  104   b . Positions and/or thicknesses of various layers and/or vias of the device  100  may be altered in some example. 
       FIG.  2 A- 2 N  illustrate example processes for formation of the device  100  of  FIG.  1 A , according to some embodiments. For example,  FIGS.  2 A- 2 N  are cross-sectional views of the device  100  evolving as example operations for formation of the device  100  are performed. 
     Referring to  FIG.  2 A , multiple interleaved and stacked conductive layers  204   a ,  204   b , and insulating layers  208   a ,  108   b  may be formed over the ILD  112 . The stack of the conductive layers  204   a ,  204   b , and the insulating layers  208   a ,  108   b  may be formed by deposition of thin films of conductive and insulating material. In some embodiments, the conductive layer  116  and the interconnect layer  120  are formed at appropriate positions underneath the insulating layer  108   b.    
     Referring now to  FIG.  2 B , the stack of the conductive layers  204   a ,  204   b , and insulating layers  208   a ,  108   b  may be etched to form a first stack  203   a  and a second stack  203   b . The first stack  203   a  may comprise conductive layer  104   a , insulating layer  108   a , conductive layer  104   b , and insulating layer  108   b ; and the second stack  203   b  may comprise conductive layer  104   c , insulating layer  108   c , conductive layer  104   d , and insulating layer  108   b . For example, the conductive layer  204   a  of  FIG.  2 A  may be etched to form the conductive layers  104   a  and  104   c  of  FIG.  2 B ; the insulating layer  208   a  of  FIG.  2 A  may be etched to form the insulating layers  108   a  and  108   c  of  FIG.  2 B ; and the conductive layer  204   b  of  FIG.  2 A  may be etched to form the conductive layers  104   b  and  104   d  of  FIG.  2 B . The two stacks  203   a  and  203   b  may be adjacent to, but separate from each other, as illustrated in  FIG.  2 B . 
     The two stacks  203   a ,  203   b  of  FIG.  2 B  may be formed by, for example, lithography using patterning and etching. The stack of  FIG.  2 A  may be etched, e.g., using a mask, to form the stacks  203   a  and  203   b . In some embodiments, because the stack  203   a  may be formed using a single mask, the layers  104   a ,  108   a ,  104   b  are of similar dimensions (e.g., similar length and width) and are aligned (e.g., not offset with respect to each other), as discussed with respect to  FIG.  1 A . In some embodiments, because the stack  203   b  may be formed using a single mask, the layers  104   c ,  108   c ,  104   d  are of similar dimensions (e.g., similar length and width) and are aligned (e.g., not offset with respect to each other), as discussed with respect to  FIG.  1 A . 
     Thus, the layers  104   a  and  104   c  are formed from a same layer  204   a . In an example, the layers  104   a  and  104   c  are referred to as an upper layer of two separate capacitor stacks associated with the two MIMs  100   a  and  100   b . Similarly, for example, the conductive layers  104   b  and  104   d  may be referred to herein as a middle layer of the MIMs  100   a  and  100   b , respectively. Similarly, for example, the insulating layers  108   a  and  108   c  may be referred to herein as a first insulating layer of the MIMs  100   a  and  100   b , respectively; and the insulating layer  108   b  may be referred to herein as a second insulating layer of the MIMs  100   a  and  100   b , respectively. 
     Although the insulating layer  108   b  is illustrated to be a continuous layer among the two capacitor stacks of the two MIMs  100   a  and  100   b , in some embodiments (and although not illustrated in the figures), the insulating layer  108   b  may also be etched to form two separate discontinuous layers for the two respective capacitor stacks. 
     Referring now to  FIG.  2 C , a ILD layer  122  may be deposited to encapsulate the stacks  203   a  and  203   b . Subsequently, a hard mask layer  124  may be deposited on the ILD layer  122 . Photoresist layer  201  comprising photoresist material may be patterned over the hard mask layer  124 . In some embodiments, a first opening  228  (e.g., which may be over an eventual position of the via  128 ) in the photoresist layer  201  over the stack  203   a  has a diameter of a1. A second opening  238  and a third opening  268  (e.g., which may be over eventual positions of the vias  138  and  168 , respectively) in the photoresist layer  201  over the stack  203   a  may have diameters of a2 and a3, respectively. A fourth opening  248  and a fifth opening  258  (e.g., which may be in eventual positions of the vias  148  and  158 , respectively) in the photoresist layer  201  over the interconnect layer  120  may have diameters of about a2. In some embodiments, a1 is larger than a2, and a2 is larger than a3. For example, a1 may be at least double or more than a2, and a2 may be at least double or more of a3. The difference in the dimensions a1, a2, and a3 may facilitate the formation of the various vias, e.g., as discussed herein in further detail. 
     Referring now to  FIG.  2 D , hark mask layer  124  exposed through the photoresist layer  201  may be etched, and the photoresist layer  201  may then be removed, thereby transferring the pattern into the hark mask layer  124 . Thus, the hard mask layer  124  may have various openings, e.g., similar to the openings of the photoresist layer  201  discussed herein above. 
     Referring now to  FIG.  2 E , a conformal hard mask layer  205  may be deposited (e.g., conformally deposited) on the hard mask layer  124 , e.g., using thin-film deposition methods, such as plating, chemical vapor deposition, atomic layer deposition, and/or the like. The conformal hard mask layer  205  may then be etched, for example, anisotropically. In some embodiments, as the width a1 of the opening  228  is larger than the widths a2 and a3 of the other openings  238 ,  248 ,  258 ,  268 , the conformal hard mask layer  205  forms a ridge, recess or low depth region within the opening  228 . Etching of the conformal hard mask layer  205  may expose the ILD  112  through the opening  228 , as illustrated in  FIG.  2 E . Because of the relatively low width of the other openings  238 ,  248 ,  258 ,  268  of the hard mask  124  (e.g., openings having width of a2 and a3), the deposition and etching of the conformal hard mask layer  205  may not expose the ILD  112  through these openings. Thus, due to the difference in the sizes of the various openings (e.g., as indicated in  FIGS.  2 C and  2 D ), the ILD  122  may be exposed only through the opening  228  (and not exposed through the other openings). 
     Referring now to  FIG.  2 F , the ILD  122 , the conductive layer  104   a  and the insulating layer  108   a  may be selectively etched through the opening  228 . The etching in  FIG.  2 F  may be performed using any appropriate etching technique, e.g., dry etch, wet chemical etch, etc. The etchants used may be selective to the material of the conductive layers  104  and the insulating layer  108 . Merely as an example, initially a selective etchant may be used to etch the ILD  122  underneath the opening  228 . Subsequently, another selective etchant may be used to etch the conductive layer  104   a  underneath the opening  228 . Finally, yet another selective etchant may be used to etch the insulating layer  108   a  underneath the opening  228 . 
     Referring now to  FIG.  2 G , a sacrificial material  229  may be deposited in the opening  228 . Subsequently, the conformal hard mask layer  205  may be removed (e.g., may be isotropically etched or stripped), thereby recovering the openings  238 ,  248 ,  258 ,  268 , as illustrated in  FIG.  2 G . 
     Referring now to  FIG.  2 H , a conformal hard mask layer  211  may be deposited (e.g., conformally deposited) on the hard mask layer  124 , e.g., using thin-film deposition methods, such as plating, chemical vapor deposition, atomic layer deposition, and/or the like. The conformal hard mask layer  211  may then be etched. In some embodiments, as the width a2 of the openings  238 ,  248 ,  258  is larger than the width a3 of the opening  268 , the conformal hard mask layer  211  forms a ridge, recess or low depth region within the opening  238 ,  248 ,  258 . Etching of the conformal hard mask layer  211  may expose the ILD  112  through the openings  238 ,  248 ,  258 , as illustrated in  FIG.  2 H . Because of the relatively low width of the opening  268  of the hard mask  124  (e.g., opening having width of a3), the deposition and etching of the conformal hard mask layer  211  may not expose the ILD  112  through this opening, as illustrated in  FIG.  2 H . Thus, due to the difference in the sizes of the various openings (e.g., as indicated in  FIGS.  2 C and  2 D ), the ILD  122  may be exposed only through the openings  238 ,  248 ,  258  of the hard mask layer  124  (and not exposed through the opening  268 ). 
     Referring now to  FIG.  2 I , the ILD  122 , the conductive layers  104   c ,  104   d , the insulating layers  108   c ,  108   b  (and optionally at least a part of IDL  122 ) may be selectively etched through the opening  238 . In some embodiments, the ILD  122  also is selectively etched through the openings  248  and  258 . The etching in  FIG.  2 I  may be performed using any appropriate etching technique, e.g., dry etch, wet chemical etch, etc., using one or more selective etchants (e.g., as discussed with respect to  FIG.  2 F ). In some embodiments, spacers  130  are deposited within sections of the sidewalls of the opening  238 , e.g., such that the spacers  130  may block the conductive layer  130  (and may also optionally at least partially or fully block through the insulating layer  108   c ) from the opening  238 . 
     Merely as an example (and although not illustrated in the figures), the opening  238  may be initially extended through the ILD  122  and the layers  104   c  and  108   c  (but not though the layers  104   d ,  108   b ). Subsequently, the spacers  130  may be formed through the opening  238  on the sidewalls of the ILD  122  and the layers  104   c ,  108   c ,  104   d . Sections of the spacers  130  may then be selectively etched from the sidewalls of the ILD  122  and the hard mask layer  211 , but other sections of the spacers  130  may remain on the sidewalls of the layers  108   c ,  104   c . Then the opening  238  may be extended through the layers  104   d ,  108   b , and possibly through the ILD  112 , as illustrated in  FIG.  2 I . Examples of deposition of spacers on selective sections of sidewalls of an opening are discussed in further detail in co-pending U.S. patent application Ser. No. 16/651,296. In some embodiments, spacers  140  and  150  are deposited within sections of the sidewalls of the openings  248  and  258 , respectively. 
     Referring now to  FIG.  2 J , sacrificial material  239 ,  249 , and  259  may be respectively deposited in the openings  238   248 , and  258 , and the conformal hard mask layer  211  may be removed (e.g., may be etched), thereby recovering the opening  268 . 
     Referring now to  FIG.  2 K , a conformal hard mask layer  215  may be deposited on the hard mask layer  124 , e.g., using thin-film deposition methods, such as plating, chemical vapor deposition, atomic layer deposition, and/or the like. The conformal hard mask layer  215  may then be etched. In some embodiments, the conformal hard mask layer  215  are deposited in the opening  268 , as well as the small openings adjacent to the sacrificial materials  229 ,  239 ,  249 , and  259 . However, the width a3 of the opening  268  may be larger than the width of the openings adjacent to the sacrificial materials  229 ,  239 ,  249 , and  259 . Thus, the conformal hard mask layer  215  may form a ridge, recess or low depth region within the opening  268 . Etching of the conformal hard mask layer  215  may expose the ILD  112  through the opening  268 , as illustrated in  FIG.  2 K . 
     Referring now to  FIG.  2 L , the ILD  122  may be selectively etched through the opening  268 . The etching in  FIG.  2 L  may be performed using any appropriate etching technique, e.g., dry etch, wet chemical etch, etc., using one or more selective etchants (e.g., as discussed with respect to  FIG.  2 F ). In some embodiments, the opening  268  is now in contact with (and possibly partially or fully extending through, although not illustrated in the figures) the conductive layer  104   c.    
     Referring now to  FIG.  2 M , the sacrificial materials  229 ,  239 ,  249 , and  259  may be removed by an appropriate selective etching process. In some embodiments, the conformal hard mask layer  215  is also removed, as illustrated in  FIG.  2 M . 
     Referring now to  FIG.  2 N , the openings  228 ,  238 ,  248 ,  258 , and  268  are respectively filled with conductive material (e.g., metal) to form vias  128 ,  138 ,  148 ,  158 , and  168 . The device  100  in  FIG.  2 N  is similar to the device  100  of  FIG.  1 A . 
     Thus, referring now to  FIGS.  1 A- 2 N , in some embodiments, the device  100  comprises a high voltage capacitor formed using the MIM  100   a , and an adjacent low voltage capacitor formed using the MIM  100   b . For example, a capacitor may be formed between the conductive layer  104   b  and the electrode  116  of the MIM  100   a . As the insulating layer  108   b  may be relatively thick (e.g., having height higher than the height of the insulating layer  108   c ), the capacitor developed between the via  128  and the electrode  116  of the MIM  100   a  may be able to handle relatively higher voltage (e.g., compared to that of the MIM  100   b ). Similarly, a capacitor may be formed between the conductive layers  104   c  and  104   d . As the insulating layer  108   c  may be relatively thin (e.g., having height lower than the height of the insulating layer  108   b , as a result of which the insulating layers  108   b  may have a higher breakdown voltage than one or both of the insulating layers  108   a  and  108   c ), the capacitor developed between the conductive layers  104   c  and  104   d  of the MIM  100   b  may be able to handle relatively lower voltage (e.g., compared to that of the MIM  100   a ). In some embodiments, a capacitance per unit area of the capacitor of the MIM  100   a  is lower than a capacitance per unit area of second capacitor of the MIM  100   b.    
       FIG.  3    is flow diagrams illustrating a method  300  of forming the device  100  of  FIG.  1 A  comprising the MIM  100   a  with the high voltage capacitor and the MIM  100   b  with the low voltage capacitor, according to some embodiments. Although the blocks in the flowchart with reference to  FIG.  3    are shown in a particular order, the order of the actions can be modified. Thus, the illustrated embodiments can be performed in a different order, and some actions/blocks may be performed in parallel. Some of the blocks and/or operations listed in  FIG.  3    may be optional in accordance with certain embodiments. The numbering of the blocks presented is for the sake of clarity and is not intended to prescribe an order of operations in which the various blocks must occur. 
     In some embodiments, the method  300  comprises, at  304 , forming a first interleaved stack of a first plurality of layers (e.g., conductive layers  104   a  and  104   b ) comprising conductive material and a second plurality of layers (e.g., insulating layer  108   a  and  108   b ) comprising insulating material. The method further comprises, at  308 , forming a second interleaved stack of a third plurality of layers (e.g., conductive layers  104   c  and  104   d ) comprising conductive material and a fourth plurality of layers comprising insulating material (e.g., insulating layer  108   c  and  108   b ). 
     The method further comprises, at  312 , forming a first via (e.g., via  128 ) through one or more layers of the first stack, the first via coupled to two of the first plurality of layers. The method further comprises, at  316 , forming a second via (e.g., via  138 ) through one or more layers of the second stack, the second via isolated from a first layer (e.g., conductive layer  104   c ) of the third plurality of layers and coupled to a second layer (e.g., conductive layer  104   d ) of the third plurality of layers. The method further comprises, at  320 , forming a third via (e.g., via  168 ) that is coupled to the first layer of the third plurality of layers and isolated from the second layer of the third plurality of layers. 
     In some embodiments, forming the first via comprises: forming an ILD (e.g., ILD  122 ) over the first interleaved stack and the second interleaved stack; forming a hard mask layer (e.g., hard mask layer  201 ) over the ILD, the hard mask layer comprising: a first opening (e.g., opening  228 ) for formation of the first via, a second opening (e.g., opening  238 ) for formation of the second via, and a third opening (e.g., opening  268 ) for formation of the third via; depositing a conformal hard mask layer (e.g., conformal hard mask layer  205 ) over the hard mask layer; etching the conformal hard mask layer such that: the conformal hard mask layer does not fully cover the first opening, and the ILD is exposed through the first opening, and the conformal hard mask layer substantially covers the second and third openings, and the ILD is not exposed through the second and third openings (e.g., as illustrated in  FIG.  2 E ); and selectively etching the ILD and the first interleaved stack to extend the first opening, without affecting the second or third openings (e.g., as illustrated in  FIG.  2 F ), wherein the first via is formed in the extended first opening. 
       FIG.  4    illustrates a computing device or a SoC (System-on-Chip)  2100  comprising a device (e.g., device  100  of  FIG.  1 A ) including a MIM (e.g., the MIM  100   a ) with a high voltage capacitor and a MIM (e.g., the MIM  100   b ) with a low voltage capacitor, according to some embodiments. It is pointed out that those elements of  FIG.  4    having the same reference numbers (or names) as the elements of any other figure can operate or function in any manner similar to that described, but are not limited to such. 
     In some embodiments, computing device  2100  represents an appropriate computing device, such as a computing tablet, a mobile phone or smart-phone, a laptop, a desktop, an IOT device, a server, a set-top box, a wireless-enabled e-reader, or the like. It will be understood that certain components are shown generally, and not all components of such a device are shown in computing device  2100 . 
     In some embodiments, computing device  2100  includes a first processor  2110 . The various embodiments of the present disclosure may also comprise a network interface within  2170  such as a wireless interface so that a system embodiment may be incorporated into a wireless device, for example, cell phone or personal digital assistant. 
     In one embodiment, processor  2110  can include one or more physical devices, such as microprocessors, application processors, microcontrollers, programmable logic devices, or other processing means. The processing operations performed by processor  2110  include the execution of an operating platform or operating system on which applications and/or device functions are executed. The processing operations include operations related to I/O with a human user or with other devices, operations related to power management, and/or operations related to connecting the computing device  2100  to another device. The processing operations may also include operations related to audio I/O and/or display I/O. 
     In one embodiment, computing device  2100  includes audio subsystem  2120 , which represents hardware (e.g., audio hardware and audio circuits) and software (e.g., drivers, codecs) components associated with providing audio functions to the computing device. Audio functions can include speaker and/or headphone output, as well as microphone input. Devices for such functions can be integrated into computing device  2100 , or connected to the computing device  2100 . In one embodiment, a user interacts with the computing device  2100  by providing audio commands that are received and processed by processor  2110 . 
     Display subsystem  2130  represents hardware (e.g., display devices) and software (e.g., drivers) components that provide a visual and/or tactile display for a user to interact with the computing device  2100 . Display subsystem  2130  includes display interface  2132 , which includes the particular screen or hardware device used to provide a display to a user. In one embodiment, display interface  2132  includes logic separate from processor  2110  to perform at least some processing related to the display. In one embodiment, display subsystem  2130  includes a touch screen (or touch pad) device that provides both output and input to a user. 
     I/O controller  2140  represents hardware devices and software components related to interaction with a user. I/O controller  2140  is operable to manage hardware that is part of audio subsystem  2120  and/or display subsystem  2130 . Additionally, I/O controller  2140  illustrates a connection point for additional devices that connect to computing device  2100  through which a user might interact with the system. For example, devices that can be attached to the computing device  2100  might include microphone devices, speaker or stereo systems, video systems or other display devices, keyboard or keypad devices, or other I/O devices for use with specific applications such as card readers or other devices. 
     As mentioned above, I/O controller  2140  can interact with audio subsystem  2120  and/or display subsystem  2130 . For example, input through a microphone or other audio device can provide input or commands for one or more applications or functions of the computing device  2100 . Additionally, audio output can be provided instead of, or in addition to display output. In another example, if display subsystem  2130  includes a touch screen, the display device also acts as an input device, which can be at least partially managed by I/O controller  2140 . There can also be additional buttons or switches on the computing device  2100  to provide I/O functions managed by I/O controller  2140 . 
     In one embodiment, I/O controller  2140  manages devices such as accelerometers, cameras, light sensors or other environmental sensors, or other hardware that can be included in the computing device  2100 . The input can be part of direct user interaction, as well as providing environmental input to the system to influence its operations (such as filtering for noise, adjusting displays for brightness detection, applying a flash for a camera, or other features). 
     In one embodiment, computing device  2100  includes power management  2150  that manages battery power usage, charging of the battery, and features related to power saving operation. Memory subsystem  2160  includes memory devices for storing information in computing device  2100 . Memory can include nonvolatile (state does not change if power to the memory device is interrupted) and/or volatile (state is indeterminate if power to the memory device is interrupted) memory devices. Memory subsystem  2160  can store application data, user data, music, photos, documents, or other data, as well as system data (whether long-term or temporary) related to the execution of the applications and functions of the computing device  2100 . In one embodiment, computing device  2100  includes a clock generation subsystem  2152  to generate a clock signal. 
     Elements of embodiments are also provided as a machine-readable medium (e.g., memory  2160 ) for storing the computer-executable instructions (e.g., instructions to implement any other processes discussed herein). The machine-readable medium (e.g., memory  2160 ) may include, but is not limited to, flash memory, optical disks, CD-ROMs, DVD ROMs, RAMs, EPROMs, EEPROMs, magnetic or optical cards, phase change memory (PCM), or other types of machine-readable media suitable for storing electronic or computer-executable instructions. For example, embodiments of the disclosure may be downloaded as a computer program (e.g., BIOS) which may be transferred from a remote computer (e.g., a server) to a requesting computer (e.g., a client) by way of data signals via a communication link (e.g., a modem or network connection). 
     Connectivity  2170  includes hardware devices (e.g., wireless and/or wired connectors and communication hardware) and software components (e.g., drivers, protocol stacks) to enable the computing device  2100  to communicate with external devices. The computing device  2100  could be separate devices, such as other computing devices, wireless access points or base stations, as well as peripherals such as headsets, printers, or other devices. 
     Connectivity  2170  can include multiple different types of connectivity. To generalize, the computing device  2100  is illustrated with cellular connectivity  2172  and wireless connectivity  2174 . Cellular connectivity  2172  refers generally to cellular network connectivity provided by wireless carriers, such as provided via GSM (global system for mobile communications) or variations or derivatives, CDMA (code division multiple access) or variations or derivatives, TDM (time division multiplexing) or variations or derivatives, or other cellular service standards. Wireless connectivity (or wireless interface)  2174  refers to wireless connectivity that is not cellular, and can include personal area networks (such as Bluetooth, Near Field, etc.), local area networks (such as Wi-Fi), and/or wide area networks (such as WiMax), or other wireless communication. 
     Peripheral connections  2180  include hardware interfaces and connectors, as well as software components (e.g., drivers, protocol stacks) to make peripheral connections. It will be understood that the computing device  2100  could both be a peripheral device (“to”  2182 ) to other computing devices, as well as have peripheral devices (“from”  2184 ) connected to it. The computing device  2100  commonly has a “docking” connector to connect to other computing devices for purposes such as managing (e.g., downloading and/or uploading, changing, synchronizing) content on computing device  2100 . Additionally, a docking connector can allow computing device  2100  to connect to certain peripherals that allow the computing device  2100  to control content output, for example, to audiovisual or other systems. 
     In addition to a proprietary docking connector or other proprietary connection hardware, the computing device  2100  can make peripheral connections  2180  via common or standards-based connectors. Common types can include a Universal Serial Bus (USB) connector (which can include any of a number of different hardware interfaces), DisplayPort including MiniDisplayPort (MDP), High Definition Multimedia Interface (HDMI), Firewire, or other types. 
     In some embodiments, the device  100  (e.g., comprising the MIM  100   a  and/or the MIM  100   b , as discussed with respect to  FIG.  1 A ) may be used as a high voltage capacitor and a low voltage capacitor in any appropriate component of the computing device  2100 . The device  100  may be formed, e.g., as discussed with respect to  FIGS.  2 A- 3   . In some embodiments, the device  100  may be used for any appropriate application of the computing device  2100 , e.g., where one or more capacitors may be used (e.g., may be used in the processor  2110 , in a memory of the memory subsystem  2160 , or in another component). 
     Reference in the specification to “an embodiment,” “one embodiment,” “some embodiments,” or “other embodiments” means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least some embodiments, but not necessarily all embodiments. The various appearances of “an embodiment,” “one embodiment,” or “some embodiments” are not necessarily all referring to the same embodiments. If the specification states a component, feature, structure, or characteristic “may,” “might,” or “could” be included, that particular component, feature, structure, or characteristic is not required to be included. If the specification or claim refers to “a” or “an” element, that does not mean there is only one of the elements. If the specification or claims refer to “an additional” element, that does not preclude there being more than one of the additional element. 
     Furthermore, the particular features, structures, functions, or characteristics may be combined in any suitable manner in one or more embodiments. For example, a first embodiment may be combined with a second embodiment anywhere the particular features, structures, functions, or characteristics associated with the two embodiments are not mutually exclusive 
     While the disclosure has been described in conjunction with specific embodiments thereof, many alternatives, modifications and variations of such embodiments will be apparent to those of ordinary skill in the art in light of the foregoing description. The embodiments of the disclosure are intended to embrace all such alternatives, modifications, and variations as to fall within the broad scope of the appended claims. 
     In addition, well known power/ground connections to integrated circuit (IC) chips and other components may or may not be shown within the presented figures, for simplicity of illustration and discussion, and so as not to obscure the disclosure. Further, arrangements may be shown in block diagram form in order to avoid obscuring the disclosure, and also in view of the fact that specifics with respect to implementation of such block diagram arrangements are highly dependent upon the platform within which the present disclosure is to be implemented (i.e., such specifics should be well within purview of one skilled in the art). Where specific details (e.g., circuits) are set forth in order to describe example embodiments of the disclosure, it should be apparent to one skilled in the art that the disclosure can be practiced without, or with variation of, these specific details. The description is thus to be regarded as illustrative instead of limiting. 
     The following examples pertain to further embodiments. Specifics in the examples may be used anywhere in one or more embodiments. All optional features of the apparatus described herein may also be implemented with respect to a method or process. 
     Example 1. An integrated circuit (IC) structure, comprising: a first stack comprising a lower, a middle, and an upper layer of conductive material with insulator layers therebetween, wherein a first of the insulator layers has a lower breakdown voltage than a second of the insulator layers; a second stack comprising at least the middle and upper layers of conductive material with one of the insulator layers therebetween; a first via comprising conductive material and over the first stack, wherein the first via is in contact with a pair of the lower, middle and upper layers that have the first of the insulator layers therebetween; and a second via comprising conductive material and over the second stack, wherein the second via extends through the upper layer and is in contact with the middle layer, the second via isolated from a sidewall of the upper layer by a spacer comprising a dielectric material. 
     Example 2. The IC structure of example 1 or any other example, wherein the first of the insulator layers is between the middle and upper layers. 
     Example 3. The IC structure of example 2 or any other example, wherein a breakdown voltage of the spacer exceeds the breakdown voltage of the second of the insulator layers between the middle and lower layers. 
     Example 4. The IC structure of example 3 or any other example, wherein a thickness of the second of the insulator layers is greater than a thickness of the first of the insulator layers. 
     Example 5. The IC structure of example 4 or any other example, wherein the first and the second of the insulator layers both comprise oxygen and silicon, or both comprise oxygen and a metal. 
     Example 6. The IC structure of example 1 or any other example, wherein: a portion of the first via extending through the upper layer has a first diameter; a portion of the second via extending through the upper layer has a second diameter; and the first diameter is at least twice the second diameter. 
     Example 7. The IC structure of example 1 or any other example, further comprising a third via comprising conductive material, wherein the third via is in contact with the upper layer but not the middle layer. 
     Example 8. The IC structure of example 7 or any other example, wherein: a portion of the first via extending through the upper layer has a first diameter; a portion of the second via extending through the upper layer has a second diameter; the first diameter is at least twice the second diameter; a portion of the third via intersecting the upper layer has a third diameter; and the second diameter is at least twice the third diameter. 
     Example 9. The IC structure of example 1 or any other example, wherein: a section of the upper layer in the first stack is isolated from another section of the upper layer in the second stack; a section of the middle layer in the first stack is isolated from another section of the middle layer in the second stack; a section of the first of the insulator layers in the first stack is isolated from another section of the first of the insulator layers in the second stack; and the second of the insulator layers is a continuous layer in the first and second stacks. 
     Example 10. The IC structure of example 1 or any other example, wherein: the spacer is between the sidewall of the upper layer and a portion of the second via that extends through the upper layer. 
     Example 11. The IC structure of any of examples 1-10 or any other example, wherein: the first of the insulator layers has a higher capacitance per unit area than the second of the insulator layers. 
     Example 12. The IC structure of any of examples 1-10 or any other example, wherein: the first stack comprises a first capacitor with a first terminal comprising the first via and a second terminal comprising the lower layer; the second stack comprises a second capacitor with a first terminal comprising the upper layer of the second stack and a second terminal comprising the middle layer of the second stack; a voltage rating of the first capacitor is higher than a voltage rating of the second capacitor; and a capacitance per unit area of the first capacitor is lower than a capacitance per unit area of the second capacitor. 
     Example 13. The IC structure of any of examples 1-10 or any other example, further comprising: a third stack separate from the first and second stacks, the third stack comprising the second of the insulator layers and another lower layer of conductive material; and a third via and a fourth via extending through the second of the insulator layers and in contact with the another lower layer. 
     Example 14. A system comprising: a memory to store instructions; and a processor coupled to the memory, the processor to execute the instructions, wherein one of the memory, the processor, or another component of the system comprises: a first stack comprising a lower, a middle, and an upper layer of conductive material with insulator layers therebetween, wherein a first of the insulator layers has a lower breakdown voltage than a second of the insulator layers; a second stack comprising at least the middle and upper layers of conductive material with one of the insulator layers therebetween; a first via comprising conductive material and over the first stack, wherein the first via is in contact with a pair of the lower, middle and upper layers that have the first of the insulator layers therebetween; and a second via comprising conductive material and over the second stack, wherein the second via extends through the upper layer and is in contact with the middle layer, the second via isolated from a sidewall of the upper layer. 
     Example 15. The system of example 14 or any other example, further comprising: a spacer between the sidewall of the upper layer and a portion of the second via that extends through the upper layer, the spacer comprising dielectric material. 
     Example 16. The system of example 14 or any other example, wherein a thickness of the second of the insulator layers is greater than a thickness of the first of the insulator layers. 
     Example 17. A method comprising: forming a first stack of lower, middle, and upper layers comprising conductive material with insulator layers therebetween; forming a second stack of the middle and upper layers of conductive material with one of the insulator layers therebetween; forming a hard mask layer over the first stack and the second stack, the hard mask layer comprising: a first opening over the first stack, and second and third openings over the second stack; forming, through the second opening, a spacer on a sidewall of the upper layer; forming a first via in the first opening, the first via in contact with two of the lower, middle, and upper layers of the first stack; and forming a second via in the second opening, the second via extending through the upper layer and in contact with the middle layer, the second via isolated from the sidewall of the upper layer by the spacer. 
     Example 18. The method of example 17 or any other example, wherein forming the hard mask layer comprises: forming an interlayer-dielectric (ILD) over the first stack and the second stack; and forming the hard mask layer over the ILD. 
     Example 19. The method of example 18 or any other example, wherein the hard mask layer is a first hard mask layer, and wherein forming the first via in the first opening comprises: conformally depositing a second hard mask layer over the first hard mask layer; selectively etching the second hard mask layer such that the ILD is exposed through the first opening, without the ILD being exposed through the second and third openings; selectively etching, through the first opening in the second hard mask layer, the ILD and the first stack to extend the first opening, without extending the second or third openings; and depositing conductive material in the first opening to form the first via. 
     Example 20. The method of example 18 or any other example, wherein forming the second via in the second opening comprises: conformally depositing a second hard mask layer over the first hard mask layer; selectively etching the second hard mask layer such that the ILD is exposed through the second opening, without the ILD being exposed through the third opening; selectively etching, through the second opening in the second hard mask layer, the ILD and the second stack to extend the second opening; and depositing conductive material in the second opening to form the second via, subsequent to forming the spacer. 
     Example 21. The method of example 18 or any other example, further comprising: depositing sacrificial material within the first opening and the second opening; conformally depositing a second hard mask layer over the first hard mask layer, subsequent to depositing the sacrificial material within the first and second openings; selectively etching the conformal hard mask layer such that the ILD is exposed through the third opening; selectively etching, through the third opening, the ILD to expose the upper layer; removing the sacrificial material; and depositing conductive material in the first opening to form the first via, in the second opening to form the second via, and in the third opening to form a third via. 
     Example 22. The method of any of examples 17-21 or any other example, further comprising: forming terminals of a first capacitor, such that a first terminal of the first capacitor is coupled to the first via, and a second terminal of the first capacitor is coupled to the lower layer; and forming terminals of a second capacitor, such that a first terminal of the second capacitor is coupled to the second via, and a second terminal of the second capacitor is coupled to a third via formed in the third opening. 
     Example 23. An apparatus comprising: means for performing the method of any of the examples 17-22 or any other example. 
     Example 24. An apparatus comprising: means for forming a first stack of lower, middle, and upper layers comprising conductive material with insulator layers therebetween; means for forming a second stack of the middle and upper layers of conductive material with one of the insulator layers therebetween; means for forming a hard mask layer over the first stack and the second stack, the hard mask layer comprising: a first opening over the first stack, and second and third openings over the second stack; means for forming, through the second opening, a spacer on a sidewall of the upper layer; means for forming a first via in the first opening, the first via in contact with two of the lower, middle, and upper layers of the first stack; and means for forming a second via in the second opening, the second via extending through the upper layer and in contact with the middle layer, the second via isolated from the sidewall of the upper layer by the spacer. 
     Example 25. The apparatus of example 24 or any other example, wherein the means for forming the hard mask layer comprises: means for forming an interlayer-dielectric (ILD) over the first stack and the second stack; and means for forming the hard mask layer over the ILD. 
     Example 26. The apparatus of example 25 or any other example, wherein the hard mask layer is a first hard mask layer, and wherein the means for forming the first via in the first opening comprises: means for conformally depositing a second hard mask layer over the first hard mask layer; means for selectively etching the second hard mask layer such that the ILD is exposed through the first opening, without the ILD being exposed through the second and third openings; means for selectively etching, through the first opening in the second hard mask layer, the ILD and the first stack to extend the first opening, without extending the second or third openings; and means for depositing conductive material in the first opening to form the first via. 
     Example 27. The apparatus of example 25 or any other example, wherein the means for forming the second via in the second opening comprises: means for conformally depositing a second hard mask layer over the first hard mask layer; means for selectively etching the second hard mask layer such that the ILD is exposed through the second opening, without the ILD being exposed through the third opening; means for selectively etching, through the second opening in the second hard mask layer, the ILD and the second stack to extend the second opening; and means for depositing conductive material in the second opening to form the second via, subsequent to forming the spacer. 
     Example 28. The apparatus of example 25 or any other example, further comprising: means for depositing sacrificial material within the first opening and the second opening; means for conformally depositing a second hard mask layer over the first hard mask layer, subsequent to depositing the sacrificial material within the first and second openings; means for selectively etching the conformal hard mask layer such that the ILD is exposed through the third opening; means for selectively etching, through the third opening, the ILD to expose the upper layer; means for removing the sacrificial material; and means for depositing conductive material in the first opening to form the first via, in the second opening to form the second via, and in the third opening to form a third via. 
     Example 29. The apparatus of any of examples 24-28 or any other example, further comprising: means for forming terminals of a first capacitor, such that a first terminal of the first capacitor is coupled to the first via, and a second terminal of the first capacitor is coupled to the lower layer; and means for forming terminals of a second capacitor, such that a first terminal of the second capacitor is coupled to the second via, and a second terminal of the second capacitor is coupled to a third via formed in the third opening. 
     An abstract is provided that will allow the reader to ascertain the nature and gist of the technical disclosure. The abstract is submitted with the understanding that it will not be used to limit the scope or meaning of the claims. The following claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate embodiment.