Patent Publication Number: US-10790263-B2

Title: Integrated circuit die having backside passive components and methods associated therewith

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a continuation of U.S. application Ser. No. 15/503,377, filed Feb. 10, 2017, entitled “INTEGRATED CIRCUIT DIE HAVING BACKSIDE PASSIVE COMPONENTS AND METHODS ASSOCIATED THEREWITH”, which is a national phase entry under 35 U.S.C. § 371 of International Application No. PCT/US2014/057807, filed Sep. 26, 2014, entitled “INTEGRATED CIRCUIT DIE HAVING BACKSIDE PASSIVE COMPONENTS AND METHODS ASSOCIATED THEREWITH,” which designates the United States of America, the entire disclosures of which are hereby incorporated by reference in its entirety and all purposes. 
    
    
     FIELD 
     Embodiments of the present disclosure generally relate to the field of integrated circuits, and more particularly, to apparatuses and methods associated with an integrated circuit die having backside passive components. 
     BACKGROUND 
     Input/output density of integrated circuit (IC) dies is continually increasing, while IC die sizes are continually decreasing. One of the concerns in IC die design is effective usage of IC die area; however, under the current state of the art, both passive and active components are disposed on a single side of a semiconductor substrate of the IC die due to signal breakout issues of placing components on different sides of the semiconductor substrate. 
     The background description provided herein is for the purpose of generally presenting the context of the disclosure. Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments will be readily understood by the following detailed description in conjunction with the accompanying drawings. To facilitate this description, like reference numerals designate like structural elements. Embodiments are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings. Unless clearly indicated otherwise, these drawings are not to scale. 
         FIG. 1  schematically illustrates a cross-section side view of an example integrated circuit (IC) assembly including an IC die having backside passive components disposed thereon, in accordance with various embodiments of the present disclosure. 
         FIG. 2  is an illustrative flow diagram of an integrated circuit (IC) die fabrication process in accordance with various embodiments of the present disclosure. 
         FIGS. 3-4  are illustrative cross-section views of selected operations illustrating stages in the IC die fabrication process of  FIG. 2 , in accordance with various embodiments of the present disclosure. 
         FIG. 5  is an illustrative flow diagram of an integrated circuit (IC) die fabrication process in accordance with various embodiments of the present disclosure. 
         FIGS. 6-7  are illustrative cross-section views of selected operations illustrating stages in the IC die fabrication process of  FIG. 5 , in accordance with various embodiments of the present disclosure. 
         FIG. 8  is an illustrative flow diagram of an integrated circuit (IC) die fabrication process in accordance with various embodiments of the present disclosure. 
         FIG. 9  is illustrative cross-section views of selected operations illustrating stages in the IC die fabrication process of  FIG. 8 , in accordance with various embodiments of the present disclosure. 
         FIG. 10  illustrates various cross-section views of an integrated circuit die, in accordance with various embodiments of the present disclosure. 
         FIG. 11  illustrates various cross-section views of an integrated circuit die, in accordance with various embodiments of the present disclosure. 
         FIG. 12  schematically illustrates a computing device that includes an integrated circuit die, in accordance with various embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure describe integrated circuit (IC) die configurations having backside passive components. In the following description, various aspects of the illustrative implementations will be described using terms commonly employed by those skilled in the art to convey the substance of their work to others skilled in the art. However, it will be apparent to those skilled in the art that embodiments of the present disclosure may be practiced with only some of the described aspects. For purposes of explanation, specific numbers, materials, and configurations are set forth in order to provide a thorough understanding of the illustrative implementations. However, it will be apparent to one skilled in the art that embodiments of the present disclosure may be practiced without the specific details. In other instances, well-known features are omitted or simplified in order not to obscure the illustrative implementations. 
     In the following detailed description, reference is made to the accompanying drawings that form a part hereof, wherein like numerals designate like parts throughout, and in which is shown by way of illustration embodiments in which the subject matter of the present disclosure may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of embodiments is defined by the appended claims and their equivalents. 
     For the purposes of the present disclosure, the phrase “A and/or B” means (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 description may use perspective-based descriptions such as top/bottom, in/out, over/under, and the like. Such descriptions are merely used to facilitate the discussion and are not intended to restrict the application of embodiments described herein to any particular orientation. 
     The description may use the phrases “in an embodiment,” or “in embodiments,” which may each refer to one or more of the same or different embodiments. Furthermore, the terms “comprising,” “including,” “having,” and the like, as used with respect to embodiments of the present disclosure, are synonymous. 
     The term “coupled with,” along with its derivatives, may be used herein. “Coupled” may mean one or more of the following. “Coupled” may mean that two or more elements are in direct physical or electrical contact. However, “coupled” may also mean that two or more elements indirectly contact each other, but yet still cooperate or interact with each other, and may mean that one or more other elements are coupled or connected between the elements that are said to be coupled with each other. The term “directly coupled” may mean that two or more elements are in direct contact. 
     In various embodiments, the phrase “a first feature formed, deposited, or otherwise disposed on a second feature,” may mean that the first feature is formed, deposited, or disposed over the second feature, and at least a part of the first feature may be in direct contact (e.g., direct physical and/or electrical contact) or indirect contact (e.g., having one or more other features between the first feature and the second feature) with at least a part of the second feature. 
     As used herein, the term “module” may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC), an electronic circuit, a system-on-chip (SoC), a processor (shared, dedicated, or group), and/or memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality. 
       FIG. 1  schematically illustrates a cross-section side view of an example integrated circuit (IC) assembly  100 . In embodiments, the IC assembly  100  may include one or more dies (e.g., die  106 ) electrically and/or physically coupled with a package substrate  116 , as can be seen. The package substrate  116  may further be electrically coupled with a circuit board  124 , as can be seen. 
     In embodiments, die  106  may include a semiconductor substrate  126 . Semiconductor substrate  126  may comprise any suitable material (e.g., silicon). Die  106  may also include a plurality of active components disposed on a first side of the substrate, hereinafter referred to as an active side of the substrate due to the location of the active components. Such active components are depicted here by active component layer  128  representing a plurality of active components. Active components may include any component capable of controlling an electrical signal (e.g., transistors). In embodiments, die  106  may also include a plurality of passive components (e.g., metal-insulator-metal (MIM) capacitor  130 ) disposed on a second side of semiconductor substrate  126 , hereinafter referred to as the backside of semiconductor substrate  126 . As depicted, the backside of semiconductor substrate  126  may be disposed opposite the active side of semiconductor substrate  126 , such that the plurality of active components may be disposed on a side opposite the plurality of passive components. Such a configuration may enable utilization of space that may have previously been unused on semiconductor substrate  126 . As a result, such a configuration may enable higher input/output densities for a similarly configured IC die. 
     In some embodiments, die  106  may include a plurality of through-substrate vias (TSVs) (e.g., TSVs  132   a  and  132   b , hereinafter collectively referred to as TSVs  132 ) disposed in the semiconductor substrate. The TSVs may be configured to route electrical signals between the active side of semiconductor substrate  126  and the backside of semiconductor substrate  126 . As a result, TSVs  132  may enable one or more of the plurality of passive components to be electrically coupled with the active side of semiconductor substrate  126 . In embodiments, one or more layers of electrically insulative material (e.g., layers  134 ) may be disposed on the active side of the semiconductor substrate. The one or more layers of electrically insulative material may, as depicted, encapsulate the plurality of active components. In embodiments, the one or more layers of electrically insulative material may include electrical routing features (e.g., electrical routing feature  136 ) disposed therein. In addition, a plurality of die interconnect structures (e.g., die interconnect structure  108 ) may be disposed in the one or more layers of the electrically insulative material. In embodiments, the electrical routing features may be configured to electrically couple the die interconnect structures with the plurality of active components and/or the plurality of TSVs. As discussed further below, the die interconnect structures may be configured to electrically couple die  106  with package substrate  116 . 
     In embodiments, one or more redistribution layers (RDLs) (e.g., RDL  140 ) may be disposed on the backside of semiconductor substrate  126 . The one or more RDLs may include one or more layers of electrically insulative material (e.g., layer  142 ) disposed on the backside of the semiconductor substrate. As depicted, the one or more layers of electrically insulative material disposed on the backside of semiconductor substrate  126  may encapsulate the plurality of passive components. The one or more RDLs may also include a plurality of interconnect structures (e.g., landing pad  144 ) disposed in the one or more layers of the electrically insulative material. The one or more RDLs may also include electrical routing features (e.g., via  146 ) disposed in the one or more second layers of electrically insulative material. In embodiments, the electrical routing features may be configured to electrically couple the plurality of interconnect structures with the plurality of passive components. 
     Die  106  may be attached to package substrate  116  according to a variety of suitable configurations, including a flip-chip configuration, as depicted, or other configurations such as, for example, being embedded in the package substrate  116  or being configured in a wirebonding arrangement. In the flip-chip configuration, the die  106  may be attached to a surface of the package substrate  116  via die interconnect structures  108  such as bumps, pillars, or other suitable structures that may also electrically couple die  106  with the package substrate  116 . 
     Die  106  may represent a discrete chip made from a semiconductor material and may be, include, or be a part of a processor, memory, or ASIC in some embodiments. In some embodiments, an electrically insulative material such as, for example, molding compound or underfill material (not pictured) may partially encapsulate a portion of die  106  and/or interconnect structures  108 . Die interconnect structures  108  may be configured to route the electrical signals between die  106  and package substrate  116 . 
     Package substrate  116  may include electrical routing features configured to route electrical signals to or from die  106 . The electrical routing features may include, for example, traces disposed on one or more surfaces of package substrate  116  and/or internal routing features such as, for example, trenches, vias, or other interconnect structures to route electrical signals through package substrate  116 . For example, in some embodiments, package substrate  116  may include electrical routing features (such as die bond pads  110 ) configured to receive the die interconnect structures  108  and route electrical signals between die  106  and package substrate  116 . In some embodiments, the package substrate  116  is an epoxy-based laminate substrate having a core and/or build-up layers such as, for example, an Ajinomoto Build-up Film (ABF) substrate. 
     The circuit board  124  may be a printed circuit board (PCB) composed of an electrically insulative material such as an epoxy laminate. For example, the circuit board  116  may include electrically insulating layers composed of materials such as, for example, polytetrafluoroethylene, phenolic cotton paper materials such as Flame Retardant 4 (FR-4), FR-1, cotton paper and epoxy materials such as CEM-1 or CEM-3, or woven glass materials that are laminated together using an epoxy resin prepreg material. Structures (not shown), for example, vias, may be formed through the electrically insulating layers to route the electrical signals of the die  106  through the circuit board  124 . The circuit board  124  may be composed of other suitable materials in other embodiments. In some embodiments, the circuit board  124  is a motherboard (e.g., motherboard  1202  of  FIG. 12 ). 
     Package-level interconnects such as, for example, solder balls  120  or land-grid array (LGA) structures may be coupled to one or more lands (hereinafter “lands  118 ”) on the package substrate  116  and one or more pads  122  on the circuit board  124  to form corresponding solder joints that are configured to further route the electrical signals between the package substrate  116  and the circuit board  124 . Other suitable techniques to physically and/or electrically couple the package substrate  116  with the circuit board  124  may be used in other embodiments. 
       FIG. 2  is an illustrative flow diagram of an integrated circuit (IC) die fabrication process for forming backside metal-insulator-metal (MIM) capacitors in accordance with some embodiments of the present disclosure.  FIGS. 3-4  provide cross-section views of selected operations illustrating stages in the IC die fabrication process  200 , in accordance with various embodiments. As a result,  FIGS. 2-4  will be described in conjunction with one another. To aid in this description, the operations performed in  FIG. 2  are referenced on the arrows moving from operation to operation in  FIGS. 3-4 . Furthermore, to enable more detailed views of the IC die fabrication, only a portion of an IC die is depicted in each procedure. In addition, not all reference numbers may be depicted in each operation in  FIGS. 3-4 . 
     The process may begin at block  202 , where a semiconductor substrate  301  may be provided. In some embodiments, as depicted, the semiconductor substrate may be provided in the form of an IC die assembly (e.g., IC die assembly  300 ). IC die assembly may have an electrically insulative layer  302 , such as a passivation layer, disposed on a backside of semiconductor substrate  301 . Electrically insulative layer  302  may comprise any suitable material, including silicon nitride (SiN) or silicon carbide (SiC), for example. IC die assembly  300  may also include a plurality of active components (e.g., those depicted by layer  304 ) disposed on an active side of semiconductor substrate  301 . In some embodiments, IC die assembly  300  may include a plurality of through-substrate vias (TSVs) (e.g., TSVs  306   a  and  306   b , hereinafter collectively referred to as TSVs  306 ) disposed in semiconductor substrate  301 . The TSVs may be configured to route electrical signals between the active side of semiconductor substrate  301  and the backside of semiconductor substrate  301 . In embodiments, one or more layers of electrically insulative material (e.g., layers  307 ) may be disposed on the active side of the semiconductor substrate  301 . The one or more layers of electrically insulative material may, as depicted, encapsulate the plurality of active components. In embodiments, the one or more layers of electrically insulative material may include electrical routing features disposed therein. In addition, a plurality of die interconnect structures (e.g., die interconnect structure  308 ) may be disposed in the one or more layers of the electrically insulative material. In embodiments, the electrical routing features may be configured to electrically couple the die interconnect structures with the plurality of active components and/or the plurality of TSVs. In some embodiments, IC die assembly  300  may be provided with a carrier wafer  312  attached by way of an adhesive  310  (e.g., glue). In other embodiments, semiconductor substrate  301  may be provided with fewer or without any of the above described aspects of IC die assembly  300  and the above described portions of IC die assembly  300  may be formed on semiconductor substrate  301  in conjunction with the procedures depicted by the remainder of  FIGS. 2-4 . To facilitate the description of each process, the remaining procedures will only depict the backside portion of IC die assembly  300  represented here by the area of IC die assembly encompassed by section  314 . 
     Once semiconductor substrate  301  has been provided, the process may proceed to block  204 , where fabrication of an MIM capacitor may begin through deposition of first metal layer  318  on the backside of semiconductor substrate  301 . First metal layer  318  may be referred to as a capacitor bottom electrode and may comprise tantalum, tantalum nitride, titanium, titanium nitride, or any other suitable materials. In embodiments, as depicted, the first metal layer may be formed over one or more of the TSVs (e.g., TSV  306   b ) disposed in semiconductor substrate  301 . In other embodiments, such as that depicted in  FIG. 10 , semiconductor substrate  301  may not be formed over any TSVs. Such embodiments are discussed in greater detail in reference to  FIG. 10 , below. 
     At block  206 , a photoresist layer  320  may be formed from photoresist material on one or more portions of first metal layer  318 . Such a layer may be formed by applying the photoresist material, patterning the photoresist material by exposing the photoresist material to an ultraviolet light source or a laser, and developing the photoresist material that was not exposed to the ultraviolet light source or the laser through application of an appropriate solvent. While only a single portion of photoresist material is depicted, it will be appreciated that photoresist layer  320  may include any number of portions of photoresist material at locations on the first metal layer where the first metal layer is to be preserved (e.g., any location where a capacitor bottom electrode is desired). 
     At block  208 , the portion of first metal layer  318  that is not covered by photoresist layer  320  may be removed. This may be accomplished through any suitable dry or wet etch process. At block  210 , photoresist layer  320  may be removed and any remaining residues may be cleaned off the surface of first metal layer  318 . 
     At block  212 , a dielectric layer  322  may be formed on a surface of first metal layer  318  and a second metal layer  324  may be formed on a surface of dielectric layer  322 . Dielectric layer  322  may be referred to as a capacitor dielectric and as such may be composed of any suitable capacitor dielectric material, including, but not limited to, aluminum oxide (Al 2 O 3 ), aluminum nitride (AlN), silicon dioxide (SiO 2 ), silicon nitride (Si 3 N 4 ), tantalum oxide (Ta 2 O 5 ), titanium oxide (TiO 2 ), or hafnium oxide (HfO 2 ), or any combinations thereof. Second metal layer  324  may be referred to as a capacitor top electrode and may comprise any suitable material, including, but not limited to, tantalum, tantalum nitride, titanium, titanium nitride, or any other suitable materials. It will be appreciated that the thickness of dielectric layer  322  and/or second metal layer  324  may be adjusted to achieve any desired electrical characteristics of the resulting MIM capacitor. 
     At block  214 , another photoresist layer  326  may be formed from photoresist material on one or more portions of second metal layer  324 . This may be accomplished in a similar manner to that described above in reference to block  206 . While only a single portion of photoresist material is depicted, it will be appreciated that photoresist layer  326  may include any number of portions of photoresist material at locations on the second metal layer  324  where the second metal layer  324  and the underlying dielectric layer  322  are to be preserved (e.g., any location where a capacitor top electrode is desired). 
     At block  216 , the portion of second metal layer  324  and dielectric layer  322  not covered by photoresist layer  326  may be removed. This may be accomplished through any suitable dry or wet etch process. At block  218 , photoresist layer  326  may be removed to reveal second metal layer  324 . First metal layer  318 , dielectric layer  322 , and second metal layer  324  may combine to form the MIM capacitor. 
     At block  220 , an electrically insulative layer  328  may be deposited over the MIM capacitor. Electrically insulative layer  328  may comprise any suitable material, including, but not limited to, silicon nitride (SiN) or silicon carbide (SiC). Electrically insulative material may, in some embodiments, form a hermetic barrier that may protect first metal layer  318  and second metal layer  324  from oxidation and from trace metal and moisture contamination. Such a layer may also be referred to as a passivation layer. 
     At block  222 , yet another photoresist layer  330  may be formed over electrically insulative layer  328 . As depicted a number of openings may also be formed in photoresist layer  330  to expose corresponding locations of electrically insulative layer  328  to be removed. Photoresist layer  330  may be formed in a similar manner to that described in reference to block  206 , above. The openings in the photoresist layer may be formed at locations where electrical connections between the first metal layer  318 , the second metal layer  324 , or one or more of the TSVs may be desired. 
     At block  224 , via holes  332   a - c  may be formed in electrically insulative layer  328 . Via holes  332   a - c  may be formed through any suitable process, such as, for example, a plasma etch process using the patterned photoresist material. At block  226 , photoresist layer  330  may be removed and any remaining residues may be cleaned off the surface of electrically insulative layer  328 . 
     At block  228  redistribution layer (RDL)  342  may be formed. In an embodiment, RDL  342  may be formed by first disposing an RDL barrier (e.g., RDL barrier  334 ) and a copper seed layer onto the backside surface and into via holes  332   a - c . A photoresist material may then be applied and openings formed in the photoresist over the via holes  332   a - c  and at those locations where backside electrical routing features  336  are desired. Backside electrical routing features  336  may include wire traces for distributing electrical signals from one location to another, and landing pads for creating electrical connections to another die (described in reference to  FIGS. 10-11  below). The backside electrical routing features  336  may provide for signal breakout of the passive components (e.g., the MIM capacitor formed above) or signal breakout to one of the TSVs (e.g., TSV  306   a ) disposed in semiconductor substrate  301 . Next, a metallic material such as copper or gold may be disposed inside the resist openings using an electroplating technique, filling via holes  332   a - c  to metalize the vias and forming backside electrical routing features  336  simultaneously. The photoresist material may then be removed, and the copper seed layer and RDL barrier material in between the backside electrical routing features  336  may be removed using wet or dry etch processes. The backside electrical routing features  336  may have a passivation layer  338  formed thereon. The passivation layer may protect the landing pads from oxidation and from trace metal and moisture contamination. In embodiments, passivation layer  338  may have openings at the locations of the landing pads that may have a surface finish  340  formed therein. In embodiments, the surface finish may be a solder compatible surface finish. Suitable surface finishes include, but are not limited to: electroless cobalt phosphide (CoP)/immersion gold (Au); electroless cobalt tungsten phosphide (CoWP)/immersion Au; electroless nickel phosphide (NiP)/immersion Au; electroless NiP/electroless palladium (Pd)/immersion Au; electroless tin (Sn); electroless NiP/electroless Sn; electroless CoWP/electroless Sn; electroless copper (Cu)/electroless CoP/immersion Au; electroless Cu/electroless CoWP/immersion Au; electroless Cu/electroless; NiP/immersion Au; electroless Cu/electroless NiP/electroless Pd/immersion Au; electroless Cu/electroless Sn; electroless Cu/electroless NiP/electroless Sn; electroless Cu/electroless CoP/immersion Au; electroless Cu/electroless CoWP/electroless Sn. It will be appreciated that other surface finishes may also be suitable depending on chip-to-chip solder material(s) and/or chip-to-chip attachment methods that may be employed. In some embodiments, a die interconnect structure (e.g., bump) may be formed on top of, in addition to, or instead of the surface finish on top of one or more of the landing pads. The die interconnect structure (e.g., bump) may be formed from, for example, lead-tin (PbSn), Sn, tin-silver (SnAg), copper (Cu), indium (In), SnAgCu, SnCu, Au, etc. After block  228 , the IC die may be detached from the temporary carrier wafer using any suitable, available wafer de-bonding equipment and processing. In other embodiments, the RDL  342  may include backside electrical routing features  336  consisting of a metallic material such as aluminum which are formed using a conventional subtractive etch-type process sequence. 
       FIG. 5  is an illustrative flow diagram of an integrated circuit (IC) die fabrication process in accordance with some embodiments of the present disclosure.  FIGS. 6-7  provide cross-section views of selected operations illustrating stages in the IC die fabrication process  500 , in accordance with an illustrative embodiment. As a result,  FIGS. 5-7  will be described in conjunction with one another. To aid in this description, the operations performed in  FIG. 5  are referenced on the arrows moving from operation to operation in  FIGS. 6-7 . Furthermore, to enable more detailed views of the IC die fabrication, only a portion of an IC die is depicted in each procedure. In addition, not all reference numbers may be depicted in each operation in  FIGS. 6-7 . 
     The process may begin at block  502 , where a semiconductor substrate  602  may be provided. In some embodiments, the semiconductor substrate may be provided in the form of an IC die assembly (e.g., IC die assembly  300  of  FIG. 3  discussed at length above). The process may then proceed to block  504  where a photoresist layer  608  may be formed on electrically insulative layer  604 . Such a layer may be formed by applying photoresist material, patterning the photoresist material by exposing the photoresist material to an ultraviolet light source or a laser, and developing the photoresist material that was not exposed to the ultraviolet light source or the laser through application of an appropriate solvent. This patterning may result in the photoresist layer  608  having openings  610   a - 610   c  formed therein at locations where trenches are to be formed in semiconductor substrate  602 . 
     At block  506 , trenches  612   a - c  may be formed in semiconductor substrate  602 . These trenches may be formed through an etching process, such as a plasma etch process. It will be appreciated that, while the cross-section of the trenches may be rectangular, when viewed from the top down, the trenches may be in the shape of a square, rectangle, circle, oval, etc. At block  508 , the photoresist material may be removed, along with any residue that may have remained on the surface of electrically insulative layer  604 . 
     At block  510 , a trench liner  614  may be formed. Trench liner  614  may be, or include, any suitable electrically insulative material (e.g., silicon dioxide (SiO 2 )). In addition, a first metal layer  618  may be deposited on the backside of semiconductor substrate  602 . First metal layer  618  may be referred to as a capacitor bottom electrode and may comprise tantalum, tantalum nitride, titanium, titanium nitride, or any other suitable materials. In embodiments, as depicted, the first metal layer  618  may be formed over one or more of the TSVs (e.g. TSV  606   b ) disposed in semiconductor substrate  602 . In other embodiments, such as that depicted in  FIG. 10 , first metal layer  618  may not be formed over any TSVs. Such embodiments are discussed in greater detail in reference to  FIG. 10 , below. 
     At block  512 , a photoresist layer  620  may be formed, as discussed above in reference to block  504 , on one or more portions of first metal layer  618 . At block  514 , the portion of first metal layer  618  that is not covered by photoresist layer  620  may be removed. This may be accomplished through any suitable dry or wet etch process. At block  516 , photoresist layer  620  may be removed and any remaining residues may be cleaned off the surface of first metal layer  618 . 
     At block  518 , a dielectric layer  622  may be formed on a surface of first metal layer  618  and a second metal layer  624  may be formed on a surface of dielectric layer  622 . Dielectric layer  622  may be referred to as a capacitor dielectric and as such may be composed of any suitable capacitor dielectric material, including, but not limited to aluminum oxide (Al 2 O 3 ), aluminum nitride (AlN), silicon dioxide (SiO 2 ), silicon nitride (Si 3 N 4 ), tantalum oxide (Ta 2 O 5 ), titanium oxide (TiO 2 ), or hafnium oxide (HfO 2 ), or any combinations thereof. Second metal layer  624  may be referred to as a capacitor top electrode and may comprise any suitable material, including, but not limited to, tantalum, tantalum nitride, titanium, titanium nitride, or any other suitable materials. It will be appreciated that the thickness of dielectric layer  622  and/or second metal layer  624  may be adjusted to achieve any desired electrical characteristics of the resulting trench capacitor. 
     At block  520 , another photoresist layer  626  may be formed from photoresist material on one or more portions of second metal layer  624 . This may be accomplished in a similar manner to that described above in reference to block  504 . While only a single portion of photoresist material is depicted, it will be appreciated that photoresist layer  626  may include any number of portions of photoresist material at locations on the second metal layer  624  where the second metal layer  624  and the underlying dielectric layer  622  are to be preserved (e.g., any location where a capacitor top electrode is desired). 
     At block  522 , the portion of second metal layer  624  and dielectric layer  622  not covered by photoresist layer  626  may be removed. This may be accomplished through any suitable dry or wet etch process. At block  524 , photoresist layer  626  may be removed to reveal second metal layer  624 . First metal layer  618 , dielectric layer  622 , and second metal layer  624  may combine to form a trench capacitor. 
     At block  526 , an electrically insulative layer  628  may be deposited over the trench capacitor. Electrically insulative layer  628  may comprise any suitable material, including, but not limited to, silicon nitride (SiN) or silicon carbide (SiC). Electrically insulative material may, in some embodiments, form a hermetic barrier that may protect first metal layer  618  and second metal layer  624  from oxidation and from trace metal and moisture contamination. Such an electrically insulative layer may be referred to as a passivation layer. 
     At block  528 , yet another photoresist layer  630  may be formed over electrically insulative layer  628 . As depicted a number of openings may also be formed in photoresist layer  630  to expose corresponding locations of electrically insulative layer  628  to be removed. Photoresist layer  630  may be formed in a similar manner to that described in reference to block  504 , above. The openings in the photoresist layer may be formed at locations where electrical connections between the first metal layer  618 , the second metal layer  624 , and/or one or more of the TSVs may be desired. 
     At block  530 , via holes  632   a - c  may be formed in electrically insulative layer  628 . Via holes  632   a - c  may be formed through any suitable process, such as, for example, a plasma etch process using the patterned photoresist material. At block  532 , photoresist layer  630  may be removed and any remaining residues may be cleaned off the surface of electrically insulative layer  628 . 
     At block  534  redistribution layer (RDL)  642  may be formed. In an embodiment, RDL  642  may be formed by first disposing an RDL barrier (e.g., RDL barrier  634 ) and a copper seed layer onto the backside surface and into via holes  632   a - c . A photoresist material may then be applied and openings formed in the photoresist over the via holes  632   a - c  and at those locations where backside electrical routing features  636  are desired. Backside electrical routing features  636  may include wire traces for distributing electrical signals from one location to another, and landing pads for creating electrical connections to another die (described in reference to  FIGS. 10-11  below). The backside electrical routing features  636  may provide for signal breakout of the passive components (e.g., the trench capacitor formed above) or signal breakout to one of the TSVs (e.g., TSV  606   a ) disposed in semiconductor substrate  602 . Next, a metallic material such as copper or gold may be disposed inside the resist openings using an electroplating technique, filling via holes  632   a - c  to metalize the vias and forming backside electrical routing features  636  simultaneously. The photoresist material may then be removed, and the copper seed layer and RDL barrier material in between the backside electrical routing features  636  may be removed using wet or dry etch processes. The backside electrical routing features  636  may have a passivation layer  638  formed thereon. The passivation layer may protect the landing pads from oxidation and from trace metal and moisture contamination. In embodiments, passivation layer  638  may have openings at the locations of the landing pads that may have a surface finish  640  formed therein. In embodiments, the surface finish may be a solder compatible surface finish. Suitable surface finishes include, but are not limited to: electroless cobalt phosphide (CoP)/immersion gold (Au); electroless cobalt tungsten phosphide (CoWP)/immersion Au; electroless nickel phosphide (NiP)/immersion Au; electroless NiP/electroless palladium (Pd)/immersion Au; electroless tin (Sn); electroless NiP/electroless Sn; electroless CoWP/electroless Sn; electroless copper (Cu)/electroless CoP/immersion Au; electroless Cu/electroless CoWP/immersion Au; electroless Cu/electroless; NiP/immersion Au; electroless Cu/electroless NiP/electroless Pd/immersion Au; electroless Cu/electroless Sn; electroless Cu/electroless NiP/electroless Sn; electroless Cu/electroless CoP/immersion Au; electroless Cu/electroless CoWP/electroless Sn. It will be appreciated that other surface finishes may also be suitable depending on chip-to-chip solder material(s) and/or chip-to-chip attachment methods that may be employed. In some embodiments, a die interconnect structure (e.g., bump) may be formed on top of, in addition to, or instead of the surface finish on top of one or more of the landing pads. The die interconnect structure (e.g., bump) may be formed from, for example, lead-tin (PbSn), Sn, tin-silver (SnAg), copper (Cu), indium (In), SnAgCu, SnCu, Au, etc. After block  534 , the IC die may be detached from the temporary carrier wafer using any suitable, available wafer de-bonding equipment and processing. In other embodiments, the RDL  642  may include backside electrical routing features  636  consisting of a metallic material such as aluminum which are formed using a conventional subtractive etch-type process sequence. 
       FIG. 8  is an illustrative flow diagram of an integrated circuit (IC) die fabrication process in accordance with some embodiments of the present disclosure.  FIG. 9  provides cross-section views of selected operations illustrating stages in the IC die fabrication process  800 , in accordance with an illustrative embodiment. As a result,  FIGS. 8 and 9  will be described in conjunction with one another. To aid in this description, the operations performed in  FIG. 8  are referenced on the arrows moving from operation to operation in  FIG. 9 . Furthermore, to enable more detailed views of the IC die fabrication, only a portion of a die is depicted in each procedure. In addition, not all reference numbers may be depicted in each operation in  FIG. 9 . 
     The process may begin at block  802 , where a semiconductor substrate  901  may be provided. In some embodiments, the semiconductor substrate may be provided in the form of an IC die assembly (e.g., IC die assembly  300  of  FIG. 3  discussed at length above). The process may then proceed to block  804 , where a thin film resistor layer  918  may be deposited on the backside of semiconductor substrate  901 . Thin film resistor layer  918  may comprise tantalum, tantalum nitride, titanium, nickel chromium (NiCr), or any other suitable materials. In embodiments, as depicted, the thin film resistor layer  918  may be formed over one or more of the TSVs (e.g. TSV  906   b ) disposed in semiconductor substrate  901 . In other embodiments, such as that depicted in  FIG. 10 , the semiconductor substrate  901  may not be formed over any TSVs. Such embodiments are discussed in greater detail in reference to  FIG. 10 , below. 
     At block  806 , a photoresist layer  920  may be formed from photoresist material on one or more portions of thin film resistor layer  918 . Such a layer may be formed by applying the photoresist material, patterning the photoresist material by exposing the photoresist material to an ultraviolet light source or a laser, and developing the photoresist material that was not exposed to the ultraviolet light source or the laser through application of an appropriate solvent. While only a single portion of photoresist material is depicted, it will be appreciated that photoresist layer  920  may include any number of portions of photoresist material at locations on the thin film resistor layer where the thin film resistor layer is to be preserved (e.g., any location where a resistor is desired). 
     At block  808 , the portion of thin film resistor layer  918  that is not covered by photoresist layer  920  may be removed. This may be accomplished through any suitable dry or wet etch process. At block  810 , photoresist layer  920  may be removed and any remaining residues may be cleaned off the surface of thin film resistor layer  918 . 
     At block  812 , an electrically insulative layer  928  may be deposited over the thin film resistor layer  918 . Electrically insulative layer  928  may comprise any suitable material, including, but not limited to, silicon nitride (SiN) or silicon carbide (SiC). Electrically insulative material may, in some embodiments, form a hermetic barrier that may protect thin film resistor layer  918  from oxidation and from trace metal and moisture contamination. Such an electrically insulative layer may be referred to as a passivation layer. 
     At block  814 , yet another photoresist layer  930  may be formed over electrically insulative layer  928 . As depicted a number of openings may also be formed in photoresist layer  930  to expose corresponding locations of electrically insulative layer  928  to be removed. Photoresist layer  930  may be formed in a similar manner to that described in reference to block  804 , above. The openings in the photoresist layer  930  may be formed at locations where electrical connections between the thin film resistor layer  918  and/or one or more of the TSVs may be desired. 
     At block  816 , via holes  932   a - c  may be formed in electrically insulative layer  928 . Via holes  932   a - c  may be formed through any suitable process, such as, for example, a plasma etch process using the patterned photoresist material. At block  818 , photoresist layer  930  may be removed and any remaining residues may be cleaned off the surface of electrically insulative layer  928 . 
     At block  820 . redistribution layer (RDL)  942  may be formed. In an embodiment, RDL  942  may be formed by first disposing an RDL barrier (e.g., RDL barrier  934 ) and a copper seed layer onto the backside surface and into via holes  932   a - c . A photoresist material may then be applied and openings formed in the photoresist over the via holes  932   a - c  and at those locations where backside electrical routing features  936  are desired. Backside electrical routing features  936  may include wire traces for distributing electrical signals from one location to another, and landing pads for creating electrical connections to another die (described in reference to  FIGS. 10-11  below). The backside electrical routing features  936  may provide for signal breakout of the passive components (e.g., the resistor formed by thin film resistor layer  918 ) or signal breakout to one of the TSVs (e.g., TSV  906   a ) disposed in semiconductor substrate  901 . Next, a metallic material such as copper or gold may be disposed inside the resist openings using an electroplating technique, filling via holes  932   a - c  to metalize the vias and forming backside electrical routing features  936  simultaneously. The photoresist material may then be removed, and the copper seed layer and RDL barrier material in between the backside electrical routing features  936  may be removed using wet or dry etch processes. The backside electrical routing features  936  may have a passivation layer  938  formed thereon. The passivation layer may protect the landing pads from oxidation and from trace metal and moisture contamination. In embodiments, passivation layer  938  may have openings at the locations of the landing pads that may have a surface finish  940  formed therein. In embodiments, the surface finish may be a solder compatible surface finish. Suitable surface finishes include, but are not limited to: electroless cobalt phosphide (CoP)/immersion gold (Au); electroless cobalt tungsten phosphide (CoWP)/immersion Au; electroless nickel phosphide (NiP)/immersion Au; electroless NiP/electroless palladium (Pd)/immersion Au; electroless tin (Sn); electroless NiP/electroless Sn; electroless CoWP/electroless Sn; electroless copper (Cu)/electroless CoP/immersion Au; electroless Cu/electroless CoWP/immersion Au; electroless Cu/electroless; NiP/immersion Au; electroless Cu/electroless NiP/electroless Pd/immersion Au; electroless Cu/electroless Sn; electroless Cu/electroless NiP/electroless Sn; electroless Cu/electroless CoP/immersion Au; electroless Cu/electroless CoWP/electroless Sn. It will be appreciated that other surface finishes may also be suitable depending on chip-to-chip solder material(s) and/or chip-to-chip attachment methods that may be employed. In some embodiments, a die interconnect structure (e.g., bump) may be formed on top of, in addition to, or instead of the surface finish on top of one or more of the landing pads. The die interconnect structure (e.g., bump) may be formed from, for example, lead-tin (PbSn), Sn, tin-silver (SnAg), copper (Cu), indium (In), SnAgCu, SnCu, Au, etc. After block  820 , the IC die may be detached from the temporary carrier wafer using any suitable, available wafer de-bonding equipment and processing. In other embodiments, the RDL  942  may include backside electrical routing features  936  consisting of a metallic material such as aluminum which are formed using a conventional subtractive etch-type process sequence. 
       FIG. 10  illustrates various cross-section views of an integrated circuit die, in accordance with various embodiments of the present disclosure. In the first embodiment, IC die  1000  is depicted. IC die  1000  may include semiconductor substrate  1008 . IC die  1000  may have an electrically insulative layer  1018  disposed on a backside of semiconductor substrate  1008 . Electrically insulative layer  1018  may comprise any suitable material including, silicon nitride (SiN) or silicon carbide (SiC), for example. IC die  1000  may also include a plurality of active components (e.g., those depicted by layer  1012 ) disposed on an active side of semiconductor substrate  1008 . In embodiments, one or more layers of electrically insulative material (e.g., layers  1014 ) may be disposed on the active side of the semiconductor substrate  1008 . The one or more layers of electrically insulative material may, as depicted, encapsulate the plurality of active components. In embodiments, the one or more layers of electrically insulative material may include electrical routing features disposed therein. In addition, a plurality of die interconnect structures (e.g., die interconnect structure  1016 ) may be disposed in the one or more layers of the electrically insulative material. In embodiments, the electrical routing features may be configured to electrically couple the die interconnect structures with the plurality of active components. In some embodiments, IC die  1000  may have a metal-insulator-metal (MIM) capacitor  1028  formed thereon. MIM capacitor  1028  may be formed as discussed above in reference to  FIGS. 2-4 . The MIM capacitor  1028  may have electrical connections formed at  1020  and  1022  on terminals of first and second metal layer, respectively, with first and second interconnect structures, respectively disposed in one or more backside redistribution layers (RDLs)  1030 . Electrical connections may be configured to route electrical signals between a second die  1026  and MIM capacitor  1028  by way of die interconnect structures  1024   a  and  1024   b.    
     IC die  1002  depicts a similar configuration to that of IC die  1000 ; however, MIM capacitor  1028  has been replaced with trench capacitor  1032 . Such a trench capacitor may be formed as described above in reference to  FIGS. 5-7 . IC die  1004 , again, depicts a similar configuration to that of IC die  1000 ; however, MIM capacitor  1028  has been replaced with thin film resistor  1034 . Such a thin film resistor may be formed as described above in reference to  FIGS. 8 and 9 . 
       FIG. 11  illustrates various cross-section views of an integrated circuit die, in accordance with various embodiments of the present disclosure. In the first embodiment, IC die  1100  is depicted. IC die  1100  may include semiconductor substrate  1108 . In some embodiments, IC die  1100  may include a plurality of through-substrate vias (TSVs) (e.g., TSVs  1109   a  and  1109   b ) disposed in semiconductor substrate  1108 . The TSVs may be configured to route electrical signals between an active side of semiconductor substrate  1108 , depicted here as the bottom of semiconductor substrate  1108  and the backside of semiconductor substrate, depicted here as the top of semiconductor substrate  1108 . IC die  1100  may have an electrically insulative layer  1118  disposed on a backside of semiconductor substrate  1108 . Electrically insulative layer  1118  may comprise any suitable material including silicon nitride (SiN) or silicon carbide (SiC), for example. IC die  1100  may also include a plurality of active components (e.g., those depicted by layer  1112 ) disposed on an active side of semiconductor substrate  1108 . In embodiments, one or more layers of electrically insulative material (e.g., layers  1114 ) may be disposed on the active side of the semiconductor substrate  1108 . The one or more layers of electrically insulative material may, as depicted, encapsulate the plurality of active components. In embodiments, the one or more layers of electrically insulative material may include electrical routing features disposed therein. In addition, a plurality of die interconnect structures (e.g., die interconnect structure  1116 ) may be disposed in the one or more layers of the electrically insulative material. In embodiments, the electrical routing features may be configured to electrically couple the die interconnect structures with the plurality of active components. In some embodiments, IC die  1100  may have a metal-insulator-metal (MIM) capacitor  1128  formed thereon. MIM capacitor  1128  may be formed as discussed above in reference to  FIGS. 2-4 . The MIM capacitor  1128  may have an electrical connection formed at  1122  on a terminal of a second metal layer with an interconnect structure disposed in one or more backside redistribution layers (RDLs)  1130 . The MIM capacitor  1128  may also have an electrical connection formed at  1120  on a terminal of a first metal layer with TSV  1109   b  to electrically couple MIM capacitor  1128  with the active side of semiconductor substrate  1108 . Electrical connections may be configured to route electrical signals between a second die  1126  and MIM capacitor  1128  by way of die interconnect structures  1124   b . In addition, in the embodiment depicted, electrical signals may be routed between second die  1126  and the active side of semiconductor substrate  1108  through TSV  1109 , by way of die interconnect structure  1124   a.    
     IC die  1102  depicts a similar configuration to that of IC die  1100 ; however, MIM capacitor  1128  has been replaced with trench capacitor  1132 . Such a trench capacitor may be formed as described above in reference to  FIGS. 5-7 . IC die  1104 , again, depicts a similar configuration to that of IC die  1100 ; however, MIM capacitor  1128  has been replaced with thin film resistor  1134 . Such a thin film resistor may be formed as described above in reference to  FIGS. 8 and 9 . 
     Embodiments of the present disclosure may be implemented into a system using any suitable hardware and/or software to configure as desired.  FIG. 12  schematically illustrates a computing device that includes an IC die as described herein, such as that depicted by  FIGS. 1-11 . The computing device  1200  may house a board such as motherboard  1202 . The motherboard  1202  may include a number of components, including but not limited to a processor  1204  and at least one communication chip  1206 . The processor  1204  may be physically and electrically coupled to the motherboard  1202 . In some implementations, the at least one communication chip  1206  may also be physically and electrically coupled to the motherboard  1202 . In further implementations, the communication chip  1206  may be part of the processor  1204 . 
     Depending on its applications, computing device  1200  may include other components that may or may not be physically and electrically coupled to the motherboard  1202 . These other components may include, but are not limited to, volatile memory (e.g., dynamic random access memory (DRAM)), non-volatile memory (e.g., read-only memory (ROM)), flash memory, a graphics processor, a digital signal processor, a crypto processor, a chipset, an antenna, a display, a touchscreen display, a touchscreen controller, a battery, an audio codec, a video codec, a power amplifier, a global positioning system (GPS) device, a compass, a Geiger counter, an accelerometer, a gyroscope, a speaker, a camera, and a mass storage device (such as hard disk drive, compact disk (CD), digital versatile disk (DVD), and so forth). 
     The communication chip  1206  may enable wireless communications for the transfer of data to and from the computing device  1200 . The term “wireless” and its derivatives may be used to describe circuits, devices, systems, methods, techniques, communications channels, etc., that may communicate data through the use of modulated electromagnetic radiation through a non-solid medium. The term does not imply that the associated devices do not contain any wires, although in some embodiments they might not. The communication chip  1206  may implement any of a number of wireless standards or protocols, including but not limited to Institute for Electrical and Electronic Engineers (IEEE) standards including Wi-Fi (IEEE 802.11 family), IEEE 802.16 standards (e.g., IEEE 802.16-2005 Amendment), Long-Term Evolution (LTE) project along with any amendments, updates, and/or revisions (e.g., advanced LTE project, ultra mobile broadband (UMB) project (also referred to as “3GPP2”), etc.). IEEE 802.16 compatible broadband wireless access (BWA) networks are generally referred to as WiMAX networks, an acronym that stands for Worldwide Interoperability for Microwave Access, which is a certification mark for products that pass conformity and interoperability tests for the IEEE 802.16 standards. The communication chip  1206  may operate in accordance with a Global System for Mobile Communication (GSM), General Packet Radio Service (GPRS), Universal Mobile Telecommunications System (UMTS), High Speed Packet Access (HSPA), Evolved HSPA (E-HSPA), or LTE network. The communication chip  1206  may operate in accordance with Enhanced Data for GSM Evolution (EDGE), GSM EDGE Radio Access Network (GERAN), Universal Terrestrial Radio Access Network (UTRAN), or Evolved UTRAN (E-UTRAN). The communication chip  1206  may operate in accordance with Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Digital Enhanced Cordless Telecommunications (DECT), Evolution-Data Optimized (EV-DO), derivatives thereof, as well as any other wireless protocols that are designated as 3G, 4G, 5G, and beyond. The communication chip  1206  may operate in accordance with other wireless protocols in other embodiments. 
     The computing device  1200  may include a plurality of communication chips  1206 . For instance, a first communication chip  1206  may be dedicated to shorter range wireless communications such as Wi-Fi and Bluetooth and a second communication chip  1206  may be dedicated to longer range wireless communications such as GPS, EDGE, GPRS, CDMA, WiMAX, LTE, Ev-DO, and others. 
     The processor  1204  of the computing device  1200  may be an IC die (e.g., IC die  106  of  FIG. 1 ) incorporated into an IC assembly that may include a package substrate (e.g., package substrate  116  of  FIG. 1 ). For example, the circuit board  124  of  FIG. 1  may be a motherboard  1202  and the processor  1204  may be IC die  106 . The processor  1204  and the motherboard  1202  may be coupled together using package-level interconnects as described herein. The term “processor” may refer to any device or portion of a device that processes electronic data from registers and/or memory to transform that electronic data into other electronic data that may be stored in registers and/or memory. 
     The communication chip  1206  may be an IC die (e.g., IC die  106 ) incorporated into an IC assembly that may include a package substrate (e.g., package substrate  116  of  FIG. 1 ). In further implementations, another component (e.g., memory device or other integrated circuit device) housed within the computing device  1200  may be an IC die (e.g., IC die  106 ) incorporated into an IC assembly. 
     In various implementations, the computing device  1200  may be a laptop, a netbook, a notebook, an ultrabook, a smartphone, a tablet, a personal digital assistant (PDA), an ultra mobile PC, a mobile phone, a desktop computer, a server, a printer, a scanner, a monitor, a set-top box, an entertainment control unit, a digital camera, a portable music player, or a digital video recorder. In further implementations, the computing device  1200  may be any other electronic device that processes data. 
     EXAMPLES 
     According to various embodiments, the present disclosure describes a number of examples. Example 1 may include an integrated circuit (IC) die comprising: a semiconductor substrate; a plurality of active components disposed on a first side of the semiconductor substrate; a plurality of passive components disposed on a second side of the semiconductor substrate, wherein the second side is disposed opposite the first side, and wherein the plurality of passive components are selected from the group consisting of: capacitors or resistors. 
     Example 2 may include the subject matter of Example 1, further comprising a plurality of through-substrate vias (TSVs) disposed in the semiconductor substrate and configured to route electrical signals between one or more of the plurality of passive components and the first side of the semiconductor substrate. 
     Example 3 may include the subject matter of Example 1, further comprising: one or more layers of electrically insulative material disposed on the first side of the semiconductor substrate, wherein the one or more layers of electrically insulative material encapsulate the plurality of active components; a plurality of die-level interconnects disposed in the one or more layers of the electrically insulative material; and electrical routing features disposed in the one or more layers of electrically insulative material, wherein the electrical routing features are configured to electrically couple the die-level interconnects with the plurality of active components. 
     Example 4 may include the subject matter of Example 3, wherein the one or more layers of electrically insulative material are one or more first layers of electrically insulative material, the electrical routing features are first electrical routing features, the IC die further comprising: one or more redistribution layers (RDLs) disposed on the second side of the semiconductor substrate, wherein the one or more redistribution layers include: one or more second layers of electrically insulative material disposed on the second side of the semiconductor substrate, wherein the one or more second layers of electrically insulative material encapsulate the plurality of passive components; a plurality of input/output (I/O) interconnect structures disposed in the one or more second layers of the electrically insulative material; and second electrical routing features disposed in the one or more second layers of electrically insulative material, wherein the second electrical routing features are configured to electrically couple the plurality of I/O interconnect structures with the plurality of passive components. 
     Example 5 may include the subject matter of Example 1, wherein the plurality of passive components comprise a plurality of metal-insulator-metal (MIM) capacitors, wherein each of the plurality of MIM capacitors include a first metal layer, a capacitor dielectric layer disposed on the first metal layer, and a second metal layer disposed on the capacitor dielectric layer. 
     Example 6 may include the subject matter of Example 1, wherein the plurality of passive components comprise a plurality of trench capacitors, wherein each of the plurality of trench capacitors include a first metal layer disposed on one or more trenches formed in the semiconductor substrate, a capacitor dielectric layer disposed on the first metal layer, and a second metal layer disposed on the capacitor dielectric layer. 
     Example 7 may include the subject matter of either of Examples 5 or 6, wherein the first and second metal layers are respectively electrically coupled with first and second interconnect structures disposed in one or more redistribution layers (RDLs) that are disposed on the second side of the semiconductor substrate. 
     Example 8 may include the subject matter of either of Examples 5 or 6, wherein the first metal layer is electrically coupled with a TSV disposed in the semiconductor substrate, wherein the TSV electrically couples the first side of the semiconductor substrate with the second side of the semiconductor substrate. 
     Example 9 may include the subject matter of Example 8, wherein the second metal layer is electrically coupled with an electrical routing structure of the IC die, wherein the electrical routing structure is selected from the group consisting of: an additional TSV disposed in the semiconductor substrate, wherein the additional TSV electrically couples the first side of the substrate with the second side of the semiconductor substrate; or an interconnect structure disposed in one or more redistribution layers (RDLs) that are disposed on the second side of the semiconductor substrate. 
     Example 10 may include the subject matter of Example 1, wherein the plurality of passive components comprise a plurality of thin film resistors wherein each thin film resistor includes a first terminal and a second terminal. 
     Example 11 may include the subject matter of Example 10, wherein the first and second terminal are respectively electrically coupled with first and second interconnect structures disposed in one or more redistribution layers (RDLs) that are disposed on the second side of the semiconductor substrate. 
     Example 12 may include the subject matter of Example 10, wherein the first terminal is electrically coupled with a TSV disposed in the semiconductor substrate, wherein the TSV electrically couples the first side of the semiconductor substrate with the second side of the semiconductor substrate. 
     Example 13 may include the subject matter of Example 12, wherein the second terminal is electrically coupled with an electrical routing structure of the IC die, wherein the electrical routing structure is selected from the group consisting of: an additional TSV disposed in the semiconductor substrate, wherein the additional TSV electrically couples the first side of the substrate with the second side of the semiconductor substrate; or an interconnect structure disposed in one or more redistribution layers (RDLs) that are disposed on the second side of the semiconductor substrate. 
     Example 14 may include the subject matter of Example 1, wherein the plurality of active components comprise transistors. 
     Example 15 may include the subject matter of Example 1, wherein the semiconductor substrate comprises a silicon wafer. 
     Example 16 may include a method of forming an integrated circuit (IC) die assembly comprising: providing a semiconductor substrate; forming a plurality of active components on a first side of the semiconductor substrate; forming a plurality of passive components on a second side of the semiconductor substrate, wherein the second side of the semiconductor substrate is disposed opposite the first side of the semiconductor substrate. 
     Example 17 may include the subject matter of Example 16, wherein the plurality of passive components are selected from the group consisting of: metal-insulator-metal (MIM) capacitors, and wherein forming the plurality of passive components includes: depositing a first metal layer on the second side of the semiconductor substrate; depositing a capacitor dielectric layer on the first metal layer; and depositing a second metal layer on the capacitor dielectric layer; and trench capacitors, wherein forming the plurality of passive components includes: forming one or more trenches in a surface of the second side of the semiconductor substrate; depositing a first metal layer on the one or more trenches; depositing a capacitor dielectric layer on the first metal layer; and depositing a second metal layer on the capacitor dielectric layer. 
     Example 18 may include the subject matter of Example 17, further comprising: forming one or more redistribution layers (RDLs) on the passive components, wherein the one or more RDLs include a plurality of interconnect structures, and wherein the one or more RDLs are formed to electrically couple a first and second interconnect structure of the plurality of interconnect structures with the first and second metal layers, respectively. 
     Example 19 may include the subject matter of Example 17, wherein the semiconductor substrate includes a TSV disposed therein that electrically couples the first side of the semiconductor substrate and the second side of the semiconductor substrate, and wherein the first metal layer is formed to electrically couple with the TSV. 
     Example 20 may include the subject matter of Example 17, wherein the second metal layer is formed to electrically couple with an electrical routing structure of the IC die, wherein the electrical routing structure is selected from the group consisting of: an additional TSV formed in the semiconductor substrate, wherein the additional TSV electrically couples the first side of the semiconductor substrate with the second side of the semiconductor substrate; or one or more redistribution layers (RDLs) formed on the second side of the semiconductor substrate having interconnect structures formed therein. 
     Example 21 may include the subject matter of Example 16, further comprising: depositing one or more layers of an electrically insulative material on the plurality of active components; forming electrical routing features in the one or more layers of electrically insulative material; and forming a plurality of die-level interconnect structures in a surface of the one or more layers of the electrically insulative material, wherein the plurality of die-level interconnect structures are electrically coupled with the plurality of active components via the electrical routing features. 
     Example 22 may include the subject matter of Example 21, wherein the electrically insulative material is first electrically insulative material, the electrical routing features are first electrical routing features, and further comprising: depositing one or more layers of second electrically insulative material on the plurality of passive components; forming electrical routing features in the one or more layers of second electrically insulative material; and forming a plurality of input/output (I/O) interconnect structures in the one or more layers of the second electrically insulative material, wherein the plurality of I/O interconnect structures are electrically coupled with one or more of the plurality of passive components via the electrical routing features. 
     Example 23 may include an integrated circuit (IC) package assembly comprising: an integrated circuit (IC) die having: a plurality of active components disposed on a first side of a semiconductor substrate; a plurality of passive components disposed on a second side of the semiconductor substrate, wherein the second side of the semiconductor substrate is disposed opposite the first side of the semiconductor substrate; a first plurality of input/output (I/O) interconnect structures electrically coupled with the plurality of active components; and a second plurality of I/O interconnect structures electrically coupled with the plurality of passive components; and a package substrate electrically coupled with the IC die, wherein the package substrate is configured to route electrical signals of the IC die. 
     Example 24 may include the subject matter of Example 23, wherein the IC die is a first IC die and further comprising a second IC die disposed on the second side of the semiconductor substrate, wherein the second IC die includes a third plurality of I/O interconnect structures coupled with the second plurality of I/O interconnect structures to route electrical signals between the first IC die and the second IC die. 
     Example 25 may include the subject matter of Example 23, wherein the passive components are selected from a group consisting of: metal-insulator-metal (MIM) capacitors; trench capacitors; and thin film resistors. 
     Various embodiments may include any suitable combination of the above-described embodiments including alternative (or) embodiments of embodiments that are described in conjunctive form (and) above (e.g., the “and” may be “and/or”). Furthermore, some embodiments may include one or more articles of manufacture (e.g., non-transitory computer-readable media) having instructions, stored thereon, that when executed result in actions of any of the above-described embodiments. Moreover, some embodiments may include apparatuses or systems having any suitable means for carrying out the various operations of the above-described embodiments. 
     The above description of illustrated implementations, including what is described in the Abstract, is not intended to be exhaustive or to limit the embodiments of the present disclosure to the precise forms disclosed. While specific implementations and examples are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the present disclosure, as those skilled in the relevant art will recognize. 
     These modifications may be made to embodiments of the present disclosure in light of the above detailed description. The terms used in the following claims should not be construed to limit various embodiments of the present disclosure to the specific implementations disclosed in the specification and the claims. Rather, the scope is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.