Patent Publication Number: US-2022238636-A1

Title: High capacitance mim device with self aligned spacer

Description:
REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 63/142,026, filed on Jan. 27, 2021, the contents of which are hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND 
     Integrated chips are formed on semiconductor die comprising millions or billions of transistor devices. The transistor devices are configured to act as switches and/or to produce power gains so as to enable logical functionality for an integrated chip (e.g., form a processor configured to perform logic functions). Integrated chips also comprise passive devices, such as capacitors, resistors, inductors, varactors, etc. Passive devices are widely used to control integrated chip characteristics, such as gains, time constants, etc. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. 
         FIG. 1  illustrates a cross-sectional view of some embodiments of an integrated chip having a high density MIM (metal-insulator-metal) capacitor structure. 
         FIG. 2  illustrates a cross-sectional view of some additional embodiments of an integrated chip having a high density MIM capacitor structure. 
         FIGS. 3A-3D  illustrate some additional embodiments of an integrated chip having a high density MIM capacitor structure. 
         FIG. 4  illustrates a cross-sectional view of some additional embodiments of an integrated chip having a high density MIM capacitor structure. 
         FIGS. 5A-5C  illustrate cross-sectional views of some additional embodiments of integrated chips having a high density MIM capacitor structure. 
         FIG. 6  illustrates a cross-sectional view of some additional embodiments of an integrated chip having a high density MIM capacitor structure. 
         FIGS. 7-17  illustrate cross-sectional views of some embodiments of a method of forming an integrated chip having a high density MIM capacitor structure. 
         FIG. 18  illustrates a flow diagram of some embodiments of a method of forming an integrated chip having a high density MIM capacitor structure. 
         FIGS. 19-29  illustrate cross-sectional views of some alternative embodiments of a method of forming an integrated chip having a high density MIM capacitor structure. 
         FIG. 30  illustrates a flow diagram of some alternative embodiments of a method of forming an integrated chip having a high density MIM capacitor structure. 
     
    
    
     DETAILED DESCRIPTION 
     The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. 
     Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly. 
     A MIM (metal-insulator-metal) capacitor is a passive device that is typically arranged within a back-end-of-the line (BEOL) stack of an integrated chip. A MIM capacitor may be formed by depositing a capacitor dielectric layer over a lower electrode layer and subsequently depositing an upper electrode layer over the capacitor dielectric layer. One or more patterning processes are performed to remove parts of the upper electrode layer, the capacitor dielectric layer, and the lower electrode layer and to define a MIM capacitor having a capacitor dielectric disposed between an upper electrode and a lower electrode. 
     It has been appreciated that using a single patterning process to remove parts of the upper and lower electrode layers may cause metal from the upper and/or lower electrode layers to re-deposit and/or accumulate along sides of the upper electrode, the lower electrode, and the capacitor dielectric during fabrication, thereby electrically shorting the upper and lower electrodes. To prevent re-deposited metal from shorting the upper and lower electrodes, separate patterning processes may be used to etch the upper and lower electrode layers. For example, the upper electrode layer may be patterned according to a first patterning process that uses a first photomask, while the capacitor dielectric layer and the lower electrode layer may be subsequently patterned according to a second patterning process that uses a second photomask. 
     However, alignment tolerances between the different photomasks used to form a MIM capacitor cause a lower electrode of a capacitor to have a significantly larger footprint than an upper electrode of the capacitor. For example, an upper electrode may have a footprint that is between 50% and 70% of the lower electrode. Because a capacitance of a MIM capacitor is directly proportional to an area of both the upper and the lower conductive electrodes, such alignment tolerances can cause MIM capacitors to consume a relatively large footprint (e.g., surface area) of an integrated chip to achieve a capacitances used in integrated chip applications. For example, a MIM capacitor may have a footprint that is on the order of approximately 10 microns 2 . Furthermore, while the minimum feature sizes of integrated chips (e.g., gate sizes, metal interconnect sizes, etc.) continue to decrease, a MIM capacitor is unable to similarly scale its size without decreasing its capacitance. Therefore, as the minimum features sizes of integrated chips decrease MIM capacitors are consuming proportionally larger areas of a substrate to achieve a same capacitance, and thus are becoming increasingly expensive. 
     The present disclosure relates to a method of forming a MIM device comprising upper and lower electrodes with footprints having similar sizes (e.g., having footprints with sizes that are within approximately 10% of one another). In some embodiments, the method may be performed by forming a capacitor dielectric layer over the lower electrode layer, and forming an upper electrode layer over the capacitor dielectric layer. A first etching process is performed to pattern the upper electrode layer and define an upper electrode. A spacer layer is subsequently formed over horizontally extending surfaces of the upper electrode and the capacitor dielectric layer and also along sidewalls of the upper electrode. The spacer layer is etched using a second etching process that removes the spacer layer from over the horizontally extending surfaces of the upper electrode and the capacitor dielectric layer, and that defines a self-aligned spacer along the sidewalls of the upper electrode. A third etching process is subsequently performed to pattern the capacitor dielectric layer and the lower electrode layer according to the self-aligned spacer. Using the self-aligned spacer to pattern the lower electrode layer allows for the upper and lower electrodes to be formed to have footprints with similar sizes. By forming upper and lower electrodes with footprints that have similar sizes, a capacitance of a resulting MIM device can be improved without increasing an overall footprint of the MIM device. 
       FIG. 1  illustrates a cross-sectional view of some embodiments of an integrated chip  100  having a high density MIM (metal-insulator-metal) capacitor structure. 
     The integrated chip  100  comprises one or more lower interconnects  104  disposed within a lower dielectric structure  106  over a substrate  102 . A first etch stop layer  108  is disposed over the lower dielectric structure  106  and a first dielectric layer  110  is disposed over the first etch stop layer  108 . The first dielectric layer  110  comprises one or more sidewalls  110   s  that define an opening extending through the first dielectric layer  110 . 
     A MIM capacitor structure  111  is arranged over the one or more lower interconnects  104 . The MIM capacitor structure  111  comprises a capacitor dielectric  114  disposed vertically between a lower electrode  112  and an upper electrode  116 . In some embodiments, the MIM capacitor structure  111  extends through the opening in the first dielectric layer  110  to electrically contact the one or more lower interconnects  104 . In some such embodiments, the capacitor dielectric  114  may be disposed both vertically and laterally between the lower electrode  112  and the upper electrode  116 . In such embodiments, the lower electrode  112  is arranged along an upper surface and the one or more sidewalls  110   s  of the first dielectric layer  110 , the capacitor dielectric  114  is arranged along an upper surface and one or more sidewalls of the lower electrode  112 , and the upper electrode  116  is arranged along an upper surface and one or more sidewalls of the capacitor dielectric  114 . In some embodiments, a capping structure  118  is arranged over the upper electrode  116 . In some such embodiments, an upper interconnect structure  122  (e.g., an interconnect via) extends through the capping structure  118  to contact the upper electrode  116 . 
     A spacer  120  (e.g., a self-aligned spacer) is arranged along opposing outermost sidewalls of the upper electrode  116  and the capping structure  118 . The spacer  120  has a lowermost surface  120 L that is disposed on an upper surface of the capacitor dielectric  114 . In some embodiments, the lowermost surface  120 L of the spacer  120  directly contacts the upper surface of the capacitor dielectric  114 . In some additional embodiments, an entirety of the spacer  120  is completely confined over the upper surface of the capacitor dielectric  114 . The spacer  120  has an outermost surface  120   s  that continuously extends between an uppermost surface of the spacer  120  and the lowermost surface  120 L of the spacer  120 . The outermost surface  120   s  of the spacer  120  is substantially aligned with outermost sidewalls of the capacitor dielectric  114  and the lower electrode  112 . In some embodiments, the outermost surface  120   s  of the spacer  120  and the outermost sidewalls of the capacitor dielectric  114  and the lower electrode  112  form a substantially smooth surface. 
     The spacer  120  has a width  124  that is relatively small. For example, the spacer  120  may have a width  124  that is in a range of between approximately 50 Angstroms (Å) and approximately 1,000 Å, between approximately 250 Å and approximately 750 Å, between approximately 400 Å and approximately 600 Å, approximately 500 Å, or other similar values. During fabrication, the spacer  120  is used as a mask in an etching process that defines the capacitor dielectric  114  and the lower electrode  112 . Because of the relatively small width  124  of the spacer  120 , the lower electrode  112  can be formed to have a footprint that is similar to that of the upper electrode  116 . For example, in some embodiments, the upper electrode  116  may have a first footprint  126  that covers between approximately 90% and approximately 95% of a second footprint  128  of the lower electrode  112 . In other embodiments, the first footprint  126  of the upper electrode  116  may cover between approximately 85% and approximately 99% of the second footprint  128 . By having the first footprint  126  of the upper electrode  116  with a similar size to the second footprint  128  of the lower electrode  112 , a capacitance of the MIM capacitor structure  111  can be improved without increasing an overall footprint of the MIM capacitor structure  111 . For example, a MIM capacitor structure formed using separate photomasks to define the upper and lower electrodes may have a capacitance that is between 50% and 75% of a capacitance of a disclosed MIM capacitor structure that has a same footprint and that uses a self-aligned spacer to define the lower electrode (e.g., a capacitor formed using separate patterning processes may have a capacitance of approximately 175 femto-Farads (fF) to approximately 225 fF, while a disclosed MIM capacitor structure with a same footprint may have a capacitance of approximately 345 fF to approximately 400 fF) 
       FIG. 2  illustrates a cross-sectional view of some additional embodiments of an integrated chip  200  having a high density MIM capacitor structure. 
     The integrated chip  200  comprises one or more lower interconnects  104  disposed within a lower dielectric structure  106  over a substrate  102 . In some embodiments, the one or more lower interconnects  104  may be coupled to a transistor device  202  disposed within the substrate  102 . The lower dielectric structure  106  may comprise a plurality of stacked inter-level dielectric (ILD) layers  106   a - 106   b  disposed over the substrate  102 . In some embodiments, the plurality of stacked ILD layers  106   a - 106   b  may comprise one or more of silicon dioxide, silicon nitride, carbon doped silicon dioxide, silicon oxynitride, borosilicate glass (BSG), phosphorus silicate glass (PSG), borophosphosilicate glass (BPSG), fluorosilicate glass (FSG), undoped silicate glass (USG), a porous dielectric material, or the like. In some embodiments, the one or more lower interconnects  104  may comprise one or more of a middle-of-line (MOL) interconnect, a conductive contact, an interconnect wire, an interconnect via, or the like. In some embodiments, the one or more lower interconnects  104  may comprise one or more of copper, tungsten, ruthenium, aluminum, and/or the like. 
     A first etch stop layer  108  is disposed over the lower dielectric structure  106  and a first dielectric layer  110  is disposed over the first etch stop layer  108 . A MIM capacitor structure  111  is arranged over the first dielectric layer  110 . The MIM capacitor structure  111  extends through the first dielectric layer  110  and the first etch stop layer  108  to electrically contact the one or more lower interconnects  104 . In some embodiments, the MIM capacitor structure  111  comprises a lower electrode  112  arranged along an upper surface and one or more sidewalls of the first dielectric layer  110 , a capacitor dielectric  114  arranged along an upper surface and one or more sidewalls of the lower electrode  112 , and an upper electrode arranged an upper surface and one or more sidewalls of the capacitor dielectric  114 . 
     In some embodiments, the lower electrode  112  and the upper electrode  116  may respectively comprise a metal such as aluminum, copper, tantalum, titanium, tantalum nitride, titanium nitride, tungsten, and/or the like. In some embodiments, the lower electrode  112  comprises a same metal as the upper electrode  116 , while in other embodiments the lower electrode  112  and the upper electrode  116  may comprise different metals. The lower electrode  112  and the upper electrode  116  respectively have a thickness that is in a range of between approximately 10 Angstroms (Å) and approximately 200 Å, between approximately 50 Å and approximately 100 Å, or other similar values. In some embodiments, the capacitor dielectric  114  may comprise a high-k dielectric material. In some embodiments, the capacitor dielectric  114  may comprise one or more of aluminum oxide (Al 2 O 3 ), hafnium oxide (HfO 2 ), silicon dioxide (SiO 2 ), silicon carbide (SiC), silicon mononitride (SiN), silicon nitride (Si 3 N 4 ), tantalum nitride (Ta 2 O 5 ), tantalum oxynitride (TaON), titanium oxide (TiO 2 ), zirconium oxide (ZrO 2 ), or the like. 
     In some embodiments a dielectric  204  covers an upper surface of the upper electrode  116  and extends between interior sidewalls of the upper electrode  116 . In some embodiments, the dielectric  204  continuously extends from over the upper electrode  116  to directly between the interior sidewalls of the upper electrode  116 . In some embodiments, the dielectric  204  may comprise an oxide (e.g., silicon oxide, silicon dioxide), a nitride (e.g., silicon nitride), or the like. 
     A capping structure  118  is arranged over the upper electrode  116 . In some embodiments, the capping structure  118  is vertically separated from the upper electrode  116  by way of the dielectric  204 . In some embodiments, the capping structure  118  is configured to prevent interaction between adjacent layers (e.g., to prevent diffusion from the capacitor metal layers to an adjacent dielectric material) and/or to protect underlying layers during manufacturing. In some embodiments, a capping structure  118  may comprise a dielectric material such as silicon oxynitride, silicon oxycarbide, or the like. The capping structure  118  and the masking layer  206  have substantially equal widths. In some embodiments, a masking layer  206  is arranged over the capping structure  118 . In some embodiments, the masking layer may comprise an anti-reflective layer. In various embodiments, the masking layer  206  may comprise a dielectric such as silicon nitride, silicon carbide, or the like. 
     A spacer  120  is arranged along opposing sides of the upper electrode  116 , the capping structure, and/or the masking layer  206 . The spacer  120  has an outermost surface that faces away from the upper electrode  116  and that continuously extends between a lowermost surface of the spacer  120  and a top and/or a topmost surface of the spacer  120 . In some embodiments, the outermost surface of the spacer  120  may comprise a curved surface. For example, the outermost surface of the spacer  120  may comprise a vertically extending segment and a curved segment over the vertically extending segment. In some such embodiments, the vertically extending segment is substantially aligned with outermost sidewalls of the capacitor dielectric  114  and the lower electrode  112 . In some embodiments, the first dielectric layer  110  may comprise a sidewall  110   s  that is also substantially aligned with the vertically extending segment of the spacer  120 . In some embodiments, the spacer  120  comprises outermost sidewalls that are completely confined between an outermost sidewall of the upper electrode  116  facing a first direction and an outermost sidewall of the lower electrode  112  facing the same first direction. 
     In some embodiments, the spacer  120  comprises a first dielectric  208  and a second dielectric  210  over the first dielectric  208 . The first dielectric  208  extends along a lower surface and a sidewall of the second dielectric  210 . The first dielectric  208  comprises a horizontally extending segment separating the second dielectric  210  from the capacitor dielectric  114  and a vertically extending segment separating the second dielectric  210  from the upper electrode  116  and the capping structure  118 . In some embodiments, the first dielectric  208  may comprise a first dielectric material and the second dielectric  210  may comprise a second dielectric material that is different than the first dielectric material. In some embodiments, the first dielectric  208  may comprise an oxide (e.g., silicon dioxide, silicon rich oxide, or the like), while the second dielectric  210  may comprise a nitride (e.g., silicon nitride), a carbide (e.g., silicon carbide), or the like. 
     A second dielectric layer  212  is arranged over the MIM capacitor structure  111  and the first dielectric layer  110 . In some embodiments, the second dielectric layer  212  is arranged along an upper surface and the sidewall  110   s  of the first dielectric layer  110 . In some embodiments, the second dielectric layer  212  may have a single sidewall that extends along the outer surface of the spacer  120 , the outermost sidewalls of the capacitor dielectric  114  and the lower electrode  112 , and along the sidewall  110   s  of the first dielectric layer  110 . In some embodiments, the second dielectric layer  212  may comprise one or more of silicon dioxide, silicon nitride, carbon doped silicon dioxide, silicon oxynitride, BSG, PSG, BPSG, FSG, USG, a porous dielectric material, or the like. In some embodiments, an upper interconnect structure  122  (e.g., an interconnect via) extends through the second dielectric layer  212 , the masking layer  206 , the capping structure  118 , and the dielectric  204  to contact the upper electrode  116 . 
       FIG. 3A  illustrates a cross-sectional view of some additional embodiments of an integrated chip  300  having a high density MIM capacitor structure comprising a plurality of protrusions extending outward from a lower surface of the MIM capacitor structure. 
     The integrated chip  300  comprises a first dielectric layer  110  disposed over a substrate  102 . The first dielectric layer  110  comprises sidewalls defining a plurality of openings extending through the first dielectric layer  110 . A MIM capacitor structure  111  is arranged over the first dielectric layer  110  and comprises a plurality of protrusions  302   a - 302   c  that extend outward from a lower surface of the MIM capacitor structure  111  to within the plurality of openings. The plurality of protrusions  302   a - 302   c  respectively comprise a lower electrode  112 , a capacitor dielectric  114 , and an upper electrode  116 . In some embodiments, the plurality of protrusions  302   a - 302   c  further comprise a dielectric  204 . One or more of the plurality of protrusions  302   a - 302   c  contact one or more lower interconnects  104  within a lower dielectric structure  106  between the first dielectric layer  110  and the substrate  102 . 
     By having a plurality of protrusions  302   a - 302   c  extending outward from the lower surface of the MIM capacitor structure  111 , a capacitance of the MIM capacitor structure  111  can be further increased since the protrusions increase a surface area of the upper electrode  116  and the lower electrode  112 . For example, a MIM capacitor structure  111  with three protrusions may have a capacitance that is between approximately 50% and approximately 70% greater than a MIM capacitor structure with 2 protrusions. In some embodiments, the plurality of protrusions  302   a - 302   c  may comprise three protrusions. In other embodiments (not shown), the plurality of protrusions  302   a - 302   c  may comprise more than three protrusions (e.g., 4 protrusions, 5 protrusions, etc.). 
       FIG. 3B  illustrates a top-view  304  of the integrated chip of  FIG. 3A . The cross-sectional view of  FIG. 3A  is taken along cross-sectional line A-A′ of top-view  304 . 
     As shown in top-view  304 , the plurality of protrusions  302   a - 302   c  of the MIM capacitor structure  111  respectively have a substantially rectangular shape that extends a first distance along a first direction  306  and that extends a second distance along a second direction  308 , which is perpendicular to the first direction  306 . The second distance is greater than the first distance. 
     Within each of the plurality of protrusions  302   a - 302   c , the lower electrode  112  completely surrounds the dielectric  204 , the capacitor dielectric  114  completely surrounds the lower electrode  112 , and the upper electrode  116  completely surrounds the capacitor dielectric  114 . The upper electrode  116  continuously extends past the plurality of protrusions  302   a - 302   c  along a first direction  306  and along a second direction  308  that is perpendicular to the first direction  306 . The spacer  120  extends around a perimeter of the upper electrode  116  in a closed path. The lower electrode  112  and the capacitor dielectric  114  have outermost perimeters that are substantially the same as an outermost perimeter of the spacer  120 . In such embodiments, a collective footprint of both the upper electrode  116  and/or the spacer  120  is substantially equal to a footprint of the lower electrode  112 . 
     It will be appreciated that in various embodiments, a disclosed MIM capacitor structure may have a plurality of protrusions (e.g.,  302   a - 302   c  of  FIG. 3A ) defined by different shapes. For example,  FIGS. 3C-3D  illustrate some embodiments of alternative shapes of the plurality of protrusions within a disclosed MIM capacitor structure. The different shapes of the plurality of protrusions may affect electric field characteristics within the disclosed MIM capacitor structure, thereby affecting performance of the MIM capacitor structure. The shapes of the plurality of protrusions shown in  FIGS. 3C-3D  are not limiting examples of possible protrusion shapes, and protrusions having other shapes are also believed to fall within the scope of this disclosure. 
       FIG. 3C  illustrates a top-view  310  of some alternative embodiments of an integrated chip having a high density MIM capacitor structure comprising a plurality of protrusions. 
     As shown in top-view  310 , the MIM capacitor structure  111  comprises a plurality of protrusions  312 . The plurality of protrusions  312  have a substantially circular shape. In some embodiments, the plurality of protrusions  312  may be arranged in an array. In some such embodiments, a plurality of protrusions  312  may be aligned in rows (extending in the first direction  306 ) and columns (extending in the second direction  308 ). 
       FIG. 3D  illustrates a top-view  314  of some alternative embodiments of an integrated chip having a high density MIM capacitor structure comprising a plurality of protrusions. 
     As shown in top-view  314 , the MIM capacitor structure  111  comprises a plurality of protrusions  316 . The plurality of protrusions  316  have a substantially square shape. In some embodiments, the plurality of protrusions  316  may be arranged in an array. In some such embodiments, a plurality of protrusions  316  may be aligned in rows (extending in the first direction  306 ) and columns (extending in the second direction  308 ). 
       FIG. 4  illustrates a cross-sectional view of some additional embodiments of an integrated chip  400  having a high density MIM capacitor structure. 
     The integrated chip  400  comprises one or more lower interconnects  104  disposed within a lower dielectric structure  106  over a substrate  102 . A first etch stop layer  108  is arranged over the lower dielectric structure  106  and a first dielectric layer  110  is arranged over the first etch stop layer  108 . A MIM capacitor structure, comprising a lower electrode  112 , a capacitor dielectric  114 , and an upper electrode  116 , is arranged over the first dielectric layer  110 . A spacer  120  is arranged along opposing sides of the upper electrode  116 . In some embodiments, the spacer  120  may have a curved upper surface. In some embodiments, a capping structure  118  is disposed over the upper electrode  116  and a masking layer  206  is over the capping structure  118 . A second dielectric layer  212  is disposed over the MIM capacitor structure. In some embodiments, the second dielectric layer  212  may extend over an upper surface of the spacer  120  and over a top surface of the masking layer  206 . 
     In some embodiments, the first dielectric layer  110  has sidewalls that are angled at a first angle θ 1 . The first angle θ 1  is an acute angle as measured through the first dielectric layer  110  and with respect to a lower surface of the first dielectric layer  110  facing the substrate  102 . The lower electrode  112  has a lower sidewall  112   L  extending through the first dielectric layer  110  and an upper sidewall  112   u  overlying the first dielectric layer  110 . The lower sidewall  112   L  is angled at a second angle θ 2 , while the upper sidewall  112   u  is angled at a third angle θ 3 . The second angle θ 2  is an obtuse angle as measured through the lower electrode  112  and with respect to a lower surface of the lower electrode  112  facing the substrate  102 . The third angle θ 3  is an acute angle as measured through the lower electrode  112  and with respect to a lower surface of the lower electrode  112  facing the substrate  102 . In some embodiments, the capacitor dielectric  114 , the upper electrode  116 , and the capping structure  118  may also have angled sidewalls as shown in  FIG. 4 . 
     In some embodiments, an upper dielectric structure  402  is disposed over the first dielectric layer  110  and the second dielectric layer  212 . In some embodiments, the upper dielectric structure  402  may comprise an upper etch stop layer  404  and an upper inter-level dielectric (ILD) layer  406 . In some embodiments, an upper interconnect structure  122  extends through the upper dielectric structure  402 , the masking layer  206 , the capping structure  118 , and the dielectric  204  to contact the upper electrode  116 . In some embodiments, the upper interconnect structure  122  may comprise an upper interconnect via  122   v  and an upper interconnect wire  122   w  over the upper interconnect via  122   v . In some embodiments, the upper interconnect structure  122  may extend to a non-zero distance  408  below a top surface of the upper electrode  116 . 
     In some embodiments, one or more conductive byproducts  410  (e.g., metal byproducts) may be arranged along sidewalls of the lower electrode  112 , the capacitor dielectric  114 , and/or the spacer  120 . The one or more conductive byproducts  410  result from a re-deposition of material etched away from a lower electrode layer during formation of the lower electrode  112 . Because the one or more conductive byproducts  410  are separated from the upper electrode  116  by the spacer  120 , the conductive byproducts are not able to form a conductive path between the lower electrode  112  and the upper electrode  116 , thereby preventing electrical shorting between the lower electrode  112  and the upper electrode  116 . In some additional embodiments (not shown), one or more additional conductive byproducts may be disposed along sidewalls of the upper electrode  116 . The one or more additional conductive byproducts may result from etching of an upper electrode layer to define the upper electrode  116  and may be covered by the spacer  120 , so that the one or more additional conductive byproducts are separated from the one or more conductive byproducts  410  by the spacer  120 . 
       FIG. 5A  illustrates a cross-sectional view of some additional embodiments of an integrated chip  500  having a high density MIM capacitor structure. 
     The integrated chip  500  comprises a MIM capacitor structure  111  arranged over one or more lower interconnects  104  disposed within a lower dielectric structure  106  over a substrate  102 . A capping structure  118  is arranged over the MIM capacitor structure  111 . The capping structure  118  may be separated from the upper electrode  116  by way of a dielectric  204 . A spacer  120  is arranged over the capping structure  118  and the capacitor dielectric  114 . In some embodiments, the spacer  120  may extend from directly over the upper electrode  116  and the capping structure  118  to laterally past opposing outermost sidewalls of the upper electrode  116  and the capping structure  118 . In some embodiments, the spacer  120  may extend a non-zero distance  506  past one or more of the opposing outermost sidewalls of the upper electrode  116  and the capping structure  118 . In some embodiments, the non-zero distance  506  may be in a range of between approximately 50 Å and approximately 750 Å. 
     In some embodiments, the spacer  120  extends from directly over the capping structure  118  to along a sidewall of the capping structure  118 . In such embodiments, the spacer  120  comprises a protrusion  120   p  that extends outward from a lower surface of the spacer  120  that directly overlies the capping structure  118 . In some embodiments, the spacer  120  may comprise an outermost surface  120   s  that is substantially aligned with outermost sidewalls of the capacitor dielectric  114  and the lower electrode  112 . In some embodiments, the outermost surface  120   s  may also be aligned with a sidewall of the first dielectric layer  110 . The outermost surface  120   s  continuously extends from a bottom of the spacer  120  to a top and/or a topmost surface of the spacer  120 . In some embodiments, the outermost surface  120   s  of the spacer  120  is substantially flat. 
     In some embodiments, the spacer  120  may comprise a first dielectric  502  and a second dielectric  504  that is a different dielectric material than the first dielectric  502 . In some embodiments, the first dielectric  502  lines sidewalls of the capping structure  118  and the upper electrode  116  and horizontally extending surfaces of the capping structure  118  and the capacitor dielectric  114 . In some embodiments, the second dielectric  504  lines sidewalls and horizontally extending surfaces of the first dielectric  502 . In some embodiments, the first dielectric  502  and the second dielectric  504  may completely cover uppermost surfaces of the capping structure  118  and the capacitor dielectric  114 . In some such embodiments, the second dielectric  504  may continuously extend from a first outermost sidewall that is aligned with a first outermost sidewall of the capacitor dielectric  114  to a second outermost sidewall that is aligned with an opposing second outermost sidewall of the capacitor dielectric  114 . 
       FIG. 5B  illustrates a cross-sectional view of some additional embodiments of an integrated chip  508  having a high density MIM capacitor structure. 
     The integrated chip  508  comprises a MIM capacitor structure  111  arranged over a substrate  102 . A capping structure  118  is arranged over the MIM capacitor structure  111 . A spacer  120  is arranged over the capping structure  118  and a capacitor dielectric  114  of the MIM capacitor structure  111 . In some embodiments, the spacer  120  may extend past outermost sidewalls of the upper electrode  116  and the capping structure  118 . 
     The spacer  120  comprises surfaces defining one or more cavities  510   a - 510   b  arranged along one or more outer sidewalls of the spacer  120 . The one or more cavities  510   a - 510   b  may vertically extend from a top of the spacer  120  to above a bottom of the capping structure  118 . In some embodiments, the one or more cavities  510   a - 510   b  may comprise a first cavity  510   a  and a second cavity  510   b  arranged along opposing sides of the spacer  120 . In some embodiments, the first cavity  510   a  may be laterally recessed a first distance  512  from a first outer sidewall of the spacer  120  and the second cavity  510   b  may be laterally recessed a second distance  514  from a second outer sidewall of the spacer  120 . In some embodiments, the first distance  512  may be approximately equal to the second distance  514 . In other embodiments, the first distance  512  may be less than to the second distance  514   
       FIG. 5C  illustrates a cross-sectional view of some additional embodiments of an integrated chip  516  having a high density MIM capacitor structure. 
     The integrated chip  516  comprises a spacer  120  having surfaces defining one or more cavities  510   a - 510   b  arranged along one or more outer sidewalls of the spacer  120 . In some embodiments, the one or more cavities  510   a - 510   b  may comprise a first cavity  510   a  and a second cavity  510   b  arranged along opposing sides of the spacer  120 . In some embodiments, the first cavity  510   a  may be vertically recessed a first distance  512  from a top of the spacer  120  and the second cavity may be vertically recessed a second distance from the top of the spacer  120 . In some embodiments, the first distance may be different than the second distance. In such embodiments, a first lower surface  518 L 1  defining the first cavity  510   a  is vertically offset from a second lower surface  518 L 2  defining the second cavity  510   b  by a non-zero distance  520 . 
       FIG. 6  illustrates a cross-sectional view of some additional embodiments of an integrated chip  600  having a high density MIM capacitor structure. 
     The integrated chip  600  comprises a first region  602  and a second region  604  that is laterally offset from the first region  602 . Within the first region  602 , one or more lower interconnects  104  are arranged within a lower dielectric structure  106  over a substrate  102 . A MIM capacitor structure  111  is arranged over both a first etch stop layer  108  and a first dielectric layer  110  that are over the lower dielectric structure  106 . The MIM capacitor structure  111  comprises one or more protrusions  302  that extend through the first dielectric layer  110  to contact the one or more lower interconnects  104 . 
     A second dielectric layer  212  is arranged along sidewalls of the first dielectric layer  110  and over upper surfaces of the first dielectric layer  110  and the first etch stop layer  108 . In some embodiments, the spacer  120  may have a flat upper surface that is substantially co-planar with an upper surface of the second dielectric layer  212  and/or a masking layer  206  (e.g., planar within a tolerance of a chemical mechanical planarization (CMP) process). An upper dielectric structure  402  is disposed over the first dielectric layer  110  and the second dielectric layer  212 . An upper interconnect structure  122  is arranged within the upper dielectric structure  402  and vertically extends through the masking layer  206  to electrically couple to the MIM capacitor structure  111 . 
     Within the second region  604 , one or more additional lower interconnects  612  are disposed within the lower dielectric structure  106 . The one or more additional lower interconnects  612  are coupled to an additional interconnect via  614  disposed within the second dielectric layer  212 . The additional interconnect via  614  is laterally separated from the MIM capacitor structure  111  by way of the first dielectric layer  110  and/or the second dielectric layer  212 . An additional upper interconnect structure  616  is disposed within the upper dielectric structure  402  and is coupled to the additional interconnect via  614 . 
     In some embodiments, the upper interconnect structure  122  and the additional upper interconnect structure  616  may be disposed within a topmost inter-level dielectric (ILD) layer and/or a topmost interconnect layer. In such embodiments, the upper interconnect structure  122  and/or the additional upper interconnect structure  616  are connected to a bond pad  606  disposed within a passivation layer  608 . In some embodiments, the bond pad  606  may be further coupled to an external bonding structure  610  (e.g., a solder bump, a micro-bump, or the like). Placement of the MIM capacitor structure  111  onto an interconnect layer immediately underlying the topmost ILD layer and/or the topmost interconnect layer provides the MIM capacitor structure  111  with a relatively large height (e.g., since a height of an ILD layer and/or interconnect layer generally increases as a distance from the substrate  102  increases). The relatively large height of the MIM capacitor structure  111  further increases a capacitance of the MIM capacitor structure  111  without increasing a footprint of the MIM capacitor structure  111 . 
       FIGS. 7-18  illustrate cross-sectional views of some embodiments of a method of forming an integrated chip having a high density MIM capacitor structure. Although  FIGS. 7-18  are described in relation to a method, it will be appreciated that the structures disclosed in FIGS.  7 - 18  are not limited to such a method, but instead may stand alone as structures independent of the method. 
     As shown in cross-sectional view  700  of  FIG. 7 , one or more lower interconnects  104  are formed within a lower dielectric structure  106  formed over a substrate  102 . In various embodiments, the substrate  102  may be any type of semiconductor body (e.g., silicon, SiGe, SOI, etc.), such as a semiconductor wafer and/or one or more die on a wafer, as well as any other type of semiconductor and/or epitaxial layers, associated therewith. In some embodiments, the one or more lower interconnects  104  may comprise one or more of a middle-of-line (MOL) interconnect, a conductive contact, an interconnect wire, and/or an interconnect via. 
     In some embodiments, the one or more lower interconnects  104  may be respectively formed using a damascene process (e.g., a single damascene process or a dual damascene process). In such embodiments, the one or more lower interconnects  104  may be respectively formed by forming an inter-level dielectric (ILD) layer over the substrate  102 , selectively etching the ILD layer to define a via hole and/or a trench within the ILD layer, forming a conductive material (e.g., copper, aluminum, etc.) within the via hole and/or the trench, and performing a planarization process (e.g., a chemical mechanical planarization (CMP) process) to remove excess of the conductive material from over the ILD layer. 
     As shown in cross-sectional view  800  of  FIG. 8 , a first etch stop layer  108  is formed over the lower dielectric structure  106  and a first dielectric layer  110  is formed over the first etch stop layer  108 . In some embodiments, the first etch stop layer  108  may comprise a nitride (e.g., silicon nitride), a carbide (e.g., silicon carbide), or the like. In some embodiments, the first dielectric layer  110  may comprise an oxide, a low-k dielectric material, or the like. In various embodiments, the first etch stop layer  108  and/or the first dielectric layer  110  may be formed by one or more deposition processes (e.g., a physical vapor deposition (PVD) process, a chemical vapor deposition (CVD) process, a plasma enhanced CVD (PE-CVD) process, an atomic layer deposition (ALD) process, or the like). 
     As shown in cross-sectional view  900  of  FIG. 9A  (taken along a first direction) and cross-sectional view  908  of  FIG. 9B  (taken along a second direction that is perpendicular to the first direction), a first etching process is performed to pattern the first dielectric layer  110 . The first etching process forms one or more sidewalls  110   s  of the first dielectric layer  110  that define a plurality of openings  902  extending through the first dielectric layer  110 . In some embodiments, the plurality of openings  902  may respectively have a substantially rectangular shape as viewed from a top-view. In other embodiments, the plurality of openings  902  may respectively have a substantially circular shape, a substantially square shape, or the like, as viewed from a top-view. In some embodiments, the first etching process may be performed by exposing the first dielectric layer  110  to a first etchant  904  according to a first mask  906 . In some embodiments, the first etchant  904  may comprise a dry etchant (e.g., a reactive ion etching (RIE) etchant, a plasma etchant, or the like). In some embodiments, the first etchant  904  may have an etching chemistry comprising one or more of fluorine (F), tetrafluoromethane (CF 4 ), ozone ( 02 ), or octafluorocyclobutane (C 4 F 8 ), or the like. In some embodiments, the first mask  906  may comprise a photosensitive material (e.g., photoresist), a hard mask, or the like. 
     As shown in cross-sectional view  1000  of  FIG. 10 , a capacitor stack  1001  is formed over the first dielectric layer  110  and within the plurality of openings  902 . In some embodiments, the capacitor stack  1001  may be formed by forming a lower electrode layer  1002  along the one or more sidewalls  110   s  and along an upper surface of the first dielectric layer  110 , by forming a capacitor dielectric layer  1004  along sidewalls and an upper surface of the lower electrode layer  1002 , by forming an upper electrode layer  1006  along sidewalls and an upper surface of the capacitor dielectric layer  1004 , and by forming a dielectric layer  1008  along sidewalls and an upper surface of the upper electrode layer  1006 . In some embodiments, the lower electrode layer  1002 , the capacitor dielectric layer  1004 , the upper electrode layer  1006 , and the dielectric layer  1008  may be formed by a plurality of deposition processes (e.g., a PVD process, a CVD process, a PE-CVD process, an ALD process, or the like). 
     As shown in cross-sectional view  1100  of  FIG. 11 , one or more capping layers  1102  are formed over the capacitor stack  1001 . In some embodiments, the one or more capping layers  1102  may comprise an anti-reflective layer. In some embodiments, a masking layer  1104  is formed over the one or more capping layers  1102 . A second mask  1106  is subsequently formed over the one or more capping layers  1102  and/or the masking layer  1104 . The second mask  1106  may be formed to directly overlie the plurality of openings  902  within the first dielectric layer  110 . In some embodiments, the masking layer  1104  and the one or more capping layers  1102  may respectively comprise a dielectric. For example, in some embodiments the one or more capping layers  1102  may comprise silicon oxynitride, while the masking layer  1104  may comprise silicon nitride. In some embodiments, the second mask  1106  may comprise a photosensitive material (e.g., photoresist), a hard mask, or the like. 
     As shown in cross-sectional view  1200  of  FIG. 12 , a second etching process is performed according to the second mask  1106 . The second etching process removes parts of the masking layer (e.g.,  1104  of  FIG. 11 ), the one or more capping layers (e.g.,  1102  of  FIG. 11 ), the dielectric layer (e.g.,  1008  of  FIG. 11 ), and the upper electrode layer (e.g.,  1006  of  FIG. 11 ) to define a masking layer  206 , a capping structure  118 , a dielectric  204 , and an upper electrode  116 . The second etching process also exposes an upper surface of the capacitor dielectric layer  1004 . In some embodiments, the second etching process etches the masking layer, the one or more capping layers, the dielectric layer, and the upper electrode layer to a second etchant  1202  according to the second mask  1106 . In some embodiments, the second etchant  1202  may comprise a dry etchant (e.g., a reactive ion etching (RIE) etchant, a plasma etchant, or the like). In some embodiments, the second etchant  1202  may have an etching chemistry comprising one or more tetrafluoromethane (CF 4 ), fluoroform (CHF 3 ), chlorine (Cl 2 ), nitrogen (N 2 ), argon (Ar), boron trichloride (BCl 3 ), or the like. 
     As shown in cross-sectional view  1300  of  FIG. 13 , a spacer structure  1302  is formed along horizontally extending surfaces of the capping structure  118  and the capacitor dielectric layer  1004  and also along sidewalls of the capping structure  118  and the upper electrode  116 . In some embodiments, the spacer structure  1302  comprises a first dielectric layer  1304  and a second dielectric layer  1306  over the first dielectric layer  1304 . The first dielectric layer  1304  and the second dielectric layer  1306  continuously extend between outermost sidewalls of the spacer structure  1302 . In some embodiments, the spacer structure  1302  may be formed by one or more deposition processes (e.g., a PVD process, a CVD process, a PE-CV process, or the like). In various embodiments, the spacer structure  1302  may comprise silicon nitride, silicon dioxide, silicon oxynitride, and/or the like. In some embodiments, the spacer structure  1302  is formed to a thickness that is in a range of between approximately 100 Å and approximately 1500 Å, between approximately 50 Å and approximately 1000 Å, between approximately 250 Å and approximately 7500 Å, approximately 500 Å, or other similar values. 
     As shown in cross-sectional view  1400  of  FIG. 14 , the spacer structure (e.g.,  1302  of  FIG. 13 ) is exposed to a third etchant  1402  during a third etching process. The third etchant removes the spacer structure (e.g.,  1302  of  FIG. 13 ) from horizontally extending surfaces. Removing the spacer structure (e.g.,  1302  of  FIG. 13 ) from the horizontally extending surfaces leaves a part of the spacer structure (e.g.,  1302  of  FIG. 13 ) along opposing sidewalls the capping structure  118  and the upper electrode  112  as a spacer  120  (e.g., a self-aligned spacer). In some embodiments, the third etchant  1402  may comprise a dry etchant (e.g., a reactive ion etching (RIE) etchant, a plasma etchant, or the like). In some embodiments, the third etchant  1402  may have an etching chemistry comprising one or more tetrafluoromethane (CF 4 ), cluoroform (CHF 3 ), chlorine (Cl 2 ), nitrogen (N 2 ), argon (Ar), boron trichloride (BCl 3 ), or the like. 
     In some embodiments, parts of the lower electrode layer (e.g.,  1002  of  FIG. 13 ) and the capacitor dielectric layer (e.g.,  1004  of  FIG. 13 ) are subsequently exposed to a fourth etchant according to the spacer  120  to define a lower electrode  112  and a capacitor dielectric  114  of a MIM capacitor structure  111 . In some embodiments, the fourth etchant may be a same etchant as the third etchant  1402  (e.g., as part of a continuous etching process that defines the spacer  120 ), while in other embodiments the fourth etchant may comprise an etchant that is separate and different than the third etchant  1402 . Since the lower electrode layer and the capacitor dielectric layer are etched according to the spacer  120 , the spacer  120  has an outermost sidewall that is substantially aligned with outermost sidewalls of the lower electrode  112  and the capacitor dielectric  114 . 
     By using the spacer  120  to define the lower electrode  112  the capacitor dielectric  114 , the lower electrode  112  can be formed to have a similar sized footprint as the upper electrode  116 . Furthermore, using the spacer  120  to define the lower electrode  112  allows for both the upper electrode  116  and the lower electrode  112  to be formed using a single photomask, thereby providing for a relatively low cost process to form the MIM capacitor structure  111  (e.g., compared to a process that uses separate photomasks to define upper and lower electrodes). Moreover, having the spacer  120  in place during the third etching process allows for the spacer  120  to cover sidewalls of the upper electrode  116  and to prevent conductive byproducts (e.g., from etching the lower electrode layer) from being re-deposited along sidewalls of the upper electrode  116 . By preventing conductive byproducts from being re-deposited along sidewalls of the upper electrode  116  the conductive byproducts cannot form a conductive path between the lower electrode  112  and the upper electrode  116 , thereby preventing electrical shorting between the lower electrode  112  and the upper electrode  116 . 
     As shown in cross-sectional view  1500  of  FIG. 15 , a second dielectric layer  212  is formed over the MIM capacitor structure  111  and the first dielectric layer  110 . In some embodiments, the second dielectric layer  212  may comprise an oxide, a low-k dielectric material, or the like. The second dielectric layer  212  may be formed by one or more deposition processes (e.g., a PVD process, a CVD process, a PE-CVD process, an ALD process, or the like). 
     As shown in cross-sectional view  1600  of  FIG. 16 , a fifth etching process is subsequently performed to form one or more upper interconnect openings  1602  within the second dielectric layer  212 . The one or more upper interconnect openings  1602  extend through the second dielectric layer  212 , the masking layer  206 , the capping structure  118 , and the dielectric  204  to expose an upper surface of the upper electrode  116 . In some embodiments, the fifth etching process may be performed by exposing the second dielectric layer  212  to a fifth etchant  1604  according to a third mask  1606 . In some embodiments, the fifth etchant  1604  may comprise a plasma etchant having an etching chemistry comprising one or more of fluorine (F), tetrafluoromethane (CF 4 ), ozone (O 2 ), or octafluorocyclobutane (C 4 F 8 ), or the like. In some embodiments, the third mask  1606  may comprise a photosensitive material (e.g., photoresist), a hard mask, or the like. 
     As shown in cross-sectional view  1700  of  FIG. 17 , an upper interconnect structure  122  is formed within the second dielectric layer  212 . In some embodiments, the upper interconnect structure  122  may be formed by forming a conductive material within the one or more upper interconnect openings  1602  etched into the second dielectric layer  212 . In some embodiments, the conductive material may be formed by way of a deposition process and/or a plating process (e.g., electroplating, electro-less plating, etc.). In various embodiments, the conductive material may comprise copper, aluminum, or the like. After forming the conductive material within the upper interconnect opening  1602 , a planarization process may be performed to remove excess of the conductive material from over the second dielectric layer  212  and to define an upper interconnect structure  122 . In some embodiments, the upper interconnect structure  122  may comprise an upper interconnect via  122   v  and an upper interconnect wire  122   w.    
       FIG. 18  illustrates a flow diagram of some embodiments of a method  1800  of forming an integrated chip having a high density MIM capacitor structure. 
     While the methods (e.g., methods  1800  and  3000 ) is illustrated and described herein as a series of acts or events, it will be appreciated that the illustrated ordering of such acts or events are not to be interpreted in a limiting sense. For example, some acts may occur in different orders and/or concurrently with other acts or events apart from those illustrated and/or described herein. In addition, not all illustrated acts may be required to implement one or more aspects or embodiments of the description herein. Further, one or more of the acts depicted herein may be carried out in one or more separate acts and/or phases. 
     At act  1802 , one or more lower interconnects are formed within a lower dielectric structure over a substrate.  FIG. 7  illustrates a cross-sectional view  700  of some embodiments corresponding to act  1802 . 
     At act  1804 , a first dielectric layer is formed over the lower dielectric structure.  FIG. 8  illustrates a cross-sectional view  800  of some embodiments corresponding to act  1804 . 
     At act  1806 , the first dielectric layer is patterned to form a plurality of openings.  FIGS. 9A-9B  illustrate cross-sectional views,  900  and  908 , of some embodiments corresponding to act  1806 . 
     At act  1808 , a lower electrode layer is formed over the first dielectric layer and within the plurality of openings.  FIG. 10  illustrates a cross-sectional view  1000  of some embodiments corresponding to act  1808 . 
     At act  1810 , a capacitor dielectric layer is formed onto the lower electrode layer.  FIG. 10  illustrates a cross-sectional view  1000  of some embodiments corresponding to act  1810 . 
     At act  1812 , an upper electrode layer is formed onto the capacitor dielectric layer.  FIG. 10  illustrates a cross-sectional view  1000  of some embodiments corresponding to act  1812 . 
     At act  1814 , one or more capping layers are formed over the upper electrode layer.  FIG. 11  illustrates a cross-sectional view  1100  of some embodiments corresponding to act  1814 . 
     At act  1816 , the one or more capping layers and the upper electrode layer are patterned outside of a mask to define a capping structure and an upper electrode.  FIGS. 11-12  illustrate cross-sectional views  1100 - 1200  of some embodiments corresponding to act  1816 . 
     At act  1818 , a spacer (e.g., a self-aligned spacer) is formed along opposing sides of the upper electrode and the capping structure.  FIGS. 13-14  illustrate cross-sectional views  1300 - 1400  of some embodiments corresponding to act  1818 . 
     At act  1820 , the lower electrode layer and the capacitor dielectric layer are patterned according to the spacer to define a lower electrode and a capacitor dielectric of a MIM capacitor structure.  FIG. 14  illustrates a cross-sectional view  1400  of some embodiments corresponding to act  1820 . 
     At act  1822 , a second dielectric layer is formed over the MIM capacitor structure.  FIG. 15  illustrates a cross-sectional view  1500  of some embodiments corresponding to act  1822 . 
     At act  1824 , an upper interconnect structure is formed to extend through the capping structure to contact the upper electrode.  FIGS. 16-17  illustrate cross-sectional views  1600 - 1700  of some embodiments corresponding to act  1824 . 
       FIGS. 19-29  illustrate cross-sectional views  1900 - 2900  of some alternative embodiments of a method of forming an integrated chip having a high density MIM capacitor structure. Although  FIGS. 19-29  are described in relation to a method, it will be appreciated that the structures disclosed in  FIGS. 19-29  are not limited to such a method, but instead may stand alone as structures independent of the method. 
     As shown in cross-sectional view  1900  of  FIG. 19 , one or more lower interconnects  104  are formed within a lower dielectric structure  106  formed over a substrate  102 . 
     As shown in cross-sectional view  2000  of  FIG. 20 , a first etch stop layer  108  is formed over the lower dielectric structure  106  and a first dielectric layer  110  is formed over the first etch stop layer  108 . 
     As shown in cross-sectional view  2100  of  FIG. 21A  (taken along a first direction) and cross-sectional view  2102  of  FIG. 21B  (taken along a second direction that is perpendicular to the first direction), a first etching process is performed to pattern the first dielectric layer  110 . The first etching process forms one or more sidewalls  110   s  of the first dielectric layer  110  that define a plurality of openings  902  extending through the first dielectric layer  110   
     As shown in cross-sectional view  2200  of  FIG. 22 , a capacitor stack  1001  is formed over the first dielectric layer  110  and within the plurality of openings  902 . In some embodiments, the capacitor stack  1001  may be formed by forming a lower electrode layer  1002  along the one or more sidewalls  110   s  and an upper surface of the first dielectric layer  110 , by forming a capacitor dielectric layer  1004  along sidewalls and an upper surface of the lower electrode layer  1002 , by forming an upper electrode layer  1006  along sidewalls and an upper surface of the capacitor dielectric layer  1004 , and by forming a dielectric layer  1008  along sidewalls and an upper surface of the upper electrode layer  1006 . 
     As shown in cross-sectional view  2300  of  FIG. 23 , one or more capping layers  1102  are formed over the capacitor stack  1001 . A second mask  2302  is subsequently formed over the one or more capping layers  1102 . The second mask  2302  may be formed to directly overlie the plurality of openings  902  within the first dielectric layer  110 . In some embodiments, the second mask  2302  may comprise a photosensitive material (e.g., photoresist), a hard mask, or the like. 
     As shown in cross-sectional view  2400  of  FIG. 24 , a second etching process is performed according to the second mask  2302 . The second etching process removes parts of the one or more capping layers (e.g.,  1102  of  FIG. 11 ), the dielectric layer (e.g.,  1008  of  FIG. 11 ), and the upper electrode layer (e.g.,  1006  of  FIG. 11 ) to define a capping structure  118 , a dielectric  204 , and an upper electrode  116 . The second etching process also exposes an upper surface of the capacitor dielectric layer  1004 . In some embodiments, the second etchant  2402  may comprise a dry etchant (e.g., a reactive ion etching (RIE) etchant, a plasma etchant, or the like). In some embodiments, the second etchant  2402  may have an etching chemistry comprising one or more tetrafluoromethane (CF 4 ), fluoroform (CHF 3 ), chlorine (Cl 2 ), nitrogen (N 2 ), argon (Ar), boron trichloride (BCl 3 ), or the like. 
     As shown in cross-sectional view  2500  of  FIG. 25 , a spacer structure  2502  is formed along horizontally extending surfaces of the capping structure  118  and the capacitor dielectric layer  1004  and also along sidewalls of the capping structure  118  and the upper electrode  116 . In some embodiments, the spacer structure  2502  comprises a first dielectric layer  2504  and a second dielectric layer  2506  over the first dielectric layer  2504 . The first dielectric layer  2504  and the second dielectric layer  2506  continuously extend between outermost sidewalls of the spacer structure  2502 . In some embodiments, the spacer structure  2502  is formed to a thickness that is in a range of between approximately 100 Å and approximately 1500 Å, between approximately 50 Å and approximately 1000 Å, or other similar values. 
     As shown in cross-sectional view  2600  of  FIG. 26 , a third mask  2602  is formed over the spacer structure  2502 . In some embodiments, the third mask  2602  may extend past outermost sidewalls of the upper electrode  116  and the capping structure  118 . In some embodiments, the third mask  2602  may extend a non-zero distance  506  past the outermost sidewalls of the upper electrode  116  and the capping structure  118 . In some embodiments, the non-zero distance  506  may be in a range of between approximately 50 Å and approximately 750 Å. In some embodiments, the third mask  2602  may be completely confined above a topmost surface of the spacer structure (e.g.,  2502  of  FIG. 26 ). In such embodiments, the third mask  2602  may have a bottommost surface that is over a topmost surface of the spacer structure (e.g.,  2502  of  FIG. 26 ). In some embodiments, the third mask  2602  may comprise a photosensitive material (e.g., photoresist), a hard mask, or the like. 
     As shown in cross-sectional view  2700  of  FIG. 27 , a third etching process is performed to expose the spacer structure (e.g.,  2502  of  FIG. 26 ) to a third etchant  2702  according to the third mask  2602 . The third etchant  2702  removes unmasked parts of the spacer structure (e.g.,  2502  of  FIG. 26 ) to define a spacer  120 . In some embodiments, parts of the lower electrode layer (e.g.,  1002  of  FIG. 26 ) and the capacitor dielectric layer (e.g.,  1004  of  FIG. 26 ) are subsequently exposed to a fourth etchant according to the spacer  120  to define a lower electrode  112  and a capacitor dielectric  114  of a MIM capacitor structure  111 . Since the lower electrode layer and the capacitor dielectric layer are etched according to the spacer  120 , the spacer  120  has an outermost sidewall that is substantially aligned with outermost sidewalls of the lower electrode  112  and the capacitor dielectric  114 . In some embodiments, the fourth etchant may be a same etchant as the third etchant  2702  (e.g., as part of a continuous etching process that defines the spacer  120 ), while in other embodiments the fourth etchant may comprise an etchant that is separate and different than the third etchant  2702   
     As shown in cross-sectional view  2800  of  FIG. 28 , a second dielectric layer  212  is formed over the MIM capacitor structure  111  and the first dielectric layer  110 . 
     As shown in cross-sectional view  2900  of  FIG. 29 , an upper interconnect structure  122  is subsequently formed within one or more upper interconnect openings  1602  within the second dielectric layer  212 . In some embodiments, the upper interconnect structure  122  may comprise an upper interconnect via  122   v  and an upper interconnect wire  122   w.    
       FIG. 30  illustrates a flow diagram of some alternative embodiments of a method  3000  of forming an integrated chip having a high density MIM capacitor structure. 
     At act  3002 , one or more lower interconnects are formed within a lower dielectric structure over a substrate.  FIG. 19  illustrates a cross-sectional view  1900  of some embodiments corresponding to act  3002 . 
     At act  3004 , a first dielectric layer is formed over the lower dielectric structure.  FIG. 20  illustrates a cross-sectional view  2000  of some embodiments corresponding to act  3004 . 
     At act  3006 , the first dielectric layer is patterned to form a plurality of openings.  FIGS. 21A-21B  illustrate cross-sectional views  2100 - 2102  of some embodiments corresponding to act  3006 . 
     At act  3008 , a lower electrode layer is formed over the first dielectric layer and within the plurality of openings.  FIG. 22  illustrates a cross-sectional view  2200  of some embodiments corresponding to act  3008 . 
     At act  3010 , a capacitor dielectric layer is formed onto the lower electrode layer.  FIG. 22  illustrates a cross-sectional view  2200  of some embodiments corresponding to act  3010 . 
     At act  3012 , an upper electrode layer is formed onto the capacitor dielectric layer.  FIG. 22  illustrates a cross-sectional view  2200  of some embodiments corresponding to act  3012 . 
     At act  3014 , one or more capping layers are formed over the upper electrode layer.  FIG. 23  illustrates a cross-sectional view  2300  of some embodiments corresponding to act  3014 . 
     At act  3016 , the one or more capping layers and the upper electrode layer are patterned outside of to a first mask to define a capping structure and an upper electrode.  FIGS. 23-24  illustrate cross-sectional views  2300 - 2400  of some embodiments corresponding to act  3016 . 
     At act  3018 , a spacer structure is formed over and along opposing sides of the upper electrode and the capping structure.  FIG. 25  illustrates a cross-sectional view  2500  of some embodiments corresponding to act  3018 . 
     At act  3020 , a second mask is formed over the spacer structure.  FIG. 26  illustrates a cross-sectional view  2600  of some embodiments corresponding to act  3020 . 
     At act  3022 , the spacer structure, the lower electrode layer, and the capacitor dielectric layer are patterned according to the second mask to define a lower electrode and a capacitor dielectric of a MIM capacitor structure.  FIG. 27  illustrates a cross-sectional view  2700  of some embodiments corresponding to act  3022 . 
     At act  3024 , a second dielectric layer is formed over the MIM capacitor structure.  FIG. 28  illustrates a cross-sectional view  2800  of some embodiments corresponding to act  3024 . 
     At act  3026 , an upper interconnect structure is formed to extend through the capping structure to contact the upper electrode.  FIG. 29  illustrate cross-sectional views  2900  of some embodiments corresponding to act  3026 . 
     Accordingly, in some embodiments, the present disclosure relates to a method of forming a MIM device having upper and lower electrodes with footprints having similar sizes (e.g., having sizes that are within approximately 10% of one another). 
     In some embodiments, the present disclosure relates to a method of forming a capacitor structure that includes forming a capacitor dielectric layer over a lower electrode layer; forming an upper electrode layer over the capacitor dielectric layer; etching the upper electrode layer to define an upper electrode and to expose a part of the capacitor dielectric layer; forming a spacer structure over horizontally extending surfaces of the upper electrode layer and the capacitor dielectric layer and also along sidewalls of the upper electrode; etching the spacer structure to remove the spacer structure from over the horizontally extending surfaces of the upper electrode layer and the capacitor dielectric layer and to define a spacer; and etching the capacitor dielectric layer and the lower electrode layer according to the spacer to define a capacitor dielectric and a lower electrode. In some embodiments, the method may further include forming one or more capping layers over the upper electrode layer; etching the one or more capping layers to define a capping structure; and forming the spacer structure over a horizontally extending surface of the capping structure and along sidewalls of the capping structure. In some embodiments, the method may further include forming a dielectric layer over the upper electrode layer and between sidewalls of the upper electrode layer prior to forming the one or more capping layers, a first etching process that etches the upper electrode layer to define the upper electrode also removes a part of the dielectric layer. In some embodiments, material from the lower electrode layer is re-deposited onto sidewalls of the spacer and the capacitor dielectric layer during etching of the lower electrode layer. In some embodiments, the spacer structure includes a first dielectric and a second dielectric arranged along sidewalls and a lower surface of the first dielectric. In some embodiments, an outermost sidewall of the lower electrode is aligned with an outermost surface of the spacer. In some embodiments, the method further includes forming one or more lower interconnects within a lower dielectric structure over a substrate; forming a first dielectric layer over the lower dielectric structure; and patterning the first dielectric layer to define a plurality of openings that extend through the first dielectric layer to expose the one or more lower interconnects, the lower electrode layer, the upper electrode layer, and the capacitor dielectric layer being formed within the plurality of openings and over the first dielectric layer. In some embodiments, a patterning process that etches the lower electrode layer also removes a part of the first dielectric layer. In some embodiments, the plurality of openings respectively have a substantially rectangular shape as viewed from a top-view of the first dielectric layer. In some embodiments, the plurality of openings are arranged in an array including a first plurality of openings arranged in a first column extending in a first direction and further including a second plurality of openings arranged in a first row extending in a second direction that is perpendicular to the first direction. In some embodiments, the upper electrode covers between approximately 90% and approximately 95% of the lower electrode. 
     In other embodiments, the present disclosure relates to a method of forming a capacitor structure that includes forming one or more lower interconnects within a lower dielectric structure over a substrate; forming a first dielectric layer over the lower dielectric structure; forming a plurality of openings extending through the first dielectric layer to expose the one or more lower interconnects; forming a capacitor stack over the first dielectric layer and within the plurality of openings, the capacitor stack having a capacitor dielectric layer between a lower electrode layer and an upper electrode layer; forming one or more capping layers over the upper electrode layer; etching the one or more capping layers and the upper electrode layer to define a capping structure over an upper electrode; forming a spacer along sidewalls of the capping structure and the upper electrode, the spacer having an outermost surface that extends from the capacitor dielectric layer to a top of the spacer; and etching the capacitor dielectric layer and the lower electrode layer according to the spacer to define a capacitor dielectric over a lower electrode. In some embodiments, the method further includes forming a second dielectric layer onto the first dielectric layer and along a sidewall of the first dielectric layer; and forming one or more additional interconnects within the second dielectric layer, the one or more additional interconnects laterally separated from the lower electrode by the first dielectric layer and the second dielectric layer. In some embodiments, the method further includes patterning the second dielectric layer and the capping structure to form an upper interconnect opening that exposes the upper electrode; and forming a conductive material within the upper interconnect opening. In some embodiments, the lower electrode is completely confined below the spacer and the upper electrode. In some embodiments, the spacer continuously extends along a closed path around outermost sidewalls of the upper electrode. 
     In yet other embodiments, the present disclosure relates to a metal-insulator-metal (MIM) capacitor structure that includes one or more lower interconnects disposed within a lower dielectric structure over a substrate; a first dielectric layer over the lower dielectric structure, the first dielectric layer having sidewalls defining a plurality of openings extending through the first dielectric layer; a lower electrode arranged along the sidewalls and over an upper surface of the first dielectric layer; a capacitor dielectric arranged along sidewalls and an upper surface of the lower electrode; an upper electrode arranged along sidewalls and an upper surface of the capacitor dielectric; and a spacer along opposing outermost sidewalls of the upper electrode, the spacer having an outermost surface that extends from a lowermost surface of the spacer to a top of the spacer, the outermost surface being substantially aligned with an outermost sidewall of the lower electrode. In some embodiments, the outermost sidewall of the lower electrode is substantially aligned with a sidewall of the first dielectric layer. In some embodiments, the MIM capacitor structure further includes a capping structure over the upper electrode, the spacer covering sidewalls of the upper electrode and the capping structure; and the spacer having a first dielectric and a second dielectric, the first dielectric having a horizontally extending segment separating the second dielectric from the capacitor dielectric and a vertically extending segment separating the second dielectric from the upper electrode and the capping structure. In some embodiments, a collective footprint of both the upper electrode and the spacer is substantially equal to a footprint of the lower electrode. 
     The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.