Abstract:
The invention encompasses methods of forming DRAM constructions, methods of forming capacitor constructions, DRAM constructions, and capacitor constructions. The invention includes a method in which a) a first layer is formed over a node location; b) a semiconductive material masking layer is formed over the first layer; c) an opening is formed through the semiconductive material masking layer and the first layer to the node location; d) an upwardly open capacitor storage node layer is formed within the opening; e) a storage node is formed from the masking layer and the storage node layer; and f) a capacitor dielectric layer and a capacitor plate are formed over the storage node. The invention also includes a capacitor structure comprising: a) an insulative layer over a substrate; b) a polysilicon layer over the insulative layer; c) an opening extending through the polysilicon layer and the insulative layer to a node, the opening comprising an upper portion and a lower portion, the upper portion comprising a first minimum cross-sectional dimension and the lower portion comprising a second minimum cross-sectional dimension which is narrower than the first minimum cross-sectional dimension, the opening further comprising a step at an interface of the upper and lower portions; d) a spacer over the step; e) a storage node layer over the spacer, polysilicon layer and the node; and f) a dielectric layer and a cell plate layer capacitively coupled to the storage node layer.

Description:
RELATED PATENT DATA 
     This patent resulted from a divisional application of U.S. patent application Ser. No. 08/951,855, filed on Oct. 16, 1997. 
    
    
     TECHNICAL FIELD 
     This invention pertains to semiconductor capacitor constructions and to methods of forming semiconductor capacitor constructions. The invention is thought to have particular significance in application to methods of forming dynamic random access memory (DRAM) cell structures and to DRAM cell structures. 
     BACKGROUND OF THE INVENTION 
     A commonly used semiconductor memory device is a DRAM cell. A DRAM cell generally consists of a capacitor coupled through a transistor to a bitline. A continuous challenge in the semiconductor industry is to increase DRAM circuit density. Accordingly, there is a continuous effort to decrease the size of memory cell components. A limitation on the minimal size of cell components is impacted by the resolution of a photolithographic etch during fabrication of the components. Although this resolution is generally improving, at any given time there is a minimum photolithographic feature dimension obtainable in a fabrication process. It would be desirable to form DRAM components having at least some portion with a cross-sectional dimension of less than a given minimum capable photolithographic feature dimension. 
     Another continuous trend in the semiconductor industry is to minimize processing steps. Accordingly, it is desirable to utilize common steps for the formation of separate DRAM components. For instance, it is desirable to utilize common steps for the formation of DRAM capacitor structures and DRAM bitline contacts. 
     SUMMARY OF THE INVENTION 
     The invention includes a number of methods and structures pertaining to semiconductor circuit technology, including: methods of forming DRAM memory cell constructions; methods of forming capacitor constructions; methods of forming capacitor and bitline constructions; DRAM memory cell constructions; and capacitor constructions. For instance, the invention encompasses a method wherein a first layer is a formed over a node location; a semiconductive material masking layer is formed over the first layer; an opening is etched through the semiconductive material masking layer and first layer to the node location; an upwardly open capacitor storage node layer is formed within the opening and in electrical connection with the masking layer; a capacitor storage node is formed comprising the masking layer and the storage node layer; and a capacitor dielectric layer and outer capacitor plate are formed over the capacitor storage node. 
     As another example, the invention encompasses a capacitor structure which includes an insulative layer over a substrate and a semiconductive material layer over the insulative layer. The capacitor structure further includes an opening which extends through the semiconductive material layer and the insulative layer to an electrical node, and which comprises an upper portion and a lower portion, the upper portion comprising a first minimum cross-sectional dimension and the lower portion comprising a second minimum cross-sectional dimension which is narrower than the first minimum cross-sectional dimension, the opening further comprising a step at an interface of the upper and lower portions. The capacitor further comprises a spacer over the step, and a storage node layer over the spacer, semiconductive material layer and electrical node; wherein the storage node layer physically contacts the semiconductive material layer, the spacer, and the electrical node. Additionally, the capacitor comprises a dielectric layer and a cell plate layer capacitively coupled to the storage node layer. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the invention are described below with reference to the following accompanying drawings. 
     FIG. 1 is a schematic cross-sectional process view of a semiconductor wafer fragment at a preliminary step of a processing method in accordance with a method of the present invention. 
     FIG. 2 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that of FIG.  1 . 
     FIG. 3 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that of FIG.  2 . 
     FIG. 4 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that of FIG.  3 . 
     FIG. 5 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that of FIG.  4 . 
     FIG. 6 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that of FIG.  5 . 
     FIG. 7 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that of FIG.  6 . 
     FIG. 8 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that of FIG.  7 . 
     FIG. 9 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that of FIG.  8 . 
     FIG. 10 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that of FIG.  9 . 
     FIG. 11 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that of FIG.  10 . 
     FIG. 12 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that of FIG.  11 . 
     FIG. 13 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that of FIG.  12 . 
     FIG. 14 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that of FIG.  13 . 
     FIG. 15 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that of FIG. 10 processed according to a second embodiment of the present invention. 
     FIG. 16 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that of FIG.  15 . 
     FIG. 17 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that of FIG. 8 processed according to a third embodiment of the present invention. 
     FIG. 18 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that of FIG.  17 . 
     FIG. 19 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that of FIG.  18 . 
     FIG. 20 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that of FIG.  19 . 
     FIG. 21 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that of FIG.  20 . 
     FIG. 22 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that of FIG.  22 . 
     FIG. 23 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that of FIG. 8 processed according to a fourth embodiment of the present invention. 
     FIG. 24 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that of FIG.  23 . 
     FIG. 25 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that of FIG.  24 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     This disclosure of the invention is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8). 
     A method of forming DRAM cells of the present invention is described with reference to FIGS. 1-25, with FIGS. 1-14 pertaining to a first embodiment of the invention, FIGS. 15-16 pertaining to a second embodiment of the invention, FIGS. 17-22 pertaining to a third embodiment of the invention, and FIGS. 23-25 pertaining to a fourth embodiment of the invention. 
     Referring first to FIG. 1, a semiconductor wafer fragment  10  is illustrated at a preliminary step of a processing sequence of a method of the present invention. Wafer fragment  10  comprises a semiconductive material  12 , field oxide regions  14 , and a thin gate oxide layer  16 . A polysilicon layer  18 , silicide layer  20  and silicon oxide layer  22  are formed over gate oxide layer  16 . Silicide layer  20  comprises a refractory metal silicide, such as tungsten silicide, and polysilicon layer  18  typically comprises polysilicon doped with a conductivity enhancing dopant. 
     Referring next to FIG. 2, polysilicon layer  18 , silicide layer  20  and silicon oxide layer  22  are etched to form wordlines  24  and  26 . Between wordlines  24  and  26  are defined node locations  25 ,  27  and  29 , with wordlines  26  comprising transistor gates which electrically connect node locations  25 ,  27 , and  29 . Node location  27  is laterally between node locations  25  and  29 , and may lie along an imaginary straight line extending between node locations  25  and  29 , or may be offset from such imaginary straight line. Node locations  25 ,  27  and  29  typically comprise diffusion regions formed within semiconductive material  12  by ion implanting conductivity enhancing dopant into the material  12 . Such ion implanting may occur after patterning wordlines  24  and  26 , utilizing wordlines  24  and  26  as masks. Alternatively, the diffusion regions may be formed prior to deposition of one or more of layers  18 ,  20  and  22  (shown in FIG.  1 ). In yet other alternative methods, the diffusion regions may be formed after formation of doped polysilicon adjacent the regions by out-diffusion of conductivity enhancing dopant from the doped polysilicon. 
     For the above-discussed reasons, node locations  25 ,  27 , and  29  need not be electrically conductive at the preliminary step of FIG.  2 . Nodes  25 ,  27  and  29  could be conductive at the step of FIG. 2 if formed by ion implanting of dopant into semiconductive material  12 . Alternatively, nodes  25 ,  27  and  29  may be substantially non-conductive at the preliminary step of FIG. 2 in, for example, embodiments in which nodes  25 ,  27  and  29  are ultimately doped by out-diffusion of dopant from a conductively doped layer. 
     Referring to FIGS. 3 and 4, a nitride layer  28  is provided over wordlines  24  and  26 , and subsequently etched to form nitride spacers  30  laterally adjacent wordlines  24  and  26 . 
     Referring to FIG. 5, an overlying oxide layer  32  is provided over wordlines  24  and gates  26 , and subsequently a borophosphosilicate glass (BPSG) layer  34  is provided over oxide layer  32 . Oxide layer  32  functions to prevent the diffusion of phosphorus from the BPSG into underlying materials. As is readily apparent to persons of ordinary skill in the art, other insulative materials may be substituted for the BPSG of layer  34 . If such other insulative materials are substituted, it may be desirable to dispense with formation of oxide layer  32 . 
     BPSG layer  34  is planarized by, for example, chemical-mechanical polishing to form a planar upper surface  35 . After the planarization of BPSG layer  34 , a semiconductive material masking layer  36  is provided over BPSG layer  34 , with masking layer  36  comprising a bottom surface  37  adjacent upper surface  35 . Preferably, masking layer  36  will comprise undoped polysilicon deposited to a thickness of from about 6000 Angstroms to about 8000 Angstroms. Formation of patterned polysilicon layer  36  may comprise, for example, provision of a patterned photoresist layer over an unpatterned polysilicon layer, followed by a conventional etch of the polysilicon to transfer a pattern from the patterned photoresist layer to the polysilicon. In the shown cross-sectional view, masking layer  36  comprises masking layer segments  41 ,  42  and  43 , with segment  42  laterally between segments  41  and  43 . Gaps  44  and  45  are between segments  41  and  42 , and  42  and  43 , respectively. Gaps  44  and  45  overlie nodes  25  and  29 , while segment  42  overlies node  27 . 
     Referring to FIG. 6, first and second openings  38  and  40  are etched through gaps  44  and  45  (shown in FIG.  5 ), respectively, and into BPSG layer  34 , typically using a timed anisotropic dry etch. Openings  38  and  40  comprise bases  60  and  62 , respectively, which are preferably above nodes  25  and  29 . Accordingly, openings  38  and  40  preferably do not extend to nodes  25  and  29 . 
     Referring to FIG. 7, a layer  64  is provided over segments  42  and within openings  38  and  40 . Layer  64  is provided to a thickness which less than completely fills openings  38  and  40 . Layer  64  thus narrows openings  38  and  40 . Preferably, openings  38  and  40  will comprise a minimum internal dimension approximately equal to the minimum photolithographic feature dimension obtainable during fabrication of the openings. Accordingly, after formation of layer  64 , openings  38  and  40  will be narrowed to comprise an internal dimension less than such minimum capable photolithographic feature dimension. 
     Layer  64  may comprise either an insulative material or a conductive material. A preferred material is the insulative material silicon oxide. An example method for forming a silicon oxide layer  64  is chemical vapor deposition utilizing tetraethylorthosilicate (TEOS). 
     Referring to FIG. 8, layer  64  is anisotropically etched to leave spacers  66  within openings  38  and  40 . Methods for anisotropically etching layer  64  are known to persons of ordinary skill in the art. An example method for anisotropically etching the preferred silicon oxide layer  64  includes a fluorocarbon-based dry etch. 
     Spacers  66  comprise upper surfaces  67 . In the shown preferred embodiment, upper surfaces  67  are below bottom surfaces  37  of segments  42 . As will be recognized by persons of ordinary skill in the art, the location of upper surface  67  relative to bottom surface  37  may be adjusted by varying a number of parameters, including: 1) the thickness of layer  64  (shown in FIG.  7 ); 2) the length of time of the anisotropic etch used to etch layer  64 ; and 3) the depth of openings  38  and  40 . 
     After formation of spacers  66 , third and fourth openings  68  and  70 , respectively, are formed by appropriate anisotropic etching. Third opening  68  extends from base  60  (shown in FIG. 6) of first opening  38  to electrical node  25 . Fourth opening  70  extends from base  62  (shown in FIG. 6) of second opening  40  to electrical node  29 . Openings  68  and  70  comprise internal cross-sectional dimensions about equal to the narrowed cross-sectional dimensions of openings  38  and  40  resulting after deposition of layer  64  (shown in FIG.  7 ). Openings  68  and  70  are therefore narrower than openings  38  and  40 . 
     First opening  38  and third opening  68  together comprise a first capacitor opening  72 . Similarly, second opening  40  and fourth opening  70  together comprise a second capacitor opening  74 . 
     Referring to first capacitor opening  72 , the opening comprises a step  76  at the interface of first opening  38  and third opening  68 , with step  76  corresponding to a remaining portion of base  60  (shown in FIG. 6) of original opening  38 . In the lateral cross-sectional view of FIG. 8, it appears that there are a pair of laterally opposing steps  76  within opening  72 . In some embodiments of the invention, there may be distinct laterally opposing steps  76  within opening  38 . However, in preferred embodiments of the invention, opening  38  will comprise a circular horizontal cross-sectional shape. In such preferred embodiments, the apparent laterally opposing steps  76  will, in fact, be sections of a continuous step  76  within opening  38 . 
     Referring to second capacitor opening  74 , this opening, analogously to first capacitor opening  72 , comprises a step  78  at an interface of second opening  40  and fourth opening  70 , with step  78  corresponding to base  62  (shown in FIG. 6) of original opening  40 . 
     Spacers  66  within capacitor openings  72  and  74  are atop steps  76  and  78 , respectively. 
     Referring to FIG. 9, a storage node layer  80  is provided over masking layer  36 , within capacitor openings  72  and  74 , and in contact with segments  41 ,  42  and  43 . Storage node layer  80  preferably comprises a rugged polysilicon, such as a polysilicon selected from the group consisting of hemispherical grain polysilicon and cylindrical grain polysilicon, and is preferably provided to a thickness of from about 300 Angstroms to about 700 Angstroms. 
     Referring to FIG. 10, a patterned photoresist layer  82  is provided over capacitor openings  72  and  74 , and over portions of masking layer segments  42 , leaving exposed portions of the masking layer segments (not shown). Subsequently, the exposed portions are removed. Removal of an exposed portion of segment  42  (shown in FIG. 9) forms a fifth opening  84  over node  27 . Fifth opening  84  divides segment  42  (shown in FIG. 9) into a first portion  86  and a second portion  88 . Opening  84  comprises a base  90  above node  27 . 
     Adjacent opening  84  are defined two storage nodes  81  and  83 . First storage node  81  comprises storage node layer  80 , segment  41  and portion  86 . Second storage node  83  comprises storage node layer  80 , segment  43  and portion  88 . Also, as storage node layer  80  overlies and contacts spacers  66 , storage nodes  81  and  83  may comprise spacers  66 , particularly if spacers  66  comprise electrically conductive material. Preferably, if spacers  66  are incorporated into storage nodes  81  and  83 , spacers  66  will be electrically isolated from wordlines  24  and  26 . 
     As discussed above, segment  42  (shown in FIG. 9) will preferably comprise polysilicon. Methods of etching such preferred segments are known to persons of ordinary skill in the art, and comprise, for example, anisotropic dry etching. 
     Referring to FIG. 11, a capacitor dielectric layer  92  and a cell plate layer  94  are provided over segments  41  and  43 , over portions  81  and  83 , and within capacitor openings  72  and  74 . Dielectric layer  92  comprises an electrically insulative material, such as silicon nitride or a composite of silicon nitride and silicon dioxide. Cell plate layer  94  comprises an electrically conductive material, such as polysilicon doped to concentration of greater than 1×10 19  ions/cm 3 . Layers  92  and  94  may be formed by conventional methods. 
     The provision of layers  92  and  94  forms a first capacitor structure  100  and a second capacitor structure  102 . First capacitor structure  100  comprises storage node  81 , dielectric layer  92  and cell plate layer  94 . Second capacitor  102  comprises storage node  83  dielectric layer  92  and cell plate layer  94 . 
     After formation of layers  92  and  94 , a patterned photoresist layer  96  is formed over openings  72  and  74 , leaving an exposed area  98  within fifth opening  84  and over node  27 . 
     Referring to FIG. 12, exposed portions of cell plate layer  94  and dielectric layer  92  within area  98  are removed. 
     After removal of the exposed portions of cell plate layer  94  and dielectric layer  92 , photoresist blocks  96  are removed and an insulative layer  104  is formed atop wafer fragment  10 . Subsequently, patterned photoresist layer  106  is formed over insulative layer  104 , leaving an exposed gap  108  over node  27 . 
     Referring to FIG. 13, a bitline contact opening  110  is etched through insulative layer  104 , through layer  34 , through oxide  32 , and to node  27 . 
     After formation of bitline contact opening  110 , photoresist layer  106  (shown in FIG. 12) is removed and a bitline contact layer  112  is formed over insulative material layer  104  and within opening  110 . The portion of bitline contact material  112  within opening  110  forms a bitline contact  114 . 
     Bitline contact layer  112  comprises a conductive material, such as tungsten. Methods for forming layer  112  are known to persons of ordinary skill in the art, and include, for example, sputter deposition of tungsten. 
     Referring to FIG. 14, bitline contact layer  112  is removed from over insulative layer  104 , and a bitline  116  is formed over layer  104  and in electrical contact with bitline contact  114 . Bitline  116  preferably comprises a conductive material, such as aluminum, and may be formed by conventional methods. 
     The structure shown in FIG. 14 comprises a DRAM array including capacitors  100  and  102  electrically connected through transistor gates  26  to bitline contact  114  and ultimately to bitline  116 . The DRAM array of FIG. 14 actually comprises two DRAM cell structures, with capacitor  100  and a transistor gate  26  comprising a first DRAM cell structure; and capacitor  102  and a transistor gate  26  comprising a second DRAM cell structure. 
     A second embodiment method of the present invention is described with reference to FIGS. 15 and 16. In the embodiment of FIGS. 15-16, similar numbering to that of the embodiment of FIGS. 1-14 is utilized, with differences indicated by the suffix “a”, or by different numbers. 
     Referring to FIG. 15, a wafer fragment  10   a  is shown at a step subsequent to the processing step of FIG. 10. A patterned photoresist layer  122  is formed over and within capacitor openings  72  and  74 . Unlike the embodiment of FIGS. 1-14, the embodiment of FIG. 15 comprises cavities  120  etched into layer  34 , under segments  41  and  43 , and under portions  86  and  88 . Methods of forming cavities  120  are known to persons of ordinary skill in the art. An example process of forming cavities  120  in a BPSG layer  34  is a wet isotropic etch of oxide selective to polysilicon. Such etch undercuts beneath polysilicon segments  41  and  43 , and beneath polysilicon portions  86  and  88 . 
     Referring to FIG. 16, the FIG. 15 wafer segment is illustrated after subsequent processing analogous to the processing of FIGS. 11-14. Specifically, a dielectric layer  92  and cell plate layer  94  are provided within capacitor openings  72  and  74  (shown in FIG.  15 ), over masking layer segments  41  and  43 , over portions  86  and  88 , and within cavities  120  to form capacitor structures  100   a  and  102   a.  An insulative layer  104  and a bitline  116  are formed over capacitor structures  100   a  and  102   a,  and a bitline contact  114  is formed between capacitor structures  100   a  and  102   a.  A first storage node  81   a  comprises storage node layer  80 , segment  41  and portion  86 . A second storage node  83   a  comprises storage node layer  80 , segment  43  and portion  88 . 
     The capacitors  100   a  and  102   a  of FIG. 16 advantageously differ from the capacitors  100  and  102  of FIG. 14 in that dielectric layer  92  and cell plate layer  94  wrap around storage nodes  81   a  and  83   a,  and within cavities  120 . Accordingly, the capacitive area of capacitors  100   a  and  102   a  is increased relative to the capacitive area of capacitors  100  and  102  of FIG.  14 . 
     A third embodiment of the invention is described with reference to FIGS. 17-22. In the embodiment of FIGS. 17-22, similar numbering to that of the embodiment of FIGS. 1-14 is utilized, with differences indicated by the suffix “b”, or by different numbers. 
     Referring to FIG. 17, a wafer fragment  10   b  is shown at a processing step subsequent to that of FIG. 8. A fifth opening  84   b  is formed over electrical node  27 , dividing segment  42  (shown in FIG. 8) into portions  86   b  and  88   b.  Note that the embodiment of FIGS. 17-22 differs from that of FIGS. 1-14 in that fifth opening  84   b  (shown in FIG. 17) is formed prior to deposition of storage node layer  80   b,  while fifth opening  84  (shown in FIG. 10) is formed after deposition of storage node layer  80   b.  After formation of fifth opening  84   b,  a rugged polysilicon storage node layer  80   b  is formed over segments  41  and  43 , over portions  86   b  and  88   b,  and over upper surface  35  of insulative layer  34 , as well as within capacitor openings  72  and  74 . A first storage node  81   b  comprises storage node layer  80   b,  segment  41  and portion  86   b.  A second storage node  83   b  comprises storage node layer  80   b,  segment  43  and portion  88   b.    
     Referring to FIG. 18, polysilicon layer  80   b  is subjected to an anisotropic dry or wet etch. Such etch removes layer  80   b  from over segments  41  and  43 , portions  86   b  and  88   b,  and upper surface  35  of layer  34 . Also, the etch transfers roughness from rugged polysilicon layer  80   b  to upper surface  35 , upper surfaces of segments  41  and  43 , and upper surfaces of portions  86   b  and  88   b.  Removal of layer  80   b  from upper surface  35  in gap  84   b  electrically isolates portion  86   b  from portion  88   b,  and thus isolates storage node  81   b  from storage node  83   b.    
     Referring to FIG. 19, a dielectric layer  92  and cell plate layer  94  are provided over storage nodes  81   b  and  83   b,  and over upper surface  35  of layer  34 . Storage node  81   b,  dielectric layer  92 , and cell plate layer  94  together comprise a capacitor construction  10   b.  Similarly, storage node  83   b,  dielectric layer  92  and cell plate layer  94  together comprise a capacitor construction  102   b.    
     A patterned photoresist layer  96  is provided over layers  92  and  94 . Patterned photoresist  96  comprises a gap over node  27  and within fifth opening  84   b  (shown in FIG. 18) leaving an exposed area  98  over electrical node  27 . 
     Referring to FIG. 20, cell plate layer  94  and dielectric layer  92  are removed from exposed area  98  (shown in FIG.  19 ). Subsequently, an insulative layer  104  is formed over capacitor structures  100   b  and  102   b.  A patterned photoresist layer  106  is formed over insulative layer  104 , leaving a gap  108  over electrical node  27 . 
     Referring to FIG. 21, layers  104 ,  34  and  32  are etched through gap  108  to form a bitline contact opening  110  extending through layers  104 ,  34  and  32  to electrical node  27 . After formation of bitline contact opening  110 , a bitline contact layer  112  is formed over layer  104  and within opening  110 . A portion of bitline contact layer  112  within opening  110  is a bitline contact  114 . 
     Referring to FIG. 22, bitline contact layer  112  is removed from over layer  104 . Subsequently, a bitline  116  is formed over layer  104  and in electrical contact with bitline contact  114 . 
     A fourth embodiment of the method of the present invention is described with reference to FIGS. 23-25. The fourth embodiment is effectively a combination of the second and third embodiments described above. Identical numbering is utilized in FIGS. 23-25 as was utilized in FIGS. 1-14, with differences indicated by the suffix “c”, or by different numerals. 
     Referring to FIG. 23, wafer fragment  10   c  is shown at a processing step subsequent to that of FIG. 8. A patterned photoresist layer  122  is formed over and within capacitor openings  72  and  74 . Subsequently, cavities  120  are formed beneath the segments  41  and  43 , and beneath portions  86  and  88 . 
     Referring to FIG. 24, photoresist layer  122  is removed and storage node layer  80  is formed over segments  41  and  43 , over portions  86  and  88 , within capacitor openings  72  and  74 , and within cavities  120 . A first storage node  81   c  comprises storage node layer  80 , segment  41  and portion  86 . A second storage node  83   c  comprises storage node layer  80 , segment  43  and portion  88 . 
     Referring to FIG. 25, subsequent processing analogous to that of FIGS. 9-14 has occurred to form capacitor structures  100   c  and  102   c,  bitline contact  114 , and bitline  116 . 
     The above-described DRAMs and capacitors of the present invention can be implemented into monolithic integrated circuitry, including microprocessors. 
     To aid in interpretation of the claims that follow, the term “semiconductive substrate” is defined to mean any construction comprising semiconductive material, including, but not limited to, bulk semiconductive materials such as a semiconductive wafer (either alone or in assemblies comprising other materials thereon), and semiconductive material layers (either alone or in assemblies comprising other materials). The term “substrate” refers to any supporting structure, including, but not limited to, the semiconductive substrates described above. 
     In compliance with the statute, the invention has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.