METAL-INSULATOR-METAL (MIM) CAPACITOR MODULE

Abstract

A metal-insulator-metal (MIM) capacitor module is provided. The MIM capacitor module includes a bottom electrode base formed in a lower metal layer, a bottom electrode conductively coupled to the bottom electrode base, a planar insulator formed over the bottom electrode, and a top electrode formed in an upper metal layer over the insulator. The bottom electrode includes a cup-shaped bottom electrode component and a bottom electrode fill component formed in an interior opening defined by the cup-shaped bottom electrode component.

Claims

1. A metal-insulator-metal capacitor module, comprising: a bottom electrode base formed in a lower metal layer; a bottom electrode conductively coupled to the bottom electrode base and comprising: a cup-shaped bottom electrode component; a bottom electrode fill component formed in an interior opening defined by the cup-shaped bottom electrode component; a planar insulator formed over the bottom electrode; and a top electrode formed in an upper metal layer over the planar insulator.

2. The metal-insulator-metal capacitor module of claim 1, wherein the planar insulator has a uniform vertical thickness across a full lateral width of the planar insulator.

3. The metal-insulator-metal capacitor module of claim 1, wherein the planar insulator has a uniform vertical thickness across a full lateral width of the planar insulator in a first lateral direction and in a second lateral direction perpendicular to the first lateral direction.

4. The metal-insulator-metal capacitor module of claim 1, wherein: the bottom electrode is formed in a dielectric region; the planar insulator is formed on a planarized insulator support surface including (a) a planarized top surface of the cup-shaped bottom electrode component, (b) a planarized top surface of the bottom electrode fill component, and (c) planarized top surface areas of the dielectric region on opposite sides of the bottom electrode; and the planar insulator extends laterally across and beyond a full lateral width of the bottom electrode, such that the planar insulator extends over the planarized top surface areas of the dielectric region on opposite sides of the bottom electrode.

5. The metal-insulator-metal capacitor module of claim 1, wherein: the bottom electrode is formed in a dielectric region; the planar insulator extends laterally across and beyond a full lateral width of the bottom electrode, such that the planar insulator extends over portions of the dielectric region laterally adjacent the bottom electrode; and the planar insulator has a uniform vertical thickness across a full lateral width of the planar insulator.

6. The metal-insulator-metal capacitor module of claim 1, wherein: the bottom electrode is formed in a dielectric region; the planar insulator extends laterally across and beyond a full lateral width of the bottom electrode in a first lateral direction and in a second lateral direction perpendicular to the first lateral direction, such that the planar insulator extends over portions of the dielectric region laterally adjacent the bottom electrode in both the first and second lateral directions; the planar insulator has a uniform vertical thickness across a full lateral width of the planar insulator in both the first and second lateral directions.

7. The metal-insulator-metal capacitor module of claim 1, wherein the cup-shaped bottom electrode component is formed on the bottom electrode base.

8. The metal-insulator-metal capacitor module of claim 1, wherein the planar insulator is formed on a planarized insulator support surface including a planarized top surface of the cup-shaped bottom electrode component and a planarized top surface of the bottom electrode fill component.

9. The metal-insulator-metal capacitor module of claim 1, wherein: the bottom electrode is formed in a dielectric region between the lower metal layer and the upper metal layer; the metal-insulator-metal capacitor module comprises: a bottom electrode connection element formed in the upper metal layer; and a bottom electrode contact formed in the dielectric region between the lower metal layer and the upper metal layer; wherein the bottom electrode connection element is conductively connected to the bottom electrode base through the bottom electrode contact.

10. The metal-insulator-metal capacitor module of claim 9, wherein: the bottom electrode contact and the cup-shaped bottom electrode component are formed from a conformal metal; and the bottom electrode fill component is formed from a fill metal different than the conformal metal.

11. The metal-insulator-metal capacitor module of claim 10, wherein the conformal metal comprises tungsten, and the fill metal comprises titanium nitride.

12. The metal-insulator-metal capacitor module of claim 1, wherein the lower metal layer comprises a lower interconnect layer; and the upper metal layer comprises an upper interconnect layer.

13. The metal-insulator-metal capacitor module of claim 1, wherein: the lower metal layer comprises a silicided polysilicon layer, wherein the bottom electrode base formed in the lower metal layer comprises a metal silicide region formed on a polysilicon region; and the upper metal layer comprises a first metal interconnect layer.

14. An integrated circuit structure, comprising: an interconnect structure comprising: a lower interconnect element formed in a lower metal layer; an upper interconnect element formed in an upper metal layer; and an interconnect via conductively connected between the lower interconnect element and the upper interconnect element; and a metal-insulator-metal capacitor module comprising: a bottom electrode base formed in the lower metal layer; a bottom electrode conductively coupled to the bottom electrode base and comprising: a cup-shaped bottom electrode component; a bottom electrode fill component formed in an interior opening defined by the cup-shaped bottom electrode component; a planar insulator formed over the bottom electrode; and a top electrode formed in the upper metal layer; wherein the cup-shaped bottom electrode component and the interconnect via are formed from a common conformal metal.

15. The integrated circuit structure of claim 14, wherein the planar insulator has a uniform vertical thickness across a full lateral width of the planar insulator.

16. The integrated circuit structure of claim 14, wherein the planar insulator has a uniform vertical thickness across a full lateral width of the planar insulator in a first lateral direction and in a second lateral direction perpendicular to the first lateral direction.

17. The integrated circuit structure of claim 14, wherein: the bottom electrode is formed in a dielectric region; the planar insulator is formed on a planarized insulator support surface including (a) a planarized top surface of the cup-shaped bottom electrode component, (b) a planarized top surface of the bottom electrode fill component, and (c) planarized top surface areas of the dielectric region on opposite sides of the bottom electrode; and the planar insulator extends laterally across and beyond a full width of the bottom electrode, such that the planar insulator extends over the planarized top surface areas of the dielectric region on opposite sides of the bottom electrode.

18. The integrated circuit structure of claim 14, wherein: the bottom electrode is formed in a dielectric region; the planar insulator extends laterally across and beyond a full lateral width of the bottom electrode, such that the planar insulator extends over portions of the dielectric region laterally adjacent the bottom electrode; and the planar insulator has a uniform vertical thickness across a full lateral width of the planar insulator.

19. The integrated circuit structure of claim 14, wherein: a top surface of the cup-shaped bottom electrode component and a bottom electrode fill component define a planar bottom electrode top surface; and the planar insulator is formed on the planar bottom electrode top surface.

20. The integrated circuit structure of claim 14, wherein: the metal-insulator-metal capacitor module comprises a bottom electrode contact providing a conductive connection between the bottom electrode base and a bottom electrode connection element formed in the upper metal layer; and wherein the interconnect via, the bottom electrode contact, and the bottom electrode are formed in a dielectric region between the lower metal layer and the upper metal layer.

21. A method of forming a metal-insulator-metal capacitor module in an integrated circuit structure, the method comprising: forming a lower metal layer including a bottom electrode base; depositing a dielectric region over the lower metal layer; patterning and etching the dielectric region to form a tub opening and a bottom electrode contact opening; depositing a conformal metal to concurrently form (a) a cup-shaped bottom electrode component in the tub opening and (b) a bottom electrode contact in the bottom electrode contact opening, wherein each of the cup-shaped bottom electrode component and the bottom electrode contact is conductively coupled to the bottom electrode base; depositing a fill metal to form a bottom electrode fill component in an interior opening defined by the cup-shaped bottom electrode component; performing a planarization process to define a planarized insulator support surface including a planarized top surface of the cup-shaped bottom electrode component and a planarized top surface of the bottom electrode fill component; forming a planar insulator on the planarized insulator support surface; and forming an upper metal layer including (a) a top electrode over the planar insulator and (b) a bottom electrode connection element conductively connected to the bottom electrode contact.

22. The method of claim 21, wherein the planar insulator has a uniform vertical thickness across a full lateral width of the planar insulator.

23. The method of claim 21, wherein: the planarized insulator support surface formed by the planarization process includes the planarized top surface of the cup-shaped bottom electrode component, the planarized top surface of the bottom electrode fill component, and planarized top surface areas of the dielectric region on opposite sides of the bottom electrode; and the planar insulator extends laterally across and beyond a full lateral width of the bottom electrode, such that the planar insulator extends over the planarized top surface areas of the dielectric region on opposite sides of the bottom electrode.

24. The method of claim 21, comprising forming the planar insulator such that: the planar insulator extends laterally across and beyond a full lateral width of the bottom electrode, such that the planar insulator extends over portions of the dielectric region laterally adjacent the bottom electrode; and the planar insulator has a uniform vertical thickness across a full lateral width of the planar insulator.

25. The method of claim 21, comprising: depositing an insulator layer on the planarized insulator support surface; depositing an upper metal layer on an insulator layer region of the insulator layer; and patterning and etching the upper metal layer and underlying insulator layer region to define the top electrode and the planar insulator underlying the top electrode, wherein lateral surfaces of the top electrode are self-aligned with lateral surfaces of the planar insulator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Example aspects of the present disclosure are described below in conjunction with the figures, in which:

[0054] FIGS. 1A-1F are cross-sectional side views showing an example prior art process for forming an example MIM capacitor module;

[0055] FIG. 2A is a cross-sectional side view an example MIM capacitor module formed between two metal interconnect layers in an integrated circuit structure, according to one example;

[0056] FIG. 2B is a cross-sectional side view an example MIM capacitor module formed between a silicided polysilicon layer and a first metal interconnect layer in an integrated circuit structure, according to one example;

[0057] FIGS. 3-12 are cross-sectional side views showing an example process of forming an integrated circuit structure including the example MIM capacitor module shown in FIG. 2A along with an example interconnect structure;

[0058] FIG. 13 is a flowchart showing an example method of forming an example MIM capacitor module and interconnect structure in an integrated circuit structure, according to one example; and

[0059] FIG. 14 is a flowchart showing an example method of forming an example integrated circuit structure including an example MIM capacitor module and nearby interconnect structure, according to one example.

[0060] It should be understood the reference number for any illustrated element that appears in multiple different figures has the same meaning across the multiple figures, and the mention or discussion herein of any illustrated element in the context of any particular figure also applies to each other figure, if any, in which that same illustrated element is shown.

DETAILED DESCRIPTION

[0061] The present disclosure provides an MIM capacitor module formed between (and including) two metal layers in an integrated circuit structure. The MIM capacitor module includes a bottom electrode base formed in a lower metal layer M.sub.x, a bottom electrode conductively coupled to the bottom electrode base, a planar insulator formed over the bottom electrode, a top electrode formed in an upper metal layer M.sub.x+1 over the insulator, a bottom electrode connection element formed in the upper metal layer M.sub.x+1, and a bottom electrode contact conductively connecting the bottom electrode connection element to the bottom electrode base. The bottom electrode includes a cup-shaped bottom electrode component and a bottom electrode fill component formed in an interior opening defined by the cup-shaped bottom electrode component.

[0062] The bottom electrode may be formed by a damascene process, including forming a tub opening, depositing a conformal metal layer (e.g., tungsten) that forms the cup-shaped bottom electrode component in the tub opening, depositing a fill metal (e.g., titanium nitride) to form the bottom electrode fill component in the interior opening of the cup-shaped bottom electrode component, and performing a planarization process (e.g., CMP process) to (a) remove upper portions of the conformal metal layer and fill metal and (b) define a planarized insulator support surface at the top of the bottom electrode.

[0063] The planar insulator may then be formed on the planarized insulator support surface, and may have a uniform thickness across a full lateral width of the insulator, which may provide an improved capacitor breakdown voltage as compared with certain conventional capacitors. In addition, by forming the bottom electrode from refractory metals, e.g., tungsten and titanium nitride, the top surface of the bottom electrode that interfaces the planar insulator may be free of hillocks that are common in certain conventional capacitors (e.g., capacitors using an aluminum bottom electrode), which may provide a higher and more consistent capacitor breakdown voltage as compared with such conventional capacitors. Also, the top electrode and the bottom electrode may each have a substantial thickness, e.g., a thickness of at least 4000 Å, which may provide improved performance in particular applications (e.g., RF applications) as compared with certain conventional capacitors having a thinner top electrode and/or bottom electrode.

[0064] As mentioned above, the MIM capacitor module is formed between (and including) two metal layers, in particular a lower metal layer M.sub.x (in which the bottom electrode base is formed) and an upper metal layer M.sub.x+1 (in which the top electrode and bottom electrode connection element are formed). As used herein, a “metal layer,” for example in the context of the lower metal layer M.sub.x and upper metal layer M.sub.x+1, may comprise any metal or metalized layer or layers, including:

[0065] (a) a metal interconnect layer, e.g., comprising aluminum, copper, or other metal formed by a damascene process or deposited by a subtractive patterning process (e.g., deposition, patterning, and etching of a metal layer), or

[0066] (b) a silicided polysilicon layer including a number of silicided polysilicon structures (i.e., polysilicon structures having a metal silicide layer formed thereon), for example a silicided polysilicon gate of a metal-oxide-semiconductor field-effect transistor (MOSFET).

[0067] For example, as shown in FIG. 2A, an MIM capacitor module may be constructed between two adjacent metal interconnect layers M.sub.x and M.sub.x+1 at any depth in an integrated circuit structure. As another example, as shown in FIG. 2B, an MIM capacitor module may be constructed between a silicided polysilicon layer and a first metal interconnect layer (commonly referred to as the metal-1 layer), wherein the silicided polysilicon layer defines the lower metal layer M.sub.x where x=0 (i.e., M.sub.0) and the first metal interconnect layer (Metal-1 layer) defines the upper metal layer M.sub.x+1 (i.e., M.sub.1).

[0068] FIG. 2A is a cross-sectional side view an example MIM capacitor module 200a formed between (and including portions of) two metal interconnect layers M.sub.x and M.sub.x+1 in an integrated circuit structure, according to one example. The example MIM capacitor module 200a includes (a) a bottom electrode base 202 formed in a lower metal interconnect layer M.sub.x, (b) a bottom electrode 204 conductively coupled to the bottom electrode base 202, (c) a planar insulator 206 formed over the bottom electrode 204, and (d) a top electrode 208 formed in an upper metal interconnect layer M.sub.x+1 over the planar insulator 206. The MIM capacitor module 200a also includes a bottom electrode connection element 214 formed in the upper metal interconnect layer M.sub.x+1, and a bottom electrode contact 216 conductively connecting the bottom electrode connection element 214 to the bottom electrode base 202.

[0069] Metal interconnect layers M.sub.x and M.sub.x+1 may be formed from aluminum, copper, or other suitable interconnect metal. Thus, bottom electrode base 202 formed in metal interconnect layer M.sub.x, and top electrode 208 and bottom electrode connection element 214 formed in the upper metal interconnect layer M.sub.x+1, may be formed from aluminum, copper, or other suitable interconnect metal.

[0070] The bottom electrode 204 includes (a) a cup-shaped bottom electrode component 220 formed in a tub opening 221 in a dielectric region 230, e.g., an oxide inter-metal dielectric (IMD) region, and (b) a bottom electrode fill component 222 formed in an interior opening 224 defined by the cup-shaped bottom electrode component 220. The bottom electrode 204 may be formed using a damascene process, as described in more detail below with reference to FIGS. 4A-4B through 7A-7B. The cup-shaped bottom electrode component 220 may be formed from a conformal metal, e.g., tungsten. The bottom electrode fill component 222 may be formed from a “fill metal” that may be different than the conformal metal that forms the cup-shaped bottom electrode component 220. For example, the fill metal forming the bottom electrode fill component 222 may comprise TiN or other refractory metal different than the conformal metal forming the cup-shaped bottom electrode component 220.

[0071] In some examples, the bottom electrode contact 216 and the cup-shaped bottom electrode component 220 may be formed simultaneously by deposition of tungsten or other conformal metal, as discussed below with reference to FIG. 5. In some examples, an adhesive layer 226 (e.g., a TiN layer with a thickness in the range of 50-300 Å) is deposited prior to the conformal metal (forming bottom electrode contact 216 and cup-shaped bottom electrode component 220) to improve adhesion between the conformal metal and dielectric region 230, in particular in the tub opening 221.

[0072] In some examples, the bottom electrode contact 216 is formed as a via, and may also be referred to as a bottom electrode via. For example, as discussed below with reference to FIGS. 4A-5, the bottom electrode contact 216 may be formed as a via, simultaneous with interconnect vias formed in the dielectric region 230 (IMD region) at locations distinct from the MIM capacitor module 200a.

[0073] As shown in FIG. 2A, the planar insulator 206 may be formed on a planarized insulator support surface 240. The planarized insulator support surface 240, which may be formed by a chemical mechanical planarization (CMP) or other planarization process, includes a planarized top surface 234 of the cup-shaped bottom electrode component 220, a planarized top surface 236 of the bottom electrode fill component 222, and planarized top surface areas 238a and 238b of the dielectric region 230 on opposite lateral sides of the bottom electrode 204 (in the x-direction, or in both the x-direction and y-direction).

[0074] The planarized insulator support surface 240 may free of metal hillocks, as the bottom electrode 204 is formed from refractory metals (e.g., tungsten and titanium nitride) which resist the formation of hillocks, unlike the aluminum bottom electrode of the example prior art MIM capacitor module 10 shown in FIG. 1F discussed above. Forming the planar insulator 206 on a surface free of hillocks may provide a higher and more consistent capacitor breakdown voltage, e.g., as compared with a conventional capacitor having a bottom electrode including hillocks.

[0075] The surface roughness of the planarized insulator support surface 240 may depend on the specific process parameters implemented (e.g., CMP process parameters). In some examples, the planarized insulator support surface 240 has a root-mean-square (RMS) surface roughness of less than 50 Å. In some examples, the planarized insulator support surface 240 has an RMS surface roughness of less than 20 Å.

[0076] The planar insulator 206 may be formed directly on the planarized insulator support surface 240. The width W.sub.ins of the planar insulator 206 in the x-direction may be coextensive with the width W.sub.te of the overlying top electrode 208, as a result of an anisotropic metal etch extending through both the top electrode 208 and planar insulator 206, e.g., as shown in FIG. 11 discussed below.

[0077] In some examples, e.g., as shown in FIG. 2A, the top electrode 208 and planar insulator 206 are formed with a greater width (W.sub.te, W.sub.ins) than the underlying bottom electrode 204 in the x-direction, such that the planar insulator 206 extends across and beyond the full lateral width of the bottom electrode 204 and onto the planarized top surface areas 238a and 238b of dielectric region 230 on opposite sides of the bottom electrode 204 in the x-direction. In other words, the planar insulator 206 extends across the planarized top surface 234 of the cup-shaped bottom electrode component 220, the planarized top surface 236 of the bottom electrode fill component 222, and the planarized top surface areas 238a and 238b of the dielectric region 230. In some examples, the planar insulator 206 extends laterally across the full lateral width of the bottom electrode 204 in both the x-direction and y-direction, and additionally extends over portions of the dielectric region 230 on all lateral sides of the bottom electrode 204, such that a perimeter of the planar insulator region 206 surrounds a perimeter of the bottom electrode 204, from a top view.

[0078] The planar insulator 206 has a uniform thickness T.sub.ins across the full lateral width W.sub.ins of the planar insulator 206. For example, in some examples the thickness T.sub.ins of the insulator layer 206 varies by less than 10% across the full lateral width W.sub.ins of the planar insulator 206. In some implementations the thickness T.sub.ins of the insulator layer 206 varies by less than 5%, or even less than 1%, across the full lateral width W.sub.ins of the planar insulator 206.

[0079] This uniform thickness T.sub.ins across the full lateral width W.sub.ins of the planar insulator 206 may provide an increased and predictable breakdown voltage for the resulting MIM capacitor module 200, e.g., as compared with a capacitor having a partially etched thickness or otherwise varying thickness, e.g., the prior art MIM capacitor 10 shown in FIG. 1F and discussed above.

[0080] Further, by forming the bottom electrode 204 between two metal layers M.sub.x and M.sub.x+1 the bottom electrode 204 may have a thickness T.sub.be extending across the full thickness of the dielectric region 230 between the metal layers M.sub.x and M.sub.x+1. In addition, by forming the top electrode 208 from the metal interconnect layer M.sub.x+1, the top electrode 208 may have a thickness T.sub.te defined by the thickness of the metal interconnect layer M.sub.x+1. Thus, the bottom electrode thickness T.sub.be and top electrode thickness T.sub.te may be sufficient to provide target performance characteristics for various applications (e.g., including RF applications), as compared with certain conventional capacitors having a thinner top electrode and/or bottom electrode. In some examples, the bottom electrode thickness T.sub.be may be at least 4000 Å, and the top electrode thickness T.sub.te may be at least 4000 Å.

[0081] FIG. 2B is a cross-sectional side view an example MIM capacitor module 200b formed between (and including portions of) a silicided polysilicon layer and a first metal interconnect layer (commonly referred to as the metal-1 layer), according to one example. In this example, the silicided polysilicon layer defines a lower metal layer M.sub.0 (i.e., lower metal layer M.sub.x where x=0) and the first metal interconnect layer (Metal-1) defines an upper metal layer M.sub.1.

[0082] MIM capacitor module 200b is similar to MIM capacitor module 200a shown in FIG. 2A and discussed above, except the MIM capacitor module 200b is formed between the silicided polysilicon layer M.sub.0 and first metal interconnect layer M.sub.1, rather than between two metal interconnect layers M.sub.x and M.sub.x+1.

[0083] MIM capacitor module 200b includes (a) a bottom electrode base 203 formed in the silicided polysilicon layer M.sub.0, (b) a bottom electrode 204 including a cup-shaped bottom electrode component 220 and a bottom electrode fill component 222, (c) a planar insulator 206 formed over the bottom electrode 204, (d) a top electrode 208 and a bottom electrode connection element 214 formed in the first metal interconnect layer M.sub.1, and (e) a bottom electrode contact 216 conductively connecting the bottom electrode connection element 214 to the bottom electrode base 203. The bottom electrode 204 and bottom electrode contact 216 are formed in dielectric region 232, e.g., a pre-metal dielectric (PMD) region.

[0084] As shown in FIG. 2B, the bottom electrode base 203 is formed by a silicided polysilicon structure including a metal silicide layer 252 formed on a top surface of a polysilicon structure 250. The metal silicide layer 252 may comprise any suitable metal silicide layer, for example titanium silicide (TiSi2), cobalt silicide (CoSi2), or nickel silicide (NiSi), having a thickness in the range of 100-300 Å or other suitable thickness. The cup-shaped bottom electrode component 220 and bottom electrode contact 216 may be formed on the metal silicide layer 252. The metal silicide layer 252 provides a conductive connection between the bottom electrode 204 and the bottom electrode contact 216.

[0085] FIGS. 3-12 are cross-sectional side views showing an example process for forming an example integrated circuit structure 300 including the example MIM capacitor module 200a of FIG. 2A along with a nearby interconnect structure 302, according to one example.

[0086] First, as shown in FIG. 3, a lower metal interconnect layer M.sub.x is formed over a dielectric region 304, e.g., a pre-metal dielectric (PMD) region or inter-metal dielectric (IMD) region. Metal layer M.sub.x may be formed from aluminum, copper, or other suitable metal. Metal layer M.sub.x may be deposited, patterned, and etched to form (a) the bottom electrode base 202 for the MIM capacitor module 200a and (b) a lower interconnect element 306. Alternatively, the bottom electrode base 202 and lower interconnect element 306 may be formed by a damascene process. Each of bottom electrode base 202 and lower interconnect element 306 may comprise a wire or other laterally elongated structure (e.g., elongated in the y-axis direction), or a discrete pad (e.g., having a square, circular, or substantially square or circular shape in the x-y plane), or any other suitable shape and structure.

[0087] A resist strip may be performed to remove remaining portions of the photomask used for patterning the metal layer M.sub.x. An IMD region 230 may be formed over metal layer M.sub.x, e.g., by performing an oxide deposition (e.g., using high density plasma (HDP) and PECVD processes) followed by a CMP process to planarize the oxide.

[0088] Next, as shown in FIG. 4A (cross-sectional side view) and corresponding FIG. 4B (top view), the IMD region 230 is patterned and etched (e.g., using a plasma etch) to concurrently form (a) at least one interconnect via opening 310 for various interconnect structures, (b) a bottom electrode contact opening 312, and (c) the tub opening 221 for forming the bottom electrode 204 of the MIM capacitor module 200. The interconnect via opening 310 and bottom electrode contact opening 312 may each be formed as a narrow via opening with a lateral diameter or width W.sub.via. In contrast, the tub opening 221 may have a substantially larger width (x-direction) and/or length (y-direction) than the narrow via openings 310 and 312. The shape and dimensions of the tub opening 221 may be selected based on various parameters, e.g., for effective manufacturing of the MIM capacitor module 200 (e.g., effective deposition of the bottom electrode materials (e.g., tungsten and TiN) into the tub opening 221) and/or for desired performance characteristics of the resulting MIM capacitor module 200. In some examples, the tub opening 221 may have a square or rectangular shape from a top view, e.g., as shown in FIG. 4B. In other examples, the tub opening 221 may have a circular or oval shape from the top view.

[0089] As noted above, an x-direction width W.sub.tub and/or y-direction length L.sub.tub of the tub opening 221 may be substantially larger than the width W.sub.Via of each via opening. For example, in some embodiments, the width W.sub.tub and/or length L.sub.tub of the tub opening 221 is at least twice as large as the width W.sub.Via of each via opening. In particular embodiments, the width W.sub.tub and/or length L.sub.tub of the tub opening 221 is at least five time as large as the width W.sub.Via of each via opening. In some examples, the width W.sub.Via of each via opening is in the range of 0.1-0.5 μm, whereas the width W.sub.tub and length L.sub.tub of the tub opening 221 are each the range of 1-100 μm.

[0090] After the etch to create the openings 310, 312, and 221, any remaining photoresist material may be removed by a resist strip.

[0091] Next, as shown in FIG. 5, adhesive layer 226 (e.g., comprising titanium nitride, TiN) is deposited over the integrated circuit structure 300 and into the openings 310, 312, and 221, e.g., with a thickness in the range of 50-300 Å. A conformal metal layer 320, e.g., tungsten (W), is then deposited over adhesive layer 226, e.g., by Chemical Vapor Deposition (CVD) deposition, with a thickness in the range of 1000-5000 Å. As shown, the conformal metal layer 320 (a) fills the interconnect via opening 310 to form an interconnect via 332, (b) fills the bottom electrode contact opening 312 to form the bottom electrode contact 216, and (c) partially fills the tub opening 221 to form the cup-shaped bottom electrode component 220 in the tub opening 221. The cup-shaped bottom electrode component structure 220 defines an interior opening 324. The interconnect via 332, bottom electrode contact 216, and cup-shaped bottom electrode component 220 are further processed as discussed below, including a CMP process shown in FIG. 7A, which defines a final form of each respective element 332, 216, and 220.

[0092] The deposited conformal metal layer 320 layer may have high tensile stresses, due to inherent material properties of the conformal metal, e.g., tungsten. As a result, a deposition thickness above about 5000 Å (e.g., a thickness of 7000 Å) may result in a cracking or peeling of the conformal metal layer 320, or a warping or breakage of the underlying silicon wafer (not shown), e.g., during a subsequent CMP process.

[0093] Next, as shown in FIG. 6, a fill metal layer 330 is deposited over the integrated circuit structure 300 and extending down into the interior opening 324 of the cup-shaped bottom electrode component structure 220. The fill metal layer 330 may deposited with sufficient thickness to fill the interior opening 324 at least to the top of the adjacent dielectric region 230. The fill metal layer 330 may be deposited by a reactive PVD or CVD process without generating hillocks, which may provide an increased breakdown voltage for the resulting MIM capacitor module 200a, as compared with prior art designs that enable or encourage hillock formation on the capacitor bottom electrode (and/or other capacitor components), e.g., as discussed above regarding the example prior art capacitor shown in FIG. 1F.

[0094] In some examples, the fill metal layer 330 comprises titanium nitride (TiN) or other refractory metal (different from the conformal metal of the conformal metal layer 320) that has inherent compressive stresses (e.g., for a layer thickness of less than 1 μm). The inherent compressive stresses of the fill metal layer 330 may counteract the inherent tensile stresses of the underlying conformal metal layer 320 (e.g., tungsten layer), to thereby reduce the risk of inter-layer peeling, silicon wafer breakage, or other mechanical failure. In another example, the fill metal layer 330 is formed by aluminum, which may provide reduced resistance for the resulting bottom electrode 204, as described in relation to FIG. 2A, but may introduce the possibility of hillock formation.

[0095] Next, as shown in FIG. 7A (cross-sectional side view) and corresponding FIG. 7B (top view), a planarization process (e.g., CMP process) is performed to remove upper portions of the fill metal layer 330, the conformal metal layer 320, and adhesive layer 226, and thereby define the final form of the interconnect via 332, bottom electrode contact 216, cup-shaped bottom electrode component 220, and bottom electrode fill component 222. The planarization process may be designed to stop on the dielectric region 230. As discussed above, the cup-shaped bottom electrode component 220 and the bottom electrode fill component 222 collectively define the bottom electrode 204 of the MIM capacitor module 200a.

[0096] The planarization process (e.g., CMP process) defines a polished, planarized insulator support surface 240 for supporting the planar insulator 206, which is formed as discussed below. As shown in FIG. 7A, the planarized insulator support surface 240 includes a planarized top surface 234 of the cup-shaped bottom electrode component 220, a planarized top surface 236 of the bottom electrode fill component 222, and planarized top surface areas 238a, 238b of the dielectric region 230 on opposite sides of the bottom electrode 204. The planarized insulator support surface 240 provides a smooth, planarized surface free of hillocks, which is suitable for forming the planar insulator 206 thereon, as discussed below. For example, the planarized top surface 234 of the cup-shaped bottom electrode component 220 and the planarized top surface 236 of the bottom electrode fill component 222 provide smooth, planarized surfaces of refractory metals (e.g., tungsten and titanium nitride, as discussed above) that are free of hillocks, suitable for forming the planar insulator 206 thereon.

[0097] Next, as shown in FIG. 8, an insulator layer 350 is deposited over the structure 300. The insulator layer 350 may comprise silicon nitride (Si.sub.3N.sub.4, κ˜7) deposited with a thickness T.sub.ins in the range of 400-600 Å, for example by a PECVD deposition process. In other examples, the insulator layer 350 may comprise silicon oxide (SiO.sub.2) or a high-k dielectric material, e.g., Al.sub.2O.sub.3 (κ˜10), Ta.sub.2O.sub.5 (κ˜25), HfO.sub.2 (κ˜22), or ZrO.sub.2 (κ˜35), e.g., deposited by a PECVD deposition process or an ALD (atomic layer deposition) process.

[0098] Next, as shown in FIG. 9, the insulator layer 350 is patterned and etched to leave an insulator layer region 354 over the bottom electrode 204. The insulator layer region 354 extends laterally across the full lateral width of the bottom electrode 204, in the x-direction, and additionally extends over a portion of the dielectric region 230 on each lateral side of the bottom electrode 204. In some examples, insulator layer region 354 extends laterally across the full lateral width of the bottom electrode 204, in both the x-direction and y-direction, and additionally extends over portions of the dielectric region 230 on all lateral sides of the bottom electrode 204, such that a perimeter of the insulator layer region 354 surrounds a perimeter of the bottom electrode 204, from a top view.

[0099] The insulator layer 350 may be etched using a relatively simple dielectric etch, in contrast with prior art processes that involve a difficult top electrode metal etch. As shown, the thickness T.sub.ins of the insulator layer 350 remains uniform across the full lateral width (x-direction) of the insulator layer region 354.

[0100] An upper metal interconnect layer M.sub.x+1 is them formed over the integrated circuit structure 300. First, as shown in FIG. 10, an upper metal layer 360, e.g., aluminum comprising aluminum, copper, or other suitable metal, is deposited over the dielectric region 230 and the remaining portion of insulator layer region 354.

[0101] Next, as shown in FIG. 11, a photoresist layer is deposited and patterned to form a photomask 364 including a first photomask element 364a for forming an upper interconnect element 370, as discussed below), a second photomask element 364b (for forming the bottom electrode connection element 214, as discussed below), and a third photomask element 364c (for forming the top electrode 208 of the MIM capacitor module 200, as discussed below). As shown, a width W.sub.te_resist of the third photomask element 364c may be larger than a width W.sub.be of the bottom electrode 204 but smaller than the width W.sub.ins_layer of the insulator layer region 354, such that the subsequent metal etch to form the top electrode 208 (see FIG. 12, discussed below) self-aligns the lateral edges (in the x-direction) of the top electrode 208 with the underlying planar insulator 206 resulting from insulator layer region 354, while also preventing any etching of the bottom electrode 204.

[0102] FIG. 12 shows the results of the metal etch through the photomask 364 shown in FIG. 11, and after removal of the photomask 364, e.g., by a resist strip process. The etch may be selective to etch through portions of the upper metal layer 360 and underlying insulator layer region 354 not covered by the photomask 364 (see FIG. 11), but stop in the dielectric region 230, e.g., at a depth of 500-1000 Å into the dielectric region 230. As shown, the etch forms (a) the upper interconnect element 370 in contact with the interconnect via 332, (b) the bottom electrode connection element 214 in contact with the bottom electrode contact 216, and (c) the top electrode 208 over a remaining portion of the insulator layer region 354, which defines the planar insulator 206. As shown, the lateral edges of the top electrode 208 are aligned with the underlying planar insulator 206, as a result of the metal etch.

[0103] In the illustrated example, the planar insulator 206 extends laterally across the full lateral width W.sub.be of the bottom electrode 204, in the x-direction, and additionally extends over a portion of the dielectric region 230 on each lateral side of the bottom electrode 204 (in the x-direction). Thus, the width W.sub.ins of planar insulator 206 extends over the planarized top surface 234 of the cup-shaped bottom electrode component 220, the planarized top surface 236 of the bottom electrode fill component 222, and the planarized top surface areas 238a and 238b of the dielectric region 230 on opposite sides of the bottom electrode 204. Thus, the width W.sub.ins of planar insulator 206 is larger than the width W.sub.be of the bottom electrode 204. In some examples, the planar insulator 206 extends laterally across the full lateral width of the bottom electrode 204 in both the x-direction and y-direction, and additionally extends over portions of the dielectric region 230 on all lateral sides of the bottom electrode 204, such that a perimeter of the planar insulator region 206 surrounds a perimeter of the bottom electrode 204, from a top view.

[0104] By extending across the full lateral width of the bottom electrode 204, the planar insulator protects the underlying bottom electrode 204 from the metal etch of the upper metal layer 360. As discussed above, the insulator layer 206 has a uniform thickness T.sub.ins across the full lateral width W.sub.ins of the planar insulator 206 (in the x-direction, or in both the x-direction and y-direction). For example, in some examples the thickness T.sub.ins of the insulator layer 206 varies by less than 10%, less than 5%, or less than 1% across the full lateral width W.sub.ins of the planar insulator 206 (in the x-direction, or in both the x-direction and y-direction).

[0105] In some examples, FIG. 12 shows the completed of MIM capacitor module 200a. After forming the MIM capacitor module 200a, the process may continue with construction of additional interconnect structures, e.g., by forming further metal interconnect layers and/or dielectric layers.

[0106] FIG. 13 is a flowchart showing an example method 1300 of forming an example MIM capacitor module in an integrated circuit structure, according to one example. At 1302, a lower metal layer M.sub.x is formed, including a bottom electrode base. In one example, the lower metal layer M.sub.x comprises a lower interconnect metal layer (e.g., comprising aluminum). In another example, the lower metal layer M.sub.x comprises a silicided polysilicon layer. At 1304, a dielectric region (e.g., an oxide region) is deposited over the lower metal layer M.sub.x and planarized, for example, by a CMP process.

[0107] Next, as indicated by the dashed line box in FIG. 13, a damascene process may be performed at 1306-1312 to form a bottom electrode of the MIM capacitor module. First, at 1306, the dielectric region is patterned and etched to form a tub opening and a bottom electrode contact opening. Next, at 1308, a conformal metal (e.g., tungsten) is deposited to concurrently form (a) a cup-shaped bottom electrode component in the tub opening and (b) a bottom electrode contact in the bottom electrode contact opening, wherein each of the cup-shaped bottom electrode component and the bottom electrode contact is conductively coupled to the bottom electrode base.

[0108] At 1310, a fill metal (e.g., titanium nitride) is deposited to form a bottom electrode fill component in an interior opening defined by the cup-shaped bottom electrode component. At 1312, a planarization process is performed to define the final form of the cup-shaped bottom electrode component and bottom electrode fill component, and to define a planarized insulator support surface including a planarized top surface of the cup-shaped bottom electrode component, a planarized top surface of the bottom electrode fill component and planarized top surface areas of the dielectric region on opposite sides of the bottom electrode. The cup-shaped bottom electrode component and the bottom electrode fill component collectively define the capacitor bottom electrode.

[0109] At 1314, a planar insulator is formed on the planarized insulator support surface. The planar insulator extends across and beyond the full lateral width of the bottom electrode (in the x-direction, or in both the x-direction and y-direction) and may have a uniform vertical thickness across the full lateral width of the planar insulator (in the x-direction, or in both the x-direction and y-direction). At 1316, an upper metal layer M.sub.x+1 is formed, including (a) a top electrode over the insulator and (b) a bottom electrode connection element conductively connected to the bottom electrode contact. The upper metal layer M.sub.x+1 may comprise an interconnect metal layer, e.g., a first interconnect metal layer (metal-1 layer) or a higher interconnect metal layer (e.g., comprising aluminum).

[0110] FIG. 14 is a flowchart showing an example method 1400 of forming an example integrated circuit structure including an example MIM capacitor module and nearby interconnect structure, according to one example. At 1402, a lower metal layer M.sub.x is formed, including a bottom electrode base and a lower interconnect element. In one example, the lower metal layer M.sub.x comprise a lower interconnect metal layer (e.g., comprising aluminum). In another example, the lower metal layer M.sub.x comprises a silicided polysilicon layer. At 1404, a dielectric region (e.g., an oxide region) is deposited over the lower metal layer M.sub.x, and planarized, for example by a CMP process.

[0111] Next, as indicated by the dashed line box in FIG. 14, a damascene process may be performed at 1406-1412 to form a bottom electrode and a bottom electrode contact of the MIM capacitor module. First, at 1406, the dielectric region is patterned and etched to form (a) a tub opening and a bottom electrode contact opening over the bottom electrode base and (b) an interconnect via opening over the lower interconnect element.

[0112] At 1408, a conformal metal (e.g., tungsten) is deposited to concurrently form (a) a cup-shaped bottom electrode component in the tub opening, (b) a bottom electrode contact in the bottom electrode contact opening, and (c) an interconnect via in the interconnect via opening.

[0113] At 1410, a fill metal (e.g., titanium nitride) is deposited to form a bottom electrode fill component in an interior opening defined by the cup-shaped bottom electrode component. At 1412, a planarization process is performed to define the final form of the cup-shaped bottom electrode component and bottom electrode fill component, and to define a planarized insulator support surface including a planarized top surface of the cup-shaped bottom electrode component, a planarized top surface of the bottom electrode fill component and planarized top surface areas of the dielectric region on opposite sides of the bottom electrode. The cup-shaped bottom electrode component and the bottom electrode fill component collectively define the capacitor bottom electrode.

[0114] At 1414, a planar insulator is formed on the planarized insulator support surface. The planar insulator extends across and beyond the full lateral width of the bottom electrode (in the x-direction, or in both the x-direction and y-direction) and may have a uniform vertical thickness across the full lateral width of the planar insulator (in the x-direction, or in both the x-direction and y-direction). At 1416, an upper metal layer M.sub.x+1 is formed, including (a) a top electrode over the insulator, (b) a bottom electrode connection element conductively connected to the bottom electrode contact, and (c) an upper interconnect element conductively connected to the interconnect via. The upper metal layer M.sub.x+1 may comprise an interconnect metal layer, e.g., a first interconnect metal layer (metal-1 layer) or a higher interconnect metal layer (e.g., comprising aluminum).