US20230378255A1 - Semiconductor structure having air gaps and method for manufacturing the same - Google Patents
Semiconductor structure having air gaps and method for manufacturing the same Download PDFInfo
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- US20230378255A1 US20230378255A1 US18/364,291 US202318364291A US2023378255A1 US 20230378255 A1 US20230378255 A1 US 20230378255A1 US 202318364291 A US202318364291 A US 202318364291A US 2023378255 A1 US2023378255 A1 US 2023378255A1
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Classifications
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- H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
- H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
- H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
- H01L21/76801—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing
- H01L21/7682—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing the dielectric comprising air gaps
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- H—ELECTRICITY
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
- H01L29/06—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions
- H01L29/0603—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions
- H01L29/0642—Isolation within the component, i.e. internal isolation
- H01L29/0649—Dielectric regions, e.g. SiO2 regions, air gaps
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- H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
- H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
- H01L21/76801—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing
- H01L21/76829—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing characterised by the formation of thin functional dielectric layers, e.g. dielectric etch-stop, barrier, capping or liner layers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
- H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
- H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
- H01L21/76801—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing
- H01L21/76829—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing characterised by the formation of thin functional dielectric layers, e.g. dielectric etch-stop, barrier, capping or liner layers
- H01L21/76831—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing characterised by the formation of thin functional dielectric layers, e.g. dielectric etch-stop, barrier, capping or liner layers in via holes or trenches, e.g. non-conductive sidewall liners
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
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- H01L21/76841—Barrier, adhesion or liner layers
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- H01L21/76877—Filling of holes, grooves or trenches, e.g. vias, with conductive material
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- H01L21/82—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices to produce devices, e.g. integrated circuits, each consisting of a plurality of components
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- H01L21/76829—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing characterised by the formation of thin functional dielectric layers, e.g. dielectric etch-stop, barrier, capping or liner layers
- H01L21/76834—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing characterised by the formation of thin functional dielectric layers, e.g. dielectric etch-stop, barrier, capping or liner layers formation of thin insulating films on the sidewalls or on top of conductors
Definitions
- FIG. 1 is a flow diagram illustrating a method for manufacturing a semiconductor structure having air gaps in accordance with some embodiments.
- FIGS. 2 to 12 illustrate schematic views showing intermediate stages of the method for manufacturing a semiconductor structure having air gaps as depicted in FIG. 1 .
- FIG. 13 is a flow diagram illustrating a method for manufacturing a semiconductor structure having air gaps in accordance with some embodiments.
- FIGS. 14 to 25 illustrate schematic views showing intermediate stages of the method for manufacturing a semiconductor structure having air gaps as depicted in FIG. 13 .
- FIGS. 26 to 36 illustrate schematic views showing intermediate stages of a method for manufacturing a semiconductor structure having air gaps.
- first and second features are formed in direct contact
- additional features may be formed between the first and second features, such that the first and second features may not be in direct contact
- 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.
- spatially relative terms such as “on,” “above,” “over,” “downwardly” and the like, may be used herein for ease of description to describe one element or feature'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.
- FIG. 1 illustrates a single damascene method 100 for manufacturing a semiconductor structure having air gaps in accordance with some embodiments.
- FIGS. 2 to 12 illustrate schematic views of a semiconductor structure 200 during various stages of the single damascene method 100 of FIG. 1 .
- the single damascene method 100 and the semiconductor structure 200 are collectively described below. However, additional steps can be provided before, after or during the single damascene method 100 , and some of the steps described herein may be replaced by other steps or be eliminated. Similarly, further additional features may be present in the semiconductor structure 200 , and/or features present may be replaced or eliminated in additional embodiments.
- the single damascene method 100 begins at block 102 , where trenches are formed in a dielectric structure.
- a dielectric structure 30 formed with trenches 307 is prepared on an interconnect structure 20 disposed over a substrate 10 .
- the dielectric structure 30 may be prepared by sequentially depositing a first etch stop layer 301 , a first low-k dielectric layer 302 , and a dielectric capping layer 303 on the interconnect structure 20 , and patterning the dielectric capping layer 303 , the first low-k dielectric layer 302 , and the first etch stop layer 301 by one or more etching processes (for example, dry etching, wet etching, or a combination thereof) through a pattern opening of a patterned mask layer (not shown).
- etching processes for example, dry etching, wet etching, or a combination thereof
- the dielectric structure 30 thus prepared includes a patterned etch stop layer 304 disposed on the interconnect structure 20 , a patterned dummy layer 305 disposed on the patterned etch stop layer 304 , and a patterned dielectric capping layer 306 disposed on the patterned dummy layer 305 .
- the dielectric structure 30 is formed with a plurality of the trenches 307 extending through the patterned dielectric capping layer 306 , the patterned dummy layer 305 , and the patterned etch stop layer 304 .
- the trenches 307 are defined by lateral surfaces 308 of the dielectric structure 30 .
- Materials suitable for forming the first etch stop layer 301 include, for example, silicon, silicon oxide, silicon nitride, silicon carbide, silicon oxycarbide, silicon oxynitride, silicon carbonitride, silicon oxycarbonitride, cobalt, ruthenium, tungsten, titanium nitride, zirconium oxide, aluminum oxide, yttrium oxide, aluminum oxynitride, hafnium oxide, hafnium zirconium oxide, hafnium silicon oxide, hafnium silicon oxynitride, zirconium silicon oxide, hafnium zirconium silicon oxide, hafnium aluminum oxide, hafnium aluminum nitride, zirconium aluminum oxide, ytterbium oxide, tantalum nitride, tantalum silicon nitride, tantalum oxide, tantalum silicon oxide, titanium nitride, titanium silicon nitride, titanium oxide, titanium silicon oxide, and combinations thereof, but are not limited there
- the deposition of the first etch stop layer 301 on the interconnect structure 20 may be implemented by a suitable deposition process as is known to those skilled in the art of semiconductor fabrication, for example, physical vapor deposition (PVD), chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), plasma-enhanced atomic layer deposition (PEALD), etc., or combinations thereof, but not limited thereto.
- the first etch stop layer 301 may have a thickness ranging from 1 ⁇ acute over ( ⁇ ) ⁇ to 100 ⁇ acute over ( ⁇ ) ⁇ .
- Materials suitable for forming the first low-k dielectric layer 302 include silicon oxide, silicon oxycarbide, silicon oxynitride, silicon oxycarbonitride, and combinations thereof, but are not limited thereto, and have a k-value ranging from 1.0 to 3.9.
- the deposition of the first low-k dielectric layer 302 on the first etch stop layer 301 may be implemented by a suitable deposition process as is known to those skilled in the art of semiconductor fabrication, for example, PVD, CVD, PECVD, ALD, PEALD, etc., or combinations thereof, but not limited thereto.
- the first low-k dielectric layer 302 may have a thickness ranging from 10 ⁇ acute over ( ⁇ ) ⁇ to 5000 ⁇ acute over ( ⁇ ) ⁇ . When the first low-k dielectric layer 302 is made of silicon oxycarbide, an amount of carbon present in silicon oxycarbide is up to 50%.
- the first low-k dielectric layer 302 may be formed of a single layer or multiple
- Materials suitable for forming the dielectric capping layer 303 include, for example, silicon, silicon oxide, silicon nitride, silicon carbide, silicon oxycarbide, silicon oxynitride, silicon carbonitride, silicon oxycarbonitride, cobalt, ruthenium, tungsten, titanium nitride, zirconium oxide, aluminum oxide, yttrium oxide, aluminum oxynitride, hafnium oxide, hafnium zirconium oxide, hafnium silicon oxide, hafnium silicon oxynitride, zirconium silicon oxide, hafnium zirconium silicon oxide, hafnium aluminum oxide, hafnium aluminum nitride, zirconium aluminum oxide, ytterbium oxide, tantalum nitride, tantalum silicon nitride, tantalum oxide, tantalum silicon oxide, titanium nitride, titanium silicon nitride, titanium oxide, titanium silicon oxide, and combinations thereof, but are not limited there
- the deposition of the dielectric capping layer 303 on the first low-k dielectric layer 302 may be implemented by a suitable deposition process as is known to those skilled in the art of semiconductor fabrication, for example, PVD, CVD, PECVD, ALD, PEALD, etc., or combinations thereof, but not limited thereto.
- the dielectric capping layer 303 may have a thickness ranging from 1 ⁇ acute over ( ⁇ ) ⁇ to 500 ⁇ acute over ( ⁇ ) ⁇ .
- the substrate 10 may be a semiconductor substrate, e.g., an elemental semiconductor or a compound semiconductor.
- An elemental semiconductor is composed of single species of atoms, such as silicon (Si) or germanium (Ge) in column IV of the periodic table.
- a compound semiconductor is composed of two or more elements, such as silicon carbide (SiC), gallium arsenide (GaAs), gallium phosphide (GaP), indium phosphide (InP), indium arsenide (InAs), indium antimonide (InSb), silicon germanium (SiGe), gallium arsenide phosphide (GaAsP), aluminum indium arsenide (AlInAs), aluminum gallium arsenide (AlGaAs), gallium indium arsenide (GaInAs), gallium indium phosphide (GaInP), gallium indium arsenide phosphide (GaInAsP), or the like.
- the compound semiconductor may have a gradient feature in which the composition thereof changes from one ratio at one location to another ratio at another location in the compound semiconductor.
- the compound semiconductor may be formed over a silicon substrate.
- the compound semiconductor may be strained.
- the substrate 10 may include a multilayer compound semiconductor structure.
- the substrate 10 may include a non-semiconductor material, such as a glass, fused quartz, or calcium fluoride.
- the substrate 10 may be a semiconductor on insulator (SOI) (e.g., silicon germanium on insulator (SGOI)).
- SOI semiconductor on insulator
- SGOI silicon germanium on insulator
- an SOI substrate includes a layer of a semiconductor material such as epitaxial silicon (Si), germanium (Ge), silicon germanium (SiGe), and combinations thereof.
- the substrate may be doped with a p-type dopant, such as boron (Br), aluminum (Al), gallium (Ga), or the like, or may alternatively be doped with an n-type dopant, as is known in the art.
- the substrate 10 may include a doped epitaxial layer. Shallow trench isolation (STI) regions (not shown) may be formed in the substrate 10 to isolate active regions (one is schematically shown in FIG. 2 with the numeral 101 ), such as source or drain regions of an integrated circuit device (not shown) in the substrate 10 .
- STI Shallow trench isolation
- the integrated circuit device may include complementary metal-oxide semiconductor (CMOS) transistors, planar or vertical multi-gate transistors (e.g., FinFET devices), gate-all-around (GAA) devices, resistors, capacitors, diodes, transistors (e.g., field-effect transistors (FETs)), interconnections, or the like, based on practical applications.
- CMOS complementary metal-oxide semiconductor
- GAA gate-all-around
- resistors e.g., capacitors, diodes
- transistors e.g., field-effect transistors (FETs)
- interconnections e.g., interconnections, or the like, based on practical applications.
- through-vias may be formed to extend into the substrate 10 for electrically connecting features on opposite sides of the substrate 10 .
- the interconnect structure 20 includes a dielectric layer 203 and at least one interconnect 201 (for example, an electrically conductive via), which is formed in the dielectric layer 203 and which is electrically connected to the active region 101 of the substrate 10 .
- the dielectric layer 203 may be made of a dielectric material, such as silicon oxide, SiOC-based materials (e.g., SiOCH), borophosphosilicate glass (BPSG), undoped silicate glass (USG), fluorinated silicate glass (FSG), high-density plasma (HDP) oxide, fluorine-doped silicon oxide, carbon-doped silicon oxide, porous silicon oxide, porous carbon-doped silicon oxide, organic polymers, or silicone based polymers.
- SiOC-based materials e.g., SiOCH
- BPSG borophosphosilicate glass
- USG undoped silicate glass
- FSG fluorinated silicate glass
- HDP high-density plasma
- silicon oxide may be formed from tetraethyl orthosilicate (TEOS).
- TEOS tetraethyl orthosilicate
- the dielectric layer 203 may be formed on the substrate 10 by a suitable deposition process as is known to those skilled in the art of semiconductor fabrication, for example, ALD, CVD, PVD, or combinations thereof.
- a deposition layer is formed to cover the dielectric structure.
- a deposition layer 40 is conformally formed on and covers the dielectric structure 30 .
- the deposition of the deposition layer 40 on the dielectric structure 30 may be implemented by a suitable deposition process as is known to those skilled in the art of semiconductor fabrication, for example, PVD, CVD, PECVD, ALD, PEALD, etc., or combinations thereof, but not limited thereto.
- Materials suitable for forming the deposition layer 40 include, for example, silicon, silicon oxide, silicon nitride, silicon carbide, silicon oxycarbide, silicon oxynitride, silicon carbonitride, silicon oxycarbonitride, cobalt, ruthenium, tungsten, titanium nitride, zirconium oxide, aluminum oxide, yttrium oxide, aluminum oxynitride, hafnium oxide, hafnium zirconium oxide, hafnium silicon oxide, hafnium silicon oxynitride, zirconium silicon oxide, hafnium zirconium silicon oxide, hafnium aluminum oxide, hafnium aluminum nitride, zirconium aluminum oxide, ytterbium oxide, tantalum nitride, tantalum silicon nitride, tantalum oxide, tantalum silicon oxide, titanium nitride, titanium silicon nitride, titanium oxide, titanium silicon oxide, and combinations thereof, but are not limited thereto.
- the method 100 then proceeds to block 106 where a plurality of spacer layers are formed.
- the dielectric structure 30 formed with the deposition layer 40 as shown in FIG. 4 is subjected to anisotropic etching to etch away the patterned dielectric capping layer 306 and the horizontal portions of the deposition layer 40 so as to form the deposition layer 40 into a plurality of spacer layers 401 on the lateral surfaces 308 of the dielectric structure 30 exposed by the trenches 307 .
- the dielectric capping layer 306 may be partially remained after the anisotropic etching, and may be removed in a subsequent operation.
- the anisotropic etching may be implemented by a suitable anisotropic etching treatment as is known in the art of semiconductor fabrication, such as dry vertical anisotropic etching, but not limited thereto.
- first electrically conductive features are formed.
- a first electrically conductive material is filled into the trenches 307 to form a plurality of first electrically conductive features 309 , such as electrically conductive metal lines.
- the first electrically conductive material may be, for example, copper (Cu), aluminum (Al), gold (Au), silver (Ag), tungsten (W), cobalt (Co), ruthenium (Ru), tantalum (Ta), etc., or alloys thereof.
- the first electrically conductive material may be provided as multiple layers having varying composition, and may be filled into the trenches 307 by a suitable process as is known in the art of semiconductor fabrication, such as electroless plating, electroplating, sputter deposition, or CVD, but not limited thereto.
- Electroless plating of copper generally includes forming a seed layer followed by autocatalytic copper deposition.
- the material for the seed layer include Cu, nickel (Ni), Au, Ag, palladium (Pd), Iridium (Ir), nickel-palladium-gold (NiPdAu), and nickel-gold (NiAu), but not limited thereto.
- the seed layer can be formed by a suitable process as is known in the art of semiconductor fabrication, such as electroless deposition, sputtering, or CVD, but not limited thereto.
- the trenches 307 may be lined with a barrier layer 310 that prevents electromigration.
- a barrier layer 310 that prevents electromigration.
- materials for the barrier layer 310 include Ru, manganese (Mn), Co, chromium (Cr), titanium nitride (TiN), titanium tungsten (TiW), Ta, tantalum nitride (TaN), tungsten nitride (WN), and combinations thereof.
- the barrier layer 310 can be deposited by a suitable process, such as CVD or ALD.
- a planarization treatment for example, chemical mechanical planarization (CMP) is then implemented to remove excess of the first electrically conductive material, so as to permit top surfaces of the first electrically conductive features 309 and the patterned dummy layer 305 to be horizontally flush with each other. It should be noted that if the patterned dielectric capping layer 306 is not removed completely in forming the spacer layers 401 , it can be removed by the planarization treatment.
- CMP chemical mechanical planarization
- the method 100 then proceeds to block 110 where a conductive material is selectively deposited on the first electrically conductive features to form a conductive capping layer.
- a conductive material is selectively deposited on the first electrically conductive features to form a conductive capping layer.
- the first electrically conductive features 309 are then subjected to selective deposition of a conductive material to form a conductive capping layer 50 such that the first electrically conductive features 309 are covered by the conductive capping layer 50 and the spacer layers 401 .
- a self-assembled monolayer SAM
- SAM self-assembled monolayer
- the SAM material includes a head group which contains phosphorus (P), sulfur (S), nitrogen (N), or silicon (Si).
- the head group of SAM may include phosphate, sulfate, or silane based materials.
- SAM may include benzotriazole (BTA), phosphonic acid, octadecylphosphonic (ODPA), organosulfur compound, thiol (e.g., dodecanethiol, alkanethiol, or the like), or the like.
- SAM further includes a tail group which is connected to the head group and which contains an organic chain, such as CHx or the like.
- the conductive material may be selectively deposited on the first electrically conductive features 309 by a suitable method as is known to those skilled in the art of semiconductor fabrication, such as ALD, CVD, spin-on deposition, etc., or combinations thereof, to form the conductive capping layer 50 .
- the conductive capping layer 50 may be selectively deposited on the first electrically conductive features 309 directly by ALD, CVD, spin-on deposition, etc. using the controlled operation parameters without the selective formation of SAM in advance.
- the conductive capping layer 50 may be selectively deposited on the first electrically conductive features 309 by electroplating.
- the conductive capping layer 50 may be thermally annealed at a temperature ranging from 30° C. to 500° C. for a time period ranging from 1 second to 300 minutes.
- the electrically conductive features for example, metal lines
- the semiconductor structure 200 may be damaged.
- the conductive material suitable for forming the conductive capping layer 50 is a thermally or electrically conductive material, examples of which include conductive carbon-based materials (for example, amorphous carbon, graphene, graphite, etc.), conductive polymers (for example, poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT-PSS), polyaniline, etc), conductive organic composites, conductive ceramic composites, conductive metal composites (for example, metals and alloys), and combinations thereof, but are not limited thereto.
- the conductive capping layer 50 may have a thickness ranging from 1 ⁇ acute over ( ⁇ ) ⁇ to 100 ⁇ acute over ( ⁇ ) ⁇ .
- the method 100 then proceeds to block 112 where a plurality of recesses are formed among the first electrically conductive features.
- the patterned dummy layer 305 is etched away by a suitable etching method as is known to those skilled in the art of semiconductor fabrication, such as dry plasma etching, wet chemical etching, radical etching, gas etching, vapor etching, or combinations thereof, so as to form a plurality of recesses 402 among the first electrically conductive features 309 .
- the etching chamber tools suitable for implementing the etching method include a capacitively-coupled plasma (CCP) tool, an inductively-coupled plasma (ICP) tool, etc.
- the wet chemicals suitable for the wet chemical etching include fluorine-containing chemicals (for example, a hydrogen fluoride (HF) solution), amine-containing chemicals (for example, an amine (NH 3 ) solution), etc., but are not limited thereto.
- the dry plasma gas and gas phase reactants suitable for the etching method include a fluorine-based gas (for example, HF, CF 4 , C 4 F 8 , etc.), an amine-based gas (for example, NH 3 ), chlorine (Cl 2 ) gas, oxygen (O 2 ) gas, nitrogen (N 2 ) gas, argon (Ar) gas, and combinations thereof, but are not limited thereto.
- the depths of the recesses 402 can be tuned by, for example, controlling the operation parameters of the etching chamber tools, selecting proper wet chemicals, dry plasma gas, and gas phase reactants, etc.
- the wet chemicals, the dry plasma gas, and the gas phase reactants for the etching method have an etch selectivity of dielectric to metal ranging from 1 to 600.
- the depths of the recesses 402 range from 10 ⁇ acute over ( ⁇ ) ⁇ to 1000 ⁇ acute over ( ⁇ ) ⁇ .
- the etch landing of the recesses 402 ranges from 10 ⁇ acute over ( ⁇ ) ⁇ to 500 ⁇ acute over ( ⁇ ) ⁇ .
- etch stop layer is formed to cover the spacer layers, the conductive capping layer, and the patterned etch stop layer.
- a second etch stop layer 60 is formed in the recesses 402 and over the first electrically conductive features 309 , and is conformally deposited to cover the spacer layers 401 , the conductive capping layer 50 , and the patterned etch stop layer 304 .
- the second etch stop layer 60 is conformed in profile to a combined profile of the first electrically conductive features 309 , the spacer layers 401 , the conductive capping layer 50 , and the patterned etch stop layer 304 .
- Materials suitable for forming the second etch stop layer 60 include, for example, silicon, silicon oxide, silicon nitride, silicon carbide, silicon oxycarbide, silicon oxynitride, silicon carbonitride, silicon oxycarbonitride, cobalt, ruthenium, tungsten, titanium nitride, zirconium oxide, aluminum oxide, yttrium oxide, aluminum oxynitride, hafnium oxide, hafnium zirconium oxide, hafnium silicon oxide, hafnium silicon oxynitride, zirconium silicon oxide, hafnium zirconium silicon oxide, hafnium aluminum oxide, hafnium aluminum nitride, zirconium aluminum oxide, ytterbium oxide, tantalum nitride, tantalum silicon nitride, tantalum oxide, tantalum silicon oxide, titanium nitride, titanium silicon nitride, titanium oxide, titanium silicon oxide, and combinations thereof, but are not limited thereto
- the conformal deposition of the second etch stop layer 60 to cover the spacer layers 401 , the conductive capping layer 50 , and the patterned etch stop layer 304 may be implemented by a suitable deposition process as is known to those skilled in the art of semiconductor fabrication, for example, PVD, CVD, PECVD, ALD, PEALD, etc., or combinations thereof, but not limited thereto.
- the second etch stop layer 60 may have a thickness ranging from 1 A to 100 A.
- the second etch stop layer 60 includes a top portion 601 and a surrounding portion 602 .
- the top portion 601 is disposed over the first electrically conductive features 309 and covers the conductive capping layer 50 .
- the surrounding portion 602 extends downwardly from the top portion 601 to cover the spacer layers 401 and the patterned etch stop layer 304 .
- the method 100 then proceeds to block 116 where a dielectric layer having air gaps is formed.
- a dielectric material is deposited in the recesses 402 and over the first electrically conductive features 309 (specifically, on the second etch stop layer 60 ) to form a second low-k dielectric layer 70 which has air gaps 701 among the first electrically conductive features 309 .
- Examples of the dielectric material suitable for forming the second low-k dielectric layer 70 include silicon oxide, silicon oxycarbide, silicon oxynitride, silicon oxycarbonitride, and combinations thereof, but are not limited thereto, and have a k-value ranging from 1.0 to 3.9, a porosity ranging from 0.1% to 10%, and a hardness ranging from 1 to 10.
- the deposition of the second low-k dielectric layer 70 on the second etch stop layer 60 may be implemented by a suitable deposition process as is known to those skilled in the art of semiconductor fabrication, for example, PVD, CVD, PECVD, ALD, PEALD, spin-on deposition, etc., or combinations thereof, but not limited thereto.
- the second low-k dielectric layer 70 may have a thickness ranging from 100 ⁇ acute over ( ⁇ ) ⁇ to 2000 ⁇ acute over ( ⁇ ) ⁇ .
- an amount of carbon present in silicon oxycarbide is up to 50%.
- the method 100 then proceeds to block 118 where at least one hole is formed in the dielectric layer.
- the second low-k dielectric layer 70 , the second etch stop layer 60 , and the conductive capping layer 50 are patterned by one or more etching processes (for example, dry etching, wet etching, or a combination thereof) through a pattern opening of a patterned mask layer (not shown) to form at least one hole 702 in the second low-k dielectric layer 70 .
- the at least one hole 702 penetrates through the second low-k dielectric layer 70 , the top portion 601 of the second etch stop layer 60 , and the conductive capping layer 50 such that at least one of the first electrically conductive features 309 is exposed from the at least one hole 702 , respectively.
- the hole 702 penetrates through the top portion 601 of the second etch stop layer 60 and is positioned within the top portion 601 of the second etch stop layer 60 .
- the method 100 then proceeds to block 120 where at least one second electrically conductive feature is formed.
- a second electrically conductive material is filled into the at least one hole 702 to form at least one second electrically conductive feature 703 electrically connected to the at least one of the first electrically conductive features 309 , respectively.
- the at least one hole 702 penetrates through the top portion 601 of the second etch stop layer 60 and is positioned within the top portion 601 of the second etch stop layer 60 , such that the second electrically conductive feature 703 is formed to penetrate through the top portion 601 of the second etch stop layer 60 and to be positioned within the top portion 601 of the second etch stop layer 60 .
- the second electrically conductive material may be the same as or different from the first electrically conductive material, and may be, for example, Cu, Al, Au, Ag, W, Co, Ru, Ta, etc., or alloys thereof.
- the second electrically conductive material may be provided as multiple layers having varying composition, and may be filled into the at least one hole 702 by a suitable process as is known in the art of semiconductor fabrication, such as electroless plating, electroplating, sputter deposition, or CVD, but not limited thereto. Details regarding the formation of at least one second electrically conductive feature 703 are the same as or similar to those regarding the formation of the first electrically conductive features 309 described above with reference to FIGS. 5 and 6 . In addition, similarly to that described above with reference to FIGS. 5 and 6 , before filling copper or the like into the at least one hole 702 , the at least one hole 702 may be lined with a barrier layer 704 that prevents electromigration.
- the at least one second electrically conductive feature 703 thus formed penetrates through the second low-k dielectric layer 70 , the top portion 601 of the second etch stop layer 60 , and the conductive capping layer 50 , and is electrically connected to the at least one of the first electrically conductive features 309 , respectively. Specifically, the at least one second electrically conductive feature 703 penetrates through the top portion 601 of the second etch stop layer 60 and is positioned within the top portion 601 of the second etch stop layer 60 .
- FIG. 13 illustrates a dual damascene method 500 for manufacturing a semiconductor structure having air gaps in accordance with some embodiments.
- FIGS. 14 to 25 illustrate schematic views of a semiconductor structure 600 during various stages of the dual damascene method 500 of FIG. 13 .
- the dual damascene method 500 and the semiconductor structure 600 are collectively described below. However, additional steps can be provided before, after or during the single damascene method 500 , and some of the steps described herein may be replaced by other steps or be eliminated. Similarly, further additional features may be present in the semiconductor structure 600 , and/or features present may be replaced or eliminated in additional embodiments.
- the dual damascene method 500 begins at block 502 , where a plurality of trenches and at least one via opening are formed in a dielectric structure.
- a dielectric structure 30 formed with a plurality of trenches 307 and at least one via opening 307 ′ is prepared on a metal layer 20 ′.
- the metal layer 20 ′ is formed on an interconnect structure 20 disposed over a substrate 10 , and includes a dielectric layer 203 ′ and at least one metal line 202 ′ formed in the dielectric layer 203 ′.
- a barrier layer 201 ′ may be formed to prevent electromigration.
- the dielectric structure 30 may be prepared by sequentially depositing a first etch stop layer 301 , a dielectric base layer 302 ′, a first low-k dielectric layer 302 , and a dielectric capping layer 303 on the metal layer 20 ′, and patterning the dielectric capping layer 303 , the first low-k dielectric layer 302 , the dielectric base layer 302 ′, and the first etch stop layer 301 by one or more etching processes (for example, dry etching, wet etching, or a combination thereof) through a pattern opening of a patterned mask layer (not shown).
- etching processes for example, dry etching, wet etching, or a combination thereof
- the first etch stop layer 301 may includes a lower etch stop sub-layer 3011 deposited on the metal layer 20 ′ and an upper etch stop sub-layer 3012 deposited on the lower etch stop sub-layer 3011 .
- the dielectric structure 30 thus prepared includes a patterned etch stop layer 304 disposed on the metal layer 20 ′, a patterned dielectric base layer 305 ′ disposed on the patterned etch stop layer 304 , a patterned dummy layer 305 disposed on the patterned dielectric base layer 305 ′, and a patterned dielectric capping layer 306 disposed on the patterned dummy layer 305 .
- the patterned etch stop layer 304 may includes a lower patterned etch stop sub-layer 3041 disposed on the metal layer 20 ′ and an upper patterned etch stop sub-layer 3042 disposed on the lower patterned etch stop sub-layer 3041 .
- the dielectric structure 30 is thus formed with the plurality of the trenches 307 and the at least one via opening 307 ′, which are defined by lateral surfaces 308 of the dielectric structure 30 .
- the trenches 307 extend through the patterned dielectric capping layer 306 and the patterned dummy layer 305 .
- the at least one via opening 307 ′ extends through the patterned dielectric base layer 305 ′ and the patterned etch stop layer 304 , and is disposed below and spatially communicated with at least one of the trenches 307 , respectively.
- Materials suitable for forming the lower etch stop sub-layer 3011 and the upper etch stop sub-layer 3012 independently include, for example, silicon, silicon oxide, silicon nitride, silicon carbide, silicon oxycarbide, silicon oxynitride, silicon carbonitride, silicon oxycarbonitride, cobalt, ruthenium, tungsten, titanium nitride, zirconium oxide, aluminum oxide, yttrium oxide, aluminum oxynitride, hafnium oxide, hafnium zirconium oxide, hafnium silicon oxide, hafnium silicon oxynitride, zirconium silicon oxide, hafnium zirconium silicon oxide, hafnium aluminum oxide, hafnium aluminum nitride, zirconium aluminum oxide, ytterbium oxide, tantalum nitride, tantalum silicon nitride, tantalum oxide, tantalum silicon oxide, titanium nitride, titanium silicon nitride, titanium oxide
- the deposition of the lower etch stop sub-layer 3011 and the upper etch stop sub-layer 3012 on the metal layer 20 ′ may be implemented by a suitable deposition process as is known to those skilled in the art of semiconductor fabrication, for example, PVD, CVD, PECVD, ALD, PEALD, etc., or combinations thereof, but not limited thereto.
- the first etch stop layer 301 i.e., a combination of the lower etch stop sub-layer 3011 and the upper etch stop sub-layer 3012
- Materials suitable for forming the dielectric base layer 302 ′ include silicon oxide, silicon oxycarbide, silicon oxynitride, silicon oxycarbonitride, and combinations thereof, but are not limited thereto, and have a k-value ranging from 1.0 to 3.9.
- the deposition of the dielectric base layer 302 ′ on the first etch stop layer 301 may be implemented by a suitable deposition process as is known to those skilled in the art of semiconductor fabrication, for example, PVD, CVD, PECVD, ALD, PEALD, etc., or combinations thereof, but not limited thereto.
- the dielectric base layer 302 ′ may have a thickness ranging from 10 ⁇ acute over ( ⁇ ) ⁇ to 5000 ⁇ acute over ( ⁇ ) ⁇ .
- first low-k dielectric layer 302 Details regarding the formation of the first low-k dielectric layer 302 are the same as or similar to those regarding the formation of the first low-k dielectric layer 302 described above with reference to FIG. 2 .
- dielectric capping layer 303 Details regarding the formation of the dielectric capping layer 303 are the same as or similar to those regarding the formation of the dielectric capping layer 303 described above with reference to FIG. 2 .
- a deposition layer is conformally formed to cover the dielectric structure.
- a deposition layer 40 is conformally formed on and covers the dielectric structure 30 . Details regarding the formation of the deposition layer 40 are the same as or similar to those regarding the formation of the deposition layer 40 described above with reference to FIG. 4 .
- the method 500 then proceeds to block 506 where a plurality of spacer layers are formed.
- the dielectric structure 30 formed with the deposition layer 40 as shown in FIG. 16 is subjected to anisotropic etching to etch away the horizontal portions of the deposition layer 40 so as to form the deposition layer 40 into a plurality of spacer layers 401 on the lateral surfaces 308 of the dielectric structure 30 .
- Details regarding the formation of the spacer layers 401 are the same as or similar to those regarding the formation of the spacer layers 401 described above with reference to FIGS. 4 and 5 .
- At least one of the spacer layers 401 includes a lower spacer sub-layer 4011 and an upper spacer sub-layer 4012 separated from the lower spacer sub-layer 4011 by an intermediate surface 3051 ′ of the patterned dielectric base layer 305 ′.
- the lower spacer sub-layer 4011 is formed on a lower portion 3081 of a corresponding one of the lateral surfaces 308 exposed by the at least one via opening 307 ′
- the upper spacer sub-layer 4012 is formed on an upper portion 3082 of the corresponding one of the lateral surfaces 308 exposed by a corresponding one of the trenches 307 .
- the patterned dielectric capping layer 306 may be moved away together with the horizontal portions of the deposition layer 40 by the anisotropic etching.
- the method 500 then proceeds to block 508 where first electrically conductive features are formed.
- first electrically conductive features are formed. Referring to the example illustrated in FIGS. 17 and 18 , a first electrically conductive material is filled into the plurality of the trenches 307 and the at least one via opening 307 ′ to form a plurality of first electrically conductive features 309 .
- At least one of the first electrically conductive features 309 includes a lower electrically conductive sub-feature 3091 (i.e., an electrically conductive via) disposed in the dielectric patterned base layer 305 ′ and electrically connected to the at least one metal line 202 ′ of the metal layer 20 ′, and an upper electrically conductive sub-feature 3092 (i.e., a metal line) disposed in the patterned dummy layer 305 and connected to the lower electrically conductive sub-feature 3091 .
- a lower electrically conductive sub-feature 3091 i.e., an electrically conductive via
- an upper electrically conductive sub-feature 3092 i.e., a metal line
- first electrically conductive features 309 are the same as or similar to those regarding the formation of the first electrically conductive features 309 described above with reference to FIGS. 5 and 6 .
- the plurality of the trenches 307 and the at least one via opening 307 ′ may be lined with a barrier layer 310 that prevents electromigration.
- the intermediate surface 3051 ′ of the patterned dielectric base layer 305 ′ is in contact with a portion of the barrier layer 301 below the upper electrically conductive sub-feature 3092 .
- a planarization treatment (for example, CMP) is then implemented to remove excess of the first electrically conductive material, portions of the spacer layers 401 , and the patterned dielectric capping layer 306 until top surfaces of the first electrically conductive features 309 and the patterned dummy layer 305 to be horizontally flush with each other.
- CMP planarization treatment
- the method 500 then proceeds to block 510 where a conductive material is selectively deposited on the first electrically conductive features to form a conductive capping layer.
- a conductive material is selectively deposited on the first electrically conductive features to form a conductive capping layer.
- the first electrically conductive features 309 are then subjected to selective deposition of a conductive material to form a conductive capping layer 50 such that the first electrically conductive features 309 are covered by the conductive capping layer 50 and the spacer layers 401 .
- Details regarding the formation of the conductive capping layer 50 are the same as or similar to those regarding the formation of the conductive capping layer 50 described above with reference to FIG. 7 .
- the method 500 then proceeds to block 512 where a plurality of recesses are formed among the first electrically conductive features.
- the patterned dummy layer 305 is etched away so as to form a plurality of recesses 402 among the first electrically conductive features 309 . Details regarding the formation of the recesses 402 are the same as or similar to those regarding the formation of the recesses 402 described above with reference to FIGS. 7 and 8 .
- etch stop layer is conformally formed to cover the spacer layers and the conductive capping layer.
- a second etch stop layer 60 is formed in the recesses 402 and over the first electrically conductive features 309 , and is conformally deposited to cover the patterned dielectric base layer 305 ′, the spacer layers 401 , and the conductive capping layer 50 .
- the second etch stop layer 60 is conformed in profile to a combined profile of the first electrically conductive features 309 , the spacer layers 401 , and the conductive capping layer 50 .
- the second etch stop layer 60 includes a top portion 601 covering the conductive capping layer 50 , and a surrounding portion 602 extending downwardly from the top portion 601 to cover the upper spacer sub-layer 4012 of the at least one of the spacer layers 401 and remaining ones of the spacer layers 401 .
- the method 500 then proceeds to block 516 where a dielectric layer having air gaps is formed.
- a dielectric material is deposited in the recesses 402 and over the first electrically conductive features 309 (specifically, on the second etch stop layer 60 ) to form a second low-k dielectric layer 70 which has air gaps 701 among the first electrically conductive features 309 .
- Details regarding the formation of the second low-k dielectric layer 70 having the air gaps 701 are the same as or similar to those regarding the formation of the second low-k dielectric layer 70 having the air gaps 701 described above with reference to FIG. 10 .
- the method 500 then proceeds to block 518 where at least one hole is formed in the dielectric layer.
- the second low-k dielectric layer 70 , the top portion 601 of the second etch stop layer 60 , and the conductive capping layer 50 are patterned by one or more etching processes (for example, dry etching, wet etching, or a combination thereof) through a pattern opening of a patterned mask layer (not shown) to form at least one hole 702 in the second low-k dielectric layer 70 .
- the at least one hole 702 penetrates through the second low-k dielectric layer 70 , the top portion 601 of the second etch stop layer 60 , and the conductive capping layer 50 , such that at least one of the first electrically conductive features 309 is exposed from the at least one hole 702 , respectively.
- the hole 702 penetrates through the top portion 601 of the second etch stop layer 60 and is positioned within the top portion 601 of the second etch stop layer 60 .
- the method 500 then proceeds to block 520 where at least one second electrically conductive feature is formed.
- a second electrically conductive material is filled into the at least one hole 702 to form at least one second electrically conductive feature 703 electrically connected to the at least one of the first electrically conductive features 309 , respectively.
- the at least one hole 702 penetrates through the top portion 601 of the second etch stop layer 60 and is positioned within the top portion 601 of the second etch stop layer 60 , such that the second electrically conductive feature 703 is formed to penetrate through the top portion 601 of the second etch stop layer 60 and to be positioned within the top portion 601 of the second etch stop layer 60 .
- the second electrically conductive material may be the same as or different from the first electrically conductive material, and may be, for example, Cu, Al, Au, Ag, W, Co, Ru, Ta, etc., or alloys thereof.
- the second electrically conductive material may be provided as multiple layers having varying composition, and may be filled into the at least one hole 702 by a suitable process as is known in the art of semiconductor fabrication, such as electroless plating, electroplating, sputter deposition, or CVD, but not limited thereto. Details regarding the formation of at least one second electrically conductive feature 703 are the same as or similar to those regarding the formation of the first electrically conductive features 309 described above with reference to FIGS. 5 and 6 . In addition, similarly to that described above with reference to FIGS. 5 and 6 , before filling copper or the like into the at least one hole 702 , the at least one hole 702 may be lined with a barrier layer 704 that prevents electromigration.
- the at least one second electrically conductive feature 703 thus formed penetrates through the second low-k dielectric layer 70 , the top portion of the second etch stop layer 60 , and the conductive capping layer 50 , and is electrically connected to the at least one of the first electrically conductive features 309 , respectively. Specifically, the at least one second electrically conductive feature 703 penetrates through the top portion 601 of the second etch stop layer 60 and is positioned within the top portion 601 of the second etch stop layer 60 .
- a method for manufacturing a semiconductor structure having air gaps includes the steps of: sequentially depositing a first etch stop layer 2 , a first low-k dielectric layer 3 , and a first dielectric capping layer 4 on an interconnect layer 1 , which is disposed over a substrate (not shown) and which is formed with an interconnect 11 (for example, an electrically conductive via); forming a plurality of first openings 31 in the first low-k dielectric layer 3 through one or more etching processes; filling a first electrically conductive material into the first openings 31 to form a plurality of first electrically conductive features 32 , one of which is electrically connected to the interconnect 11 ; implementing a planarization treatment (for example, CMP) to remove excess of the first electrically conductive material and the first dielectric capping layer 4 until the first low-k dielectric layer 3 is exposed; removing the first low-k dielectric layer 3 through an etching process; conformally depositing a second dielectric
- the air gaps 701 are formed among the first electrically conductive features 309 , and the conductive capping layer 50 is selectively deposited on the first electrically conductive features 309 , so the semiconductor structure 200 , 600 thus manufactured can provide both a relatively low capacitance and a relatively low resistance. Therefore, the RC performance of the semiconductor structure 200 , 600 can be improved significantly.
- the first electrically conductive features 309 are covered by the conductive capping layer 50 and the spacer layers 401 prior to formation of the recesses 402 . Therefore, the first electrically conductive features 309 are not damaged during the etching away of the patterned dummy layer 305 to form the recesses 402 .
- the conductive capping layer 50 is selectively deposited on the first electrically conductive features 309 prior to formation of the second low-k dielectric layer 70 and the second etch stop layer 60 , the at least one hole 702 for forming the at least one second electrically conductive feature 703 can be formed directly in the second low-k dielectric layer 70 by patterning without the planarization treatment such as CPM, and the cost for forming the at least one second electrically conductive feature 703 can thereby be reduced.
- the second etch stop layer 60 is conformally deposited to include the top portion 601 that covers the conductive capping layer 50 and the surrounding portion 602 that extends downwardly from the top portion 601 to cover the spacer layers 401 .
- the at least one hole 702 can be formed within the top portion 601 of the second etch stop layer 60 during patterning for forming the at least one hole 702 , such that the at least one second electrically conductive feature 703 can be formed within the top portion 601 of the second etch stop layer 60 . Therefore, the metal leakage issue can be prevented.
- a method for manufacturing a semiconductor structure includes forming a trench in a dielectric structure; forming a spacer layer on a lateral surface of the dielectric structure exposed by the trench; after forming the spacer layer, forming a first electrically conductive feature in the trench; removing at least portion of the dielectric structure to form a recess; forming an etch stop layer in the recess and over the first electrically conductive feature; and after forming the etch stop layer, depositing a dielectric layer in the recess and over the first electrically conductive feature.
- a semiconductor structure includes a first interconnect structure and a second interconnect structure.
- the first interconnect structure includes at least one electrically conductive element.
- the second interconnect structure is disposed on the first interconnect structure, and includes a plurality of first electrically conductive features, a plurality of spacer layers, an etch stop layer, and a dielectric layer.
- the first electrically conductive features are spaced apart from each other, and at least one of first electrically conductive features is electrically connected to the at least one electrically conductive element, respectively.
- the spacer layers laterally cover the first electrically conductive features.
- the etch stop layer conformally covers the spacer layers and is disposed over the first electrically conductive features.
- the dielectric layer is disposed on the etch stop layer.
- a semiconductor structure includes a first interconnect structure including an electrically conductive element; an electrically conductive feature electrically connected to the electrically conductive element; a spacer layer laterally covering the electrically conductive feature; a conductive capping layer disposed on the electrically conductive feature; an etch stop layer conformally covering the spacer layer and the conductive capping layer; and a dielectric layer surrounding the electrically conductive feature, the spacer layer, and the etch stop layer, and including an air gap adjacent to the electrically conductive feature.
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Abstract
A method for manufacturing a semiconductor structure includes forming a trench in a dielectric structure; forming a spacer layer on a lateral surface of the dielectric structure exposed by the trench; after forming the spacer layer, forming a first electrically conductive feature in the trench; removing at least portion of the dielectric structure to form a recess; forming an etch stop layer in the recess and over the first electrically conductive feature; and after forming the etch stop layer, depositing a dielectric layer in the recess and over the first electrically conductive feature.
Description
- This application is a divisional application of U.S. patent application Ser. No. 17/460,812, filed on Aug. 30, 2021, the content of which is incorporated herein by reference in its entirety.
- The integration density of various electronic components, such as transistors, diodes, resistors, capacitors, etc., is being improved continuously in the semiconductor industry by continual reduction in minimum feature sizes. As the feature sizes are decreased, the distance between metal features is continually reduced. As the distance between the metal features reduces, the resulting parasitic capacitance between the metal features increases, leading to higher power consumption and larger resistance-capacitance (RC) time delays for an integrated chip. To improve performance and reduce the parasitic capacitance between the metal features, materials having low dielectric (k) values are used. However, such dielectric materials encounter a lot of processing problems that prevent further improvement of the dielectric constant.
- The use of air gaps in semiconductor devices to enhance the isolation of the metal features is known in the art of semiconductor fabrication. Since air has a lowest k value (k=1), a growing trend has been to incorporate air gaps into the semiconductor devices to isolate the metal features and reduce line-to-line capacitance and the RC time delay.
- 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.
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FIG. 1 is a flow diagram illustrating a method for manufacturing a semiconductor structure having air gaps in accordance with some embodiments. -
FIGS. 2 to 12 illustrate schematic views showing intermediate stages of the method for manufacturing a semiconductor structure having air gaps as depicted inFIG. 1 . -
FIG. 13 is a flow diagram illustrating a method for manufacturing a semiconductor structure having air gaps in accordance with some embodiments. -
FIGS. 14 to 25 illustrate schematic views showing intermediate stages of the method for manufacturing a semiconductor structure having air gaps as depicted inFIG. 13 . -
FIGS. 26 to 36 illustrate schematic views showing intermediate stages of a method for manufacturing a semiconductor structure having air gaps. - The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. 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 “on,” “above,” “over,” “downwardly” and the like, may be used herein for ease of description to describe one element or feature'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.
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FIG. 1 illustrates a singledamascene method 100 for manufacturing a semiconductor structure having air gaps in accordance with some embodiments.FIGS. 2 to 12 illustrate schematic views of asemiconductor structure 200 during various stages of the singledamascene method 100 ofFIG. 1 . The singledamascene method 100 and thesemiconductor structure 200 are collectively described below. However, additional steps can be provided before, after or during thesingle damascene method 100, and some of the steps described herein may be replaced by other steps or be eliminated. Similarly, further additional features may be present in thesemiconductor structure 200, and/or features present may be replaced or eliminated in additional embodiments. - Referring to
FIG. 1 , the singledamascene method 100 begins atblock 102, where trenches are formed in a dielectric structure. Referring to the example illustrated inFIGS. 2 and 3 , adielectric structure 30 formed withtrenches 307 is prepared on aninterconnect structure 20 disposed over asubstrate 10. Thedielectric structure 30 may be prepared by sequentially depositing a firstetch stop layer 301, a first low-kdielectric layer 302, and adielectric capping layer 303 on theinterconnect structure 20, and patterning thedielectric capping layer 303, the first low-kdielectric layer 302, and the firstetch stop layer 301 by one or more etching processes (for example, dry etching, wet etching, or a combination thereof) through a pattern opening of a patterned mask layer (not shown). Thedielectric structure 30 thus prepared includes a patternedetch stop layer 304 disposed on theinterconnect structure 20, a patterneddummy layer 305 disposed on the patternedetch stop layer 304, and a patterneddielectric capping layer 306 disposed on the patterneddummy layer 305. Thedielectric structure 30 is formed with a plurality of thetrenches 307 extending through the patterneddielectric capping layer 306, thepatterned dummy layer 305, and the patternedetch stop layer 304. Thetrenches 307 are defined bylateral surfaces 308 of thedielectric structure 30. - Materials suitable for forming the first
etch stop layer 301 include, for example, silicon, silicon oxide, silicon nitride, silicon carbide, silicon oxycarbide, silicon oxynitride, silicon carbonitride, silicon oxycarbonitride, cobalt, ruthenium, tungsten, titanium nitride, zirconium oxide, aluminum oxide, yttrium oxide, aluminum oxynitride, hafnium oxide, hafnium zirconium oxide, hafnium silicon oxide, hafnium silicon oxynitride, zirconium silicon oxide, hafnium zirconium silicon oxide, hafnium aluminum oxide, hafnium aluminum nitride, zirconium aluminum oxide, ytterbium oxide, tantalum nitride, tantalum silicon nitride, tantalum oxide, tantalum silicon oxide, titanium nitride, titanium silicon nitride, titanium oxide, titanium silicon oxide, and combinations thereof, but are not limited thereto. The deposition of the firstetch stop layer 301 on theinterconnect structure 20 may be implemented by a suitable deposition process as is known to those skilled in the art of semiconductor fabrication, for example, physical vapor deposition (PVD), chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), plasma-enhanced atomic layer deposition (PEALD), etc., or combinations thereof, but not limited thereto. The firstetch stop layer 301 may have a thickness ranging from 1 {acute over (Å)} to 100 {acute over (Å)}. - Materials suitable for forming the first low-k
dielectric layer 302 include silicon oxide, silicon oxycarbide, silicon oxynitride, silicon oxycarbonitride, and combinations thereof, but are not limited thereto, and have a k-value ranging from 1.0 to 3.9. The deposition of the first low-kdielectric layer 302 on the firstetch stop layer 301 may be implemented by a suitable deposition process as is known to those skilled in the art of semiconductor fabrication, for example, PVD, CVD, PECVD, ALD, PEALD, etc., or combinations thereof, but not limited thereto. The first low-kdielectric layer 302 may have a thickness ranging from 10 {acute over (Å)} to 5000 {acute over (Å)}. When the first low-kdielectric layer 302 is made of silicon oxycarbide, an amount of carbon present in silicon oxycarbide is up to 50%. The first low-kdielectric layer 302 may be formed of a single layer or multiple layers of the material. - Materials suitable for forming the
dielectric capping layer 303 include, for example, silicon, silicon oxide, silicon nitride, silicon carbide, silicon oxycarbide, silicon oxynitride, silicon carbonitride, silicon oxycarbonitride, cobalt, ruthenium, tungsten, titanium nitride, zirconium oxide, aluminum oxide, yttrium oxide, aluminum oxynitride, hafnium oxide, hafnium zirconium oxide, hafnium silicon oxide, hafnium silicon oxynitride, zirconium silicon oxide, hafnium zirconium silicon oxide, hafnium aluminum oxide, hafnium aluminum nitride, zirconium aluminum oxide, ytterbium oxide, tantalum nitride, tantalum silicon nitride, tantalum oxide, tantalum silicon oxide, titanium nitride, titanium silicon nitride, titanium oxide, titanium silicon oxide, and combinations thereof, but are not limited thereto. The deposition of thedielectric capping layer 303 on the first low-kdielectric layer 302 may be implemented by a suitable deposition process as is known to those skilled in the art of semiconductor fabrication, for example, PVD, CVD, PECVD, ALD, PEALD, etc., or combinations thereof, but not limited thereto. Thedielectric capping layer 303 may have a thickness ranging from 1 {acute over (Å)} to 500 {acute over (Å)}. - In some embodiments, the
substrate 10 may be a semiconductor substrate, e.g., an elemental semiconductor or a compound semiconductor. An elemental semiconductor is composed of single species of atoms, such as silicon (Si) or germanium (Ge) in column IV of the periodic table. A compound semiconductor is composed of two or more elements, such as silicon carbide (SiC), gallium arsenide (GaAs), gallium phosphide (GaP), indium phosphide (InP), indium arsenide (InAs), indium antimonide (InSb), silicon germanium (SiGe), gallium arsenide phosphide (GaAsP), aluminum indium arsenide (AlInAs), aluminum gallium arsenide (AlGaAs), gallium indium arsenide (GaInAs), gallium indium phosphide (GaInP), gallium indium arsenide phosphide (GaInAsP), or the like. The compound semiconductor may have a gradient feature in which the composition thereof changes from one ratio at one location to another ratio at another location in the compound semiconductor. The compound semiconductor may be formed over a silicon substrate. The compound semiconductor may be strained. In some embodiments, thesubstrate 10 may include a multilayer compound semiconductor structure. Alternatively, thesubstrate 10 may include a non-semiconductor material, such as a glass, fused quartz, or calcium fluoride. Furthermore, in some embodiments, thesubstrate 10 may be a semiconductor on insulator (SOI) (e.g., silicon germanium on insulator (SGOI)). Generally, an SOI substrate includes a layer of a semiconductor material such as epitaxial silicon (Si), germanium (Ge), silicon germanium (SiGe), and combinations thereof. The substrate may be doped with a p-type dopant, such as boron (Br), aluminum (Al), gallium (Ga), or the like, or may alternatively be doped with an n-type dopant, as is known in the art. In some embodiments, thesubstrate 10 may include a doped epitaxial layer. Shallow trench isolation (STI) regions (not shown) may be formed in thesubstrate 10 to isolate active regions (one is schematically shown inFIG. 2 with the numeral 101), such as source or drain regions of an integrated circuit device (not shown) in thesubstrate 10. In some embodiments, the integrated circuit device may include complementary metal-oxide semiconductor (CMOS) transistors, planar or vertical multi-gate transistors (e.g., FinFET devices), gate-all-around (GAA) devices, resistors, capacitors, diodes, transistors (e.g., field-effect transistors (FETs)), interconnections, or the like, based on practical applications. In addition, through-vias (not shown) may be formed to extend into thesubstrate 10 for electrically connecting features on opposite sides of thesubstrate 10. - The
interconnect structure 20 includes adielectric layer 203 and at least one interconnect 201 (for example, an electrically conductive via), which is formed in thedielectric layer 203 and which is electrically connected to theactive region 101 of thesubstrate 10. Thedielectric layer 203 may be made of a dielectric material, such as silicon oxide, SiOC-based materials (e.g., SiOCH), borophosphosilicate glass (BPSG), undoped silicate glass (USG), fluorinated silicate glass (FSG), high-density plasma (HDP) oxide, fluorine-doped silicon oxide, carbon-doped silicon oxide, porous silicon oxide, porous carbon-doped silicon oxide, organic polymers, or silicone based polymers. In some embodiments, silicon oxide may be formed from tetraethyl orthosilicate (TEOS). Thedielectric layer 203 may be formed on thesubstrate 10 by a suitable deposition process as is known to those skilled in the art of semiconductor fabrication, for example, ALD, CVD, PVD, or combinations thereof. - The
method 100 then proceeds to block 104 wherein a deposition layer is formed to cover the dielectric structure. Referring to the example illustrated inFIG. 4 , adeposition layer 40 is conformally formed on and covers thedielectric structure 30. The deposition of thedeposition layer 40 on thedielectric structure 30 may be implemented by a suitable deposition process as is known to those skilled in the art of semiconductor fabrication, for example, PVD, CVD, PECVD, ALD, PEALD, etc., or combinations thereof, but not limited thereto. Materials suitable for forming thedeposition layer 40 include, for example, silicon, silicon oxide, silicon nitride, silicon carbide, silicon oxycarbide, silicon oxynitride, silicon carbonitride, silicon oxycarbonitride, cobalt, ruthenium, tungsten, titanium nitride, zirconium oxide, aluminum oxide, yttrium oxide, aluminum oxynitride, hafnium oxide, hafnium zirconium oxide, hafnium silicon oxide, hafnium silicon oxynitride, zirconium silicon oxide, hafnium zirconium silicon oxide, hafnium aluminum oxide, hafnium aluminum nitride, zirconium aluminum oxide, ytterbium oxide, tantalum nitride, tantalum silicon nitride, tantalum oxide, tantalum silicon oxide, titanium nitride, titanium silicon nitride, titanium oxide, titanium silicon oxide, and combinations thereof, but are not limited thereto. Thedeposition 40 may have a thickness ranging from 1 {acute over (Å)} to 200 {acute over (Å)}. - The
method 100 then proceeds to block 106 where a plurality of spacer layers are formed. Referring to the example illustrated inFIG. 5 , thedielectric structure 30 formed with thedeposition layer 40 as shown inFIG. 4 is subjected to anisotropic etching to etch away the patterneddielectric capping layer 306 and the horizontal portions of thedeposition layer 40 so as to form thedeposition layer 40 into a plurality of spacer layers 401 on the lateral surfaces 308 of thedielectric structure 30 exposed by thetrenches 307. In some embodiments, thedielectric capping layer 306 may be partially remained after the anisotropic etching, and may be removed in a subsequent operation. The anisotropic etching may be implemented by a suitable anisotropic etching treatment as is known in the art of semiconductor fabrication, such as dry vertical anisotropic etching, but not limited thereto. - The
method 100 then proceeds to block 108 where first electrically conductive features are formed. Referring to the example illustrated inFIGS. 5 and 6 , a first electrically conductive material is filled into thetrenches 307 to form a plurality of first electricallyconductive features 309, such as electrically conductive metal lines. - The first electrically conductive material may be, for example, copper (Cu), aluminum (Al), gold (Au), silver (Ag), tungsten (W), cobalt (Co), ruthenium (Ru), tantalum (Ta), etc., or alloys thereof. The first electrically conductive material may be provided as multiple layers having varying composition, and may be filled into the
trenches 307 by a suitable process as is known in the art of semiconductor fabrication, such as electroless plating, electroplating, sputter deposition, or CVD, but not limited thereto. - While the first electrically conductive material may be a suitable metal or alloy thereof as described above, the method of the present disclosure are particularly adapted to the use of Cu. Electroless plating of copper generally includes forming a seed layer followed by autocatalytic copper deposition. Examples of the material for the seed layer include Cu, nickel (Ni), Au, Ag, palladium (Pd), Iridium (Ir), nickel-palladium-gold (NiPdAu), and nickel-gold (NiAu), but not limited thereto. The seed layer can be formed by a suitable process as is known in the art of semiconductor fabrication, such as electroless deposition, sputtering, or CVD, but not limited thereto. Before filling copper or the like into the
trenches 307, thetrenches 307 may be lined with abarrier layer 310 that prevents electromigration. Examples of materials for thebarrier layer 310 include Ru, manganese (Mn), Co, chromium (Cr), titanium nitride (TiN), titanium tungsten (TiW), Ta, tantalum nitride (TaN), tungsten nitride (WN), and combinations thereof. Thebarrier layer 310 can be deposited by a suitable process, such as CVD or ALD. - A planarization treatment (for example, chemical mechanical planarization (CMP)) is then implemented to remove excess of the first electrically conductive material, so as to permit top surfaces of the first electrically
conductive features 309 and the patterneddummy layer 305 to be horizontally flush with each other. It should be noted that if the patterneddielectric capping layer 306 is not removed completely in forming the spacer layers 401, it can be removed by the planarization treatment. - The
method 100 then proceeds to block 110 where a conductive material is selectively deposited on the first electrically conductive features to form a conductive capping layer. Referring to the example illustrated inFIG. 7 , the first electricallyconductive features 309 are then subjected to selective deposition of a conductive material to form aconductive capping layer 50 such that the first electricallyconductive features 309 are covered by theconductive capping layer 50 and the spacer layers 401. For example, a self-assembled monolayer (SAM) may be selectively formed on the patterneddummy layer 305 to reduce the deposition rate of the conductive material on the patterneddummy layer 305 to be lower than the deposition rate of the conductive material on the first electrically conductive features 309. In some embodiments, the SAM material includes a head group which contains phosphorus (P), sulfur (S), nitrogen (N), or silicon (Si). In some embodiments, the head group of SAM may include phosphate, sulfate, or silane based materials. In some embodiments, SAM may include benzotriazole (BTA), phosphonic acid, octadecylphosphonic (ODPA), organosulfur compound, thiol (e.g., dodecanethiol, alkanethiol, or the like), or the like. In some embodiments, SAM further includes a tail group which is connected to the head group and which contains an organic chain, such as CHx or the like. Thereafter, the conductive material may be selectively deposited on the first electricallyconductive features 309 by a suitable method as is known to those skilled in the art of semiconductor fabrication, such as ALD, CVD, spin-on deposition, etc., or combinations thereof, to form theconductive capping layer 50. In some embodiments, theconductive capping layer 50 may be selectively deposited on the first electricallyconductive features 309 directly by ALD, CVD, spin-on deposition, etc. using the controlled operation parameters without the selective formation of SAM in advance. In some embodiments, theconductive capping layer 50 may be selectively deposited on the first electricallyconductive features 309 by electroplating. - In some embodiments, after selectively depositing the conductive material on the first electrically
conductive features 309, theconductive capping layer 50 may be thermally annealed at a temperature ranging from 30° C. to 500° C. for a time period ranging from 1 second to 300 minutes. When theconductive capping layer 50 is thermally annealed at a temperature greater than 500° C., the electrically conductive features (for example, metal lines) in thesemiconductor structure 200 may be damaged. The conductive material suitable for forming theconductive capping layer 50 is a thermally or electrically conductive material, examples of which include conductive carbon-based materials (for example, amorphous carbon, graphene, graphite, etc.), conductive polymers (for example, poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT-PSS), polyaniline, etc), conductive organic composites, conductive ceramic composites, conductive metal composites (for example, metals and alloys), and combinations thereof, but are not limited thereto. Theconductive capping layer 50 may have a thickness ranging from 1 {acute over (Å)} to 100 {acute over (Å)}. - The
method 100 then proceeds to block 112 where a plurality of recesses are formed among the first electrically conductive features. Referring to the example illustrated inFIGS. 7 and 8 , the patterneddummy layer 305 is etched away by a suitable etching method as is known to those skilled in the art of semiconductor fabrication, such as dry plasma etching, wet chemical etching, radical etching, gas etching, vapor etching, or combinations thereof, so as to form a plurality ofrecesses 402 among the first electrically conductive features 309. The etching chamber tools suitable for implementing the etching method include a capacitively-coupled plasma (CCP) tool, an inductively-coupled plasma (ICP) tool, etc. The wet chemicals suitable for the wet chemical etching include fluorine-containing chemicals (for example, a hydrogen fluoride (HF) solution), amine-containing chemicals (for example, an amine (NH3) solution), etc., but are not limited thereto. The dry plasma gas and gas phase reactants suitable for the etching method include a fluorine-based gas (for example, HF, CF4, C4F8, etc.), an amine-based gas (for example, NH3), chlorine (Cl2) gas, oxygen (O2) gas, nitrogen (N2) gas, argon (Ar) gas, and combinations thereof, but are not limited thereto. The depths of therecesses 402 can be tuned by, for example, controlling the operation parameters of the etching chamber tools, selecting proper wet chemicals, dry plasma gas, and gas phase reactants, etc. The wet chemicals, the dry plasma gas, and the gas phase reactants for the etching method have an etch selectivity of dielectric to metal ranging from 1 to 600. The depths of therecesses 402 range from 10 {acute over (Å)} to 1000 {acute over (Å)}. The etch landing of therecesses 402 ranges from 10 {acute over (Å)} to 500 {acute over (Å)}. - The
method 100 then proceeds to block 114 where an etch stop layer is formed to cover the spacer layers, the conductive capping layer, and the patterned etch stop layer. Referring to the example illustrated inFIG. 9 , a secondetch stop layer 60 is formed in therecesses 402 and over the first electricallyconductive features 309, and is conformally deposited to cover the spacer layers 401, theconductive capping layer 50, and the patternedetch stop layer 304. Specifically, the secondetch stop layer 60 is conformed in profile to a combined profile of the first electricallyconductive features 309, the spacer layers 401, theconductive capping layer 50, and the patternedetch stop layer 304. - Materials suitable for forming the second
etch stop layer 60 include, for example, silicon, silicon oxide, silicon nitride, silicon carbide, silicon oxycarbide, silicon oxynitride, silicon carbonitride, silicon oxycarbonitride, cobalt, ruthenium, tungsten, titanium nitride, zirconium oxide, aluminum oxide, yttrium oxide, aluminum oxynitride, hafnium oxide, hafnium zirconium oxide, hafnium silicon oxide, hafnium silicon oxynitride, zirconium silicon oxide, hafnium zirconium silicon oxide, hafnium aluminum oxide, hafnium aluminum nitride, zirconium aluminum oxide, ytterbium oxide, tantalum nitride, tantalum silicon nitride, tantalum oxide, tantalum silicon oxide, titanium nitride, titanium silicon nitride, titanium oxide, titanium silicon oxide, and combinations thereof, but are not limited thereto. The conformal deposition of the secondetch stop layer 60 to cover the spacer layers 401, theconductive capping layer 50, and the patternedetch stop layer 304 may be implemented by a suitable deposition process as is known to those skilled in the art of semiconductor fabrication, for example, PVD, CVD, PECVD, ALD, PEALD, etc., or combinations thereof, but not limited thereto. The secondetch stop layer 60 may have a thickness ranging from 1 A to 100 A. The secondetch stop layer 60 includes atop portion 601 and a surroundingportion 602. Thetop portion 601 is disposed over the first electricallyconductive features 309 and covers theconductive capping layer 50. The surroundingportion 602 extends downwardly from thetop portion 601 to cover the spacer layers 401 and the patternedetch stop layer 304. - The
method 100 then proceeds to block 116 where a dielectric layer having air gaps is formed. Referring to the example illustrated inFIGS. 9 and 10 , a dielectric material is deposited in therecesses 402 and over the first electrically conductive features 309 (specifically, on the second etch stop layer 60) to form a second low-k dielectric layer 70 which hasair gaps 701 among the first electrically conductive features 309. - Examples of the dielectric material suitable for forming the second low-
k dielectric layer 70 include silicon oxide, silicon oxycarbide, silicon oxynitride, silicon oxycarbonitride, and combinations thereof, but are not limited thereto, and have a k-value ranging from 1.0 to 3.9, a porosity ranging from 0.1% to 10%, and a hardness ranging from 1 to 10. The deposition of the second low-k dielectric layer 70 on the secondetch stop layer 60 may be implemented by a suitable deposition process as is known to those skilled in the art of semiconductor fabrication, for example, PVD, CVD, PECVD, ALD, PEALD, spin-on deposition, etc., or combinations thereof, but not limited thereto. The second low-k dielectric layer 70 may have a thickness ranging from 100 {acute over (Å)} to 2000 {acute over (Å)}. When the second low-k dielectric layer 70 is made of silicon oxycarbide, an amount of carbon present in silicon oxycarbide is up to 50%. - The
method 100 then proceeds to block 118 where at least one hole is formed in the dielectric layer. Referring to the example illustrated inFIG. 11 , the second low-k dielectric layer 70, the secondetch stop layer 60, and theconductive capping layer 50 are patterned by one or more etching processes (for example, dry etching, wet etching, or a combination thereof) through a pattern opening of a patterned mask layer (not shown) to form at least onehole 702 in the second low-k dielectric layer 70. Specifically, the at least onehole 702 penetrates through the second low-k dielectric layer 70, thetop portion 601 of the secondetch stop layer 60, and theconductive capping layer 50 such that at least one of the first electricallyconductive features 309 is exposed from the at least onehole 702, respectively. Specifically, thehole 702 penetrates through thetop portion 601 of the secondetch stop layer 60 and is positioned within thetop portion 601 of the secondetch stop layer 60. - The
method 100 then proceeds to block 120 where at least one second electrically conductive feature is formed. Referring to the example illustrated inFIGS. 11 and 12 , a second electrically conductive material is filled into the at least onehole 702 to form at least one second electricallyconductive feature 703 electrically connected to the at least one of the first electricallyconductive features 309, respectively. In patterning the second low-k dielectric layer 70, thetop portion 601 of the secondetch stop layer 60, and theconductive capping layer 50, the at least onehole 702 penetrates through thetop portion 601 of the secondetch stop layer 60 and is positioned within thetop portion 601 of the secondetch stop layer 60, such that the second electricallyconductive feature 703 is formed to penetrate through thetop portion 601 of the secondetch stop layer 60 and to be positioned within thetop portion 601 of the secondetch stop layer 60. - The second electrically conductive material may be the same as or different from the first electrically conductive material, and may be, for example, Cu, Al, Au, Ag, W, Co, Ru, Ta, etc., or alloys thereof. The second electrically conductive material may be provided as multiple layers having varying composition, and may be filled into the at least one
hole 702 by a suitable process as is known in the art of semiconductor fabrication, such as electroless plating, electroplating, sputter deposition, or CVD, but not limited thereto. Details regarding the formation of at least one second electricallyconductive feature 703 are the same as or similar to those regarding the formation of the first electricallyconductive features 309 described above with reference toFIGS. 5 and 6 . In addition, similarly to that described above with reference toFIGS. 5 and 6 , before filling copper or the like into the at least onehole 702, the at least onehole 702 may be lined with abarrier layer 704 that prevents electromigration. - The at least one second electrically
conductive feature 703 thus formed penetrates through the second low-k dielectric layer 70, thetop portion 601 of the secondetch stop layer 60, and theconductive capping layer 50, and is electrically connected to the at least one of the first electricallyconductive features 309, respectively. Specifically, the at least one second electricallyconductive feature 703 penetrates through thetop portion 601 of the secondetch stop layer 60 and is positioned within thetop portion 601 of the secondetch stop layer 60. -
FIG. 13 illustrates adual damascene method 500 for manufacturing a semiconductor structure having air gaps in accordance with some embodiments.FIGS. 14 to 25 illustrate schematic views of asemiconductor structure 600 during various stages of thedual damascene method 500 ofFIG. 13 . Thedual damascene method 500 and thesemiconductor structure 600 are collectively described below. However, additional steps can be provided before, after or during thesingle damascene method 500, and some of the steps described herein may be replaced by other steps or be eliminated. Similarly, further additional features may be present in thesemiconductor structure 600, and/or features present may be replaced or eliminated in additional embodiments. - Referring to
FIG. 13 , thedual damascene method 500 begins atblock 502, where a plurality of trenches and at least one via opening are formed in a dielectric structure. Referring to the example illustrated inFIGS. 14 and 15 , adielectric structure 30 formed with a plurality oftrenches 307 and at least one viaopening 307′ is prepared on ametal layer 20′. Themetal layer 20′ is formed on aninterconnect structure 20 disposed over asubstrate 10, and includes adielectric layer 203′ and at least onemetal line 202′ formed in thedielectric layer 203′. Details regarding the formation of the at least onemetal line 202′ are the same as or similar to those regarding the formation of the first electricallyconductive features 309 described above with reference toFIGS. 5 and 6. In addition, similarly to that described above with reference toFIGS. 5 and 6 , abarrier layer 201′ may be formed to prevent electromigration. - The
dielectric structure 30 may be prepared by sequentially depositing a firstetch stop layer 301, adielectric base layer 302′, a first low-k dielectric layer 302, and adielectric capping layer 303 on themetal layer 20′, and patterning thedielectric capping layer 303, the first low-k dielectric layer 302, thedielectric base layer 302′, and the firstetch stop layer 301 by one or more etching processes (for example, dry etching, wet etching, or a combination thereof) through a pattern opening of a patterned mask layer (not shown). In some embodiments, the firstetch stop layer 301 may includes a loweretch stop sub-layer 3011 deposited on themetal layer 20′ and an upperetch stop sub-layer 3012 deposited on the loweretch stop sub-layer 3011. Thedielectric structure 30 thus prepared includes a patternedetch stop layer 304 disposed on themetal layer 20′, a patterneddielectric base layer 305′ disposed on the patternedetch stop layer 304, apatterned dummy layer 305 disposed on the patterneddielectric base layer 305′, and a patterneddielectric capping layer 306 disposed on the patterneddummy layer 305. In some embodiments, the patternedetch stop layer 304 may includes a lower patternedetch stop sub-layer 3041 disposed on themetal layer 20′ and an upper patternedetch stop sub-layer 3042 disposed on the lower patternedetch stop sub-layer 3041. Thedielectric structure 30 is thus formed with the plurality of thetrenches 307 and the at least one viaopening 307′, which are defined bylateral surfaces 308 of thedielectric structure 30. Thetrenches 307 extend through the patterneddielectric capping layer 306 and the patterneddummy layer 305. The at least one viaopening 307′ extends through the patterneddielectric base layer 305′ and the patternedetch stop layer 304, and is disposed below and spatially communicated with at least one of thetrenches 307, respectively. - Materials suitable for forming the lower
etch stop sub-layer 3011 and the upperetch stop sub-layer 3012 independently include, for example, silicon, silicon oxide, silicon nitride, silicon carbide, silicon oxycarbide, silicon oxynitride, silicon carbonitride, silicon oxycarbonitride, cobalt, ruthenium, tungsten, titanium nitride, zirconium oxide, aluminum oxide, yttrium oxide, aluminum oxynitride, hafnium oxide, hafnium zirconium oxide, hafnium silicon oxide, hafnium silicon oxynitride, zirconium silicon oxide, hafnium zirconium silicon oxide, hafnium aluminum oxide, hafnium aluminum nitride, zirconium aluminum oxide, ytterbium oxide, tantalum nitride, tantalum silicon nitride, tantalum oxide, tantalum silicon oxide, titanium nitride, titanium silicon nitride, titanium oxide, titanium silicon oxide, and combinations thereof, but are not limited thereto. The deposition of the loweretch stop sub-layer 3011 and the upperetch stop sub-layer 3012 on themetal layer 20′ may be implemented by a suitable deposition process as is known to those skilled in the art of semiconductor fabrication, for example, PVD, CVD, PECVD, ALD, PEALD, etc., or combinations thereof, but not limited thereto. The first etch stop layer 301 (i.e., a combination of the loweretch stop sub-layer 3011 and the upper etch stop sub-layer 3012) may have a thickness ranging from 1 {acute over (Å)} to 100 {acute over (Å)}. - Materials suitable for forming the
dielectric base layer 302′ include silicon oxide, silicon oxycarbide, silicon oxynitride, silicon oxycarbonitride, and combinations thereof, but are not limited thereto, and have a k-value ranging from 1.0 to 3.9. The deposition of thedielectric base layer 302′ on the firstetch stop layer 301 may be implemented by a suitable deposition process as is known to those skilled in the art of semiconductor fabrication, for example, PVD, CVD, PECVD, ALD, PEALD, etc., or combinations thereof, but not limited thereto. Thedielectric base layer 302′ may have a thickness ranging from 10 {acute over (Å)} to 5000 {acute over (Å)}. - Details regarding the formation of the first low-
k dielectric layer 302 are the same as or similar to those regarding the formation of the first low-k dielectric layer 302 described above with reference toFIG. 2 . - Details regarding the formation of the
dielectric capping layer 303 are the same as or similar to those regarding the formation of thedielectric capping layer 303 described above with reference toFIG. 2 . - The
method 500 then proceeds to block 504 wherein a deposition layer is conformally formed to cover the dielectric structure. Referring to the example illustrated inFIG. 16 , adeposition layer 40 is conformally formed on and covers thedielectric structure 30. Details regarding the formation of thedeposition layer 40 are the same as or similar to those regarding the formation of thedeposition layer 40 described above with reference toFIG. 4 . - The
method 500 then proceeds to block 506 where a plurality of spacer layers are formed. Referring to the example illustrated inFIG. 17 , thedielectric structure 30 formed with thedeposition layer 40 as shown inFIG. 16 is subjected to anisotropic etching to etch away the horizontal portions of thedeposition layer 40 so as to form thedeposition layer 40 into a plurality of spacer layers 401 on the lateral surfaces 308 of thedielectric structure 30. Details regarding the formation of the spacer layers 401 are the same as or similar to those regarding the formation of the spacer layers 401 described above with reference toFIGS. 4 and 5 . - At least one of the spacer layers 401 includes a
lower spacer sub-layer 4011 and anupper spacer sub-layer 4012 separated from thelower spacer sub-layer 4011 by anintermediate surface 3051′ of the patterneddielectric base layer 305′. Thelower spacer sub-layer 4011 is formed on alower portion 3081 of a corresponding one of thelateral surfaces 308 exposed by the at least one viaopening 307′, and theupper spacer sub-layer 4012 is formed on anupper portion 3082 of the corresponding one of thelateral surfaces 308 exposed by a corresponding one of thetrenches 307. - It should be noted that the patterned
dielectric capping layer 306 may be moved away together with the horizontal portions of thedeposition layer 40 by the anisotropic etching. - The
method 500 then proceeds to block 508 where first electrically conductive features are formed. Referring to the example illustrated inFIGS. 17 and 18 , a first electrically conductive material is filled into the plurality of thetrenches 307 and the at least one viaopening 307′ to form a plurality of first electrically conductive features 309. At least one of the first electricallyconductive features 309 includes a lower electrically conductive sub-feature 3091 (i.e., an electrically conductive via) disposed in the dielectric patternedbase layer 305′ and electrically connected to the at least onemetal line 202′ of themetal layer 20′, and an upper electrically conductive sub-feature 3092 (i.e., a metal line) disposed in the patterneddummy layer 305 and connected to the lower electrically conductive sub-feature 3091. - Details regarding the formation of the first electrically
conductive features 309 are the same as or similar to those regarding the formation of the first electricallyconductive features 309 described above with reference toFIGS. 5 and 6 . In addition, similarly to that described above with reference toFIGS. 5 and 6 , before filling copper or the like into the plurality of thetrenches 307 and the at least one viaopening 307′, the plurality of thetrenches 307 and the at least one viaopening 307′ may be lined with abarrier layer 310 that prevents electromigration. Theintermediate surface 3051′ of the patterneddielectric base layer 305′ is in contact with a portion of thebarrier layer 301 below the upper electrically conductive sub-feature 3092. - Referring to the example illustrated in
FIGS. 18 and 19 , a planarization treatment (for example, CMP) is then implemented to remove excess of the first electrically conductive material, portions of the spacer layers 401, and the patterneddielectric capping layer 306 until top surfaces of the first electricallyconductive features 309 and the patterneddummy layer 305 to be horizontally flush with each other. - The
method 500 then proceeds to block 510 where a conductive material is selectively deposited on the first electrically conductive features to form a conductive capping layer. Referring to the example illustrated inFIG. 20 , the first electricallyconductive features 309 are then subjected to selective deposition of a conductive material to form aconductive capping layer 50 such that the first electricallyconductive features 309 are covered by theconductive capping layer 50 and the spacer layers 401. Details regarding the formation of theconductive capping layer 50 are the same as or similar to those regarding the formation of theconductive capping layer 50 described above with reference toFIG. 7 . - The
method 500 then proceeds to block 512 where a plurality of recesses are formed among the first electrically conductive features. Referring to the example illustrated inFIGS. 20 and 21 , the patterneddummy layer 305 is etched away so as to form a plurality ofrecesses 402 among the first electrically conductive features 309. Details regarding the formation of therecesses 402 are the same as or similar to those regarding the formation of therecesses 402 described above with reference toFIGS. 7 and 8 . - The
method 500 then proceeds to block 514 where an etch stop layer is conformally formed to cover the spacer layers and the conductive capping layer. Referring to the example illustrated inFIG. 22 , a secondetch stop layer 60 is formed in therecesses 402 and over the first electricallyconductive features 309, and is conformally deposited to cover the patterneddielectric base layer 305′, the spacer layers 401, and theconductive capping layer 50. Specifically, the secondetch stop layer 60 is conformed in profile to a combined profile of the first electricallyconductive features 309, the spacer layers 401, and theconductive capping layer 50. - Details regarding the conformal deposition of the second
etch stop layer 60 are the same as or similar to those regarding the conformal deposition of the secondetch stop layer 60 described above with reference toFIG. 9 . The secondetch stop layer 60 includes atop portion 601 covering theconductive capping layer 50, and a surroundingportion 602 extending downwardly from thetop portion 601 to cover theupper spacer sub-layer 4012 of the at least one of the spacer layers 401 and remaining ones of the spacer layers 401. - The
method 500 then proceeds to block 516 where a dielectric layer having air gaps is formed. Referring to the example illustrated inFIGS. 22 and 23 , a dielectric material is deposited in therecesses 402 and over the first electrically conductive features 309 (specifically, on the second etch stop layer 60) to form a second low-k dielectric layer 70 which hasair gaps 701 among the first electrically conductive features 309. Details regarding the formation of the second low-k dielectric layer 70 having theair gaps 701 are the same as or similar to those regarding the formation of the second low-k dielectric layer 70 having theair gaps 701 described above with reference toFIG. 10 . - The
method 500 then proceeds to block 518 where at least one hole is formed in the dielectric layer. Referring to the example illustrated inFIG. 24 , the second low-k dielectric layer 70, thetop portion 601 of the secondetch stop layer 60, and theconductive capping layer 50 are patterned by one or more etching processes (for example, dry etching, wet etching, or a combination thereof) through a pattern opening of a patterned mask layer (not shown) to form at least onehole 702 in the second low-k dielectric layer 70. Specifically, the at least onehole 702 penetrates through the second low-k dielectric layer 70, thetop portion 601 of the secondetch stop layer 60, and theconductive capping layer 50, such that at least one of the first electricallyconductive features 309 is exposed from the at least onehole 702, respectively. Specifically, thehole 702 penetrates through thetop portion 601 of the secondetch stop layer 60 and is positioned within thetop portion 601 of the secondetch stop layer 60. - The
method 500 then proceeds to block 520 where at least one second electrically conductive feature is formed. Referring to the example illustrated inFIGS. 24 and 25 , a second electrically conductive material is filled into the at least onehole 702 to form at least one second electricallyconductive feature 703 electrically connected to the at least one of the first electricallyconductive features 309, respectively. In patterning the second low-k dielectric layer 70, thetop portion 601 of the secondetch stop layer 60, and theconductive capping layer 50, the at least onehole 702 penetrates through thetop portion 601 of the secondetch stop layer 60 and is positioned within thetop portion 601 of the secondetch stop layer 60, such that the second electricallyconductive feature 703 is formed to penetrate through thetop portion 601 of the secondetch stop layer 60 and to be positioned within thetop portion 601 of the secondetch stop layer 60. - The second electrically conductive material may be the same as or different from the first electrically conductive material, and may be, for example, Cu, Al, Au, Ag, W, Co, Ru, Ta, etc., or alloys thereof. The second electrically conductive material may be provided as multiple layers having varying composition, and may be filled into the at least one
hole 702 by a suitable process as is known in the art of semiconductor fabrication, such as electroless plating, electroplating, sputter deposition, or CVD, but not limited thereto. Details regarding the formation of at least one second electricallyconductive feature 703 are the same as or similar to those regarding the formation of the first electricallyconductive features 309 described above with reference toFIGS. 5 and 6 . In addition, similarly to that described above with reference toFIGS. 5 and 6 , before filling copper or the like into the at least onehole 702, the at least onehole 702 may be lined with abarrier layer 704 that prevents electromigration. - The at least one second electrically
conductive feature 703 thus formed penetrates through the second low-k dielectric layer 70, the top portion of the secondetch stop layer 60, and theconductive capping layer 50, and is electrically connected to the at least one of the first electricallyconductive features 309, respectively. Specifically, the at least one second electricallyconductive feature 703 penetrates through thetop portion 601 of the secondetch stop layer 60 and is positioned within thetop portion 601 of the secondetch stop layer 60. - Referring to
FIGS. 26 to 36 , a method for manufacturing a semiconductor structure having air gaps includes the steps of: sequentially depositing a first etch stop layer 2, a first low-k dielectric layer 3, and a first dielectric capping layer 4 on an interconnect layer 1, which is disposed over a substrate (not shown) and which is formed with an interconnect 11 (for example, an electrically conductive via); forming a plurality of first openings 31 in the first low-k dielectric layer 3 through one or more etching processes; filling a first electrically conductive material into the first openings 31 to form a plurality of first electrically conductive features 32, one of which is electrically connected to the interconnect 11; implementing a planarization treatment (for example, CMP) to remove excess of the first electrically conductive material and the first dielectric capping layer 4 until the first low-k dielectric layer 3 is exposed; removing the first low-k dielectric layer 3 through an etching process; conformally depositing a second dielectric capping layer 5 to cover the first electrically conductive features 32 and the first etch stop layer 2; depositing a second low-k dielectric layer 6 on the second dielectric capping layer 5 to form air gaps 61 among the first electrically conductive features 32; implementing a planarization treatment (for example, CMP) to remove excess of the second low-k dielectric layer 6 and the top portions of the second dielectric capping layer 5 until the first electrically conductive features 32 are exposed; selectively depositing a metal capping layer 7 on the first electrically conductive features 32; sequentially depositing a second etch stop layer 8 and a third low-k dielectric layer 9 on the metal capping layer 7; forming a second opening 91 through an etching process to permit the one of the first electrically conductive features 32 to be exposed from the second opening 91; and filling a second electrically conductive material into the second opening 91 to form a second electrically conductive feature 92 electrically connected to the one of the first electrically conductive features 32. - In the method for manufacturing the
semiconductor structure air gaps 701 are formed among the first electricallyconductive features 309, and theconductive capping layer 50 is selectively deposited on the first electricallyconductive features 309, so thesemiconductor structure semiconductor structure conductive features 309 are covered by theconductive capping layer 50 and the spacer layers 401 prior to formation of therecesses 402. Therefore, the first electricallyconductive features 309 are not damaged during the etching away of the patterneddummy layer 305 to form therecesses 402. Furthermore, since theconductive capping layer 50 is selectively deposited on the first electricallyconductive features 309 prior to formation of the second low-k dielectric layer 70 and the secondetch stop layer 60, the at least onehole 702 for forming the at least one second electricallyconductive feature 703 can be formed directly in the second low-k dielectric layer 70 by patterning without the planarization treatment such as CPM, and the cost for forming the at least one second electricallyconductive feature 703 can thereby be reduced. Moreover, the secondetch stop layer 60 is conformally deposited to include thetop portion 601 that covers theconductive capping layer 50 and the surroundingportion 602 that extends downwardly from thetop portion 601 to cover the spacer layers 401. The at least onehole 702 can be formed within thetop portion 601 of the secondetch stop layer 60 during patterning for forming the at least onehole 702, such that the at least one second electricallyconductive feature 703 can be formed within thetop portion 601 of the secondetch stop layer 60. Therefore, the metal leakage issue can be prevented. - In accordance with some embodiments of the present disclosure, a method for manufacturing a semiconductor structure includes forming a trench in a dielectric structure; forming a spacer layer on a lateral surface of the dielectric structure exposed by the trench; after forming the spacer layer, forming a first electrically conductive feature in the trench; removing at least portion of the dielectric structure to form a recess; forming an etch stop layer in the recess and over the first electrically conductive feature; and after forming the etch stop layer, depositing a dielectric layer in the recess and over the first electrically conductive feature.
- In accordance with some embodiments of the present disclosure, a semiconductor structure includes a first interconnect structure and a second interconnect structure. The first interconnect structure includes at least one electrically conductive element. The second interconnect structure is disposed on the first interconnect structure, and includes a plurality of first electrically conductive features, a plurality of spacer layers, an etch stop layer, and a dielectric layer. The first electrically conductive features are spaced apart from each other, and at least one of first electrically conductive features is electrically connected to the at least one electrically conductive element, respectively. The spacer layers laterally cover the first electrically conductive features. The etch stop layer conformally covers the spacer layers and is disposed over the first electrically conductive features. The dielectric layer is disposed on the etch stop layer.
- In accordance with some embodiments of the present disclosure, a semiconductor structure includes a first interconnect structure including an electrically conductive element; an electrically conductive feature electrically connected to the electrically conductive element; a spacer layer laterally covering the electrically conductive feature; a conductive capping layer disposed on the electrically conductive feature; an etch stop layer conformally covering the spacer layer and the conductive capping layer; and a dielectric layer surrounding the electrically conductive feature, the spacer layer, and the etch stop layer, and including an air gap adjacent to the electrically conductive feature.
- 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 or 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.
Claims (20)
1. A semiconductor structure, comprising:
a first interconnect structure including at least one conductive element; and
a second interconnect structure disposed on the first interconnect structure, and including
a plurality of first conductive features spaced apart from each other, at least one of the first conductive features being electrically connected to the at least one conductive element, respectively,
a plurality of spacer layers laterally covering the first conductive features;
an etch stop layer conformally covering the spacer layers and disposed over the first conductive features, and
a dielectric layer disposed on the etch stop layer.
2. The semiconductor structure according to claim 1 , further comprising a conductive capping layer disposed on the first conductive features and below the etch stop layer.
3. The semiconductor structure according to claim 1 , wherein the dielectric layer includes air gaps among the first conductive features.
4. The semiconductor structure according to claim 1 , wherein the etch stop layer includes a top portion disposed over the first conductive features, and a surrounding portion extending downwardly from the top portion to cover the spacer layers.
5. The semiconductor structure according to claim 4 , further comprising at least one second conductive feature which penetrates through the dielectric layer and the top portion of the etch stop layer so as to electrically connect to the at least one of the first conductive features, respectively, and which is positioned within the top portion of the etch stop layer.
6. The semiconductor structure according to claim 1 , wherein the spacer layers are separated from the dielectric layer by the etch stop layer.
7. The semiconductor structure according to claim 1 , wherein
the dielectric layer includes a lower dielectric sub-layer disposed on the first interconnect structure, and an upper dielectric sub-layer disposed on the lower dielectric sub-layer; and
the at least one of the first conductive features includes a lower conductive sub-feature disposed in the lower dielectric sub-layer and electrically connected to the at least one conductive element, and an upper conductive sub-feature disposed in the upper dielectric sub-layer and connected to the lower conductive sub-feature.
8. The semiconductor structure according to claim 7 , wherein
at least one of the spacer layers includes a lower spacer sub-layer laterally covering the lower conductive sub-feature, and an upper spacer sub-layer laterally covering the upper conductive sub-feature and separated from the lower spacer sub-layer; and
the etch stop layer covers the upper spacer sub-layer.
9. The semiconductor structure according to claim 2 , wherein the etch stop layer includes a top portion covering the conductive capping layer, and a surrounding portion extending downwardly from the top portion to cover the spacer layers.
10. A semiconductor structure, comprising:
a first interconnect structure including a conductive element;
a first conductive feature electrically connected to the conductive element;
a spacer layer laterally covering the first conductive feature;
a conductive capping layer disposed on the first conductive feature;
an etch stop layer conformally covering the spacer layer and the conductive capping layer; and
a dielectric layer surrounding the first conductive feature, the spacer layer, and the etch stop layer, and including an air gap adjacent to the first conductive feature.
11. The semiconductor structure according to claim 10 , wherein
the dielectric layer includes a lower dielectric sub-layer disposed on the first interconnect structure, and an upper dielectric sub-layer disposed on the lower dielectric sub-layer; and
the first conductive feature includes an lower conductive sub-feature disposed in the lower dielectric sub-layer and electrically connected to the conductive element, and an upper conductive sub-feature disposed in the upper dielectric sub-layer and connected to the lower conductive sub-feature.
12. The semiconductor structure according to claim 11 , wherein
the spacer layer includes a lower spacer sub-layer laterally covering the lower conductive sub-feature, and an upper spacer sub-layer laterally covering the upper conductive sub-feature and separated from the lower spacer sub-layer; and
the etch stop layer covers the upper spacer sub-layer.
13. The semiconductor structure according to claim 10 , wherein the etch stop layer includes a top portion disposed over the first conductive feature, and a surrounding portion extending downwardly from the top portion to cover the spacer layer.
14. The semiconductor structure according to claim 13 , wherein the conductive capping layer is disposed between the top portion of the etch stop layer and the first conductive feature.
15. The semiconductor structure according to claim 14 , further comprising a second conductive feature which penetrates through the dielectric layer, the top portion of the etch stop layer, and the conductive capping layer so as to electrically connect to the first conductive feature, and which is positioned within the top portion of the etch stop layer.
16. The semiconductor structure according to claim 13 , wherein the spacer layer is separated from the dielectric layer by the surrounding portion of the etch stop layer.
17. The semiconductor structure according to claim 10 , wherein the conductive capping layer includes a conductive carbon-based material, a conductive polymer, a conductive organic composite, a conductive ceramic composite, a conductive metal composite, or combinations thereof.
18. A semiconductor structure, comprising:
a semiconductor substrate; and
an interconnect structure disposed on the semiconductor substrate, and including
a plurality of first conductive features spaced apart from each other,
a plurality of spacer layers laterally covering the first conductive features,
a conductive capping layer disposed on the first conductive features,
an etch stop layer conformally covering the spacer layers and the conductive capping layer, and
a dielectric layer disposed on the etch stop layer.
19. The semiconductor structure according to claim 18 , wherein the etch stop layer includes a top portion disposed on the conductive capping layer, and a surrounding portion extending downwardly from the top portion to cover the spacer layers.
20. The semiconductor structure according to claim 19 , further comprising at least one second conductive feature which penetrates through the dielectric layer, the top portion of the etch stop layer, and the conductive capping layer so as to electrically connect to the at least one of the first conductive features, respectively, and which is positioned within the top portion of the etch stop layer.
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